The diagnosis (clinical, four essential criteria)
Urge to move the legs (± uncomfortable sensations), worse at rest, relieved by movement, and worse in the evening/night — not solely explained by another condition. Often with periodic limb movements of sleep. Descriptions are vague (crawling, pulling, aching).
Secondary causes — always screen 🚩
Iron deficiency (check ferritin — aim >75 µg/L), pregnancy, renal failure, neuropathy, and aggravating drugs (antidepressants — esp. mirtazapine/SSRIs, antihistamines, dopamine antagonists/antiemetics). Correcting iron can be curative.
The discriminator that prevents error
RLS vs akathisia: akathisia is a drug‑induced (antipsychotic/antiemetic/SSRI) generalised inner restlessness, present at rest but not with the circadian, movement‑relieved, leg‑focused pattern of RLS. When a patient on an antipsychotic says "I can't sit still," think akathisia first — the management (reduce/stop the offending dopamine antagonist, propranolol) is opposite to escalating it.
Management (orientation)
Correct iron; α2δ ligands (gabapentin/pregabalin) or dopamine agonists (watch augmentation); withdraw aggravating drugs.
Pitfalls
- Missing low ferritin (a reversible cause).
- Calling drug‑induced akathisia "RLS" and mismanaging it.
Pearls
- 🎯 URGE–REST–EVENING–RELIEF + check ferritin.
- 🩺 Restlessness on an antipsychotic = akathisia until proven otherwise.
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