Ventriculo-atrial shunt in idiopathic intracranial hypertension.

PURPOSE: CSF diversion  is a recognised intervention in idiopathic intracranial hypertension (IIH), particularly in the presence of vision-threatening papilledema. Although ventriculo-atrial (VA) shunt insertion is a routine neurosurgical procedure, ventriculoperitoneal and lumboperitoneal shunts have been mostly used in this particular indication. This study aims to look at a single centre's experience with VA shunts in idiopathic intracranial hypertension (IIH). METHODS: Retrospective case series with a review of electronic records over a 10-year period; exclusion criteria were duplication of same shunt insertion, no VA shunt insertion, paediatric patients and indication other than IIH. Notes were reviewed for demographics, shunt survival (defined by time prior to revision) and reasons for revision. RESULTS: Eight VA shunt procedures were identified in 6 patients (mean age at insertion 34 ± 10 years) with a mean follow-up of 58 ± 25 months. All shunts were secondary procedures; 2 revisions from lumbo-pleural, 2 from ventriculopleural, 2 from ventriculoatrial and one each from ventriculoperitoneal and combined lumbo-/ventriculoperitoneal. At 50 months, 75% of VA shunts had survived, compared to only 58.3% of VPleural shunts in patients with IIH. Revisions were required due to acute intracranial bleed (1 case)-revised at day 1, and thrombus at distal site (1 case)-revised at day 57. Both shunts were later reinserted. From the latest clinic letters, all patients had their treatment optimised with this procedure, although only two patients had documented resolved papilloedema post-procedure. CONCLUSIONS: Ventriculo-atrial shunts are a safe and efficacious alternative option for CSF diversion in IIH. In this series, only 1 shunt was revised for a VA shunt-specific complication.

Patient-specific automated cerebrospinal fluid pressure control to augment spinal wound closure: a case series using the LiquoGuard®.

OBJECTIVE: Spinal cerebrospinal fluid (CSF) leaks are common, and their management is heterogeneous. For high-flow leaks, numerous studies advocate for primary dural repair and CSF diversion. The LiquoGuard7® allows automated and precise pressure and volume control, and calculation of patient-specific CSF production rate (prCSF), which is hypothesized to be increased in the context of durotomies and CSF leaks. METHODS: This single-centre illustrative case series included patients undergoing complex spinal surgery where: 1) a high flow intra-operative and/or post-operative CSF leak was expected and 2) lumbar CSF drainage was performed using a LiquoGuard7®. CSF diversion was tailored to prCSF for each patient, combined with layered spinal wound closure. RESULTS: Three patients were included, with a variety of pathologies: T7/T8 disc prolapse, T8-T9 meningioma, and T4-T5 metastatic spinal cord compression. The first two patients underwent CSF diversion to prevent post-op CSF leak, whilst the third required this in response to post-op CSF leak. CSF hyperproduction was evident in all cases (mean >/=140ml/hr). With patient-specific CSF diversion regimes, no cases required further intervention for CSF fistulae repair (including for pleural CSF effusion), wound breakdown or infection. CONCLUSIONS: Patient-specific cerebrospinal fluid drainage may be a useful tool in the management of high-flow intra-operative and post-operative CSF leaks during complex spinal surgery. These systems may reduce post-operative CSF leakage from the wound or into adjacent body cavities. Further larger studies are needed to evaluate the comparative benefits and cost-effectiveness of this approach.

The benefits of automated CSF drainage in normal pressure hydrocephalus.

