Lower Intracranial Pressure Research Articles

Intracranial pressure monitoring in patients with spontaneous onset of orthostatic headache.

Spontaneous intracranial hypotension (SIH) is a debilitating disorder, with an estimated annual incidence of 3.7 per 100,000. Diagnosing SIH can be challenging for clinicians, as patients frequently present with normal investigation findings. Intracranial pressure (ICP) monitoring has been proposed as a valuable tool for patients with orthostatic headaches that are highly suggestive of SIH but have inconclusive investigation results. The primary objective of this study was to determine the proportion of patients with spontaneous orthostatic headaches and normal diagnostic work-up who exhibited abnormal ICP monitoring results. This single-centre, retrospective observational study was conducted at a tertiary referral centre specialising in SIH and CSF dynamics disorders. Consecutive patients with spontaneous orthostatic headaches and inconclusive diagnostic work-up who underwent 24-hour ICP monitoring were considered eligible. The 24-hour ICP monitoring followed a standardised protocol, measuring median ICP and pulse amplitude (a marker of brain compliance) during the daytime, nighttime, and over the entire 24-hour period. Specific cut-offs for low and high ICP states were predetermined based on the best available current evidence. Thirty-eight patients (23 females, mean age 41 years ± 14SD) were identified. All patients had orthostatic headaches with a spontaneous onset. The mean duration of symptoms was 46 months ± 36SD. ICP monitoring identified 3 patients (7.9%) with low ICP (mean of the median 24-hour ICP - 2 mmHg ± 2SD) and 6 patients (15.8%) with high ICP (mean of the median 24-hour ICP 9 mmHg ± 3SD). Obvious CSF dynamics disturbances were excluded in the remaining 29 patients (76.3%, mean of the median 24-hour ICP 3 mmHg ± 3SD). The only clinical feature that was more common in patients with abnormal ICP compared to patients with normal ICP results was audiovestibular disturbance, namely aural fullness or muffled hearing (67% versus 17%, p = 0.015). There were no complications from the ICP monitoring procedure for any patient. When appropriately selected, patients with a clinical picture highly suggestive of SIH, who have a negative diagnostic work-up, may benefit from consideration of invasive ICP monitoring. Moreover, a significant minority of patients with orthostatic headache may paradoxically have a high CSF pressure state, which can be detected using ICP monitoring. Portions of this work were presented in abstract and oral presentation form at the Twenty-eighth Anglo-Dutch Migraine Association meeting (08/06/2018), the Tenth Meeting of the International Society for Hydrocephalus and Cerebrospinal Fluid Disorders (20/10/2018; Bologna, Italy), the Society of British Neurological Surgeons 2018 Autumn Meeting (19/09/2018; London, United Kingdom), and the European Association of Neurosurgical Societies 2023 congress (27/09/2023; Barcelona, Spain). This work is also part of the doctoral thesis of one of the authors (LD).

A randomized sequential cross-over trial evaluating five purportedly ICP-lowering drugs in idiopathic intracranial hypertension.

To gain initial insight into the efficacy to lower intracranial pressure (ICP), side effects, and effects on cognition of five drugs commonly used to treat idiopathic intracranial hypertension (IIH). Limited clinical data exist for the treatment for IIH. Impaired cognition is recognized in IIH and can be exacerbated by medications. This human experimental medicine study was a secondary analysis that focused on an unblinded randomized, sequential, cross-over extension of a previously completed randomized controlled trial. This study evaluated females with active IIH, recruited from University Hospital Birmingham, UK. Participants were treated, in randomized order, for 2 weeks with acetazolamide, amiloride, furosemide, spironolactone, and topiramate; assessment was at baseline and 2 weeks with a minimum 1-week drug washout between drugs. The primary outcome was change in ICP at 2 weeks post-drug administration. The cognitive evaluation was an exploratory study of the trial. ICP was recorded with telemetric, intraparenchymal ICP monitors (Raumedic, Hembrechts, Germany). Adverse events were recorded, and cognition was assessed utilizing the National Institutes of Health Toolbox Cognitive Battery. Fourteen participants were recruited and evaluated by intention-to-treat analysis. Mean (standard deviation) body mass index was 37.3 (7.0) kg/m2 and ICP was 33.2 (7.1) cm cerebrospinal fluid (CSF) at baseline. ICP fell with four drugs (mean [standard error (SE)]), acetazolamide -3.3 (1.0) mmHg, p = 0.001, furosemide -3.0 (0.9) mmHg, p = 0.001, spironolactone -2.7 (0.9) mmHg, p = 0.003, and topiramate -2.3 (0.9) mmHg, p = 0.010. There was no significant difference between drugs. Side effects were common with acetazolamide (100%, 11/11) and topiramate (93%, 13/14). Baseline cognitive performance was impaired, T-score (mean [SE]) 37.2 (2.6). After treatment, there was a further significant reduction in the fluid cognition domain (ability to process and integrate) with acetazolamide (mean T-score [SE]), -5.0 (2.6), p = 0.057 and topiramate -4.1 (2.0), p = 0.061. Acetazolamide, furosemide, spironolactone, and topiramate marginally reduced ICP. While their effects were not significant, this study was not powered to detect a difference between drugs. Participants reported significant side effects with acetazolamide and topiramate including cognitive decline. Cognitive measures were impaired by acetazolamide and topiramate. Therapeutics with greater efficacy and a favorable side effect profile are an unmet need in the treatment of IIH.

