BACKGROUND—Striatal necrosis has been related to various clinical syndromes, with acute or chronic progression, and juvenile or late occurrence, but the most common type is Leigh's encephalopathy. METHODS—Between 1967 and 1995, six out of seven related patients with chronic familial dystonia were examined. MRIs were performed in four, between 1992-1994. The seven members, affected over three generations, were the father, three daughters (one surviving), and three surviving grandsons. RESULTS—The leading symptoms were gait disorders and dystonia in all, dysarthria in six, verbal and motor stereotypies in two, and parkinsonian and cerebellar signs in three. Optic neuropathy was found in three. A frontal lobe syndrome without amnesia occurred in two. Symptoms occurred between the second and the fifth decade, with progressive deterioration. Magnetic resonance imaging, performed in four, showed in the two patients with severe neurological signs diffuse striatopallidal abnormal hyposignal (comparable with CSF signal) in T1 weighted images, suggesting extensive necrosis of the striatum and pallidum, associated with thalamo-subthalamo-rubro-dentato-nigral and substantia innominata hypersignals in T2 weighted images suggesting gliosis in these respective areas. The same images were described to a lesser extent in a third patient. Concentrations of lactate in CSF and serum were normal in three. Muscle biopsy, performed in four, was shown to be normal. Enzyme histochemistry showed complex I, III, and IV deficiency in surviving patients. CONCLUSION—This familial dystonia of chronic progression may be related to basal ganglia necrosis or gliosis, associated with alterations in the respiratory chain. These metabolic alterations probably play a part in the pathophysiology of these unusual brain lesions.