Lumbosubarachnoid-lumboepidural shunting in patients with idiopathic normal-pressure hydrocephalus: surgical procedures and follow-up study of five cases.

The objective of the study is to introduce the surgical procedure of the lumbosubarachnoid-lumboepidural (L-L) shunting performed as treatment for idiopathic normal-pressure hydrocephalus (iNPH) and its follow-up. The subjects were five patients with probable iNPH (aged 78-85 years; mean age 81 years; four males and one female) who were judged to be at high risk from general or lumbar anesthesia due to their systemic complications and age. The L-L shunt operation was performed for all the patients under local anesthesia using Codman-Hakim Programmable Valve(®) (Codman & Shurtleff, Inc., Raynham, Massachusetts, USA). The initial pressure for all patients was set at 8 cmH2O. The evaluation of shunt efficacy and the lumbar epidural space cerebrospinal fluid (CSF) absorption test (injection of contrast media into epidural space) were performed both on the operation day and during follow-up period (9-12 months). The shunt operation was judged to be effective in four out of five patients (regarded as shunt responders), whereas no improvement in symptoms was seen in one patient (regarded as shunt nonresponder) where the shunting had no effect after the initial pressure was changed to 4 cmH2O. The lumbar epidural space CSF absorption test both on the operation day and during the follow-up period confirmed absorption in all patients. The L-L shunting is useful for patients with probable iNPH who are at high risk from general or lumbar anesthesia due to their systemic complications and age. CSF was continuously absorbed in the lumbar epidural space during postoperative follow-up period. A longer follow-up is required to establish this surgical procedure.