Radiological and clinical features of an arachnoid cyst of the quadrigeminal cistern.

Cummins, Taveras, and Schlesinger (1960) have emphasized again the high mortality rate associated with surgical exploration of lesions in the region of the posterior third ventricle. However, there are certain benign processes which occur in this area which require definitive surgical treatment rather than shunting procedures and/or radiation therapy, and the successful management of obstructing mass lesions in this critical area is dependent upon correct pre-operative diagnosis. This report records an example of an arachnoid cyst of the quadrigeminal cistern. Nine similar cases have been recorded previously. Hamby and Gardner (1935) described a 16-year-old girl who complained of deafness and suffered from increased intracranial pressure resulting from an ependymal cyst in the supracollicular area. Their patient recovered after surgical evacuation of the cyst through the anterior medullary velum. Although the cyst wall was composed of ependymal cells there was neither radiological nor surgical evidence of a communication between the cyst and the ventricular system. Alexander (1953) reported an 18month-old patient with an arachnoid cyst of the quadrigeminal cistern. Severe obstructive hydrocephalus was relieved by the operative establishment of a communication between the posterior end of the third ventricle and the cyst. This child, when evaluated three years post-operatively, showed residual spasticity and moderate retardation on psychological testing. Dott and Gillingham (1958) described an infant suffering from spasticity and an enlarging head. A large arachnoid cyst of the supracollicular region was drained through the right ventricle, but the patient died of a postoperative haematoma. Katagiri (1960) recorded two cases of arachnoid cyst of the cisterna ambiens, but the illustrations indicated that these lesions were in fact in the quadrigeminal cistern. Both patients were adults. One died after surgery; the other was 'cured' by ventricular taps. Noetzel (1940) reported three patients with cysts in the cisterna ambiens in whom the symptoms resembled the clinical picture of pineal tumour. Hoshino, quoted by Katagiri (1960), recorded one case in which a cyst in this area produced ventriculographic findings suggestive of a tumour of the quadrigeminal plate. Dyke (1959), in 'Diagnostic Roentgenology', illustrated a lateral film from a ventriculogram which was labelled a 'cyst of dura'. His case, in our opinion, would seem to represent an arachnoid or ependymal cyst of the quadrigeminal cistern.