COMPASSIONATE ALLOWANCE INFORMATION
X-LINKED MYOTUBULAR MYOPATHY
Myotubular Myopathy; X-Linked Centronuclear Myopathy; Centronuclear Myopathy ; Classic X-Linked Myotubular Myopathy
X-Linked Myotubular Myopathy (XLMTM) is a condition that primarily affects muscles used for movement (skeletal muscles) and occurs almost exclusively in males. Individuals with this condition have muscle weakness (myopathy) and decreased muscle tone (hypotonia) that is usually evident at birth. These muscle problems impair the development of motor skills such as sitting, standing, and walking. Affected infants may also have difficulties with feeding due to muscle weakness. Individuals with X-linked myotubular myopathy frequently do not have the muscle strength to breathe unassisted and must be supported with a machine to help them breathe (mechanical ventilation). Some individuals need breathing assistance only periodically, typically during sleep, while others require it continuously. Affected individuals may also have weakness in the muscles that control eye movement and other muscles of the face, absent reflexes, and musculoskeletal deformities or contractures.
Because of their severe breathing problems, individuals with XLMTM usually survive only into early childhood; however, some people with this condition live into adulthood.
DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM CODING
Diagnostic testing: Once clinical manifestations have occurred, the diagnosis is established by a combination of clinical examination, muscle biopsy, and genetic testing.
Physical findings: The physical findings of XLMTM may include hypotonia; difficulties with feeding due to muscle weakness; weakness in the eye muscles that control eye movement (ophthalmoplegia); absent reflexes (areflexia); an abnormal curvature of the spine (scoliosis); joint contractures of the hips and knees; and a large head with a narrow and elongated face.
ICD-9: 359.0 Congenital hereditary muscular dystrophy
ONSET AND PROGRESSION
XLMTM presents at birth with weakness, hypotonia and respiratory distress. Because of their severe breathing problems, individuals with severe XLMTM usually have a high incidence of death from respiratory failure in infancy or early childhood. Most males will fail to reach milestones and will not gain ambulation.
Treatment is supportive and symptomatic. Tracheostomy, G-tube feeding, and assistive communication devices are often required. Medical subspecialists should address specific medical complications (for example, scoliosis).
SUGGESTED PROGRAMMATIC ASSESSMENT*
Suggested MER for evaluation:
Clinical history and examination that describes the diagnostic features of the impairment including physical findings, family history, genetic testing, and muscle biopsy.
Suggested Listings for Evaluation:
103.02 C or D
Listing level musculoskeletal, respiratory, and/or neurological findings must be documented; diagnosis of XLMTM or lab testing results alone does not meet listing severity.
* Adjudicators may, at their discretion, use the Medical Evidence of Record or Listings suggested to evaluate the claim. However, the decision to allow or deny the claim rests with the adjudicator.