The Cross-Section Trichometer: A New Device for Measuring Hair Quantity, Hair Loss, and Hair Growth

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1 The Cross-Section Trichometer: A New Device for Measuring Hair Quantity, Hair Loss, and Hair Growth BERNARD COHEN, MD BACKGROUND Office physicians are unable to measure hair quantity, hair loss, and hair growth in a simple and meaningful manner. One solution is to measure the cross-sectional area of a bundle of hair that is growing within a premeasured cross-section of scalp. OBJECTIVE The objective was to design a mechanical device that precisely measures the cross-sectional area of a bundle of hair and design a device that can precisely delineate an area of scalp. It was assumed that density and diameter changes are evidenced by changes in the bundle cross-sectional area and that growth and loss are the result of density and diameter changes. These assumptions were confirmed using various sized bundles of known diameter non-hair filaments. MATERIALS AND METHODS Bundles of hair and surgical silk fibers were tested using a mechanical device that compressed the bundle and measured its cross-sectional area. Balding patients were categorized according to their observed severity of the loss. Bundles of their uncut hair from 4-cm 2 scalp sites were measured and the values were compared to the patient s category of hair loss severity. RESULTS In patients with balding, there was a direct correlation between the bundle s cross-sectional area and the observed severity of the loss. The cross-sectional area was expressed as square millimeters of hair per square centimeter of skin 100 (mm 2 /cm 2 100) and named the trichometric index (TI). Using surgical silk fibers, there was a direct correlation between the bundle s cross-sectional area and the number of filaments, the diameter of the filaments, and the dry weight of the filament bundle. Using aggregates of cut human hair, there was a direct correlation between the cross-sectional area and the dry weight of the bundle. CONCLUSION This prototype device shows promise as a diagnostic instrument for measuring changes in hair quantity (mass), hair diameter, and hair density, as evidenced by preliminary studies using silk sutures, cut human hair, and patients with various degrees of balding. Formal clinical studies are needed. Although the device itself showed a high degree of precision, the accuracy and reproducibility of the measurements can be compromised if the sampling method is not carefully performed using magnification. The device is intended for use on uncut hair that is more than 1 inch in length. Dr. Cohen holds patents on the method and device described in this report and will receive royalties on the sales. Hair loss affects 75% of men and 10% of women, but office physicians are unable to measure its parameters in a simple and meaningful way. Precise instrumentation and methodologies have been limited to research centers and industry laboratories where clinical studies and drug evaluations are performed. The office physician needs a rapid, easy, and precise method for measuring a patient s clinical status. Hair quantity is determined by measuring the hair s density (n/cm 2 ) and diameter (mm). Hair loss and hair growth result when there is a fluctuation in one and/or the other. An ideal hair-measuring technology should reflect the simultaneous influence of both density and diameter. The present devices and methods have advantages and limitations (see Table 1). In discussions of hair density and hair diameter, it is helpful to draw the distinction between the termsf shedding and thinning, since both result in hair loss. In states of shedding, hairs with diameters of normal size fall out. It is normal to shed about 50 to 100 Department of Dermatology and Cutaneous Surgery, University of Miami, Miller School of Medicine, Coral Gables, Florida & 2008 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc. ISSN: Dermatol Surg 2008;34: DOI: /j x 900

2 COHEN TABLE 1 Comparison of Trichometer Device and Method with Existing Hair-Measuring Methods Category Description Advantages Disadvantages Hamilton-Norwood Comparison Scale 1,2 chart Black & white drawings depict 12 stages of balding. Quick, simple and widely accepted. Incomplete hair loss not depicted by shades of gray. Hair Loss Gross visual Severity Scale 3 analysis Observe visual ratio of hair to skin, choose between 6 categories. Quick, no chart required. Imprecise. Has not gained acceptance. Hair count 4,5 Magnified image analysis Hairs 430 microns are counted using scalp images of trimmed hair. Suitable for FDA studies or casual office evaluations. Hair must be cut. Office video cams are not precise. Clinical Photography Gross image analysis Popular, simple, informal. Cameras and light sources vary. Quick, easy, inexpensive. Quality varies with technique and hardware. Global Gross image Photography 4,5 analysis Technically formalized hardware. Photos evaluated by panel. High quality images suitable for FDA studies. Hairstyle control. Compares B&A of same