Hair Transplant Vocabulary

The medical term for hair loss. There are numerous types of alopecia. Alopecia can be classified as diffused or localized, and by presence or absence of scarring. The most common form of surgically treatable alopecia is androgenic alopecia (AGA).

A common non-scarring alopecia. Although the exact pathophysiology of AA is not clear, it has been determined that it is a T-lymphocyte mediated autoimmune condition that occurs in genetically susceptible individuals. It typically presents itself with sharply demarcated coin-sized patches of alopecia. The scalp is the most commonly affected area, but any hair-bearing area can be involved. Spontaneous remissions and reoccurrences are common. Available treatment options are neither curative nor preventative.

Scalp reduction involves the excision of bald scalp areas, pulling up the surrounding regions of hair growth, and stitching together the wound edges, aiming to gradually cover the whole scalp with hairy parts. It was mostly used to reduce the size of the crown and vertex areas. Scalp reductions were somehow effective but also very destructive for the scalp tissue, had enormous disadvantages, and caused intense pain and frequent postoperative complications. Moreover, due to stretch back, >40% of the removed surface would re-appear bald during the first 12 weeks, the final shape of the remaining bald surface was unnatural, and the unsightly vertical scars of the operations could not be covered by existing hair. The ideal alopecia reduction situation that would fully cover the bald area. In reality, this was never feasible.

A loss of all hair on the scalp.

A loss of all hair on the body.

A vaso-dilatator chemically similar to minoxidil. Studies providing evidence of its efficacy are absent, but it is claimed to be effective in the deduction of telogen hair with anagens inducible activity and prolonged hair follicle age as well.

The anagen stage is the hair follicle’s growth phase, characterized by the intense mitotic activity of the hair follicle, resulting in the formation and development of the hair shaft. Terminal scalp hair grows at a rate of 0.39–0.5 mm/day, and the duration of the anagen in human scalp hair is ≥3 years. Anagen duration in other body areas is significantly smaller, measured in a few weeks. An increase in the duration of anagen does not alter the hair fiber density over the scalp. Instead, it determines to what length the hair can grow. Anagen is shortened in AGA/FPHL.

Defines the multiple structures that firmly attach the lower part of the FU to surrounding tissues which are collectively described as the “anchor system.” It impedes the extraction of the follicular group from the surrounding tissue. The follicular adherence includes the sebaceous gland and the arrector pili muscle, the attachment of the dermis, and the connections between the connective tissue sheath and the surrounding adipose tissue.

Any natural or synthetic compound that stimulates or controls the development and maintenance of male characteristics.

A heritable androgen and age-dependent process resulting in a progressive decline in visible scalp hair density in a sex-dependent defined pattern. AGA classification according to the Norwood-Hamilton scale.

The anterior border of the temporal area of hair that falls inferiorly and vertically from the most posterior limits of the fronto-temporal recessions to a point approximately level with the external auditory meatus.

An agent that blocks the action of androgens.

A tiny smooth muscle that connects the hair follicle with the dermis at the level of the buldge region. It represents the point of maximal Resistance when extraction hair follicles in FUE surgery. They are inserted diagonally to the hair follicle, always on the side that forms an acute angle with the skin. Generally, the APM joins and holds together hair follicles of the same follicular unit at the isthmus level playing a decisive role in follicular integrity. Schematic representation of a 4-hair FU, with a joined arrector pili muscle, surrounded by a collagen capsule that separates the structure from the surrounding dermis and fat.

A piece of tissue surgically removed for microscopic examination.

Body-to-Scalp Hair Transplantation technique or BHT FUE involves the harvesting of Follicular Units (FUs) from areas other than the scalp and their transplantation into the scalp. Body hair includes all hair inferior to and inclusive of the neck and beard. These FUs gradually show an ability to reshape their morphology and iteratively converge to the recipient tissue environment by significantly prolonging anagen duration, eventually growing much longer than earlier. Body hair has an unpredictable and variable yield.

The bulb is the deepest part of the hair follicle, and its principal anatomic component is the dermal papilla. The hair bulb looks like an inverted wine glass, and in horizontal section. It consists of the dermal papilla, rapid proliferating extracellular Matrix and cells, and melanocytes.

The bulge region is the anatomical border of the hair follicle’s permanent portion. It is a convex protrusion of the outer root sheath in the most distal permanent hair follicle stem cells necessary for the development of the hair follicle and the life cycle through their cyclical activation.

It appears to increase the microcirculation in the skin. It was shown to stimulate hair growth in vitro. Studies on the effects of caffeine combined with Minoxidil or in shampoos have shown variable efficacy in AGA. However, all available studies have considerable methodological limitations, and data on the effects of topical caffeine on the hair follicle is insufficient. All these studies on caffeine have significant methodological limitations and are all based on assessments by patients themselves or investigators, which are obviously, of limited value.

The average number of hairs in each follicular unit. Because this is a calculated figure, it is called Calculated Density (CD). It is determined by dividing the number of hairs present in 1cm2 by the number of follicular units observed in the area. Therefore, a CD of 2.1 means that each FU contains an average of 2.1 hairs. CD can be quite variable and range between 1.0 and ≥3.0.

Camouflaging agents reduce the color contrast between the hair color and the color of the scalp. They produce an overall perception of increased hair density. Hair fibers, powder cakes, scalp lotions, scalp sprays and hair crayons are scalp-camouflaging agents.

Catagen is a highly controlled, brief transitional stage between anagen and telogen, during which the hair follicle prepares for its final regression that will take place during telogen. Catagen, which is an ideally regulated process of rapid cellular degeneration and apoptosis In healthy scalp hair follicles,  lasts 2–3 weeks.

A form of scarring alopecia. It mostly affects African-American females. Hair loss usually begins at the vertex and expands outward symmetrically, eventually affecting the entire scalp. The cause of CCCA remains unclear.

It is a pathognomic pattern of FPHL (female Pattern hair Loss) as proposed by Olsen, described as a frontal accentuation with the thinning and widening of the central part of the scalp with hairline preservation. It provides a useful, additional physical feature clue on the differential diagnosis of telogen effluvium from FPHL since it seems to be unique in FPHL.

