We report the case of a 34-year old man, who, after presenting with subacute traumatic subdural haematoma, was diagnosed as CTX. He presented a ten year history of progressive deterioration of cognitive functions, unsteadiness of gait and surgery for bilateral cataracts at age 21. Cholestanol level in serum was 120.7 mmol/liter, and cholestanol/cholesterol ratio 2.52%. Bile alcohols in urine were 23, 25-pentol: 2.2665 mg/mmol creatinine, 24, 25-pentol: 1.3226 mg/mmol creatinine, and 27-nor-24, 25-pentol: 0.7363 mg/mmol creatinine. Electrophysiological study was consistent with a mixed demyelinating and axonal neuropathy. The assessment of autonomic nervous system (ANS) showed a postganglionic cholinergic failure accompanying somatic peripheral neuropathy. Brain-stem auditory evoked potentials (BAEPs) demonstrated markedly low amplitude and poorly defined waves, and almost symmetrical peak V and I to V interpeak latency (IPL) slight delays. Two nodular, bilateral, symmetrical lesions, strongly suggestive of calcifications, in the cerebellar white matter on CT and MRI were noted. On T2-weighted images diffuse high signal lesions were found in the cerebellar white matter, and multiple, hyperintense cerebral foci of demyelination or gliosis. MRI study of the Achilles tendon showed neither enlargement of the tendon, nor areas of lipid deposits. After ten months of treatment with chenodeoxycholic acid (CDCA) (750 mg/d) the clinical course was unaffected and the neurophysiological measures, CT and MRI remained unchanged.