How should one investigate the posterior fossa?

The case notes of 170 consecutive patients with a suggestive clinical history, or a proven final diagnosis of a posterior fossa lesion have been analyzed in order to determine the precise value of each radiological investigation. All had had CT scans. The patients have been grouped clinically according to their presenting signs and symptoms. The analysis suggests some well-defined regimes of investigation and indicates the successes and failures of radiology.