Why do patients with PSP fall? Evidence for abnormal otolith responses.
BACKGROUND
Patients with progressive supranuclear palsy (PSP) fall frequently, beginning early in the course of their disease. Abnormal vestibulospinal reflexes are suspected, but the angular vestibulo-ocular reflex, which is mediated by the labyrinthine semicircular canals, survives late into the course of the disease.


OBJECTIVE
To test the hypothesis that otolithic-mediated reflexes are abnormal in PSP.


METHODS
We tested otolith-ocular reflexes (the translational vestibulo-ocular reflex [tVOR]) during combined rotation-translation in nine patients with PSP and nine age-matched control subjects; subjects viewed far and near targets. We also tested click-induced otolith-spinal reflexes (vestibular-evoked myogenic potentials [VEMPs]) in 10 patients with PSP and 30 age-matched controls.


RESULTS
All patients with PSP had small tVOR responses during near viewing that were, on average, only 12% of those of control subjects (p = 0.001). Patients with PSP also showed a reduction of the amplitude of VEMPs compared to control subjects (median [range]: 54.3 [16.8 to 214] vs 149 [11.6 to 466], p = 0.001).


CONCLUSIONS
Taken together, these results indicate that abnormal otolith-mediated reflexes may be at least partly responsible for frequent falls in progressive supranuclear palsy, and deserve further study.
Liao
K
K
Neurology Service and Daroff-Dell'Osso Laboratory, Veterans Affairs Medical Center and University Hospitals, Case Western Reserve University, Cleveland, OH, USA.
Wagner
J
J
Joshi
A
A
Estrovich
I
I
Walker
M F
MF
Strupp
M
M
Leigh
R J
RJ
D000058:Accidental Falls; D000368:Aged; D004525:Efferent Pathways / Q000503:physiopathology; D005260:Female; D019416:Head Movements / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000294:innervation / Q000503:physiopathology; D010037:Otolithic Membrane / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology; D012021:Reflex, Abnormal / Q000502:physiology; D012027:Reflex, Vestibulo-Ocular / Q000502:physiology; D012444:Saccule and Utricle / Q000503:physiopathology; D054776:Semicircular Ducts / Q000503:physiopathology; D013494:Supranuclear Palsy, Progressive / Q000150:complications* / Q000503:physiopathology*; D015837:Vestibular Diseases / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D014724:Vestibular Function Tests; D014726:Vestibular Nuclei / Q000503:physiopathology; D014722:Vestibule, Labyrinth / Q000503:physiopathology*