Case Presentation: An 88-year-old female was admitted to the hospital with a complaint of slurred speech and difficulty swallowing of one week duration. On admission, her vitals were stable. Physical examination was unremarkable aside from an NIH stroke scale score of 1 due to dysarthria. Laboratory evaluation was unremarkable. Head CT and brain MRI were negative for signs of a large stroke or bleed. The admitting diagnosis was transient ischemic attack or cerebrovascular accident. On day 2 of hospitalization, the patient had persistent dysarthria and reported dysphagia to solids and liquids that worsened throughout the day. Gastroenterology was consulted and excluded upper GI pathology as the source of symptoms via an EGD. This prompted autoantibody profile testing for neuromuscular junction disease and empiric initiation of Pyridostigmine 30 mg TID. The patient had dramatic symptomatic improvement following oral administration of Pyridostigmine. Autoantibody profile testing revealed positive Ach blocking Ab, AChR binding Ab, and AChR modulating Ab. The patient tested negative for anti-MuSK-MG Ab. A clinical diagnosis of bulbar myasthenia gravis was made. The Pyridostigmine dose was subsequently increased to 60 mg TID to optimize treatment. One month after discharge, the patient reported no recurrence of dysarthria with adherence to the treatment regimen.
Discussion: Myasthenia Gravis (MG) is an autoimmune disorder defined as impaired neuromuscular transmission due to autoantibodies against the acetylcholine receptor (AChR) or muscle specific kinase (MuSK) in the neuromuscular junction.[1] Here, we present a rare case of isolated bulbar MG that is notable for three predominant considerations. The first is its presentation as fatiguable and isolated bulbar weakness in an elderly female. Normally, MG commonly follows a bimodal age of distribution, with the majority of presentations being in younger females or older males.[2] In most patients, dysarthria, dysphagia, and dysphonia emerge only as part of advanced generalized MG rather than as isolated initial symptoms. The second aspect is that this patient was found to have triple antibody positivity for anti-AChR antibodies, despite bulbar MG commonly being associated with anti-MuSK antibodies. While triple antibody positivity is most specific for the diagnosis of MG, a majority of patients will be positive for the binding antibody only, or have a low titer of binding and/or modulating antibodies.[3-4] Strong positivity across all three assays is unusual.[3-4] The final aspect contributing to the peculiarity of this case is treatment efficacy following administration of pyridostigmine. This is significant due to a discrepancy in treatment between serotypes as research suggests anticholinesterase inhibitors are insufficient for treatment of typical bulbar MG, but is effective for anti-AChR MG.[5]
Conclusions: This case emphasizes the importance of considering MG in elderly patients presenting with isolated bulbar symptoms, even in the absence of ocular or limb weakness. Recognition of fatiguability during examination is a critical diagnostic skill that can distinguish MG from other etiologies. Early antibody testing and empiric initiation of pyridostigmine can confirm the diagnosis and prevent unnecessary procedures, aspiration, and morbidity. By expanding the differential to include MG in atypical late-onset presentations, we can reduce diagnostic delays, improve outcomes, and avoid life-threatening complications.