Myasthenia gravis and neuromuscular junction disorders: Case

Clinical case of a 14-year-old girl with autoimmune myasthenia gravis, covering the fluctuating fatigable ocular and bulbar weakness with preserved reflexes and pupils and a positive ice pack test, the falling forced vital capacity and bulbar weakness triggering intensive care, the antibody panel and repetitive nerve stimulation, pyridostigmine dosing, the low-start corticosteroid with early steroid-sparing, intravenous immunoglobulin 2 g per kg over two to five days for the threatened crisis, the exclusion of a thymoma and the thymectomy decision, and the paediatric prognosis and transition plan.

Prompt

A previously well 14-year-old girl presents over three weeks with worsening drooping of her eyelids by the afternoon, double vision, a nasal voice that tires as she reads aloud, and difficulty finishing a meal. Examination shows fatigable bilateral ptosis on sustained upgaze, variable ophthalmoparesis, a weak cough, and proximal arm weakness that droops within one minute of sustained upward posture. The deep tendon reflexes and the pupils are normal, and sensation is intact. Her weight is 52 kilograms. Her bedside forced vital capacity is 17 mL per kilogram, down from 24 mL per kilogram four hours ago. An ice pack over the right eyelid for two minutes lifts the ptosis.

Summary and immediate impression

This girl presents a textbook case of autoimmune myasthenia gravis with a threatened crisis. The tempo is subacute over weeks, with fluctuating, fatigable weakness of the ocular, bulbar, and proximal muscles that worsens through the day and recovers with rest, preserved reflexes and pupils, and a positive ice pack test. The falling forced vital capacity and the bulbar weakness are the immediate threats, and they drive the decision to escalate to intensive care. The diagnosis is supported by the clinical picture and confirmed by the antibody panel and neurophysiology, and the symptomatic treatment is pyridostigmine with disease-modifying immunotherapy. ^[1]

References5Show

[1]Gilhus NE Myasthenia Gravis. N Engl J Med, 2016.PMID 28029925
[2]Narayanaswami P, Sanders DB, Wolfe G, et al International Consensus Guidance for Management of Myasthenia Gravis: 2020 Update. Neurology, 2021.PMID 33144515
[5]Gajdos P, Chevret S, Toyka KV Intravenous immunoglobulin for myasthenia gravis. Cochrane Database Syst Rev, 2012.PMID 23235588
[7]Alshekhlee A, Miles JD, Katirji B, et al Incidence and mortality rates of myasthenia gravis and myasthenic crisis in US hospitals. Neurology, 2009.PMID 19414721
[11]Guptill JT, Sanders DB Update on muscle-specific tyrosine kinase antibody positive myasthenia gravis. Curr Opin Neurol, 2010.PMID 20613516

Myasthenia gravis and neuromuscular junction disorders: Case

Summary and immediate impression

References5Show

[1]Gilhus NE Myasthenia Gravis. N Engl J Med, 2016.PMID 28029925
[2]Narayanaswami P, Sanders DB, Wolfe G, et al International Consensus Guidance for Management of Myasthenia Gravis: 2020 Update. Neurology, 2021.PMID 33144515
[5]Gajdos P, Chevret S, Toyka KV Intravenous immunoglobulin for myasthenia gravis. Cochrane Database Syst Rev, 2012.PMID 23235588
[7]Alshekhlee A, Miles JD, Katirji B, et al Incidence and mortality rates of myasthenia gravis and myasthenic crisis in US hospitals. Neurology, 2009.PMID 19414721
[11]Guptill JT, Sanders DB Update on muscle-specific tyrosine kinase antibody positive myasthenia gravis. Curr Opin Neurol, 2010.PMID 20613516