[Metachromatic leukodystrophy: an exceptional cause of dementia in the adult].

Hereditary metabolic diseases are an exceptional cause of neurological disorders in adults. Metachromatic leukodystrophy is a hereditary alteration of the metabolism of myelin which may be manifested in adults as intellectual deterioration. A case of metachromatic leukodystrophy presented in adulthood is presented with cognitive deterioration and behavioral alterations as the only clinical manifestation. The patient was a 28 year old male studied for dementia of one year of evolution. Computerized tomography and cranial magnetic resonance demonstrated diffuse and symmetric involvement of the periventricular white matter. The visual evoked potentials were involved while the brain stem auditory potentials were normal. Study of the speed of nerve conductions was compatible with demyelinating neuropathy. The diagnosis of metachromatic leukodystrophy was confirmed by enzyme study revealing very diminished levels of aryl-sulfatase A. Although it is exceptional the adult form of metachromatic leukodystrophy should be included in the differential diagnosis of dementia. Computerized tomography and cranial magnetic resonance together with neurophysiologic studies are the principle procedures orienting diagnosis to this disease.