Serum OPG/TRAIL ratio predicts the presence of cardiovascular disease in people with type 2 diabetes mellitus

AIMS

Cardiovascular disease (CVD) is the leading cause of mortality in type 2 diabetes mellitus (T2DM). Epidemiological studies suggest serum Osteoprotegrin (OPG)/Tumour-necrosis-factor-related-apoptosis-inducing- ligand (TRAIL) ratio may be a useful marker of cardiovascular risk. This study aimed to compare serum levels of TRAIL, OPG and OPG/TRAIL ratio in people with T2DM, with and without a history of CVD, and controls; and to determine which of these indices, if any, predict cardiovascular risk.

METHODS

In this single centre observational study of 133 participants, people with T2DM, with and without a history of a cardiovascular event in the last 5 years, were recruited along with a control cohort without T2DM or CVD. Demographic information and anthropometric measurements were recorded. Blood samples were taken and OPG and TRAIL were measured using ELISA.

RESULTS

People with T2DM and CVD had higher OPG/TRAIL ratios compared to controls or those with a new diagnosis of T2DM. After adjustment for potential confounding factors, OPG/TRAIL ratio was significantly associated with the presence of CVD in people with T2DM and an OPG/TRAIL ratio cut-off > 38.6 predicted the presence of CVD in this cohort with a sensitivity of 80% and specificity of 82%.

CONCLUSION

This study suggests that OPG/TRAIL ratio may have a role as a biomarker of CVD in people with T2DM.

Hyponatraemia and the syndrome of inappropriate antidiuresis (SIAD) in cancer

Hyponatraemia is a common electrolyte abnormality seen in a wide range of oncological and haematological malignancies and confers poor performance status, prolonged hospital admission and reduced overall survival, in patients with cancer. Syndrome of inappropriate antidiuresis (SIAD) is the commonest cause of hyponatraemia in malignancy and is characterised by clinical euvolaemia, low plasma osmolality and concentrated urine, with normal renal, adrenal and thyroid function. Causes of SIAD include ectopic production of vasopressin (AVP) from an underlying tumour, cancer treatments, nausea and pain. Cortisol deficiency is an important differential in the assessment of hyponatraemia, as it has an identical biochemical pattern to SIAD and is easily treatable. This is particularly relevant with the increasing use of immune checkpoint inhibitors, which can cause hypophysitis and adrenalitis, leading to cortisol deficiency. Guidelines on the management of acute, symptomatic hyponatraemia recommend 100 mL bolus of 3% saline with careful monitoring of the serum sodium to prevent overcorrection. In cases of chronic hyponatraemia, fluid restriction is recommended as first-line treatment; however, this is frequently not feasible in patients with cancer and has been shown to have limited efficacy. Vasopressin-2 receptor antagonists (vaptans) may be preferable, as they effectively increase sodium levels in SIAD and do not require fluid restriction. Active management of hyponatraemia is increasingly recognised as an important component of oncological management; correction of hyponatraemia is associated with shorter hospital stay and prolonged survival. The awareness of the impact of hyponatraemia and the positive benefits of active restoration of normonatraemia remain challenging in oncology.

US Food and Drug Administration regulatory pesticide residue monitoring of human foods: 2009-2017

Pesticides such as insecticides, fungicides, and herbicides can protect crops from insects, fungi, weeds, and other pests but must be applied following label instructions so that the pesticide residues in human and animal foods do not exceed maximum residue limits (MRLs, known in the US as pesticide tolerances). The US Food and Drug Administration (FDA) collects and tests foods for pesticide residues to enforce compliance with tolerances and publishes annual reports on pesticide testing results. In this study, results for over 56,000 human food samples collected and analysed under the FDA pesticide residue monitoring programme between fiscal years (FY) 2009 to 2017 were reviewed to identify trends not apparent in annual reports. The overwhelming majority of these samples, 98.0% of domestic and 90.9% of import human foods, were compliant with federal standards. Although herbicides may be more widely used, the 10 most frequently detected residues were insecticides and fungicides. On a yearly basis, the violation rate for imported samples is 3-5 times higher than the rate for domestic samples. The import violation rate increased over time, as did the number of residues detected. Targeted sampling of foods with higher commodity-specific violation rates appears to be a major contributor to the increased violation rate. Mismatches between US tolerances and international MRLs can lead to violations; this was especially marked for rice. Overall, the majority of violations are due to residues of pesticides not authorised for use in the US (lack of tolerances). While DDT continues to persist in the environment and was found in 2.2% of domestic samples and 0.6% of imported samples, 42.3% of DDT-positive samples were below the limit of quantitation. The trends and analyses identified in this paper may help FDA plan future sampling and continue to protect the food supply.

Prevalence of Cronobacter spp. and Salmonella in Milk Powder Manufacturing Facilities in the United States

ABSTRACT

The U.S. Food and Drug Administration (FDA) conducted a sampling assignment in 2014 to ascertain the prevalence of Cronobacter spp. and Salmonella in the processing environment of facilities manufacturing milk powder. Cronobacter was detected in the environment of 38 (69%) of 55 facilities. The average prevalence of Cronobacter in 5,671 subsamples (i.e., swabs and sponges from different facility locations) was 4.4%. In the 38 facilities where Cronobacter was detected, the average prevalence of positive environmental subsamples was 6.25%. In 20 facilities where zone information of the sampling location was complete, Cronobacter was most frequently detected in zone 4, followed by zone 3, then zone 2, with zone 1 yielding the lowest percentage of positive samples. The prevalence of Cronobacter across the zones was statistically different (P < 0.05). There was no significant association between product type (i.e., lactose, whey products, buttermilk powder, and nonfat dried milk) and prevalence of Cronobacter in the facility. Salmonella was detected in the environment of three (5.5%) of the 55 facilities; all three facilities produced dried whey product. The overall prevalence of Salmonella in 5,714 subsamples was 0.16%. In facilities in which Salmonella was detected, the average prevalence was 2.5%. Salmonella was most frequently detected in zone 4, followed by zone 3. Salmonella was not detected in zone 1 or zone 2. The disparity between Salmonella and Cronobacter prevalence indicates that additional measures may be required to reduce or eliminate Cronobacter from the processing environment.

HIGHLIGHTS

109 Hyponatraemia in Older Patients is Often Untreated, Despite Greater Mortality Burden; Results of A Prospective Cohort Study

Introduction

Hyponatraemia is associated with increased morbidity and mortality, and is commoner in elderly patients. The aetiology and outcomes of hyponatraemia in the elderly has not been defined in prospective studies.

Methods

A single-centre 9 month prospective observational study of hyponatraemic (HN) patients (&lt;/= 130 mmol/L) was performed. Clinical outcomes in patients ≥65 years (Elderly patients, EP) and those &lt;65 years (Young Patients, YP) were analysed, and compared with age-matched eunatremic controls, Analysis was performed using Graphpad-Prism 7.

Results

1321 consecutive admissions with hyponatraemia (67% EP, median age of EP 77 (65–98) years) and 1122 eunatremic controls (63% EP, median age of EP 77 (65–99) years) were analysed.

Median nadir plasma sodium was similar in both groups with HN, 128 (107–130) mmol/L EP vs 128(110–130) mmol/L YP (p = 0.62). EP hyponatraemic patients were more likely to have hypovolaemic hyponatraemia (34%) compared with YP with hyponatraemia (28%, p = 0.03). Diuretic-induced hyponatraemia was twice as common in EP (8%) compared with YP (4%, p = 0.01). Malignancy-induced SIAD occurred with similar frequency in both groups (7% in EP SIAD vs 8% in YP SIAD, p = 0.65). Respiratory disease was causative in 10% cases of EP SIAD, compared with 4% in YP SIAD, p = 0.0004.

Hyponatraemia was corrected in 53% of EP, compared with 64% of YP, p = 0.0001. Length of stay and re-admissions rates were similar across hyponatraemia age groups. EP with HN were 2.4 times more likely to die in hospital, compared with eunatremic age-matched controls, (OR 2.4, 95% CI 1.6–3.7, p &lt; 0.0001).

Conclusions

The causation of hyponatraemia is different in elderly patients. Hyponatraemia in EP is often uncorrected, despite increased mortality compared with eunatremic age-matched controls.

