Valproate induced non hepatic hyperammonaemic encephalopathy (VNHE)--a study from tertiary care referral university hospital, north India.

OBJECTIVE: To report and discuss twelve cases of Valproate (VPA) induced hyperammonaemic encephalopathy without liver failure in subjects receiving VPA therapy.

METHODS: This study was conducted in the department of Neurology, G.B. Pant Hospital, New Delhi from January 2000 to December 2006. The subjects were on treatment with VPA alone or in combination with other anti epileptic drugs and developed symptoms of encephalopathy. The data collected included the type of epilepsy, the dose of VPA and other co-administered anti epileptic drugs (AED), their serum levels, clinical presentation, relevant radiological and laboratory investigations, serum ammonia levels, the measures taken to treat the patient and their outcome.

RESULTS: A total of twelve cases of VPA induced Non hepatic hyperammonemic encephalopathy (VNHE) were studied, out of which six were males and six females. The age ranged from 2-75 years with mean age of 21.33 +/- 20.84 years. Four subjects were on VPA alone and the others were also on concomitant AEDs. All the above subjects presented with either confusion or altered sensorium (100%). None of the subjects had any other demonstrable cause of encephalopathy. The serum ammonia level in these subjects ranged from 77.3-345 micromol/L with mean of 163.98 micromol/L +/- 48.67 (normal range 10-47 micromol/L). The serum VPA level in this study group ranged from 63-132.6 microg/ml with mean of 93.44 microg/ml +/- 31.77 (normal range 50-100 microg/ml).

CONCLUSIONS: In any patient on VPA therapy, who develops signs and symptoms suggestive of encephalopathy, even in the presence of normal liver function, VNHE should be suspected. Fortunately, it has a good prognosis and the early withdrawl of VPA leads to improvement in almost all cases.