patient only. Dry hair weight 5 Laboratory quantitative analysis Hair is cut and weighed after a fixed period of growth. Industry gold standard. Suitable for FDA studies. Technically difficult. Requires strict humidity control. Trichoscan Digital image software 6,7 analysis Hair is cut & dyed. Computer analyses scalp images of trimmed hair. Most precise and accurate of office methods. Hair must be cut and dyed. Not widely popular. Scalp Biopsy 8 Surgical A 4 mm punch biopsy is sectioned transversely and examined. Identifies vellus intermediate, and terminal hairs Path interpretation is difficult to learn. Post op care. Growth rate 9 Direct measurement of hair length Hair growth in mm is measured over a fixed period of time (30 days). Accurately quantifies anagen activity. Clinical relevance is of questionable value. Trichometer device & method Mechanical measurement of intact hair Measure X-sectional area of hair bundle from delineated area of scalp. No cut hair. Quick and simple. Device is precise. Sampling can be imprecise. Hair must be 1 inch. FDA, Food and Drug Administration. Reflects influence of density and diameter Scale = 0 to 5 Density = 1 Diameter = 0 Density = 3 Diameter = 3 Density = 5 Diameter = 2 to 3 Density = 2 Diameter = 2. Density = 3 to 4 Diameter = 3 to 4 Density = 5 Diameter = 5 Density = 4 to 5 Diameter = 4 to 5 Density = 2 Diameter = 4 to 5 Density = 0 Diameter = 0. Density = 5 Diameter = 5 Measures hair mass within a delineated area Not measured. Accuracy = 2 Precision = 1 Accuracy = 3 Precision = 5 Not measured. Not measured. Accuracy = 5 Precision = 5 Accuracy = 4 Precision = 5 Sample too small for adequate measurement. Not measured. Sampling & Device Accuracy = 4 Precision = 4 34:7:JULY

3 THE CROSS-SECTION TRICHOMETER hairs per day, but in pathologic states of effluvium and alopecia areata, shedding can be quite profound. Underlying skin becomes more and more visible as the shedding progresses. The hair density analysis or hair count will accurately reflect this disorder. Hair thinning is a disorder characterized by the gradual miniaturization in the length and diameter of individual scalp hairs. Underlying skin becomes more and more visible as the hairs become smaller and smaller. Thinning affects an estimated 75% of men, and although it occurs in 10% of healthy women, it might indicate an endocrine abnormality in a small group of those affected. Unlike shedding, thinning is not diffuse in its distribution over the entire scalp, but almost always appears in a pattern that spares the posterior and sides of the lower scalp, creating a familiar horse-shaped fringe that persists in spite of the most advanced cases. Thinning will eventuate in lowered density as the affected hairs vanish. Thinning, in its earliest stages, cannot be visualized and is difficult to diagnose and quantify. Simple density counts comparing the permanent occipital fringe to an area of balding are of limited value because the balding area has a mixed population of normal-sized and miniaturized hairs (see Figure 1). The anatomic fluctuations of density and diameter result in hair loss and growth, but it should be noted that the changes in hair diameter are considerably more influential than changes in hair density. Coarse hair has a diameter of about 80 mm, average hair about 70 mm, and fine hair about 60 mm. Surprisingly, an 80-mm hair has almost twice the mass of a 60-mm hair because it has approximately double the cross-sectional area (3.14 r 2 = cross-sectional area). If two individuals have the same number of hairs, all the same length, the one with coarse hair has almost twice as much hair mass as the one with fine hair. A 10% change in hair density will result in a 10% change in hair quantity. A 10% change in diameter will result in a 20% change in hair quantity. Because Figure 1. In hair loss due to balding or thinning, the hairs have a wide range of diameters. When a hair count is performed, any hair with a diameter larger than 30 mm is counted as one hair. hair length varies with style, it is not considered in the calculation of hair quantity. Objectives The broad objective was to develop a technology for measuring the quantity of hair in a defined area of scalp. If the density and diameter of hair determines its quantity, and the cross-sectional area of an aggregate of hair reflects the range of densities and diameters within that aggregate, then the crosssectional area of the aggregate reflects the quantity of hair within the aggregate. Based on this theory, a technology was designed to measure the crosssectional area of all the hairs in an aggregate of hair from a premeasured area of scalp. This value could be used to quantify the hair that is present and then, by comparison, quantify the amount of hair that has been lost or gained. To measure the collective cross-sections of hair in the premeasured area, the ideal method/device must first capture the hairs and compress the loose aggregate into a rectangular bundle, before the measurement is performed. The device should always compress the bundle with the same exact load, regardless of the 902 DERMATOLOGIC SURGERY

