Paediatric neuromuscular disorders - what are they, and how can early diagnosis help?

Professor Monique Ryan examines paediatric neuromuscular disorders (NMDs), including types, signs and symptoms, and the importance of early interventions in ensuring best possible patient outcomes.

 There are a range of paediatric neuromuscular disorders (NMDs). These genetic or acquired conditions affect the peripheral nervous system; the muscles, neuromuscular (nerve-muscle) junction, peripheral nerves and motor-nerve cells, causing weakness and damage.

 NMDs vary in severity and affect each person individually. Some NMDs are life threatening. Respiratory (breathing) muscles are often affected, cardiac and orthopaedic complications are frequent, and delayed motor development is virtually universal. Affected children need specialist care as soon as possible to stay as well as possible.

 Some paediatric NMDs are:

  • SMA -Spinal muscular atrophy
    SMA is a complex neurological condition, similar to motor neuron disease, affecting the motor neurons of the spinal cord and causing hypotonia, muscle weakness, and delayed motor milestones. SMA is divided into three types dependent largely on the age of onset of symptoms. The earlier the onset, the more severe and debilitating, the course of the disease. It is particularly important to address symptoms of infantile SMA as quickly as possible as a new treatment is available. This medication halts the progression of the disease in most cases.
  • DMD -Duchenne muscular dystrophy
    DMD is the most common childhood muscular dystrophy. DMD affects approximately 1 in 5000 boys and can be carried by girls. Characterised by progressive loss of muscle strength and bulk, DMD usually presents when boys are 2-4 years old, with motor delay, slow running and difficulty arising from the floor. This condition is progressively debilitating, to the point of boys being wheelchair-dependent by their teenage years. Treatment of DMD is aimed at reducing the symptoms of weakness and keeping children as healthy as possible for as long as possible.
  • CMT -Charcot-Marie-Tooth disease
    CMT is an umbrella term for a range of inherited genetic disorders that affect the peripheral nervous system. The effects of Charcot-Marie-Tooth disease can vary widely and symptoms usually develop gradually. Pes cavus, foot drop and gait abnormalities are usually first seen in childhood or during the teenage years. The legs are most usually affected first, and over time muscles become weaker and harder to control. People with CMT have normal learning abilities and a normal life expectancy.
  • FSHD -Facioscapulohumeral dystrophy
    FSHD can be variable in severity and begin at any age from infancy to adulthood. FSHD causes progressive muscle weakness and loss of function, but is not life limiting. FSHD is named for those areas of the body where muscle weakness is usually first noticeable in patients: Facio (face), Scapular (back/shoulder), Humeral (upper arm) with some people also experiencing weakness in their trunk and lower limbs. Treatment of FSHD is based around supportive therapies to help maintain and facilitate bodily function.

Early diagnosis
Neuromuscular diseases are chronic and have a large impact on patients and their families. While there is no cure for a neuromuscular disorder, there are an increasing number of therapies and treatments available that can improve children’s quality of life and support physical functions. Earlier diagnosis and treatment of neuromuscular disorders optimises long-term function.

 The presentation of neuromuscular disorders in infancy and childhood can be varied, and their diagnosis can be challenging. GPs and maternal and child health nurses have a critical role in early diagnosis, which gives children affected by neuromuscular disorders the chance of best possible outcomes. The most important thing for GPs and maternal and child health nurses to remember is that if a NMD is suspected, early referral to a specialist paediatric neurologist is critical.

 Not all signs and symptoms will be present in any one case, but these are important diagnostic markers requiring further investigation and urgent referral to a paediatric neurologist.

Signs and symptoms of NMDs
In babies:

  • Floppiness or hypotonia
  • Little or no head control
  • Absent reflexes
  • Weak cry
  • Feeding difficulties
  • Abnormal breathing
  • Recurrent choking or apnoeic episodes
  • Delayed milestones of rolling, sitting, crawling

As children get older:

  • Muscle weakness in limbs
  • Toe walking
  • Facial weakness
  • Tongue fasciculations
  • Shoulder pain and or weakness
  • Legs giving way and tripping (foot drop)
  • Falling and tripping
  • Weakness, difficulty getting out of a chair
  • Difficulty rising from the floor

 The management of NMDs is complex and requires a multidisciplinary team approach. The team includes neurologists, nurses, occupational therapists, physiotherapists, social workers, speech therapists and neuropsychologists. All families should receive genetic counselling and psychosocial support.

 If you suspect a neuromuscular disorder, REFER IMMEDIATELY for an urgent appointment with your local paediatric neurologist (or local paediatrician if not available).

 To learn more about paediatric NMDs in just one CPD hour click here.

Professor Monique Ryan Professor Monique Ryan is head of the multidisciplinary RCH Neuromuscular Clinic and the RCH Neuromuscular Research Unit, which includes a growing team of clinicians and researchers aimed at improving diagnosis and management of children affected by muscular dystrophies, myopathies and neuropathies.