IMPAIRMENT OF CONSCIOUSNESS INDUCED BY VALPROATE TREATMENT FOLLOWING NEUROSURGICAL OPERATION

Eight patients, who underwent neurosurgery for various supratentorial lesions presented unexplained impairment of consciousness during the f irst post-operative days. These states ranged from stupor to deep coma , and two patients had an emergency re-exploration. All these patients were receiving the usual dosage (1000 to 1500 mg per day) of Valproic acid (VPA). The treatment had been initiated either several weeks or months previously in 4 cases, and was thus well tolerated, or the day before surgery in the 4 other cases. EEG recordings displayed diffuse abnormalities, delta waves and/or high voltage triphasic complexes, th at led to the diagnosis of VPA intolerance and drug withdrawal. Then f ull clinical recovery and EEG clearing occurred within 1 to 5 days. VP A intolerances are welknown but remain exceptional, about 1 case per 1 00.000. In our neurosurgical population, however, the rate was higher, approximately 2%. Wide areas of blood brain barrier destruction may c ontribute to the higher frequency of this easily reversible cause of p ost-operative stupor or coma.