Diagnosis of Restless Legs Syndrome

Diagnostic Evaluation of Restless Legs Syndrome

Restless legs syndrome is diagnosed primarily by conducting a careful patient history using the four minimal criteria established in 1995 by the International Restless Legs Syndrome Study Group (IRLSSG). Patients are diagnosed with restless legs syndrome only if they meet all four of these criteria:

  • A compulsory desire or urge to move the limbs usually associated with paresthesia (an abnormal sensation such as burning, pricking, tickling, or tingling). The sensations are not perceived as painful, and are rarely felt in the feet.
  • The urge to move legs or the onset of paresthesia is initiated or worsens during periods of rest or inactivity, such as sitting or lying down.
  • Symptoms are partially or temporarily relieved by movement, such as pacing or stretching
  • Symptoms are more severe during the evening or night (usually between 6 PM and 4 AM) than in the day or they occur only at night.

Clinical features which support the diagnosis of restless legs syndrome but are not essential include:

  • Positive family history of restless legs syndrome
  • Periodic limb movements (during sleep or while awake)
  • Positive response to dopaminergic drugs (reduction or cessation of symptoms)

Features associated with restless legs syndrome and noted in many patients include:

  • Typically a chronic and progressive condition
  • Physical examination is normal (for idiopathic restless legs syndrome)
  • Sleep disturbances including problems falling asleep, staying asleep, and poor quality of sleep

The diagnosis of restless legs syndrome can be made based on clinical features alone including the history of the patient and the lack or absence of abnormal findings. If the diagnosis of restless legs syndrome is clear from the clinical presentation, there is no need to test for PLMS since it is known that up to 80% of patients with restless legs syndrome suffer from PLMS as well. On the other hand, if PLMS is present and the 4 criteria mentioned above for the diagnosis of restless legs syndrome are not met, then the physician must look further for other causes of PLMS.

The diagnostic criteria for children slightly differ according to conclusions of a workshop on restless legs syndrome sponsored by the National Institutes of Health and include:

  • All 4 adult criteria
  • Description in the child's words of the leg discomfort OR
  • All 4 adult criteria AND two of the following three criteria:
    • Sleep disturbances
    • Family history of restless legs syndrome (parent or sibling)
    • Polysomnographic evidence of 5 or more PLMS per hour of sleep

Diagnosis of childhood restless legs syndrome is also more challenging since the clinician must differentiate restless legs syndrome from other causes of lower leg discomfort that children can experience, such as growing pain, sore muscles from overuse.

The complete diagnostic evaluation of a patient with symptoms of restless legs syndrome usually includes:

  • Patient history and physical examination
  • Neurological evaluation
  • Laboratory studies
  • Related diagnostic studies

Patient History and Physical Examination

The patient interview is an important opportunity for the doctor to establish the presence of the criteria for restless legs syndrome. In addition to a careful history of the signs/symptoms, patients with suspected restless legs syndrome usually undergo a physical examination during which the physician should rule out other medical conditions which may be causing restless legs syndrome.

Neurological Evaluation

A neurological evaluation of patients with suspected restless legs syndrome usually includes:

  • Spinal cord and peripheral nerve function
  • Sensory and motor function
  • Evaluation of deep tendon reflexes
  • Evaluation of muscle strength
  • A vascular examination is also recommended in order to rule out deep vein thrombosis

Laboratory Studies

Laboratory studies that may be conducted in patients with suspected restless legs syndrome include:

  • Complete blood count (CBC)
  • Iron
  • Ferritin
  • Vitamin B12
  • Folate
  • Thyroid function test
  • Kidney function test
  • Liver function test
  • Erythrocyte sedimentation rate
  • Peripheral nerve conduction studies (to rule out peripheral neuropathy)

Related Diagnostic Studies

Related diagnostic studies that can confirm the diagnosis of restless legs syndrome include:

  • Suggested Immobilization Test (SIT) - This test has been proposed by the American Academy of Sleep Medicine as a supplementary test to assess subjective and motor components of restless legs syndrome.

  • Polysomnography - Polysomnography is an overnight sleep test performed in a hospital or sleep center which allows doctors to continuously monitor various physiological activities during sleep. Polysomnography is usually not necessary to reach a diagnosis of restless legs syndrome but may be considered if sleep is still disrupted even after treatment of restless legs syndrome. Factors that are evaluated during polysomnography include:

    • brain electrical activity
    • eye movement
    • jaw movement
    • leg muscle movement
    • airway and respiration