Value of continuous spinal drainage in normal pressure hydrocephalus and secondary communicating hydrocephalus

Abstract

Out of 30 cases of suspected normal pressure hydrocephalus (NPH) and/or secondary communicating hydrocephalus which showed mental disturbance and ventricular dilatation on CT scan and/or by pneumoencephalography, 18 showed a lumbar CSF pressure within normal limits, seven over 200 mmH2O, and five under 100 mm H2O. On 16 cases, continuous spinal drainage (CSD) was performed. The CSD procedure consisted of placing an epidural anesthesia catheter into the lumbar subarachnoid space for about 7 days. The amount of drained CSF was limited to 150-200 ml/day and was adjusted according to the clinical symptoms. If a certain improvement in the clinical symptoms was noted, the patient was diagnosed as a treatable communicating hydrocephalus and was then submitted to a shunting operation. The authors achieved 100% success in the shunting operations of the 13 cases, which fulfilled the above diagnostic criteria. The other three cases, without the effective CSD, did not show any satisfactory results from the shunting operation. CSF drainage test has reportedly been performed to diagnose the reversible brain changes and indications for the shunting operation. This test appears to have the same meaning as the CSD in the early stage of NPH or in the high pressure hydrocephalus, and is also less cumbersome to patients than the CSD. But, in the late stage of NPH and in the low pressure hydrocephalus, this test is apparently unable to predict the effectiveness. The CSD should be performed in cases with an ineffective CSF drainage test. In secondary hydrocephalus, especially in NPH, the most important factor in the success of the shunting operation, should be that there are still reversible changes in the brain tissue on the circumference of the ventricles. Therefore, NPH should mean the condition of the brain and not the name of a disease. The authors would like to name the treatable secondary hydrocephalus as the “Adams-Hakim's syndrome”, and to classify it into the low pressure type, normal pressure type, and high pressure type.