BACKGROUND: The commonly used cerebrospinal fluid (CSF) drainage system remains the manual drip-chamber drain. The LiquoGuard (Möller Medical GmbH, Germany) is an automated CSF management device with dual functionality, measuring intracranial pressure and automatic pressure- or volume-led CSF drainage. There is limited research for comparison of devices, particularly in the neurosurgical field, where it has potential to reshape care. OBJECTIVE: This study aims to compare manual drip-chamber drain versus LiquoGuard system, by assessing accuracy of drainage, associated morbidity and impact on length of stay. METHOD: Inclusion criteria consisted of suspected normal pressure hydrocephalus (NPH) patients undergoing extended lumbar drainage. Patients were divided into manual drain group versus automated group. RESULTS: Data was analysed from 42 patients: 31 in the manual group versus 11 in the LiquoGuard group. Volumetric over-drainage was seen in 90.3% (n = 28) versus 0% (p < 0.05), and under-drainage in 38.7% (n = 12) versus 0% (p < 0.05), in the manual and automatic group, respectively. Symptoms of over-drainage were noted in 54.8% (n = 17) of the manual group, all of which had episodes of volumetric over-drainage, versus 18.2% (n = 2) in automated group, of which neither had actual over-drainage (p < 0.05). Higher over-drainage symptoms of manual drain is likely due to increased fluctuation of CSF drainage, instead of smooth CSF drainage seen with LiquoGuard system. An increased length of stay was seen in 38.7% (n = 12) versus 9% (n = 1) (p < 0.05) in the manual and LiquoGuard group, respectively. CONCLUSION: The LiquoGuard device is a more superior way of CSF drainage in suspected NPH patients, with reduced morbidity and length of stay.

The initial intracranial pressure spike phenomenon.

BACKGROUND: Elective use of intraparenchymal intracranial pressure (ICP) monitoring is a valuable resource in the investigation of hydrocephalus and other cerebrospinal fluid disorders. Our preliminary study aims to investigate ICP changes in the immediate period following dural breach, which has not yet been reported on. METHOD: This is a prospective cohort study of patients undergoing elective ICP monitoring, recruited between March and May 2022. ICP readings were obtained at opening and then at 5-min intervals for a 30-min duration. RESULTS: Ten patients were recruited, mean age 45 years, with indications of a Chiari malformation (n = 5), idiopathic intracranial hypertension (n = 3) or other ICP-related pathology (n = 2). Patients received intermittent bolus sedation (80%) vs general anaesthesia (20%). Mean opening pressure was 22.9 mmHg [± 6.0], with statistically significant decreases present every 5 min, to a total reduction of 15.2 mmHg at 20 min (p = < 0.0001), whereafter the ICP plateaued with no further statistical change. DISCUSSION: Our results highlight an intracranial opening pressure 'spike' phenomenon. This spike was 15.2 mmHg higher than the plateau, which is reached at 20 min after insertion. Several possible causes exist which require further research in larger cohorts, including sedation and pain response. Regardless of causation, this study provides key information on the use of ICP monitoring devices, guiding interpretation and when to obtain measurements.

Cerebrospinal fluid production rate in various pathological conditions: a preliminary study.

INTRODUCTION: The cerebrospinal fluid (CSF) production rate in humans is not clearly defined but is estimated to be 18-24 ml/h (Trevisi et al Croat Med J 55(4):377-387 (24); Casey and Vries Childs Nerv Syst 5(5):332-334 (8)). A frequent clinical observation is that patients often drain higher volumes of CSF than can be explained by the assumed 'normal' CSF production rate (PRcsf). In the National Hospital for Neurology and Neurosurgery PRcsf was recorded in a variety of common neurosurgical pathologies using LiquoGuard7, an automated peristaltic pump that accurately controls CSF drainage and maintains a pre-set CSF pressure. METHODS: A prospective observational study was performed from September 2021 onwards, on all patients in the National Hospital for Neurology and Neurosurgery who required CSF drainage as part of their ongoing treatment. The external drain was connected to a LiquoGuard7 pump (Möller Medical GmbH, Fulda, Germany), and the internal software of LiquoGuard7 was used to measure PRcsf. Statistical analysis used SPSS (version 25.0, IBM) by paired t test, comparing measured rates to hypothetical 'normal' CSF production rates calculated and published by Ekstedt (16-34ml/h) (Ekstedt J Neurol Neurosurg Psychiatry 41(4):345-353 (14)), assuming a similar distribution. RESULTS: PRcsf was calculated in 164 patients. Suspected normal pressure hydrocephalus (n=41): PRcsf of 79ml/h±20SD (p<0.0001). Post-surgical CSF leak (n=26): PRcsf of 90ml/h±20SD (p<0.0001). Subarachnoid haemorrhage (n=34): PRcsf of 143ml/h±9SD (p<0.0001). Intracerebral haemorrhage (n=22): PRcsf of 137ml/h±20SD (p<0.0001). Spinal lesions (n=7): PRcsf of 130ml/h±20SD (p<0.0032). Pituitary adenomas (n=10): PRcsf of 29 ml/h±9SD (p<0.049). Idiopathic intracranial hypertension (n=15): PRcsf of 86ml/h±10SD (p<0.0001). Decompensated long-standing overt ventriculomegaly (n=4): PRcsf of 65ml/h±10SD (p<0.0001). Cerebral infection (n=5): PRcsf of 90ml/h±20SD (p<0.0001). CONCLUSION: Net CSF production rate may be higher than expected in many conditions, as measured with new device LiquoGuard7 through the study of net flow rate, which may have implications for clinical decisions on CSF diversion. The conventional understanding of CSF production and circulation does not explain the findings of this study. More extensive studies are needed to validate this technique.

