Radioiodinated serum albumin (RISA) cisternography in the diagnosis of incisural block and occult hydrocephalus

Fistula detection in cerebrospinal fluid leakage

In two cases of cerebrospinal fluid rhinorrhoea in which scinticisternography failed to identify the fistulae, the tracts were demonstrated by positive contrast ventriculography. It is postulated that the fistula communicated with the ventricles but was isolated from the subarachnoid space by adhesions (demonstrated at operation in one case). There was `high pressure rhinorrhoea' in one case. The rhinorrhoea ceased after insertion of ventriculoatrial shunt.

Progressive ventricular dilatation following pneumonencephalography. A radiological sign of occult hydrocephalus

✓ Eight patients with “normal pressure hydrocephalus” are presented who demonstrated radiographic and occasional clinical evidence of progressive dilatation of the ventricles following pneumoencephalography. The characteristic pneumographic signs of tentorial obstruction to the flow of cerebrospinal fluid (CSF) had been documented in the original air contrast study. The authors postulate that pneumoencephalography in patients with normal pressure hydrocephalus may result in a sudden displacement of CSF from the ventricles into the already compromised basal cisterns, leading to further obstruction of CSF outflow and progressive ventricular dilatation. Other mechanisms such as reduction in the potential resorptive capacity of the ventricular ependyma by air replacing ventricular fluid may play a part. The value of repeat radiological studies 24 and 48 hours after the original pneumogram is emphasized both as an aid in the radiological diagnosis of normal pressure hydrocephalus and as an additional parameter for studying problems in CSF flow and absorption.