Publication productivity of neurosurgeons in Great Britain and Ireland.

OBJECT: Bibliometrics are the methods used to quantitatively analyze scientific literature. In this study, bibliometrics were used to quantify the scientific output of neurosurgical departments throughout Great Britain and Ireland. METHODS: A list of neurosurgical departments was obtained from the Society of British Neurological Surgeons website. Individual departments were contacted for an up-to-date list of consultant (attending) neurosurgeons practicing in these departments. Scopus was used to determine the h-index and m-quotient for each neurosurgeon. Indices were measured by surgeon and by departmental mean and total. Additional information was collected about the surgeon's sex, title, listed superspecialties, higher research degrees, and year of medical qualification. RESULTS: Data were analyzed for 315 neurosurgeons (25 female). The median h-index and m-quotient were 6.00 and 0.41, respectively. These were significantly higher for professors (h-index 21.50; m-quotient 0.71) and for those with an additional MD or PhD (11.0; 0.57). There was no significant difference in h-index, m-quotient, or higher research degrees between the sexes. However, none of the 16 British neurosurgery professors were female. Neurosurgeons who specialized in functional/epilepsy surgery ranked highest in terms of publication productivity. The 5 top-scoring departments were those in Addenbrooke's Hospital, Cambridge; St. George's Hospital, London; Great Ormond Street Hospital, London; National Hospital for Neurology and Neurosurgery, Queen Square, London; and John Radcliffe Hospital, Oxford. CONCLUSIONS: The h-index is a useful bibliometric marker, particularly when comparing between studies and individuals. The m-quotient reduces bias toward established researchers. British academic neurosurgeons face considerable challenges, and women remain underrepresented in both clinical and academic neurosurgery in Britain and Ireland.

An investigation into the clinical impacts of lowering shunt opening pressure in idiopathic normal pressure hydrocephalus: A case series.

INTRODUCTION: Idiopathic normal pressure hydrocephalus (iNPH) is a shunt- reversible syndrome of the elderly. Shunt management is aimed at achieving a balance between clinical improvement and the complications associated with overdrainage. Although clinical improvement occurs at low pressure, these benefits may be negated by the increase in complication rates observed at lower pressures. The addition of gravity-switch devices has been shown to reduce over drainage problems even at a low valve pressure setting. At our centre the Miethke proGAV is used and commonly lowered below 5 cmH2O to gain further clinical improvement. OBJECT: To determine whether lowering the opening pressure to below 5cmH2O using the proGAV valve in iNPH patients results in a) improved clinical features; and b) no significant increase in complication rates. METHODS: A retrospective case series of iNPH patients was undertaken with 24 patients who had the proGAV shunt system inserted with an initial opening pressure of 5cmH2O. Exclusion criteria were secondary NPH, shunt system other than proGAV inserted, no valve adjustment to below 5cmH2O and inadequate follow-up. Outcome measures were clinical improvement (gait, cognition and urinary continence) and complications (subdural haematoma, low-pressure symptoms and valve damage). RESULTS: Patients underwent a total of 29 adjustments to below 5cmH2O. The mean valve opening pressure after the first adjustment was 2.5cmH2O and the mean opening pressure after the second adjustment was 1cmH2O. Overall, outcome after adjustment included 26% no change, 48% improvement and 26% deterioration clinically. One patient (4%) suffered traumatic subdural haematoma that resolved with increasing valve pressure to 20cmH2O. There was no valve damage or low-pressure symptoms after adjustment. CONCLUSION: This study found that lowering the opening pressure of the proGAV shunt system to below 5cmH2O results in clinical improvement and does not significantly increase the complication rate in iNPH patients.

Systematic review of the outcome of shunt surgery in idiopathic normal-pressure hydrocephalus.

