Protocolizing the Work-up for Idiopathic Normal Pressure Hydrocephalus Improves Outcomes

Background: The work-up for idiopathic normal pressure hydrocephalus (INPH) can be difficult to coordinate and determining appropriate patients for ventriculoperitoneal shunting can be challenging, so we hypothesized that implementing a formalized protocol can improve patient selection for shunt. In conjunction with neurology and neurosurgery, we instituted a standardized means of assessing patients whose presentation is concerning for INPH and compared their work-up with similar patients seen without the protocol (i.e., “pre-protocol” or PP) regarding baseline characteristics, assessment, and outcomes.

Methods: Twenty-six PP patients were compared with 40 protocol patients on measures, including baseline deficits, work-up, neurosurgical evaluation, and response to shunt.

Results: Average age was similar between groups and percentage of patients who had a decline in gait, cognition, and/or incontinence was not statistically different (p>0.05). Significantly more protocol patients underwent high-volume lumbar puncture (HVLP; 97.5%; PP, 61.5%; p<0.001) and received formalized gait assessment with The Gait Scale (90%; PP, 0%, p<0.001) and standardized cognitive testing (95%; PP, 38.5%; p<0.001). Significantly more protocol patients had no improvement after HVLP (33.3%; PP 6.25%, p<0.045); subsequently, fewer got shunted (57.5%; PP, 84.6%; p<0.030). More protocol patients who were shunted reported gait improvement (100%; PP, 72.7%; p=0.009), though there was no difference in cognition (59.2%; PP, 82.6%, p=0.108) or incontinence (18.2%; PP, 39.1%, p=0.189).

Conclusions: Implementing an INPH protocol leads to standardized and more extensive assessment and better patient selection for and subsequent outcomes from shunting, specifically regarding gait.