Diagnostic Criteria and Differential Diagnosis of Restless Legs Syndrome

Core Diagnostic Criteria (American Academy of Sleep Medicine)

• Restless Legs Syndrome (RLS) is diagnosed only when all five criteria are met:

Distinguishing Features from Common Mimics

Muscle Cramps (American Academy of Sleep Medicine)

• Sudden, painful, localized muscle contractions that are sharp rather than diffuse; no urge to move, and relief is not obtained with gentle movement.
• No consistent circadian pattern; pain resolves spontaneously or after stretching. 1

Peripheral Neuropathy (American Geriatrics Society)

• Prominent numbness and tingling (“pins and needles”) that are constant and not related to rest or activity.
• Absence of circadian variation; abnormal neurologic examination (reduced sensation, absent reflexes, weakness).
• Frequently associated with diabetes, renal disease, or other systemic conditions. 3

Intermittent Claudication (American Geriatrics Society)

• Exercise‑induced calf cramping or aching that worsens with walking and improves with rest.
• No circadian pattern; physical exam may reveal diminished peripheral pulses or vascular bruits. 3

Osteoarthritis (American Academy of Sleep Medicine)

• Pain localized to specific joints (knee, hip) that worsens with activity and improves with rest; no circadian pattern.
• Joint examination shows crepitus, limited range of motion, and tenderness; morning stiffness improves during the day. 1

Deep Vein Thrombosis (American Academy of Sleep Medicine)

• Unilateral leg swelling, warmth, and tenderness; pain is constant and not relieved by movement.
• Positive Homan’s sign or palpable cord; no circadian variation.
• In contrast, primary RLS typically involves both legs (often bilaterally). 2

Positional Discomfort (American Academy of Sleep Medicine)

• Discomfort is instantly relieved by changing position without the need for continued movement; no urge to move once comfortable; no circadian pattern. 1

Leg Edema / Venous Stasis (American Academy of Sleep Medicine)

• Visible swelling that worsens throughout the day, described as aching or heaviness rather than an urge to move.
• Improves with leg elevation; examination shows pitting edema and varicosities. 1

Diagnostic Pitfalls and Algorithm (American Geriatrics Society)

• If only the four symptom criteria are assessed without excluding mimics, ≈16 % of patients without RLS are misclassified as having RLS. 1
• Recommended sequential questions when evaluating leg discomfort:

Typical Clinical Characteristics of Primary RLS (American Geriatrics Society)

• Bilateral involvement is usual, though severity may be asymmetric.
• Sensations are described as deep‑inside the legs, not superficial.
• Sleep disruption is common, leading to insomnia and daytime sleepiness.
• In severe cases, symptoms may extend to the arms or trunk.
• Physical examination is typically unremarkable. 3

When to Suspect Secondary RLS (American Geriatrics Society)

• Serum ferritin < 50 ng/mL – check in all RLS patients.
• Presence of end‑stage renal disease.
• Pregnancy, especially in the third trimester.
• Use of medications known to exacerbate RLS (e.g., SSRIs, tricyclic antidepressants, dopamine antagonists, antihistamines).
• Abnormal neurologic findings suggestive of peripheral neuropathy. 3