Restless leg syndrome

Definition /diagnostic criteria Restless leg syndrome (RLS) is characterised by an uncontrollable urge to move the legs, typically in response to uncomfortable sensations. These symptoms worsen during periods of rest and inactivity and are relieved by movement. The diagnosis is primarily clinical, based on the four essential criteria outlined by the International Restless Legs Syndrome Study Group (IRLSSG). There is no specific diagnostic test for RLS. The condition is also classified into primary (idiopathic) and secondary forms, the latter often associated with iron deficiency, pregnancy, or stage 5 chronic kidney disease.

RLS is estimated to affect approximately 5-10% of the UK population, with a higher prevalence in women and older adults. However, the severity of symptoms varies, and not all individuals seek medical help. The idiopathic form typically has an earlier onset and may have a genetic component, while the secondary form is usually associated with other medical conditions.

Diagnosis
Clinical features: The diagnosis of RLS is clinical, relying on patient-reported symptoms aligned with the IRLSSG criteria:

• An urge to move the legs, usually accompanied by uncomfortable and unpleasant sensations.
• The urge begins or worsens during periods of rest or inactivity.
• The urge is partially or totally relieved by movement.
• The urge and/or worsening occurs mainly in the evening or night.

Investigations: While there are no definitive tests for RLS, investigations aim to exclude other conditions and identify any potential secondary causes. Routine blood tests include serum ferritin, full blood count, blood glucose, renal function tests, thyroid function tests, folate, vitamin B12 levels and pregnancy testing where relevant.

Consider referring to a sleep clinic if you suspect a sleep disorder, and there is doubt about the diagnosis of RLS. Tests such as polysomnography can help to differentiate RLS from true sleep disorders

Treatment Non-drug treatments involve good sleep hygiene, avoidance of exacerbating factors such as caffeine and alcohol, and moderate exercise. Acute episodes of RLS may improve with heat/massage/walking and stretching. A medication review of drugs that can precipitate or exacerbate RLS should be conducted (e.g. antidepressants, some antiepileptics, antihistamines or beta blockers).

Iron supplementation is recommended in cases of iron deficiency.

Pharmacological treatments:

• Dopamine agonists as first-line therapy, such as pramipexole, ropinirole or rotigotine.
• Anticonvulsants like gabapentin or pregabalin may also be considered.
• Opioids and benzodiazepines are generally reserved for refractory cases.

Prognosis The natural history of RLS is variable. Primary RLS may have a chronic course with potential for periods of remission. Secondary RLS often improves with the treatment of the underlying condition. However, some pharmacotherapies, especially dopamine agonists, can lead to augmentation, where symptoms may occur earlier in the day and become more intense.