Objective: Objective of the work was to study the prevalence of sleep disorders, Rem Sleep Behaviour Disorder (RBD) and obstructive sleep apnea (OSA) in patients with NPH.

Background: Normotensive hydrocephalus (NPH) is a neurological condition typical of the elderly due to ventricular system enlargement. It is clinically characterized by locomotor, cognitive, and urinary disturbances. Patients with NPH can broadly present with two different phenotypes; the first one mainly characterized by gait unsteadiness (i.e., imbalance subtype) and the second one by parkinsonism (i.e., locomotor subtype). The latter has been associated with greater loss of dopaminergic “binding” in the striatum, especially in the caudate nucleus, which is only partially reversible after shunt, but its conversion into a neurodegeneration process is matter of debate. RBD, a prodromal marker of synucleinopathies, could predict such conversion. Moreover, regular sleep plays a key role in the homeostatic lymphatic regulation, while OSA has been suggested to be a risk factor for NPH. Indeed, OSA’s prevalence is high in NPH (ranging from 65 to 90%), and OSA may alter the CSF homeostasis by mediating a mechanical alteration in the cerebral vascular dynamics.

Method: We administered specific sleep questionnaires such as Hong Kong Scale (HKS) for RBD, Berlin Questionnaire (BQ) for OSA, and Epworth Sleepiness Scale (ESS) and Pittsburgh Sleep Quality Index (PSQI) for the sleep quality assessment in a cohort of 87 unselected patients (54 males, 34 females; mean age 72,3 years) and we performed a videopolysomnography study.

Results: A minority of patients (22/89; 24,7%) suffered from RBD (HKS score ≥ 18; mean: 30,9, sd:14,9). The risk for OSA was high in 32.6% (28/89, BQ total score 2) and low in 26.9% (BQ-total score1). Almost half of our cases (48%) had significant day time sleepiness, as evaluated by EES (mean 9,13, ds 5.8) and the majority of them (73%) had poor quality of sleep, as shown by PSQI (significative ≥ 5, mean 8.7). 31 patients underwent a video-polysomnography study which revealed a significative Apnea/Ipopnea Index (AHI > 20) in 14 of them (45%). None of the NPH patients manifested RBD full blown or present REM without atonia (RWA)

Conclusion: Clinical interviews and polysomnography study demonstrated that OSA has significative prevalent in the NPH patients. Conversely there is no instrumental evidence of RBD in this subset of  NPH patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/sleep-disorders-in-normotensive-hydrocephalus/