Lafora's disease in south India: a clinical, electrophysiologic, and pathologic study.

Twenty-one cases (12 males, 9 females) of Lafora's disease in 16 families were studied at the National Institute of Mental Health and Neuro Sciences (NIMHANS), Bangalore, India, from 1982 to 1990. Mean age of onset was 13.5 years (range 9.5-18 years). First symptom was generalized tonic-clonic seizure (17), myoclonus (3), or dementia (1). All patients eventually developed the classical triad, except 1 who has had only myoclonus. Seven had occipital seizures. Other signs included behavioral changes (9), brisk tendon reflexes (11), cerebellar signs (8), and visual impairment (4). Patients from 14 of the 16 families (85%) were products of consanguineous marriage. More than 1 sibling was affected in 6 families. Scalp EEGs showed diffuse background slowing with epileptiform discharges in all and progressive slowing as the disease progressed in 3. Photosensitivity occurred in 4 of the 17 cases studied (23.5%). EEG abnormalities were documented in the presymptomatic stage in 2 cases 6 months and 6 years before clinical symptom onset. Visual evoked responses were abnormal in 4 of the 6 cases studied. Giant somatosensory evoked potentials (SSEP) were observed in all 8 cases studied. Lafora bodies were demonstrated in axillary skin in 14 of 17 (82.4%), in liver in 4 of 10 (40%), and in both brain biopsy specimens. In 2 cases, liver biopsy was positive while axillary skin biopsy was negative. In the brain, inclusions were evident in glial and capillary endothelial cells in addition to neurons. Although our cases were similar to those described earlier, the relative rarity of visual phenomena is emphasized. The clinical pattern was consistent with autosomal recessive inheritance. The high frequency of consanguinity in the South Indian population may be responsible for the many cases observed at our center.