Neurovestibular analysis and falls in Parkinson's disease and atypical parkinsonism.

The primary aim of our study was to determine the extent of vestibular dysfunction in patients with Parkinson's disease (PD). Our secondary aim was to determine if vestibular dysfunction in PD is a risk factor for falling. The tertiary aim was to determine both the extent of vestibular dysfunction and if this dysfunction is a risk factor for falling in patients with atypical parkinsonism (AP). Twenty-five healthy subjects, 30 PD patients and 14 AP patients were matched for age and gender in a case-control study design. All subjects underwent clinical neurological and neurotological assessments, cervical and ocular vestibular evoked myogenic potentials (VEMPs), brainstem auditory evoked potentials (BAEPs), subjective visual vertical measurements, and videonystagmography with caloric and rotatory chair stimulation. Ninety per cent of PD patients (27 of 30) and all 14 AP patients had signs of vestibular dysfunction on laboratory examinations. The evoked potential (VEMPs and BAEPs) test results of PD patients showed significant prolongation of the p13, n1 and interpeak III-V latencies on the symptomatic brainstem side (0.003 ≤  P ≤ 0.019) compared with healthy subjects. Also, vestibular testing abnormalities were correlated with an increased risk for falling when fallers among PD and AP patients were compared with the non-fallers (P ≤ 0.001). To conclude, vestibular dysfunction on vestibular laboratory testing is highly prevalent in both PD and AP patients compared with healthy subjects, and is associated with an increased risk for falling.