Previous studies have demonstrated that, with the exception of atracurium, resistance to the neuromuscular blocking effects of various muscle relaxants develops in patients receiving anticonvulsant therapy. We studied the effects of 0.5 mg/kg IV atracurium in 53 neurosurgical patients: 21 nonepileptic patients receiving no anticonvulsant therapy (MED = 0); 14 epileptic patients treated with carbamazepine for years (MED = 1); and 18 epileptic patients treated with carbamazepine plus either phenytoin or valproic acid for years (MED = 2). The evoked compound electromyogram of the adductor pollicis brevis was recorded, and results were analyzed using analysis of covariance, with weight and age as covariables. The onset time was not significantly different among the three groups. Times for recovery of baseline and train-of-four responses to stimuli were significantly shorter in the MED = 1 and MED = 2 groups than in control patients (MED = 0). The recovery index (time between 25% and 75% recovery of baseline electromyogram values) was progressively shorter in the three groups (MED = 0: 8.02 min; MED = 1: 5.93 min; MED = 2: 1.96 min; P less than 0.001). This study demonstrates that atracurium, when used on epileptic patients requiring long-term (that is, years of) anticonvulsant therapy, has a shorter duration of action than when used in nonepileptic patients.

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Vasospasm that occurs after subarachnoid hemorrhage (SAH), despite successful surgical or radiological intervention remains with an ominous prognostic recovery period. 1 We investigated the correlation of S100B protein in CSF and serum with incident of vasospasm and neurological outcome in patients undergoing intracerebral aneurysm clipping. Twenty five patients were enrolled. All patients received combined anesthetic techniques. Brain protection was provided by isoflurane. A CSF sample (2 cc) and blood sample (5 cc) were drawn 3 times (before skin incision, 30 minutes and 24 hours after clipping). Patients were followed for the incidence of vasospasm in Neurosurgical Intensive Care Unit and the neurological status at discharged was assessed using Glasgow Outcome Scale. Compared with baseline level (at 0 minute) we found that early changes in CSF S100 B level at 30 minutes significantly correlate with vasospasm (P = 0.005, sensitivity 90% and specificity 90%) but the correlation dissipated at 24 hours. In addition, early changes in S100B in CSF at 30 minutes significantly correlate with neurological outcome (P = 0.003). The relationship persisted at 24 hours (P , 0.011). In Serum we found no significant correlation between S100B at 30 minutes or 24 hours with either vasospasm or neurological outcome. We conclude that changes of S100B level in CSF in patients undergoing intracerebral aneurysm clipping surgery are strongly correlated with vasospasm and can be a reliable diagnostic tool to identified patients who are endangered with evolving vasospasm after a successful securing aneurysm surgery. Reference: 1. Pluta RM. Delayed cerebral vasospasm and nitric oxide: review, new hypothesid, and proposed treatment.