4 COHEN TABLE 2. Correlation between Silk Strand Diameter and the Bundle Cross-section Strands per bundle hair sample size. The compressive force should completely compact the bundle, but not with a force so excessive to damage the captured hair. The load should be incrementally applied with mechanical precision rather than casual hand-applied force. A precise scientific instrument should be included to measure the cross-sectional area of the compressed and fully compacted bundle. It is preferable that no hair is cut and no physician supervision or oversight be required. The device should be of small size, sensibly priced, widely available, easy to use, and capable of generating results in a short period of time. The Resultant Device and the Method for Testing Bundle Crosssection (mm 2 ) Eighty-strand bundles of mixed-size suture material were measured. A device/method that fulfilled the above objectives was created. It was tested using silk filaments and human hair to determine if changes in the crosssectional area were correlated to changes in the hair density (n/cm 2 ) and/or diameter (mm) (see Tables 2 4). The device is a self-contained mechanical unit with a rectangular anodized aluminum body that is held in the right hand like a hypodermic syringe (see Figure 2). Extending from one end of the body is a hookshaped arm, and from the other end of the body, a spring-loaded shaft with a retainer cap. The hook and the cap are at opposite ends of one contiguous shaft. An electronic sensing unit with LED display is externally mounted on the side of the housing and attached internally to the shaft. When the cap at the end of the shaft is pressed with the thumb, the hook arm extends out of the body at the opposite end, and its travel distance is displayed on the LED screen in hundredths of a millimeter. When the thumb is released, the hook retracts back toward the body. To measure the cross-sectional area of a hair sample, the arm is extended and hooked around a bundle of hair that has been gathered from a 2 2-cm area of scalp (see Figures 3 5). When the thumb is lifted, the bundle of hair is captured in a 1 4-mm chamber created on the ledge of the metal housing through which the hook passes. The number and diameter of hairs in the captured bundle determine the height of the hair within the chamber. When initially captured, the bundle is slightly compressed and not yet compacted. The mid portion of the long shaft has a threaded portion that passes through a large threaded knob at the base of the body. When the knob is turned clockwise on the shaft, it compresses a heavy internal spring. As a result, the spring delivers a precise load to the upper and lower surface of the captured rectangular bundle and compacts it. TABLE 3. Correlation between Silk Strand Density and the Bundle Cross-section No. of Strands Cross-Section (mm 2 ) Cross-section divided by No. of strands Twenty-strand bundles of 5-0 suture material were measured. 34:7:JULY

5 THE CROSS-SECTION TRICHOMETER TABLE 4. Correlation between Silk Strand Weight and Bundle Cross-section Number of Strands Grams Crosssection (mm 2 ) Grams Divided by Cross-section The device is engineered to deliver no more or less than the same predetermined load each time it is engaged, regardless of the bundle size. When the internal spring is compressed exactly 1 cm, the height of the compacted bundle in its rectangular capture chamber is displayed as millimeters on the LED screen. For an 800-hair sample (about average for 4 cm 2 of scalp), the normal range of values falls between 3.00 mm (for fine hair about 60 mm) to 4.00 mm (for coarse hair about 80 mm). The value displayed on the screen is expressed as square millimeters of bundle cross-section per 4 cm 2 of scalp surface. When divided by 4 and multiplied by 100, the normal range of values conveniently falls Figure 3. A close-up view of the capture hook at the end of the shaft, in its extended position. between 75 to (fine to coarse hair). This value has been arbitrarily named the trichometric index (TI). It should be noted that extensive testing was performed using various sized chambers, compression loads, and sample sizes before the optimal mechanics of the device were determined. A load was chosen that would compress the loose bundle to a point of complete compactionfthe point beyond which no further compaction would occur. When this load was determined, sample hair bundles were microscopically examined to determine if fracture or visible distortion of the hair had occurred. On the basis of Figure 2. The trichometer device is shown in its neutral position. When the shaft is pressed using the thumb, a J- shaped hook extends from the body. The travel distance of the shaft within the body is displayed as millimeters on the LED screen. Figure 4. The skin is marked with a four- or eight-legged marking template moistened with waterproof ink. 904 DERMATOLOGIC SURGERY