Uncommon and clinically diverse disorders that result in permanent and irreversible loss of scalp hair. These disorders may be primary, with the follicle itself being the target of the disease process, or secondary, where hair follicles are destroyed as part of a more generalized tissue-damaging event (e.g. deep skin infection, thermal burn, trauma, or ionizing radiation).

It is textural change on the surface of the scalp that occurs due to the placement of the graft in too high a position relative to the recipient scalp. The healing scalp will “rise” to connect with the highly placed graft and will create this uneven and unnatural appearance.

The outermost layer of the hair shaft. The outermost layer of the hair shaft is the cuticle and consists of 6–10 overlapping layers of flat cells (scales). This characteristic flattening of cortical cells occurs during the passage of the hair shaft inside the hair duct. All hair care products target the cuticle, since it is the hair’s shield against all harmful stimuli, and therefore tends to wither. Since hair cannot repair itself, hair care products physically repair the hair by covering the cuticle.  

Cyproterone Acetate is a powerful antiandrogen with potent progestogen and antigonadotrophic properties that directly competes with testosterone and DHT for the occupation of the androgen receptor in target tissues. CPA is one of the most frequently used antiandrogens, in Europe but is not available in the USA. CPA has been used in FPHL, even though its efficacy is considerably limited compared to other compounds, and is probably more helpful in women with hyperandrogenism. All forms of administration of CPA to men are strictly forbidden for the treatment of AGA because of the potent anti-androgenic, castrating-like effects.

High-density follicular unit transplants have been defined as the implantation of >30 FUs/cm2, and the term “dense packing” is used. However, there is no established definition of dense packing. Dense packing aims to produce more even, consistent and natural looking hair. however, it carries the risk of equally excessive vascular damage. This may lead to reduced graft survival and a thinner final appearance compared to transplanting at lower densities. Overall, when the dense-packing technique is performed correctly, it can yield exceptional density and excellent growth rates. However, it is more important to aim for the “adequate” coverage and not the maximum graft density through dense packing.

Analyzes the scalp under high-power magnification to give information on hair density, follicular unit composition and degree of miniaturization.

The number of hairs in a specific area. It can be measured either as Follicular Density (refers to the number of FUs per cm² and is expressed as an average objective value) or Hair Density (the total number of hairs emerging from the scalp per cm²).

Refers to the utilization of different accessories on or around the punch to precisely control the depth to which the punch can enter the skin to avoid unnecessary trauma. When using a microblade to create incisions, it is placed in a handle with a “depth control,” and it is matched to the graft’s length to avoid unnecessary vascular trauma.

A condensate of specialized mesenchymal cells with important inductive properties that is situated at the base of the hair follicle. The dermal papilla contains nerves and blood vessels that supply glucose for energy and amino acids to make keratin. The dermal papilla is "the hair shaft factory" and the command center, dictating shaft size, length, and even cycling of the whole hair follicle. It is likely the target of androgen-mediated events leading to miniaturizations and hair-cycle changes in AGA/FPHL.

DPA in men is manifested as diffuse follicular miniaturization in the frontal, midscalp, and vertex areas but with preservation of a thin -and usually straight- hairline and a healthy, permanent safe donor zone. This pattern of hair loss looks similar to a Ludwig Scale stages I–II on a male scalp. Especially in early DPA stages, hair thinning is prominent without a significant follicular loss (minimal hair shedding), which follows only as the condition progresses.

DUPA differs from DPA in that it lacks a stable, permanent donor zone. In general, DUPA tends to advance quicker than DPA and will usually end up in a horseshoe pattern resembling Norwood stage VII. The critical difference is that the remaining hair looks almost transparent due to the low density. DUPA is 10 times more common in women, and it is probably the most important reason why most women are considered unsuitable candidates for hair restoration surgery.

The most potent natural androgen in humans. Testosterone is converted to DHT by the enzyme 5-alpha reductase. DHT is the implicated androgen in AGA. DHT binds to the Androgen Receptor (AR) with a five-fold affinity compared to Testosterone It is believed that DHT is the key androgen required for the induction of AGA.

The Safe Donor Area (SDA) is defined as the anatomical area that is expected to be permanently covered with hair for a lifetime and will provide permanent coverage when this hair is transplanted to the recipient area. The hair follicles in this area are androgen-independent or androgen-resistant.  

The number of hairs in the donor area measured per square centimeter. In general, patients require a donor density of at least 60 FU/cm2 to be considered for hair restoration surgery.  

The surgical success (different from the cosmetic success) of HRS is based on the “donor dominance theory.” The hair follicles extracted from the occipital safe donor area (SDA), regardless of the area they are transplanted to (scalp or other body areas), will retain their original properties; they will continue o grow, they will not miniaturize or shed due to the biochemical effects occurring locally or systemically in AGA/FPHL.

A form of alopecia usually presented as a diffused, non-scarring variety most commonly involving the scalp. In almost all cases, there is recovery of hair loss after the discontinuation of the medication.

The use of an unsharpened (blunt or hybrid) punch along the course of the follicle to facilitate its extraction.

Dutasteride is a second generation, competitive, irreversible, and potent inhibitor of all isotypes of 5α-R. It is twice as effective as Finasteride and has been approved by the FDA for the treatment of benign prostatic hyperplasia. Dutasteride has been shown to significantly increase hair counts and hair weight, improve the ratio of anagen and telogen hairs and improve scalp coverage. Dutasteride is now becoming a popular “off-label” treatment option in AGA due to its tolerability and good response shown by various randomized control studies and meta-analyses. In most studies, Dutasteride scored better than Finasteride with comparable adverse effects and could become a treatment of choice for AGA in the near future.

Edema is a natural response to surgical injury and is not considered an actual complication; it is more of a surgical side-effect, and the recipient area is the most affected area [11]. In the modern era of “dense-packing” and mega- or giga- sessions, this unwanted “effect” seems to occur more frequently and to a larger extent. It happens more often to women than men and in first-time surgeries of the frontal area and hairline. The tissue fluid retention, both from exudative fluid and fluids introduced under the skin during the procedure, cause forehead edema during and after hair transplant. Swelling results from the cumulative anesthetic fluid loads injected into the recipient site and the venous and lymphatic congestion accompanying incising the recipient site.

