The Norwood male pattern baldness classification system
Male pattern baldness is often diagnosed with the help of a classification system using diagrammatic representations of progressively more extensive hair loss. Originally designed by Hamilton in the 1950s the pattern baldness classification system was modified to its current form by Norwood in the 1970s. Norwood also added grades IIIa, III vertex, IVa and Va to Hamilton's original classification scale.
There are now seven recognized categories of male androgenetic alopecia along with various subtypes based on Norwood's classification system. Frequently when consulting with a dermatologist the diagnosis of androgenetic alopecia will be made in reference to the classification and you will be given your subclass such as “type III” or similar. These classification scales are used extensively in monitoring treatment trials.
Norwood's basic scale is described and illustrated below. Norwood's variant scale is described elsewhere.
Type I. Minimal or no recession of the hair line.
Type II. Triangular, usually symmetrical, areas of recession at the frontotemporal hair line.
Type III. This represents the minimal extent of hair loss sufficient to be considered as baldness according to Norwood. Most type III scalps have deep symmetrical recession at the temples that are bare or only sparsely covered by hair.
Type III vertex. In this presentation, the hair loss is primarily from the vertex with limited recession of the frontotemporal hair line that does not exceed the degree of recession seen in type III.
Type IV. The frontotemporal recession is more severe than in type III. There is sparse hair or no hair on the vertex. The two areas of hair loss are separated by a band of moderately dense hair that extends across the top. This band connects with the fully haired fringe on the sides of the scalp. Type IV is distinguished from type III vertex in which the loss is primarily from the vertex.
Type V. The vertex hair loss region is still separated from the frontotemporal region but it is less distinct. The band of hair across the crown is narrower and sparser. The vertex and frontotemporal regions of hair loss are bigger. Viewed from above, types V, VI, and VII are all characterized by surviving hair on the sides and back of the scalp forming a distinct horseshoe shape.
Type VI. The bridge of hair that crossed the crown is now gone with only sparse hair remaining. The fronttemporal and vertex regions are now joined together and the extent of hair loss is greater.
Type VII. The most severe form of hair loss presents as extensive loss. A narrow band of of hair in a horseshoe shapes survives on the sides and back of the scalp. This hair is usually not dense and may be quite fine. The hair is also sparse on the nape of the neck and in a semi circle over both ears.
