Case presentation
The patient was an elderly man in his 80s, 148 cm tall, weighing 50.0 kg, who presented to a nearby clinic with discomfort in the inguinal region. Further investigation led to a diagnosis of extramammary Paget’s disease, for which surgical excision under general anesthesia was planned. The patient had a medical history of hypertension and asymptomatic cerebral infarction and was on aspirin. He had no significant family history. Electrocardiography revealed complete right bundle branch block, and blood tests did not show any notable abnormalities.
Anesthesia induction was performed with propofol 60 mg, fentanyl 100 µg, remifentanil 0.1 µg/kg/min, and rocuronium 50 mg. Maintenance of anesthesia was achieved using sevoflurane 1%, remifentanil at a rate of 0.1-0.15 µg/kg/min, and intermittent administration of rocuronium 10 mg. An 8 mm endotracheal tube was used for intubation. Intraoperatively, the patient’s hemodynamics and oxygenation were stable without any significant abnormalities. Brain function monitoring to assess sedation levels was not performed intraoperatively, was not used to assess sedation levels. The surgery lasted for 2 hours and 49 minutes. The surgical procedure was completed uneventfully, following which administration of anesthesia was discontinued. When the end-tidal concentration of sevoflurane reached 0.1-0.2%, the patient was awakened, and eye opening was observed. After confirming the patient’s consciousness, sugammadex was administered, and extubation was performed. A few minutes after extubation, the patient’s level of consciousness was observed to decrease, subsequently reaching a Glasgow Coma Scale (GCS) score of E1V1M1. His respiratory status remained stable. Considering the possibility of the effect of residual opioids, naloxone was administered, but with no change in the level of consciousness. His body temperature was 37.0 ℃. Prompt blood gas analysis was performed, which revealed normal pH and electrolyte levels. There were no signs of hypoglycemia (blood sugar 110mg/dL), and no specific findings to explain the decrease in consciousness level. However, due to the emergence of right conjugate eye deviation, further investigations were conducted to evaluate for an intracranial pathology. Both head computed tomography and magnetic resonance imaging scans were performed, but no abnormal findings, such as new brain infarctions or intracranial hemorrhage, were detected (Figures 1 and 2). Since there were no respiratory or circulatory abnormalities, re-intubation was not performed. Preoperative systolic blood pressure was around 120 mmHg, and intraoperative systolic blood pressure remained at 100-130 mmHg. The patient was urgently transferred to the intensive care unit (ICU) for close observation. Approximately one hour after admission to the ICU, the patient developed involuntary movements in the left upper limb, suggestive of a seizure. Based on the assumption of an epileptic seizure, 5 mg of diazepam was administered, which resulted in an improvement in the level of consciousness (GCS E4V5M6). No further obvious neurological abnormalities were observed. Subsequently, levetiracetam administration was initiated from the first day after surgery. Electroencephalography (EEG) performed on the second day after surgery showed minimal significant findings. No seizures occurred thereafter, and the patient was discharged on the 16th day after surgery without any neurological complications.