Neurological Sciences | 2019
Restless legs syndrome and its variants: a case report
Abstract
Dear Editor, Restless legs syndrome (RLS) is a common movement disorder, which affects 2–3% of the adult population [1]. Despite the fact that it has a substantial effect on the quality of life, it is often not recognized and left untreated for years [2]. The disorder is characterized by an urge to move the legs, usually combined with an uncomfortable feeling in the legs. These symptoms occur or worsen during periods of inactivity and are partially or totally relieved by movement [1]. Involvement of other limbs is described in relation to progression of the disease but is rarely described as the presenting symptom. A 49-year-old male patient was referred to our hospital with symptoms of stabbing pains and restlessness in both arms, mainly present in the evening and during the night, for about 10 years. When the complaints were severe, he felt an urge to move his arms which resulted in a slight relief of the symptoms. He did not experience any symptoms in his legs. He had already visited several doctors over the past years, and 2 years ago, the rheumatologist diagnosed him with fibromyalgia. He did not use any medication. Neurological examination revealed no abnormalities. Iron levels and renal function were within normal limits. Hemoglobin (Hb) was 9.5 mmol/l. Based on his symptoms and the fact that they complied with the diagnostic criteria used for RLS, we prescribed a low dose of pramipexol 0.125 mg once a day. Shortly after starting this medication his symptoms disappeared. The complaints of the arms were completely resolved and he no longer had difficulties falling asleep. A 47-year-old man was referred to our outpatient clinic because of a tingling sensation in the tongue for several months. Tightening of the jaws gave some relieve of these symptoms. When the tingling sensation in his tongue got worse, he also experienced symptoms of restlessness in his legs. Complaints were most prevalent in the evening and during periods of rest. The patient had been known to have diabetes for several years, for which he used insulin. He did not express any symptoms indicating polyneuropathy. However, the Achilles tendon reflexes were low and vibration sense was slightly impaired. No other abnormalities were found when examining the patient. Additionally, no abnormalities were seen when visually inspecting the tongue. The serum iron level was 15 μmol/l. Treatment with pramipexol proofed to be successful. The symptoms disappeared entirely with a dose of 0,75 mg slow release once a day. A hypodopaminergic state in relation to central nervous system iron deficiency has long been proposed in the pathophysiology of RLS [3]. This theory was based on clinical observations which show that patients with RLS improve with dopaminergic medication [4]. Alternatively, recent research has proposed a hyperdopaminergic state in RLS patients. Increased levels of dopamine are superimposed to the normal circadian changes in dopamine availability [3]. Increased presynaptic and synaptic dopamine levels are created by iron defic iency through hypoxic pathway act ivat ion. Consequently, a postsynaptic downregulation of dopamine receptors occurs, which overcorrects for the normal nocturnal decrease in dopamine, resulting in RLS symptoms [3]. It has also been shown that there are genetic predispositions which influence the iron-dopamine system and contribute to the development of RLS [2]. Dopaminergic cells in the hypothalamus send inhibitory signals to the dorsal raphae nucleus, causing a decrease of sympathetic excitation in the spinal cord. Dopaminergic dysfunction may thereby cause a decreased inhibition, resulting in a higher sensory input to the cortex, increased sensory activation of the reflex arc of the spinal cord * Amée F. Wolters [email protected]