Effects of Botulinum Toxin in Cervical Dystonia

Overview

Botulinum toxin injection in the contracting muscles has proven to be a safe and effective method of relieving pain and lessening dystonic posturing. The current hypothesis is that botulinum toxin works on altering sensory input in the central nervous system in addition to its effects on the neuromuscular junction. Magnetoencephalography (MEG)of brain has been used in dystonia such as writer's cramp and musician's hand dystonia. However, no study has investigated the correlation of central signal changes via magnetoencephalography before and after treatment with botulinum in torticollis patients. Prior studies using somatosensory potentials indicated the possibility of differential activation of precentral cortex in patients with cervical dystonia. Cervical dystonia may result from a disorder of both cortical excitability and intracortical inhibition. The investigators hypothesis is that botulinum injection modulates central inhibition which improves clinical outcome for torticollis.

This study of MEG neuro-imagery will increase the understanding of the central pathway involvement in the efficacy of botulinum toxin treatment for torticollis. Cervical dystonia (spasmodic torticollis) patients will be selected from the Neurology clinic. Subjects will range in age from 18 years old through 90 years old. Subjects are expected to be ambulatory and independent. Patients are generally expected to be in good health. Exclusion criteria include significant intracranial metal (typically fixed dental bridges or braces) generating significant magnetic artifact, medical instability, pregnancy, and certain other factors such as severe head tremors that would produce magnetic artifact. Clinical states of torticollis patients will be assessed by using Tsui scale. Every torticollis patient will have magnetoencephalography on the day of botulinum treatment beforehand and approximately 2-8 weeks after botulinum treatment. We will compare the results of magnetoencephalography between control subject and torticollis patient before botulinum treatment aiming to find any difference between the two populations. We also compare the results of magnetoencephalography in individual torticollis patient before and after botulinum treatment, aiming to detect the changes between these two conditions in the same individual and possibly between the average of data from each condition before and after botulinum treatment.