Treatment of acromegaly by transsphenoidal microsurgery

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.

Gonadotrope Tumors

Gonadotrope tumors arise from the gonadotropes of the adenohypophysis. These cells rarely give rise to hyperplasia, usually only in the setting of long-standing premature gonadal failure. In contrast, gonadotrope tumors represent one of the most frequent types of pituitary tumors. Despite their relatively common occurrence, the pathogenesis of gonadotrope tumors remains unknown. Effective nonsurgical therapies remain out of reach. We review the pituitary gonadotrope from the morphologic and functional perspectives to better understand its involvement as the cell of origin of a frequent type of pituitary tumor.

Aggressive Pituitary Tumors or Localized Pituitary Carcinomas: Defining Pituitary Tumors

Pituitary tumors are common and exhibit a wide spectrum of hormonal, proliferative and invasive behaviors. Traditional classifications consider them malignant only when they exhibit metastasis. Patients who suffer morbidity and mortality from aggressive tumors classified as "adenomas" are denied support provided to patients with "cancers" and in many jurisdictions, these tumors are considered curiosities that do not warrant reporting in health registries. We propose use of the term "tumor" rather than "adenoma" to align with other neuroendocrine tumors. The features that can serve as diagnostic, prognostic and predictive markers are reviewed. Clinico-pathological and radiographic classifications provide important information and to date, no single biomarker has been able to offer valuable insight to guide the management of patients with pituitary tumors.

Postoperative persistent thyrotrophin releasing hormone-induced growth hormone release predicts recurrence in patients with acromegaly

OBJECTIVE

To assess the predictive value of postoperative thyrotrophin releasing hormone (TRH)-induced GH responsiveness in relation to (late) postoperative outcome in patients in remission after surgery for acromegaly.

PATIENTS

and methods One hundred and twenty-nine patients underwent surgery for acromegaly in our institution between 1977 and 1996. TRH tests and oral glucose tolerance tests (GTT) were performed and serum IGF-I concentrations were measured pre- and postoperatively and during follow-up. Criteria for postoperative remission were a mean serum GH concentration < 5 mU/l and/or serum GH after an oral glucose tolerance test < 1 mU/l immunofluorometric assay (IFMA) or < 2.5 mU/l (radioimmunosassay), together with a normal serum IGF-I concentration.

RESULTS

Preoperatively, the TRH-induced GH response was highly variable, with gradual overlap between 'nonresponders' and 'responders'. Arbitrarily defined as a doubling of serum GH concentration, 45.6% of patients were 'responders' to TRH. GH response after TRH injection was significantly correlated to the TRH-induced prolactin response but not to preoperative GH concentration or adenoma size. After surgery, remission was achieved in 83 of the 129 patients. Postoperative remission was significantly correlated to mean preoperative serum GH concentration and preoperative glucose-suppressed serum GH but not to tumour class. Seventy-one patients with early postoperative remission were followed without adjuvant treatment for a mean of 9.4 +/- 0.7 years (range 0-23 years). Forty-one of these patients were TRH responsive as defined by at least doubling of the serum GH concentration preoperatively. Of the 71 patients, 12 developed recurrence of disease, as defined by insufficient GH suppression during oral GTT, and elevated IGF-I and mean serum GH concentration. Irrespective of the preoperative response to TRH, the initial postoperative TRH test was predictive of developing disease recurrence with a sensitivity of 75% and a specificity of 100% when an absolute GH increase of 3.75 mU/l was chosen to define paradoxical responsiveness. A stimulated GH 1.6 times basal was predictive of recurrence with a sensitivity of 83% and a specificity of 73%, and 2.1 times basal was predictive with a sensitivity of 75% and a specificity of 80%. None of the 32 patients with postoperative normalization of the preoperatively present TRH-induced GH response, defined as a postoperative GH increase < 3.75 mU/l, developed recurrence of disease, while all nine patients with a GH increase above this level developed recurrence of acromegaly.

