Mechanisms of vestibulo-ocular reflex (VOR) cancellation in spinocerebellar ataxia type 3 (SCA-3) and episodic ataxia type 2 (EA-2)

Progress in Brain Research
Carlos R GordonAri Z Zivotofsky

Abstract

The vestibulo-ocular reflex (VOR) mechanism triggers eye movements as a result of head motion in order to keep gaze stationary relative to the world. However, in order to shift the direction of the gaze along with head motion, the VOR mechanism must be overridden ("cancelled"). Two mechanisms have been proposed to explain this cancellation: a reduction of the VOR gain or activation of smooth pursuit (SP) eye movements in the opposite direction. We studied VOR cancellation using the magnetic search coil in six spinocerebellar ataxia type 3 (SCA-3) and four episodic ataxia type 2 (EA-2) patients, conditions that are known to have degraded SP but different degrees of VOR impairment. Abnormal VOR was found in two of the four EA-2 patients and all of the SCA-3 patients. All subjects possessed residual VOR, although when tested using head thrusts it was almost negligible in the SCA-3 patients. The EA-2 patients showed essentially no SP and the SCA-3 patients had poor SP. However, for all patients, the gain during VOR cancellation was comparable to normals. These results provide additional evidence that SP cancellation of the VOR cannot be the sole mechanism utilized in overriding the VOR in these patients.

Citations

Nov 26, 2010·Current Opinion in Neurology·Caroline Tilikete, Alain Vighetto
Jul 10, 2016·Journal of Vestibular Research : Equilibrium & Orientation·L LuisJ Valls-Solé
Mar 30, 2021·Journal of the Neurological Sciences·Dario GeisingerCarlos R Gordon
Oct 29, 2021·Journal of Neurology·Jae-Hwan ChoiKwang-Dong Choi
Jan 4, 2022·Physiotherapy Theory and Practice·Carrie A Barrett, Donald L Hoover

❮ Previous
Next ❯

Related Concepts

Related Feeds

Ataxias

Ataxia is a neurological condition characterized by lack of voluntary coordination of muscle movements including loss of coordination, balance, and speech. Discover the latest research on different types of ataxias here.

Ataxias (MDS)

Ataxia is a neurological condition characterized by lack of voluntary coordination of muscle movements including loss of coordination, balance, and speech. Discover the latest research on ataxia here.

Ataxia

Ataxia is a neurological condition characterized by lack of voluntary coordination of muscle movements including loss of coordination, balance, and speech. Discover the latest research on ataxia here.

Cajal Bodies & Gems

Cajal bodies or coiled bodies are dense foci of coilin protein. Gemini of Cajal bodies, or gems, are microscopically similar to Cajal bodies. It is believed that Cajal bodies play important roles in RNA processing while gems assist the Cajal bodies. Find the latest research on Cajal bodies and gems here.