Sensorimotor disorder with an urge to move the legs at rest, relieved by movement, worse in the evening.
Also known as: RLS, Willis-Ekbom disease, restless leg syndrome
Overview
A sensorimotor disorder characterized by an irresistible urge to move the legs, usually accompanied by uncomfortable sensations, that begins or worsens at rest, is partially or fully relieved by movement, and is worse in the evening or at night (URGE mnemonic / IRLSSG essential criteria).
Epidemiology
Prevalence 5-10% in adults of European descent; lower in Asian populations. Female predominance ~2:1. Onset peaks before age 20 (primary, familial) and again in middle-late adulthood. ~40-60% report a positive family history.
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Question 1NeurologyMedium
A 54-year-old woman reports several months of an irresistible urge to move her legs that comes on each evening when she sits down to relax. She describes a deep, crawling, "creepy-crawly" sensation in her calves that improves when she walks around or stretches but returns once she lies still in bed. The symptoms delay sleep onset, and her husband notes that she repeatedly kicks her legs during the night. Her only medication is a daily multivitamin. Neurologic exam, including reflexes and sensation, is normal; serum ferritin is 18 ng/mL. Which of the following is the most likely diagnosis?
ARestless legs syndrome
BLumbar spinal stenosis
CPeripheral neuropathy
DNocturnal leg cramps
EAntipsychotic akathisia
Reveal answer & full explanation
Correct answer: A — Restless legs syndrome
ARestless legs syndrome✓
BLumbar spinal stenosis
CPeripheral neuropathy
DNocturnal leg cramps
EAntipsychotic akathisia
Why Restless legs syndrome is correct
The vignette meets all five IRLSSG essential criteria: an urge to move the legs with uncomfortable (crawling) sensations, onset at rest, relief with movement, an evening/night circadian pattern, and no alternative explanation.
Partner-witnessed nocturnal leg kicking reflects periodic limb movements of sleep, which commonly coexist with RLS.
A low serum ferritin (18 ng/mL) supports the diagnosis — brain iron deficiency is central to RLS pathophysiology, and ferritin should be checked and repleted toward >75-100 ng/mL even when hemoglobin is normal.
Why the others are wrong
Peripheral neuropathy — produces constant stocking-distribution paresthesias with objective sensory loss and reduced ankle reflexes, and neuropathic pain is often worse at night as well; what it lacks is the irresistible urge to move, the prompt relief with walking, and the onset triggered specifically by rest, and her sensation and reflexes are normal.
Antipsychotic akathisia — a generalized, whole-body inner restlessness that begins within days to weeks of starting or increasing a dopamine antagonist (antipsychotic, metoclopramide, prochlorperazine); pacing does relieve it temporarily, so the real discriminators are the whole-body distribution, the absence of a leg-localized crawling dysesthesia, the lack of a rest-dependent evening pattern, and the required drug exposure, which she does not have.
Nocturnal leg cramps — sudden, painful muscle contractions relieved by stretching the cramped muscle, without the persistent urge to move or the characteristic crawling sensation.
Lumbar spinal stenosis — tempting because it causes bilateral, position-dependent leg discomfort in middle-aged and older adults, but neurogenic claudication is provoked by standing and walking and relieved by sitting or bending forward, the reverse of her rest-induced symptoms that walking relieves; it also lacks the evening circadian pattern and the irresistible urge to move.
Question 2NeurologyMedium
A 44-year-old woman reports several months of a creeping, crawling urge to move her legs that begins each evening when she sits down to read and is relieved when she gets up to walk. The sensations keep her awake, and her husband notes that she kicks repeatedly during sleep. She takes no medications and drinks one cup of coffee daily. Neurologic exam, including reflexes and sensation, is normal. Laboratory studies show hemoglobin 13.1 g/dL, serum ferritin 35 ng/mL, and transferrin saturation 12%. Which of the following is the most appropriate initial management?
AFerrous sulfate
BPramipexole
CClonazepam
DGabapentin enacarbil
ECarbidopa-levodopa
Reveal answer & full explanation
Correct answer: A — Ferrous sulfate
AFerrous sulfate✓
BPramipexole
CClonazepam
DGabapentin enacarbil
ECarbidopa-levodopa
Why Ferrous sulfate is correct
This patient meets IRLSSG essential criteria for restless legs syndrome (urge to move, worse at rest, relieved by movement, worse in the evening), with partner-witnessed periodic limb movements.
