Abstract
Introduction
Hair density (HD) studies of marginal traction alopecia (MTA) are few. We aimed to document the HD/cm2, number of hair shafts (HS) per pilosebaceous unit (PU), and HS diameter of different grades of anterior scalp margin MTA (AMTA).
Methods
A cross-sectional descriptive study of 401 women over a 9-month period in 2023. The severity of AMTA was scored using the marginal traction alopecia severity score. Phototrichoscopic evaluation of HD/cm2, HS diameter, and number of HS per PU was done on the alopecic intertemporal, right and left temporal, and the non-alopecic right temporal and intertemporal scalp sites.
Results
The HD/cm2 of the non-alopecic intertemporal scalp site ranged from 282 to 519 cm2 compared to that of the AMTA which ranged from 14 to 349/cm2, p < 0.001. With increasing severity of AMTA, there was a significant decrease in HD: grade 1 had HD of 227.56/cm2 compared to 131.22/cm2 in grade 4 at the intertemporal area, p < 0.001. HS diameter ranged from 0.0087 to 0.0200 mm in grade 1 and 0.0078–0.0100 in grade 4. Single hair units were present in 100%.
Conclusion
Anterior scalp marginal alopecia results in a significant reduction of HD, hair shaft diameter, and number of hair strands. Preventative education on hair care practices and hair styles is advocated.
Keywords: Marginal traction alopecia, Trichoscopy, Phototrichoscopy, Hair density, Marginal traction alopecia severity score
Introduction
Marginal traction alopecia (MTA), characterized by a gradual loss of hair along the scalp margins and hair line recession, is not an uncommon type of hair loss in skin of color women and the documented prevalence of MTA ranges from 15 to 76% [1–4]. MTA does not have a uniform severity [1, 3, 5]. The severity of MTA is graded using the marginal traction alopecia severity score (M-TAS) instrument into mild, moderate, or severe based on the extent of hairline recession and the degree of marginal hair loss [1, 3–5]. A well-observed phenomenon in MTA is the gradual thinning of hair, a reduction in hair density (HD), and retention of hair along the margins (fringe sign) [4, 6, 7]. A PubMed search reveals several studies of the trichoscopy and histopathological features of MTA and only one case study documenting HD/cm2 [4, 8, 9]. This case study by Ancer-Arellano et al. [9] did not state the HD in the non-alopecic scalp sites. There are no phototrichoscopic studies of the number of hair shafts (HS) per pilosebaceous unit (PU) and HS diameter (mm) in MTA nor comparative studies of these features in different grades of MTA. Phototrichoscopy is the use of photographic images with magnifications of up to ×200 in the identification of HS and the automated calculation of HD within a specified field and this is reported as HD/cm2.
This study aimed to document the HD/cm2, number of HS per PU, and HS diameter (mm) of different grades of anterior MTA (AMTA) and to compare these parameters between the different grades of FMTA. In addition, we sought to compare these parameters between the AMTA sites with normal, non-alopecic intertemporal and temporal scalp sites of the participants. Findings from the study will serve as a basis for AMTA evaluation, monitoring of improvement with treatment, hair restorative treatments, and patient education on safe hair care practices.
Methodology
This was a prospective cross-sectional descriptive study of 401 women who have anterior marginal alopecia (AMTA) over a 9-month period (January to September 2023). The study was conducted at the skin clinics of the Lagos State and the Kaduna State University Teaching Hospitals following ethical approval. Verbal and written consents were obtained from all the participants. Excluded from the study were pregnant women, women who had other forms of hair loss, and women taking systemic medications that could affect HD.
