Correlation Between Loss of Pin Sensation and Epidermal Axons

Researchers report high clinicopathologic correlation between distal loss of pin sensation and of axons, confirming the utility of pin exam for SFN diagnosis.

Neurologists focus on diseases of myelinated axons because we lack tools to see the unmyelinated and thinly myelinated small fibers whose degeneration causes chronic pain in small-fiber neuropathy (SFN). Electromyography and nerve conduction velocity testing (EMG/NCV) are insensitive to small-fiber action potentials, and nerve biopsies risk complications, including neuralgia (Diabet Med 1997; 145:353). When chronic pain is the sole symptom and EMG/NCV results are normal, few physicians are comfortable prescribing pain medications based on clinical impression alone.

University of Minnesota and Johns Hopkins nerve specialists previously developed an alternative test: skin biopsies immunolabeled to reveal intracutaneous axons (Neurology 1999; 5…

Reviewing Author

Anne Louise Oaklander, MD, PhD