Fluid balance and secretion of antidiuretic hormone following transsphenoidal pituitary surgery. A preliminary series

Advancement in perioperative management of pituitary adenomas-Current concepts and best practices

Pituitary adenomas are very common representing 18.1% of all brain tumors and are the second most common brain pathology. Transsphenoidal surgery is the mainstay of treatment for all pituitary adenomas except for prolactinomas which are primarily treated medically with dopamine agonists. A thorough endocrine evaluation of pituitary adenoma preoperatively is crucial to identify hormonal compromise caused by the large sellar mass, identifying prolactin-producing tumors and comorbidities associated with Cushing and acromegaly to improve patient care and outcome. Transsphenoidal surgery is relatively safe in the hands of experienced surgeons, but still carries a substantial risk of causing hypopituitarism that required close follow-up in the immediate postoperative period to decrease mortality. A multidisciplinary team approach with endocrinologists, ophthalmologists, and neurosurgeons is the cornerstone in the perioperative management of pituitary adenomas.

Delayed postoperative hyponatremia in patients with acromegaly: incidence and predictive factors

PURPOSE

Delayed postoperative hyponatremia (DPH) is a unique complication of transsphenoidal surgery (TSS) in pituitary tumors. Growth hormone (GH) enhances renal sodium reabsorption; however, the association between postoperative GH reduction and DPH in acromegaly is unclear. This study was performed to clarify the incidence of and the predictive factors for DPH in patients with acromegaly who underwent TSS.

METHODS

Ninety-four patients with active acromegaly were examined retrospectively. During the postoperative course, patients with serum sodium levels ≤ 134 mEq/L were classified into the DPH group. We compared basic clinical characteristics, tumor characteristics, and preoperative and postoperative examination findings between the DPH and non-DPH groups.

RESULTS

DPH occurred in 39 patients (41.5%), and the lowest serum sodium levels were generally observed during postoperative days (PODs) 7-9. They needed a 3-day longer hospital stay than those without DPH. The DPH group had lower preoperative body weight and body mass index. In addition, a transient increase in body weight during PODs 5-7 occurred with a transient decrease in urinary volume in the DPH group. Preoperative and postoperative GH and insulin-like growth factor-1 levels did not differ between the two groups.

CONCLUSION

The findings suggested that lower preoperative weight and a postoperative transient gain in body weight are associated with an increased risk of DPH in acromegaly patients undergoing transsphenoidal surgery.

The Cost Effectiveness of Implementation of a Postoperative Endocrinopathy Management Protocol after Resection of Pituitary Adenomas

Purpose  After developing a protocol for evaluating, diagnosing, and treating postoperative endocrinopathy both during the hospitalization and during the immediate discharge period following resection of pituitary adenomas, we sought to assess the impact of this protocol on quality outcomes. Methods  An IRB-exempt, quality improvement initiated, Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective comparison of a pre-and-post-protocol cohort of all patients undergoing endoscopic endonasal resection of pituitary adenomas at NYU Langone Medical Center from January 2013 to December 2018. Demographic characteristics of the patients and their tumors with their postoperative outcomes were recorded. Quality outcomes regarding number of laboratory studies sent, rate of diabetes insipidus, length of stay, and readmission rate were also recorded. Statistical analysis was performed between the pre- and post-protocol groups. Results  There was a significant reduction in laboratory studies sent per patient (55.66 vs. 18.82, p <0.001). This corresponded with an overall cost reduction in laboratory studies of $255.95 per patient. There was a decrease in the overall number of patients treated with DDAVP (21.4% in the pre-protocol group vs. 8.9% in the post-protocol group, p  = 0.04). All post-protocol patients requiring DDAVP at discharge were identified by 48 hours. There was no significant change in length of stay or need for hydrocortisone supplementation postoperatively between the two groups. Length of stay was driven mostly by need for reoperation during initial hospitalization. There was no significant change in the rate of 30-day readmission. Conclusion  Implementation of a postoperative management protocol results in a more efficient diagnosis and management of endocrinopathy after pituitary adenoma surgery which translates to decreased cost.

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.