Consecutive adult females who had AMTA were purposively recruited into the study until the required number of 400 participants was achieved. The diagnosis of AMTA was clinical. In this study, any female found to have hair loss uniformly along the anterior scalp margins with no facial papules was deemed to have AMTA [10]. Participants were visually examined for AMTA, fringe sign, tightness of their braids/weaves and for follicular papules or folliculitis. In addition, the severity of AMTA was scored using the M-TAS [5]. The M-TAS typically scores six areas around the margins of the scalp with the mastoid bone, temporal and sternocleidomastoid bones as land marks (online suppl. material; for all online suppl. material, see https://doi.org/10.1159/000543221). Each area is scored 1–4 signifying increasing severity, giving a total maximum grade of 24. Severity of MTA is graded as follows: 1–3 as mild, 4–6 as moderate, and >6 as severe [5]. The maximum score any participant in this study could have was 12 as only the anterior scalp margin was evaluated. For objectivity, photographic examples of grades 1–4 MTA were utilized in the evaluation of participants (Appendix I). One hundred participants were to be recruited into each grade of AMTA, but this was not possible especially with grade 4 due to the low frequency of the grade [1, 3, 11]. Phototrichoscopic evaluation of HD (number of hair shafts per square centimeter), terminal and vellus hair shaft diameter (millimeter), and number of hair shafts per pilosebaceous unit was done using the Catseye phototrichogram system; CASLite Nova (Navi Mumbai, India: Catseye System and Solution). The CASLite system utilizes a magnification of ×70 for HS diameter and a magnification of ×200 for HD [12]. HD was automatically calculated by the software. Phototrichoscopy was done at 3 anterior scalp sites (right and left temporal and intertemporal) (Figures 1a–c and 2a–d). For the comparative arm, phototrichoscopy features were assessed 3 cm away from the alopecic area of the right temporal and intertemporal anterior scalp sites.
Fig. 1.
a Picture of grade 1 anterior scalp marginal traction alopecia (temporal). b Phototrichoscope of HD, grade 1 anterior scalp frontal marginal traction alopecia: non-alopecic right temporal. c Phototrichoscope of HD, grade 1 anterior scalp marginal traction alopecia: alopecic right temporal.
Fig. 2.
a Picture of grade 4 anterior scalp marginal traction alopecia (temporal). b Phototrichoscope of HD, grade 4 anterior scalp marginal traction alopecia: non-alopecic right temporal. c Phototrichoscope of HD, grade 4 anterior scalp marginal traction alopecia: alopecic right temporal. d Phototrichoscope of anterior scalp marginal traction alopecia: flambeau sign and tenting of the skin from severe traction.
Data were analyzed using SPSS version 26. Categorical variables such as age groups, family history of hair loss, and MTA grades are presented as percentages. Numerical variables such as the hair parameters in alopecic and normal non-alopecic scalp areas are presented as means, standard deviation, and range. ANOVA was used to compare the means of hair parameters between MTA grades. Student’s t test was used to compare means of hair parameters between normal areas and alopecia areas. For all statistical test, p < 0.05 was considered significant.
Results
The age range and the mean age (±sd) of the 401 participants were 5–89 years and 44.04 (±15.4) years. The age distribution of the participants is shown in Table 1. The response to a family history of AMTA was yes in 186/401 (46.4%), no in 99/401 (24.7%), and I do not know in 116/401 (28.9%). While 86/401 (21.4%) knew the cause of AMTA, 315/401 (78.4%) did not. Only 81/401 (20.2%) knew that AMTA can be treated. Fringe sign was observed in 58/401 (14.5%), 18/401 (4.5%) had folliculitis, and 180/401 (44.9%) had a tight hair style (Table 1).
Table 1.
Sociodemographic parameters and severity of AMTA
| Variable | n = 401 | % |
|---|---|---|
| Age group, years | ||
| <10 | 1 | 0.2 |
| 10–19 | 19 | 4.7 |
| 20–29 | 56 | 14.0 |
| 30–39 | 86 | 21.4 |
| 40–49 | 99 | 24.7 |
| 50–59 | 74 | 18.5 |
| ≥60 | 66 | 16.5 |
| Duration of hair loss, years | ||
| <1 | 19 | 4.7 |
| 2–5 | 92 | 22.9 |
| 6–10 | 42 | 10.5 |
| >10 | 67 | 16.7 |
| Do not know | 181 | 45.1 |
| Awareness that TA can be treated | ||
| Yes | 81 | 20.2 |
| No | 42 | 10.5 |
| Do not know | 278 | 69.3 |
| Observed FMTA grade | ||
| 1 | 99 | 24.7 |
| 2 | 97 | 24.2 |
| 3 | 115 | 28.7 |
| 4 | 90 | 22.4 |
The sites of AMTA were observed to predominantly have single unit hairs compared to the non-alopecic areas. Also, the number of PU with two HS was greatly reduced, and no PU had three or four HS in the alopecic sites (Table 2).
Table 2.
