Restless abdomen: a phenotypic variant of restless legs syndrome

A diagnosis of restless legs syndrome (RLS) requires an urge to move the legs in combination with sensory leg discomfort. Localization of the symptoms to other body areas in the absence of leg involvement is not recognized as part of the phenotypic spectrum of RLS. We describe 3 patients who presented with sensorimotor symptoms confined to the abdominal wall and, with the exception of not involving the legs, satisfied the primary and secondary diagnostic criteria for RLS.

Patients underwent detailed clinical history, video-polysomnography, abdominal imaging, and serologic and genotyping assessment.

Unpleasant abdominal symptoms emerged at night during periods of rest and were accompanied by an urge to move and temporized by movement. Patients reported sleep onset and sleep maintenance insomnia due to their abdominal symptomatology. Abdominal imaging was normal. Secondary features included periodic leg movements of sleep (PLMS), and dramatic symptom amelioration with the D(2)-D(3) dopaminergic agonist pramipexole. Two subjects were anemic. Conventional RLS emerged in one subject and resolved after dose escalation. Each subject was homozygous for the most common RLS/PLMS-associated risk allele in the BTBD9 gene.

Our observations indicate that the restricted abdominal symptomatology manifest in our subjects represents a phenotypic variant of RLS. Physicians should be vigilant to the existence of this unique phenotype when encountering subjects who present with insomnia and abnormal abdominal sensations. Our experience emphasizes the importance of supportive clinical features in rendering a correct diagnosis such that the most cost-effective workups and treatment can be realized.