Ferritin is the single most important test in RLS, and iron repletion is targeted first-line therapy whenever stores are low; guidelines recommend treating to a ferritin above 75-100 ng/mL even when hemoglobin is normal.
Her ferritin of 35 ng/mL with low transferrin saturation of 12% identifies a reversible, treatable contributor, so oral iron is the correct initial step before committing to chronic symptomatic drug therapy.
Why the others are wrong
Gabapentin enacarbil is an alpha-2-delta ligand and a legitimate first-line symptomatic agent, but it treats symptoms without correcting the low ferritin that should be repleted first in this scenario.
Pramipexole is a dopamine agonist; the AASM 2024 guideline conditionally recommends against routine first-line use because of augmentation and impulse-control disorder risk, and it does not address her iron deficit.
Clonazepam is a benzodiazepine reserved for select or pregnancy-related cases; it may aid sleep, but evidence of benefit for RLS symptoms is weak (the AASM 2024 guideline suggests against its use), and it does not treat the underlying iron deficiency.
Carbidopa-levodopa — a dopamine precursor that relieves RLS quickly and was long used for intermittent symptoms, but the AASM 2024 guideline conditionally recommends against its standard use, as it does for pramipexole, because levodopa carries the highest augmentation risk of the dopaminergic agents, and low iron stores further raise that risk, so correcting her ferritin comes first.
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Best understood as a brain iron deficiency state with altered central dopaminergic, glutamatergic, and adenosine signaling. CSF ferritin is low even with normal serum ferritin in many patients. Genetic variants in MEIS1, BTBD9, and PTPRD confer risk. Periodic limb movements of sleep (PLMS) commonly coexist.
Urge to move legs, sometimes arms, especially when sitting still or trying to fall asleep
Relief with walking, stretching, or rubbing the legs
Worse in evening and at night — circadian pattern
Insomnia and daytime fatigue
Partner reports periodic kicking or jerking during sleep (PLMS)
Signs / physical exam
Neurologic exam typically normal in primary RLS
Look for signs of peripheral neuropathy (stocking sensory loss, absent ankle reflexes) that may indicate secondary RLS
Pallor or cheilosis suggesting iron deficiency anemia
Classic findings
Adult with bedtime urge to move legs that resolves with walking, partner-witnessed leg kicks during sleep, and low ferritin.
Differential diagnosis
Peripheral neuropathy — Constant paresthesias, sensory deficit, reduced reflexes; not worse at rest or relieved by movement
Akathisia (drug-induced) — Whole-body inner restlessness, often briefly eased by pacing or rocking; lacks the evening/night worsening and leg-localized sensory discomfort of RLS; follows starting or increasing a dopamine antagonist (antipsychotic, metoclopramide) or SSRI
Nocturnal leg cramps — Painful sudden cramps relieved by stretching; not associated with urge to move
Anxiety with motor restlessness — Generalized restlessness, no temporal pattern, no relief with movement
Periodic limb movement disorder (PLMD) — Stereotyped movements during sleep without subjective urge; often coexists with RLS
Diagnostic workup
Diagnostic criteria
IRLSSG essential criteria (all 5): (1) urge to move legs, usually with uncomfortable sensations; (2) begins or worsens during rest/inactivity; (3) partially or totally relieved by movement; (4) worse in the evening or night; (5) not solely accounted for by another condition (cramps, positional discomfort, neuropathy).
