The blink reflex in patients with idiopathic torsion dystonia
K. Nakashima, J. C. Rothwell, P. D. Thompson, B. L. Day, A. Berardelli, R. Agostino, J. Artieda, S. M. Papas, J. A. Obeso and C. D. Marsden
Medical Research Council Human Movement and Balance Unit, Institute of Neurology, London, England.
The blink reflex and its recovery cycle were examined in 57 patients with
idiopathic dystonia affecting different parts of the body. The group
comprised 9 patients with generalized and 15 with segmental forms, 19 with
torticollis, and 14 with focal arm dystonia. None had blepharospasm. The
duration and amplitude of the R2 component of the blink reflex showed only
minor changes. However, its recovery cycle to paired supraorbital nerve
stimuli was abnormal in all groups of patients, except those with focal arm
dystonia. These findings may be interpreted as showing abnormal control of
the interneuronal networks mediating the blink reflex in patients with
dystonia affecting sites other than the facial muscles. The fact that the
principal changes were seen in patients with torticollis, and generalized
or segmental dystonia, suggests that the extent of dystonia (rather than
the severity) and, therefore, the close proximity to the cranial muscles
was important in determining the extent of the abnormal interneuron
function.