Comparison of number of hair shafts per follicular unit between alopecic and normal non-alopecic sites
| Alopecic site | Non-alopecic site | |||||
|---|---|---|---|---|---|---|
| single | two | single | two | three | four | |
| Intertemporal region | 401 (100.0%) | 66 (16.5%) | 400 (99.8%) | 399 (99.5%) | 156 (38.9%) | 26 (6.5%) |
| Right temporal region | 401 (100.0%) | 23 (5.7%) | 392 (97.8%) | 399 (99.5%) | 95 (23.7%) | 20 (5.0%) |
| Left temporal region | 401 (100.0) | 32 (8.0%) | ||||
There were significant differences in HD, average HS diameter, and number of HS per PU between the alopecic and the normal, non-alopecic areas. The HD and the number of HS in the normal area were almost twice that in the alopecic area. The HD/cm2 of the non-alopecic intertemporal scalp site ranged from 282 to 519/cm2 compared to that of the AMTA which ranged from 14 to 349/cm2, p < 0.001 (Table 3).
Table 3.
Comparison of hair parameters between alopecic and normal non-alopecic areas
| Variables | Alopecic area | Normal area | t test | p value |
|---|---|---|---|---|
| mean (sd) [range] | mean (sd) [range] | |||
| HD/cm2 | ||||
| Intertemporal | 193.73 (56.82) [14–349] | 378.71 (41.85) [282–519] | 52.491 | <0.001 |
| Right temporal | 158.05 (48.73) [19–302] | 313.64 (26.82) [235–415] | 56.014 | <0.001 |
| Average number of hair shafts/cm2 | ||||
| Intertemporal | 20.59 (5.96) [3–37] | 40.25 (4.44) [30–55] | 52.972 | <0.001 |
| Right temporal | 16.77 (5.20) [2–32] | 33.33 (2.83) [25–44] | 56.014 | <0.001 |
| Inter-follicular distance, mm | ||||
| Intertemporal | 0.240 (0.041) [0.15–0.40] | 0.177 (0.016) [0.14–0.24] | 28.665 | <0.001 |
| Right temporal | 0.255 (0.043) [0.15–0.41] | 0.186 (0.018) [0.15–0.25] | 29.641 | <0.001 |
| Vellus hair ratio | ||||
| Intertemporal | 43.62 (16.56) | 4.85 (3.41) | 45.919 | <0.001 |
| Right temporal | 40.58 (15.53) | 5.42 (4.30) | ||
| Average terminal hair diameter, mm | ||||
| Intertemporal | 0.0099 (0.0006) [0.0078–0.0200] | 0.0110 (0.0029) [0.01–0.02] | 7.438 | <0.001 |
| Right temporal | 0.0099 (0.0004) [0.0078–0.0100] | 0.0110 (0.0030) [0.01–0.02] | 7.278 | <0.001 |
| Average vellus hair thickness, mm | ||||
| Intertemporal | 0.0032 (0.0009) [0.0000–0.0049] | 0.0040 (0.0013) [0.0000–0.0049] | 35.462 | <0.001 |
| Right temporal | 0.0033 (0.0009) [0.0000–0.0049] | 0.0040 (0.0019) [0.0000–0.0031] | 27.622 | <0.001 |
There were significant differences in parameters on comparison of different grades of AMTA. With increasing severity of AMTA, there was a significant decrease in HD, p < 0.001. Hair shaft diameter and number of HS per PU decreased with increasing severity of AMTA irrespective of scalp site, p < 0.001 (Table 4).
Table 4.
