Background: The proposed mechanisms for the sensory trick include peripheral sensory feedback to aid in correcting abnormal posture or movement.
Case report: A 53-year-old woman with cervical dystonia underwent magnetoencephalography pre- and post-botulinum toxin injection and sensory trick, which was described as yawning. Study revealed connectivity between the left frontal and inferior frontal gyrus before yawning, which changed to the visual cortex and right middle frontal gyrus with yawning. Beta frequencies reduced and gamma frequencies increased after yawning.
Discussion: The increase in gamma frequency bands may indicate increased GABAergic activity. Increase in connectivity in the right cerebellar region underscores the importance of cerebellum in pathogenesis of dystonia.
Keywords: botulinum toxin; cervical dystonia; functional imaging; magnetoencephalography; sensory trick.