The hair follicle consists of the follicle proper and the hair bulb, which creates the hair, its strain and the sebaceous gland. Any damage to the follicle or bulb can cause alopecia.
The growth cycle of hair consists of the Anagen phase (growth), the Catagen phase (transition) and the Telogen phase (shedding). Disturbance of any of these phases results in alopecia.
Normally 90-95% of the hairs are in the anagen phase and 5-10% in the telogen phase, and a loss of 50 to 100 hairs a day is normal. When the rate of loss increases over 100 hairs a day, alopecia can be observed. This is called telogen effluvium. This form of hair loss is common in iron deficiency anaemia and endocrine and metabolic diseases. Any disturbance of the anagen (growth) phase of the hair causes anagen alopecia. This form is observed during the use of chemotherapeutic substances and radiation for malignant diseases.
Which are the factors that evoke the development of Alopecia?
Surgery and childbirth can cause transient alopecia. Anxiety and stress, constant pulling of hair during brushing, and hair styling techniques can lead to traction alopecia. There are also cases of alopecia that have an autoimmune aetiology, such as pathological cicatricial alopecia in case of lichen planus, systemic lupus erythematosus, scleroderma, etc. Also, chronic use of certain medications, such as antidepressants, cortisone or hormonal preparations, can cause hair thinning, hair loss and eventually alopecia, which in most cases is reversible if the medication is discontinued. Alopecia is also due to:
- Hormonal factors
- Chronic inflammations
- Fungal infections
- Thyroid disease
- Hypervitaminosis A
- Iron deficiency
- Poor diet
Which are the common types of Alopecia?
The most common form in men, in a percentage of more than 90%, is androgenetic alopecia (male pattern hair loss, commonly known as baldness), while in women, androgenetic alopecia is the cause in about 50% of cases. The most common form in children is alopecia areata (spot baldness) and traction alopecia, which is due to pulling the hairs and usually has psychological roots.
Localised traumatic alopecia, resulting from injuries, burns, accidents etc. is a quite frequent form of alopecia. Furthermore, there are frequent cases of traumatic alopecia resulted from a previous hair transplantation performed with the older hair restoration technique named Strip or FUT, as this technique always leaves a postoperative linear scar in the donor site in the occipital region of the head. Traumatic alopecia usually involves the scalp, but can also involve facial hair, especially the eyebrows and beard.
What is the clinical picture of Androgenetic Alopecia in men?
The pattern of androgenetic alopecia in men consists in thinning or complete lack of hair in the frontal, temporal and parietal regions, while the occipital area is spared. At a microscopic level, it has been found that the hair follicles in the constant hair growth zone do not have androgen receptors, making them less susceptible to the action of male hormones and the subsequent hair loss.
What is the clinical picture of Androgenetic Alopecia in women?
In women, the total lack of hair in a particular area is extremely rare compared to men, in whom it is extremely frequent. The continuing growth of hair in the occipital and lateral temporal regions, even in old age, is a feature that is observed worldwide and defines the so-called ‛constant hair growth zone’, which serves as a donor site for hair transplantation.
Androgenic alopecia in women shows a more diffuse form, normally with retention of the front hairline, hair thinning in the frontal and parietal regions, and hair growth that is maintained in the occipital region. It can be circumscribed (patchy), diffuse or total. It is also divided in cicatricial (scarring) and non-cicatricial (non-scarring).
How are the various types of Cicatricial Alopecia being classified?
- Pathological cicatricial alopecia
- Lichen planus
- Systemic lupus erythematosus, scleroderma
Other auto-immune diseases
- Neoplastic aetiology (basal-cell or squamous-cell carcinoma)
- Inflammatory aetiology (bacterial, fungal or viral)
- Congenital aetiology (ichthyosis, congenital absence of skin)
Traumatic cicatricial alopecia
- From injury or burn
- Damages after radiation
- Scars resulted from previous hair transplantation performed with the FUT or Strip method
How are the various types of non-Cicatricial Alopecia being classified?
- Normal alopecia
- Alopecia areata (spot baldness)
- Androgenetic alopecia (male pattern hair loss)
- Alopecia induced by various harmful factors
- Diffuse alopecia, depending on the image of trichogram
- Telogen alopecia or telogen effluvium
- Dystrophic or anagen alopecia
- Mixed alopecia
- Diffuse alopecia, depending on the harmful factor
- Due to endocrinal disorders
- Caused by medicinal and chemical substance
- Caused by nutritional and metabolic disorders
- Chronic diffuse alopecia
- Traumatic alopecia
- Traction alopecia