Significance of postoperative fluid diuresis in patients undergoing transsphenoidal surgery for growth hormone-secreting pituitary adenomas.

OBJECT: Following successful transsphenoidal surgery in patients with growth hormone (GH)-secreting pituitary adenomas, a characteristic fluid diuresis has been described. In this paper the authors aimed to further analyze the degree of fluid diuresis as it relates to postoperative GH levels. METHODS: Between 2000 and 2008, 85 patients underwent transsphenoidal surgery for a GH-secreting adenoma at the USC University Hospital. A retrospective chart review was conducted. Postoperative fluid intake, output, and balance within 48 hours following surgery, as well as endocrinological data were recorded and analyzed. Patients with postoperative diabetes insipidus and those with insufficient data were excluded from analysis. RESULTS: Seventy-one patients were included in the analysis. The mean age was 46 years (range 16-74 years). There were 36 males (51%) and 35 females (49%). Patients with negative fluid balances at 48 hours after surgery were more than twice as likely to have a GH level of < 1.5 ng/ml (55 vs 25%, p = 0.023). At 48 hours after surgery, patients with a negative overall fluid balance had a significantly lower median GH level than those with a positive overall fluid balance (1.3 vs 2.4 ng/ml, p = 0.039). This difference was even more pronounced in patients with microadenomas and a negative overall fluid balance. By 48 hours following surgery, patients with postoperative Day 1 GH levels < 1.5 ng/ml had, on average, experienced diuresis of fluid > 1.1 L (median 1.5 L) more than patients with GH levels > 1.5 ng/ml. CONCLUSIONS: Successful resection of GH-secreting adenomas is associated with a more pronounced fluid diuresis and negative overall fluid balance within 48 hours following transsphenoidal surgery. Patients with a negative fluid balance by postoperative Day 2 have a higher likelihood of having significantly reduced postoperative GH levels that may correlate with long-term surgical remission.

Postoperative Gamma Knife surgery for benign meningiomas of the cranial base.

OBJECT: The standard treatment for meningiomas is complete resection, but the proximity of skull base meningiomas to important neurovascular structures makes complete excision of the lesion difficult or impossible. The authors analyzed the mid- and long-term results obtained in patients treated with postresection Gamma Knife surgery (GKS) for residual or recurrent benign meningiomas of the cranial base. METHODS: Thirty-six patients with residual or recurrent benign meningiomas of the skull base following one or more surgical procedures underwent GKS. There were 31 women and five men, ranging in age from 22 to 73 years. The median tumor volume was 4.1 ml (range 0.8-20 ml) and the median radiation dose to the tumor margin was 16 Gy (range 15-16 Gy). RESULTS: Patients were followed for a median of 81 months (range 30-141 months) after GKS. At the end of the follow-up period, overall neurological improvement was observed in 16 patients (44.4%), whereas the condition in 20 patients (55.6%) was unchanged. One patient suffered transient cerebral edema 6 months after GKS. Based on imaging documentation, a partial response was seen in five patients (13.9%), the disease remained stable in 30 patients (83.3%), and in one patient (2.8%) there was an increase in tumor size. The actuarial progression-free survival rate was 100% at 5 years and 94.7% at 10 years. CONCLUSIONS: Gamma Knife surgery was shown to be an excellent adjunct to resection because of its durable rate of tumor control and low toxicity. It should be initially considered along with surgery for the treatment of complex skull base meningiomas.

Recognition and management of delayed hyponatremia following transsphenoidal pituitary surgery.

OBJECT: The goal of this study was to assess the incidence of symptomatic and occult hyponatremia in patients who had undergone transsphenoidal pituitary surgery. METHODS: Patients who underwent transsphenoidal surgery at the University of Southern California University Hospital between 1997 and 2004 had serum sodium levels drawn on an outpatient basis on postoperative Day 7. Patient records were retrospectively reviewed to determine the incidence of, and risk factors for, symptomatic and asymptomatic hyponatremia. Two hundred forty-one patients had routine serum sodium levels drawn as outpatients on postoperative Day 7. Twenty-three percent of these patients were found to be hyponatremic (Na < or =135 mEq/L). The overall incidence rate of symptomatic hyponatremia in the 241 patients was 5%. The majority of hyponatremic patients (80%) remained asymptomatic, whereas 20% became symptomatic. In patients with symptomatic hyponatremia, the mean sodium level at diagnosis was 120.5 mEq/L, compared with 128.4 mEq/L in asymptomatic, hyponatremic patients (p < 0.0001). Female patients were more likely to develop hyponatremia than male patients (33% compared with 22%, p < 0.03). Fifty-two percent of patients who had transient diabetes insipidus (DI) early in their postoperative course subsequently developed hyponatremia, compared with 21% of those who did not have DI (p < 0.001). Patient age, tumor type, and tumor size did not correlate with development of delayed hyponatremia. Outpatients with moderately and severely low sodium levels were 5 and 12.5 times more likely, respectively, to be symptomatic than were patients with mild hyponatremia. CONCLUSIONS: Delayed hyponatremia occurs more frequently than was previously suspected in patients who have undergone transsphenoidal surgery, especially in female patients and those who have previously had transient DI. The majority of hyponatremic patients remain asymptomatic. Obtaining a serum sodium value on an outpatient basis 1 week after pituitary surgery is helpful in recognition, risk stratification, and subsequent intervention, and may prevent potentially serious complications.