(729) Ice Pack Test: A Quick and Easy Tool in Diagnosis of Myasthenia Gravis During Myasthenia Crisis

Introduction: Myasthenia Gravis diagnosis is often delayed pending results of acetylcholine antibody tests or second-line Muscle Specific Kinase (MuSK) antibody test. This delays therapy in MG crisis. Here, we have a case of MG where ice pack test promptly informed clinical decision on commencing MG crisis therapy.

Description: 66-year-old male with 6 months of ptosis, dysphagia, and right palatine tonsillitis with abscess was hospitalized at our tertiary center due to worsening dysphagia and dysphagia. He was first hospitalized for bulbar symptoms 2 months earlier at a community hospital due to throat mass noted on neck CT scan, and required intubation and ICU care. Neurology diagnosed him with eye lids swelling and ptosis from angioedema. On discharge, the diagnosis was noted to be acute dysphagia from right palatine tonsillitis with abscess. Within 3 weeks, he was hospitalized again with bulbar symptoms and bilateral leg weakness. Neck CT scan showed prominent lingual tonsils without abscess. Due to prior complex intubation, he was transferred to our tertiary center. Initial impression of his case was malignancy versus infection, but he became acutely altered and was intubated due to respiratory failure. He was alert within a day. On exam, patient could not open his eyes, and was wearing neck brace for head support. Due to history and unclear etiology for recurrent intubation, MG was suspected. An ice pack test for 5 minutes was positive with patient able to open his eyes. Antibodies for MG were sent and patient started Myasthenia Crisis therapy with 5 plasmaphereses, pyridostigmine and prednisone. By discharge, he was ambulating on all extremities and no fatigability. His EMG showed post-synaptic neuromuscular junction dysfunction consistent with suspected MG, infectious work up was negative, and he was positive for acetylcholine receptor binding antibody, receptor blocking antibody, and receptor modulating antibody.

Discussion: This case elucidates importance of keeping differentials broad. Our patient was diagnosed with MG after his third hospital admission and recurrent intubation. The ice pack test is a simple tool for evaluating myasthenia diplopia. According to studies, it has high specificity of 98.3% with 95% CI (90.3%-99.9%), and sensitivity at 76.9% with 95% CI (49.06% - 92.50%).