CONCLUSION

To our knowledge this is the first report which addresses the value of early postoperative TRH-induced GH responsiveness in predicting late surgical outcome using receiver-operating characteristic (ROC) curves to redefine a postoperative paradoxical response instead of arbitrarily chosen criteria. An absolute postoperative GH response of more than 3.75 mU/l was associated with recurrence in all nine patients, while all 32 patients with normalization of previously paradoxical response are still in remission. Our findings from this study demonstrate that the TRH test is a valuable tool in the early identification of patients at risk of developing postoperative recurrence of acromegaly.

Pituitary surgery in elderly patients with acromegaly

Because of the common belief that there is an increase in surgical risk and morbidity involved in the surgical therapy of elderly patients with acromegaly, physicians tend to either neglect therapy altogether or choose radiation therapy combined with medical treatment. In consideration of the expected increasing number of elderly patients resulting from social structure change in the coming years, we decided to investigate the outcome in 15 patients with acromegaly (13 women and 2 men) older than 64 years (mean, 68.3 yr) at the time of surgery in the form of a retrospective study. Medical treatment using either dopamine agonists (9 patients) and/or octreotide (4 patients) were attempted in 11 patients. For various reasons, however, medical therapy could not be permanently continued in any of these patients. The mean preoperative growth hormone (GH)-plasma level without medical treatment was 47.4 +/- 64.2 (mean +/- standard deviation) micrograms/L. At the time of operation, 13 of 15 patients had additional diseases, which led to an increased anesthesiological risk. Transnasal tumor removal was performed without anesthesiological or surgical complications in all patients. The radicality of tumor removal was controlled intraoperatively by GH measurements in eight patients. There was no postoperative mortality or serious morbidity. Postoperative basal GH-plasma levels were normal (< 4.5 micrograms/L) in all patients. None of the 13 patients who participated in long-term follow-up examinations (mean, 4.2 yr) revealed signs of definite tumor recurrence. The mean GH-plasma level at follow-up was 1.6 +/- 0.9 (mean +/- standard deviation) micrograms/L. One patient died 2 years after the operation of causes unrelated to pituitary surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of 24-hour growth hormone secretion in acromegaly: implications for diagnosis and therapy

OBJECTIVE

Early studies of acromegaly undertaken before the general availability of insulin-like growth factor I (IGF-I) assays have used arbitrary and varying growth hormone (GH) threshold levels for diagnosing and assessing outcome of treatment for this disease. We have undertaken a detailed study of GH secretion and its relationship to IGF-I levels to assess the usefulness of GH and IGF-I measurements in the assessment of acromegaly.

PATIENTS

Thirty acromegalic subjects (12 untreated and 16 previously treated) and 30 age and sex-matched normal subjects were studied.

MEASUREMENTS

Twenty-four-hour GH secretion was obtained from 20-minute sampling and serum IGF-I was measured. Comparisons were made of IGF-I, mean 24-hour GH concentration, and of the pulsatile and diurnal characteristics of GH secretion between the two groups.

RESULTS

IGF-I levels in untreated acromegaly were elevated and clearly separated from the normal range. Mean 24-hour GH concentrations in untreated and treated acromegalic subjects with elevated IGF-I (> 40 nmol/l) were greater than (P < 0.01), and showed good separation from, those of normal subjects only after age-matching. From the 24-hour profiles, nadir GH levels in normal subjects fell below the level of detectability while those in untreated acromegalic subjects did not. Pulse amplitude (P < 0.01), ratio of pulsatile to non-pulsatile GH release and the night to daytime GH ratio (P < 0.05) were significantly reduced in acromegaly. In the six patients who attained normal IGF-I levels after surgery, pulsatile characteristics remained abnormal in four. Mean 24-hour GH was significant related (r = 0.57) to IGF-I. A random GH concentration > 2.5 micrograms/l (5 mIU/l) has a sensitivity of 77% and specificity of 95% in identifying acromegalic patients who have biochemically active disease (elevated IGF-I) after treatment.

