Results of Isotope Cisternography in 175 Patients with a Suspected Hydrocephalus

Normal pressure hydrocephalus (NPH) is a syndrome characterized by gait disturbance, memory impairment and urinary incontinence. The isotope cisternography (ICG) became less useful because of low accuracy and complications. We tried to evaluate the safety and value of the ICG.

We retrospectively collected data on ICG of 175 consecutive patients with a suspected hydrocephalus. We classified the ICG into four types by the ventricular reflux and circulation time. The ventricular size was measured by Evans index and the width of the third ventricle.

There were three complications including one case of paraplegia. Type 4 was the most common type, observed in 53%. Type 3 (33%), type 2 (7%), and type 1 (7%) were observed less often. Type 4 was more common in patients with large ventricles. Types of the ICG were not related to the causes of hydrocephalus, gender, or age of the patients. Shunting was more frequently performed in type 4 (71%), compared to type 1 (17%), type 2 (33%), and type 3 (46%). Surgery was more common when the cause was vascular. After the shunt surgery, 33.0% were graded as the improved. Although there were some improvements even in the not-improved patients, they still needed many helps. The improvement was related to the preoperative state.

ICG may bring a serious complication, however the incidence is very low. Although the predictability of response rate on the shunting is doubtful, ICG is a cheap and useful tool to select surgical candidates in NPH.