Comparison of hair parameters between different grades of frontal marginal alopecia
| Variable | MTA grade | p value | |||
|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | ||
| mean (sd) | mean (sd) | mean (sd) | mean (sd) | ||
| HD/cm2 | |||||
| Intertemporal | 227.56 (45.38) | 219.56 (42.02) | 191.73 (44.73) | 131.22 (42.66) | <0.001 |
| Right temporal | 187.64 (38.13) | 179.86 (37.45) | 153.47 (37.88) | 107.87 (40.70) | <0.001 |
| Left temporal | 193.76 (44.29) | 186.34 (42.29) | 155.69 (38.33) | 113.29 (37.54) | <0.001 |
| Range | 104–339 | 94–349 | 57–320 | 14–264 | |
| Mean (sd) | 202.98 (46.06) | 195.25 (44.09) | 166.96 (43.98) | 117.46 (41.42) | |
| Average number of hair shafts/cm2 | |||||
| Intertemporal | 24.15 (4.81) | 23.31 (4.47) | 20.32 (4.78) | 14.07 (4.28) | <0.001 |
| Right temporal | 19.96 (4.02) | 19.09 (4.02) | 16.28 (4.03) | 11.40 (4.33) | <0.001 |
| Left temporal | 20.53 (4.74) | 19.78 (4.50) | 16.53 (4.09) | 11.98 (3.39) | <0.001 |
| Range | 11–36 | 10–37 | 6–34 | 2–28 | |
| Mean (sd) | 21.5 (4.9) | 20.73 (4.70) | 17.71 (4.69) | 12.48 (4.32) | |
| Average vellus hair ratio | |||||
| Intertemporal | 43.69 (15.36) | 48.25 (15.56) | 44.93 (14.04) | 36.88 (19.68) | <0.001 |
| Right temporal | 41.63 (13.86) | 44.10 (14.86) | 42.92 (13.66) | 32.61 (17.59) | <0.001 |
| Left temporal | 42.12 (14.19) | 48.33 (14.00) | 44.77 (15.17) | 36.28 (20.26) | <0.001 |
| Average terminal hair diameter, mm | |||||
| Intertemporal | 0.010 (0.0010) | 0.0099 (0.0003) | 0.0098 (0.0005) | 0.0098 (0.0005) | 0.005 |
| Right temporal | 0.010 (0.0002) | 0.0099 (0.0003) | 0.0098 (0.0004) | 0.0098 (0.0005) | <0.001 |
| Left temporal | 0.010 (0.0010) | 0.0098 (0.0010) | 0.0098 (0.0005) | 0.0098 (0.0005) | 0.027 |
| Range | 0.0087–0.0200 | 0.0010–0.0100 | 0.0078–0.0100 | 0.0078–0.0100 | |
| Mean (sd) | 0.0100 (0.0008) | 0.0098 (0.0006) | 0.0098 (0.0004) | 0.0098 (0.0005) | |
| Average vellus hair diameter, mm | |||||
| Intertemporal | 0.0034 (0.0009) | 0.0034 (0.0009) | 0.0031 (0.0009) | 0.0029 (0.0009) | <0.001 |
| Right temporal | 0.0033 (0.0008) | 0.0035 (0.0008) | 0.0033 (0.0008) | 0.0030 (0.0011) | <0.001 |
| Left temporal | 0.0035 (0.0009) | 0.0034 (0.0009) | 0.0033 (0.0007) | 0.0028 (0.0009) | <0.001 |
| Range | 0.0022–0.0049 | 0.0021–0.0049 | 0.00–0.0049 | 0.00–0.0049 | |
| Mean | 0.0100 (0.0008) | 0.0099 (0.0006) | 0.0033 (0.0008) | 0.0029 (0.0010) | |
Discussion
AMTA is not an uncommon type of hair loss in women of color, and this is due to their hair care practices and hair styles [1–3, 13]. This study revealed significant differences in HD per square centimeter (HD/cm2), hair shaft (HS) diameter (millimeters), and the number of hair shafts per pilosebaceous unit between different severities of frontal marginal traction alopecia (AMTA). These differences were also observed when the scalp sites affected by AMTA were compared to normal, non-alopecic scalp sites. The study, in addition, revealed the frequency of different severities of MTA.
HD was significantly reduced in the AMTA areas compared to the normal, non-alopecic areas. HD has an inverse relationship with the number of HS to which it is dependent. Thus, a reduction in the number of HS results in a decrease in HD. The HD of the AMTA site ranged from 14 to 349/cm2 compared to 282–519/cm2 of the normal area. This HD is important not only in evaluating and monitoring treatment but also in surgical therapies for hair restoration especially in Africans. Having a knowledge of the normal HD will serve as a guide in restoring the hair to as near normal as possible. The average HD in our study differed from that reported in the case report by Ancer-Arellano et al. [9]. The authors opine that this may be due to the well-known phenomenon of ethnic variation in HD [14–17]. Also, their study was a case study of one person, and the range of HD was not stated making comparison of reports difficult.
The HS diameter significantly differed between the AMTA and the normal scalp site. In addition, the number of vellus hairs was more at the AMTA sites. This was not unexpected as with increasing severity of AMTA, there is increasing miniaturization of the hair and a consequent increase in the number of thin hairs [4, 8].