Bortezomib-induced hyponatremia: tolvaptan therapy permits continuation of lenalidomide, bortezomib and dexamethasone therapy in relapsed myeloma

The development of hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion (SIADH) is well recognised in multiple myeloma (MM). SIADH, due to either MM or Bortezomib can be hazardous as severe hyponatremia may develop if large volumes of hypotonic intravenous fluid are used as an adjunct to chemotherapy. We report a case of Bortezomib-induced SIADH, in whom the use of tolvaptan, a vasopressin receptor-2 antagonist, permitted the continuation of triple combination anti-MM therapy with lenalidomide, Bortezomib and dexamethasone (RVD) in a female with aggressive disease, without the development of hyponatremia. Our patient had a rapid relapse, in which the use of Bortezomib as part of an RVD regimen was life-saving. The use of tolvaptan allowed continuation of therapy that is usually halted in other similarly reported cases. This case highlights the possible use of vaptans, which allows an aquaresis to occur by blocking the antidiuretic effects of vasopressin, as a treatment for Bortezomib-induced hyponatremia.

Endocrinopathies and renal outcomes in lithium therapy: impact of lithium toxicity

BACKGROUND

Lithium is the mainstay of treatment for bipolar disorder, mania and an augmentation therapy in patients with treatment resistant depression. It has a narrow therapeutic index, with recognized adverse multi-system and endocrine side effects.

AIM

To assess the impact of lithium therapy, in particular lithium toxicity, on the development of endocrine and renal disorders in a cohort of patients in a single tertiary referral centre in Ireland.

STUDY DESIGN

A retrospective analysis was performed of the prevalence of lithium toxicity and renal, thyroid and parathyroid dysfunction in our study population.

METHODS

We collected laboratory data from the Clinical Chemistry department of the Adelaide and Meath Hospital incorporating the National Children's Hospital (AMNCH), Dublin, Ireland. Our study population included all patients who had at least one serum lithium measurement from January 1st 2000 to December 31st 2014 inclusive.

RESULTS

A total of 580 patients were included in the study. Among our study group, 70 patients (12.1%) had 1 toxic lithium measurement (lithium level >1.2 mmol/l). 27.8% (n > 161) of patients developed stage 3 Chronic kidney Disease (CKD) or higher, which was commoner in those patients who developed toxic lithium levels (P < 0.0001) and in those who developed hypernatraemia (P > 0.0001). 16.2% of patients (n > 94) had one serum sodium >145 mmol/l during follow up. 60 patients(10.3%) had a TSH >10 mU/l, while complete suppression of TSH (<0.05 mU/l) was observed in 22 patients (3.8%) during follow-up. 4% (n > 37) of the study population had ≥1 serum corrected calcium level > 2.55 mmol/l, and 4 patients had biochemical confirmation of primary hyperparathyroidism but PTH levels were only performed in 2.8% (n > 16) of the studypopulation.

CONCLUSION

Stage 3 CKD is common in patients receiving lithium therapy. Lithium toxicity is associated with CKD and hypernatraemia. Thyroid dysfunction and hypercalcaemia are common in patients receiving lithium therapy. Patients receiving lithium therapy require surveillance of renal, thyroid and bone biochemistry.

The incidence of anterior pituitary hormone deficiencies in patients with microprolactinoma and idiopathic hyperprolactinaemia

INTRODUCTION

Patients with microprolactinoma and idiopathic hyperprolactinaemia are not generally considered to be at risk of hypopituitarism and are therefore not routinely screened for this abnormality. In our clinical practice, we have observed a number of patients with nonmacroadenomatous hyperprolactinaemia to have anterior pituitary hormone deficits.

AIMS

We aimed to establish the frequency and clinical significance of anterior pituitary hormone deficiencies, comparing patients with radiologically proven microprolactinomas and patients with idiopathic hyperprolactinaemia.

STUDY DESIGN

We retrospectively examined the casenotes of 206 patients with hyperprolactinaemia from our centre. Patients who did not fit the profile of surgically naïve microprolactinoma or idiopathic hyperprolactinaemia or who had incomplete data were excluded, resulting in a study group of 56 patients.

RESULTS

A total of 35 patients with MRI evidence of microprolactinoma were identified, three (8.57%) of whom had one or more anterior pituitary hormone deficiencies. A total of 21 patients with MRI-negative idiopathic hyperprolactinaemia were identified, nine (42%) of whom had one or more anterior pituitary hormone deficiencies (P<.01). Only one patient in the MRI-positive group had deficiency that required hormone replacement, in contrast six patients in the MRI-negative group had deficiencies that were of clinical significance and which required hormone replacement.

SUMMARY

This study shows a clinically significant incidence of anterior pituitary hormone deficiency in patients with idiopathic hyperprolactinaemia. The authors recommend that dynamic pituitary assessment should be considered routinely in this patient group. A prospective study would be required to assess the underlying cause for these abnormalities, as they suggest a nontumour pan-pituitary process.

Predictors of failure to respond to fluid restriction in SIAD in clinical practice; time to re-evaluate clinical guidelines?

BACKGROUND

Fluid restriction is recommended as first line therapy for Syndrome of Inappropriate Antidiuresis (SIAD), despite of lack of good evidence base to support its use, and poor efficacy in clinical practice and in the literature.

AIM

We set out to determine how many patients with well-defined SIAD had pre-treatment criteria which would predict failure to fluid restriction.

DESIGN AND METHODS

This was a consecutive, prospective evaluation of 183 patients with a diagnosis of SIAD in two different hospitals. Full ascertainment of the diagnostic criteria for SIAD was obtained in all patients.

RESULTS

About 47% of patients had a urine volume <1500 ml in 24 h, 41% had initial urine osmolality > 500 mOsm/kg, 26% a Furst-equation ratio > 1. About 59% had one criterion predicting failure to respond to fluid restriction, 37% two criteria, and 3% three criteria.

CONCLUSIONS

Our data suggest that up to 60% of patients with SIAD had criteria which recent clinical guidelines suggest would predict nonresponse to fluid restriction. This may explain why the recommended first line therapy for SIAD has been shown to be ineffective.

Pituitary tuberculoma: a rare cause of sellar mass

INTRODUCTION

Pituitary tuberculosis is an uncommon cause of sellar mass [1]; the estimated prevalence worldwide is not known, and there have been no reports of the condition occurring in Ireland. Tuberculosis of the pituitary gland may present as a sellar mass or with symptoms of hypopituitarism.

CASE PRESENTATION

A 41-year-old woman, with a short prodromal history without endocrine symptoms, was found to have pituitary tuberculosis after the demonstration of a sellar mass on MRI, and lumbar puncture findings consistent with lymphocytic meningitis.

CONCLUSION

To our knowledge, this is the first published case of pituitary tuberculoma in Ireland.

Diabetes in Patients With Acromegaly

Acromegaly is a clinical syndrome which results from growth hormone excess. Uncontrolled acromegaly is associated with cardiovascular mortality, due to an excess of risk factors including diabetes mellitus, hypertension and cardiomegaly. Diabetes mellitus is a frequent complication of acromegaly with a prevalence of 12-37%. This review will provide an overview of a number of aspects of diabetes mellitus and glucose intolerance in acromegaly including the following: 1. Epidemiology and pathophysiology of abnormalities of glucose homeostasis 2. The impact of different management options for acromegaly on glucose homeostasis 3. The management options for diabetes mellitus in patients with acromegaly RECENT FINDINGS: Growth hormone and IGF-1 have complex effects on glucose metabolism. Insulin resistance, hyperinsulinaemia and increased gluconeogenesis combine to produce a metabolic milieu which leads to the development of diabetes in acromegaly. Treatment of acromegaly should ameliorate abnormalities of glucose metabolism, due to reversal of insulin resistance and a reduction in gluconeogenesis. Recent advances in medical therapy of acromegaly have varying impacts on glucose homeostasis. These adverse effects influence management choices in patients with acromegaly who also have diabetes mellitus or glucose intolerance. The underlying mechanisms of disorders of glucose metabolism in patients with acromegaly are complex. The aim of treatment of acromegaly is normalisation of GH/IGF-1 with reduction of co-morbidities. The choice of therapy for acromegaly should consider the impact of therapy on several factors including glucose metabolism.

