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.