Case report of a patient with Miastenia Gravis associated with amyotrophic lateral sclerosis

Case Presentation: A 45-year-old male patient began experiencing symptoms in February 2023. Initially, he reported muscle weakness and atrophy in the hands, associated with cramps, with lower limbs involvement appearing approximately two months after symptom onset. The condition progressed with thenar and hypothenar muscle atrophy in the hands and significant asymmetric atrophy in the upper limbs. Following the diagnosis of amyotrophic lateral sclerosis (ALS) and initiation of riluzole treatment, the patient developed dysphagia accompanied by ptosis, with a positive ice pack test. Cerebrospinal fluid analysis, ganglioside antibodies, and light chain levels were normal. High levels of acetylcholine receptor antibodies, positive decremental response, and improvement with immunoglobulin and prednisone. Good response with pyridostigmine, based on the clinical and neurophysiological findings. A diagnostic hypothesis of Myasthenia Gravis associated with Amyotrophic Lateral Sclerosis (ALS) was proposed. Discussion: The relevance of this case lies in the rare and complex association between Myasthenia Gravis (MG) and Amyotrophic Lateral Sclerosis (ALS), two distinct neurological conditions with overlapping symptoms, which complicates diagnosis and management. MG is a chronic autoimmune disorder characterized by fluctuating muscle weakness and fatigue. At the same time, ALS is a progressive and fatal neurodegenerative disease affecting motor neurons, leading to muscle weakness and atrophy. The overlap typically manifests in the bulbar region (dysarthria, dysphagia) and ocular region (ptosis, diplopia). Diagnosis is based on clinical evaluation, electromyography (EMG), repetitive nerve stimulation (RNS) tests, and serological assays. Prognosis varies depending on the sequence of disease onset and the extent of neurological involvement. Immunomodulatory therapy may improve MG symptoms and prevent disability. This case underscores the importance of heightened awareness among healthcare professionals to enable early and accurate diagnosis, supported by comprehensive assessment and careful interpretation of test results. Final comments: Although rare, Myasthenia Gravis in association with motor neuron disease - Amyotrophic Lateral Sclerosis (ALS). Treatment may include immunosuppressive drugs for MG, or can be non-invasive, like speech therapy, for ALS, to help with the prognosis of the condition. The diagnosis can be facilitated by antibody serology, Anti-ACh and MuSK-Ab, and neurological physical examination with a well-written anamnesis. Finally, this case report is important to highlight the clinical relevance of recognizing overlapping syndromes and contributes to meaningful discussion in the neuromuscular field.