INTRODUCTION: Early surgical series of shunt insertion for idiopathic normal-pressure hydrocephalus reported a low rate of short-term improvement with a relatively high rate of mortality and morbidity; subsequently shunt insertion was recommended for patients in whom there is favourable risk-to-benefit ratio. METHODS: Bibliographic search for studies that objectively assessed the outcome following shunt insertion in idiopathic normal-pressure hydrocephalus was done; the aim was to estimate the outcome of shunt insertion in terms of improvement rates and associated mortality and morbidity. RESULTS: A total of 64 studies of 3,063 patients were reviewed. Positive improvement following shunt insertion was reported in an average of 71 % of patients with an average 1 % mortality. Results from studies published in the last 5 years showed 82 % improvement following shunt insertion, mortality of 0.2 %, and combined common complications rate of 8.2 %. CONCLUSION: When patients are properly selected, shunt insertion is a safe and effective management of idiopathic normal-pressure hydrocephalus with a prolonged positive outcome.

An unusual anatomic and geographic location of primary germinoma of the fourth ventricle.

Intracranial germinoma is most commonly found in the pineal and suprasellar regions. The medulla oblongata and fourth ventricle are rare sites of primary germinoma, with only 12 previous patients reported, all from the Far East. To our knowledge, we report the first patient from Europe. A 25-year-old female of Afro-Caribbean origin presented with several weeks of worsening migraines, dizziness, tachycardia and veering to the right whilst walking. MRI revealed a lesion in the fourth ventricle, which was treated with surgical debulking and post operative radiotherapy. Two months following completion of radiotherapy, MRI showed almost complete resolution of the enhancing disease within the primary tumour area and no intraspinal pathological enhancement. This patient highlights the importance of considering germinoma in the differential diagnosis of all medullary masses with extension into the fourth ventricle irrespective of geographic location.

Early single centre experience of flow diverting stents for the treatment of cerebral aneurysms.

INTRODUCTION: The flow diverting stent (FDS) is a relatively new endovascular therapeutic tool specifically designed to reconstruct the parent artery and divert blood flow along the normal anatomical course and away from the aneurysm neck and dome. METHODS: Retrospective review of prospectively built clinical and imaging database of patients treated with FDS at the National Hospital for Neurology and Neurosurgery, Queen Square, London, UK was done. RESULTS: Between 18/03/2008 and 10/11/2011, 80 patients underwent 84 FDS insertion procedures for various indications. Mean duration of clinical follow-up was 11.3 ± 9.3 months and of imaging follow-up was 10.6 ± 9.3 months. Sixty-seven had anterior circulation aneurysms while 17 had posterior circulation aneurysms. Seven (8.3%) patients died (two probably not related, giving a procedure-related mortality of 5.9%), eight had permanent new deficit (9.5%), 20 had transient deficit (23%) and 49 (58%) had no complications. There was a trend towards bad outcome with larger posterior circulation aneurysms. Angiographic follow-up showed 38% cure rate at 6 months and 61% at 12 months. CONCLUSION: FDS should only be used following multidisciplinary discussion in selected patients. Further data is required regarding long-term safety, efficacy and indications.

Early years neurosurgical training in the era of the European Working Time Directive.

The past decade has seen significant changes to the face of neurosurgical training in the United Kingdom, driven in part by an increasing focus on patient safety and the introduction of Modernising Medical Careers and the European Working Time Directive (EWTD). Recent reforms to neurosurgical training over the past few years have resulted in creation of an 8-year 'run-through' training programme. In this programme, early years (ST1 and ST2) trainees often lack dedicated time for elective theatre lists and outpatient clinics. Further, any time spent in theatre and clinics is often with different teams. Here we describe a training model for early years trainees at the National Hospital for Neurology and Neurosurgery, who are given the responsibilities traditionally associated with a more senior trainee including dedicated weekly theatre and clinic time under the supervision of a single consultant, in addition to out of hours experience. The advantages and considerations for implementing this model are discussed, including the benefit of guidance under a single consultant in the early stages of training, along with key educational concepts necessary for understanding its utility. We feel that this is an effective model for junior neurosurgical training in the EWTD era, expediting the trainee's development of key technical and non-technical skills, with potentially significant rewards for patient, trainee and trainer. National implementation of this model should be considered.

Cerebral venous system and anatomical predisposition to high-altitude headache.

