Neuromuscular disorders

What are Neuromuscular Disorders?

Neuromuscular disorder (NMD) is a very broad term encompassing a range of conditions that impair the functioning of the muscles, either directly, being pathologies of the voluntary muscle, or indirectly, being pathologies of the peripheral nervous system or neuromuscular junctions. Other spinal cord or brain diseases are not considered “neuromuscular” diseases.

NMD affect the nerves controlling voluntary muscles. Voluntary muscles are the ones that can be controlled such as those in arms and legs. Nerve cells, also called neurons, send the messages that control these muscles. When the neurons become unhealthy or die, communication between the nervous system and muscles breaks down. As a result, muscles weaken and waste away. The weakness can lead to twitching, cramps, aches and pains, and joint and movement problems. Sometimes it also affects heart function and the ability to breathe.

Examples of NMD include:

• Amyotrophic lateral sclerosis – Motor Neurone Disease
• Multiple sclerosis
• Myasthenia gravis
• Spinal muscular atrophy.

Many NMD are genetic, which means they run in families or there is a gene mutation for example in muscle dystrophies. Sometimes, an immune system disorder can cause them as in myasthenia.

Incidence

Some NMD are very rare. A neurocience nurse may not meet a patient with MND in their clinical career.

Presentation

Patients with NMD can have weakness, loss of muscle bulk, muscle twitching, cramping, numbness, tingling, and a host of other symptoms. Problems with the nerve-muscle junction can also cause droopy eyelids, double vision, and weakness that worsen with activity. Some NMD can also cause difficulty with swallowing and sometimes with breathing.

The principle symptoms and signs of NMD may include the following are:

• muscular weakness
• rigidity
• loss of muscular control
• myoclonus (twitching, spasming, cramping)
• myalgia (muscle pain)
• swallowing difficulties
• breathing difficulties
• fatigue
• changes in facial appearance
• visual disturbances.

Diagnosis

Diagnosis of NMD disorders include a number of approaches:

• detailed questioning of patients to determine the signs, symptoms and onset
• consideration of drug and social history as drugs therapeutic and reactional and toxins can be a cause of NMD with drug induced myopathies or myasthenia being aggravated by drugs
• musculoskeletal and neurologic examinations
• observation assessing the muscle considering bulk, possible atrophy or loss of muscle tone 
• testing levels of various chemicals and antigens in the blood such as creatine kinase and myoglobinaemia which are evidence of muscle fibre breakdown.  Test for antibodies as in myasthenia
• diagnostic tests including electromyography (measuring electrical activity in muscles) and nerve conduction studies
• genetic testing as many neuromuscular conditions are inherited
• age is an important consideration for example the symptoms of Duchenne muscular dystrophy never appear for the first time after the age of five years whereas occulopharyngeal dystrophy and inclusion body myositis do not present before middle age. Myasthenia can affect any one from birth to 100 years.

Management

Most NMD have no cure. The goal of treatment is to improve symptoms, increase mobility and lengthen life. In terms of treatment for NMD, exercise might be a way of managing them, as NMD individuals can gain muscle strength. In a study aimed at results of exercise, in muscular dystrophy and Charcot-Marie-Tooth disease, the later benefited while the former did not show benefit; therefore, it depends on the NMD. Regardless of the condition regular exercise (little and often if that is all that is possible) and a healthily life style is recommended to remain as physically fit as possible to avoid other health care complications. Other management routes for NMD should be based on medicinal and surgical procedures, again depending on the underlying cause.  

All NMD require long term follow up and the support of a wide MDT including physiotherapy, respiratory services, occupational therapy, clinical psychology, orthotics, wheelchair services. It is of benefit to see a clinical specialist on a regular basis but the GP is central to the care of the patient taking responsibility for the day to day management of the NMD under the guidance of the specialist. 

It is important to remember that any change in the patients’ condition is not always attributed to the NMD and left to await specialist review and intervention. GPs and the MDT always need to actively consider clinical presentation outside the progression of the NMD to ensure patients remain in optimal health and can live well with their chronic condition.

A particular challenge for individuals with some NMDs is that the impact of their condition is variable. The impact of myasthenia and muscle fatigability is not understood with individuals being meet with disbelief that one moment they were able to do something and now they cannot. The impact of many muscular dystrophies are not readily obvious but impacts on daily life. A key part of proactive management is education ensuring those working with or supporting individuals with NMD understand the unique impact of their condition and support they appropriately NMD physically and psychologically to live well.

Role of the nurse in NMD care

All nursing staff have important roles and responsibilities when caring for individuals with NMD. These include:

• understanding NMD aetiology
• proactively managing the ongoing the physical impact of NMD on individuals’ daily life
• providing psychosocial support to patients and families living with NMDs
• reducing morbidity and preventing mortality for individuals with NMD enabling them to live well
• engaging and co-ordinating multi-disciplinary team assessment and input.