A Case of Gestational Thyrotoxicosis Associated with Wernicke's Encephalopathy

To present a case of gestational thyrotoxicosis and hyperemesis gravidarum associated with Wernicke's encephalopathy.

We present a detailed case report with the clinical, imaging, and laboratory findings of the patient and review the pertinent literature.

A 36-year-old woman at 14 weeks of gestation was admitted to the hospital for management of severe hyperemesis gravidarum (HG). While hospitalized, she developed low-grade fever, tachycardia, hypotension, and altered mentation. Laboratory tests were diagnostic of hyperthyroidism. Physical examination revealed a confused, lethargic woman with a normal-size thyroid and pendular nystagmus in primary and lateral gaze. She was treated empirically for thyroid storm with methimazole and other measures. A brain magnetic resonance imaging (MRI) study done later showed hyperintense abnormal signals in bilateral thalamic regions, consistent with Wernicke's encephalopathy (WE). She was immediately started on intravenous thiamine and her mental status improved considerably within 3 to 4 days. Within 2 weeks, the patient's thyroid-function tests normalized and methimazole was discontinued. A repeat brain MRI 6 months later showed marked reduction of signal intensity in both thalamic regions.

This case demonstrates that gestational thyrotoxicosis in a patient with HG can precipitate acute WE, which may mimic thyroid storm and thus delay appropriate management of this neurologic disorder. We conclude that prophylactic thiamine administration may be considered before caloric replacement in patients who present with HG and acute neurologic dysfunction.