OBJECTIVE: As inspired oxygen availability falls with ascent to altitude, some individuals develop high-altitude headache (HAH). We postulated that HAH results when hypoxia-associated increases in cerebral blood flow occur in the context of restricted venous drainage, and is worsened when cerebral compliance is reduced. We explored this hypothesis in 3 studies. METHODS: In high-altitude studies, retinal venous distension (RVD) was ophthalmoscopically assessed in 24 subjects (6 female) and sea-level cranial magnetic resonance imaging was performed in 12 subjects ascending to 5,300m. Correlation of headache burden (summed severity scores [0-4]≤24 hours from arrival at each altitude) with RVD, and with cerebral/cerebrospinal fluid (CSF)/venous compartment volumes, was sought. In a sea-level hypoxic study, 11 subjects underwent gadolinium-enhanced magnetic resonance venography before and during hypoxic challenge (fraction of inspired oxygen=0.11, 1 hour). RESULTS: In the high-altitude studies, headache burden correlated with both RVD (Spearman rho=0.55, p=0.005) and with the degree of narrowing of 1 or both transverse venous sinuses (r=-0.56, p=0.03). It also related inversely to both the lateral+third ventricle summed volumes (Spearman rho=-0.5, p=0.05) and pericerebellar CSF volume (r=-0.56, p=0.03). In the hypoxic study, cerebral and retinal vein engorgement were correlated, and rose as the combined conduit score fell (a measure of venous outflow restriction; r=-0.66, p<0.05 and r=-0.75, p<0.05, respectively). INTERPRETATION: Arterial hypoxemia is associated with cerebral and retinal venous distension, whose magnitude correlates with HAH burden. Restriction in cerebral venous outflow is associated with retinal distension and HAH. Limitations in cerebral venous efferent flow may predispose to headache when hypoxia-related increases in cerebral arterial flow occur.

The prognostic value of brain extracellular fluid nitric oxide metabolites after traumatic brain injury.

BACKGROUND: Nitric oxide (NO) is a compound with both protective and damaging effects on neurons. Quantification of NO metabolites in humans is limited by sample contamination with blood. In vivo cerebral microdialysis may offer an alternative approach as sampling of extracellular fluid (ECF) adjacent to neurons becomes possible. We investigate the prognostic value of brain ECF NO metabolites in patients with traumatic brain injury (TBI). METHODS: A prospective case cohort of 195 ECF samples collected from 11 cases over 4 days following TBI was collected. Nitrate and nitrite concentrations ([NO x ]) were quantified using a vanadium-based colorimetric assay. RESULTS: Early ECF [NO x ] (<48 h post TBI) were significantly higher in non-survivors (median 59.2 µmol/l, n = 7) compared to survivors (23.3 µmol/l, n = 4) (P = 0.04). Late (48-96 h) ECF [NO x ] remained higher in non-survivors (47.9 µmol/l) compared to survivors (23.0 µmol/l) but this was not significant (P = 0.29). Receiver operator characteristic analysis shows an optimized cutoff level for ECF [NO x ] of 26.5 µmol/l measured <48 h post TBI for predicting non-survival (sensitivity 100%, specificity 75%). CONCLUSION: Early ECF NO x concentrations are of prognostic value after TBI. ECF NO x may be a useful biomarker for treatment trials targeted at nitric oxide metabolism.

Conservative versus surgical management of idiopathic normal pressure hydrocephalus: a prospective double-blind randomized controlled trial: study protocol.

There is no level I evidence to indicate whether placement of a shunt is effective in the management of idiopathic normal pressure hydrocephalus (INPH), because no trial has as yet compared the placement of a shunt versus no shunt in a randomized controlled manner. We started recruiting patients into a prospective double-blind randomized controlled study aiming to provide class I evidence supporting or refuting the role of surgical management in INPH. Inclusion criterion was the diagnosis of probable INPH plus objective improvement of walking speed following 72 h of extended lumbar drainage. Patients with concomitant Alzheimer's disease or vascular dementia were excluded. All patients included in the trial were to have a shunt placed with proGAV(®) adjustable valve. Patients were randomly assigned into two groups: group A was to have the shunt immediately adjusted to function, and group B was to have the shunt valve adjusted to the highest setting for 3 months then adjusted to function. Assessment of gait, cognitive function, and urinary symptoms were done before shunt insertion and at 3 months. Primary end point was to be an improvement in gait. Secondary end points were improvement in mental function or urinary function and incidence of complications. Final results are expected mid 2011.

