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Rob Gonsalves Division of Endocrinology, Phoenix Children’s Hospital, Phoenix, Arizona, USA

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Kirk Aleck Division of Genetics, Phoenix Children’s Hospital, Phoenix, Arizona, USA

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Dorothee Newbern Division of Endocrinology, Phoenix Children’s Hospital, Phoenix, Arizona, USA

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Gabriel Shaibi Division of Endocrinology, Phoenix Children’s Hospital, Phoenix, Arizona, USA

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Chirag Kapadia Division of Endocrinology, Phoenix Children’s Hospital, Phoenix, Arizona, USA

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Oliver Oatman Division of Endocrinology, Phoenix Children’s Hospital, Phoenix, Arizona, USA

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Summary

Single-minded homolog 1 (SIM1) is a transcription factor that plays a role in the development of both the hypothalamus and pituitary. SIM1 gene mutations are known to cause obesity in humans, and chromosomal deletions encompassing SIM1 and other genes necessary for pituitary development can cause a Prader–Willi-like syndrome with obesity and hypopituitarism. There have been no reported cases of hypopituitarism linked to a single SIM1 mutation. A 21-month-old male presented to endocrinology clinic with excessive weight gain and severe obesity. History was also notable for excessive drinking and urination. Endocrine workup revealed central hypothyroidism, partial diabetes insipidus, and central adrenal insufficiency. Genetic evaluation revealed a novel mutation in the SIM1 gene. No other genetic abnormalities to account for his obesity and hypopituitarism were identified. While we cannot definitively state this mutation is pathogenic, it is notable that SIM1 plays a role in the development of all three of the patient’s affected hormone axes. He is now 6 years old and remains on treatment for his pituitary hormone deficiencies and continues to exhibit excessive weight gain despite lifestyle interventions.

Learning points:

  • Mutations in SIM1 are a well-recognized cause of monogenic human obesity, and there have been case reports of Prader–Willi-like syndrome and hypopituitarism in patients with chromosomal deletions that contain the SIM1 gene.

  • SIM1 is expressed during the development of the hypothalamus, specifically in neuroendocrine lineages that give rise to the hormones oxytocin, arginine vasopressin, thyrotropin-releasing hormone, corticotropin-releasing hormone, and somatostatin.

  • Pituitary testing should be considered in patients with severe obesity and a known genetic abnormality affecting the SIM1 gene, particularly in the pediatric population.

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Jai Madhok Department of Anesthesiology, Perioperative and Pain Medicine

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Amy Kloosterboer Department of Anesthesiology, Perioperative and Pain Medicine

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Chitra Venkatasubramanian Department of Neurology & Neurological Sciences, Stanford University Medical Center, Stanford, California, USA

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Frederick G Mihm Department of Anesthesiology, Perioperative and Pain Medicine

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Summary

We report the case of a 76-year-old male with a remote history of papillary thyroid cancer who developed severe paroxysmal headaches in the setting of episodic hypertension. Brain imaging revealed multiple lesions, initially of inconclusive etiology, but suspicious for metastatic foci. A search for the primary malignancy revealed an adrenal tumor, and biochemical testing confirmed the diagnosis of a norepinephrine-secreting pheochromocytoma. Serial imaging demonstrated multiple cerebral infarctions of varying ages, evidence of vessel narrowing and irregularities in the anterior and posterior circulations, and hypoperfusion in watershed areas. An exhaustive work-up for other etiologies of stroke including thromboembolic causes or vasculitis was unremarkable. There was resolution of symptoms, absence of new infarctions, and improvement in vessel caliber after adequate alpha-adrenergic receptor blockade for the management of pheochromocytoma. This clinicoradiologic constellation of findings suggested that the etiology of the multiple infarctions was reversible cerebral vasoconstriction syndrome (RCVS). Pheochromocytoma remains a poorly recognized cause of RCVS. Unexplained multifocal cerebral infarctions in the setting of severe hypertension should prompt the consideration of a vasoactive tumor as the driver of cerebrovascular dysfunction. A missed or delayed diagnosis has the potential for serious neurologic morbidity for an otherwise treatable condition.

Learning points:

  • The constellation of multifocal watershed cerebral infarctions of uncertain etiology in a patient with malignant hypertension should trigger the consideration of undiagnosed catecholamine secreting tumors, such as pheochromocytomas and paragangliomas.

  • Reversible cerebral vasoconstriction syndrome is a serious but reversible cerebrovascular manifestation of pheochromocytomas that may lead to strokes (ischemic and hemorrhagic), seizures, and cerebral edema.

  • Alpha-adrenergic receptor blockade can reverse cerebral vasoconstriction and prevent further cerebral ischemia and infarctions.

  • Early diagnosis of catecholamine secreting tumors has the potential for reducing neurologic morbidity and mortality in patients presenting with cerebrovascular complications.

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Tzy Harn Chua Department of Endocrinology, Changi General Hospital, Singapore

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Wann Jia Loh Department of Endocrinology, Changi General Hospital, Singapore

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Summary

Severe hyponatremia and osmotic demyelination syndrome (ODS) are opposite ends of a spectrum of emergency disorders related to sodium concentrations. Management of severe hyponatremia is challenging because of the difficulty in balancing the risk of overcorrection leading to ODS as well as under-correction causing cerebral oedema, particularly in a patient with chronic hypocortisolism and hypothyroidism. We report a case of a patient with Noonan syndrome and untreated anterior hypopituitarism who presented with symptomatic hyponatremia and developed transient ODS.

Learning points:

  • Patients with severe anterior hypopituitarism with severe hyponatremia are susceptible to the rapid rise of sodium level with a small amount of fluid and hydrocortisone.

  • These patients with chronic anterior hypopituitarism are at high risk of developing ODS and therefore, care should be taken to avoid a rise of more than 4–6 mmol/L per day.

  • Early recognition and rescue desmopressin and i.v. dextrose 5% fluids to reduce serum sodium concentration may be helpful in treating acute ODS.

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