Lumboperitoneal shunt surgery for idiopathic normal pressure hydrocephalus (SINPHONI-2): an open-label randomised trial.

BACKGROUND: Lumboperitoneal shunt surgery has the potential to alleviate symptoms of normal pressure hydrocephalus but the benefits of such surgery have not been tested in a randomised trial. The aim of this trial was to determine the safety and efficacy of the lumboperitoneal shunt surgery for this disorder.

METHODS: For the open-label randomised SINPHONI-2 trial, eligible participants (60-85 years of age) with idiopathic normal pressure hydrocephalus, with ventriculomegaly, and tightness of the high-convexity and medial subarachnoid spaces on MRI, were recruited from 20 neurological and neurosurgical centres in Japan. Enrolled participants were randomly assigned in a 1:1 ratio according to a random code generated by the trial statistician, with a permuted block design (using a block size of 4 or 6) within each centre, to receive lumboperitoneal shunt surgery within 1 month after randomisation, or to surgery postponed for 3 months. Patients and assessors were not masked to treatment assignment. The primary endpoint was favourable outcome, defined as an improvement of one point or more on the modified Rankin scale (mRS) at 3 months after randomisation, analysed by intention to treat, and the main secondary endpoint was the same outcome 12 months after surgery, analysed per protocol. This trial is registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR), number UMIN000002730.

FINDINGS: Between March 1, 2010, and Oct 19, 2011, 93 patients with idiopathic normal pressure hydrocephalus were enrolled and randomly assigned to the immediate treatment group (n=49) or the postponed treatment group (n=44). More patients in the immediate treatment group than in the postponed treatment group had an improvement of one point or more on the mRS at 3 months: 32 (65%) of 49 in the immediate group vs 2 (5%) of 44 in the postponed group (difference 61% [95% CI 42-68]; p<0·0001). The number of patients who had an improvement of one point or more on the mRS at 12 months after surgery was similar between the two groups: 30 (67%) of 45 patients in the immediate group vs 22 (58%) of 38 in the postponed group (difference 9% [95% CI -14 to 31]; p=0·496). The proportions of patients with serious adverse events did not differ significantly between the groups during the 3 months post-randomisation (7 [15%] of 46 in the immediate group vs 1 [2%] of 42 in the postponed group; p=0·060). During the 12 months after surgery, 19 (22%) of 87 patients had serious adverse events, the most common of which was cerebral infarction (six patients [7%]).

INTERPRETATION: Our results suggest that lumboperitoneal shunt surgery might be beneficial for patients with idiopathic normal pressure hydrocephalus and, if these findings are confirmed in larger studies, could be a first-line treatment option for this disease.

FUNDING: Johnson & Johnson and Nihon Medi-Physics.