Postoperative plasma GH levels and restoration of GH dynamics in acromegalic patients surgically treated by the transsphenoidal approach

Microsurgical versus endoscopic transsphenoidal resection for acromegaly: a systematic review of outcomes and complications

PURPOSE

The aim of this systematic review is to evaluate the long-term endocrine outcomes and postoperative complications following endoscopic vs. microscopic transsphenoidal resection (TSR) for the treatment of acromegaly.

METHODS

A literature review was performed, and studies with at least five patients who underwent TSR for acromegaly, reporting biochemical remission criteria and long-term remission outcomes were included. Data extracted from each study included surgical technique, perioperative complications, biochemical remission criteria, and long-term remission outcomes.

RESULTS

Fifty-two case series from 1976 to 2016 met the inclusion criteria, comprising 4375 patients. Thirty-six reports were microsurgical (n = 3144) and 13 were endoscopic (n = 940). Three studies compared microsurgical (n = 111) to endoscopic TSR outcomes (n = 180). The overall initial and long-term remission rates were 58.2 vs. 57.4% and 69.2 vs. 70.2% for the microsurgical and endoscopic groups, respectively. For microadenomas, the initial and long-term remission rates were 77.6 vs. 82.2% and 76.9 vs. 73.5% for microsurgical and endoscopic approaches, respectively. For macroadenomas, the initial and long-term remission rates were 46.9 vs. 60.0% and 40.2 vs. 61.5% for microsurgical and endoscopic approaches, respectively. The rates of postoperative CSF leak were 3.0 vs. 2.3% for the microscopic and endoscopic groups, respectively. The rates of hypopituitarism and transient diabetes insipidus were 6.7 vs. 6.4% and 9.0 vs. 7.8% for the microscopic and endoscopic groups, respectively.

CONCLUSIONS

Both endoscopic and microsurgical approaches for TSR of growth hormone-secreting adenomas are viable treatment options for patients with acromegaly, and yield similarly high rates of remission under the most current consensus criteria.

Lack of menstrual cycle effects on hypothalamic-pituitary-adrenal axis response to insulin-induced hypoglycaemia

OBJECTIVE

Limited data are available on the effects of the menstrual cycle on the hypothalamic-pituitary-adrenal axis (HPA) function. This study evaluates HPA axis reactivity to insulin-induced hypoglycaemia over the menstrual cycle.

PATIENTS

Twelve normal women were randomized to placebo and evaluated during three successive menstrual cycles. Menstrual phase was documented by menstrual diary and by oestradiol and progesterone levels at the time of each insulin tolerance test (ITT). Six normal men were included as a comparison in the statistical analysis.

MEASUREMENTS

Afternoon ITTs were performed initially on the second or third day of menses in women, then seven more ITTs followed at one or two week intervals during the next 10 weeks. Serum measurements of glucose, adrenocorticotrophin (ACTH) and cortisol were obtained.

RESULTS

The glucose and ACTH responses to the ITTs were similar between men and women. Cortisol levels at baseline and during the test were higher in men than in women, although the amount of change was similar. Glucose, ACTH and cortisol response to insulin-induced hypoglycaemia did not vary over the menstrual cycle or during repeat testing in men or women.

CONCLUSIONS

These data show that it is unnecessary to control for menstrual cycle during insulin tolerance tests performed at 1600 hours. It is, however, necessary to control for the effect of sex on cortisol levels. Repeat testing more than one week apart does not appear to influence the glucose, ACTH or cortisol response to insulin stress.

Treatment of invasive growth hormone pituitary adenomas with long-acting somatostatin analog SMS 201-995 before transsphenoidal surgery

The purpose of this study was to determine whether the long-acting somatostatin analog SMS 201-995 (octreotide) shrinks growth hormone (GH)-secreting adenomas and improves the results of subsequent transsphenoidal surgery. Ten previously untreated active acromegalic patients (nine women and one man) with invasive tumors were treated with SMS 201-995 (100 micrograms subcutaneously every 8 hours) for 6 weeks prior to transsphenoidal surgery. The clinical activity, mean GH secretion, insulin-like growth factor (IGF)-I concentration, and tumor volume were measured under basal conditions and on Days 14, 28, and 42 of treatment. The SMS 201-995 improved the symptoms of acromegaly in all patients. Mean levels of both GH and IGF-I (+/- standard deviation) were significantly decreased by Day 14 (from 92.9 +/- 30.5 to 44.9 +/- 20.3 micrograms/liter and from 10.6 +/- 7.4 to 5.9 +/- 2.6 U/ml, respectively), after which there were only slight further decreases. Six (60%) of the 10 patients experienced tumor shrinkage ranging from 9% to 78% (mean 30%). When it occurred, tumor shrinkage was significant by Day 14 (7.9 +/- 6.3 to 6.5 +/- 5.1 cu cm) and no further shrinkage was achieved by longer administration. Transsphenoidal surgery reduced postoperative GH levels to less than 2 micrograms/liter and IGF-I to less than 1.5 U/ml in six patients (60%). This percentage of cure is higher than expected from the literature and the authors' previous experience. However, an investigation of the influence of this drug on several parameters, such as reduction of tumor size or GH and IGF-I concentrations, has failed to prove any relationship. Only pretreatment size of the tumor was of predictive value with respect to the surgical outcome.