CONCLUSIONS

Patients with active acromegaly secrete more GH than age-matched normal controls. GH secretion in acromegaly is characterized by marked blunting of pulsatile secretion and, in contrast to normal subjects, the failure of GH to fall to undetectable levels at any time during the 24-hour day. IGF-I measurement is a more practical alternative in the diagnosis of acromegaly and in the assessment of therapeutic outcome. Since abnormalities of GH regulation may persist despite normalization of IGF-I, a distinction between remission and cure should be made. Detailed post-treatment evaluation of GH secretion is necessary to define the nature of underlying GH regulation and to evaluate the risk of disease recurrence.

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.

Postoperative prognostic indicators of control of acromegaly

Changes in growth hormone basal levels and growth hormone dynamic tests such as thyrotropin-releasing hormone and luteinizing hormone-releasing hormone tests, and the glucose tolerance test were evaluated during a follow-up period of 1-17 years in 17 acromegalic patients. In these cases, mean growth hormone basal levels obtained 1-2 months after surgery had dropped to levels below 5 ng/mL. In 11 of the patients, the 1-2 months postoperative mean growth hormone basal levels were reduced to less than 3 ng/mL. In these patients, abnormal growth hormone responses to these dynamic tests were not present and mean growth hormone basal levels remained below 3.0 ng/mL during the follow-up period of 1-6 years. In contrast, the six other patients' 1-2 months postoperative mean growth hormone basal levels were between 3 and 5 ng/mL. Of these, four presented abnormal responses in at least one of these three dynamic tests 1-2 months postoperatively, and three exhibited a rise in growth hormone basal levels after intervals of 1-3.5 years after surgery. It is concluded that the restoration of normal growth hormone response to the dynamic tests is better related to the value of the mean growth hormone basal levels obtained 1-2 months postoperatively being less than 3 ng/mL rather than it is to the conventional criterion of the growth hormone basal levels being less than 5 ng/mL.

Results of transsphenoidal microsurgery for growth hormone-secreting pituitary adenoma in a series of 214 patients

Of 214 patients with acromegaly who underwent transsphenoidal microsurgical resection of a pituitary adenoma, 54% had growth hormone (GH) levels below 5 ng/ml and 74% had levels less than 10 ng/ml immediately after surgery. Among the 174 patients who could be contacted for long-term follow-up review (average duration 76 months), most recent GH determinations were available for 165. Of these 165 patients, 131 (79.4%) have a GH level less than 5 ng/ml and 153 (92.7%) have a level below 10 ng/ml; these represent 75.3% and 87.9%, respectively, of the total 174 patients reviewed. Fifty-two patients received postoperative radiation therapy. Nine patients underwent reoperation. There were five cases of tumor recurrence following an apparent surgical cure (4.3%), nine new instances of anterior pituitary hypofunction (5%), and five failures of multimodality therapy (2.3%). There were no perioperative deaths, five cases of cerebrospinal fluid leak requiring surgical repair (2.2%), and four cases of postoperative meningitis (1.8%). Permanent diabetes insipidus did not occur. Two of 52 patients who were irradiated postoperatively had severe complications; 23 (54.8%) of 42 patients who were available for follow-up evaluation had developed panhypopituitarism; and eight (19%) of 42 had normal pituitary function an average of 44 months postirradiation.

Investigation of the criteria for assessing the outcome of treatment in acromegaly

The outcome of treatment in acromegaly is usually assessed by measuring plasma concentrations of growth hormone (GH)--either basal spontaneous levels or during hyperglycaemia. There is no consensus on how cure should be defined. Many studies have considered basal plasma growth hormone concentrations below 20 mU/l (10 ng/ml) as proof of cure, although some recent studies have applied lower values. At present a limit of 10 mU/l (5 ng/ml) seems to be accepted as evidence of cure. We have studied 28 acromegalic patients after transsphenoidal adenomectomy. Plasma GH concentrations (basal and during hyperglycaemia) as well as plasma somatomedin C (SMC) concentrations were measured and compared to the clinical symptoms. There was a close correlation between plasma GH and SMC concentrations (except when plasma GH levels were low) and between the clinical assessment and SMC concentrations. Very low plasma GH levels (less than 1 mU/l or 0.5 ng/ml) were associated with normal SMC values and clinical cure, high GH levels (greater than 10 mU/l or 5 ng/ml) with elevated SMC levels and persisting acromegaly. Moderately elevated plasma GH concentrations (1.9-9.6 mU/l) did not allow any conclusions on the outcome of treatment as assessed from SMC determinations and clinical evaluation. It is concluded that the usual criteria for cure in acromegaly may not be sufficiently strict.