6 COHEN its cross-sectional area. A fourth test sought to establish a correlation between the observed hair loss severity and the TI (mm 2 hair per cm 2 scalp 100). Figure 5. The device shown applied to an isolated bundle of hair from a 2 2-cm area of scalp in the mid frontal area. this, an optimal and safe standard compression load was chosen. A working prototype was then designed to deliver that same optimal load regardless of the height (or the amount) of hair in the chamber. A selfbraking mechanism was added to prevent the operator from overtightening the threaded knob and exceeding the optimal load. The spring material and its design were further refined to insure that the compression spring was in the center of its path from fully opened to fully compressed, i.e., in the mid range of its spring constant curve. This was done to minimize the imprecision that metal springs typically display at both ends of their compression curves. Results of Testing The device was intended to indirectly measure density and diameter by directly measuring the crosssectional area of all the hairs in a premeasured area of scalp skin. Four tests were performed. The first was designed to determine if the device could detect and measure small changes in surgical silk diameter (mm). A second test was designed to determine if the device could detect and measure small changes in the bundle densities of hair and surgical silk (n/cm 2 ). A third test was designed to determine if there was a correlation between the weight of the bundle and Diameter measurements were performed using strands of 3-0, 4-0, 5-0, and 6-0 nonsterile braided surgical silk (Havel s Inc., Cincinnati, OH). Each material was hand-measured using an electronic micrometer (L.S. Starrett Co., Athol, MA), and strand diameters were found to vary within 15 to 20 mm along their length. The average diameters were 3-0 = 150 mm, 4-0 = 100 mm, 5-0 = 75 mm, and 6-0 = 50 mm. Thirteen mixed-size bundles, composed of 80 strands each, were prepared. The bundles were incrementally reduced in size by mixing large caliber strands with smaller caliber strands. Each bundle was then measured using the device. When the results were plotted, the cross-sectional area of each bundle was reduced in a sequence that mirrored the incremental reduction of suture caliber (see Table 2). Density measurements were performed using the same braided silk suture material. Bundles of 5-0 silk, the diameter of which is approximately 75 mm (equivalent to the diameter of average-sized hair), were prepared. Eight bundles, containing 20 filaments each, were prepared. First the device was used to measure the cross-sectional area of one bundle. The device was then opened and a second bundle was added. A second measurement was made, the device was then reopened, and a third bundle was added, etc. Bundles were incrementally placed in the device until they totaled 160 fibers. The results are posted in the chart below (see Table 3). The crosssectional area of the bundle was increased in a sequence that mirrored the incremental increase of filaments added. The ratio of the number of filaments to the cross-sectional diameter remained constant. Weight measurements were performed using a 150-strand bundle of 5-0 surgical filaments to determine if the weight and the cross-sectional area of a bundle were directly correlated. The bundle was weighed on an electronic analytic balance, and its 34:7:JULY

7 THE CROSS-SECTION TRICHOMETER TABLE 5. Correlation between Hair Weight and Bundle Cross-section Number of Hairs Grams Crosssection (mm 2 ) Grams Divided by Cross-section X X minus X minus X minus X minus X minus X minus X minus X minus Hairs were cut from a bundle of approximately 600 hairs; the bundle was reweighed, and its cross-section remeasured cross-sectional area was measured using the new device. The measurements were performed in a laboratory with no humidity control. Then two filaments were cut from the bundle, the bundle was reweighed, and its cross-section was remeasured. This was repeated six times. The cross-sectional area of the bundle was reduced in a sequence that mirrored the incremental reduction of bundle weight. The ratio between the weight and the cross-section remained constant (see Table 4). Weight measurements were then performed using a bundle of cut human hair to determine if the weight and the cross-sectional area of a bundle were directly proportional (see Table 5). The bundle contained an aggregate of hairs (approximately 400) collected from three different women, all of whom had undergone hair coloring or permanents in the previous 3 months. The measurements were performed in a laboratory with no humidity control. Hairs were incrementally cut from the bundle, the bundle was reweighed, and its cross-section was remeasured. This was repeated eight times. The cross-sectional area of the bundle was reduced in a sequence that mirrored the incremental reduction of bundle weight. The ratio between the weight and the crosssection progressively increased over a period of 30 minutes. This was thought to be the result of ambient moisture absorption during the time required to collect the data. With both silk filaments Figure 6. The Hair Loss Severity Scale uses the visible ratio of hair to skin to quantify the hair within a localized area of scalp. 