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Diagnostics / RESTLESS LEGS SYNDROME | SleepTech

RESTLESS LEGS SYNDROME | SleepTech

Restless Legs Syndrome (Willis-Ekbom Disease)

RLS is a sensorimotor neurological disorder characterized by an irresistible urge to move the legs, usually accompanied or caused by uncomfortable sensations. It exhibits a strong circadian pattern.

The URGE Diagnostic Criteria

RLS is a clinical diagnosis based entirely on patient history. The four essential diagnostic criteria (URGE) are:

  1. Urge to move the legs, usually accompanied by uncomfortable/unpleasant sensations.
  2. Rest or inactivity (lying down, sitting) begins or worsens the symptoms.
  3. Getting up and moving (walking, stretching) partially or totally relieves the symptoms, for as long as the activity continues.
  4. Evening/nighttime appearance or worsening of symptoms compared to the daytime.

Iron Metabolism and the CNS

The primary pathophysiological mechanism of RLS involves impaired iron transport into the central nervous system and localized brain iron deficiency (particularly in the substantia nigra), despite potentially normal peripheral iron levels. This brain iron deficiency leads to dysfunction in dopaminergic pathways.

Clinical Guideline: Ferritin

Before initiating pharmacological treatment (like alpha-2-delta ligands), current guidelines strongly recommend checking a fasting serum ferritin panel. If ferritin is < 75 mcg/L (or transferrin saturation < 20%), oral iron supplementation (typically with Vitamin C to enhance absorption) is the first-line therapy.

RLS vs. PLMD

It is critical to distinguish RLS from Periodic Limb Movement Disorder (PLMD). RLS is a waking sensory diagnosis. PLMD is a polysomnographic diagnosis requiring objective evidence of Periodic Limb Movements in Sleep (PLMS) causing clinical disturbance (arousals/sleepiness). While ~80% of RLS patients have PLMS on a sleep study, isolated PLMS without RLS symptoms does not equal PLMD.

Detailed diagnostic criteria and physiological markers required to confirm this condition via polysomnography or clinical evaluation. Reliance on objective data is paramount.

Diagnostic Protocols

Refer to ICSD-3 classifications and ensure rule-out of confounding comorbidities prior to finalizing diagnosis.