Results of surgical management of 319 pituitary adenomas

Of the 510 patients with pituitary adenoma treated surgically at our hospital in the period 1956-1984 319 were treated by the microsurgical technique, in the period 1973-1984, 235 by transsphenoidal approach and 84 by subfrontal-pterional approach. The transsphenoidal route was used almost exclusively in microadenomas, in intrasellar adenomas, in suprasellar adenomas with midline development, in adenomas invading the sphenoidal sinus and in haemorrhagic adenomas with considerable suprasellar development. In some giant adenomas the transsphenoidal route was used in a first stage operation for debulking the tumour, later removed by transcranial route. The latter route was preferred in large adenomas and especially in adenomas with laterosellar development. In some patients with PRL secreting adenomas post-operative treatment with bromocriptine proved useful when the hormone levels failed to normalize. Post-operative radiotherapy was of value in invasive adenomas and in cases in which tumour removal was not radical.

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

In 44 patients with acromegaly treated by transsphenoidal pituitary microsurgery, the relationship between changes in pre- and post-operative GH dynamics and postoperative fasting plasma GH levels was examined to clarify which is the optimal approach for evaluating postoperative removal of the tumour. TRH, LHRH and bromocriptine tests, which act directly on the pituitary somatotroph, and the oral glucose tolerance test (oGTT) and insulin tolerance test (ITT), which act via hypothalamus, were carried out pre- and post-operatively. Abnormal responses postoperatively were found in most patients with fasting postoperative plasma GH over 5 ng/ml. In 24 patients with postoperative fasting plasma GH level of 5 ng/ml or below, 7 of 17 (41%) showed abnormal responses in the TRH test, 2 of 5 (40%) in the LHRH test and 3 of 13 (23%) patients in the bromocriptine test. All patients with a fasting plasma GH level less than 10 ng/ml, except for those with panhypopituitarism, showed normal responses to ITT and the paradoxical increases with the oGTT were absent. These results indicate that abnormal responses caused by a direct action on adenoma cells do not necessarily disappear even when the fasting plasma GH level is below 5 ng/ml. Abnormal responses caused by indirect actions, through the hypothalamus, disappear when the level is less than 10 ng/ml.

Transsphenoidal surgery following unsuccessful prior therapy. An assessment of benefits and risks in 158 patients

The authors report the results of a retrospective study conducted in an effort to define the results and risks of transsphenoidal surgery for patients whose prior therapy had failed. In a series of 1210 patients undergoing transsphenoidal surgery during a 10-year period, 158 had received prior therapy: 127 for pituitary adenoma, 20 for craniopharyngioma, and 11 for other lesions. Prior therapy was considered "direct" when it consisted of craniotomy or transsphenoidal surgery (either open or stereotaxic), and "indirect" when it consisted of radiation therapy, adrenalectomy, or bromocriptine therapy. The current transsphenoidal operation was performed for persistent hyperfunctioning endocrinopathy in 63 patients, for visual loss in 72 patients, and for cerebrospinal fluid (CSF) rhinorrhea in 21 patients. Success rates were as follows: normalization of endocrinopathy was achieved in 35% of cases; improvement or stabilization of vision in 59%; and successful repair of CSF rhinorrhea in 74%. The risks associated with repeat transsphenoidal surgery are significantly greater than the same procedure in a previously untreated patient.

Pathological diversity in clinical syndromes of pituitary hypersecretion: its significance in evaluating their surgical treatment

Through pathological examination disclosed considerable diversity of abnormal cell types and correspondingly different surgical correction rates among patients with apparently similar syndromes of pituitary hypersecretion. The surgical correction of acromegaly in patients with densely granulated growth hormone tumours was threefold that in patients whose tumours showed sparse granulation. Two non-prolactinoma tumour types associated with hyperprolactinemia have aggressive growth patterns; their special therapeutic management is discussed. Of 33 patients with Cushing's disease solitary adenomas were found in only 14, while six patients had proven corticotroph cell hyperplasia. Elective hypophysectomy should replace selective adenomectomy in selected cases of Cushing's disease.

