(6.03) Thyroid Storm Presenting as Fever in a Critically ill Patient Admitted with Myasthenic Crisis: An autoimmune overlap

Introduction : Thyroid storm is a rarely encountered endocrine emergency manifesting in less than 10% of patients admitted with thyrotoxicosis. Thyroid storm is a potentially life-threatening condition with mortality rates approaching 10% likely due to multiple organ dysfunction. Fever is a common symptom noted in thyroid storm, however fever as the sole evidene of thyroid crises is extremely rare. Myasthenia Gravis (MG) and hyperthyroidism can often co exist in the same patient as a result of auto-immune overlap. Both MG and hyperthyroidism share similar clinical features and recognizing thyroid stormin a patient with Myasthenic crisis can be a diagnostic challenge. We present the case of a 50 year old male admitted to the hospital for Myasthenic Crises with hospital coarse complicated by thyroid storm presenting as fever.

Case(s) Description : We present a 50-year-old male who was recently diagnosed with Grace's Disease (TSH< 0.01, free T4 3.2, positive TSI) and Myasthenia Gravis ( postive Anti-acetylcholine antibodies) who was brought to the emergency department with progressive proximal limb and bulbar weakness. Due to increasing confusion, he was intubated. The patient was started on a course of IVIG for five days along, with methyl prednisone for three days and pyridostigmine. For his Grave's disease, he remained on methimazole 5mg. Despite completion of therapy the patient was failing extubation trials. The patient was becomming more agitated, was spiking high-grade fever, and remained tachycardic with Heart Rate in the 110s-140s despite a negative infectioys work up. An echocardiogram revealed heart failure with Ejection Fraction of 20-25%. In the setting of unrelenting fever, cardiomyopathy and acute encephalopathy the patient was diagnosed with thyroid storm meeting Burch Wartosfky criteria with score >45. The patient was treated with solucortef 100mg every 8 hours and methimazole swithed to PTU. The patient's fever broke and agitation improved and he was ultimately extubated.

Discussion : Myasthenia Gravis and Hyperthyroidism Grave's disease can co-exist in the same patient. Having similar clinical characteristics can make diagnosis of a flare up of either disease challenging. Our patient was initially treated for a Myasthenia Crises however once he was diagnosed and treated for thyroid storm his clinical condition rapidly improved. Our case highlights that clinicians should always have a low threshold for considering thyroid storm in a critically ill patient who has Grave's disease even if the initial presentation is consistent with a separate auto immune disease. Hyperthyroidism in Grave's disease and Myasthenia Gravis can have a paradoxical relationship and treating one illness may make the other worse. It is imperative to perform a proper clinical examination and thorough investigation to diagnose both conditions and to treat a storm and crisis at the same time.