SIAD: practical recommendations for diagnosis and management

Hyponatremia is the commonest electrolyte disturbance encountered in hospitalized patients, and the syndrome of inappropriate antidiuresis (SIAD) is the most frequent underlying disorder. There is a well-recognized relationship between hyponatremia and increased morbidity and mortality. Therefore, to provide appropriate treatment is critical to improve the clinical outcome related to SIAD-hyponatremia. There have been important advances in the treatment of SIAD over the last decade, leading to the publication of several clinical guidelines. In particular, the introduction of the vasopressin-2 receptor antagonists provides a potent pharmacological tool to target the underlying pathophysiology of SIAD. The evidence base recommendations of the available therapies for SIAD are discussed in this study. Fluid restriction is considered the first-line therapy by the recent published guidelines, but it is certainly ineffective or unfeasible in many patients with SIAD. We discuss a number of relevant points to the use of fluid restriction in this study, including the lack of good evidence-based recommendations to support its use. Conversely, the clinical efficacy of oral tolvaptan in SIAD supported by good quality randomized, placebo controlled, clinical trials. However, the cost of the therapy and the need for long-term safety data may limit its widespread use. Finally, new recommendations for the management of acute hyponatremia with a focus on the use of bolus therapy with 3 % hypertonic sodium chloride are described in this study.

Heterogenous patterns of recovery of thirst in adult patients with adipsic diabetes insipidus

BACKGROUND

The natural history of adipsic diabetes insipidus (ADI) is not well described, and reports of recovery of thirst are rare.

DESIGN AND METHODS

Case histories presentation. ADI was identified by demonstrating absent thirst and arginine vasopressin (AVP) responses to hypertonic saline infusion.

RESULTS

Twelve patients with ADI were identified (craniopharyngioma 5, anterior communicating artery aneurysm (ACOM) repair 4, congenital 1, neurosarcoidosis 1, prolactinoma 1). Three patients died. Six patients had permanent ADI. Three patients had recovery of thirst, with a heterogenous pattern of recovery. In the first case, ADI had developed after clipping of an ACOM aneurysm. Ten years after surgery; he sensed the return of thirst; repeated hypertonic saline infusion showed recovery of thirst and AVP secretion. In the second case, a 41-year-old female with an intrasellar craniopharyngioma developed post-operative ADI with persistent hypernatremia. Two years post-operatively, she complained of thirst, and hypertonic saline infusion showed normalization of thirst but absent AVP responses, confirming recovery of thirst, but with persistent diabetes insipidus (DI). In the third case, a 29-year-old Caucasian had craniotomy and radiotherapy for craniopharyngioma and developed ADI post-operatively. Eight years post-op, she presented with thirst, seizures and pNa of 112 mmol/l. Hypertonic saline infusion showed persistent DI but thirst responses typical of compulsive water drinking; she has had recurrent hyponatraemia since then.

CONCLUSIONS

We report that 3/12 patients with ADI recovered thirst after longstanding adipsia with heterogenous pattern of recovery. Both the mortality of 25% and the recovery rate of 25% should be considered when planning long-term surveillance.

The syndrome of inappropriate antidiuresis (SIAD)

Hyponatraemia is the commonest electrolyte disturbance encountered in clinical practice and the syndrome of inappropriate antidiuresis (SIADH) is the most frequent underlying disorder. There is a well-recognized relationship between hyponatraemia and increased morbidity and mortality, though it is unknown whether SIADH confers the same mortality as other causes of hyponatraemia. SIADH is the biochemical manifestation of a wide variety of diseases, and the pathophysiology of SIADH is sometimes multiple. There have been significant advances in the treatment of SIADH over the last 10 years, in particular since the introduction of the vasopressin-2 receptor antagonists, which provide a potent, disease-specific tool which targets the underlying pathophysiology of SIADH. The mechanisms and the evidence base recommendations of the available therapies for SIADH are discussed in this article. The various guidelines and recommendations for treatment of hyponatraemia all emphasise that fluid restriction is first line therapy for SIADH, but we feel that it is ineffective or unfeasible in many patients. A number of key points relevant to the use of fluid restriction are presented in the manuscript. The clinical efficacy of tolvaptan in SIADH supported by good quality randomized, placebo controlled, clinical trials. However, the cost of the therapy and the need for long term safety data may limit its widespread use. Finally, new recommendations for the management of acute hyponatraemia, with a focus on the use of bolus therapy with 3% hypertonic sodium chloride is described.

Cervicomedullary tumors in children

OBJECT

Cervicomedullary tumors (CMTs) represent a heterogeneous group of intrinsic neoplasms that are typically low grade and generally carry a good prognosis. This single-institution study was undertaken to document the outcomes and current treatment philosophy for these challenging neoplasms.

METHODS

The charts of all pediatric patients with CMTs who received treatment at St. Jude Children's Research Hospital between January 1988 and May 2013 were retrospectively reviewed. Demographic, surgical, clinical, radiological, pathological, and survival data were collected. Treatment-free survival and overall survival were estimated, and predictors of recurrence were analyzed.

RESULTS

Thirty-one children (16 boys, 15 girls) with at least 12 months of follow-up data were identified. The median age at diagnosis was 6 years (range 7 months-17 years) and the median follow-up was 4.3 years. Low-grade tumors (Grade I or II) were present in 26 (84%) patients. Thirty patients underwent either a biopsy alone or resection, with the majority of patients undergoing biopsy only (n = 12, 39%) or subtotal resection (n = 14, 45%). Only 4 patients were treated solely with resection; 21 patients received radiotherapy alone or in combination with other treatments. Recurrent tumor developed in 14 children (45%) and 4 died as a result of their malignancy. A high-grade pathological type was the only independent variable that predicted recurrence. The 5- and 10-year treatment-free survival estimates are 64.7% and 45.3%, respectively. The 5- and 10-year overall survival estimate is 86.7%.

CONCLUSIONS

Children with CMTs typically have low-grade neoplasms and consequently long-term survival, but high risk of recurrence. Therapy should be directed at achieving local tumor control while preserving and even restoring neurological function.

Abnormal plasma sodium concentrations in patients treated with desmopressin for cranial diabetes insipidus: results of a long-term retrospective study

CONTEXT AND OBJECTIVE

Patients with cranial diabetes insipidus (CDI) are at risk of developing both hypernatraemia and hyponatraemia, due to the condition itself or secondary to treatment with vasopressin-analogues or during administration of i.v. fluids. We aimed to assess the frequency and impact of dysnatraemias in the inpatient (INPT) and outpatient (OPT) setting in desmopressin-treated CDI, comparing those with normal thirst with those with abnormal thirst.

DESIGN

The study included 192 patients with cranial diabetes, who were identified from the Beaumont Pituitary Database, a tertiary referral centre. Retrospective case note audit was performed and the clinical and biochemical information of 147 patients with CDI were available for analysis.

RESULTS

A total of 4142 plasma sodium measurements for 137 patients with normal thirst, and 385 plasma sodium measurements for ten patients with abnormal thirst were analysed. In those with normal thirst, the most common OPT abnormality was mild hyponatraemia (pNa(+) 131-134  mmol/l) in 27%, while 14.6% had more significant hyponatraemia (pNa(+) ≤130  mmol/l). Of those patients with normal thirst, 5.8% were admitted due to complications directly related to hyponatraemia. Compared with patients with normal thirst, those with abnormal thirst were more likely to develop significant OPT hypernatraemia (20% vs 1.4%, P=0.02) and significant INPT hyponatraemia (50% vs 11.1%, P 0.02).

CONCLUSION

OPT management of CDI is complicated by a significant incidence of hyponatraemia. In contrast, OPT hypernatraemia is almost exclusively a complication seen in adipsic CDI, who also had more frequent INPT hyponatraemia. CDI associated with thirst disorder requires increased physician attention and patient awareness of potential complications.

Chronic hypopituitarism is uncommon in survivors of aneurysmal subarachnoid haemorrhage

OBJECTIVE

The incidence of hypopituitarism after aneurysmal subarachnoid haemorrhage (SAH) is unclear from the conflicting reports in the literature. As routine neuroendocrine screening for hypopituitarism for all patients would be costly and logistically difficult, there is a need for precise data on the frequency of hypopituitarism and on factors which might predict the later development of pituitary dysfunction. We aimed to: (i) Establish the incidence of long-term hypopituitarism in patients with aneurysmal SAH. (ii) Determine whether data from patients' acute admission with SAH could predict the occurrence of long-term hypopituitarism.