Long-term growth hormone responses to nonspecific hypothalamic hormones in acromegalic patients

Nonspecific hypothalamic hormones such as thyrotropin-releasing hormone or luteinizing hormone-releasing hormone, or both, elicited abnormal growth hormone responses in 73 of 108 (67.6%) acromegalic patients. After transsphenoidal adenomectomy, the provocative tests using these hormones were repeated in 26 patients with abnormal preoperative growth hormone responses to study variations in these responses during a 1-8-year observation period (average duration, 4 years). After surgery, 7 of the 26 patients regained normal basal growth hormone levels (less than 5 ng/mL) and manifested normal responses to the hypothalamic hormones. During the postoperative observation period, their basal growth hormone levels remained normal as did their responses to provocation with hypothalamic hormones, confirming that the adenoma had been completely resected. Eight other patients demonstrated normal growth hormone levels after surgery; however, they continued to have abnormal responses to provocation with hypothalamic hormones, suggesting the presence of residual adenomatous tissue in the gland. These patients manifested no marked increase in basal or peak growth hormone levels during the follow-up period (from less than 1 to less than 7.5 years) and they were all in clinical remission without any other treatment. Only one incompletely adenomectomized patient who had received no additional treatment experienced regrowth of the tumor. The main factor affecting the surgical results appears to be the preoperative basal growth hormone level, because abnormal growth hormone secretion ceased in all patients who had manifested preoperative levels below 45 ng/mL. Technical refinements of the operative procedure are another important factor in the postoperative outcome. Peritumoral tissue resection after simple selective adenomectomy is mandatory for better surgical results. Our studies indicate that fairly good results can be obtained without risk of the recurrence of the tumor or regrowth, when postoperative growth hormone levels are below 5 ng/mL and that the results are not affected by the postoperative growth hormone responses to provocation with hypothalamic hormones.

The pathogenesis of acromegaly. Clinical and immunocytochemical analysis in 75 patients

A series of 75 patients with acromegaly and immunocytochemically characterized pituitary adenomas has been analyzed. Tumors secreting growth hormone (GH) only were found in 21% of cases. The remainder had tumors immunoreactive for more than one pituitary hormone: GH and prolactin in 31%; GH, prolactin, and glycoprotein in 40%; and GH and glycoprotein in 8%. Microadenomas were surgically treated in 17 patients with a success rate of 82%. Overall, normalization of basal GH secretion (to less than or equal to 5 ng/ml) was achieved in 54% of cases. The implications of these findings for the pathogenesis and neurosurgical management of acromegaly are discussed.

Transsphenoidal surgery for acromegaly--long-term results in 100 patients

A series of 100 patients with acromegaly who were operated on using the transsphenoidal microsurgical approach is presented along with a review of the literature. Emphasis is placed on long-term follow-up to assess the value of the technique. The authors caution against early normalization of growth hormone as a criterion for biologic cure in that cases of late recurrence are presented. It is proposed that 5 ng/mL baseline growth hormone values with normal dynamic testing is the most reliable way to ascertain biologic cure. Using these criteria, a cure rate of 78% for enclosed and 33% for invasive adenomata was obtained. No long-term recurrence was seen in patients considered cured along these lines.

A decade of pituitary microsurgery. The Herbert Olivecrona lecture

The author reviews his experience with surgical treatment of 1000 pituitary tumors, the majority of which were endocrine-active. The criteria of grading, the microsurgical technique used, and the postoperative results are presented. The mortality rate was 0.2% overall, with no deaths in the group of 774 patients with endocrine-active adenomas.

