What are the symptoms of Myasthenia Gravis (MG)?

Symptoms of Myasthenia Gravis

Myasthenia gravis causes fluctuating muscle weakness that worsens with activity and improves with rest, most commonly presenting with drooping eyelids (ptosis) and double vision (diplopia), which can progress to involve facial, swallowing, speech, limb, and potentially life-threatening respiratory muscles. 1, 2

Ocular Symptoms (Most Common Initial Presentation)

• Ptosis (drooping eyelids) is often the first symptom, appearing in 50% of patients as the initial manifestation, and may affect one or both eyes 1, 2, 3
• Diplopia (double vision) results from weakness of the extraocular muscles that control eye movement 1, 2
• Variable strabismus (misalignment of the eyes) is characteristic and changes during examination 2, 3
• Slow ocular saccades (rapid eye movements) occur due to extraocular muscle fatigue 2, 3
• Extraocular muscles are particularly vulnerable because they have twitch fiber composition and fewer acetylcholine receptors 1, 3

Bulbar Symptoms (Speech and Swallowing)

• Dysarthria (slurred speech) develops as facial and throat muscles weaken 1, 2
• Dysphagia (difficulty swallowing) affects many patients and can lead to choking or aspiration 4, 1
• Facial muscle weakness causes reduced facial expressions and drooling 1, 3
• Difficulty chewing food occurs with prolonged eating 3

Limb and Trunk Symptoms

• Proximal muscle weakness (shoulders, hips) is more prominent than distal muscle weakness (hands, feet) 1, 2
• Difficulty climbing stairs or rising from a seated position reflects proximal leg weakness 4
• Difficulty holding up the head occurs with neck muscle weakness 1, 3
• Weakness is typically bilateral but can be asymmetrical 1, 2
• Trunk muscle involvement affects posture and stability 1

Respiratory Symptoms (Most Serious Manifestation)

• Respiratory muscle weakness represents the most life-threatening complication, potentially progressing to respiratory insufficiency or failure (myasthenic crisis) 4, 1, 2
• Dyspnea (shortness of breath) worsens with exertion 4
• Hoarseness may indicate involvement of respiratory and laryngeal muscles 4

Hallmark Clinical Characteristics

• Fluctuating weakness is the defining feature—symptoms worsen with continued muscle use and improve with rest 1, 2, 3
• Fatiguability causes symptoms to worsen as the day progresses or with repetitive activity 1, 2, 3
• Variable presentation during examination is typical, with weakness patterns changing throughout the evaluation 2, 3
• Temporary improvement with rest or ice pack application (ice pack test) is characteristic 1, 3

Disease Progression Pattern

• 50% of patients initially present with only ocular symptoms (classified as MGFA Class I) 1, 2, 3
• 50-80% of those with initial ocular symptoms will develop generalized myasthenia gravis within the first few years 1, 2, 3
• Progression typically follows: ocular → bulbar → limb → respiratory muscle involvement 1

Critical Warning Signs Requiring Immediate Attention

• Any dysphagia, facial weakness, or respiratory muscle weakness warrants urgent evaluation, as these indicate Grade 3-4 disease with potential for rapid deterioration 4
• Rapidly progressive symptoms require immediate hospitalization and possible ICU-level monitoring 4
• Avoid medications that worsen myasthenia: beta-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolide antibiotics 4, 1, 2