Delayed Hyponatremia after Transsphenoidal Surgery for Pituitary Adenomas: A Single Institutional Experience

Background

Hyponatremia is a common complication after transsphenoidal surgery (TSS) for pituitary adenomas. This study retrospectively reviewed various clinical factors of pituitary adenoma patients who underwent TSS and aimed to identify possible risk factors of postoperative hyponatremia.

Methods

Total 1,343 patients who underwent TSS for their pituitary adenomas in a single institution were enrolled to this study. We identified and analyzed 93 patients (6.9%) with postoperative hyponatremia and compared them with other 1,250 patients in a control group. Patients' age, sex, tumor extent based on the modified Hardy classification, tumor size and hormonal type of the tumors were analyzed in comparison between two groups. The results of pre- and post-operative combined pituitary function test and their comparison were analyzed to elucidate a possible association between postoperative hyponatremia and hypopituitarism.

Results

The onset of postoperative hyponatremia was 7.8 days after surgery (range: postoperative day 3–13). The initial level of serum sodium (Na) level at the start of treatment was 123.5 mmol/L (range: 114–131 mmol/L) and the duration of treatment was 2.7 days (range: 1–9 days). Female predominance was evident in the hyponatremia group (77.4% vs. 61.4%, p=0.02). Preoperative hypopituitarism (58.5% vs. 71.5%, p=0.007) and postoperative hypocortisolism (33.7% vs. 23.4%, p=0.029) were related to postoperative hyponatremia. Other pre- and post-operative clinical factors were not associated with postoperative hyponatremia.

Conclusion

Postoperative hyponatremia is a common complication after TSS and is potentially fatal. Female patients were more likely to develop delayed hyponatremia. We demonstrated possible associations of delayed postoperative hyponatremia with preoperative and postoperative pituitary functions, but the mechanism behind it should be further investigated.

Implementation of a Postoperative Outpatient Care Pathway for Delayed Hyponatremia Following Transsphenoidal Surgery

BACKGROUND

After transsphenoidal surgery, delayed hyponatremia (DH) is the leading cause of 30-d unplanned hospital readmissions.

OBJECTIVE

To determine the impact of a DH care pathway on 30-d readmissions after transsphenoidal surgery.

METHODS

Data from before and after DH care pathway implementation were retrospectively reviewed. Patient demographics and clinical characteristics were compared. Readmission causes, clinical pathway failures, sodium trends, and symptoms were evaluated.

RESULTS

Before the DH care pathway implementation, 229 (55%) patients were treated (group 1); afterward, 188 (45%) were treated (group 2). Baseline characteristics were equivalent between groups, except for glucocorticoid supplementation, which was higher in group 2. The incidence of detected DH was significantly lower in group 1 (16/229, 7%) than group 2 (29/188, 15%) (P = .006) likely due to the impact of routine screening in group 2. Ten group 1 patients (4%) were readmitted for hyponatremia and 6 (3%) were managed as outpatients. Eleven group 2 patients (6%) were readmitted and 17 (9%) were managed as outpatients. Readmission rates between groups were similar (P = .49). Patients readmitted with severe hyponatremia experienced symptoms ≥24 h before presentation. The protocol failed to prevent readmission because outpatient management for mild or moderate DH (n = 4) failed, sodium levels precipitously declined after normal screening (n = 3), and severe hyponatremia developed after scheduled screenings were missed (n = 3).

CONCLUSION

Although more DH patients were identified after care pathway implementation, readmission rates were not reduced and clinical outcomes were not changed. Because DH onset timing varies, some patients have highly acute presentation, and most readmitted patients develop symptoms before reaching their sodium nadir, close symptom monitoring may be a reasonable alternative to routine screening.

Postoperative Diabetes Insipidus and Hyponatremia in Children after Transsphenoidal Surgery for Adrenocorticotropin Hormone and Growth Hormone Secreting Adenomas

OBJECTIVES

To define the incidence and risk factors of postoperative sodium alterations in pediatric patients undergoing transsphenoidal surgery (TSS) for adrenocorticotropic hormone and growth hormone secreting pituitary adenomas.

STUDY DESIGN

We retrospectively reviewed 160 patients ≤18 years of age who had TSS for pituitary adenomas at our institution from 1999 to 2017. Variables included daily serum sodium through postoperative day 10, urine specific gravity, and medications administered. We examined associations between sex, repeat surgery, manipulation of the posterior pituitary (PP), tumor invasion into the PP, tumor type and size, cerebrospinal fluid (CSF) leak, lumbar drain insertion, body mass index, puberty, and development of diabetes insipidus (DI) or syndrome of inappropriate antidiuretic hormone secretion (SIADH).

