(603) A Case Report on Posterior Reversible Encephalopathy Syndrome Secondary to Thyrotoxicosis

Introduction: Hyperthyroidism is a common clinical entity characterized by variable presentations. We describe a case of Posterior Reversible Encephalopathy Syndrome (PRES) as a rare presentation of hyperthyroidism in a critically ill patient.

Description: A 40 year old female with no significant past medical history presented to the emergency department with a 2 week history of increased drowsiness and visual impairments worsening for the past 2 months. On initial presentation, the patient was found to have a blood pressure of 300/192 mmHg with bilateral exophthalmos, decreased peripheral and central vision bilaterally and bilateral papilledema on fundoscopic exam. Laboratory findings included an elevated Free T4 (1.9 ng/dL), Total T3 (>500 ng/dL), Free T3 (7.7 pg/mL) with normal TSH (1.15 ng/dL). Brain MRI without contrast resulted in hyperintense signal on T2 in the parietal and occipital lobes with vasogenic edema and bilateral bulging of the optic nerve discs consistent with PRES. Patient was treated in the intensive care unit with nicardipine drip with the initial systolic blood pressure goal of 200-220 mmHg. Patient was started on propranolol, methimazole and lisinopril for control of blood pressure and thyrotoxicosis. Secondary causes of hypertension were ruled out, urine and plasma metanephrines were normal as well as renal ultrasound. Visual deficits improved with control of blood pressure. Diagnositic lumbar puncture revealed an opening pressure >530 mm H20 (53 cm H20) and was negative for pathogens. Further work-up revealed elevated thyroid peroxidase antibodies (163.1 IU/mL) and thyroid stimulating immunoglobulin (2.36 IU/L).

Discussion: PRES is a rare clinical and radiological syndrome characterized by brain edema. Delayed identification and inadequate management can lead to life-threatening complications, such as status epilepticus or coma. In this case, identification of thyrotoxicosis secondary to Graves’ disease and prompt initiation of therapy was paramount in the management of this case. This case report increases awareness of its co-existence with thyrotoxicosis and adds to the incidence of this rare syndrome.