Vasomotor instability and sensory neuropathy are among the outstanding signs in familial dysautonomia. Episodic hypertension alternating with hypotension, hyperhidrosis, cyclic vomiting, and skin blotching are common. Deep tendon reflexes are often diminished or absent and there is a general indifference to pain and temperature. The lingual fungiform papillae are missing resulting in taste disturbances. Emotional instability and impaired coordination are frequently seen. Emotional or physical stress can precipitate dysautonomic crises with nausea, vomiting, agitation, tachycardia, and hypertension. Physical growth may be slow and scoliosis is common. Patients are susceptible to self-injury.
Arrested development in the sensory and autonomic nervous systems results in a reduction in nonmyelinated nerve fibers as well as a reduction in small diameter myelinated axons. Sympathetic ganglia are abnormally small in size. There is hypersensitivity to both sympathomimetic and parasympathomimetic drugs.