DESIGN

One hundred patients were studied prospectively from the time of presentation with acute SAH. Plasma cortisol, plasma sodium and a variety of clinical and haemodynamic parameters were sequentially measured for the first 12 days of their acute admission. Forty-one patients then underwent dynamic pituitary testing at median 15 months following SAH (range 7-30 months), with insulin tolerance test (ITT) or, if contraindicated, a glucagon stimulation test (GST) plus short synacthen test (SST). If symptoms of cranial diabetes insipidus (CDI) were present, a water deprivation test was also performed.

RESULTS

Forty-one patients attended for follow-up dynamic pituitary testing. Although 14 of 100 had acute glucocorticoid deficiency immediately following SAH, only two of 41 had long-term adrenocorticotrophic hormone (ACTH) deficiency and four of 41 had growth hormone (GH) deficiency. None were hypothyroid or gonadotrophin deficient. None had chronic CDI or hyponatraemia. There was no association between acute glucocorticoid deficiency, acute CDI or acute hyponatraemia and long-term pituitary dysfunction.

CONCLUSION

Both anterior and posterior hypopituitarism are very uncommon following SAH and are not predicted by acute clinical, haemodynamic or endocrinological parameters. Routine neuroendocrine screening is not justified in SAH patients.

Species distributions and area relationships

The well-known species-area relationship is one of many scaling laws, or allometries, in ecology and biology that have received much attention over the years. We present a new derivation of this relationship based on Yule׳s theory of evolution of species. Using definitions of mutation rates, our analysis yields species-area exponents that are in close agreement with previously observed values.

Bibliometric evaluation of pediatric neurosurgery in North America

OBJECT

The application of bibliometric techniques to academic neurosurgery has been the focus of several recent publications. The authors provide here a detailed analysis of all active pediatric neurosurgeons in North America and their respective departments.

METHODS

Using Scopus and Google Scholar, a bibliometric profile for every known active pediatric neurosurgeon in North America was created using the following citation metrics: h-, contemporary h-, g-, and e-indices and the m-quotient. Various subgroups were compared. Departmental productivity from 2008 through 2013 was measured, and departments were ranked on the basis of cumulative h- and e-indices and the total number of publications and citations. Lorenz curves were created, and Gini coefficients were calculated for all departments with 4 or more members.

RESULTS

Three hundred twelve pediatric neurosurgeons (260 male, 52 female) were included for analysis. For the entire group, the median h-index, m-quotient, contemporary h-, g-, and e-indices, and the corrected g- and e-indices were 10, 0.59, 7, 18, 17, 1.14, and 1.01, respectively; the range for each index varied widely. Academic pediatric neurosurgeons associated with fellowship programs (compared with unassociated neurosurgeons), academic practitioners (compared with private practitioners), and men (compared with women) had superior measurements. There was no significant difference between American and Canadian pediatric neurosurgeons. The mean Gini coefficient for publications was 0.45 (range 0.18-0.70) and for citations was 0.53 (range 0.25-0.80).

CONCLUSIONS

This study represents the most exhaustive evaluation of academic productivity for pediatric neurosurgeons in North America to date. These results should serve as benchmarks for future studies.

A meta-analysis of spinal surgical site infection and vancomycin powder

Object

Surgical site infection (SSI) is a serious and costly complication of spinal surgery. There have been several conflicting reports on the use of intrawound vancomycin powder in decreasing SSI in spine surgery. The purpose of this study is to answer the question: “Does intrawound vancomycin powder reduce the rate of SSIs in spine surgery?”

Methods

A comprehensive search of multiple electronic databases and bibliographies was conducted to identify clinical studies that evaluated the rates of SSI with and without the use of intrawound vancomycin powder in spine surgery. Independent reviewers extracted data and graded the quality of each paper that met inclusion criteria. A random effects meta-analysis was then performed.

Results

The search identified 9 retrospective cohort studies (Level III evidence) and 1 randomized controlled trial (Level II evidence). There were 2574 cases and 106 infections in the control group (4.1%) and 2518 cases and 33 infections (1.3%) in the treatment group, yielding a pooled absolute risk reduction and relative risk reduction of 2.8% and 68%, respectively. The meta-analysis revealed the use of vancomycin powder to be protective in preventing SSI (relative risk = 0.34, 95% confidence interval 0.17–0.66, p = 0.021). The number needed to treat to prevent 1 SSI was 36. A subgroup analysis found that patients who had implants had a reduced risk of SSI with vancomycin powder (p = 0.023), compared with those who had noninstrumented spinal operations (p = 0.226).

Conclusions

This meta-analysis suggests that the use of vancomycin powder may be protective against SSI in open spinal surgery; however, the exact population in which it should be used is not clear. This benefit may be most appreciated in higher-risk populations or in facilities with a high baseline rate of infection.

Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 6: Preoperative antibiotics for shunt surgery in children with hydrocephalus: a systematic review and meta-analysis

OBJECT

The objective of this systematic review and meta-analysis was twofold: to answer the question "What is the evidence for the effectiveness of prophylactic intravenous antibiotics for infection prevention in shunt surgery?" and to make treatment recommendations based on the available evidence.

METHODS

The US National Library of Medicine PubMed/MEDLINE database and the Cochrane Database of Systematic Reviews were queried using MeSH headings and key words relevant to prophylactic antibiotic use in children undergoing a shunt operation. Abstracts were reviewed to identify which studies met the inclusion criteria. An evidentiary table was assembled summarizing the studies and the quality of evidence (Classes I-III). A meta-analysis was conducted using a random-effects model to calculate a cumulative estimate of treatment effect using risk ratio (RR). Heterogeneity was assessed using chi-square and I(2) statistics. A sensitivity analysis was also conducted. Based on the quality of the literature and the result of the meta-analysis, a recommendation was rendered (Level I, II, or III).

RESULTS

Nine studies (4 Class I, 3 Class II, and 2 Class III) met our inclusion criteria. Of 7 randomized controlled trials (RCTs), 3 were downgraded from Class I to Class II because of significant quality issues, and all RCTs were potentially underpowered. In only 2 Class in retrospective cohort studies were preoperative antibiotic agents found to be protective against shunt infection. When data from the individual studies were pooled together, the infection rate in the prophylactic antibiotics group was 5.9% compared with 10.7% in the control group. Using a random-effects model, the cumulative RR was 0.55 (95% CI 0.38-0.81), indicating a protective benefit of prophylactic preoperative intravenous antibiotics. A sensitivity analysis of RCTs only (n = 7) also demonstrated a statistical benefit, but an analysis of higher-quality RCTs only (n = 4) did not. Conclusions Within the limits of this systematic review and meta-analysis, administration of preoperative antibiotic agents for shunt surgery in children was found to lower the infection risk (quality of evidence: Class II; strength of recommendation, Level II).

RECOMMENDATION

The use of preoperative antibiotic agents can be recommended to prevent shunt infection in patients with hydrocephalus. It was only by combining the results of the various underpowered studies (meta-analysis) that the use of preoperative antibiotics for shunt surgery in children was shown to lower the risk of shunt infection.

STRENGTH OF RECOMMENDATION

Level II, moderate degree of clinical certainty.

Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 7: Antibiotic-impregnated shunt systems versus conventional shunts in children: a systematic review and meta-analysis

OBJECT

The objective of this systematic review and meta-analysis was to answer the following question: Are antibiotic-impregnated shunts (AISs) superior to standard shunts (SSs) at reducing the risk of shunt infection in pediatric patients with hydrocephalus?

METHODS

Both the US National Library of Medicine PubMed/MEDLINE database and the Cochrane Database of Systematic Reviews were queried using MeSH headings and key words relevant to AIS use in children. Abstracts were reviewed, after which studies meeting the inclusion criteria were selected. An evidentiary table was assembled summarizing the studies and the quality of their evidence (Classes I-III). A meta-analysis was conducted using a random-effects model to calculate a cumulative estimate of treatment effect using risk ratio (RR). Heterogeneity was assessed using the chi-square and I(2) statistics. Based on the quality of the literature and the result of the meta-analysis, a recommendation was rendered (Level I, II, or III).

RESULTS

Six studies, all Class III, met our inclusion criteria. All but one study focused on a retrospective cohort and all but one were conducted at a single institution. Four of the studies failed to demonstrate a lowered infection rate with the use of an AIS. However, when the data from individual studies were pooled together, the infection rate in the AIS group was 5.5% compared with 8.6% in the SS group. Using a random-effects model, the cumulative RR was 0.51 (95% CI 0.29-0.89, p < 0.001), indicating that a shunt infection was 1.96 times more likely in patients who received an SS.

