Cervical dystonia: a neural integrator disorder.
Ocular motor neural integrators ensure that eyes are held steady in straight-ahead and eccentric positions of gaze. Abnormal function of the ocular motor neural integrator leads to centripetal drifts of the eyes with consequent gaze-evoked nystagmus. In 2002 a neural integrator, analogous to that in the ocular motor system, was proposed for the control of head movements. Recently, a counterpart of gaze-evoked eye nystagmus was identified for head movements; in which the head could not be held steady in eccentric positions on the trunk. These findings lead to a novel pathophysiological explanation in cervical dystonia, which proposed that the abnormalities of head movements stem from a malfunctioning head neural integrator, either intrinsically or as a result of impaired cerebellar, basal ganglia, or peripheral feedback. Here we briefly recapitulate the history of the neural integrator for eye movements, then further develop the idea of a neural integrator for head movements, and finally discuss its putative role in cervical dystonia. We hypothesize that changing the activity in an impaired head neural integrator, by modulating feedback, could treat dystonia.
1 Department of Neurology, Case Western Reserve University, Cleveland, OH, USA 2 Daroff-DelOsso Ocular Motility Laboratory, Neurology Service, Louis Stoke VA Medical Center, Cleveland, OH, USA aasefshaikh@gmail.com.
Aasef G
AG
Shaikh
3 Department of Neurology, The Johns Hopkins University, Baltimore, MD, USA.
David S
DS
Zee
4 Centre for Vision Research and Departments of Psychology, Biology, and Kinesiology and Health Sciences, York University, Toronto, ON, Canada.
J Douglas
JD
Crawford
5 Department of Neurology, Emory University, Atlanta, GA, USA.
Hyder A
HA
Jinnah
D005133:Eye Movements / Q000502:physiology; D019416:Head Movements / Q000502:physiology; D006801:Humans; D009422:Nervous System Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D009759:Nystagmus, Pathologic / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D014103:Torticollis / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology
cerebellum; integrator; midbrain; nystagmus; tremor