How is small fiber neuropathy diagnosed? i understand that a negative emg is common with this disorder, actually a hallmark of it.

Diagnosing N injury: Small fiber neuropathy begins symptoms with loss of vibration or temperature sensation but may not be measured on EMG as that test does not pick up these small fibers. The tests are a good h&p, vibratory, single fiber, and pulse exam.

A few comments: The EMG tests large fibers only. Small fiber neuropathy can only be fully confirmed by a skin punch biopsy, but allows better confirmation of diagnosis. Typically, presents with pain and numbness. Decreased pin and temperature sensations may give clues to presence. Recommend this be managed by experienced neurologist, as this area is indeed a frontier of medicine.

Autonomic or skin: The traditional test for a small fiber neuropathy is an epidermal biopsy, which can be done in the doctors office in about 10 minutes. In this test, two small punch biopsies are taken from the calf and the thigh, and sent off to count the number of nerve fibers in the epidermis. Autonomic testing (looking for change in blood pressure with position, etc) can also be used.