Does restless legs syndrome cause balance problems or true leg weakness?

Restless Legs Syndrome Does Not Cause True Balance Problems or Leg Weakness

RLS is purely a sensorimotor disorder characterized by an urge to move the legs with uncomfortable sensations—it does not cause actual muscle weakness or balance impairment. 1 If a patient presents with true leg weakness or balance problems, you must look for alternative or coexisting diagnoses.

What RLS Actually Causes

RLS produces specific symptoms that are distinct from weakness or balance dysfunction:

• An irresistible urge to move the legs accompanied by uncomfortable sensations (crawling, aching, tingling) 1, 2
• Worsening with rest or inactivity (sitting, lying down) 1
• Relief with movement (walking, stretching) that lasts only as long as the activity continues 1
• Circadian pattern with symptoms appearing or intensifying in evening/night 1, 2

The physical examination in primary RLS is characteristically unremarkable—there should be no objective neurological deficits. 1

Critical Differential Diagnosis When Weakness or Balance Issues Are Present

If your patient has actual leg weakness or balance problems, the American Geriatrics Society emphasizes you must perform a thorough neurological examination to identify these distinct conditions:

• Peripheral neuropathy (which can cause sensory deficits AND true weakness) 1, 3
• Radiculopathy (which produces dermatomal weakness patterns) 1
• Vascular disease/intermittent claudication (which causes exercise-induced weakness) 1, 3
• Spinal cord lesions (which can cause both RLS-like symptoms AND objective weakness) 4

Secondary causes like vitamin B12 deficiency can produce extensive demyelination causing paresthesias, numbness, muscle weakness, abnormal reflexes, and gait disturbances that overlap with RLS presentations but include true neurological deficits. 5

The Key Clinical Distinction

The American Academy of Sleep Medicine's fifth essential diagnostic criterion states: symptoms cannot be solely accounted for by another medical or behavioral condition. 1, 6 Without proper differential diagnosis, 16% of patients who do not have RLS will be misclassified. 6

If objective weakness or balance impairment exists on examination, this is NOT RLS—it is either a mimic or a coexisting condition. 1

What to Do Clinically

When evaluating a patient with leg complaints:

1. Perform a thorough neurological examination looking specifically for motor weakness, sensory deficits, abnormal reflexes, or gait abnormalities 1

2. Check serum ferritin immediately (values <50 ng/mL indicate iron deficiency-related RLS) 1, 3

3. If any objective neurological findings are present, pursue workup for peripheral neuropathy, radiculopathy, or other structural/metabolic causes 1, 3

4. Consider vitamin B12 levels in patients presenting with late-onset symptoms (fifth to seventh decade) without family history, especially since neurological symptoms can occur without hematological abnormalities 5

The bottom line: RLS patients should have normal strength and balance on examination. 1 Any deviation from this warrants investigation for alternative diagnoses.