Ocular counterrolling abnormalities in spasmodic torticollis
S. G. Diamond, C. H. Markham and R. W. Baloh
Department of Neurology, UCLA School of Medicine 90024-1769.
Spasmodic torticollis is a focal dystonic movement disorder of unknown
origin, long hypothesized to have some vestibular involvement. An
examination of otolith function, ocular counterrolling, was performed on
eight patients with this disorder. The test consisted of photographing both
eyes while the subject underwent rotation in both naso-occipital and
earth-horizontal long axes. Measurements of eye torsion were made with a
superimposition technique accurate to 0.1 degrees. Results showed all eight
patients had abnormal ocular counterrolling. The most notable defect was
the lack of sustained eye torsion at the extreme positions, resulting in
rolling of the eyes in the direction of head tilt rather than
counterrolling, a phenomenon previously observed only in persons with known
brain-stem problems. That finding, as well as the majority of the patients
showing spontaneous vestibular nystagmus in the dark and directional
preponderance with caloric stimulation, implies that one difficulty in
spasmodic torticollis lies in central vestibular connections, manifested by
disruption of brain-stem pathways.