RESULTS

Mean age was 12.9 ± 3.4 years (female = 81). Patients had adrenocorticotropic hormone (150/160) and growth hormone (10/160) producing adenomas. Forty-two (26%) patients developed DI. Among the 37 of 160 who required desmopressin acutely, 13 of 37 required it long term. Risk of long-term need for desmopressin was significantly higher in patients who had CSF leak 9 of 48 (P = .003), lumbar drain 6 of 30 (P = .019), manipulation 11 of 50 (P < .001), or invasion 4 of 15 (P = .022) of the PP. Sixty patients developed hyponatremia, 19 because of SIADH, 39 to hypotonic fluids and 2 to cerebral salt wasting syndrome. Patients with SIADH were placed on fluid restriction; 1 received salt tablets.

CONCLUSIONS

Among 160 children who underwent TSS for pituitary adenomas, the incidence of DI and SIADH after TSS was 26% and 14%, respectively. Combined risk factors for DI and/or SIADH include female sex, manipulation of and/or tumor invasion into the PP, and CSF leak or lumbar drain.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00001595 and NCT00060541.

Incidence, Etiology and Outcomes of Hyponatremia after Transsphenoidal Surgery: Experience with 344 Consecutive Patients at a Single Tertiary Center

Hyponatremia is often seen after transsphenoidal surgery and is a source of considerable economic burden and patient-related morbidity and mortality. We performed a retrospective review of 344 patients who underwent transsphenoidal surgery at our institution between 2006 and 2012. Postoperative hyponatremia was seen in 18.0% of patients at a mean of 3.9 days postoperatively. Hyponatremia was most commonly mild (51.6%) and clinically asymptomatic (93.8%). SIADH was the primary cause of hyponatremia in the majority of cases (n = 44, 71.0%), followed by cerebral salt wasting (n = 15, 24.2%) and desmopressin over-administration (n = 3, 4.8%). The incidence of postoperative hyponatremia was significantly higher in patients with cardiac, renal and/or thyroid disease (p = 0.0034, Objective Risk (OR) = 2.60) and in female patients (p = 0.011, OR = 2.18) or patients undergoing post-operative cerebrospinal fluid drainage (p = 0.0006). Treatment with hypertonic saline (OR = −2.4, p = 0.10) and sodium chloride tablets (OR = −1.57, p = 0.45) was associated with a non-significant trend toward faster resolution of hyponatremia. The use of fluid restriction and diuretics should be de-emphasized in the treatment of post-transsphenoidal hyponatremia, as they have not been shown to significantly alter the time-course to the restoration of sodium balance.

Delayed postoperative hyponatremia after transsphenoidal surgery: prevalence and associated factors

Object

Transient delayed postoperative hyponatremia (DPH) after transsphenoidal surgery (TSS) is common and can have potentially devastating consequences. However, the true prevalence of transient symptomatic and asymptomatic DPH has not been studied in a large patient cohort with close and accurate follow-up.

Methods

A retrospective analysis of a single-institution prospective database was conducted; all patients undergoing TSS for lesions involving the pituitary gland were followed up in a multidisciplinary neuroendocrine clinic, and demographic, imaging, and clinical data were prospectively collected. Patients were examined preoperatively and followed up postoperatively in a standardized fashion, and their postoperative sodium levels were measured at Weeks 1 and 2 postoperatively. Levels of hyponatremia were rated as mild (serum sodium concentration 130–134 mEq/L), moderate (125–129 mEq/L), or severe (< 125 mEq/L). Routine clinical questionnaires were administered at all postoperative office visits. Postoperative hyponatremia was analyzed for correlations with demographic and clinical features and with immediate postoperative physiological characteristics.