Some hair loss conditions go by the name "effluvium," which means an outflow.  Active hair loss denoted by the hair loss of > 100 hairs daily over a longer time period of 2/4 weeks. There are mainly 2 types of effluvium:

-Telogen Effluvium

Telogen effluvium (TE) is probably the second most common form of hair loss dermatologists see. It is a poorly defined condition and happens when there is a change in the number of hair follicles growing hair. If the number of hair follicles producing hair drops significantly for any reason during the resting, or telogen phase, there will be a significant increase in dormant, telogen stage hair follicles. The result is shedding, or TE hair loss.

-Anagen Effluvium

Anagen effluvium is a diffuse hair loss like telogen effluvium, but it develops much more quickly and can cause individuals to lose all their hair. Anagen effluvium is most frequently seen in people taking cytostatic drugs for cancer.

The outer protective, nonvascular layer of the skin.

Exogen phase of the hair cycle is when the club hair is actively released. Although shedding is, without doubt, the most meaningful aspect of hair growth from a patient’s perspective little attention has been given to the actual mechanism of hair shedding. Notably, even though exogen is considered an integral part of the hair growth cycle, it describes what the shaft base is doing and not what the follicle is doing.

An action that details how a graft is divided under the microscope into singles or groups that contain fewer follicles than the original intact group, for example, those to be used in or near the front hairline.

Female Pattern Hair Loss (FPHL) is by far the most common cause of hair loss affecting otherwise healthy women. FPHL is a non-scarring, patterned hair loss, characterized by progressive shortening of the duration of anagen during successive hair cycles and progressive follicular miniaturization with the conversion of terminal to pseudo-vellus hair follicles. Clinically there is a reduction in hair density on the crown and midscalp areas, with typical frontal hairline sparing. For decades it has been considered the female “counterpart” of male AGA despite weaker androgenic parameters than AGA since most women with FPHL do not have an underlying hormonal abnormality; recent research shows that AGA and FPHL are entirely separate entities.    

A term that refers to the number of follicular units per square centimeter. As a metric, it can be applied to both donor or recipient area.

Defined as clusters of hair in the scalp that exit the skin in close proximity to one other and that is separated by a gap from other clusters of hair. The follicular group may consist of more than one follicular unit in a tightly packed distribution on the surface of the skin.

The placing of two follicular unit grafts into one recipient site.

The FU is the natural anatomical and physiological unit of hair follicles in the human skin and scalp and is comprised of the following components:

• One to four (rarely more) terminal hair follicles
• One (rarely more) vellus hair follicles
• Associated sebaceous gland, muscle, vessels, nerves
• A collagen “capsule” surrounding the whole structure and defining the unit

The axiom of modern hair restoration surgery is the preservation of the intact, naturally occurring FU during all steps of the procedure. The FU is the natural physiologic unit and, therefore, should not be divided into smaller parts. During preparation, the grafts should be dissected along their natural cleavage planes. More than one FUs should not be grouped into larger grafts, neither during dissection nor placed together into the same site. Maintaining FUs intact will increase the survival and ultimate hair growth of the grafts and optimize the naturalness of the cosmetic result.

A method of graft harvest whereby punches of various types are used to remove follicular units from the donor region one at a time.

A graft consisting of a single follicular unit.

The term FUT describes the preparation and implantation details of intact FU grafts harvested from the donor area. The donor area per se is managed either according to the principles of the strip excision technique as modern Follicular Unit Strip Surgery (FUSS).    

(a–f) “Lege artis” removal of a strip graft and suturing of the wound. The technique remains practically the same in the modern FUT technique.  

The scalp area that lies between the anterior hairline and a line initially drawn vertically from the left and right tragus and that then gently curve anteriorly.

A condition accepted as a variant of lichen planopilaris. It presents itself with a recession of the hairline along the sideburns and central scalp. It also affects the eyebrows and is more common in postmenopausal women. The treatment involves the use of topical, intralesional and systemic anti-inflammatory treatments.

A natural (or transplanted) zone of hair in the anterior aspect of the scalp, which is separated from the adjacent fringe of hair by an “alley” of alopecia or thinning hair.

The relatively narrow zone of hair that juts out from the posterior aspect of the frontal area or a mid-parietal bridge and that has on each side, a wide and deep fronto-temporal recession.

The non-hair-bearing skin that lies between the superior antero-temporal hairline and the lateral border of the frontal hairline.

A method of hair restoration surgery whereby parallel incisions are made in the donor scalp area to remove a strip. The length and width of the excision depend on the amount of grafts that are required. From this strip, individual follicular units are then dissected under a stereo microscope.

It is a tough layer of dense fibrous tissue that covers the upper part of the skull and lies in between the subcutaneous tissue and the loose connective tissue of the scalp.

1. Epicranial aponeurosis 2. Occipitofrontalis muscle (frontal belly) 3. Corrugator supercilii muscle 4. Orbicularis oculi muscle 5. Occipitofrontalis muscle (occipital belly) 6. Orbicularis oris muscle 7. Buccinator muscle. Latin from top: 1. Galea aponeurotica 2. m. occipitofrontalis venter frontalis 3. m. corrugator supercilii 4. m. orbicularis oculi 5. m. occipitofrontalis venter occipitalis 6. m. orbicularis oris 7. m. buccinator

The numerous techniques and instruments that are available for graft placement. For the placement of grafts in the recipient sites, fine-tipped jeweler’s forceps, straight or angled, and implanter pens of various calibers can be used. There are several techniques for graft insertion, and although their theoretical background is similar, there are important details and discrepancies in the mechanics between them. Atraumatic graft insertion is a critical step during the HRS procedure in order to ensure optimum survival and a natural result. The “art of gentle insertion” requires the highest level of manual dexterity. It is a complex skill to acquire, has a long learning curve, and besides gentle grasping of the grafts, it included maintenance of graft hydration, placement of grafts in the identical angle of site creation and also maintaining appropriate rotation of the natural curvature of the hair graft.

Any external hair-bearing device that is added to existing hair or scalp to give the appearance of a fuller head of hair, i.e.: hair weaves, hair extensions, hair pieces, toupees, non-surgical hair replacements, partial hair prostheses, hair wefts, etc. Devices may consist of human hair, synthetic fiber or a combination of both.

