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FOR CANADIAN RESIDENTS ONLY

BE RARE DISEASE AWARE: DELAYED AND DIFFERENTIAL DIAGNOSES ARE COMMON WITH NEUROMUSCULAR DISEASES

I was diagnosed with muscular dystrophy after years of tests and doctors’ visits, but something still didn’t feel right. I kept pushing for a specific diagnosis and I’m glad I did, because I finally have a name for my disease.

– Ana*

Delayed diagnosis is common

Diagnosis of neuromuscular diseases is delayed, often by many years. Even inherited diseases that are present, if not symptomatic at birth, often take decades to be diagnosed.1

In the case of Pompe disease, for instance, mean age at diagnosis for adults is mid 30s, with onset of symptoms often appearing 10 years before the diagnosis.2 For patients who have a treatable neuromuscular disease, this lost time is particularly concerning.

Delayed diagnosis occurs because of the subtle onset of symptoms over many years that mimic generalized fatigue and due to similarities and overlaps in clinical presentation with other neuromuscular diseases.3 This is why both documenting a thorough history and clinical assessments and making a prompt referral to the appropriate specialist can help save your patient valuable time.1

As one of about 7,000 rare diseases, Pompe disease affects an estimated 1 in 40,000 people, although its true prevalence in North America is unknown.4,5

Early detection makes a difference

When a patient has been suffering with muscle weakness and related symptoms – sometimes for years – and doesn’t know what is causing them, just having a diagnosis can be a relief. It gives the patient a name for their problem, and an idea of how to manage their life moving forward and prepare for the future. It may also allow them to seek treatment and work to manage their symptoms more effectively.

Focusing on diagnosis

Many disorders that present with muscle weakness and atrophy, including muscular dystrophy, inflammatory myopathies, spinal muscular atrophy and Pompe disease, have similar symptoms. There are many dozens of types of muscular dystrophy – each one involves an eventual loss of muscle strength, increasing disability and possible joint deformity (contractures, scoliosis, etc.).6

Two major groups of muscle disease include:7

  1. Muscle disorders that cause destruction of muscle fibers, leading to (usually progressive) muscle weakness and wasting
  2. Diseases that cause more of a functional defect than structural fiber degeneration (little wasting) such as metabolic myopathies or channelopathies

Diseases that progressively destroy muscle fibers fall into two main types:7

  1. Dystrophies: non-inflammatory degenerative conditions of muscle that are genetically determined, not effectively curable, and progressive
  2. Inflammatory myopathies: thought to be autoimmune in most cases

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Differential diagnoses in neuromuscular disease

Overlapping clinical presentations among neuromuscular diseases can make their differential diagnosis challenging. It is important to be aware of these diseases to help minimize diagnostic delays and expedite accurate diagnoses and management for patients.

Here are some neuromuscular diseases that may have shared signs and symptoms:3,6,8–24

The signs and symptoms listed in this chart are not an exhaustive list and may not be inclusive of all signs and symptoms that someone with these diseases may encounter.

References

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CK=creatine kinase; MD=muscular dystrophy.
* Fictitious patient.

Health information contained herein is provided for general educational purposes only. Your healthcare professional is the single best source of information regarding your health. Please consult your healthcare professional if you have any questions about your health or treatment.