Results

Over a 4-year interval, 373 procedures were performed in 339 patients who underwent TSS for sellar and parasellar lesions involving the pituitary gland. The mean (± SD) age of patients was 48 ± 18 years; 61.3% of the patients were female and 46.1% were obese (defined as a body mass index [BMI] ≥ 30). The overall prevalence of DPH within the first 30 days postoperatively was 15.0%; 7.2% of the patients had mild, 3.8% moderate, and 3.8% severe hyponatremia. The incidence of symptomatic hyponatremia requiring hospitalization was 6.4%. The Fisher exact test detected a statistically significant association of DPH with female sex (p = 0.027) and a low BMI (p = 0.001). Spearman rank correlation detected a statistically significant association between BMI and nadir serum sodium concentration (r = 0.158, p = 0.002) and an inverse association for age (r = −0.113, p = 0.031). Multivariate analyses revealed a positive correlation between postoperative hyponatremia and a low BMI and a trend toward association with age; there were no associations between other preoperative demographic or perioperative risk factors, including immediate postoperative alterations in serum sodium concentration. Patients were treated with standardized protocols for hyponatremia, and DPH was not associated with permanent morbidity or mortality.

Conclusions

Delayed postoperative hyponatremia was a common result of TSS; a low BMI was the only clear predictor of which patients will develop DPH. Alterations in immediate postoperative sodium levels did not predict DPH. Therefore, an appropriate index of suspicion and close postoperative monitoring of serum sodium concentration should be maintained for these patients, and an appropriate treatment should be undertaken when hyponatremia is identified.

Hyponatremia after transsphenoidal surgery for hypothalamo-pituitary tumors

Transient diabetes insipidus is a well-known complication after transsphenoidal surgery (TSS). On the other hand, transient hyponatremia has been reported as being a delayed complication of TSS. Transient hyponatremia has been attributed to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), but the details of hyponatremia have not been clarified. In the present study, we retrospectively reviewed 110 consecutive patients (39 males and 71 females, age 9-80 years) operated on transsphenoidally for pituitary and hypothalamic tumors. We investigated the frequency, time of onset, duration of hyponatremia after TSS, and analyzed possible factors associated with it. A postoperative sodium concentration <135 mEq/l was observed in 29 (26%) patients. Five patients were excluded from this study because their hyponatremia could be due to either overdose of desmopressin or SIADH for meningitis. Therefore, we investigated 24 (22%) patients with hyponatremia in this study. The sodium levels in the patients with hyponatremia ranged from 110 to 134, with a mean of 126.2 +/- 5.3 mEq/l. Hyponatremia was observed on average on postoperative day 9.5 +/- 2.4, the serum sodium levels normalized within 3.8 +/- 1.7 days. Hyponatremia occurred in patients with non-functioning pituitary adenoma (26%, 11/42), Rathke's cleft cyst (29%, 5/17), prolactinoma (31%, 4/13) and acromegaly (15%, 4/27). 18 patients (75%, 6/24) who developed hyponatremia had macrotumor (>10 mm), and 6 patients (25%, 6/24) had microtumor. The plasma arginine vasopressin (AVP) levels in the patients with hyponatremia ranged from 0.21 to 2.1, with a mean of 0.79 +/- 0.46 pg/ml, and the levels were inversely correlated with plasma osmolality (r = -0.80, p = 0.002). The urine to plasma osmolality ratios were >1. All the patients received appropriate hormonal replacement, including hydrocortisone. These data showed that postoperative hyponatremia after TSS was not rare, and the hyponatremia was mainly associated with SIADH. As the hyponatremia could be a life-threatening complication, all patients should be screened for serum electrolytes after TSS.

Hyponatremia in the neurosurgical patient: diagnosis and management

Hyponatremia is frequently encountered in patients who have undergone neurosurgery for intracranial processes. Making an accurate diagnosis between the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt wasting (CSW) in patients in whom hyponatremia develops is important because treatment differs greatly between the conditions. The SIADH is a volume-expanded condition, whereas CSW is a volume-contracted state that involves renal loss of sodium. Treatment for patients with SIADH is fluid restriction and treatment for patients with CSW is generally salt and water replacement. In this review, the authors discuss the differential diagnosis of hyponatremia, distinguish SIADH from CSW, and highlight the diagnosis and management of hyponatremia, which is commonly encountered in patients who have undergone neurosurgery, specifically those with traumatic brain injury, aneurysmal subarachnoid hemorrhage, recent transsphenoidal surgery for pituitary tumors, and postoperative cranial vault reconstruction for craniosynostosis.

