Chapter 47 - Functional neuroimaging of dopamine, iron, and opiates in restless legs syndrome

Summary

The rapid efficacy of dopaminergic drugs in restless legs syndrome (RLS) treatment can be taken as evidence for the role of dopaminergic neurotransmission. To evaluate the hypotheses that dysfunctional dopaminergic, opioidergic, or iron systems are involved in the pathophysiology of RLS, functional neuroimaging studies have been performed using single photon emission computed tomography (SPECT), positron emission tomography (PET), and, more recently, magnetic resonance imaging (MRI). Imaging studies in RLS patients have detected changes in brain iron metabolism, which did not show a consistent association with reduced cerebrospinal fluid ferritin levels. Imaging studies of the opioidergic system are still limited, but available data point to an involvement of opioids in the pathophysiology of RLS. With regard to RL symptomatology, it is of particular interest that the dopamine system is involved in the modulation of nociceptive signals, which may contribute to the perception of pain and symptoms of restlessness.