To investigate the diagnostic challenges of congenital myasthenic syndromes (CMS) in adult neuromuscular practice. We searched the Mayo Clinic database for patients with CMS diagnosed in adulthood in Show more
To investigate the diagnostic challenges of congenital myasthenic syndromes (CMS) in adult neuromuscular practice. We searched the Mayo Clinic database for patients with CMS diagnosed in adulthood in the neuromuscular clinic between 2000 and 2016. Clinical, laboratory, and electrodiagnostic data were reviewed. We identified 34 patients with CMS, 30 of whom had a molecular diagnosis (14 Misdiagnosis occurred in 94% of the adult patients with CMS and causes a median diagnostic delay of nearly 3 decades from symptom onset. Seronegative myasthenia gravis and muscle diseases were the 2 most common misdiagnoses, which led to treatment delay and unnecessary exposure to immunotherapy, thymectomy, or muscle biopsy. Show less