Distúrbios na secreção e ação do hormônio antidiurético

A manutenção da constância da osmolalidade plasmática e do equilíbrio hidroeletrolítico deve-se à regulação do volume extracelular e da natremia, através da integração entre as ações do hormônio antidiurético (ADH), o sistema renina-angiotensina-aldosterona (SRAA) e o mecanismo da sede. Distúrbios na síntese, secreção ou ação do ADH podem resultar em síndromes poliúricas, em que ocorre excreção aumentada de urina hipotônica, resultante da ingestão excessiva de água, secreção ou ação inadequadas do ADH ou alterações nos canais de água da aquaporina-2 (AQP2). A hiponatremia pode ocorrer por depleção de sal, mecanismos dilucionais ou metabólicos, além de ser uma freqüente ocorrência após a cirurgia hipofisária, tendo sido descrita em 9 a 35% de pacientes operados. A causa pode ser devida a uma lesão transitória ou definitiva da hipófise posterior, a síndrome de secreção inapropriada do hormônio antidiurético (SIADH) ou, mais freqüentemente, a síndrome cerebral perdedora de sal (SCPS). A apresentação clínica de ambas as síndromes é similar e o diagnóstico diferencial pode apresentar dificuldades. A determinação do estado volêmico é essencial para o diagnóstico, já que os pacientes portadores de SIADH caracterizam-se por serem euvolêmicos ou hipervolêmicos, enquanto aqueles com a SCPS são hipovolêmicos. Os critérios para o diagnóstico incluem parâmetros clínicos, determinação da osmolalidade plasmática e urinária e os testes de restrição hídrica, sobrecarga hipertônica e o da furosemida, importante na discriminação entre SIADH e SCPS. O tratamento das síndromes poliúricas depende da etiologia e inclui o uso de análogos do ADH, diuréticos, ou outras drogas tais como clorpropramida, clofibrato, corticóides e carbamazepina. O tratamento da SIADH necessita de restrição de líqüidos e/ou furosemida para diminuir o volume de água extracelular. O tratamento da SCPS, ao contrário, implica em reposição de volume com fornecimento de suplementação de sódio e líqüidos, sendo que a fludrocortisona pode ser uma boa alternativa terapêutica.

Prevalence, predictors and patterns of postoperative polyuria and hyponatraemia in the immediate course after transsphenoidal surgery for pituitary adenomas

OBJECTIVE

Disturbances of osmoregulation, leading to diabetes insipidus and hyponatraemia are well known complications after surgery in the sella region. This study was performed to examine the prevalence and predictors of polyuria and hyponatraemia after a complete and selective removal of pituitary adenomas was attempted via the transnasal-transsphenoidal approach.

DESIGN

1571 patients with pituitary adenomas (238 Cushing's disease, 405 acromegaly, 534 hormonally inactive adenomas, 358 prolactinoma, 23 Nelson's syndrome, and 13 thyrotropinoma) were daily examined within a 10-day postoperative inpatient observation period. Prevalence of patterns of polyuria (> 2500 ml) and oliguria/hyponatraemia (< 132 mmol/l) were surveyed as well as predictors of postoperative morbidity.

RESULTS

487 patients (31%) developed immediate postoperative hypotonic polyuria, 161 patients (10%) showed prolonged polyuria and 37 patients (2.4%) delayed hyponatraemia. A biphasic (polyuria-hyponatraemia) and triphasic (polyuria-hyponatraemia-polyuria) pattern was seen in 53 (3.4%) and 18 (1.1%) patients, respectively. Forty-one patients (2.6%) displayed immediate postoperative (day 1) hyponatraemia. Altogether, 8.4% of patients developed hyponatraemia at some time up to the 10th day postoperative, with symptomatic hyponatraemia in 32 patients (2.1%). Risk analysis showed that patients with Cushing's disease had a fourfold higher risk of polyuria than patients with acromegaly and a 2.8-fold higher risk for postoperative hyponatraemia. Younger age, male sex, and intrasellar expansion were associated with a higher risk of hypotonic polyuria, but this was not considered clinically relevant.