CONCLUSIONS

We recommend AIS tubing because of the associated lower risk of shunt infection compared to the use of conventional silicone hardware (quality of evidence: Class III; strength of recommendation: Level III).

RECOMMENDATION

Antibiotic-impregnated shunt (AIS) tubing may be associated with a lower risk of shunt infection compared with conventional silicone hardware and thus is an option for children who require placement of a shunt.

STRENGTH OF RECOMMENDATION

Level III, unclear degree of clinical certainty.

Case-control studies in neurosurgery

OBJECT

Observational studies, such as cohort and case-control studies, are valuable instruments in evidence-based medicine. Case-control studies, in particular, are becoming increasingly popular in the neurosurgical literature due to their low cost and relative ease of execution; however, no one has yet systematically assessed these types of studies for quality in methodology and reporting.

METHODS

The authors performed a literature search using PubMed/MEDLINE to identify all studies that explicitly identified themselves as "case-control" and were published in the JNS Publishing Group journals (Journal of Neurosurgery, Journal of Neurosurgery: Pediatrics, Journal of Neurosurgery: Spine, and Neurosurgical Focus) or Neurosurgery. Each paper was evaluated for 22 descriptive variables and then categorized as having either met or missed the basic definition of a case-control study. All studies that evaluated risk factors for a well-defined outcome were considered true case-control studies. The authors sought to identify key features or phrases that were or were not predictive of a true case-control study. Those papers that satisfied the definition were further evaluated using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist.

RESULTS

The search detected 67 papers that met the inclusion criteria, of which 32 (48%) represented true case-control studies. The frequency of true case-control studies has not changed with time. Use of odds ratios (ORs) and logistic regression (LR) analysis were strong positive predictors of true case-control studies (for odds ratios, OR 15.33 and 95% CI 4.52-51.97; for logistic regression analysis, OR 8.77 and 95% CI 2.69-28.56). Conversely, negative predictors included focus on a procedure/intervention (OR 0.35, 95% CI 0.13-0.998) and use of the word "outcome" in the Results section (OR 0.23, 95% CI 0.082-0.65). After exclusion of nested case-control studies, the negative correlation between focus on a procedure/intervention and true case-control studies was strengthened (OR 0.053, 95% CI 0.0064-0.44). There was a trend toward a negative association between the use of survival analysis or Kaplan-Meier curves and true case-control studies (OR 0.13, 95% CI 0.015-1.12). True case-control studies were no more likely than their counterparts to use a potential study design "expert" (OR 1.50, 95% CI 0.57-3.95). The overall average STROBE score was 72% (range 50-86%). Examples of reporting deficiencies were reporting of bias (28%), missing data (55%), and funding (44%).

CONCLUSIONS

The results of this analysis show that the majority of studies in the neurosurgical literature that identify themselves as "case-control" studies are, in fact, labeled incorrectly. Positive and negative predictors were identified. The authors provide several recommendations that may reverse the incorrect and inappropriate use of the term "case-control" and improve the quality of design and reporting of true case-control studies in neurosurgery.

Methodology and reporting of meta-analyses in the neurosurgical literature

OBJECT

Neurosurgeons are inundated with vast amounts of new clinical research on a daily basis, making it difficult and time-consuming to keep up with the latest literature. Meta-analysis is an extension of a systematic review that employs statistical techniques to pool the data from the literature in order to calculate a cumulative effect size. This is done to answer a clearly defined a priori question. Despite their increasing popularity in the neurosurgery literature, meta-analyses have not been scrutinized in terms of reporting and methodology.

METHODS

The authors performed a literature search using PubMed/MEDLINE to locate all meta-analyses that have been published in the JNS Publishing Group journals (Journal of Neurosurgery, Journal of Neurosurgery: Pediatrics, Journal of Neurosurgery: Spine, and Neurosurgical Focus) or Neurosurgery. Accepted checklists for reporting (PRISMA) and methodology (AMSTAR) were applied to each meta-analysis, and the number of items within each checklist that were satisfactorily fulfilled was recorded. The authors sought to answer 4 specific questions: Are meta-analyses improving 1) with time; 2) when the study met their definition of a meta-analysis; 3) when clinicians collaborated with a potential expert in meta-analysis; and 4) when the meta-analysis was the only focus of the paper?

RESULTS

Seventy-two meta-analyses were published in the JNS Publishing Group journals and Neurosurgery between 1990 and 2012. The number of published meta-analyses has increased dramatically in the last several years. The most common topics were vascular, and most were based on observational studies. Only 11 papers were prepared using an established checklist. The average AMSTAR and PRISMA scores (proportion of items satisfactorily fulfilled divided by the total number of eligible items in the respective instrument) were 31% and 55%, respectively. Major deficiencies were identified, including the lack of a comprehensive search strategy, study selection and data extraction, assessment of heterogeneity, publication bias, and study quality. Almost one-third of the papers did not meet our basic definition of a meta-analysis. The quality of reporting and methodology was better 1) when the study met our definition of a meta-analysis; 2) when one or more of the authors had experience or expertise in conducting a meta-analysis; 3) when the meta-analysis was not conducted alongside an evaluation of the authors' own data; and 4) in more recent studies.

CONCLUSIONS

Reporting and methodology of meta-analyses in the neurosurgery literature is excessively variable and overall poor. As these papers are being published with increasing frequency, neurosurgical journals need to adopt a clear definition of a meta-analysis and insist that they be created using checklists for both reporting and methodology. Standardization will ensure high-quality publications.

Hyponatremia following mild/moderate subarachnoid hemorrhage is due to SIAD and glucocorticoid deficiency and not cerebral salt wasting

CONTEXT

Hyponatremia is common after acute subarachnoid hemorrhage (SAH) but the etiology is unclear and there is a paucity of prospective data in the field. The cause of hyponatremia is variously attributed to the syndrome of inappropriate antidiuresis (SIAD), acute glucocorticoid insufficiency, and the cerebral salt wasting syndrome (CSWS).

OBJECTIVE

The objective was to prospectively determine the etiology of hyponatremia after SAH using sequential clinical examination and biochemical measurement of plasma cortisol, arginine vasopressin (AVP), and brain natriuretic peptide (BNP).

DESIGN

This was a prospective cohort study.

SETTING

The setting was the National Neurosurgery Centre in a tertiary referral centre in Dublin, Ireland.

PATIENTS

One hundred patients with acute nontraumatic aneurysmal SAH were recruited on presentation.

INTERVENTIONS

Clinical examination and basic biochemical evaluation were performed daily. Plasma cortisol at 0900 hours, AVP, and BNP concentrations were measured on days 1, 2, 3, 4, 6, 8, 10, and 12 following SAH. Those with 0900 hours plasma cortisol<300 nmol/L were empirically treated with iv hydrocortisone.

MAIN OUTCOME MEASURES

Plasma sodium concentration was recorded daily along with a variety of clinical and biochemical criteria. The cause of hyponatremia was determined clinically. Later measurement of plasma AVP and BNP concentrations enabled a firm biochemical diagnosis of the cause of hyponatremia to be made.

RESULTS

Forty-nine of 100 developed hyponatremia<135 mmol/L, including 14/100<130 mmol/L. The cause of hyponatremia, and determined by both clinical examination and biochemical hormone measurement, was SIAD in 36/49 (71.4%), acute glucocorticoid insufficiency in 4/49 (8.2%), incorrect iv fluids in 5/49 (10.2%), and hypovolemia in 5/49 (10.2%). There were no cases of CSWS.

CONCLUSIONS

The most common cause of hyponatremia after acute nontraumatic aneurysmal SAH is SIAD. Acute glucocorticoid insufficiency accounts for a small but significant number of cases. We found no cases of CSWS.

An analysis of publication productivity for 1225 academic neurosurgeons and 99 departments in the United States

OBJECT

Bibliometrics is defined as the study of statistical and mathematical methods used to quantitatively analyze scientific literature. The application of bibliometrics in neurosurgery is in its infancy. The authors calculate a number of publication productivity measures for almost all academic neurosurgeons and departments within the US.