Clinical use of pre- and postsurgical evaluation of abnormal GH responses in acromegaly

The criteria by which acromegalic patients are considered "cured" after surgical therapy are still controversial. Since the abnormal growth hormone (GH) increase after the administration of some agents has been demonstrated to be characteristic of the tumoral somatotrophs, its disappearance after surgery may be taken as an index of the complete removal of the tumor. Serum GH increases after thyrotropin-releasing hormone (TRH, 200 micrograms intravenously), gonadotropin-releasing hormone (Gn-RH, 100 micrograms intravenously), and sulpiride (100 mg intramuscularly) injected during dopamine infusion (DA-Slp test), were evaluated in 68 acromegalic patients before and after transnasosphenoidal adenomectomy, and every 12 to 18 months during a follow-up period of 6 months to 11 years (average 42 months). Forty-two patients had abnormal responses to at least one test before surgery: 32 out of 68 (47%) to TRH, six out of 40 (15%) to Gn-RH, and 20 out of 28 (71%) to the DA-Slp test. Of 18 patients who underwent all three tests, 78% had abnormal responses to at least one of them. Twenty-three patients became unresponsive after surgery, and none of them had a recurrence or became abnormally responsive again during the follow-up period. Three out of six patients with postoperative serum GH levels between 5.1 and 10 ng/ml and three out of six patients with postoperative serum GH levels between 2.1 and 5 ng/ml remained abnormally responsive: one of them relapsed 1 year after the operation. The abnormal responses were lost in all 11 patients whose postoperative serum GH levels were below 2 ng/ml, and abnormal responses were maintained in all the patients in whom surgery was considered unsuccessful because postoperative serum GH levels were higher than 10 ng/ml. The TRH, Gn-RH, and DA-Slp tests should thus be considered useful tools in verifying the total removal of an adenoma. The reappearance of active acromegaly in the patient with low postoperative GH levels, who was still responsive to TRH, should be regarded as a reactivation and not a true recurrence of the disease.

Transsphenoidal microsurgical removal of growth hormone-secreting pituitary adenomas. A review of 137 cases

A series of 137 patients with growth hormone (GH)-secreting pituitary adenomas were treated by transsphenoidal surgery during a 10-year period. Group A comprised patients for whom this surgery was the first therapeutic interventions, and Group B included those who underwent the surgery after previous therapeutic intervention. The results were analyzed considering preoperative and postoperative endocrinological, neurological, ophthalmological, and neuroradiological data. Remission was defined as clinical response and a normal postoperative GH level, and partial remission at clinical response and postoperative reduction of the GH level by more than 50%. Any other result was considered failure. The mean follow-up period was 37.1 months; follow-up review was achieved in all the patients. Among the 102 patients in Group A, remission was achieved in 80 (78%) patients with transsphenoidal surgery alone, and in an additional 16 (16%) after postoperative irradiation (combined response rate, 94%). All failures and patients with partial remission had preoperative GH levels of more than 50 ng/ml and suprasellar extension of the tumor. There were no deaths; 8% of patients had minor surgical morbidity; 5% had new hypopituitarism postoperatively. Of patients subsequently irradiated, 71% developed hypopituitarism. Among the 35 patients in Group B, remission was achieved in 26 (74%), partial remission was obtained in two (6%), and seven (20%) were considered treatment failures. There were no deaths, and the morbidity rate was 14%; 66% of patients had hypopituitarism postoperatively. Of the eight patients who had received prior irradiation only, seven (88%) went into remission. All failures and partial responders had preoperative GH levels greater than 40 ng/ml; 56% had suprasellar extension. These results confirm the efficacy of the transsphenoidal approach for the treatment of GH-secreting pituitary adenomas.

Neurosurgical management of acromegaly. Results in 82 patients treated between 1972 and 1977

A consecutive series of 82 acromegalic patients who underwent transsphenoidal surgery during a 5-year period is presented. Preoperative and postoperative values for human growth hormone (HGH) were available in 80 cases. Microadenomas were present in 18 patients with a mean preoperative HGH value of 25.2 ng/ml, diffuse adenomas in 39 patients with mean of 53.8 ng/ml, and invasive adenomas in 25 with mean of 68.0 ng/ml. There was no operative mortality. The results reflected the classification of the tumors, with apparent cures accomplished in 87.5% of previously untreated patients with microadenoma, all of whom had anterior pituitary function preserved. The percentages of apparent cures in cases of diffuse adenoma (68%) and invasive adenoma (54%) were much less satisfactory. Transsphenoidal microsurgery is capable of achieving good results, particularly in patients with microadenoma.

