Vestibulocervical reflexes in idiopathic Parkinson disease

The mechanism of gait instability in Parkinson disease (PD) is not completely understood. We examined the saccular part of the otolith function and its possible contribution to gait difficulties in idiopathic PD.

Fifty-four PD patients (mean age 66 years, 32 men) were included. These were characterized with respect to disease severity, duration, treatment, as well as the presence of disease complications, dementia and depression. Vestibular evoked myogenic potentials (VEMP) were recorded in patients and 53 healthy controls.

VEMP responses were recorded in all controls. Unilaterally absent VEMP responses were found in 20 (37%) of PD patients and bilaterally absent responses in four (7.4%). All patients with preserved peaks had normal latencies as compared with controls. The number of PD patients with abnormal/absent VEMP was thus significantly higher than in controls (p<0.00). There were no correlations between VEMP abnormality and disease stage, falls or medication. A correlation was found between abnormal VEMP and depression/antidepressant treatment.

PD patients often have absent vestibulocollic reflexes. Further investigations are needed to elucidate the significance of this finding for postural stability and gait in this disorder.