METHODS

The h-index, g-index, m-quotient, and contemporary h-index (hc-index) were calculated for 1225 academic neurosurgeons in 99 (of 101) programs listed by the Accreditation Council for Graduate Medical Education in January 2013. Three currently available citation databases were used: Google Scholar, Scopus, and Web of Science. Bibliometric profiles were created for each surgeon. Comparisons based on academic rank (that is, chairperson, professor, associate, assistant, and instructor), sex, and subspecialties were performed. Departments were ranked based on the summation of individual faculty h-indices. Calculations were carried out from January to February 2013.

RESULTS

The median h-index, g-index, hc-index, and m-quotient were 11, 20, 8, and 0.62, respectively. All indices demonstrated a positive relationship with increasing academic rank (p < 0.001). The median h-index was 11 for males (n = 1144) and 8 for females (n = 81). The h-index, g-index and hc-index significantly varied by sex (p < 0.001). However, when corrected for academic rank, this difference was no longer significant. There was no difference in the m-quotient by sex. Neurosurgeons with subspecialties in functional/epilepsy, peripheral nerve, radiosurgery, neuro-oncology/skull base, and vascular have the highest median h-indices; general, pediatric, and spine neurosurgeons have the lowest median h-indices. By summing the manually calculated Scopus h-indices of all individuals within a department, the top 5 programs for publication productivity are University of California, San Francisco; Barrow Neurological Institute; Johns Hopkins University; University of Pittsburgh; and University of California, Los Angeles.

CONCLUSIONS

This study represents the most detailed publication analysis of academic neurosurgeons and their programs to date. The results for the metrics presented should be viewed as benchmarks for comparison purposes. It is our hope that organized neurosurgery will adopt and continue to refine bibliometric profiling of individuals and departments.

Acute glucocorticoid deficiency and diabetes insipidus are common after acute traumatic brain injury and predict mortality

CONTEXT

Published data demonstrates that hypopituitarism is common after traumatic brain injury (TBI). Hormone deficiencies are transient in many, but the natural history of the acute changes after TBI has not been documented. In addition, it is not clear whether there are any early parameters that accurately predict the development of permanent hypopituitarism.

OBJECTIVES

There were 3 main objectives of this study: 1) to describe the natural history of plasma cortisol (PC) changes and sodium balance after TBI; 2) to identify whether acute hypocortisolemia or cranial diabetes insipidus (CDI) predict mortality; and 3) to identify whether the acute pituitary dysfunction predicts the development of chronic anterior hypopituitarism.

DESIGN

Each TBI patient underwent sequential measurement of PC, plasma sodium, urine osmolality, and fluid balance after TBI. All other anterior pituitary hormones were measured on day 10 after TBI. The results from 15 surgical comparisons defined a PC less than 300 nmol/L as inappropriately low for an acutely ill patient. CDI was diagnosed according to standard criteria. Surviving TBI patients underwent dynamic anterior pituitary testing at least 6 months after TBI.

SETTING

The patients were recruited from the Irish National Neurosurgery Centre.

PATIENTS

One hundred sequential TBI patients were recruited. Fifteen patients admitted to Intensive Therapy Unit (ITU) after major surgery were recruited as comparison patients.

MAIN OUTCOME MEASURES

PC in TBI patients was compared with that of comparison patients. The mortality rate was compared between TBI patients with and without acute hypocortisolemia. Results of follow-up dynamic pituitary testing were compared between those with and without acute hypocortisolemia.

RESULTS

Most of the TBI patients (78%) developed inappropriately low PC after TBI. Low PC and CDI were predictive of mortality. Thirty-nine percent of the patients who had follow-up testing had at least 1 pituitary hormone deficit, all of whom had had previous acute hypocortisolemia or CDI.

CONCLUSIONS

Acute hypocortisolemia and CDI are predictive of mortality and long-term pituitary deficits in TBI.

Serum prolactin concentration at presentation of non-functioning pituitary macroadenomas

OBJECTIVE

Serum PRL levels at presentation may be useful in distinguishing between disconnection hyperprolactinemia in non-secretory pituitary adenomas and prolactinomas in order to guide appropriate therapy; however, there is a debate regarding the discriminatory PRL thresholds. We aimed to examine PRL concentrations at presentation in a cohort of histologically proven non-functioning pituitary adenomas (NFPA).

DESIGN AND METHODS

Retrospective case note analysis was performed. Clinical, biochemical, histopathological and radiological data were recorded and analyzed. Complete data were available for 250 subjects with NFPA.

RESULTS

Of the study population, 44.8% were hyperprolactinemic at presentation, 55.3% of whom were female. Of those with hyperprolactinemia, 73.2% had PRL<1000 mIU/l on presentation, 24.1% had PRL between 1000 and 1999 mIU/l. Only 2.7% (no.=3 females, 1.2% whole cohort) had PRL>2000 mIU/l (94.3 ng/ml), 2 of whom were pregnant. No male subject and no subjects with an intrasellar macroadenoma had serum PRL>1000 mIU/l (47.2 ng/ml). Overall, serum PRL was not higher among 43 subjects taking medications known to raise PRL.

CONCLUSIONS

Our data support recent evidence that the serum PRL concentration is rarely >1000 mIU/l in males, or >2000 mIU/l in females, with non-functioning macroadenomas and that, once other contributing factors to the hyperprolactinemia have been excluded, a trial of dopamine agonist therapy for such lesions is indicated.

Management and outcome of focal low-grade brainstem tumors in pediatric patients: the St. Jude experience

OBJECT

Whereas diffuse intrinsic pontine gliomas generally have a short symptom duration and more cranial nerve involvement, focal brainstem gliomas are commonly low grade, with fewer cranial neuropathies. Although these phenotypic distinctions are not absolute predictors of outcome, they do demonstrate correlation in most cases. Because there is a limited literature on focal brainstem gliomas in pediatric patients, the objective of this paper was to report the management and outcome of these tumors.

METHODS

The authors reviewed the records of all children diagnosed with radiographically confirmed low-grade focal brainstem gliomas from 1986 to 2010. Each patient underwent biopsy or resection for tissue diagnosis. Event-free survival (EFS) and overall survival were evaluated. Univariate analysis was conducted to identify demographic and treatment variables that may affect EFS.

RESULTS

Fifty-two patients (20 girls, 32 boys) with follow-up data were identified. Median follow-up was 10.0 years, and the median age at diagnosis was 6.5 years (range 1-17 years). The tumor locations were midbrain (n = 22, 42%), pons (n = 15, 29%), and medulla (n = 15, 29%). Surgical extirpation was the primary treatment in 25 patients (48%). The 5- and 10-year EFS and overall survival were 59%/98% and 52%/90%, respectively. An event or treatment failure occurred in 24 patients (46%), including 5 deaths. Median time to treatment failure was 3.4 years. Disease progression in the other 19 patients transpired within 25.1 months of diagnosis. Thirteen of these patients received radiation, including 11 within 2 months of primary treatment failure. Although children with intrinsic tumors had slightly better EFS at 5 years compared with those with exophytic tumors (p = 0.054), this difference was not significant at 10 years (p = 0.147). No other variables were predictive of EFS.

CONCLUSIONS

Surgery suffices in many children with low-grade focal brainstem gliomas. Radiation treatment is often reserved for disease progression but offers comparable disease control following biopsy. In the authors' experience, combining an assessment of clinical course, imaging, and tumor biopsy yields a reasonable model for managing children with focal brainstem tumors.

Sci-Fri AM: Imaging - 03: Temperature dependence of a SiPM detector for an MR compatible PET system

Silicon photomultiplier (SiPM) detectors are rapidly becoming the detector of choice for research and development of new detectors for positron emission tomography (PET) due to their combination of high gain, fast timing, compact form factor and ability to function in a magnetic field. We are investigating using SiPM based detectors in a compact PET system designed to be inserted into a 7T animal MRI system and enable simultaneous PET/MRI imaging. In order to understand the level of thermal stability required for this PET system, we examined the stability of a prototype SiPM detector vs. temperature. A detector was constructed using a SensL SPMArray4 SiPM array coupled to a LYSO scintillator crystal array. The temperature of the detector was varied between 23 and 60°C in 5°C steps. At each temperature setting data were collected to characterize the detector flood histogram, photopeak amplitude and energy resolution at 511 keV, timing resolution and signal arrival time. While the flood image showed no noticeable changes with temperature, the 511 keV photopeak amplitude showed a linear decrease of 1.5%/°C and the energy resolution degraded by 0.08%/°C. The timing resolution degraded by 1.5 ns, from 3.5 ns to 5 ns when the temperature changed from 23 to 60°C. Over this temperature range there was a shift in the signal arrival time of approximately 3 ns. These results demonstrate that the detector can be operated over a wide range of temperature, giving a large degree of flexibility in choosing an operating temperature set-point for our PET system.

