Regional cerebral blood flow in a patient with restless legs syndrome exhibiting pramipexole-induced hypersexuality

Impulse control disorders (ICDs), including hypersexuality, are associated with adverse effects of dopamine agonists, such as pramipexole, particularly in the treatment of Parkinson's disease and restless legs syndrome (RLS). The underlying mechanisms remain unclear in ICDs in patients with RLS, and no neuroimaging studies have investigated regional cerebral blood flow (rCBF) changes in RLS patients with ICDs.

A 60-year-old man with RLS developed hypersexuality after initiating pramipexole at 0.5 mg/day. He exhibited inappropriate sexual behaviors toward hospital staff. Single-photon emission computed tomography revealed increased rCBF in the bilateral orbitofrontal cortex and medial frontal cortex, as well as in the left striatum and thalamus. The hypersexuality gradually resolved following pramipexole discontinuation.

This case suggests that pramipexole-induced hypersexuality in RLS may be linked to increased rCBF within the mesocorticolimbic network, including orbitofrontal cortex, medial frontal cortex, and striatum, thereby impairing impulse control. Despite the relatively low dose of pramipexole (0.5 mg/day), individual susceptibility factors, such as depressive symptoms and intellectual disability, may have contributed to ICD onset. Given the lack of prior studies examining rCBF in RLS patients with ICDs, further research is needed to elucidate the pathophysiological mechanisms and risk factors associated with pramipexole-induced ICDs in RLS.