CONCLUSIONS

The analysis illustrates that disturbances in osmoregulation resulting in polyuria and pertubations of serum sodium concentration are of very high prevalence and need observation even after selective transsphenoidal surgery for pituitary adenomas, especially in patients with Cushing's disease.

Complications of transsphenoidal surgery: results of a national survey, review of the literature, and personal experience

OBJECTIVE

The primary objectives of this report were, first, to determine the number and incidence of complications of transsphenoidal surgery performed by a cross-section of neurosurgeons in the United States and, second, to ascertain the influence of the surgeon's experience with the procedure on the occurrence of these complications. The secondary objective was to review complications of transsphenoidal surgery from the standpoint of their causation, treatment, and prevention.

METHODS

Questionnaires regarding 14 specific complications of transsphenoidal surgery were mailed to 3172 neurosurgeons. The data reported were analyzed from the 958 respondents (82%) who reported performing the operation. The neurosurgeons surveyed were asked to estimate the number of transsphenoidal operations performed, to identify any complications observed, and to estimate the percentage of operations that had resulted in any of the 14 specific complications. The 958 respondents were placed into three experience groups, based on the number of transsphenoidal operations performed. The data were analyzed by using chi 2 tests and Spearman correlation coefficients. The secondary objectives were met through a detailed review of the literature, in light of our experience.

RESULTS

Of the respondents, 87.3% reported having performed < 200 operations and 9.7% reported 200 to 500 previous operations. The remaining 3% reported more than 500 previous operations. More extensive previous experience with transsphenoidal surgery was associated with a greater likelihood of having witnessed each specific complication. The mean operative mortality rate for all three groups was 0.9%. Anterior pituitary insufficiency (19.4%) and diabetes insipidus (17.8%) were complications with the highest incidence of occurrence. The overall incidence of cerebrospinal fluid fistulas was 3.9%. Other significant complications, such as carotid artery injuries, hypothalamic injuries, loss of vision, and meningitis, occurred with incidence rates between 1 and 2%. An inverse relationship was found between the experience group and the likelihood of complications, as indicated by significant negative Spearman correlation coefficients for all but 2 of the 14 complications listed in the survey (P < 0.05). Thus, increased experience with transsphenoidal surgery seems to be associated with a decreased percentage of operations resulting in complications. Some caution should be exercised in interpreting these data, because they are based on the respondents' estimates.

CONCLUSION

Transsphenoidal surgery seems to be a reasonably safe procedure, with a mortality rate of less than 1%. However, a significant number of complications do occur. The incidence of these complications seems to be higher, with statistical significance, in the hands of less experienced surgeons. The learning curve seems to be relatively shallow, because a statistically significantly decreased incidence of morbidity and death could be documented after 200 and even 500 transsphenoidal operations. Better understanding of the indications for transsphenoidal surgery and improved familiarity with the regional anatomy should further lower the incidence of death and morbidity resulting from this procedure in the hands of all neurosurgeons.

Delayed onset of hyponatremia after transsphenoidal surgery for pituitary adenomas

Hyponatremia is rarely reported as a delayed complication of transsphenoidal resection of pituitary adenoma. Usually attributed to the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), hyponatremia causes nonspecific symptoms, often after hospital discharge. To clarify the frequency, presentation, and outcome of this poorly understood complication, we reviewed our database of 2297 patients who underwent transsphenoidal pituitary surgery between February 1971 and June 1993. Of 53 patients (2.3%) treated for symptomatic hyponatremia, 11 were excluded (2 received arginine vasopressin within 24 hours, 1 had untreated hypothyroidism, 4 had untreated adrenal insufficiency, and 4 had incomplete records). The remaining 42 patients (1.8%), 11 men and 31 women aged 21 to 79 years, presented 4 to 13 days (mean, 8 d) postoperatively with nausea and vomiting (20 patients), headache (18 patients), malaise (12 patients), dizziness (4 patients), anorexia (2 patients), and seizures (1 patient). Hyponatremia was unrelated to sex, age, adenoma type, tumor size, or glucocorticoid tapering. Although the clinical picture in our patients is consistent with SIADH, this was not supported by the antidiuretic hormone levels, which were normal or low-normal in the two patients in whom they were measured, suggesting the possibility that low serum sodium may not reflect SIADH. In all patients, hyponatremia resolved within 6 days (mean, 2 d); treatment consisted of salt replacement and mild fluid restriction in 37 patients and fluid restriction only in 4 (treatment unknown in 1). Delayed hyponatremia after transsphenoidal resection of pituitary adenoma is not as rare as previously thought, nor is it necessarily associated with SIADH or with hypoadrenalism during glucocorticoid tapering.(ABSTRACT TRUNCATED AT 250 WORDS)

