Diminished regional cerebral blood flow response to vibration in patients with blepharospasm

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Abstract
Objective: To determine whether patients with blepharospasm have abnormal sensorimotor processing similar to patients with writer’s cramp. Background: Blepharospasm is a focal dystonia manifest by involuntary, excessive blinking and squeezing of the eyes. Altered sensorimotor processing may contribute to the development of dystonic movements. Previously the authors demonstrated decreased vibration-induced cortical blood flow responses in hand primary sensorimotor area (PSA) in patients with hand dystonia. Methods: In this prospective, case–control study, seven patients with blepharospasm were compared with seven normal subjects. PET measurements of regional blood flow were obtained using bolus administration of H215O at rest or during sequential vibration of either the left or the right hand or side of the mouth. Results: PSA activation decreased significantly in the patients with blepharospasm both ipsilateral (−68%; p= 0.0004) and contralateral to the side of facial stimulation (−56%; p = 0.0009). Patients had a 31% lower mean contralateral PSA response to hand vibration and a 51% smaller right supplementary motor area response to left-hand vibration than normal subjects, but these differences did not reach statistical significance. Conclusions: Patients with blepharospasm have abnormal sensorimotor processing in response to lower face vibration. They may also have abnormal brain responses to stimulation of clinically uninvolved parts of the body, but this requires confirmation.