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Developmental anomalies affecting the hind brain, cerebellum and spinal cord with associated malformations of the skull base and cervical spine, show a wide degree of variability and overlap so that cases are often difficult to classify into a fixed category such as the Arnold-Chiari malformation Type 1 or Type 2, or the Dandy-Walker syndrome. The 4 cases presented here illustrate this problem and offer support for the hypothesis that these conditions may be merely the varying expression of a common pathological process. The CT brain scan may prove to be a valuable means of allowing early recognition of these anomalies so that effective surgical treatment can be given at an early stage in their natural history, possibly thereby preventing the progression or development of central cord cavitation with its significant and permanent disabilities.

The close association of the external and internal carotid circulations in the orbital cavity is well recognized. Two cases are presented in which local trauma to the orbit apparently resulted in the formation of an arteriovenous fistula. These lesions progressively expanded, producing classical features of proptosis, chemosis, and bruit. The investigation by selective angiograms and the surgical management of these malformations are discussed. A further case is presented in which an early lesion was noted in angiography after a head injury, with subsequent disappearance of the lesion some weeks later.

The causes of visual loss in benign intracranial hypertension are related to long standing papilloedema, ischaemic optic neuropathy or haemorrhage into a subretinal neovascular membrane. Decompression procedures generally preserve or improve visual acuity but surgical treatment with subtemporal decompression may lead to visual impairment. Such a deficit has been recorded in the past as occurring with ventriculography. Postulated mechanisms have included brain herniation, spasm of vessels supplying the visual cortices or retinal vascular disturbance. To our knowledge treatment with lumboperitoneal shunting has not previously been reported as leading to further significant visual loss in this condition. This report describes such an occurrence in a patient. Retinal vascular disturbance is postulated on the basis of several normal CT scans, normal CSF pressure measured after surgery and visual evoked responses suggesting retinal or optic nerve damage.

The close association of the external and internal carotid circulations in the orbital cavity is well recognized. Two cases are presented in which local trauma to the orbit apparently resulted in the formation of an arteriovenous fistula. These lesions progressively expanded, producing classical features of proptosis, chemosis, and bruit. The investigation by selective angiograms and the surgical management of these malformations are discussed. A further case is presented in which an early lesion was noted in angiography after a head injury, with subsequent disappearance of the lesion some weeks later.