Decreased dopamine D receptor binding in essential blepharospasm.

OBJECTIVES: The purpose of this study was to investigate whether dopamine D(2) receptor binding was altered in the striatum of essential blepharospasm patients.

METHODS: Striatal dopamine D(2) receptor binding was measured with positron emission tomography and [(11)C]raclopride. We studied eight drug-naive patients with bilateral blepharospasm and eight age-matched normal controls.

RESULTS: The uptake indices in the blepharospasm group were significantly reduced by 11.7% in the caudate (P < 0.005), 11.6% in the anterior putamen (P < 0.0001), and 10.3% in the posterior putamen (P < 0.005) relative to the control group.

CONCLUSIONS: This study indicates decreased dopamine D(2) receptor binding in the entire striatal region of blepharospasm patients. The findings suggest that decreased dopamine D(2) receptor binding might be one of the predisposing factors that leads to the dysfunction of the motor circuit, resulting in the loss of broad inhibition of unwanted movements during an intended movement in blepharospasm patients.