Article
Microdialysis findings in a patient with refractory generalized non-convulsive status epilepticus
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Published: | June 9, 2017 |
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Objective: Microdialysis has primarily been used in patients and models with subarachnoid hemorrhage or traumatic brain injury. Little is known about brain metabolism during epileptic seizures.
Methods: In this case report a 52-year-old female with a primary onset of a tonic-clonic seizure and consecutive status epilepticus was transmitted to our neurosurgical ICU. The EEG of the now intubated and analgosedated patient showed a persisting status epilepticus which was non-convulsive and refractory to midazolam, levetiracetam, lacosamid and phenytoin. Due to a cerebral edema visible on MRI scans an ICP probe as well as a microdialysis catheter were implanted with a combined bolt into the right frontal lobe. Extracellular microdialysis samples were collected hourly for the following five days.
Results: Initial glutamate and pyruvate levels were markedly elevated up to 98 µM and 385 µM, respectively, while the lactate-pyruvate-ratio was within normal limits. After initiation of a continuous intravenous thiopental therapy glutamate levels dropped despite a persisting status epilepticus on EEG monitoring. A burst suppression encephalogram was achieved after a fractionated bolus application of thiopental. The microdialysis samples now revealed decreasing levels of both, glutamate and pyruvate. However, both increased again during the course of time. Concurrently, the EEG revealed a reoccurring status epilepticus pattern. After reapplying 750 mg fractionated thiopental a sustained burst suppression pattern was achieved. Subsequently, glutamate decreased from 79 µM to normal levels below 30 µM within 24 hours. Also, pyruvate further decreased, still showing a normal lactate-pyruvate-ratio. Glucose was within a normal range over the whole course of disease.
Conclusion: The elevated cerebral pyruvate levels but normal lactate-pyruvate-ratios during a refractory non-convulsive status epilepticus in the reported case might reveal an increased metabolism but preserved perfusion and mitochondrial function. Extracellular glutamate levels, indicating excitotoxicity, already decreased before achieving burst suppression. Microdialysis might be a useful additional diagnostic tool in neurointensive therapy of refractory status epilepticus.