The sites of AMTA were observed to have predominantly single hair units when compared to the normal scalp areas. Also, the number of PU with two HS was greatly reduced, and no PU had three or four HS in the alopecic sites. These differences in the number of HS per PU can be adduced to the etiology of MTA. TA occurs due to constant pulling of HS from hair styling methods or the weakening of HS by chemical relaxers [3, 7]. The result of this is a gradual reduction of the number of HS per PU with increasing severity of the AMTA. Furthermore, AMTA is a biphasic form of hair loss with scaring occurring with increasing severity [3, 7, 8]. The finding of single hair units MTA in this phototrichoscopic study is similar to that previously reported in trichoscopic and histopathological studies of MTA [4, 7, 8].
On comparison of the HD/cm2 and the number of HS per PU of the different grades of AMTA, there was a significant difference between the grades, and these differences were more obvious when grade 4 was compared to grade 1. The mean HD/cm2 was significantly reduced from 219.56/cm2 in grade 1 to 131.22/cm2 in grade 4 at the intertemporal scalp site. The average number of HS per PU in grade 1 was twice that in grade 4 irrespective of the scalp site. Vellus hairs were infrequent in grade 4. With increasing severity of MTA, there is scarring, a closure of follicular openings, destruction of vellus hairs, and retention of sparse terminal hairs [4].
Terminal hair diameter significantly reduced with increasing AMTA severity. The diameter of grade 1 terminal hairs was 0.01 mm compared to 0.0098 mm in grade 4 terminal hairs. This was not an unexpected finding. Terminally, MTA being a biphasic type of hair loss is associated with miniaturization, hair thinning and scaring with increasing severity. The constant pulling of the hair, the alteration of protein content, and weakening of the hair strand all contribute to the thinning of the hair with increasing severity.
The severe form of AMTA, grade 4 was the least frequent type observed. This finding is similar to that documented in other studies where the M-TAS instrument was utilized [3, 4, 11]. Traction alopecia (TA) is a biphasic form of alopecia which is reversible in its mild and moderate stages. Early identification of the hair loss and stoppage of the inducing hair care practices with reversal of the hair loss is postulated to be the reason for the infrequency of grade 4 MTA [4]. Fringe sign was observed in a few patients. Fringe sign is found with increasing severity of MTA with a frequency of 100% in some studies [1, 6, 7, 18]. Although fringe sign has no prognostic importance for MTA, it is diagnostic when found in the setting of MTA [6]. Our study had a lower frequency of fringe sign than that previously reported. This may be because the study participants mostly had mild and moderate grades of FMTA. Also, the frequency of fringe sign varies between studies [6, 7, 18].
This study was limited by an inherent flaw in the Catseye instrument. The hairs had to be identified by the researchers before the automated calculations. So, if the researcher missed any hair strands, this could lead to errors in the values. Another limitation was the lack of histopathological diagnosis for complete exclusion of androgenetic alopecia and frontal fibrosing alopecia. The strength of the study lies in the proportionate allocation of participants into the different grades of AMTA. In addition, photographic images were utilized in the grading of AMTA, thus eliminating any subjectivity.
In conclusion, frontal marginal alopecia results in a significant reduction of HD in comparison with normal scalp sites. There is significant miniaturization of hair shafts and a predominance of single hair units. These features become worse with increasing AMTA severity. Furthermore, grade 4 TA which is irreversible is infrequent. There is a need for the education of females on hair care practices and hair styles to prevent AMTA or to retard the worsening of AMTA.
Statement of Ethics
This study protocol was reviewed and approved by Lagos State University Teaching Hospital Ethics Review Board (LREC/06/10/1750). Verbal and written consents were obtained from all participants aged 18 years and above. For participants less than 18 years of age, verbal and written consents were obtained from their parents and guardians. In addition, verbal and written assents were obtained from the children.
Conflict of Interest Statement
The authors have no conflicts of interest to declare.
Funding Sources
None of the researchers received funding for this work.
Author Contributions
E.L.A.: conception, design and collection of data, draft of the manuscript, review of the final manuscript, and approval of this version for publishing. H.S.: design and collection of data, draft of the manuscript, review of the final manuscript, and approval of this version for publishing.
Funding Statement
None of the researchers received funding for this work.
Data Availability Statement
The data that support our findings are not publicly available for reasons of the privacy of the study participants. However, the data are available from the corresponding author E.L.A.
Supplementary Material.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
The data that support our findings are not publicly available for reasons of the privacy of the study participants. However, the data are available from the corresponding author E.L.A.