ICP during head movement: significance of the venous system.

BACKGROUND: It is thought that the internal jugular veins (IJV) are the primary route for cranial venous outflow in supine position and the vertebral venous plexus when upright. Previous studies have noted a greater increase in intracranial pressure (ICP) when subjects turn their head in one direction compared to the other, but no clear cause had been investigated. We hypothesised that in the supine position, head turning and consequently obstructing the IJV draining the dominant transverse sinus (TVS) would lead to a greater rise in ICP compared to turning to the non-dominant side. METHODS: A prospective study in a large-volume neurosurgical centre. Patients undergoing continuous ICP monitoring as part of their standard clinical management were recruited. Immediate ICP was measured in different head positions (neutral, rotated to the right and left) when supine, seated, and standing. TVS dominance was established by consultant radiologist report on venous imaging. RESULTS: Twenty patients were included in the study, with a median age of 44 years. Venous system measurements revealed 85% right-sided vs 15% left-sided dominance. Immediate ICP rose more when head turning from neutral to the dominant TVS (21.93mmHg ± 4.39) vs non-dominant side (16.66mmHg ± 2.71) (p= <0.0001). There was no significant relationship in the sitting (6.08mmHg ± 3.86 vs 4.79mmHg ± 3.81, p = 0.13) or standing positions (8.74mmHg ± 4.30 vs 6.76mmHg ± 4.14, p =0.07). CONCLUSION: This study has provided further evidence that the transverse venous sinus to internal jugular system pathway is the likely primary venous drainage when supine; and quantified its effect when head turning on ICP. It may guide patient-specific nursing care and advice.

A case of recurrent flight-induced cerebrospinal fluid shunt overdrainage.

Shunted patients often complain of headaches after flights. The effect of air travel on shunt systems is unknown. We describe the case of a patient with longstanding hydrocephalus, who suffered flight-induced clinical deterioration and shunt overdrainage in two independent occasions. The patient, clinically stable for 1.5 and 5 years before each episode, reported severe headaches starting during the descent stages of the air travel. On both occasions, brain MRI imaging demonstrated pronounced ventricular size reduction. This case suggests that flight-induced shunt overdrainage can occur and should be suspected in patients with prolonged headaches and/or clinical deterioration triggered by air travel.

External ventricular drain management in subarachnoid haemorrhage: a systematic review and meta-analysis.

External ventricular drainage (EVD) is one of the most commonly performed neurosurgical procedures. Despite this, the optimal drainage and weaning strategies are still unknown. This PRISMA-compliant systematic review and meta-analysis analysed the outcomes of patients undergoing EVD procedures, comparing continuous versus intermittent drainage and rapid versus gradual weaning. Four databases were searched from inception to 01/10/2020. Articles reporting at least 10 patients treated for hydrocephalus secondary to subarachnoid haemorrhage were included. Other inclusion criteria were the description of the EVD drainage and weaning strategies used and a comparison of continuous versus intermittent drainage or rapid versus gradual weaning within the study. Random effect meta-analyses were used to compare functional outcomes, incidence of complications and hospital length of stay. Intermittent external CSF drainage was associated with lower incidence of EVD-related infections (RR = 0.20, 95% CI 0.05-0.72, I-squared = 0%) and EVD blockages compared to continuous CSF drainage (RR = 0.45, 95% CI 0.27-0.74, I-squared = 0%). There was no clear advantage in using gradual EVD weaning strategies compared to rapid EVD weaning; however, patients who underwent rapid EVD weaning had a shorter hospital length of stay (SMD = 0.34, 95% CI 0.22-0.47, I-squared = 0%). Intermittent external CSF drainage after SAH is associated with lower incidence of EVD-related infections and EVD blockages compared to continuous CSF drainage. Patients who underwent rapid EVD weaning had a shorter hospital length of stay and there was no clear clinical advantage in using gradual weaning.