3 (A) minimal, (B) mild, (C) moderate, and (D) severe. and hair, the cross-sectional areas of the bundles were reduced in a sequence that mirrored the incremental reduction of bundle weight. Twelve male patients, age 23 to 67 years with balding, were examined without magnification. The observed ratio of hair to skin in the vertex area of each patient was estimated by an observer familiar with the Hair Loss Severity Scale (HLSS) technique. Each patient was placed into one of four categories: minimal = much more hair than skin, mild = more hair than skin, moderate = more skin than hair, and severe = much more skin than hair (see Figure 6). The hair within the 4 4-cm center of the vertex area was isolated and measured with the device and expressed as TIs (mm 2 hair per cm 2 skin 100). The TI and hair loss severity of each patient were charted to determine if there was a correlation (see Table 6). Collection of the Hair Sample It was clear from the onset that the sampling method would be quite influential in determining the system s total precision. A 2 2-cm square of hair- 906 DERMATOLOGIC SURGERY

8 COHEN TABLE 6. Correlation between Observed Hair Loss Severity and the TI (mm 2 Hair per cm 2 Scalp 100) in 12 Patients with Vertex Balding Patient Severity Score TI 1 Minimal 47 2 Minimal 44 3 Minimal 44 4 Mild 36 5 Mild 33 6 Mild 33 7 Moderate 25 8 Moderate 28 9 Moderate Severe Severe Severe 21 bearing scalp skin was chosen because it could be easily handled without magnification and represented a somewhat generous sample (see Figures 4 and 5). On average, this area contained about 800 hairs in patients with no loss. The sampling precision was important since fewer than 3 hairs would, for example, change the cross-sectional value of the bundle from 3.30 mm 2 to 3.31 mm 2. The collection method was not formally tested for reproducibility because there were simply too many different combs, tapes, clips, magnifying devices, marking pens, templates, stencils, bundling contraptions, etc., to be evaluated. A standardized method for isolating the hair sample from the 4-cm 2 area (and immobilizing the adjacent hair) has not been formalized at the time of this publication. It should be pointed out that the 4 cm 2 site may be the shape of a triangle, rectangle, or hexagon and is not limited to a 2 2-cm square. Several other issues needed to be addressed. Should the hair be wet or dry? It was easier to gather a sample with precise margins on the 2 2-cm square if the hair was wet. Wet hair measurements were performed in a salon setting where each client almost always presented to the operator immediately following a shampoo. Almost all the samples gathered in the physician s office were performed on dry hair. In both situations, a fine-toothed comb, 2.5 magnifying loupes, and a sharp wooden toothpick were used. The easiest method of demarcating the 2 2-cm area was marking dots with a four-legged or eight-legged template moistened on a pad of waterproof ink. Stencils with four and eight holes were also used to place the dots on the scalp skin surface. When wet hair was combed away from the 2 2-cm square of scalp, it remained immobilized and firmly in place. When the sampling was performed on dry hair, the peripheral hair required immobilization with hair clips or gummed tape. Several methods of demarcating the area, without placing any ink marks on the skin, have since been developed and will be the subject of a future report. The second sampling issue to be addressed was returning to precisely the same site for a subsequent measurement. Typically, when industry standard hair counts and hair weight measurements are performed, dots are tattooed on the scalp to identify the previous test site. Tattoos were performed on several patients, although our goal was to design a method that would not require a permanent tattoo. Initially we used a quick and easy method of simply extending a nonstretchable 4-mm tape from the junction of the upper lip and nose columella, on to and over the tip of the nose, then up the forehead and along the midline of the scalp along which the hair was cleanly parted. An ink dot was simultaneously placed on the tape and the scalp. The tape was removed and the distance between the two points on the tape was measured with a ruler attached to a tabletop. However, vertical movement of nose tip caused a 5- to 7- mm variation in the anterior to posterior dot placement. The movement from side to side was considered less critical when returning to the exact same site because the gradation of hair loss in a balding individual is much greater along the sagittal axis than the coronal axis. Several methods and devices that enable a return to precisely the same area, without skin marking, have since been developed and will be the subject of a future report. 34:7:JULY

