Restless legs syndrome may be divided in to two broad categories:-

  • Idiopathic (or primary) restless legs syndrome
  • Secondary restless legs syndrome

In the idiopathic group (which represents the largest of the two categories) there is no apparent underlying cause. Genetics plays a large part with a family history present in over 50% of people. The pathophysiology of the condition has not yet been fully established, however dysfunction of the dopaminergic system and problems with iron metabolism are thought to be implicated. Iron plays a crucial role in the metabolism of dopamine in the brain. The theory being that insufficient iron in the brain reduces dopamine function leading to restless legs. This insufficient level of iron in the brain can be present in people with normal peripheral blood levels of iron.

Secondary causes and associations are listed below:-

Pregnancy – especially third trimester
  • Usually resolves shortly after delivery
Approximate 20% incidence. Those affected in pregnancy have a fourfold incidence of developing it later in life
Iron deficiency
  • Present in up to ¼ of people with restless legs
Iron deficiency may precipitate or exacerbate symptoms
CKD
  • End stage
1/5 of people with end stage renal failure will experience restless legs
Drugs
  • Metoclopramide and prochlorperazine (dopamine receptor blockers)
  • Tricyclic antidepressants
  • Selective serotonin re-uptake inhibitors
  • Serotonin noradrenaline re-uptake inhibitors
  • Antipsychotics
  • Lithium
  • Antihistamines
  • Some antiepileptic drugs
  • Beta-blockers
Where appropriate and safe these drugs should be withdrawn. Symptoms should then be monitored to ascertain cause and effect
Some neurological conditions
  • Parkinson’s disease
  • MS
  • Peripheral neuropathy
  • Sciatica
May be associated
Dietary
  • Specifically excess of alcohol, caffeine and chocolate
Association unclear
Other
  • Rheumatoid Arthritis
  • Diabetes
  • Obesity
  • Fibromyalgia
Higher prevalence in these groups