bubble_chart Overview

Alopecia areata is a sudden-onset localized patchy hair loss condition. The affected scalp appears normal, with no inflammation or subjective symptoms. The disease progresses slowly and may resolve and recur on its own. If all the hair on the scalp falls out, it is called alopecia totalis; if all body hair is lost, it is referred to as alopecia universalis.

bubble_chart Etiology

The cause of the disease is currently unclear. Neuropsychiatric factors are considered to be an important factor. Many cases have a history of neuropsychiatric trauma such as prolonged anxiety, worry, sadness, mental tension, and emotional instability before the onset of the disease. In people with seasonal disease, these psychological factors can rapidly worsen the condition during the course of the disease.

Recent studies have shown that the pathogenesis of alopecia areata is related to the following factors:

1. Genetic allergy: About 10-20% of cases have a family history. There are reports of monozygotic twins developing alopecia areata at the same site, and reports of four generations in a family having alopecia areata, suggesting it is a genetic defect disease. From the clinical accumulation of cases, it is observed that people with a genetic allergic constitution are prone to alopecia areata. In the United States, 18% of children with alopecia areata have eczema or asthma, or both; about 9% of adult alopecia areata patients; the proportion of children with total alopecia is even higher, at 23%. In Japan, 10% of alopecia areata patients have a genetic allergic constitution, while in the Netherlands, it is as high as 52.4%. However, the Netherlands includes positive skin tests and a family history of genetic allergy in the criteria for establishing a genetic allergic constitution. Therefore, the diagnostic criteria for genetic allergic constitution vary among countries and regions, and the data cannot be compared. A domestic study by Chen Shengqiang on the correlation between alopecia areata and human leukocyte antigens showed that the frequency of HLA-A₉

antigen in alopecia areata patients (16.67%) was significantly lower than in normal people (32.65%), supporting the genetic allergic factor of alopecia areata from an experimental perspective.

2. Autoimmunity: The rate of alopecia areata patients with some autoimmune diseases is higher than in the normal population. For example, 0-8% have thyroid disease; 4% have vitiligo (only 1% in normal people). Reports on the presence of autoantibodies in alopecia areata patients vary, with some saying they exist and others saying they have not been found. A domestic study by Zhang Xinjiang on T cell subsets and β₂ microglobulin suggested that alopecia areata patients have T cell network disorder and humoral immune dysfunction.

3. Down syndrome: The incidence of alopecia areata is increased in Down syndrome, often presenting as total or universal alopecia. The presence of autoantibodies in these patients is significantly increased.

It is currently not certain that alopecia areata is an autoimmune disease, but it can be accompanied by autoimmune diseases, and temporary effectiveness of corticosteroids suggests a tendency towards the autoimmune theory.

Japanese researcher Ikeda, after long-term investigation, believes that alopecia areata can be divided into four types, each with different onset ages, clinical manifestations, and prevention.

Type I, genetic allergic (10%): early onset, long course, 75% develop total alopecia.

Type II, autoimmune (5%): usually occurs after the age of 40.

Type III, pre-hypertensive (4%): onset in young adults, with one or both parents being hypertensive patients. The condition progresses rapidly, with a 39% incidence of total alopecia.

Type IV, common type (83%): not belonging to types I-III. Onset in late childhood [third stage] or young adults, total course usually within 3 years, single alopecia areata can regrow hair within 6 months. 6% develop total alopecia.

bubble_chart Pathological Changes

Lymphocyte infiltration is observed around and beneath the hair follicles, with some cells invading the follicular wall and causing degeneration of the hair matrix cells. In the follicles of shed hairs, new vellus hairs may form. The newly grown hairs lack pigment. In the advanced stage, the hair follicles, hair bulbs, and their dermal papillae shrink and shift upward. The surrounding matrix significantly diminishes, and the connective tissue and blood vessels degenerate, with thrombosis occurring in the vessels. Over time, the number of hair follicles decreases, and the cellular infiltration becomes less noticeable.

bubble_chart Clinical Manifestations

Alopecia areata can occur at any age from infants to the elderly, but is more common in middle-aged individuals, with no significant gender difference.

This condition is often discovered accidentally or by others, with no subjective symptoms. In a few cases, there may be grade I abnormal sensations in the affected area during the initial stage [first stage] of the disease.