9 THE CROSS-SECTION TRICHOMETER It is important to note that the sampled hair must be a minimum of 1 inch (2.5 cm) in length at time of testing. If not, the distance between the scalp surface, the hook/anvil will be too small; and the hair might be painfully tugged when the device is fully engaged. Furthermore, if one anticipates newly emerging hairs, be aware that the new hairs might not be of sufficient length for capture. If the hair is too short, the testing should be postponed until it has grown to adequate length. If a clinical trial is being performed, one should consider the time frame for anticipated emergence of new hairs and their rate of growth. Dates for retesting should be appropriately planned. At first we assumed that the quantity of hair in normal individuals was evenly distributed over the entire scalp. We also assumed that in women with telogen effluvium, diffuse hair loss, or sheddingf the loss was evenly distributed over the entire surface of the scalp. During the pilot studies, it was clear that neither of these assumptions were correct. A significant number of patients with no complaints of hair loss had values higher on the top of the head than in the occipital region. The same unexpected distribution pattern was seen in women with complaints of excessive shedding. Further search of the literature revealed that the hair density changes dramatically with age and that density is in fact unequally distributed over the scalp, often highest on the top of the head. 10,11 These observations are significant if one compares the occipital and midscalp values when attempting to distinguish between diffuse and pattern loss in women with complaints of hair loss. Conclusions and Discussion The method/device described in this report is a mechanical refinement of the author s previous published HLSS. 3 When using the HLSS, the observer is asked to determine the ratio of grossly visible hair to grossly visible skin. A series of photographs give examples of the categories to be chosen. The trichometer device/method described in this report likewise compares the ratio of hair to skin, but uses direct mechanical measurement of the hair and skin cross-sections instead of imprecise visual determination. The HLSS method was used to determine the correlation between hair loss severity and bundle cross-sectional area (see Table 6 and Figure 6). The notion of using an instrument to measure the cross-sectional ratio of hair to skin, for the purpose of measuring the quantity of hair, has been previously described. To the best of our knowledge, it was first described in a 1936 patent by Nessler, 12 who designed a rudimentary device with a rectangular slot for capturing hair and then hand-compressed the hair with a blunt, guillotine-like anvil. The height of the hair in the slot was measured using ruler-like markings engraved on the side of the brass hand-held device. The Nessler device appears to have never gained popularity and no references could be found in the medical literature. In 2001, Arnold 13 formally presented a method for measuring the quantity of hair in a premeasured area of scalp. Although the work was not published, Arnold deserves full credit for introducing the concept of measuring hair quantity using hair/skin crosssectional ratio to the hair science community. Arnold s work served as the inspiration for the method/ device described in this report. Arnold isolated the hair from a premeasured area of scalp, but he chose to measure the hair bundle using a thread wrapped snugly around the bundle s periphery. An ink mark was made on the circumferentially applied loop of thread at the point where the strand crossed over itself. The thread was then removed and stretched out, and the distance between the two marks was measured. Arnold had measured the circumference of the bundle and called this value the hair mass index. Neidel and Bretschneider 14 have described and published the details of Arnold s hair mass measurement technique. Nessler and Arnold did not standardize the load applied to the bundle or control its application with a mechanical apparatus. Because the bundle of hair 908 DERMATOLOGIC SURGERY

10 COHEN is soft and quite compressible, the variability of their load and their method of application introduced significant imprecision. Nessler s ruler and Arnold s measuring thread technique were significantly imprecise as well. The methods of Nessler, Arnold, Hamilton-Norwood, Ludwig, and Cohen (HLSS) are all imprecise and not suitable for scientific studies, and although hair weight measurement, global photography, and hair counts are precise, and suitable for scientific studies, they too have the following limitations as mentioned in Table 1. Global photography requires special equipment and hairstyle conformity. It is designed to compare the relative difference between the before and after appearance of a single patient. It does not generate a single quantitative value for a localized area of the scalp. Hair counts on the other hand do generate a single quantitative value but the value does not reflect the wide variation of diameters seen in conditions of thinning, i.e., androgenetic