Neuronavigation-assisted bedside placement of bolt external ventricular drains in the intensive care setting: a technical note.

BACKGROUND: The insertion of bolt external ventricular drains (EVD) on the intensive care unit (ICU) has enabled rapid cranial cerebrospinal fluid (CSF) diversion. However, bolt EVDs tend to be perceived as a more challenging technique, particularly when dealing with small ventricles or when there is midline shift distorting the ventricular morphology. Furthermore, if neuronavigation guidance is felt to be necessary, this usually assumes a transfer to an operating theatre. In this technical note, we describe the use of electromagnetic neuronavigation for bolt EVD insertion on the ICU and assess the protocol's feasibility and accuracy. METHODS: Case series of neuronavigation-assisted bolt EVD insertion in ICU setting, using Medtronic Flat Emitter for StealthStation EM. RESULTS: Neuronavigation-guided bolt EVDs were placed at the bedside in n = 5 patients on ICU. Their widest frontal ventricular horn diameter in the coronal plane ranged from 11 to 20 mm. No procedural complications were encountered. Post-procedural CT confirmed the optimal placement of the EVDs. CONCLUSIONS: Electromagnetic neuronavigation is feasible at the ICU bedside and can assist the insertion of bolt EVDs in this setting. The preference for a bolt EVD to be inserted in ICU-as is standard practice at this unit-should not prohibit patients from benefitting from image guidance if required.

Long-Term Outcomes of Occipital Nerve Stimulation for New Daily Persistent Headache With Migrainous Features.

OBJECTIVES: New daily persistent headache (NDPH) is a subset of chronic headache where the pain is continuous from onset. Phenotypically it has chronic migraine or chronic tension type features. NDPH is considered to be highly refractory. Occipital nerve stimulation (ONS) has been used for treatment of refractory chronic migraine but there are no specific reports of its use for NDPH with migrainous features. MATERIALS AND METHODS: Nine patients with NDPH with migrainous features were identified as having had ONS implants between 2007 and 2014 in a specialist unit with experience of using ONS in chronic migraine. Moderate to severe headache days were compared at baseline and follow-up. A positive response was defined as at least 30% reduction in monthly moderate to severe headache days. RESULTS: Patients had suffered NDPH for a median of 8 years (range 3-16 years) and had failed a median of 11 previous treatments (range 8-15). After a median follow-up of 53 months (range 27-108 months), only a single patient showed a positive response to ONS. At no point did the cohort as a whole show any change in monthly moderate to severe headache days or disability scores. CONCLUSION: Our experience suggests that ONS is not effective in the treatment of NDPH with migrainous features even in centers with experience in treating chronic migraine with ONS. The difference in response rates of chronic migraine and NDPH with migrainous features supports the concept of a different pathophysiology to the two conditions.

Ultra-low-pressure hydrocephalic state in NPH: benefits of therapeutic siphoning with adjustable antigravity valves.

BACKGROUND: Idiopathic normal-pressure hydrocephalus (NPH) is a condition of the elderly treated by ventriculoperitoneal shunt (VP) insertion. A subset of NPH patients respond only temporarily to shunt insertion despite low valve opening pressure. This study aims to describe our experience of patients who benefit from further CSF drainage by adding adjustable antigravity valves and draining CSF at ultra-low pressure. METHODS: Single-centre retrospective case series of patients undergoing shunt valve revision from an adjustable differential pressure valve with fixed antigravity unit to a system incorporating an adjustable gravitational valve (Miethke proSA). Patients were screened from a database of NPH patients undergoing CSF diversion over 10 consecutive years (April 2008-April 2018). Clinical records were retrospectively reviewed for interventions and clinical outcomes. RESULTS: Nineteen (10F:9M) patients underwent elective VP shunt revision to a system incorporating an adjustable gravitational valve. Mean age 77.1 ± 7.1 years (mean ± SD). Eleven patients (58%) showed significant improvement in walking speed following shunt revision. Fourteen patients/carers (74%) reported subjective improvements in symptoms following shunt revision. CONCLUSIONS: Patients presenting symptoms relapse following VP shunting may represent a group of patients with ultra-low-pressure hydrocephalus, for whom further CSF drainage may lead to an improvement in symptoms. These cases may benefit from shunt revision with an adjustable gravitational valve, adjustment of which can lead to controlled siphoning of CSF and drain CSF despite ultra-low CSF pressure.

