Extracranial arteriovenous malformation mimicking a peripheral nerve tumor: illustrative case.

BACKGROUND: Arteriovenous malformations (AVMs) are vascular malformations that are more commonly found intracranially, followed by the head, neck, limbs, and trunk. Extracranially, AVMs can mimic peripheral nerve tumors, leading to misdiagnosis. OBSERVATIONS: A 19-year-old female, who presented with left lateral lower leg pain, was preoperatively thought to have a peripheral nerve tumor; at surgery, however, she was found to have an extracranial AVM. The distinct margins of the tumor on preoperative magnetic resonance imaging suggested that the patient might have a peripheral nerve tumor; however, the clinical symptoms of focal pain at rest and the absence of Tinel's sign should have raised questions about this diagnosis. LESSONS: This case highlights the difficulty in differentiating a peripheral nerve tumor from an extracranial AVM in certain clinical scenarios. It is important to use a multifaceted diagnostic approach to get a correct preoperative diagnosis and plan treatment appropriately.

Postoperative Hyponatremia After Endoscopic Endonasal Resection of Pituitary Adenomas: Historical Complication Rates and Risk Factors.

BACKGROUND: Hyponatremia is a common complication following endoscopic endonasal resection (EER) of pituitary adenomas. We report a single-center, multisurgeon study detailing baseline clinical data, outcomes, and factors associated with postoperative hyponatremia. METHODS: This was a retrospective cohort study of patients undergoing EER for pituitary adenoma at Tufts Medical Center. Most procedures were performed by the senior author (C.B.H.). Cases were included if at least 1 postoperative sodium value was available and pathology confirmed pituitary adenoma. Hyponatremia was defined as a postoperative sodium level <135 mEq/L. RESULTS: A total of 272 patients underwent 310 EER procedures that met the study inclusion criteria. The mean patient age was 53.3 years, and mean tumor size was 18.8 mm. Postoperative hyponatremia occurred in 12.6% of cases, with 3.6% developing hyponatremia prior to discharge. Lower preoperative sodium level was associated with an increased risk of developing any postoperative hyponatremia. Older age, prolactinoma pathology, and use of selective serotonin reuptake inhibitors were associated with moderate to severe hyponatremia (≤129 mEq/L), and lower preoperative sodium was associated with mild hyponatremia (130-134 mEq/L). Hyponatremia-related readmissions within 30 days occurred in 3.9% of patients. Both African-American race and postoperative hyponatremia were associated with an increased risk of 30-day readmission. The mean nadir sodium for hyponatremic patients was 129.9 mEq/L. Growth hormone-secreting pathology was associated with lower postoperative nadir sodium, whereas higher preoperative sodium was associated with higher postoperative nadir sodium. CONCLUSIONS: Hyponatremia is a common postoperative complication of EER for pituitary lesions that can cause significant morbidity, increased readmissions, and increased healthcare costs.