Anterior hypopituitarism is rare and autoimmune disease is common in adults with idiopathic central diabetes insipidus

OBJECTIVE

Central diabetes insipidus is a rare clinical condition with a heterogenous aetiology. Up to 40% of cases are classified as idiopathic, although many of these are thought to have an autoimmune basis. Published data have suggested that anterior hypopituitarism is common in childhood-onset idiopathic diabetes insipidus. We aimed to assess the incidence of anterior hypopituitarism in a cohort of adult patients with idiopathic diabetes insipidus.

DESIGN AND PATIENTS

We performed a retrospective review of the databases of two pituitary investigation units. This identified 39 patients with idiopathic diabetes insipidus. All had undergone magnetic resonance imaging scanning and dynamic pituitary testing (either insulin tolerance testing or GHRH/arginine and short synacthen testing) to assess anterior pituitary function.

RESULTS

One patient had partial growth hormone deficiency; no other anterior pituitary hormonal deficits were found. Thirty-three percent had at least one autoimmune disease in addition to central diabetes insipidus.

CONCLUSIONS

Our data suggest that anterior hypopituitarism is rare in adult idiopathic diabetes insipidus. Routine screening of these patients for anterior hypopituitarism may not, therefore, be indicated. The significant prevalence of autoimmune disease in this cohort supports the hypothesis that idiopathic diabetes insipidus may have an autoimmune aetiology.

Platelet reactivity in type 2 diabetes mellitus: a comparative analysis with survivors of myocardial infarction and the role of glycaemic control

Patients with type 2 diabetes mellitus exhibit considerable platelet dysfunction, though this is poorly characterized in patients with diabetes taking aspirin for the primary prevention of cardiovascular events. We sought to compare platelet function in this patient population with that of a high-risk group of non-diabetic subjects with a history of previous myocardial infarction (MI), and to assess whether glycaemic control impacts on platelet function.

METHODS

Platelet aggregation was measured in response to incremental concentrations of five platelet agonists using light transmission aggregometry. All patients were taking aspirin, and aspirin insensitivity was defined as ≥ 20% arachidonic acid (AA) mediated aggregation. Patients with diabetes were divided according to glycaemic control (HbA(1c)): optimal ≤ 6.5, good 6.6-7.4 and suboptimal ≥ 7.5%.

RESULTS

In total, 85 patients with type 2 diabetes and 35 non-diabetic patients with previous MI were recruited. Compared to MI patients, diabetes patients had increased aggregation in response to multiple concentrations of epinephrine, collagen, adenosine diphosphate and AA. Aspirin insensitivity was more common in type 2 diabetes (15% vs. 0%, p=0.037). Platelet aggregation was increased in response to several agonists patients with suboptimal glycaemic control compared to patients with optimal control. Aspirin insensitivity was also more common in patients with suboptimal glycaemic control compared to those with good or optimal control (26.0% vs. 8.3% vs. 4%, p=0.04).

CONCLUSION

Patients with type 2 diabetes mellitus, without proven vascular disease, exhibit platelet dysfunction and have increased platelet aggregation and aspirin insensitivity compared to non-diabetic patients with previous MI. Platelet dysfunction in diabetes is more severe in patients with suboptimal glycaemic control.

Antibiotic-impregnated shunt systems versus standard shunt systems: a meta- and cost-savings analysis

OBJECT

Infection is a serious and costly complication of CSF shunt implantation. Antibiotic-impregnated shunts (AISs) were introduced almost 10 years ago, but reports on their ability to decrease the infection rate have been mixed. The authors conducted a meta-analysis assessing the extent to which AISs reduce the rate of shunt infection compared with standard shunts (SSs). They also examined cost savings to determine the degree to which AISs could decrease infection-related hospital expenses.

METHODS

After conducting a comprehensive search of multiple electronic databases to identify studies that evaluated shunt type and used shunt-related infection as the primary outcome, 2 reviewers independently evaluated study quality based on preestablished criteria and extracted data. A random effects meta-analysis of eligible studies was then performed. For studies that demonstrated a positive effect with the AIS, a cost-savings analysis was conducted by calculating the number of implanted shunts needed to prevent a shunt infection, assuming an additional cost of $400 per AIS system and $50,000 to treat a shunt infection.

RESULTS

Thirteen prospective or retrospective controlled cohort studies provided Level III evidence, and 1 prospective randomized study provided Level II evidence. "Shunt infection" was generally uniformly defined among the studies, but the availability and detail of baseline demographic data for the control (SS) and treatment (AIS) groups within each study were variable. There were 390 infections (7.0%) in 5582 procedures in the control group and 120 infections (3.5%) in 3467 operations in the treatment group, yielding a pooled absolute risk reduction (ARR) and relative risk reduction (RRR) of 3.5% and 50%, respectively. The meta-analysis revealed the AIS to be statistically protective in all studies (risk ratio = 0.46, 95% CI 0.33-0.63) and in single-institution studies (risk ratio = 0.38, 95% CI 0.25-0.58). There was some evidence of heterogeneity when studies were analyzed together (p = 0.093), but this heterogeneity was reduced when the studies were analyzed separately as single institution versus multiinstitutional (p > 0.10 for both groups). Seven studies showed the AIS to be statistically protective against infection with an ARR and RRR ranging from 1.7% to 14.2% and 34% to 84%, respectively. The number of shunt operations requiring an AIS to prevent 1 shunt infection ranged from 7 to 59. Assuming 200 shunt cases per year, the annual savings for converting from SSs to AISs ranged from $90,000 to over $1.3 million.

CONCLUSIONS

While the authors recognized the inherent limitations in the quality and quantity of data available in the literature, this meta-analysis revealed a significant protective benefit with AIS systems, which translated into substantial hospital savings despite the added cost of an AIS. Using previously developed guidelines on treatment, the authors strongly encourage the use of AISs in all patients with hydrocephalus who require a shunt, particularly those at greatest risk for infection.

Secondary resistance to cabergoline therapy in a macroprolactinoma: a case report and literature review

Primary resistance to dopamine agonists occurs in 10-15% of prolactinomas but secondary resistance following initial biochemical and anti-proliferative response is very rare and has only been hitherto described in four previous cases, two with bromocriptine and two with cabergoline. We describe a case of a 57-year-old woman who presented with a large macroprolactinoma with suprasellar extension. She was initially treated with bromocriptine therapy with a resolution of symptoms, marked reduction in prolactin concentration and complete tumour shrinkage; a response which was subsequently maintained on cabergoline. After 8 years of dopamine agonist therapy, her prolactin concentration began to rise and there was symptomatic recurrence of her tumour despite escalating doses of cabergoline up to 6 mg weekly. Non-compliance was outruled by observed inpatient drug administration. The patient underwent surgical debulking followed by radiotherapy with good response. This case adds to the previous two cases of secondary resistance to cabergoline therapy in prolactinomas a marked initial response. While the mechanism of secondary resistance remains unknown and not possible to predict, close observation of prolactinoma patients on treatment is necessary.

Pituitary dysfunction following traumatic brain injury or subarachnoid haemorrhage - in "Endocrine Management in the Intensive Care Unit"

Traumatic brain injury and subarachnoid haemorrhage are important causes of morbidity and mortality in the developed world. There is a large body of evidence that demonstrates that both conditions may adversely affect pituitary function in both the acute and chronic phases of recovery. Diagnosis of hypopituitarism and accurate treatment of pituitary disorders offers the opportunity to improve mortality and outcome in both traumatic brain injury and subarachnoid haemorrhage. In this article, we will review the history and pathophysiology of pituitary function in the acute phase following traumatic brain injury and subarachnoid haemorrhage, and we will discuss in detail three key aspects of pituitary dysfunction which occur in the early course of TBI; acute cortisol deficiency, diabetes insipidus and SIAD.

Somnolence in adult craniopharyngioma patients is a common, heterogeneous condition that is potentially treatable

CONTEXT AND OBJECTIVE

Somnolence and obesity are prevalent in craniopharyngioma patients. We hypothesized that somnolence was because of obstructive sleep apnoea in craniopharyngioma patients.