A prospective observational study on intracranial pressure management: A comparison of three ultrasound techniques.

This prospective observational study aimed to assess the effectiveness of B-mode ultrasound, color-coded Doppler, and shear-wave elastography in predicting intracranial pressure (ICP) and their capability to evaluate the efficacy of ICP lowering therapy. Forty-eight neuro-critical care patients were enrolled and categorized into 2 groups based on ICP measurements obtained through external ventricular drainage: the intracranial hypertension (IH) and normal ICP groups. The optic nerve (ON) sheath diameter (ONSD), end diastolic velocity, peak systolic velocity, resistance index of the central retinal artery (CRA), and Young's modulus (YM) of the ON were recorded after external ventricular drainage placement and following ICP lowering treatment in the IH group. The median values of ONSD (5.35mm [IQR 5.03, 5.80mm] vs. 4.38mm [IQR 4.25, 4.60mm]) and YM of the ON (23.69kPa [IQR 18.83, 30.90kPa] vs. 10.48kPa [IQR 9.84, 12.41kPa]) were remarkably higher in the IH group than in the normal ICP group (both P<0.001). However, no obvious differences were observed in end diastolic velocity, peak systolic velocity, or resistance index of the CRA between the two groups (all P>0.05). Additionally, analysis of the differences in ultrasound parameters before and after treatment revealed that ΔYM of the ON exhibited higher sensitivity and specificity in detecting successful treatment of IH compared to ΔONSD. ΔYM of the ON may serve as a more valuable parameter for reflecting changes in ICP and predicting the efficacy of treatment. In contrast, the color-coded Doppler indices of the CRA had limited values in evaluating ICP.

Venous compression causes chronic cerebral ischaemia in normal pressure hydrocephalus patients

BackgroundCerebral autoregulation is a robust regulatory mechanism that stabilizes cerebral blood flow in response to reduced blood pressure, thereby preventing cerebral ischaemia. Scientists have long believed that cerebral autoregulation also stabilizes cerebral blood flow against increases in intracranial pressure, which is another component that determines cerebral perfusion pressure. However, this idea was inconsistent with the complex pathogenesis of normal pressure hydrocephalus, which includes components of chronic cerebral ischaemia due to mild increases in intracranial pressure.MethodsTwenty-one patients who underwent ventriculoperitoneal shunt surgery for normal pressure hydrocephalus were included in this study. To determine the pressure setting of the Codman-Hakim programmable valve, intracranial pressure was measured after shunt surgery by puncturing the Ommaya reservoir, which formed a closed circuit with the needle and the syringe. Then, intracranial pressure was continuously measured with intermittent infusion of cerebrospinal fluid from the same closed circuit. We also continuously measured oximetry data, such as regional cerebral oxygen saturation derived from near-infrared spectroscopy monitoring. These data were digitized, recorded, and used for calculating intracranial compliance and the relationship between cerebrospinal fluid volume loading and intracranial pressure.ResultsThis study demonstrates that in patients with normal pressure hydrocephalus, cerebral venous vascular bed compression induces mild cerebral ischaemia when intracranial pressure is slightly higher than physiological venous pressure. Cerebral venous compression impairs cerebral blood flow by quadratically increasing circulatory resistance according to Poiseuille’s law. Furthermore, chronic cerebral ischaemia occurred even at low or normal intracranial pressures when deep and subcortical white matter hyperintensities (DSWMHs) were severe.ConclusionThe fact that cerebral blood flow impairment begins at very low intracranial pressures indicates that cerebral autoregulation to compensate for reduced venous blood flow is not functioning adequately in NPH. These processes provide a link between impaired cerebrospinal fluid circulation, cerebral autoregulation, and neurological dysfunction, which has been missing in patients with NPH involving small vessel arteriosclerosis. These findings may provide insight into similar conditions, such as normal-tension glaucoma and chronic kidney disease, in which a mild increase in local compartment pressure leads to chronic ischemia in organs protected by autoregulatory mechanisms.

