Background and Clinical Significance: Osmotic demyelination syndrome (ODS) and pituitary apoplexy are rare but potentially severe neurological and endocrine complications that can arise in the context of profound metabolic stress. Case Presentation: We describe the case of a previously healthy 34-year-old man who developed severe symptomatic hyponatremia shortly after receiving his second dose of an mRNA COVID-19 vaccine. Initial laboratory findings and clinical assessment were consistent with syndrome of inappropriate antidiuretic hormone secretion. Following correction of serum sodium, the patient experienced neurological deterioration with gait disturbance, dysarthria, and cognitive impairment. Follow-up brain MRI demonstrated extrapontine osmotic demyelination involving the basal ganglia and thalamus, despite initially normal imaging. During subsequent endocrinological follow-up, pituitary MRI revealed pituitary apoplexy in a previously unrecognized adenoma, accompanied by evolving partial hypopituitarism. The patient was managed with careful electrolyte control and long-term hormone replacement therapy, including hydrocortisone, levothyroxine, and recombinant growth hormone, resulting in gradual functional and cognitive improvement. Conclusions: This case highlights the interaction between severe hyponatremia, osmotic stress, and pituitary vulnerability, and emphasizes the need for cautious sodium correction, careful interpretation of temporal associations, and continued clinical vigilance in the context of COVID-19 vaccination programs.

Cushing disease (CD) secondary to adrenocorticotropin (ACTH)-secreting pituitary macroadenomas is uncommon, accounting for 10% to 15% of cases. We describe 3 patients from South Africa who presented with overt clinical features of hypercortisolism and considerable systemic complications, including hypertension, diabetes mellitus, and osteoporosis. Biochemical testing confirmed ACTH-dependent hypercortisolism with hypopituitarism and mild hyperprolactinemia consistent with stalk effect. Magnetic resonance imaging demonstrated pituitary macroadenomas, measuring 10 mm or greater, with parasellar extension. Mass effect was observed in 1 patient resulting in cranial nerve III palsy, while the others had visual field deficits secondary to optic chiasm compression. All patients underwent endoscopic transsphenoidal surgery, with 1 achieving remission and 2 developing recurrence. These cases highlight that ACTH-secreting macroadenomas can present with severe systemic disease and significant mass effect, and emphasize the importance of lifelong follow-up.

Traumatic brain injury (TBI) is a common injury that can lead to significant and prolonged morbidity. Growing evidence suggests hypopituitarism is prevalent after TBI and if left untreated, contributes to high symptom burden, limited rehabilitation participation, and poor functional recovery. The neurorehabilitation specialist is uniquely situated to identify patients at risk of hypopituitarism during all phases of recovery. There is significant overlap in symptom presentation between hypopituitarism and primary symptoms of TBI. Fatigue, disrupted sleep, altered cognition, weakness, exercise intolerance, and declining mental health can occur due to the brain injury or hypopituitarism, making clinical diagnosis challenging. Collaboration with endocrinologists can aid in organizing timely and appropriate workup, diagnosis, and initiation of hormone replacement therapy. Understanding the clinical features, timing, and trajectory of hypopituitarism after TBI allows neurorehabilitation specialists to facilitate diagnosis and treatment of hypopituitarism which may enhance rehabilitation engagement, improve symptom burden, and ultimately optimize recovery.

Rathke's cleft cyst (RCC) is a benign pituitary lesion that is often asymptomatic but can cause hypopituitarism, including central adrenal insufficiency, which may become clinically apparent under physiological stress. However, RCC presenting with adrenal insufficiency unmasked by acute respiratory illness is rare, particularly in elderly patients. We report a case of RCC diagnosed after adrenal insufficiency became evident following pneumonia-associated asthma exacerbation. An 89-year-old woman presented with fever, productive cough, and generalized fatigue and was diagnosed with pneumonia-triggered asthma exacerbation. Initial laboratory evaluation revealed hyponatremia (serum sodium 126 mEq/L). She was treated with bronchodilators, systemic corticosteroids, and antibiotics, resulting in prompt improvement of respiratory symptoms and normalization of serum sodium levels. After discontinuation of corticosteroids and discharge, she developed persistent fatigue, anorexia, and right eyelid ptosis. Brain magnetic resonance imaging revealed a 22-mm cystic lesion in the pituitary gland consistent with RCC. Endocrine evaluation demonstrated markedly reduced adrenocorticotropic hormone and cortisol levels, along with central hypothyroidism, hypogonadism, and growth hormone deficiency, confirming panhypopituitarism with central adrenal insufficiency. Hydrocortisone replacement therapy was initiated, leading to clinical stabilization. Surgical intervention was deferred due to advanced age and absence of visual field defects, and the patient was managed conservatively with hormone replacement and follow-up imaging. This case highlights that acute respiratory illness may precipitate overt adrenal insufficiency in patients with previously unrecognized RCC. Transient improvement with corticosteroids during acute treatment may mask the underlying endocrine disorder, delaying diagnosis. Persistent fatigue, hyponatremia, or neurological findings after resolution of respiratory illness should prompt evaluation for central adrenal insufficiency and pituitary pathology, as early recognition and hormone replacement are essential to prevent life-threatening complications.