Effect of vasopressin V2-receptor antagonist tolvaptan on syndrome of inappropriate antidiuresis (SIAD) after transsphenoidal pituitary surgery: recovery of measured osmolality.

Background: Delayed hyponatremia after pituitary surgery can be treated with the V2-receptor antagonist, oral tolvaptan. We investigated the pharmacological effect of oral tolvaptan against SIAD in patients with hyponatremia after pituitary surgery. Methods: Thirty-nine patients with pituitary adenoma treated by endoscopic transsphenoidal surgery developed SIAD according to the major guidelines, and 7 patients (17.9%) were treated with tolvaptan. Tolvaptan was administrated orally half a tablet (3.75 mg) once in the first two cases, and half a tablet twice in the other five cases. Serum osmolality, urinary osmolality, urinary sodium concentration, urinary volume, and serum sodium and potassium concentration were evaluated before administration, and after the last oral administration of tolvaptan. Serum osmolality and urine osmolality were physically measured. Results: Serum sodium concentration was significantly increased from 132.1 ± 4.0 to 143.0 ± 2.9 mmol/L (mean ± standard deviation, n = 7, P < 0.001). Serum osmolality was significantly increased from 266.3 ± 7.7 to 289.6 ± 6.7 mOsm/kg (n = 7, P < 0.001). Urine osmolality was significantly reduced from 607.1 ± 240.4 to 262.7 ± 115.6 mOsm/kg (n = 7, P = 0.01). Urinary sodium concentration was significantly decreased from 121.3 ± 48.4 to 36.9 ± 35.0 mOsm/kg (n = 7, P = 0.001). Urine output (24-hour including the first administration) was significantly increased from 1384.2 ± 550.7 to 3291.3 ± 1710.9 mL/day (n = 6, P = 0.026). Conclusions: Oral tolvaptan administration corrects SIAD after pituitary surgery. Hyponatremia after pituitary surgery was confirmed to be due to SIAD.

Superior sagittal sinus dural arteriovenous fistula with changes in angiographic findings associated with contiguous parasagittal meningioma: A case report.

Background: Meningioma and dural arteriovenous fistula (dAVF) located at the same site are rare. The present case demonstrated the transformation of tumor feeding vessels into the pial feeder of the dAVF over time, which may help to elucidate the pathogenesis of tumor-associated dAVF. Case Description: A 71-year-old man presented with convulsion. Magnetic resonance (MR) imaging showed a right parasagittal sinus meningioma invading the superior sagittal sinus (SSS). Bilateral external carotid angiography showed dAVF at the SSS, near the site of tumor invasion. The right internal carotid angiography showed tumor staining from the anterior cerebral artery with intra-tumor arteriovenous shunting, with stagnation of tumor blood flow, suggesting impairment of perfusion to the SSS. Four years after the initial diagnosis, the patient was admitted to hospital with status epilepticus, and MR imaging showed an enlarged tumor. Carotid angiography revealed transformation of the tumor feeders to the pial feeder of the dAVF. The findings of shunting to the SSS had intensified, and stenosis had occurred in the posterior third of the SSS. The venous return showed retrograde flow anteriorly to the SSS. The patient underwent endovascular embolization and tumor resection. The shunt had disappeared. Conclusion: This report supports the proposal that impaired venous return is an important factor in the shunt occurrence of dAVF. Neurosurgeons should consider that cases of meningioma invading the venous sinuses may be complicated by dAVF and changes may occur over time.