alopecia. Hair weight measurement, the gold standard, is simply too difficult and time-consuming to perform as an office procedure, and hair weight, hair counts, and Trichoscan all require that hair be cut. The trichometer technology overcomes many of these limitations and generates a value that simultaneously reflects the influence of density and diameter alone. Preliminary study results, using both silk fibers and hair, were the same. The incremental changes in the filament number, filament diameter, and bundle weight were reflected as equal and proportionate incremental changes in the bundle cross-sectional area. It was concluded that the device could be used as a reliable substitute for every instrument and method that is presently used to measure the parameters of hair loss and growth, including the dry hair weight measurementfthe industry gold standard. Although the device itself showed a high degree of precision, it should be emphasized that the accuracy and reproducibility of the measurements can be compromised if the sampling method is not carefully performed using magnification. Returning to the TABLE 7. Possible Applications of the Trichometer Technology 1. Quantify hair mass in a localized area of thinning and/or shedding 2. Quantify the efficacy of proven and unproven hair growth products and devices 3. Quantify the medical treatment response in thyroid disease, iron deficiency, etc. 4. Quantify the results of hair transplantation surgery 5. Quantify the donor hair available for hair transplantation surgery Detect the reversal and recovery from post partum effluvium 7. Detect balding before it is visible 8. Determine a new drug s potential for causing hair loss 9. Determine the incidence of hair loss caused by FDA-approved drugs 10. Provide a simple scoring system for hair loss 11. Provide a new measuring modality for hair science research 12. Enable the office physician to track and measure a patient s clinical status 13. Improve and simplify communication between hair professionals FDA, Food and Drug Administration. same area for retesting without using a tattoo compromises the measurements as well. Both of these issues will be the subject of a subsequent report. The general availability of a simple hair-measuring technology introduces a number of possibilities (see Table 7). Any clinical condition characterized by shedding and/or thinning could be informally quantified and tracked. A patient s hair growth response to minoxidil, finasteride, and iron supplement could be easily measured. The efficacy of popular modalities like low-intensity laser, biotin, and saw palmetto could be informally determined by practicing physicians. Unsubstantiated anecdotes could be challenged, and hair growth scams revealed. Hundreds of common drugs, prescription and over the counter, are known to cause hair loss. These include retinoids, anticoagulants, cholesterol-lowering agents, anticonvulsants, antidepressants, gastric 34:7:JULY

11 THE CROSS-SECTION TRICHOMETER acidity suppressants, cardiac arrhythmia and antihypertensive agents, anti-inflammatory agents, hormones, and weight reduction drugs... plus the entire category of antineoplastic agents. Patients taking these drugs could be evaluated to determine the incidence and magnitude of their hair loss. New drugs could be screened, before FDA approval, to determine if they have the potential side effect of causing hair loss. Marritt observed that a man must lose 50% of his hair mass before the loss can be seen with the naked eye. 16 This was confirmed in Table 6. The TI s of men with minimal hair loss were about 50% lower than the TI s of men with no loss at all. (Normal range for TI is 75 to 100 plus.) Logically, the trichometer might be used to identify men in very early stages of balding, when diameter reduction silently precedes visible loss. By measuring and comparing the frontal and occipital regions of men with normal-appearing hair, a loss as small as 5 or 10% could be detected y perhaps 10 or 15 years before balding was actually visible. The speed of progression and response to treatment could be easily monitored. References 1. Hamilton JB. Patterned loss of hair in men; types and incidence. Ann NY Acad Sci 1951;53: Norwood OT. Male pattern baldness: classification and incidence. South Med J 1975;68: Cohen BH. Hair loss profile, index, and severity scale. In: Haber R, Stough D, editors. Hair Transplantation. Philadelphia: Elsevier; p Canfield D. Photographic documentation of hair growth in androgenetic alopecia. Dermatol Clin 1996;14: Price VH, Menefee E, Strauss PC. Changes in hair weight and hair count in men with androgenetic alopecia, after application of 5% and 2% topical minoxidil, placebo, or no treatment. J Am Acad Dermatol 1999;11: Van Neste D, Dumrotier M, De Coster W. Phototrichogram analysis: technical aspects and problems in relation with automated quantitative evaluation of hair growth by computerassisted image analysis. In: Van Neste D, Lachapelle JM, Antoine JL, editors. Trends in human hair growth and alopecia research. Dordrecht: Kluwer (Amsterdam); p Hoffman R. TrichoScan: combining epiluminescence microscopy with digital image analysis for the measurement of hair growth. Eur J Dermatol 2001;11: Headington J. Transverse microscopic anatomy of the human scalp: a basis for a morphometric approach to disorders of the hair follicle. Arch Dermatol 1984;120: Barth JH, Rushton DH. Measurement of hair growth. In: Serud J, Jemec G, editors. Non-invasive methods and the skin. Ann Arbor: CRP Press; p Olsen EA, Canfield D. Age-related changes in scalp hair density. Tokyo: European Hair Research Society; Van Neste D. Female patients complaining about hair loss: documentation of defective scalp hair dynamics with contrastenhanced phototrichogram. Skin Res Technol 2006;5: Nessler C. Means for ascertaining the hair production of a subject. US Patent 1,962,518, United States Patent Office, June 12, Arnold J. Hair mass index, 4th Annual Congress European Society of Hair Restoration Surgery. Barcelona, Neidel FG, Bretschneider P. Measuring hair mass. In: Unger W, Shapiro R, editors. Hair Transplantation. New York: Marcel Dekker; p Parsley W. Donor site measurement. In: Haber R, Stough D, editors. Hair Transplantation. Philadelphia: Elsevier; p Marritt E. The death of the density debate. Dermatol Surg 1999;5: Address correspondence and reprint requests to: Bernard Cohen, MD, 4425 Ponce de Leon Boulevard, Suite 230, Coral Gables, FL 33145, or thehairlosscenter@ mac.com COMMENTARY The current standards for measuring hair loss and hair growth are laden with problems and inefficiencies. The ongoing search for a simple and accurate method of measuring hair quantity has finally found respite in a novel device recently christened the cross-section trichometer. This device, developed by Dr. Bernie Cohen, is featured in this issue of Dermatologic Surgery. As Dr. Cohen has quoted many times, Medicine is a language of numbers. Simple numbers are used to make a diagnosis like hypertension, diabetes, fever, 910 DERMATOLOGIC SURGERY

12 COHEN and obesity. In fact, it s the manipulation of these numbers that determines the manner by which we treat these disorders. In simple terms, if it can t be measured, it can t be managed. The challenge when evaluating all hair growth drugs is obtaining consistent methodology for measurement. In the past, global photography has been utilized to document the overall change in the appearance of hair from a baseline setting. Using serial global photographs, subjects were classified into distinct categories, i.e., (1) greatly decreased in appearance, (2) slight decrease in appearance, (3) no change in appearance, (4) slight increase in appearance, (5) moderate increase in appearance, and (6) great increase in appearance. Unfortunately, the results are influenced by the F-stop settings on the camera. Additionally, the lighting, film quality, grooming practices, and length of hair must be kept identical to the original baseline photography or an erroneous change of appearance results. Keeping all of the above factors constant is daunting and often not feasible. Global photography is a very crude and often inaccurate method of assessing hair quantity in terms of both loss and growth. Global photography cannot properly reflect changes in hair counts. To assess changes in hair counts, microphotographic techniques are utilized. These techniques involve computer overlay in comparison to baseline photographs. The addition of or loss of hairs is determined by a numerical value generated by the computer when comparing photographs. This seems to be a more precise method, but fails to account for the changes in hair shaft diameter, which often show the visible results. Since the positive effect of minoxidil and 5a-reductase inhibitors (finasteride and dutasteride) use is in part due to changes in hair shaft; the hair counts may be minimally affected. In other words, a positive effect may be observed in a study patient by global photography with no change over baseline in actual hair count. It is obvious from the above that our current methods are inadequate in providing a precise change in hair mass. Dr. Cohen s device offers a solution. When it is applied to a bundle of hair, any change in density and diameter will be evident and measured numerically. The article presented herein by Dr. Cohen is well written and deserves the attention of those involved in hair research, clinical evaluations of hair disorders, and practicing hair transplant surgeons. It is not unreasonable to project that at some point in the future residents in dermatology will utilize a device such as the cross-section trichometer to routinely evaluate the success or failure of hair loss treatments in their clinical patients. Practitioners look forward to this device being available to use on their patients. It will be important for clinicians to produce the same, reproducible accurate results as presented in this article. Dr. Cohen is to be applauded for both his success in bringing this to the field and his contributions in advancing hair research. DOW STOUGH, MD Hot Springs, AR 34:7:JULY