Familial spastic paraplegia with mental impairment and thin corpus callosum.

We described four patients in two families of unique familial spastic paraplegia (FSP) which was thought to be possibly autosomal recessive inheritance. All four patients had quite similar manifestations. Gait disturbance started at their second decade, then spastic paraparesis and mental deterioration progressed slowly. Cerebellar ataxia and sensory loss in the distal parts of four extremities were also slightly presented. In all patients, cranial MRI revealed marked thin corpus callosum with mild changes in the region of periventricular white matter and in the gray matter. Biopsied sural nerves of all patients showed chronic axonal degeneration with mild decrease of both large and small myelinated fibers. Electron microscopic study demonstrated crystalline-like inclusion bodies in the cytoplasm of Schwann cells in all patients. Despite extensive investigation for metabolic disorder, we could not find any abnormality. However an etiology have not established at the time presented, the combination of these clinical features suggested that the disorder could represent a specific clinical entity.