Coexistence of anti-musk-positive bulbar myasthenia gravis and myotonic dystrophy Type 1: the first case report from Türkiye

Abstract

Muscle-specific tyrosine kinase (MuSK) myasthenia gravis (MG) is an acute-onset subtype of MG that primarily affects the fasciobulbar muscles and begins with progressive velopharyngeal and respiratory symptoms such as early respiratory crises, swallowing, and speaking difficulties. Myotonic dystrophy Type 1 (DM1) is an autosomal dominantly inherited autoimmune neuromuscular disease characterized by distal-dominant muscle weakness, cardiovascular pathologies, and corneal disorders. In this case report, we discussed a 42-year-old female patient with a previous diagnosis of DM1 and diagnosed with MuSK-MG as a result of electroneuromyographic and antibody tests upon the development of bulbar symptoms and thymus hyperplasia. The patient underwent video-assisted thymectomy, and medical treatment was started with a combination of pyridostigmine and methylprednisolone. The coexistence of anti- MuSK positive MG with thymoid hyperplasia and DM 1 has not been reported so far, and it has been predicted that both diseases may trigger each other through neuroinflammatory mechanisms on an autoimmunergic basis.

Keywords

• Autoimmunity
• muscle-specific tyrosine kinase myasthenia gravis
• myotonic dystrophy Type 1
• neuroinflammation
• thymus hyperplasia

Anti-musk pozitif bulbar myastenia gravis ve miyotonik distrofi Tip 1 birlikteliği: Türkiye'den ilk vaka sunumu

Öz

Kas spesifik tirozin kinaz (MuSK) miyastenia gravis (MG), öncelikle fasyobulbar kasları etkileyen ve erken solunum krizleri, yutma ve konuşma güçlükleri gibi ilerleyici velofaringeal ve solunum semptomlarıyla başlayan, MG'nin akut başlangıçlı bir alt tipidir. Miyotonik distrofi Tip 1 (DM1), distal dominant kas zayıflığı, kardiyovasküler patolojiler ve kornea bozuklukları ile karakterize, otozomal dominant geçişli, otoimmün nöromüsküler bir hastalıktır. Bu olgu sunumunda, daha önce DM1 tanısı alan, bulber semptomları ve timus hiperplazisi gelişmesi üzerine elektronöromiyografik ve antikor testleri sonucunda MuSK-MG tanısı alan 42 yaşındaki kadın hastayı tartıştık. Hastaya video yardımlı timektomi uygulandı ve piridostigmin ve metilprednizolon kombinasyonu ile medikal tedaviye başlandı. Anti-MuSK pozitif MG ile timoid hiperplazi ve DM 1'in birlikteliği şu ana kadar bildirilmemiş olup, her iki hastalığın otoimmünerjik temelde nöroinflamatuar mekanizmalar yoluyla birbirini tetikleyebileceği öngörülmektedir.

Anahtar Kelimeler

• Otoimmünite
• kas spesifik tirozin kinaz miyastenia gravis
• miyotonik distrofi Tip 1
• nöroinflamasyon
• timus hiperplazisi

Kaynakça

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