Secondary normal pressure hydrocephalus in a patient with isolated frontal dilatation--an insight into pathophysiology?

Current theories of the pathophysiology of normal pressure hydrocephalus suggest the classical symptoms are a consequence of disruption of normal frontal function. We present the case of a 70-year-old patient with an isolated, frontal dilatation of his lateral ventricles in the presence of a complete triad as supportive of these theories.

Cognitive, biochemical, and imaging profile of patients suffering from idiopathic normal pressure hydrocephalus.

INTRODUCTION: It has still not been clearly established whether the cognitive deficits of idiopathic normal pressure hydrocephalus (iNPH) are caused by a disturbance in cerebrospinal fluid (CSF) dynamics or an underlying metabolic disturbance. OBJECTIVE: To identify the possible associations between biochemical markers, the neuroimaging characteristics, and cognitive deficits of patients undergoing investigations for possible iNPH. METHODS: A CSF sample obtained during a lumbar puncture from 10 patients with iNPH was analyzed for several biochemical markers (lactate, 8-isoprostane, vascular endothelial growth factor [VEGF], neurofilament heavy protein, glial fibrillary acidic protein, amyloid beta 1-42, and total tau). All patients underwent a battery of neuropsychological testing and imaging as part of their selection process for their suitability for CSF diversion surgical procedure. Volumetric analysis of imaging was carried out measuring the ventricular volume (VV), intracranial volume (ICV), periventricular lucencies, deep white matter hyperintensities, and white matter (WM) volume, as well as their ratios. RESULTS: A significant negative correlation of preoperative symptom duration and total tau levels (R = -0.841, P = .002) was found. There was a significant positive correlation (R = 0.648, P = .043) between the levels of VEGF and the VV/ICV ratio. There was a significant positive correlation of the levels of glial fibrillary acidic protein and the VV/deep white matter hyperintensities ratio (R = 0.828, P = .006). A significant negative correlation was observed between the levels of neurofilament heavy protein and the VV/ICV ratio (R = -0.657, P = .039) and the WM volume (R = -0.778, P = .023). Lactate levels were lower for patients performing in the normal range on the Recognition Memory Test for faces. Patients who performed better in the Recognition Memory Test words test had higher ICV volumes. All the patients in this study showed below normal performance when the subcortical function was assessed. CONCLUSION: The positive correlation of VEGF with the severity of ventriculomegaly may indicate that this is because of the transmantle pressure gradient; this response may not be because of hypoxia but represents an attempt at neuroregeneration. The degree of reactive gliosis correlates inversely with the severity of WM lesions. Neuronal degeneration is negatively correlated with the volume of the WM in these patients. The small association of volumetry and the cognitive profile of these patients may be consistent with a direct biochemical disturbance being responsible for the cognitive deficit observed. Ongoing studies with set protocols for neuropsychological assessment and volumetric analysis are warranted to further elucidate on the preliminary results of the current study.

Natural history of idiopathic normal-pressure hydrocephalus.

Natural history of idiopathic normal-pressure hydrocephalus (INPH) is not clear. We performed a literature search for studies that looked into the outcome of unshunted INPH patients trying to answer the following questions: Do all INPH patients deteriorate without shunt? If yes, at what rate? Do some NPH patients improve without shunt? If yes, to what extent? Six studies objectively described the outcome of 102 INPH patients. Result shows that without surgery, most INPH patients had measurable deterioration as early as 3 months following initial assessment. A small number of patients might improve without shunt, however the extent of improvement is not clear. The homogeneity of the findings of the cohort studies provided high evidence supporting the rule of shunt surgery in INPH patients.

Use of cerebrospinal fluid amyloid-ß and total tau protein to predict favorable surgical outcomes in patients with idiopathic normal pressure hydrocephalus.

