LAFORAS-DISEASE IN SOUTH-INDIA - A CLINICAL, ELECTROPHYSIOLOGIC, AND PATHOLOGICAL-STUDY

Twenty-one cases (12 males, 9 females) of Lafora's disease in 16 famil ies were studied at the National Institute of Mental Health and Neuro Sciences (NIMHANS), Bangalore, India, from 1982 to 1990. Mean age of o nset was 13.5 years (range 9.5-18 years). First symptom was generalize d tonic-clonic seizure (17), myoclonus (3), or dementia (1). All patie nts eventually developed the classical triad, except 1 who has had onl y myoclonus. Seven had occipital seizures. Other signs included behavi oral changes (9), brisk tendon reflexes (11), cerebellar signs (8), an d visual impairment (4). Patients from 14 of the 16 families (85%) wer e products of consanguineous marriage. More than 1 sibling was affecte d in 6 families. Scalp EEGs showed diffuse background slowing with epi leptiform discharges in all and progressive slowing as the disease pro gressed 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 soma tosensory evoked potentials (SSEP) were observed in all 8 cases studie d. 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 negat ive. In the brain, inclusions were evident in glial and capillary endo thelial 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 recess ive inheritance. The high frequency of consanguinity in the South Indi an population may be responsible for the many cases observed at our ce nter.