The tubular connection between the epidermal surface and the most distal part of the inner root sheath containing the hair shaft. The hair shafts glides inside the canal as cells are add in the shaft through the dermal papilla, and also the sebaceous gland secretes sebum into the hair canal. The hair canal is the major route of absorption of the scalp.

Hair coverage is the key descriptive term in hair transplant. It is the combination of hair density per unit area of skin with average hair fiber caliber. Improvements in both terminal hair density and average hair diameter work synergistically.

Throughout its life, every single hair follicle cyclically renews itself, sequentially and repeatedly transiting from a phase of active fiber production (anagen) to a resting phase (telogen) through rapid phases of tissue regression (catagen) and regeneration (new anagen). The cyclic activity of the hair follicle requires the regeneration and new assembly of its non-permanent portion during each new hair cycle. On average, the amount of new scalp hair formation matches the amount that is shed, thereby maintaining a consistent covering. There are 5 phases of the hair follicle cycle: an active growth phase called anagen; catagen when the hair follicle regresses; and telogen, when the hair follicle is largely quiescent. Two additional stages of the hair cycle have been described as; exogen (the release of telogen fibers from the hair follicles) and kenogen (the lag in time between the exogen and new anagen fiber development). The length of time each phase takes partly depends on the type of hair follicle involved and its geographic location on the body.

It is the combination of hair follicle density per unit area of skin multiplied by the average number of hairs per hair follicle unit, or simply the number of hairs per unit area of skin.

The most visible product of the hair follicle. The hair’s outer surface, the cuticle, consists of flattened, overlapping cells that form a protective layer over the elongated spindle-shaped cortical cells. The cortex constitutes the middle bulk of the hair fiber, and it surrounds the central medulla, which, when present, is the most central structure. Human hair is a very complex fiber made up of various heterogeneous, morphological components and several different chemical species that manage to interact harmoniously as an integrated system. The main components of hair are of protein origin and constitute 65–95% of its weight. This wide range is explained the differences in water content.

Techniques used to rotate large portions of hair from the sides and back of the scalp to the front and central areas of the head. These technically challenging procedures provided immediate and “impressive” results but did so, at the expense of naturalness and long-term goals. They fully depleted the donor area and only allowed the creation of an unnaturally thick, abrupt hairline.

Hair Grafts

Hair follicles in the form of intact FUs only that have been harvested from the donor area and are ready for transplantation into the recipient area of the scalp.

Hair Mass

Hair mass is the total cross-sectional area of all hairs that emerge from 1 cm² of the scalp surface (range 0.18 mm2 for thin hair to 0.72 mm2 for thick hair).

Hair Plugs or Standard Grafts

A term typically used to describe the technique of harvesting of cylindrical grafts containing 20–30 hair follicles (often called “standard grafts“ ) by 4 mm punches. The donor area wounds were left to heal by secondary intention, and the grafts were inserted in recipient holes created by slightly smaller punches. Results on the recipient area were typically unnatural, hair grew in clumps (doll’s hair, cornrow appearance), in unnatural angles and directions, the scalp skin was uneven (cobblestoning), the loss of hair follicles due to transection was over 50%, while the donor and recipient areas were both severely damaged and permanently scarred.

Recipient area after the creation of recipient sites by removing plugs of the alopecic scalp

Recipient area with noticeable “doll’s hair,” “cornrow growth,” pluggy appearance, and see-through look

Hair follicles are intricate, minuscule, dynamic organs found only in mammals and are the only organs in the human body with the ability to fully undergo a perpetual cyclic process of degradation and renewal throughout their lifetime. The main functions of human hair are protection and communication; it has virtually lost insulation and camouflage roles, although seasonal variation and hair erection when cold indicate the evolutionary history. Human scalp hair has enormous psychological and social meanings and is considered a “Great Communicator”, contributing immensely to non-verbal signaling, social communication, and probably as a powerful fitness indicator in humans.

Hair or cranial prosthesis is a more specific term to describe a device worn to conceal full or partial alopecia secondary to hair disorders, such as AGA/FPHL, medical conditions (scarring alopecias), trauma (wounds, burns, etc.), or iatrogenic alopecias (e.g., chemotherapy). The term wig will be used herein to refer to all scalp prosthesis used for medical purposes. These products address the needs and requirements of patients with various types and degrees of alopecias who desire more natural-looking, virtually undetectable wigs.

HRS is basically a procedure of autologous transplantation/transfer of hair follicles from the androgen-insensitive occipital areas to androgen-sensitive areas, frontal or other. The goal of HRS seems simple enough; however, any experienced HR surgeon will clarify how complex this seemingly simple task is.

The part of the hair follicle that exits the epidermis. It consists of three layers: the medulla, the cortex, and the cuticle.

Schematic of terminal hair fiber structure

The hairline is the most prominent surgical zone in Hair Restoration Surgery because it frames the face and highlights its characteristics. Restoring the hairline is the Hair Restoration Surgeon’s highest cosmetic priority. The goal is to achieve the age-appropriate look that will sustain a natural appearance with the future progression of hair loss.

Major landmarks, borders, and zones of the reconstructed hairline. The hairline consists of many components that “blend” together to obtain the final cosmetic result. (a) Top view, (b) Side view.MPL mid-pupillary line, MFP mid frontal point, LEL lateral epicanthal line, FTA frontotemporal angle, FT frontal tuft.

Refers to the use of a variety of newer, more delicate grafting techniques to alter, camouflage or soften the results of older hair transplant techniques.

The term used to describe removing hair follicles from the donor area. Modern HRS is restricted to FUSS scalp and body-FUE techniques.

That which occurs in a living organism.

Inflammation is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants and is a protective response involving immune cells, blood vessels, and molecular mediators.

The infundibulum is the uppermost segment of the hair follicle, extending from the level of the sebaceous gland duct to the skin surface.

A multi-layered, rigid tube composed of terminally differentiated hair follicle keratinocytes surrounded by the outer root sheath. The inner root sheath (IRS) provides the developing hair with necessary initial support and encloses the primary hair shaft like a scaffold.

Isthmus is the part between the insertion of the muscle and the sebaceous gland duct opening.

