On medical imaging, the nerves of the extremities (and cranial nerves in some cases) appear enlarged due to hypertrophy of the connective interstitial tissue, giving the nerves a distinct "onion-bulb" appearance. Peripheral (and possibly cranial) nerve excitability and conduction speed are reduced.
Dejerine–Sottas disease
Nicolau–Balus syndrome
Madras motor neuron disease
Parkes Weber syndrome
Stratton Parker syndrome
Neu–Laxova syndrome
Satoyoshi syndrome
Brown–Vialetto–Van Laere syndrome