FAMILIAL PAINFUL RESTLESS LEGS SYNDROME CORRELATES WITH PAIN DEPENDENT VARIATION OF BLOOD-FLOW TO THE CAUDATE, THALAMUS, AND ANTERIOR CINGULATE GYRUS

To understand the relationship of caudate, thalamic, and anterior cing ulate perfusion to pain states, we investigated familial restless legs syndrome in a father and daughter during the state of pain induced by immobility using semiquantitative regional cerebral blood flow (rCBF) brain single photon emission computed tomography (SPECT). The father underwent 4 brain SPECT scans using the rCBF tracer Tc-99m-HMPAO Sever al weeks apart, at different pain levels and after treatment with L-do pa. Caudate, thalamic, and anterior cingulate rCBF indices were measur ed. The caudate nuclei showed a 13% reduction in rCBF with increasing pain. The thalami and anterior cingulate showed a 7 and 6.6% increase in rCBF, respectively, with increasing pain. Compared to normal contro ls at rest, there was a decrease in caudate rCBF by 13% and an increas e in thalamic rCBF by 3%. Linear regression for the caudate nuclei rev ealed a significant reduction in rCBF (p < 0.05), as pain increased. T he daughter underwent an identical rCBF brain SPECT scan procedure at a high pain level induced by immobilization. Her scan showed a 12% red uction in caudate rCBF and a 1.2% increase in the anterior cingulate r CBF compared to healthy controls. The study supports the association b etween pain and decreased regional cerebral blood flow to the caudate nucleus as reported in fibromyalgia syndrome. There is increase in ant erior cingulate rCBF with increasing pain. Our findings also corrobora te that there is increased thalamic rCBF with pain stimulation.