Clinical profile of idiopathic normal pressure hydrocephalus with reduced myocardial sympathetic nerve function

Findings of reduced cardiac sympathetic nerve function and pareidolic illusions have been useful for identifying Lewy body disease (LBD). Therefore, we aimed to investigate whether these findings are associated with a high prevalence of LBD-related symptoms and poor shunt responsiveness in patients with idiopathic normal pressure hydrocephalus (iNPH).

We retrospectively analyzed 104 iNPH patients who underwent preoperative ¹²³I-metaiodobenzylguanidine myocardial scintigraphy and the Pareidolia test. We divided the patients into the abnormal cardiac scan (AC) group and the normal cardiac scan (NC) group. The severity of gait, cognitive, and urinary disturbances; the prevalence of parkinsonism; the prevalence of behavioral and neuropsychiatric symptoms; and performance on neuropsychological assessments were compared between the two groups. Moreover, we investigated the changes in these measures after shunt surgery in each group.

Fifty-six (53.8 %) patients were classified into the AC group. Compared with patients in the NC group, the patients in the AC group had more frequent rigidity, resting tremor, hallucinations, and REM sleep behavior disorder, and greater deficits in attention, working memory, and visuospatial cognition. After shunt surgery, gait and urinary functions significantly improved in both groups. However, unlike in the NC group, no significant improvement in cognitive function was observed in the AC group.

Our results suggest that reduced cardiac sympathetic function in iNPH patients is linked to increased LBD-related clinical features and attenuated cognitive improvement after shunt surgery.