Oligodendrogliomas comprise approximately 4% of the total of brain tumours, and of this group only 7% are found in the posterior fossa, including 2% in the fourth ventricle. Oligodendrogliomas of the fourth ventricle therefore comprise less than one case in 1,000 to 1,500 brain tumours (0 08 %). One cannot expect to encounter much more than one in a lifetime even in a large-neurosurgical experi...

Arachnoiditis in the posterior fossa is not a rare disorder in China. Eighty-two cases seen in a three year period were studied with reference to symptomatology, aetiology and treatment. The presentation was contrasted with that of increased intracranial pressure caused by tumour. The efficacy of treatment by direct exploration and shunt surgery was emphasised.

Reprint requests to Dr. F.W. Saunders, Division of Neurological Surgery. Kingston General Hospital, Kingston, Ontario, Canada, K7L 2V7. INTRODUCTION This report describes a 24 year old man with a posterior fossa medulloblastoma. His postoperative course was instructive because of the discrepancies that developed between the CT scan interpretations and the operative findings. His case history wi...

Tension pneumocephalus has been reported most frequently after posterior fossa surgery performed in the sitting position. We present a paediatric patient who developed tension pneumocephalus in the postoperative period after decompression of a craniopharyngioma performed with the patient in the supine position.

A retrospective study has been carried out on 67 patients with posterior fossa haemangioblastomata. Clinical details are presented, and the problems of diagnosis discussed. A fresh definition of the von Hippel-Lindau complex is put forward. The results of surgery are good for patients with solitary and sporadic tumours.

Arachnoid cysts are the most common congenital cystic lesions in the brain occurring in the middle fossa, suprasellar region and occasionally in the posterior fossa. Conventionally all cysts are considered as benign and symptoms are attributed to expansion of cysts causing compression of adjacent neurological structures, bleeds within the cyst or due to the development of acute hydrocephalus. W...

Variations of the posterior fossa blood supply are relatively uncommon but should be borne in mind by the clinician. We present two unusual cases of posterior cranial fossa blood supply and review the literature regarding such abnormalities. Both cases demonstrated a lack of the vertebrobasilar system to varying degrees. Such arterial variations as present herein should be known to the clinicia...

Neurenteric cysts (NC) are rare, endodermal-derived intracranial lesions, commonly located anteriorly in the posterior cranial fossa. We describe a rare case of a giant posterior fossa NC (6.5 × 5.9 × 4.3cm) located dorsal to the brain stem in a Chinese woman with a 1 week history of cerebellar symptoms. To our knowledge, this is the largest documented cyst of this type and the third dorsally l...