Sudden death due to 4th ventricle arachnoid cyst

Abstract

Arachnoid cysts are benign developmental anomalies located in the arachnoid matter. Occurrence in the fourth ventricle is rare with only 11 cases reported in the literature [1]. We describe our experience with such a case. A 39-year old woman residing in a remote island presented to a hospital with a few weeks history of worsening morning headaches and vomiting. Neurological examination was unremarkable except for bilateral papilloedema on fundoscopy. Subsequent CT and MR imaging revealed an arachnoid cyst within the fourth ventricle, accompanied by marked enlargement of the ventricular system. The patient underwent a midline, suboccipital craniotomy, cyst evacuation and partial membrane excision. Histology confirmed the initial diagnosis. As symptoms persisted, she was offered a ventriculoperitoneal shunt (VP) insertion, which led to complete symptom remission. She was discharged home after an uneventful postoperative period. One year later, she complained of a sudden worsening headache, blurred vision and started vomiting. On initial assessment at her local hospital, her Glasgow Comma Scale (GCS) was 13. Symptoms were attributed to shunt malfunction and arrangements were made for immediate helicopter transfer to our department. Meanwhile, the patient gradually deteriorated to a GCS of 8 and was intubated. By the time she reached our unit, 4-h post intubation, her GCS was 3 and her pupils had been fixed and dilated for 3 h. Brain computed tomography depicted re-accumulation of the cyst within the compartment of the fourth ventricle exerting significant compression, causing brainstem distortion (Fig. 1). The patient was not under sedation and examination of brainstem reflexes revealed no activity No surgical treatment was offered and the patient passed away a few hours later. Autopsy confirmed the CT findings. Definitive management of arachnoid cysts is challenging as the recurrence rate is between 31 and 60% [2, 3]. In the few reported cases, some authors proceeded to partial or complete cyst excision which both appeared to provide adequate symptom alleviation. Some others offered