The Juri Flap was the most popular flap, a pedicled temporo-parieto- occipital flap that was 20–25 cm long and 4 cm wide that was mobilized, rotated, and sutured in the hairline area to create an entire frontal hairline. These technically challenging procedures provided immediate and “impressive” results but did so at the expense of naturalness and long-term goals. They fully depleted the donor area and only allowed the creation of an unnaturally thick, abrupt hairline.

An overgrowth of scar tissue at the site of a wound in the skin.

An anti-fungal agent. Ketoconazole in high oral doses has antiandrogenic and anti-glucocorticoid properties, inhibits the production of Testosterone and other androgens in both gonads and adrenals. It is used topically for the treatment of seborrheic dermatitis and dandruff and is believed to stimulate hair growth. Ketoconazole shampoo acts synergistically with Finasteride and Minoxidil, it is considered very safe, tolerable, and valuable addition to every AGA/FPHL patient even though the quality of evidence of its efficacy is still poor.

Lanugo hair is the first hair growth produced by the developing hair follicles during intrauterine life, it is fine, soft, poorly pigmented, or colorless and has no central medulla. Lanugo hair growth is usually shed between the 32nd and 36th weeks of gestation. However, in 30% of fetuses, it is retained until birth, to some extent.

The coronal incision is produced at a right angle to the direction of the hair. Coronal grafting causes less vascular trauma, less scarring, and less elevation of the skin. Additionally, there is less popping of grafts due to reduced displacement forces, faster healing because of smaller incisions, and maximum coverage since grafts are placed closer together in an interlocking fashion. The lateral slit technique gives the hair restoration surgeon the ability to control the angle, direction and orientation of the transplanted hair. Schematic of sagittal vs. coronal incisions. Hair direction is also represented with blue arrows. The right side shows coronal incisions made at right angles to the direction of hair growth. The left side demonstrates that sagittal incisions made parallel to the direction of growth.

An autoimmune disorder that causes a permanent scarring alopecia. Adult women make up the majority of the LPP patient population. It is the most common primary cicatricial alopecia and results in a shiny alopecia of the mid-scalp, vertex, or parietal areas. According to the severity of disease, treatment options include corticosteroids, hydroxychloroquine and immunomodulating agents.

Liposomal-encased ATP (Energy Delivery Solutions LLC, Jeffersonville, IN)  is claimed to compensate for the first 4-5 days after HRS during which here is a lack of oxygenation by providing energy to the cells. The liposomal ATP is also supposed to act as a vasodilator, bringing in additional nutrients and decreasing reperfusion injury. Studies on the use of Liposomal ATP are limited, but they suggest an increase in graft survival, and there are anecdotal reports of better graft growth and earlier growth. Liposomal ATP is used as an additive to the holding solution and as a post-operative spray.

A disorder predominantly diagnosed in children, often receding with age.

Low-level laser therapy (LLLT) comprises of low-energy laser treatment—in the range of a few mW—which results in photo-biomodulation effects through the absorption of light photons by tissue photoacceptors to stimulate a biologic response. There are various hypotheses about the mechanism of LLLT in promoting hair growth and the exact mechanism of action is still controversial. Several clinical studies and meta-analyses have been published since 2007, all reporting positive results, some comparable to established FDA-approved hair growth treatments. LLLT devices are easy to apply, have high patient compliance, are safe and effective in patients with AGA/FPHL as both an individual therapy, an adjuvant to standard FDA-approved treatments, even useful in hair transplant surgery for its ability to promote graft survival.

As far as Female Pattern Hair Loss (FPHL) is concerned, Ludwig established in 1977 the three main stages of the FPHL phenotype in women, which are divided into three categories of severity each. According to the classic publication by Erick Ludwig, hair loss in women begins with uniform thinning (coined “rarefaction” by the author) of the crown. According to Ludwig, FPHL progresses with uniform miniaturization of hair follicles in the central-temporal areas and ends up as an oval-shaped area of thin hair, surrounded by a circular band of hair with a variable breadth and normal density. Graphic presentation of Ludwig pattern of FPHL, with a typical example for each grade (a) Grade I. Perceptible thinning of the hair on the crown, limited in the front by a line situated 1–3 cm behind the frontal hair line. (b) Grade II. Pronounced rarefaction of the hair on the crown within the area seen in Grade I (c) Grade III. Full baldness (total denudation) within the area seen in Grades I and II. (Adapted with permission from Ludwig).

Refers to transplanting a large number of follicular unit grafts in a single session. Even though there is no established, official definition of a megasession, most surgeons would agree that the term describes transplanting a vast number of grafts, usually >3000 FUs, in one session. During modern megasessions, 3000–5000 FUs can be transplanted in one sitting, and the goal is to cover all recipient areas densely in “one-pass.” There are strong arguments favoring megasessions: more dramatic results, fewer sessions required, fewer donor area incisions, better graft yield, less overall patient discomfort and downtime, no “plugginess” or “see-through” between surgeries, higher patient convenience and satisfaction, lower cost/ graft, and higher overall value.

Melatonin is a neurohormone released by the pineal gland regulating seasonal biorhythms, daily sleep cycles, and the aging process. Along with circadian rhythm function, melatonin is a potent radical scavenger maintaining the functional integrity of cells with its antioxidant properties. Regarding the in vivo action of melatonin on human hair follicles, data are limited, and trials on topical effects of melatonin in AGA/FPHL and diffuse alopecia are small, poorly designed, biased, suffering from conflicts of interest and the reported results are suspiciously “impressive”.

Mesotherapy consists of superficial scalp injections of pharmaceuticals and vitamin compounds that have been previously been used to treat hair loss via the topical or systemic routes of administration.

The scalp area that lies immediately posterior to the front and extends to the vertex (crown). It is bound laterally by the temporal/parietal fringes. Schematic drawings illustrating the three major anatomically defined recipient zones of the balding scalp.

Miniaturization is the progressive transformation of terminal hair follicles into intermediate and then to vellus hair follicles, which are actually pseudo-vellus, due to the effects of androgens on genetically predisposed individuals. Paradoxical action of androgens in different body areas. After puberty, androgens will stimulate the gradual transformation of vellus hair follicles, producing tiny, colorless hairs into terminal, thick, long, and heavily pigmented hairs (upper row). In complete contrast, androgens may cause miniaturization of hair follicles on specific areas of the scalp in genetically susceptible individuals causing the reverse transformation of terminal follicles to pseudo-vellus ones and AGA (lower row).