Paradoxical response of intracranial pressure to shunt valve setting adjustments.

BACKGROUND: The hydrodynamics of cerebrospinal fluid shunts have been described in vitro; however, knowledge on the response of intracranial pressure (ICP) to valve settings adjustments in vivo is limited. This study describes the effect of adjusting the shunt valve setting on ICP in a cohort of patients with complex symptom management. METHOD: Single-centre retrospective observational study. Patients who underwent ICP-guided valve setting adjustments during 24-h continuous ICP monitoring, between 2014 and 2019, were included. Patients with suspected shunt malfunction were excluded. Median night ICP before and after the valve adjustments were compared (Δ night ICP). The responses of ICP to valve adjustment were divided into 3 different groups as follows: expected, paradoxical and no response. The frequency of the paradoxical response and its potential predicting factors were investigated. RESULTS: Fifty-one patients (37 females, 14 males, mean age 38 years) receiving 94 valve setting adjustments met the study inclusion criteria. Patients' underlying conditions were most commonly hydrocephalus (47%) or idiopathic intracranial hypertension (43%). The response of ICP to valve setting adjustments was classified as 'expected' in 54 cases (57%), 'paradoxical' in 17 cases (18%) and 'no effect' (Δ night ICP < 1 mmHg) in 23 cases (24%). There was a significant correlation between the Δ night ICP and the magnitude of valve setting change in both the investigated valves (Miethke ProGAV, p = 0.01 and Medtronic Strata, p = 0.02). CONCLUSIONS: Paradoxical ICP changes can occur after shunt valve setting adjustments. This observation should be taken into account when performing ICP-guided valve adjustments and is highly relevant for the future development of "smart" shunt systems.

Predictors of response to occipital nerve stimulation in refractory chronic headache.

Background Occipital nerve stimulation is a promising treatment for refractory chronic headache disorders, but is invasive and costly. Identifying predictors of response would be useful in selecting patients. We present the results of an open-label prospective cohort study of 100 patients (35 chronic migraine, 33 chronic cluster headache, 20 short-lasting unilateral neuralgiform headache attacks and 12 hemicrania continua) undergoing occipital nerve stimulation, using a multivariate binary regression analysis to identify predictors of response. Results Response rate of the cohort was 48%. Multivariate analysis showed short lasting unilateral neuralgiform headache attacks (OR 6.71; 95% CI 1.49-30.05; p = 0.013) and prior response to greater occipital nerve block (OR 4.22; 95% CI 1.35-13.21; p = 0.013) were associated with increased likelihood of response. Presence of occipital pain (OR 0.27; 95% CI 0.09-0.76; p = 0.014) and the presence of severe anxiety and/or depression (as measured on hospital anxiety and depression score) at time of implantation (OR 0.32; 95% CI 0.11-0.91; p = 0.032) were associated with reduced likelihood of response. Conclusion Possible clinical predictors of response to occipital nerve stimulation for refractory chronic headaches have been identified. Our data shows that those with short-lasting unilateral neuralgiform headache attacks respond better than those with chronic migraine, and that a prior response to greater occipital nerve block is associated with positive outcomes. This study suggests that the presence of occipital pain and severe mood disorder at time of implant are both associated with poor outcomes to occipital nerve stimulation.

Long-term follow up of intractable chronic short lasting unilateral neuralgiform headache disorders treated with occipital nerve stimulation.