Functional treatment of acromegaly by transsphenoidal microsurgery

The authors have analyzed the results from 41 acromegalic patients who underwent transsphenoidal surgery. In 31 patients, postoperative growth hormone (GH) levels fell and remained below 10 ng/ml. This represents an endocrinological "cure" of 78%. In the remaining 10 cases, postoperative GH values have not stabilized below 10 ng/ml, although seven show some clinical improvement. The results were particularly good in those cases of localized adenomas, which allowed a selective removal while maintaining pituitary function within normal limits in 65.5% of cases. The postoperative GH level in this group fell and remained below 10 ng/ml in more than 90% of cases. Four patients required reoperation to normalize the GH levels which had not been sufficiently modified after the first operation; only one of them remained with plasma GH levels above normal limits. There were no deaths in this series. Rhinorrhea occurred as a postsurgical complication in four cases. In three this disappeared with bed rest and lumbar drainage; in the other, surgical repair was necessary. The occurrence of surgical complications has decreased as our experience has increased, and the need for reoperation has been unusual after the first year of our study.

Evaluation of the results of trans-sphenoidal surgery in acromegaly by assessment of the growth hormone response to thyrotrophin-releasing hormone

Eighteen acromegalic patients GH-responsive to TRH were reinvestigated following trans-sphenoidal surgery and radiotherapy. Basal serum GH decreased below 10 microgram/1 in thirteen cases; nine of them became GH-unresponsive to TRH 1 month after operation, and another one following conventional pituitary irradiation. Four of these ten patients also showed a normal GH response to L-Dopa after treatment, and five responded normally to insulin-induced hypoglycaemia; two patients had a normal GH secretory pattern after both these stimuli. No recurrences were observed over a follow-up period of 15-80 months among the ten patients who became GH-unresponsive to TRH following operation, while one of the three subjects still responsive to TRH in spite of normalized basal serum GH concentration relapsed 10 months after surgery. Three patients with normalized TRH test following operation were repeatedly reinvestigated over a 3-6 years period and always found unresponsive. The present study shows that the 'paradoxical' GH responses to TRH and L-Dopa frequently disappear after surgery, that complete normalization of GH secretory pattern may rarely be attained, and that the disappearance of GH response to TRH probably indicates satisfactory treatment of acromegaly. These data suggest that the 'paradoxical' GH responses frequently found in acromegaly are dependent on the adenoma per se and not on hypothalamic dysfunction.

Clinical and endocrinological evaluation of 16 acromegalic patients treated by transsphenoidal surgery

Sixteen patients with acromegaly treated with transsphenoidal pituitary surgery were evaluated with the measurement of serum human growth hormone (HGH) before and after intravenous stimulation with thyrotropin-releasing hormone (TRH). Fourteen of these patients showed a significant rise of serum HGH after TRH stimulation before surgery. After surgery, 12 patients with Grade 2 noninvasive adenomas had normal fasting serum HGH levels which did not stimulate with TRH. Two of these patients showed high serum HGH levels both at fasting and after TRH stimulation and required a second operation to remove residual adenoma within the sella before adequate lowering of HGH was achieved. Evidence of recurrent adenoma has not occurred clinically or biochemically in this group of 12 patients followed for an average of 24 months (2 to 60 months). The results were unsatisfactory in four of these 16 patients. One patient who has a postoperative HGH of 9 ng/ml which still stimulates with TRH has made clinical improvement, but must have residual adenoma in the sella or invasive adenoma in the dura and tumor capsule. Additional treatment with irradiation has been given. Failure to achieve satisfactory results in the other three patients was attributed to the presence of locally invasive adenoma; one in the sphenoid sinus, and the other two possibly as a consequence of previous operative procedures.