OBJECT: The prognostic value of CSF biomarkers in patients with idiopathic normal pressure hydrocephalus (iNPH) has not been adequately studied to date. The aim of this study was to identify CSF markers of favorable surgical outcome in patients with iNPH undergoing the insertion of a ventriculoperitoneal shunt. METHODS: Ventricular CSF was collected intraoperatively from 22 patients with iNPH and enzyme-linked immunosorbent assay was used to analyze the levels of amyloid-ß 1-42 (Aß(1-42)) and total tau protein. The Black grading scale was used to assess outcomes at 6 months. Receiver operating characteristic (ROC) curves were obtained and discriminant function analysis was undertaken to provide sensitivity and specificity figures for each marker as well as their combination. RESULTS: The mean age of the patients was 71.45 years (± 9.5 years [SD]). Follow-up was achieved in 21 patients. Seventeen patients had a favorable outcome and 4 patients had unfavorable outcome at 6 months. An Aß(1-42) level of 180 pg/ml had a sensitivity of 35% and a specificity of 20% for predicting a favorable outcome at 6 months. A total tau level of 767 pg/ml will have a sensitivity of 17% and a specificity of 20% for predicting a favorable outcome at 6 months. A combination of Aß(1-42) and total tau levels predicted favorable outcomes with a sensitivity of 80% and specificity of 82.4%. CONCLUSIONS: In this pilot study a combination of Aß(1-42) levels and total tau protein levels predicted favorable surgical outcomes at 6 months with adequate accuracy to be of clinical use. Further study in a larger group with longer follow-up is warranted.

Is there a difference in outcomes of patients with idiopathic intracranial hypertension with the choice of cerebrospinal fluid diversion site: a single centre experience.

UNLABELLED: The visual and headache outcomes in patients with idiopathic intracranial hypertension (IIH) undergoing cerebrospinal fluid diversion with a lumboperitoneal (LPS) or ventriculoperitoneal shunting (VPS) have not been well reported. The aims of this study were to: (a) to assess outcomes of CSF diversion in IIH, (b) to understand influence of the type of shunt in outcomes, and (c) to understand factors predisposing in shunt failure. METHODS: The medical records of 34 patients who underwent cerebrospinal fluid diversion (CSFD) between 1996 and 2007 were retrieved and epidemiological and clinical data was collected. RESULTS: The mean age was 35 (±7.9) years. Thirty-four patients underwent 63 shunt placements in total. 85% follow-up was achieved. The mean follow-up for the entire group was 28.9 (±31.8) months. Headaches improved more than visual disturbances. There was no significant difference between the groups that received a VPS and those receiving an LPS in both headache and visual outcomes. The rate of complications was 20.5% and the need for revision was 35% for the whole group. Patients with LPS suffered more complications and first time revisions than patients with VPS. No factor recorded could predict the need for revision or final outcomes. The shunts of patients receiving a VPS tend to survive longer than those receiving primarily an LPS, however the difference is not statistically significant. CONCLUSIONS: Predicting which patients will improve is not possible at present. The influence of site diversion is not critical but patients with VPS have less complications and revisions than those receiving a LPS.

Use of the proGAV shunt valve in normal-pressure hydrocephalus.

BACKGROUND: Overdrainage is a common complication associated with shunt insertion in normal-pressure hydrocephalus (NPH) patients. Using adjustable valves with antigravity devices has been shown to reduce its incidence. The optimal starting setting of an adjustable shunt valve in NPH is debatable. OBJECTIVE: To audit our single-center practice of setting adjustable valves. METHODS: We performed a retrospective review of clinical records of all NPH patients treated in our unit between 2006 and 2009 by the insertion of shunts with a proGAV valve, recording demographic and clinical data, shunt complications, and revision rates. Radiological reports of postoperative follow-up computed tomography scans of the brain were reviewed for detected subdural hematomas. RESULTS: A proGAV adjustable valve was inserted in 50 probable NPH patients between July 2006 and November 2009. Mean ± SD age was 76 ± 7 years. Mean follow-up was 15 months. The initial shunt setting was 6 ± 3 cm H2O, and the final setting was 4.9 ± 1.9 cm H2O. Nineteen patients required 24 readjustment procedures (readjustment rate, 38%; readjustment number, 0.48 times per patient). One patient (2%) developed delayed bilateral subdural hematoma after readjustment of his shunt valve setting as an outpatient. CONCLUSION: Starting with a low opening pressure setting on a proGAV adjustable shunt valve does not increase the chances of overdrainage complications and reduces the need for repeated readjustments.

