Fourth International Symposium on Neuroacanthocytosis

Abstracts from the Fourth International Symposium on Neuroacanthocytosis

July 1-2, 2008
London and Oxford

Chairs: Prof. Kailash Bhatia, MD, FRCP, Institute of Neurology, University College London; Prof. Anthony P. Monaco, MD, PhD, Wellcome Trust Centre for Human Genetics, University of Oxford

Organizers: Antonio Velayos-Baeza, PhD; Susanne Schneider, MD; Glenn Irvine

2-3 Biofeedback in dystonic syndromes
M. W. M. Horstink
Dept. of Neurology, Radboud University Medical Centre, Nijmegen. The Netherlands

The brain projects motor output on a specific group of muscles required for performing a specific task. During movement sensory feed-back afferents from the muscles provide input for motor control. Abnormal movement-related sensory input or abnormal sensorimotor processing in the brain results in abnormal postures or movements. We show the clinical proof of the impact of abnormal sensory feedback on movement in a patient with pseudoathetosis-dystonia caused by sensory polyneuropathy. Causalgiform dystonia-like cramps present probably the most extreme example of such abnormal peripherally induced sensorimotor disorder. Dystonia may also be caused by abnormal sensorimotor integration, resulting in a mismatch between sensory input versus motor output. In a number of patients with sensorimotor movement disorders the abnormal sensorimotor drive can be restored, overruled or evaded by behavioral manipulations of the sensorimotor loop. We show examples of the effect of sensory tricks in torticollis and oromandibular dystonia, the effect of blockade of a trigger muscle in midbrain tremor, and the effect of evading the disordered sensorimotor loop in writers cramp. We have systematically treated patients with writers cramp with behavioral therapy. The patients are taught to recognize the relationship between the level of EMG activity as shown on a screen and the contraction of the muscle. Patients are trained to reduce the excessive EMG to the minimum possible level while they were writing. In a majority of patients this therapy results in long-lasting improvement of writing. In a pilot study we found that behavioral therapy restored pre-existing lowered levels of dopamine receptors, suggesting that dopaminergic abnormalities in the basal ganglia in these patients are probably a secondary adaptation rather than the cause of writers cramp. Most of these therapies can probably not be applied in patients with extensive brain pathology because they may require full co-operation of compensatory parts in the brain.