Literature Review

AAN Guideline Provides Recommendations for Diagnosing Rare Forms of Muscular Dystrophy



A new guideline from the American Academy of Neurology (AAN) and the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) provides recommendations about how physicians should evaluate a patient to determine which genetic tests may best diagnose his or her subtype of limb-girdle or distal muscular dystrophy. Factors to consider include symptoms, family history, ethnicity, physical examination, and laboratory test results, according to the guideline, which was published in the October 14 issue of Neurology.

To develop the guideline, researchers reviewed all of the available studies on the disorders, which cause muscles to waste away. “These are rare muscle diseases that can be difficult to diagnose,” said lead author Pushpa Narayanaswami, MB, Assistant Professor of Neurology at Harvard Medical School in Boston and a fellow of the AAN and AANEM. “With an accurate diagnosis, unnecessary tests or treatments may be avoided. Knowing the specific subtype is important for getting the best possible care.”

Clinical Features May Aid Diagnosis
Certain clinical features and other information such as family history can help doctors determine a person’s subtype. “Looking at a range of clinical signs and symptoms—such as which muscles are weak and if there is muscle wasting or enlargement, winging out of the shoulder blades, early signs of contracted limbs, rigidity of the neck or back, or heart or lung involvement—can help doctors determine which genetic test to order,” said senior author Anthony A. Amato, MD, Professor of Neurology at Harvard Medical School and a fellow of the AAN and AANEM. “This [technique], in turn, can shorten the time to diagnosis and start of treatment while helping avoid more extensive and expensive testing.”

Clinicians should refer newly diagnosed patients with a subtype of limb-girdle muscular dystrophy and high risk of cardiac complications for cardiology evaluation, even if they are asymptomatic, according to the guideline. Although no cure for these disorders is available, patients and physicians can manage their complications. The guideline makes recommendations about treating and managing complications, which may include muscle symptoms, heart problems, and breathing problems.

A Role for Specialized Treatment Centers
“Before this publication, there were no care guidelines that covered both limb-girdle muscular dystrophy and distal muscular dystrophy and were based on the evidence,” said Julie Bolen, PhD, MPH, Team Lead and Epidemiologist at the National Center on Birth Defects and Developmental Disabilities within the Centers for Disease Control and Prevention in Atlanta. “We hope that this guideline will fill that gap for both the people who live with these rare disorders and the health care professionals who treat them.”

The guideline recommends that care for people with these disorders be coordinated through treatment centers specializing in muscular dystrophy. People with these disorders should tell their doctors about any symptoms such as tachycardia, premature heartbeats, shortness of breath, pain, or difficulty in swallowing, according to the authors. Treatments for these symptoms may be available. People should also talk to their doctors about exercises that are safe.

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