Evans' index revisited: the need for an alternative in normal pressure hydrocephalus.

BACKGROUND: The international guidelines for the diagnosis of normal pressure hydrocephalus (NPH) define ventricular enlargement as Evans' index greater than 0.3. OBJECTIVE: To establish whether there is a correlation between Evans' index and ventricular volume (VV) in NPH and whether choosing different planes for the measurements could produce significantly different results. METHODS: Pre-shunt insertion, thin-section CT scans of the brains of 10 patients with shunt-responsive NPH were reviewed retrospectively, measuring Evans' index, frontal horn index, VV, and total intracranial volume (ICV). The ventricular/intracranial volume index (VV/ICV) was calculated. Correlation between each of the linear indices and VV and VV/ICV was done. RESULTS: Significant differences were found in the index values calculated at different planes. The frontal horn index at a plane 16 mm parallel to the anterior commissure-posterior commissure (AC-PC) plane showed best correlation with VV and VV/ICV (r: 0.658 and 0.587, respectively). Evans' index, also obtained at a plane 16 mm parallel to the AC-PC plane, showed best correlation with VV and VV/ICV (r: 0.619 and 0.498, respectively). CONCLUSION: Evans' index value can vary significantly in a patient with NPH, depending on the level of the brain CT scan image at which the frontal horns and maximal inner skull diameters are measured. Evans' index is not an ideal method for estimating the VV in NPH patients. Volumetric measurements represent the logical accurate estimate of true ventricular size as well as the size of the other intracranial compartments.

Working towards patient oriented outcome assessment in normal pressure hydrocephalus, what is the most important?

OBJECTIVE: To date, there is no standard outcome assessment scale for shunt treatment in normal pressure hydrocephalus (NPH). In designing such scale, the relative weight of each of the common presentations of the condition from the patient's or his/her carer's point of view should be taken into consideration. METHODS: A questionnaire was sent to 24 patients treated for NPH and their family/carer, assessing the patient and carer categorization of the preoperative main complaint, the weight they give to each of the common presentations of NPH and their satisfaction with treatment. RESULTS: Twenty-two patients and 20 carers replied. Gait disturbance was the main complaint from both patient's (86%) and carer's (75%) point of view. Similarly, gait disturbance was considered as the most important problem that needs improvement by both patients (77%) and carers (65%). Incontinence was considered the second most important area by 11 (50%) patients and seven (35%) carers. When asked to quantify their satisfaction out of 10, patients had a mean of 7.2 while carers gave a mean of 7.5. Comparing subjective perspective of improvement with that of objective improvement on 10 m walking test and neuropsychological assessment, all patients who improved objectively were perceived as improved to a satisfactory degree by carers. CONCLUSION: Walking/balance should be given far greater weight than other components of the NPH triad in future outcome assessment scales in accordance with patient/family perception.

Rostrocaudal dynamics of CSF biomarkers.

The rostrocaudal gradient (RCG) of markers present in cerebrospinal fluid (CSF) has not been studied adequately due to lack of appropriate control populations and ethical restrictions. The aim of this study is to understand the rostrocaudal gradient of CSF biomarkers. We contacted a study comparing CSF levels of seven biomarkers from cisternal (rostral) and lumbar (caudal) CSF obtained from patients with trigeminal neuralgia and tension-type headache. The RCGs of CSF/serum albumin ratio, 8-isoprostane. GFAP, total tau and beta amyloid protein were higher than one. The RCGs of lactate, VEGF and the heavy chain of neurofilament protein were lower than one. The study provides new values for several commonly examined markers of cisternal CSF. Knowledge of the RCG gradient of different CSF markers is important in interpreting studies reporting ventricular CSF values.