A graft containing three or four hairs (small mini-graft) or five or six hairs (large mini-graft). There are many variations of mini-grafts derived from round grafts. These grafts contained parts of adjacent follicular units and unnecessary tissue which made the grafts larger and more pluggy. Micrografts were mostly partial FUs, and minigrafts contained multiple FUs or multiple partial FUs.

Minoxidil was initially developed as a potent antihypertensive, but due to the adverse hypertrichotic effect it had on most patients, it soon became the first compound prescribed to grow hair, used as Minoxidil Topical Solution, MTS. Minoxidil is a KATP channel-opener, however, the exact hair growth stimulating mechanisms remain not fully clarified, yet, it is not related to local vasodilation and is more likely associated with the increase in prostaglandin PGE-2 production in the dermal papilla. Minoxidil increases the size and diameter of AGA-miniaturized hair follicles, gradually converts them into terminal ones, stimulates telogen follicles to enter into anagen, increases the duration of anagen, and decreases the duration of kenogen but does not shorten telogen. The efficacy of 5% MTS is concentration-dependent and consistently superior to 2% MTS. It stabilizes hair loss in 85% of patients, 65% of which report new hair growth, and 30% experience significant hair growth, starting at 8 weeks and reaching a plateau at approximately 12 months.

Hair transplantation using multi-unit grafts. In practice, these grafts may be placed into small round holes, slots, or slits.

Grafts that contain two or more follicular units in a single graft. This term replaces the older mini-graft. In practice today, MUGs contain 2-6 follicular units per graft.

The superior border of the occipital area of permanent hair that surrounds the alopecic or thinning vertex.  

The rotation of the punch back and forth through different arcs and repetitions per minute (RPMs) during penetration. This may be done by hand or automatically.

The outermost layer of the hair follicle. It merges proximally with the inter-follicular epidermis and distally with the hair bulb.  

The superior border of the permanent parietal area of hair that extends posteriorly from a line drawn vertically between the tragus and the beginning of the occipital fringe.  

The entire process of harvesting a fraction of a follicular unit so that one portion of the follicular unit is harvested from the donor area while the other portion of the follicular unit remains in the donor area.

The pilosebaceous unit is a complex mini-organ consisting of three anatomic components: hair follicle, sebaceous gland, and arrector pili muscle. The proportions of these components vary among the different types of hair follicles.

An inactive substance prescribed as if it were an effective dose of a needed medication.

A physical or emotional change occurring after a substance is taken or administered that is not the result of any special property of the substance.

Platelet-rich plasma (PRP) is defined as an autologous supraphysiological concentration of human platelets in a small volume of plasma. It has five- to sevenfold times the platelet concentration of normal blood so that platelets can release growth factors (GFs) in large amounts from dense and alpha granules. PRP actions are based on the infusion of elevated concentrations of these GFs, thereby—theoretically— enhancing the healing capacity and tissue generation in the wound bed. Some hair transplant surgeons have used PRP in hair transplantation procedures either by storing the grafts in PRP until they are placed on the scalp or by injecting PRP into the scalp prior to placement of grafts. The level of evidence of various studies of PRP in AGA is low to medium, and even though most studies report positive results in both mild to moderate AGA/FPHL, a large number of questions remain unanswered, such as candidacy, standardization, preparation and delivery of PRP, dosing parameters, frequency, long-term results and synergy with other treatments.

The removal of one or more terminal hairs by pulling out a follicular group with forceps and intending to remove viable follicles from the donor area that can be ed in the recipient area.

Refers to a group of rare, idiopathic, inflammatory scalp disorders that result in permanent hair loss. Cicatricial alopecias are traditionally classified by their inflammatory infiltrate (lymphocytic, neutrophilic, mixed). The inflammatory process affects mainly the upper portion of the follicle and is followed by a permanent destruction of the hair follicle. Primary cicatricial alopecia frequently starts on the central and parietal scalp before progressing to other sites of the scalp. A lack of follicular ostia is the hallmark of scaring alopecia. Crucial to the diagnosis if cicatricial alopecia is a detailed clinical history and one or two biopsy samples of an active lesion. The goal of any scalp reduction surgery are possible once the lesions are burnt out and stable. Graft survival may not be as good as in androgenetic alopecia and disease reactivation is possible at any time after surgery.

Potent bioactive lipid messengers. They cause many physiological responses.

A chronic asymptomatic primary cicatricial alopecia most often involving the vertex. It is non-inflammatory. The classic appearance of pseudopelade is the so-called footprints in the snow. Potent corticosteroids, hydroxy-chloroquine, and thalidomide have all been used.

The “Hair Pull Test“(HPT) is based on the concept of “gentle” pulling of the hair to investigate the shedding of telogen or pathological anagen hairs. The HPT is an easy and straightforward method used to roughly estimate the ongoing severity and activity of any kind of hair loss, regardless of etiology. Mostly it allows determining whether a patient is experiencing an active stage of hair loss. However, it has low sensitivity and null specificity. The HPT is positive in almost every type of hair loss: anagen effluvium, telogen effluvium, loose anagen syndrome, early cases of AGA/FPHL, even in alopecia areata. However, a negative HPT does not necessarily exclude any diagnosis, not even the diagnosis of hair loss itself. Results can vary depending upon when the hair was last shampooed and combed.

The anterior traction used for the removal of the graft after it has been punched. Grafts may be pulled by a one-hand pull with single forceps, a two-hand pull with two forceps or with suction.

A surgical instrument used to obtain small samples of tissue.

An area where hair loss has occurred and hair follicles will be implanted during a hair transplant procedure. Site creation instruments are either standard disposable hypodermic needles (18G–21G) or custom-cut disposable microblades—0.6–1.2 mm wide and 0.23 mm thick—with a chisel or tipped cutting edge and adjustable length to match the different sizes of grafts. Micropunches are not popular.

Refers to the influence of the recipient site scalp on the growth of transplanted hairs. The recipient area will affect certain hair features, such as growth rate, anagen duration, pigmentation, and survival rate, while it did not affect hair caliber.

