🧠 Neuromuscular Diseases 

Lesson Objectives

By the end of this lesson, learners should be able to:

1. Define common paediatric neuromuscular disorders.

2. Recognize clinical features and variants of Guillain-Barré Syndrome, Myasthenia Gravis, and Duchenne Muscular Dystrophy.

3. Identify investigations required for diagnosis.

4. Apply appropriate supportive and pharmacological management.

5. Know referral criteria for specialist care.

Guillain-Barré Syndrome (GBS)

Description:
GBS is an autoimmune polyradiculopathy, often triggered by infection. It is a notifiable disease and the most common acquired polyneuropathy in children. Main variants in children include:

• Acute Inflammatory Demyelinating Polyradiculoneuropathy (AIDP) – 80–90%

• Acute Motor Axonal Neuropathy (AMAN)

• Miller-Fisher variant

Clinical Features:

• Symmetrical, ascending motor weakness

• Areflexia (absent tendon reflexes)

• Distal sensory alteration

• Pain or paraesthesia

• External ophthalmoplegia, sensory ataxia, weakness with areflexia (Miller-Fisher variant)

• Rapid progression may involve trunk, neck, arms, face, and cranial nerves; may cause respiratory failure or autonomic dysfunction

Investigations:

• Acute flaccid paralysis workup

• Stool samples (2, 24–48 hrs apart) to exclude polio

• Lumbar puncture: CSF shows elevated protein with few cells (albuminocytologic dissociation); glucose normal

Treatment:

Supportive:

• Notify as AFP, admit to PICU if available

• Monitor respiratory and autonomic function; provide ventilation support if rapidly progressing

• Adequate nutrition and fluid replacement

• Pain management (up to 90% of children experience pain)

Pharmacological (specialist supervision):

• IV Immunoglobulin: 1 g/kg/day over 12–16 hrs for 2 consecutive days or 0.4 g/kg/day for 5 days

Myasthenia Gravis (MG)

Description:
Autoimmune disorder causing muscle fatigue. Mild cases affect ocular muscles (ptosis, ophthalmoplegia), severe cases involve proximal muscles, respiratory, and bulbar control.

Clinical Features:

• Muscle fatigue worsening with exercise

• Ptosis or ophthalmoplegia

• Myasthenic crisis: inability to breathe or swallow, may be precipitated by systemic infection

Investigations:

• CT chest to rule out thymoma

Treatment:

• Pyridostigmine 1–5 mg/kg/day orally in 4–6 divided doses

• Prednisolone 1 mg/kg/day orally (max 60 mg)

• Myasthenic crisis: IV Immunoglobulin (same dosing as GBS) under specialist care

Referral: All patients must be referred to higher-level facilities for specialized management

Duchenne Muscular Dystrophy (DMD)

Description:
X-linked recessive disorder causing progressive muscle weakness in boys; carrier females may show mild weakness. Caused by mutations in the dystrophin gene. Family history often present.

Clinical Features:

• Delayed walking, toe walking

• Gowers sign

• Waddling gait, lumbar lordosis

• Calf pseudohypertrophy

• Short stature

• Progressive proximal muscle weakness (wheelchair-bound by ~13 years)

• Cardiomyopathy

• Mild cognitive impairment or behavioral issues

Investigations:

• Markedly elevated creatine kinase (CK)

• AST/ALT may also be elevated

Treatment:

Supportive:

• Pain management

• Physiotherapy and occupational therapy

• Nutritional and psychosocial support

Pharmacological:

• Oral corticosteroids (prednisone 0.75 mg/kg daily, max 30–40 mg) after plateau/decline in motor function, in consultation with a neurologist

Referral: All cases require specialist assessment