Delayed hyponatremia after transsphenoidal surgery for pituitary adenoma. Report of nine cases

Hyponatremia, usually attributed to the syndrome of inappropriate secretion of antidiuretic hormone, typically occurs in a delayed fashion following transsphenoidal removal of a pituitary adenoma. In a series of 99 consecutive patients who underwent transsphenoidal surgery for pituitary adenoma, nine patients developed delayed hyponatremia, seven of whom were symptomatic. Of these seven patients, four had been discharged from the hospital and required readmission on postoperative Day 7 to 9. In the nine patients who developed hyponatremia, on the average, serum sodium levels began to fall on Day 4 and reached a nadir on Day 7 (mean serum sodium nadir 123 mmol/L). The development of delayed hyponatremia was associated with the presence of a macroadenoma in eight of the nine patients. Seven of the nine patients had serum sodium levels less than 130 mmol/L and required treatment. One patient was treated with fluid restriction alone and six were treated with both fluid restriction and intravenous urea therapy. Twenty-four and 48 hours after urea administration, serum sodium levels rose by an average of 6 and 10 mmol/L, respectively, and at discharge, levels averaged 136 mmol/L. Intravenous administration of urea provides a rapid yet safe means of correcting symptomatic hyponatremia when fluid restriction alone is inadequate. In this article, the authors discuss the pathogenesis of delayed hyponatremia.

The triple-phase response--problems of water balance after pituitary surgery

A 29-year-old woman presenting with persistent headache and oligomenorrhoea was found to have a pituitary adenoma which was treated surgically. Postoperatively she developed diabetes insipidus which resolved on treatment with desmopressin acetate. She represented 11 days post surgery with nausea and vomiting and inappropriate antidiuresis was diagnosed in an infectious diseases unit. On re-admission to our unit cranial diabetes insipidus was confirmed by water deprivation. This case demonstrates the need for careful monitoring of patients after pituitary and suprasellar surgery or head injury.

Polyuric states in man

This chapter reviews the pathophysiological basis for the mechanisms of polyuria and discusses the causes in detail. A small proportion of patients with CDI are of the idiopathic type, with the majority of causes due to trans-spenoidal surgery, head injury following road traffic accidents, and an autoimmune variant. Indirect methods of investigating polyuria are inaccurate in a significant proportion of cases, and the incorporation of measurements of plasma AVP into a water-deprivation test or hypertonic saline infusion can improve diagnostic accuracy. Non-osmotic tests of AVP secretion are of no value in the differential diagnosis of polyuria. Most patients with CDI can maintain water homeostasis with adequate fluid intake, but desmopressin is a convenient, effective and safe therapy which is recommended on both social and medical grounds. Treatment of NDI remains problematic, as neither thiazide diuretics or indomethacin can completely abolish polyuria, and fluid intake remains of primary importance.

Dissociation between activation of the hypothalamo-hypophyseal antidiuretic system and the type of diuresis during acute intracranial hypertension. Experimental observation

Acute cerebral compression by a supra- and infratentorial balloon produced a triphasic pattern of diuresis. The 1st phase was characterized by polyuria associated with five fold increase of plasma (p) antidiuretic hormone (ADH) concentration, decreased urine osmolality in spite of natriuresis and blood pressure elevation. The 2nd phase was characterized by oliguria, a decrease of pADH and reduced urine Na+ concentration, whereas urine osmolality transiently increased. At this stage there was respiratory arrest and fall of blood pressure. The final stage was diabetes insipidus (DI), when EEG activity had disappeared. An increase of serum osmolality mainly occurred during the last DI phase. Serum Na+ concentration fluctuated slightly during the whole period of diuresis. These results present evidence, that the diuresis pattern reflects the hypothalamo-hypophyseal antidiuretic system (HHAS) reaction to acute intracranial pressure (ICP) increase with the vegetative symptoms of cerebral shock.