Background: Intraoperative seizures are rarely reported in extracranial surgeries, especially in patients with no known history of seizures. We report a case of new onset status epilepticus in a patient undergoing spine surgery under total intravenous general anesthesia.
Case Description: A 60-year-old male with history of hypertension, anxiety, and biopsy proven prostate cancer, initially presented with progressive lower extremity numbness and weakness. His work up on admission included an MRI of his spine showing a pathologic compression fracture of T7 with an infiltrating epidural tumor causing moderate compression of the spinal cord. Patient was scheduled for T7 laminectomy, transpedicular decompression, and T5-T9 posterior lumbar interspinal fusion. The surgical team planned to monitor SSEPs and MEPs, therefore a total intravenous anesthetic was planned. Premedication with Midazolam was given prior to transport to the operating room. General anesthesia was induced with Fentanyl, Lidocaine, Propofol, and Succinylcholine. Patient was intubated and mechanically ventilated with tidal volumes of 500 ml and end tidal CO2 values of 32-34 mmHg. Total intravenous anesthesia was started with Propofol and Remifentanil. Immediately post-incision, propofol was uptitrated to 150 mcg/kg/min and remifentanil was increased to 0.3 mcg/kg/min and then to 0.4 mcg/kg/min. Patient tolerated incision well and remained stable for the beginning portions of the procedure. Approximately 90 minutes after induction of anesthesia, patient started showing seizure activity on EEG. No visible convulsions were noted. Additional propofol bolus was given along with Midazolam. Seizure activity persisted, so further antiepileptics of Phenytoin and Levetiracetam were given. No medications administered were able to place the patient into burst suppression. A decision was made to start pentobarbital and burst suppression was finally achieved. Discussion with the surgical team occurred and the procedure was aborted. Patient was transferred to the neurosurgical ICU and placed on continuous EEG. MRI brain with contrast was completed to investigate etiology of seizures and showed at least 5 small enhancing foci in the cerebrum and cerebellum. Patient remained on midazolam drip for 5 days along with multiple antiepileptics. Once seizure activity diminished, midazolam was fully weaned. Patient awoke and was extubated 6 days post procedure. He was transitioned to hospice care.
Discussion: While intraoperative seizures under general anesthesia are a rare occurrence, prompt diagnosis and treatment are prudent to avoid long term neurological complications. Preoperative evaluation should focus on risk factors for neurologic sequelae. In this patient, with known metastatic cancer, no preoperative brain imaging was completed. The likely etiology of his seizure activity was his later discovered brain metastases. The treatment of status epilepticus intraoperatively should focus on burst suppression. In this case, both propofol and midazolam were not sufficient. Treatment was escalated to add further antiepileptic agents, with pentobarbital finally placing patient into burst suppression. The immediate recognition and treatment of his seizure activity enabled full recovery from seizures and no apparent neurologic deficits upon awakening.
