Male pattern baldness

the most common form of hair loss in men is known as male androgentic alopecia , affecting 30-­50% of men age 50. It occurs in a highly reseeding pattern, affecting the temples, mid frontal scalp and vertex region. hair loss impacts self­image as well as great cause of anxiety and depression in some men. The characteristics of male androgentic alopecia are changes in hair cycle development, follicular miniaturization and inflammation. The duration of anagen phase ( hair grow phase) decreases with each cycle, while the length of telogen phase is prolonged. Ultimately, anagen duration becomes so short the growing hair fails to achieve sufficient length, leaving an empty follicular pore.

While many men choose not to go for treatment, topical minoxidil and oral finasteride are approved for the treatment of Male androgenetic alopecia. Both medications prevent hair loss, but only partially reverse baldness, and require continuous use to maintain the effect. Topical anti­androgens, antifungals, growth factors, and laser treatment are all emerging medical treatments for Male Androgenitic Alopecia. Hair transplantation involves removal of hair from the occipital scalp and implantation into the bald vertex and frontal scalp. With modern techniques, graft survival rate is 90% can be achieved. A combination of these therapeutic options is now available for men experiencing male androgenetic alopecia. Hair transplantation is widely practising in the USA and takes advantage of the relative androgen­resistant donor occipital hairs.

Genetics and Androgenetic Alopecia

A familial tendency to Male Androgenic Alopecia is well recognized. The baldness gene behaved in an autosomal dominant manner in men. A bimodal distribution of phenotypes usually seen in autosomal dominant disorders. The phenotypes seem to follow a normal distribution in men and women. This, findings increase the risk of baldness with the number of affected family members. Polygenic diseases are much more common, as is the case with androgenetic alopecia.

The current concept of polygenic inheritance is supported by an Australian study that examined the of the 54 father-­son relationships, 81% of balding sons had fathers who had significant balding. The male pattern baldness with a polymorphism of the androgen receptor gene which are present on the X chromosome.

However the role of the 5 alpha reductase enzyme in Male androgenetic alopecia is responsible the metabolism of testosterone to dihydrotestosterone.

Hormonal and androgenic alopecia

Hair growth begins under the skin in structures, which called as follicle. Hair grows normally from 2 to 6 years, goes into a resting phase for several months, and then falls off. The cycle starts over when the follicle begins growing a new hair. Increased levels of androgens in hair follicles can lead to a shorter the cycle of hair growth and thinning of hairs. 

Norwood classification

Type I: There is minimal or no reseeding of the hairline.
Type II: There are triangular, usually symmetrical, areas of hairloss at the frontotemporal hairline.
Type III: This represents the minimal hair loss sufficient to be considered as baldness according to Norwood. There are deep symmetrical hair loss at the temples that are bare or only sparsely covered by hair. In Type III vertex, the hair loss is primarily from the vertex with limited hair loss of the frontotemporal hairline that does not exceeds the degree of air loss seen in Type III.
Type IV: The frontotemporal hair loss is more severe than in Type III and there is no hair on the vertex.
Type V: The vertex hair loss region is separated from the frontotemporal region but less distinct. The band of hair across the crown is narrower, the vertex and frontotemporal regions of hair loss are bigger.
Type VI: The front to temporal a and vertex regions are joined together and the hair loss is greater
Type VII: This hair is usually not dense and may be quite fine and short

The various Type A variants described by Norwood are as follows:

Type IIA: The hairline is anterior to the coronal plane 2 cms anterior to the external auditory meatus.
Type IIIA: The hairline will receded back to a point between the limit of Type IIA and level of external
auditory meatus.
Type IVA: The hairline has receded beyond the external auditory meatus but it wont reached the vertex.
Type VA: The area of denudation which includes the vertex. Hair loss more severe than Type VA cannot
be distinguished from Types VI or VII.