Background Occipital nerve stimulation is a potential treatment option for medically intractable short-lasting unilateral neuralgiform headache attacks. We present long-term outcomes in 31 patients with short-lasting unilateral neuralgiform headache attacks treated with occipital nerve stimulation in an uncontrolled open-label prospective study. Methods Thirty-one patients with intractable short-lasting unilateral neuralgiform headache attacks were treated with bilateral occipital nerve stimulation from 2007 to 2015. Data on attack characteristics, quality of life, disability and adverse events were collected. Primary endpoint was change in mean daily attack frequency at final follow-up. Results At a mean follow-up of 44.9 months (range 13-89) there was a 69% improvement in attack frequency with a response rate (defined as at least a 50% improvement in daily attack frequency) of 77%. Attack severity reduced by 4.7 points on the verbal rating scale and attack duration by a mean of 64%. Improvements were seen in headache-related disability and depression. Adverse event rates were favorable, with no electrode migration or erosion reported. Conclusion Occipital nerve stimulation appears to offer a safe and efficacious treatment for refractory short-lasting unilateral neuralgiform headache attacks with significant improvements sustained in the long term. The procedure has a low adverse event rate when conducted in highly specialised units.

Pulsatile versus non-pulsatile tinnitus in idiopathic intracranial hypertension.

INTRODUCTION: Tinnitus is a symptom commonly associated with idiopathic intracranial hypertension (IIH) that can have a profound effect on quality of life. We aim to determine tinnitus symptom response after dural venous sinus stenting (DVSS) or CSF diversion with a shunt, in patients with both pulsatile (PT) and non-pulsatile tinnitus (NPT). METHODS: Single-centre cohort of IIH patients (2006-2016) who underwent 24-h ICP monitoring (ICPM). An un-paired t test compared ICP and pulse amplitude (PA) values in IIH patients with PT vs. NPT. RESULTS: We identified 59 patients with IIH (56 F:3 M), mean age 32.5 ± 9.49 years, 14 of whom suffered from tinnitus. Of these 14, seven reported PT and seven reported NPT. Patients with tinnitus had a mean 24-h ICP and PA of 9.09 ± 5.25 mmHg and 6.05 ± 1.07 mmHg respectively. All 7 patients with PT showed symptom improvement or resolution after DVSS (n = 4), secondary DVSS (n = 2) or shunting (n = 1). In contrast, of the 7 with NPT, only 1 improved post intervention (DVSS), despite 2 patients having shunts and 5 having DVSS. CONCLUSIONS: NPT and PT were equally as common in our group of IIH patients. DVSS appears to be an effective management option for IIH patients with a clear history of pulsatile tinnitus. However, non-pulsatile tinnitus was more persistent and did not respond well to either DVSS or CSF diversion.

Occipital Nerve Stimulation for Medically Refractory Chronic Paroxysmal Hemicrania.

OBJECTIVE: To describe the outcome of a patient with refractory chronic paroxysmal hemicrania (CPH) to occipital nerve stimulation (ONS). BACKGROUND: CPH is a primary headache disorder exquisitely sensitive to indomethacin. In patients unable to tolerate indomethacin, the therapeutic options are limited. ONS is a promising therapy for other refractory headache conditions. We report the first patient with medically refractory CPH treated with ONS. METHODS: Following implantation of the occipital nerve stimulator in 2006, the patient kept prospective headache diaries. Outcome was assessed by daily attack frequency. RESULTS: After a follow-up of over 10 years, the patient reported a sustained efficacy of more than 50% reduction in attack frequency and was pain-free at final follow-up. The patient was able to stop indomethacin completely. The patient had three successful pregnancies during follow-up. One system revision was undertaken alongside an expected battery replacement to treat unequal paresthesia and pain over the electrodes. CONCLUSION: ONS may offer an effective long-term treatment for CPH in patients where indomethacin cannot be tolerated.

Effect of venous stenting on intracranial pressure in idiopathic intracranial hypertension.

