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Ataxia
Bradykinesia
Choreoathetosis
Corticobasal Degeneration
Dyskinesias (Paroxysmal)
Dystonia
Essential Tremor
Hereditary Spastic Paraplegia
Huntington's Disease
Multiple System Atrophy
Myoclonus
Parkinson's Disease
Progressive Supranuclear Palsy
Restless Legs Syndrome
Rett Syndrome
Spasticity
Sydenham's Chorea
Tardive Dyskinesia
Tics
Tourette's Syndrome
Tremor
Wilson Disease
 

Diagnosis

Genetic testing
The discovery of the MECP2 has made possible the development of a test to aid in accurate diagnosis, detection of asymptomatic female relatives, and detection of the disorder before birth in families with an affected daughter.

Diagnostic evaluation
The diagnosis of RS is based upon a thorough clinical evaluation including a complete physical and neurologic assessment; detection of characteristic symptoms and findings; and a careful patient and family history. Diagnostic studies may also be conducted to eliminate possible neurodegenerative, neurometabolic, mitochondrial, or other disorders that may have similar symptoms (e.g., Angelman syndrome, Batten disease, organic acidemias, lysosomal storage diseases, etc.). These studies may include certain blood and urine tests; analysis of cerebrospinal fluid (CSF); neurophysiologic tests, such as electromyography (EMG) and Nerve conduction velocity (NCV) studies; and neuroimaging techniques, including computerized tomography (CT) scanning or magnetic resonance imaging (MRI).

Specialized studies may also be conducted to identify specific abnormalities associated with RS. For example, electroencephalography (EEG) may detect brain wave patterns that are unusually slow, characteristic of certain types of seizure activity, or associated with abnormal sleep patterns. X-ray studies that confirm relative shortening of certain bones (e.g., the fourth metatarsals or metacarpals, ulnae) may assist with the diagnosis of RS. In addition, physicians recommend that all RS patients undergo electrocardiography to detect heart conduction abnormalities (e.g., prolonged QT intervals) potentially associated with the disorder. Diagnostic evaluation may include 24-hour monitoring with a portable device known as a Holter monitor that records electrocardiograms while the patient performs normal daily activities. (The parents may also be asked to keep a diary tracking daily events for comparison with the ECG recordings.)

RS diagnostic criteria
The diagnostic criteria for RS were developed by study groups such as the Rett Syndrome Diagnostic Criteria Work Group (1988).

Symptoms and findings required for a diagnosis of classic RS:

  • Normal or apparently normal development until approximately age 6 to 18 months
  • Head circumference that is within normal limits at birth with subsequent slowing of head growth (acquired microcephaly)
  • Loss of purposeful hand movements, severe impairment of receptive and expressive language, and apparently severe mental retardation (that may be difficult to accurately assess due to motor and verbal impairments)
  • Development of uncontrolled, persistent (stereotypic) hand movements, including repeated hand clapping, mouthing, tapping, washing, and/or wringing
  • Impaired ability to coordinate movements required for walking (in those who are able to walk), resulting in a stiff, unsteady, widely based gait and possible "toe-walking"
  • Fine tremors of the torso and, possibly, the limbs, particularly during periods of agitation

Supportive criteria for a diagnosis of RS (not required for diagnosis but may be present or develop with age):

  • Breathing irregularities (e.g., periodic apnea and hyperventilation)
  • Abnormal brain wave patterns as seen by EEG, possibly including abnormal sleep patterns and seizure activity
  • Increasing motor impairment
  • Restricted movements of certain muscles due to progressively increased muscle rigidity (spasticity)
  • Permanent flexion or extension of affected joints in fixed postures (joint contractures)
  • Scoliosis
  • Chewing and swallowing difficulties
  • Constipation
  • Growth retardation
  • Teeth grinding (bruxism)
  • Unusually small feet
  • Poor blood circulation to the lower legs and feet (vasomotor disturbances)

In patients with classic RS, specialists may not consider the diagnosis confirmed until approximately age 2 to 5 years.

Authorities on RS have recommended revised inclusion criteria to allow for the diagnosis of atypical RS variants, including congenital onset, late regression, and milder (forme fruste) variants. For example, a diagnosis of atypical RS may be made if at least 3 of the primary criteria and 5 of the supportive criteria for classic RS are present. In addition, to improve detection and characterization of atypical RS male variants, some investigators suggest that less restrictive criteria should be considered when evaluating males with symptoms suggestive of RS.

Differential diagnosis and exclusion criteria
Diagnostic evaluation typically includes a series of tests to eliminate other disorders with similar symptoms, including certain inborn errors of metabolism, mitochondrial diseases, and genetic syndromes. The differential diagnosis of RS also includes cerebral palsy, autism, and other disorders characterized by mental retardation or seizures.

In addition, the detection of any of a number of specific findings enables physicians to rule out RS. These include confirmed prenatal growth retardation, an abnormally small head at birth (congenital microcephaly), evidence of acquired brain injury after birth, or visual impairment resulting from degenerative changes of the retinas or the nerves that transmit impulses from the retinas to the brain (optic nerves or second cranial nerves).