COLLOID CYST OF THE 3RD VENTRICLE AS A CAUSE OF ACUTE NEUROLOGICAL DETERIORATION AND SUDDEN-DEATH

A 13 year old girl presented with a 24 h history of headache and vomit ing. There were no focal neurological signs. The diagnoses considered were vascular headache, meningitis and subarachnoid haemorrhage. Lumba r puncture revealed clear cerebrospinal fluid under high pressure and subsequent cerebral computed tomography (CT) scan revealed hydrocephal us. Death occurred some hours after the lumbar puncture. Autopsy revea led a colloid cyst of the 3rd ventricle causing the hydrocephalus. Cer ebellar tonsillar herniation was present. This case is reported becaus e although 3rd ventricular colloid cysts are a recognized cause of acu te neurological deterioration and sudden death, they rarely present in childhood. In this case, it is considered that lumbar puncture may ha ve hastened death by increasing brain-stem compression due to cerebell ar tonsillar herniation. It raises the question of whether cerebral CT scan, where readily available, should be performed prior to lumbar pu ncture. Pathologically, colloid cysts may be easily missed if the brai n is examined fresh as the cysts are fragile and have a tendency to be destroyed or fall out.