BACKGROUND: Idiopathic intracranial hypertension (IIH) is characterised by an increased intracranial pressure (ICP) in the absence of any central nervous system disease or structural abnormality and by normal CSF composition. Management becomes complicated once surgical intervention is required. Venous sinus stenosis has been suggested as a possible aetiology for IIH. Venous sinus stenting has emerged as a possible interventional option. Evidence for venous sinus stenting is based on elimination of the venous pressure gradient and clinical response. There have been no studies demonstrating the immediate effect of venous stenting on ICP. METHODS: Patients with a potential or already known diagnosis of IIH were investigated according to departmental protocol. ICP monitoring was performed for 24 h. When high pressures were confirmed, CT venogram and catheter venography were performed to look for venous stenosis to demonstrate a pressure gradient. If positive, venous stenting would be performed and ICP monitoring would continue for a further 24 h after deployment of the venous stent. RESULTS: Ten patients underwent venous sinus stenting with concomitant ICP monitoring. Nine out of ten patients displayed an immediate reduction in their ICP that was maintained at 24 h. The average reduction in mean ICP and pulsatility was significant (p = 0.003). Six out of ten patients reported a symptomatic improvement within the first 2 weeks. CONCLUSIONS: Venous sinus stenting results in an immediate reduction in ICP. This physiological response to venous stenting has not previously been reported. Venous stenting could offer an alternative treatment option in correctly selected patients with IIH.

Intraparenchymal intracranial pressure monitoring for hydrocephalus and cerebrospinal fluid disorders.

BACKGROUND: Elective intraparenchymal intracranial pressure (ICP) monitoring is useful for the diagnosis and treatment of hydrocephalus and cerebrospinal fluid (CSF) disorders. This retrospective study analyzes median ICP and pulse amplitude (PA) recordings in neurosurgically naïve patients undergoing elective ICP monitoring for suspected CSF disorders. METHODS: Retrospective review of prospectively collated database of neurosurgically naïve patients undergoing elective ICP monitoring for suspected hydrocephalus and CSF disorders. Following extraction of the median ICP and PA values (separated into all, day and night time recordings), principal component analysis (PCA) was performed to identify the principal factors determining the spread of the data. Exploratory comparisons and correlations of ICP and PA values were explored, including by post hoc diagnostic groupings and age. RESULTS: A total of 198 patients were identified in six distinct diagnostic groups (n = 21-47 in each). The PCA suggested that there were two main factors accounting for the spread in the data, with 61.4% of the variance determined largely by the PA and 33.0% by the ICP recordings. Exploratory comparisons of PA and ICP between the diagnostic groups showed significant differences between the groups. Specifically, significant differences were observed in PA between a group managed conservatively and the Chiari/syrinx, IIH, and NPH/LOVA groups and in the ICP between the conservatively managed group and high-pressure, IIH, and low-pressure groups. Correlations between ICP and PA revealed some interesting trends in the different diagnostic groups and correlations between ICP, PA, and age revealed a decreasing ICP and increasing PA with age. CONCLUSIONS: This study provides insights into hydrodynamic disturbances in different diagnostic groups of patients with CSF hydrodynamic disorders. It highlights the utility of analyzing both median PA and ICP recordings, stratified into day and night time recordings.

The predictive value of T-tau and AB1-42 levels in idiopathic normal pressure hydrocephalus.

BACKGROUND: Idiopathic normal pressure hydrocephalus (INPH) has no reliable biomarker to assist in the selection of patients who could benefit from ventriculo-peritoneal (VP) shunt insertion. The neurodegenerative markers T-tau and Aß1-42 have been found to successfully differentiate between Alzheimer's disease (AD) and INPH and therefore are candidate biomarkers for prognosis and shunt response in INPH. The aim of this study was to test the predictive value of cerebrospinal fluid (CSF) T-tau and Aß1-42 for shunt responsiveness. In particular, we pay attention to the subset of INPH patients with raised T-tau, who are often expected to be poor surgical candidates. METHODS: Single-centre retrospective analysis of probable INPH patients with CSF samples collected from 2006 to 2016. INDEX TEST: CSF levels of T-tau and Aß1-42. Reference standard: postoperative outcome. ROC analysis assessed the predictive value. RESULTS: A total of 144 CSF samples from INPH patients were analysed. Lumbar T-tau was a good predictor of post-operative mobility (AUROC 0.80). The majority of patients with a co-existing neurodegenerative disease responded well, including those with high T-tau levels. CONCLUSION: INPH patients tended to exhibit low levels of CSF T-tau, and this can be a good predictor outcome. However levels are highly variable between individuals. Raised T-tau and being shunt-responsive are not mutually exclusive, and such patients ought not necessarily be excluded from having a VP shunt. A combined panel of markers may be a more specific method for aiding selection of patients for VP shunt insertion. This is the most comprehensive presentation of CSF samples from INPH patients to date, thus providing further reference values to the current literature.