Transsphenoidal adenomectomy for growth hormone-secreting pituitary adenomas in acromegaly: outcome analysis and determinants of failure

The results of transsphenoidal adenomectomy for growth hormone (GH)-secreting pituitary adenomas in acromegaly performed over a 17-year period were analyzed retrospectively to determine which preoperative factors significantly influenced the long-term surgical outcome. These variables were then used to develop a logistic regression model to determine the probability of surgical failure. The series consisted of 103 patients. Long-term follow-up study (mean duration 102 +/- 64 months) was performed to derive outcome analysis and determinants of failure. Surgical control was defined as a long-term postoperative serum basal GH level of less than 5 micrograms/liter, a long-term postoperative serum somatomedin C (SM-C) level of less than 2.2 U/ml, and a favorable clinical response. Eighteen (17.5%) patients did not meet these criteria. The overall control rate by the GH criteria was 81.3% and by the SM-C criteria 76.2%. By multivariate logistic regression analysis, tumor stage was the strongest predictor of outcome (p < 0.05). The preoperative GH level, tumor grade, and preoperative SM-C level were significant univariate predictors (p < 0.05). There were statistically significant differences in mean preoperative GH and SM-C levels (p < 0.05, t-test) and tumor stage (p < 0.05, chi-squared test) between patients whose acromegaly was controlled by surgery and those whose acromegaly was not. Furthermore, estimates were derived of the probability of surgical failure based on preoperative GH level, preoperative SM-C level, and tumor grade and stage. The authors believe these findings will enhance clinical decision-making for neurosurgeons considering transsphenoidal microsurgery in patients with acromegaly.

Evaluation of selective transsphenoidal adenomectomy by endocrinological testing and somatomedin-C measurement in acromegaly

A series of 29 previously untreated patients with acromegaly underwent transsphenoidal adenomectomy. Pre- and postoperative evaluation consisted of measuring growth hormone (GH) secretory dynamics during an oral glucose tolerance test (OGTT), the insulin hypoglycemia test, and the thyrotropin- and gonadotropin-releasing hormone (TRH/GnRH) test, and by obtaining the basal somatomedin-C level. After surgery, clinical and biochemical amelioration was achieved in all but two patients. In the whole group, basal GH and somatomedin-C levels decreased from a mean (+/- standard error of the mean) of 52.3 +/- 12.7 to 11.1 +/- 6.3 ng/ml and from 7.6 +/- 0.7 to 2.5 +/- 0.5 U/ml, respectively. Application of different criteria of cure revealed that 19 patients (66%) had basal GH levels below 5 ng/ml, 17 patients (59%) had normal somatomedin-C values, 16 patients (55%) had complete GH suppression (less than 1 ng/ml) during OGTT, and 13 patients (45%) met the above-mentioned criteria with disappearance of the paradoxical GH response to TRH/GnRH test. Evaluation of GH secretion by insulin hypoglycemia testing was useless in assessing the outcome after neurosurgery. When only patients with a normal somatomedin-C level and complete GH suppressibility during OGTT were considered "cured," the main favorable prognostic factor was intrasellar tumor localization, since 15 (75%) of 20 patients were "cured," as opposed to only one (11%) of nine with extrasellar extension of the adenoma. During the follow-up period, no tumor recurrence was detected in any of the "cured" patients. In these subjects somatomedin-C levels remained stable in all except two patients, who showed a slow increase within the normal range of somatomedin-C concentration. These data confirm that transsphenoidal surgery is the most effective form of treatment in previously untreated acromegalic patients and that normalization of somatomedin-C levels reflects normal GH secretion. Measurement of somatomedin-C could replace more extensive endocrinological testing during monitoring of treated acromegalic patients.