The enzyme that converts testosterone to the potent androgen dihydrotestosterone (DHT). The 5α-R enzyme reduces the unsaturated bond in the 4 to 5 position of the testosterone molecule to form DHT. It exists as three isozymes whose tissue distribution varies.

A term that refers to rotation followed by oscillation employed during the penetration of the punch. Rotational speed, arc of rotation, ramp (amplitude from starting position to ending position) of rotation, ramp of arc, and duration of each individual cycle may be controlled.

A procedure whereby the punch is rotated a full repetitive 360-degree cycle during the penetration of the skin. This is usually done by automatically.

Incisions made parallel to the direction of hair growth Schematic of sagittal vs. coronal incisions. Hair direction is also represented with blue arrows. The right side shows coronal incisions made at right angles to the direction of hair growth. The left side demonstrates that sagittal incisions made parallel to the direction of growth.

The over-the-counter Saw Palmetto liposterolic extract contains high amounts of free fatty acids with in-vitro anti-androgenic and 5α-Reductase inhibitory properties. The mild anti-androgenic actions of Saw Palmetto have been documented only in vitro, and there is no convincing evidence that any of these mechanisms are relevant in vivo.

A procedure that is implemented when there is diagnostic uncertainty and when therapeutic options will be altered by an accurate diagnosis. Scalp conditions that usually require biopsy include all forms of scarring alopecia.

Scalp micropigmentation (SMP) is a novel modality of placing a stippled pattern of tattoo dots on the scalp, imitating stubbles of a shaved scalp and giving the illusion of a permanent shading/coverage. These stubbles can also reduce the contrast between scalp skin and hair in areas with thinning or complete baldness, thus efficiently camouflaging lost hair and concealing scalp scars from previous HRS or other etiology.

Scalp reduction involves the excision of bald scalp areas, pulling up the surrounding regions of hair growth, and stitching together the wound edges, aiming to gradually cover the whole scalp with hairy parts. Scalp reductions were very destructive for the scalp tissue, had enormous disadvantages, and caused intense pain and frequent postoperative complications. Moreover, due to stretch back, >40% of the removed surface would re-appear bald during the first 12 weeks, the final shape of the remaining bald surface was unnatural, and the unsightly vertical scars of the operations could not be covered by existing hair. Scalp reduction should not be performed in any case of AGA, but only in cases of repair HRS (to remove wide donor scars) or in cases of scalp reconstructive surgery due to burns, injuries, and tumor removal.

Various alopecia reduction incisions and designs

A superficial cutting of the epidermis and dermis with a punch to produce a superficial circumferential or semicircle incision around a follicular grouping.

The sebaceous gland is a holocrine gland of the skin and almost always accompanies a hair follicle, vellus, or terminal, and the resulting complex is called pilosebaceous unit.  

An inflammatory condition of the skin that most commonly occurs on the scalp, face, and chest. The term dandruff or pityriasis capitis corresponds to a milder form of seborrheic dermatitis that is thought to result from a combination of factors. Clinical features can range from fine scaling of the scalp to erythematous patches. It is a relapsing condition that may require maintenance treatment. Anti-dandruff shampoos are readily available and effective in most cases. Common active ingredients include selenium sulfide, zinc pyrithione, ketoconazole, miconazole, and ciclopirox. Tar-based shampoos are also effective.

Senescent alopecia (SA) or senile alopecia, evolved as a concept from clinical observations that diffuse hair thinning involving the entire scalp may develop after the age of 50 in individuals with no family history of AGA. SA is defined as the non-androgen-dependent hair loss or thinning found in individuals >60 years old involving the entire scalp.

Sentinel hairs refer to the very fine single hairs that scattered in front of the hairline to soften the appearance of the hairline.

This is when a sharp punch is ed along the course of the follicle to facilitate its extraction.

The creation of slits over the recipient area. Every recipient site is a three-dimensional puncture and can vary in volume, size, shape, width, depth, angulation, direction, and orientation. The lower the total volume of each site, the lesser the injury and the resulting microscar that will develop, and the more favorable the conditions will be for grafts to grow. Mixing sagittal and coronal incisions is a common practice. Sagittal incisions are preferred on the hairline’s transition zone and in areas with pre-existing hair (red rectangle), since coronal incisions can cause follicular transection. In all other regions, coronal incisions are preferred (blue circle).

Hair obtained from a donor site directly or sectioned from a larger round graft is ed into a slit made in the scalp by the tip of a scalpel blade.

Dividing the donor strip into sections of variable widths according to the desired graft size called as slivering. The slivering technique has been compared to slicing a loaf of bread, an analogy in which the loaf is the strip and the emerging slices are the slivers. Creating the ideal sliver without transection is the most difficult step in graft preparation. The use of magnification equipment is essential for the creation of slivers.

Spironolactone is a potassium-sparing diuretic with antiandrogenic effects since it decreases Testosterone levels, competitively blocks the androgen receptor, and reduces DHT effects in target tissues. Spironolactone is the most widely used antiandrogen in Dermatology in the USA, primarily used in female acne and as a first-line antiandrogen in hirsutism. It is more rarely used in FPHL, though it does not have any indication in men with AGA due to the potential for feminization. The moderate hair growth potential of Spironolactone is apparent only in high doses, and even though it is generally tolerable, it is not favored by patients since adverse effects are common.

The divergence of follicles from one another that typically occurs at the lower one-third of the follicular unit.

The action of separating a portion of the follicles from a group (follicular family or follicular unit) with the punch in vivo (or in situ).

Cells that reside in rather undifferentiated, quiescent states and form precursors, transient amplifying cells, that provide further proliferation and differentiation into the different cell types. Hair follicle stem cells are multi-potent, capable of proliferation and able to give rise to all cell types of the hair, the epidermis and the sebaceous gland.

A technique for harvesting donor hair that involves the excising of a ellipsoid horizontal section of safe donor hair from the occipital, parietal and occasionally temporal regions. The resulting wound is sutured or stapled and leaves a linear scar. Further splitting of the strip graft into smaller grafts, namely minigrafts and micrografts was initially done and later, intact, naturally-occurring FUs were and still are, isolated.

The border of hair that extends from the fronto-temporal point to a point that lies straight up from the external ear meatus.

