The Norwood Scale or Norwood-Hamilton Scale is a scale/chart designed to classify the degrees of male pattern baldness.
Dr. James Hamilton was the first to record the different degrees of male pattern baldness in the 1950s. He looked at male pattern hair loss as it advances, and identified several patterns of it. Hamilton was very successful in classifying the degrees of male hair loss.
A hair transplant surgeon Dr. O’Tar Norwood (also a dermatologist), revised Dr. Hamilton’s Hamilton scale in 1975. Dr. Norwood studied the hair loss patterns in 1,000 males. He then added more patterns to Dr. Hamilton’s scale. The new scale goes by the name Norwood Hamilton Scale and sometimes Hamilton Norwood Scale. It joins the two interpretations by Hamilton and Norwood.
The Norwood Hamilton Scale for baldness is very successful in identifying the level of hair loss in men. It is an accepted standard to measure the extent of hair loss.
The modified scale can determine the grade of hair loss according to the following types/patterns of hair loss in men:
Norwood Hamilton Scale Types of Hair Loss:
Stage/Type I (Pattern I): No recession or minor recession of the hairline. No requirement for any treatment. In the case of family history of baldness, close monitoring is a good idea.
Stage/Type II: The front temporal hairline has symmetrically receded. The receding shape is triangular. Can be a sign of more significant hair loss in the future.
Stage/Type III: The temples have symmetrical recession. In Stage III vertex, the crown also loses hair with age. Type III is considered to be sufficient to be named as baldness in the Norwood Hamilton Scale.
Stage/Type IV: Severe hair loss in the frontotemporal (frontal hairline and temporal area) areas. More severe than in Type III. There no hair on the vertex (or perhaps the hair is sparse on the vertex.) There is hair loss on the crown.
Stage/Type V: Larger hair loss at the vertex and the frontotemporal regions. The vertex hair loss region is still separated from the frontal hairline recession. Looks like a horseshoe shape from above.
Stage/Type VI: Sparse hair in the bridge of hair that crosses the crown. Significant hair loss. The frontotemporal area and the vertex area are now one. More hair loss.
Stage/Type VII: advanced and severe hair loss. Very little hair on the scalp. The remaining hair on the back of the scalp is thinner than before. Sparse hair with a semi circle over the ears. Very significant hair loss.
Norwood Type/Class A
What characterizes class A is the front to back progression of baldness. These are different to the other Norwood types on the scale. In these patterns, the crown has little hair loss compared to the scale. There is no connecting bridge on the top of the scalp.
These are rare patterns. And yet, as the recession is significant on the front of the scalp, affected patients can look bald. If you are suffering from class A type hair loss, you can be a perfect candidate for hair restoration/transplantation.
Your doctor can identify your hair loss pattern according to the Norwood scale, and this will help in choosing the right treatment for you.