Standards of Care and Follow-up

In most neuromuscular disorders what determines outcome after diagnosis is whether care is delivered regularly and with anticipation. The headings below apply to most patients regardless of diagnosis; frequencies are adjusted to the condition and stage.

Respiratory care

Respiratory failure develops insidiously and daytime examination may be normal. The first disturbance is nocturnal hypoventilation during REM sleep. Warning features include morning headache, daytime sleepiness, fatigue, poor appetite, difficulty concentrating, frequent and prolonged respiratory infections, a weak cough, frequent night waking and failure to gain weight.

• Monitoring: spirometry sitting and supine, peak cough flow, overnight oximetry and capnography, and sleep study where indicated.
• A fall in vital capacity on lying flat is one of the earliest and most practical indicators of diaphragmatic weakness.
• Interventions: manual and mechanical cough assistance, lung volume recruitment, nocturnal non-invasive ventilation and, as disease advances, extension of support into the day.
• Mechanical cough assistance is one of the most practical interventions for reducing pneumonia and hospital admission, and it is often considered late.
• Infection: seasonal influenza and pneumococcal vaccination, and RSV prophylaxis where appropriate. Respiratory infection in a neuromuscular patient is managed early and actively.

Cardiac surveillance

Cardiac involvement occurs in many neuromuscular disorders and is asymptomatic, because the child cannot exert to a level that stresses the heart. Surveillance is therefore scheduled rather than symptom-driven.

• Dystrophinopathies: regular echocardiography and ECG from diagnosis, with cardiac MRI at older ages; cardioprotective treatment may be started before symptoms. Carrier mothers and sisters are also followed.
• Myotonic dystrophy: primarily conduction disease and arrhythmia; regular ECG and Holter monitoring where indicated. There is a risk of sudden death.
• Pompe disease (infantile): hypertrophic cardiomyopathy.
• Some limb-girdle subtypes (FKRP, LMNA, sarcoglycanopathies) and some congenital muscular dystrophies.
• Cardiac involvement is not typical in classic 5q SMA.

Orthopaedic care and the spine

• Contractures: Achilles, knee and hip flexors, elbow, wrist. Prevention is easier than treatment: regular stretching, night splints, appropriate positioning and supported standing.
• Scoliosis: common and progressive, particularly in non-ambulant patients; it impairs sitting balance, comfort and respiratory function. Surgical decisions weigh curve magnitude, rate of progression and respiratory and cardiac reserve together, and it is important to decide before respiratory reserve is lost.
• Hips: risk of subluxation and dislocation in non-ambulant patients; regular examination with imaging as required.

Nutrition and bone health

There is a two-way risk: undernutrition and aspiration in patients with bulbar involvement, and excessive weight gain in immobile patients on steroids. Regular weight and height measurement, swallowing assessment, management of constipation and surveillance for reflux are required. Where oral intake is insufficient, gastrostomy should not be delayed; a late gastrostomy coincides with the period when respiratory reserve has fallen and procedural risk is higher.

Immobility, lack of sun exposure and corticosteroid treatment combine to increase fracture risk substantially. Vertebral fractures may be silent; back pain or loss of height should be investigated. Vitamin D status is monitored and replaced.

Rehabilitation

The aims are to preserve joint range, prevent contracture and maintain function and participation: regular stretching and positioning, supported standing and weight bearing, appropriate orthoses, timely adjustment of wheelchair and seating, work on hand function and activities of daily living, and communication support.

Anaesthetic and surgical risk

Neuromuscular patients can experience unexpected and severe complications during elective procedures such as dental treatment, sedation for imaging or orthopaedic surgery. This heading should be recorded prominently in the notes.

• Suxamethonium is contraindicated; it can cause hyperkalaemic cardiac arrest and rhabdomyolysis.
• Inhalational anaesthetics can precipitate rhabdomyolysis and malignant-hyperthermia-like reactions in dystrophinopathies and RYR1-related myopathies; total intravenous anaesthesia is preferred.
• RYR1 mutations carry true malignant hyperthermia susceptibility.
• In a patient with weak respiratory muscles, difficult extubation and postoperative respiratory failure should be anticipated.
• In myotonic dystrophy, sensitivity to anaesthetic agents and opioids is increased and the risk of postoperative apnoea is high.
• Preoperative cardiac assessment is required in patients with cardiac involvement.

Presentation to the emergency department

Neuromuscular patients are assessed in the emergency department by a team unfamiliar with their condition. Common errors include:

• Giving high-flow oxygen alone. Hypoxia is usually the result of hypoventilation; saturation improves while carbon dioxide continues to accumulate. If oxygen is given, ventilatory support must be considered alongside it.
• Interpreting respiratory distress as panic or anxiety.
• Overlooking a weak cough and discharging the patient without secretion clearance.
• Missing a surgical abdomen because guarding is weak as a result of muscle weakness.
• Giving standard doses of sedatives or opioids; the risk of respiratory depression is high.

Functional outcome measures

Objective follow-up is needed both for clinical decisions and for assessing response to treatment. A scale appropriate to the condition and motor level is chosen for each patient and the same scale is then applied consistently.

• CHOP-INTEND: severely affected infants, particularly SMA type 1.
• HINE-2: motor milestones in infancy.
• HFMSE and RULM: sitting and ambulant SMA patients, and upper limb function.
• NSAA and PUL: ambulant Duchenne patients, and upper limb function.
• Six-minute walk test and timed tests (rise from floor, 10-metre walk-run, stair climbing).
• MFM: general motor function across a wide age and ability range. Brooke and Vignos: functional staging.
• Respiratory: FVC, MIP/MEP, peak cough flow.

Genetic counselling and transition

Genetic counselling should be offered as soon as the diagnosis is made: mode of inheritance, recurrence risk, carrier testing, prenatal and preimplantation options, and risk to other family members. In X-linked conditions the status of mothers and sisters matters, and in autosomal recessive conditions wider family screening is important where there is consanguinity.

As treatments change the natural history, most patients diagnosed in childhood now reach adulthood. Transition is a planned process: it is raised in early adolescence, the patient is informed to the point of being able to describe their own diagnosis and risks, a case summary and surveillance data are assembled before transfer, and a joint consultation is held with the receiving team.