The sural nerve in familial dysautonomia.

In familial dysautonomia there are malfunctions of motor, sensory and autonomic systems. The sural nerve has reduced transverse fascicular area, diminished numbers of myelinated axons (particularly those of small diameter) and very few non-myelinated axons. Catecholamine containing endings are not found in accompanying arteries. These changes are compatible with reduced neuronal populations described in sympathetic and sensory ganglia. The observed pathology accounts for many of the clinical features of the disease and suggests an abnormality in intrauterine development.