It begins as one or several well-defined circular or oval alopecia areata areas, with a diameter of about 1-2 cm or larger. At the edges of the alopecia areata areas, there are often some loose and easily detachable hairs, some of which have already broken off. The proximal ends of the hairs often show atrophy. If the hair is pulled out, it can be seen that the hair is thicker at the top and thinner at the bottom, resembling an exclamation mark (!), and the lower part of the hair also loses pigment. This phenomenon is a sign of the progressive stage. The alopecia areata phenomenon continues to increase, each patch also expands, and can merge to form irregular shapes. If it continues to progress, it can lead to total baldness. In severe cases, eyebrows, eyelashes, armpit hair, pubic hair, and body hair may also fall out, resulting in universal alopecia.

Alopecia areata can also stop, at which point the area of alopecia areata no longer expands, the edge hairs become more firmly attached and are not easily pulled out. After several months, the hair may gradually or rapidly regrow. Some patients may first grow white fuzz, which later thickens, darkens, and grows into normal hair.

The scalp in alopecia areata is normal, smooth, and without inflammation. Sometimes it may appear slightly thinner and concave, which is due to the disappearance of hair and hair roots, rather than actual thinning of the scalp.

Hair loss occurring at the hairline on the back of the head in children is called ophiasis.

Alopecia areata can occur simultaneously with the following diseases:

1. Nail disorders: May present as pitting, longitudinal ridges, and irregular thickening. There may also be cloudiness, brittleness, and other changes. Nail changes are more pronounced in cases of total and universal alopecia.

2. Vitiligo or white hair: About 4% of cases are accompanied by vitiligo, and new hair that grows after black hair falls out is all white. About half of the cases in Vogt-Koyanagi syndrome have alopecia areata.

3. White internal visual obstruction: May be accompanied by posterior subcapsular cataracts.

bubble_chart Treatment Measures

Encourage patients to strengthen their confidence, reduce mental burden, actively seek the disease cause and triggers, and eliminate them.

1. Systemic medication: Oral or injection of V-B₁, oral bromides or other sedatives. Corticosteroids can be used for patients with extensive lesions, total alopecia, and universal alopecia, and must be taken orally for a long time until the hair completely returns to normal. However, it is not advisable to use them in large amounts for a long time, as hair often falls out again after stopping the medication, and the side effects of hormones are already very obvious.

2. Local treatment: The exact effectiveness of various therapies is difficult to evaluate.

(1) Topical hormones and intradermal injection of triamcinolone acetonide suspension at the lesion site, 0.2～1ml each time, mixed with an equal amount of 0.5% procaine solution, once or twice a week. Some people use cow's milk for local point injection, where the milk is boiled and sterilized on the same day and then injected intradermally at points, 0.1ml per point, with a distance of 1～2cm between points, not exceeding 2ml in total each time, once a week, 10 times as a course of treatment.

(2) Drugs that stimulate local congestion such as Blister Beetle tincture, hot pepper tincture, concentrated vinegar, strong ammonia water, india mustard seed tincture, 1% minoxidil solution, etc. Chinese medicine's plum blossom needle tapping.

(3) Local physiotherapy tuina, ultraviolet irradiation, resonance spark therapy, audio frequency electrotherapy, etc.

(4) Tissue therapy: Tissue embedding, local embedding of catgut, or intramuscular injection of placental tissue fluid, etc.

3. Chinese medicine Chinese medicinals: There are reports that Shouwu Hair Growth Drink and Hair Growth Tincture have good effects.

bubble_chart Prognosis

Generally, patients with mild conditions have a better prognosis and may gradually or quickly grow fine, soft, yellowish-white vellus hair, which will eventually thicken, darken, and return to normal. Typically, one or two patches of alopecia areata on the occipital region without significant progression are more likely to resolve on their own. Patients with severe conditions have a poorer prognosis. Complete hair loss in children is more difficult to recover from, although there are cases where recovery occurs after 20 to 30 years. About half of the cases may recur, especially in children, who are also more prone to developing complete hair loss.

bubble_chart Differentiation

According to the sudden onset, circular or oval alopecia areata, the scalp in the alopecia areata area is normal, making it not difficult to diagnose. It must be differentiated from the following diseases:

1. Tinea capitis (white ringworm) - Incomplete hair loss, most hairs are broken, residual hair roots are not easily pulled out, and scales are attached. Fungi are easily found in the broken hairs. It is common in children.

2. Syphilitic alopecia - Although it also presents as patchy hair loss without scar formation, the edges are irregular and moth-eaten. The alopecia areata areas are also incomplete, numerous, and commonly occur on the posterior side. Accompanied by other syphilis symptoms, syphilis serology tests are positive.

3. Pseudopelade - The affected scalp is atrophic, smooth, and shiny, with no visible hair follicle openings, and the edges of the patches do not show the characteristic "exclamation mark" hairs of alopecia areata.