Onset: may be subtle, ranging from childhood to mid-adult
Ocular and cranial nerve findings:
(1) retinitis pigmentosa
(2) neurogenic hearing loss
(3) anosmia
(4) abnormal pupillary response
(5) miosis
(6) night blindness
(7) decrease in visual acuity and contraction in visual fields progressing to blindness
(8) cataract
Findings in the extremities:
(1) peripheral polyneuropathy, mixed motor and sensory (loss of deep tendon reflexes, paresthesias, anesthesias, dysesthesias, weakness)
(2) marked muscular atrophy
(3) skeletal abnormalities (involving metacarpals, metatarsals, knees, elbows, shoulders)
(4) cerebellar findings which may include ataxic gait or intention tremor
Other findings:
(1) cardiomyopathy with risk of sudden death
(2) ichthyosis
Laboratory findings:
(1) increased concentration of plasma phytanic acid
(2) CSF protein concentration elevated without pleocytosis (albuminocytologic dissociation, total protein >= 100 mg/dL)
Diagnostic tetrad:
(1) retinitis pigmentosa
(2) peripheral polyneuropathy
(3) cerebellar ataxia
(4) high CSF protein