Dura fenestration is non-inferior and with lower complication incidence compared to augmented duraplasty in decompressive craniectomy.

Decompressive craniectomy is a procedure for managing elevated intracranial pressure (ICP). However, it carries a high morbidity and mortality toll. While there is relative consensus regarding the bony part of the decompression, the role of dura opening and the optimal technique to perform it are under debate. Here we compared the commonly used augmented duraplasty technique to an understudied technique of dura fenestrations in a single center, prospective, non-controlled randomized study. The study included 23 patients who underwent decompressive craniectomy. The lowering of ICP was significant in both methods when compared to preoperative values and compared to pre-duraplasty values. The ICP was similar in various postoperative time points between both techniques. The rate of complications was lower when the dura was fenestrated - brain herniation was over five time less common, infection was more than five times rarer. Contusion expansion, meningitis and contralateral subdural collection were all lower in fenestrated dura cases than in wide dura opening. These results hold promise for a superior surgical approach in duraplasty for intracranial pressure reduction.

Safety of flow-controlled ventilation with positive and negative end-expiratory pressure in a swine model of intracranial hypertension

BackgroundPatients with brain damage often require mechanical ventilation. Although lung-protective ventilation is recommended, the application of increased positive end-expiratory pressure (PEEP) has been associated with elevated intracranial pressure (ICP) due to altered cerebral venous return. This study investigates the effects of flow-controlled ventilation (FCV) using negative end-expiratory pressures (NEEP), on cerebral hemodynamics in a swine model of intracranial hypertension.MethodsA model of intracranial hypertension involving bilateral trepan bolt holes was performed in 14 pigs. Pressure-controlled volume-guaranteed ventilation (PCV-VG) with PEEP and FCV using PEEP and then NEEP were applied. Intracranial pressure and oxygenation, as well as systemic hemodynamics and gas exchange parameters, were continuously monitored. Data were collected at baseline and at varying PEEP levels for both PCV-VG and FCV ventilation modalities. Following this, FCV ventilation and NEEP levels of -3, -6 and -9 cmH2O were applied.ResultsICP remained stable with low PEEP levels, but significantly decreased with NEEP. Lower ICP following NEEP improved cerebral perfusion pressure and cerebral tissue oxygenation (p < 0.05 for all). FCV with NEEP at EEP-6 and EEP-9 significantly improved cardiac output and mean arterial pressure (MAP), compared to PCV-VG and FCV using PEEP (p < 0.05, respectively). There were no significant differences in gas exchange parameters between modalities (PCV-VG vs FCV), and between the application of PEEP or NEEP. No significant correlations were observed between ΔICP and ΔMAP.ConclusionThe application of FCV with NEEP appears to be a safe ventilation mode and offers an additional tool for controlling severe intracranial pressure episodes. These findings warrant validation in future studies and may lead to important potential applications in clinical practice.

New onset of ataxic dysarthria with CSF overdrainage syndrome: A case report

Cerebrospinal fluid (CSF) overdrainage syndrome occurs when excessive CSF drainage from the cranial cavity results from a spinal CSF leak or overdrainage through a ventriculoperitoneal (VP) or lumboperitoneal (LP) shunt. Symptoms include severe orthostatic headache, worsening with sitting or standing but improving when recumbent. The headache is typically dull, throbbing, and bilateral and may be exacerbated by Valsalva maneuver, coughing, or straining. Additional symptoms can include dizziness, nausea, vomiting, gait disturbances, diplopia, back pain, and seizures. We present a case of overdrainage syndrome following LP shunt placement for idiopathic intracranial hypertension in a 38-year-old woman with Ehlers&amp;ndash;Danlos syndrome (EDS). One year post-surgery, she reported worsening headaches and nausea after prolonged upright positioning. Neurological examination revealed cerebellar dysfunction, including dysdiadochokinesia, intention tremor, and ataxic dysarthria. This condition gradually emerged 6 months post-LP shunt placement and was attributed to chronic overdrainage. After 1 day of observation, the patient underwent surgery to clamp the LP shunt outflow, resulting in overnight symptom resolution, including ataxic speech. This case underscores the importance of recognizing ataxic dysarthria in conjunction with low intracranial pressure syndromes, particularly in patients with EDS. It emphasizes the need to be aware of the diverse clinical manifestations of EDS and their relationship to altered CSF pressure syndromes.