DESIGN, PATIENTS AND MEASUREMENTS

We assessed prevalence of somnolence and sleep apnoea in 28 craniopharyngioma and 23 obese controls attending a tertiary referral centre, by means of the Epworth Sleepiness Score (ESS) and polysomnography. All subjects with sleep apnoea were offered continuous positive airway pressure therapy (CPAP) or modafinil. All craniopharyngioma patients, with unexplained somnolence, were offered modafinil.

RESULTS

Somnolence was reported by 20/28 (71·5%) craniopharyngioma patients and 4/23 (17%) obese subjects (P < 0·001). Median ESS was 7·5 (IQR 6, 10·7) in craniopharyngioma patients and 4·0 (4,8) in controls, P < 0·01. Eleven somnolent craniopharyngioma patients had obstructive sleep apnoea, in whom treatment led to a reduction in ESS by 6·4 ± 1·4, P = 0·01. Among the remaining nine patients, five were offered modafinil therapy, of whom four had benefit, three were not compliant with hormone replacement, and one died before intervention. There was no difference in the prevalence of obstructive sleep apnoea between craniopharyngioma (n = 13, 46%) and obese subjects (n = 14, 61%, P = 0·4). Body mass index (BMI) does not correlate with apnoea hypopnoea index [apnoea - hypopnoea index (AHI), r = 0·25, P = 0·08], which suggests that obesity alone does not explain the prevalence of sleep apnoea in craniopharyngioma patients.

CONCLUSIONS

Somnolence is common in craniopharyngioma patients and in the majority is because of obstructive sleep apnoea. An additional group of somnolent craniopharyngioma patients benefits from modafinil.

Gastric pacing for diabetic gastroparesis--does it work?

The management of diabetic gastroparesis resistant to medical therapy is very difficult Gastric electrical stimulation (GES) is a relatively new therapeutic modality which has shown some promise in international trials. It has seen use in four patients in Ireland. Our aim was to determine if GES improved patients' outcomes in terms of duration and cost of inpatient stay and glycaemic control. We reviewed the patients' case notes and calculated the number of days spent as an inpatient with symptomatic gastroparesis pre and post pacemaker, the total cost of these admissions, and patients' average HbA1c pre and post GES. Mean length of stay in the year pre GES was 81.75 days and 62.25 days in the year post GES (p=0.89). There was also no improvement in glycaemic control following GES. GES has been ineffective in improving length of inpatient stay and glycaemic control in our small patient cohort.

Morbidity and mortality in patients with craniopharyngioma after surgery

OBJECTIVE

Craniopharyngioma (CP) is a benign tumour of the suprasellar region that is associated with increased morbidity and mortality in comparison with other causes of hypopituitarism. We aimed to establish the rate and causes of mortality and morbidity in patients with CP who attended our centre.

DESIGN

We performed a retrospective case note audit of patients with CP who were managed by our service. We established the standardized mortality ratio (SMR) for patients with CP. We compared obesity prevalence with two other hypopituitary groups who are managed by our service.

PATIENTS

We identified 70 patients with CP, 97% of whom had undergone surgery and 42% radiotherapy. We compared the prevalence of obesity with that of 89 patients with hypopituitarism secondary to surgery for nonfunctioning pituitary adenoma and 29 patients with post-traumatic hypopituitarism (PTHP).

MEASUREMENTS

Standardized mortality ratio for patients with CP was 8.75 (95% CI of 5.4-13.3); SMR for women was 10.51 (95% CI 5.04-19.3) and 7.55 (95% CI 3.77-13.52) for men. The rates of growth hormone (GH), gonadotrophin, adrenocorticotrophic hormone (ACTH) and TSH deficiencies were 91%, 93.5%, 92% and 86%, respectively. The rate of diabetes insipidus (DI) was 81%; 7.1% had adipsic DI. Dyslipidaemia was present in 46.9% and diabetes mellitus in 11.5%. Obesity affected 66% of patients with CP, 47% of patients with nonfunctioning adenoma and 31% of those with PTHP (P < 0.001).

CONCLUSIONS

Patients with CP suffer from high rates of mortality and morbidity. The underlying causes for mortality and for obesity in this population remain poorly understood.

Motion compensation for fully 4D PET reconstruction using PET superset data

Fully 4D PET image reconstruction is receiving increasing research interest due to its ability to significantly reduce spatiotemporal noise in dynamic PET imaging. However, thus far in the literature, the important issue of correcting for subject head motion has not been considered. Specifically, as a direct consequence of using temporally extensive basis functions, a single instance of movement propagates to impair the reconstruction of multiple time frames, even if no further movement occurs in those frames. Existing 3D motion compensation strategies have not yet been adapted to 4D reconstruction, and as such the benefits of 4D algorithms have not yet been reaped in a clinical setting where head movement undoubtedly occurs. This work addresses this need, developing a motion compensation method suitable for fully 4D reconstruction methods which exploits an optical tracking system to measure the head motion along with PET superset data to store the motion compensated data. List-mode events are histogrammed as PET superset data according to the measured motion, and a specially devised normalization scheme for motion compensated reconstruction from the superset data is required. This work proceeds to propose the corresponding time-dependent normalization modifications which are required for a major class of fully 4D image reconstruction algorithms (those which use linear combinations of temporal basis functions). Using realistically simulated as well as real high-resolution PET data from the HRRT, we demonstrate both the detrimental impact of subject head motion in fully 4D PET reconstruction and the efficacy of our proposed modifications to 4D algorithms. Benefits are shown both for the individual PET image frames as well as for parametric images of tracer uptake and volume of distribution for (18)F-FDG obtained from Patlak analysis.

The syndrome of inappropriate antidiuretic hormone: prevalence, causes and consequences

Hyponatraemia is the commonest electrolyte abnormality found in hospital inpatients, and is associated with a greatly increased morbidity and mortality. The syndrome of inappropriate antidiuretic hormone (SIADH) is the most frequent cause of hyponatraemia in hospital inpatients. SIADH is the clinical and biochemical manifestation of a wide range of disease processes, and every case warrants investigation of the underlying cause. In this review, we will examine the prevalence, pathophysiology, clinical characteristics and clinical consequences of hyponatraemia due to SIADH.

Outcomes following single-treatment Gamma Knife surgery for trigeminal neuralgia with a minimum 3-year follow-up

Object

Gamma Knife surgery (GKS) has been shown to be effective in treating trigeminal neuralgia (TN). Existing studies have demonstrated success rates of 69.1–85% with median follow-up intervals of 19–60 months. However, series with uniform long-term follow-up data for all patients have been lacking. In the present study the authors examined outcomes in a series of patients with TN who underwent a single GKS treatment followed by a minimum follow-up of 36 months. They used a clinical scale that simplifies the reporting of outcome data for patients with TN.

Methods

Fifty-three consecutive patients with typical, intractable TN received a median maximum radiation dose of 80 Gy applied with a single 4-mm isocenter to the affected trigeminal nerve. Follow-up data were obtained by clinical examination and questionnaire. Outcome results were categorized into the following classes (in order of decreasing success): Class 1A, complete pain relief without medications; 1B, complete pain relief with either a decrease or no change in medications; 1C, ≥ 50% pain relief without medications; 1D, ≥ 50% pain relief with either a decrease or no change in medications; and Class 2, < 50% pain relief and/or increase in medications. Patients with Class 1A–1D outcome (equivalent to Barrow Neurological Institute Grades I–IIIb) were considered to have a good treatment outcome, whereas in patients with Class 2 outcome (equivalent to Barrow Neurological Institute Grades IV and V) treatment was considered to have failed.

Results

A good treatment outcome from initial GKS was achieved in 31 (58.5%) patients for whom the mean follow-up period was 48 months (range 36–66 months). Outcomes at last follow-up were reflected by class status: Class 1A, 32.1% of patients; 1B, 1.9%; 1C, 3.8%; 1D, 20.8%; and Class 2, 41.5%. Statistical analysis showed no difference in outcomes between patients previously treated with microvascular decompression or rhizotomy compared with patients with no previous surgical treatments. Thirty-six percent of patients reported some degree of posttreatment facial numbness. Anesthesia dolorosa did not develop in any patient.

Conclusions

Despite a time-dependent deterioration in the success rate of GKS for medically intractable TN, the authors' study showed that > 50% of patients can be expected to have a good outcome based on their scoring system, with ~ 33% having an ideal outcome (pain free with no need for medications). Long-term data, as those presented here, are important when counseling patients on their treatment options.