Telogen is the phase during which the hair follicle “rests”, since the proliferation and growth of hair cells ceases. In Telogen, the hair follicle remains mostly inactive, hair growth is suspended, and nuclear activity discontinues. The hair follicle continues to be metabolically active, and some early signs of the new hair follicle emerging from its base can be seen.

Refers to the excessive loss of telogen hairs due to an abnormality in hair cycling. It may occur in response to a number of triggers including fever, hemorrhage, severe illness, stress, childbirth, crash dieting and iron deficiency. It typically occurs approximately 3 months from the time of the precipitating event.

Refers to the two upper outer corners where the forehead meets the hairline. This is usually the first area where male pattern baldness is observed, causing the hairline to recede.

Terminal hair follicles (>60 μm diameter; >2 mm length) appear mostly on the scalp and face. Terminal hairs usually have a medulla and are heavily pigmented. Terminal hair follicles anchor deep into the skin (2.558–3.865 mm) and have a bell-shaped, highly distinctive bulb.

A term used to describe the attachment of the connective tissue sheath and outer root sheath to the surrounding adipose of a follicle.

A condition caused by a dermatophyte infection of the hair follicle. It can be inflammatory or non-inflammatory.

A reconstructive balloon-like device that can be used to enlarge the hair-bearing scalp on the sides of the head, providing a larger supply of hair with which to replace the bald areas.  Expertise in the surgical anatomy of the scalp, correct expander choice and placement, meticulous subgaleal undermining, proper galeotomies, and long-term care of patients were all equally necessary. Older techniques of scalp reduction and tissue expansion, excision of many large scarring defects can be accomplished, such as correction of burns, injuries, removal of scalp tumors, and management of scarring alopecias.

An internal device used to stretch the scalp attached with hooks under the galea of the hair-bearing area. Internal dilators, such as the Frechet extender and Silastic suture or custom-made extenders require two procedures. After conventional Alopecia reduction is performed, the extender is attached with hooks under the galea of the hair-bearing area. Then, it is stretched to 100% of its size and hooked to the galea’s undersurface on the contralateral side. The wound is then closed, and the extender is left in place for 30–40 days. The second surgery involves the removal of the extender and undermining, just as during standard AR. The bald area is excised, and the wound is closed.

Keratin-based fibers that adhere to the scalp and existing hair. They help thicken the appearance of existing hair and camouflage the balding areas on the scalp. Toppik Hair Building Fiber magnetizes the hair with static electricity and will stay in place until the following shampoo.

A condition that is caused by excessive stretching of the hair shafts through hair-styling practices. Thinning and recession involve the frontal area but may extend into the temporal regions. Prolonged traction alopecia can scar the new hair follicle and cause permanent hair loss. Hair transplantation is successful in lowering the receded frontal hairline and re-establishing the appropriate density.

A relatively uncommon condition usually detected in early childhood. Hair loss presents itself near the frontotemporal point, in a triangular pattern, with the base of the triangle directed anteriorly. The area may be entirely hairless or have small vellus hairs scattered throughout. Triangular alopecia is amenable to hair transplantation and excellent cosmetic results can be achieved.

The trichophytic closure is a sophisticated closure technique employed to decrease the “show-through” of the donor scar between the hair of the SDA; it allows hair to grow through the scar while the wound heals adding to the camouflage, thus rendering the scar almost inconspicuous.

A dermatoscopy of the hair and scalp. It can be performed with a handheld dermatoscope or a digital videodermatoscopy system. It may be applied in the differential diagnosis of multiple hair and scalp diseases.

This refers to the removal of the dermis and other undesired perifollicular tissues of a graft under the microscope with the aim of slimming the graft.

A simple clinical test that is used to show hair fiber fragility. With one hand, a group of hairs is held while the other hand pulls away the distal ends. Any hair breakage is considered abnormal and is a sign of hair fragility.

An ancillary technique used to minimize follicular transection during strip harvesting by infiltrating the skin subcutaneously with large amounts of normal saline, often containing diluted lidocaine and epinephrine. The injection of this solution causes an artificial swelling of the area, temporarily increasing the distance between FUs and increasing their exit angle, making hair more vertical, thus allowing less transection. Furthermore, the nerves and blood vessels are cushioned from the surgical incision, and the induced swelling caused vasoconstriction through increased hydrostatic pressure, which enhanced hemostasis.

Vellus hairs (<30 μm diameter; <2 mm length) constitute the second type of hair produced by the hair follicle and continue to grow throughout life. They are silky, unmedullated, mostly unpigmented. Vellus hair follicles are the most prominent hair follicle type in the postnatal period, actually representing the miniaturized remnants of terminal hair follicles that comprised the actual coat of hair that our primate ancestors used to have.

The vertex and crown are the most posterior area of the Norwood stage III vertex or greater stages. Although the terms “vertex” and “crown” are very often used interchangeably, they are different regions of the scalp, defined as follows: Vertex is the caudal part of the top of the scalp, anterior to the crown, where the hair still points in a forward direction. Crown is the convex area where the occipital and parietal areas join, and the hair takes a swirling pattern. The natural crown can be conceptually divided into four parts: the center of the whorl, the upper arc, the lower arch, and the vertex transition point.

The VTP corresponds to the midline point where the midscalp horizontal plane gradually shifts to the vertex's vertical plane. The VTP lies immediately posterior to the skull's highest point and approximately where the hair changes from an anterior direction to a whorl arrangement. The VTP is a reference point of high cosmetic significance in HRS. Transplanting as far posteriorly as the VTP is adequate to give the appearance of a full head of hair to individuals classified as stage VI–VII when viewed frontally or frontolaterally. However, one should consider that the location of VTP is inherently subjective since there are several varieties of head shapes and contours.

The circular spiral pattern that exists in the vertex. A whorl pattern of hair direction characterizes the normal crown area. The crown whorl has been considered as an inherited feature. The clockwise whorl pattern (S pattern) corresponds to 75% of patients, while the counter-clockwise whorl pattern (Ζ pattern) corresponds to 11%. Double whorls are very rare (SZ pattern, 3.2%, and SS pattern, 0.6%), while a “diffusion pattern” occurred in 9.8% of the individuals, mainly African-Americans and females.

Crucial to enzyme functioning. Zinc deficiency is also associated with alopecia.