Use of external lumbar cerebrospinal fluid drainage and lumboperitoneal shunts with Strata NSC valves in idiopathic normal pressure hydrocephalus: a single-center experience

Objective: In Japan, idiopathic normal pressure hydrocephalus (iNPH) currently is treated mainly with lumboperitoneal (LP) shunts. Our aim was to evaluate whether LP shunting via the use of Medtronic Strata NSC programmable valves was as effective as ventriculoperitoneal shunting in the treatment of patients with iNPH from the perspectives of safety and symptomatic improvement rate.

Methods: The clinical records of 51 iNPH patients (mean age, 75 years; males, 29), who underwent placement of Medtronic Strata NSC LP shunt systems were reviewed retrospectively as a cohort. LP shunting was evaluated with the modified Rankin Scale, the Japan Normal-Pressure Hydrocephalus Grading Scale, the Mini-Mental State Examination, the Frontal Assessment Battery, and the Trail-Making Test A as outcome measures.

Results: Modified Rankin Scale scores improved from 3.2 to 2.2 (P < 0.01), indicating a 64% response rate 12 months after treatment. Total Japan Normal-Pressure Hydrocephalus Grading Scale scores decreased from 6.5 to 4.0 (P < 0.01), indicating a response rate of 81%. Mini-Mental State Examination scores improved from 22.2 to 25.4 (P < 0.01), Frontal Assessment Battery scores improved from 11.7 to 13.4 (P < 0.05), and Trail-Making Test A scores improved from 122.3 to 112.7 (P = 0.60). During the 12-month follow-up period, complications requiring surgery were observed in 6 cases (11.8%).

Conclusion: LP shunts showed effectiveness rates that were similar to those of ventriculoperitoneal shunts. Despite the relatively high complication rate, LP shunts can be recommended for the treatment of patients with iNPH because of their minimal invasiveness and lack of lethal complications.