Labs
Ferritin and transferrin saturation — the most important laboratory test; treat to ferritin >75-100 ng/mL
CBC, BMP, BUN/Cr (CKD evaluation)
TSH, fasting glucose/A1c, B12 if neuropathy suspected
Medication and substance review (SSRIs, antihistamines, dopamine antagonists, caffeine, alcohol)
Imaging
Routine imaging not indicated
Polysomnography reserved for diagnostic uncertainty or to evaluate PLMS / coexisting sleep apnea
Diagnostic algorithm
flowchart TD
A[Urge to move legs<br/>worse at rest/night,<br/>relieved by movement] --> B[Meet IRLSSG<br/>5 essential criteria]
B --> C[Check ferritin and TSAT,<br/>review medications,<br/>screen for CKD/<br/>pregnancy/neuropathy]
C --> D{"Ferritin ≤100 or<br/>TSAT <20%?"}
D -->|Yes| E["Oral or IV iron if ferritin ≤75<br/>or TSAT <20%<br/>IV iron only if ferritin 75-100"]
D -->|No| F["Initial therapy:<br/>alpha-2-delta ligand<br/>(gabapentin enacarbil,<br/>pregabalin)"]
F --> G{Refractory or<br/>severe?}
G -->|Yes| H["Dopamine agonist<br/>(low dose) OR<br/>low-dose opioid"]
H --> I{Augmentation<br/>on DA?}
I -->|Yes| J[Reduce DA,<br/>switch to gabapentinoid<br/>or opioid]
G -->|No| K[Continue,<br/>optimize sleep,<br/>recheck ferritin]
Stepwise management of restless legs syndrome with augmentation pathway.
Treatment
First-line
Iron repletion (AASM 2024): if ferritin ≤75 ng/mL or transferrin saturation <20%, give oral ferrous sulfate (325 mg every other day with vitamin C) or IV iron; if ferritin is 75-100 ng/mL, use IV iron only. IV ferric carboxymaltose is preferred (alternatives: low-molecular-weight iron dextran, ferumoxytol); IV iron sucrose is suggested for RLS with ESRD
Alpha-2-delta calcium channel ligands — gabapentin enacarbil 600-1200 mg, pregabalin 150-450 mg, or gabapentin 300-1200 mg at bedtime; preferred over dopamine agonists due to lower augmentation risk
Dopamine agonists — pramipexole 0.125-0.5 mg, ropinirole 0.25-4 mg, rotigotine patch 1-3 mg/24 h — NO LONGER recommended as standard/first-line therapy (AASM 2024 conditionally recommends against routine use) because of augmentation and impulse-control disorder risk; reserve for selected cases at lowest effective dose
Sleep hygiene; reduce caffeine, alcohol, nicotine; identify and stop aggravating medications when possible
Augmentation management
Augmentation = paradoxical worsening of symptoms with chronic dopamine agonist use (earlier onset, spread to arms, increased intensity)
Avoid escalating dopamine agonist dose, which worsens augmentation
Severe/refractory RLS
Low-dose long-acting opioids (oxycodone CR, methadone, buprenorphine) — reserved for refractory disease with shared decision-making about risks
Combination of alpha-2-delta ligand + dopamine agonist or opioid
Address coexisting OSA
Pregnancy
Optimize iron stores; oral iron preferred
Non-pharmacologic measures (stretching, leg massage, warm baths, pneumatic compression)
Avoid dopamine agonists and gabapentinoids in first trimester when possible; clonazepam or low-dose opioid only if severely impairing sleep
Second-line / adjunct
Pneumatic compression devices
Yoga, exercise, mindfulness
Treat coexisting OSA — CPAP can improve RLS symptoms
Complications
Chronic insomnia and daytime fatigue
Depression and anxiety
Augmentation with chronic dopamine agonist therapy
Impulse control disorders (pathologic gambling, hypersexuality, binge eating) with dopamine agonists
Opioid use disorder if opioids required long-term
PANCE pearls
Check ferritin in every patient with RLS — target >75-100 ng/mL even if hemoglobin is normal.
Gabapentinoids are increasingly favored over dopamine agonists as first-line pharmacotherapy due to augmentation risk.
Augmentation differs from tolerance: symptoms appear earlier in the day, are more intense, and spread to new body parts.
Diphenhydramine, metoclopramide, and SSRIs are common iatrogenic triggers — review medications carefully.
Severe iron-deficient RLS responds dramatically to IV iron — consider in patients with persistent symptoms despite oral therapy.
References
AASM 2024 — Winkelman JW et al. Treatment of restless legs syndrome and periodic limb movement disorder: an American Academy of Sleep Medicine clinical practice guideline. J Clin Sleep Med 2025;21(1):137-152.
IRLSSG — Allen RP et al. Restless legs syndrome/Willis-Ekbom disease diagnostic criteria: updated IRLSSG consensus criteria. Sleep Med 2014;15:860-873.
IRLSSG Iron Consensus — Allen RP et al. Evidence-based and consensus clinical practice guidelines for the iron treatment of RLS/WED. Sleep Med 2018;41:27-44.
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