Navigating Anaesthetic Complexities in Perimesencephalic Epidermoid Cyst with Obstructive Hydrocephalus: A Case Report

Perimesencephalic epidermoid cysts are rare intracranial lesions that present with atypical neurological symptoms caused by obstructive hydrocephalus. This case report details the complex neuro-anaesthetic management of a 53-year-old male {Body Mass Index (BMI) 26.6} who presented with altered sensorium, vomiting, tinnitus, and headache for one week. Neurological assessment showed a Glasgow Coma Scale (GCS) of E3V4M5, with the involvement of cranial nerves VIII–X and disorientation. An MRI of the brain (plain) revealed a perimesencephalic epidermoid cyst measuring 4.2×1.6×2.1 cm, accompanied by obstructive hydrocephalus. The anaesthetic plan involved a staged approach: External Ventricular Drainage (EVD) followed by definitive tumour excision in the left lateral sitting position. The patient, classified as ASA Grade III, had stable cardiovascular status but exhibited a potentially difficult airway (Mallampati class III). Intraoperative management included invasive monitoring through radial artery and central venous catheterisation, controlling Intracranial Pressure (ICP) using mannitol, a scalp block for analgesia, and the avoidance of nitrous oxide. Precautions were taken to prevent Venous Air Embolism (VAE), which included the use of a precordial Doppler and adequate head elevation of the patient. Anaesthesia was maintained with a fentanyl-sevoflurane-air-oxygen regimen. Extubation was complicated by transient laryngospasm, requiring reintubation. Postoperative care was notable for the presence of transient pneumocephalus, which resolved with supportive care. The patient was successfully extubated on postoperative day 3, showed complete neurological recovery, and was discharged on day 7. This unique case highlights the challenges faced in managing posterior fossa tumours such as perimesencephalic epidermoid cysts, which require multidisciplinary anaesthetic approaches and vigilant postoperative care to ensure adequate neurological outcomes.