Autoimmune Myasthenia Gravis: Diagnosis and Management in a Young Patient Seen for Consultation at the National Reference General Hospital of N’Djamena (Chad)

Introduction: Myasthenia gravis is a neuromuscular junction disorder characterized by fatigability, muscle weakness affecting the oculomotor, bulbar, and skeletal muscles, worsening with exertion and resolving at rest. It is an autoimmune neurological disease that can be life-threatening due to respiratory muscle damage. Clinical Case: This is a 20-year-old male XL patient with no particular history who presents with muscle fatigue during exercise associated with bilateral ptosis, predominantly on the right. These symptoms have been evolving for 2 months. The neurological examination found a myasthenic score of 85/100 with bilateral ptosis and tetraparesis. The ENMG, looking for a decrement by repetitive stimulation at 3 c/s, revealed a significant decrement of 5% in the proximal muscles (facial-orbital nerve pair) and distal muscles (median nerve-breast adductor pollicis). The electrophysiological examination (ENMG), key to the diagnosis of myasthenia gravis, was carried out on our patient, objectifying a decrement. Discussion: In our series, our patient is 20 years old. The literature informs us that myasthenia gravis begins at any age, from 6 months to over 80 years, but mainly affects adults under 40 years, the majority of whom are women. The normality of the ENMG should not exclude the diagnosis of myasthenia gravis. In the study of our patient, the ENMG showed a decrease. Indeed, the dosage of anti-RAch and anti-MUSK antibodies was carried out abroad without showing any particularities. The negativity of anti-RAch antibodies often leads to the search for anti-MUSK antibodies. The treatment consists of anti-cholinergics, namely pyridostigmine bromide (Mestinon 60 mg), with a gradual increase in doses depending on the case to reach a minimum effective dose in order to avoid muscarinic side effects. Indeed, anticholinergics are the first-line treatment for myasthenia gravis, increasing the amount of acetylcholine at the motor endplate and its effectiveness in all forms of myasthenia gravis. Given the persistence of muscle fatigue during exercise, a course of corticosteroid therapy was used, initially as a bolus for 5 days at a dose of 250 mg in 250 mL of isotonic serum to be administered over 30 minutes in association with adjuvant treatment (albendazole 400 mg as a single dose, calcium and potassium supplementation, and omeprazole 20 mg), followed by oral corticosteroid therapy at 0.5 or 1 mg/kg. Treatment with an immunosuppressant (azathioprine) was proposed, given the persistence of clinical signs. Conclusion: Myasthenia gravis, which is the most common autoimmune disease of the neuromuscular junction. It is rare in Sub-Saharan Africa in the literature; it should not be overlooked because of the life-threatening risk caused by damage to the respiratory and swallowing muscles, resulting in an impact on daily life with muscular fatigue during exercise.