The case of the focal alopecia. The what?

A focal hair loss. You will see this if you look for it. You will also gain insight into what is (or may be) going on.

Take a good look at these pix. Notice anything about the left anterior lower leg? Besides the varicosity, did you notice the absence of hair? Look again. The devil is in the details, eh?

So, is this a Nair experiment gone wild? No, he never touches the stuff

Shaves just one part of his leg? Really? NOT!

Bad burn resulting in follicular damage? Nice thought, but no.

Weird infection or food allergy? Another good thought but no.

OK. I give up.

So you need to ask the patient a question, what is it?

Do you have a history of chronic low back pain?


Where do you think the problem may be coming from?

Take a look at the dermatomal diagram at the bottom. It represents the area of skin innervated by a spinal nerve. Looks like L5 to us.

How can we confirm it?

muscle test predominantly L5 innervated muscles like the long extensors of the toes and gluteus medius. You could also x ray and look for degenerative changes at the L4-L5 level. Flexion/extension films may reveal some instability at this level as well.

Why does it happen?

Hair growth is influenced by local blood flow and “tropic” influences from the autonomic nervous system and sensory feedback loops, supplied to the area segmentally (ie. by each spinal level). This can be traced back to embryology and development of the musculoskeletal system via the somite and their individual sclerotome (connective tissue elements), dermatome (skin elements) and myotome(muscular elements).

How could this influence his gait?

weakness of the L5 innervated muscles possibly causing:

  • crossover gait
  • lean to one side during stance phase
  • pelvic “cruise” to one side during stance phase on  that limb
  • foot drop and steppage gait (lifting the limb higher on one side to get the foot to clear)

Details, details, details. Pay attention and look carefully. It is all right there if you look hard enough.

The Gait Guys. Balding, yet still neurologically intact