A comprehensive study of risk factors predicting hydrocephalus following decompressive craniectomy in traumatic brain injuries

IntroductionDecompressive craniectomy [DC] is one of the leading armaments to lower refractory intracranial pressure. Post-DC hydrocephalus [PDCH] occurs in 11.9–36% of patients undergoing DCs for TBIs. Various theories have been given regarding pathophysiological mechanism of PDCH but remain dubious. Risk factors predicting PDCH still under research. Exact timeline regarding developmental process of PDCH remains undefined.MethodThis retrospective study was conducted on 422 patients who underwent DCs in our tertiary care trauma center over the period of one year. 60 patients out of 422 who developed PDCH were analyzed with respect to demographic variables and preoperative and postoperative risk factors. A total of 20 randomly selected patients, who underwent DCs but did not develop hydrocephalus, were selected and compared with patients who developed PDCH. Outcome analysis was done by dichotomizing the groups into independent and dependent groups.ResultsAmong 422 patients undergoing DC, 14.21%[n = 60] developed PDCH. Younger [34.2 y vs 43.3 y, p = 0.0004] male age group was predominant in our study. Age [p = 0.021, multivariate analysis] and midline shift [p = 0.008, multivariate analysis] were significant preoperative predicting risk factors for PDCH. Interhemispheric hygroma [p = 0.031], brain bulge [ p = 0.008], and blood in postoperative scan [p = 0.029] were significant postoperative risk factors. Lower GCS score at admission [p = 0.0003], postoperative day 10 and at the time of establishment of PDCH were significantly predicted surgery to hydrocephalus time. Midline shift [p = 0.007] and thickness of interhemispheric hygroma [p = 0.021] were associated with poor outcome in patients with PDCH.ConclusionYounger age group and presence of midline shift are significant preoperative predictors of PDCH. Blood in postoperative scan, interhemispheric hygroma and brain bulge in postoperative period are significant predictors for PDCH. Deterioration in GCS score in postoperative period following DC should be taken as high index of suspicion for developing PDCH.

Cerebrospinal fluid venous fistula causing spontaneous intracranial hypotension resulting in venous sinus thrombosis and coma.

Cerebrospinal fluid (CSF) fistulas have recently been recognized as a cause of spontaneous intracranial hypotension (SIH), predominantly presenting with headaches, especially positional headaches. Atypical presentations like tinnitus and cranial nerve symptoms have also been reported. SIH has been linked to venous sinus thrombosis; however, to our knowledge, no prior cases describe a CSF venous fistula causing SIH that leads to cerebral venous thrombosis and coma. We report a patient who developed progressive venous sinus thrombosis, leading to coma, and was found to have low intracranial pressure indicative of SIH. Invasive monitoring and imaging confirmed the low intracranial pressure, prompting a dynamic myelogram that revealed a T2/3 CSF venous fistula. The patient underwent transvenous embolization of the fistula, which resulted in the resolution of symptoms and almost immediate improvement in both venous thrombosis and intracranial hypotension. CSF venous fistulae as a cause of SIH is a recently recognized entity, with ongoing research into its treatment through transvenous embolization. Most documented cases focus on patients with headaches. This case highlights a novel presentation, emphasizing the importance of thorough diagnostic workup in patients with cerebral venous thrombosis. Early detection and treatment of this condition can lead to significant clinical improvement, including the resolution of coma.

Effects of moderate sedation induced by propofol or midazolam on intracranial pressure

Introduction: Propofol and midazolam are the main options for moderate sedation in clinical practice. In addition, these drugs are used to reduce intracranial pressure in cases of intracranial hypertension, and their use in these situations is guided by limited evidence. Objective: To compare the effects of propofol and midazolam on intracranial pressure wave morphology in moderate sedation in patients undergoing upper digestive endoscopy. Methods: Sixty patients were included in this study, being divided into two groups, propofol and midazolam group. Intracranial pressure was monitored during and after upper digestive endoscopy, using non-invasive monitoring equipment developed by the company Brain4care. Arterial pressure was measured before and after the exam. Results: The propofol group had lower intracranial pressure (p=0.037) during moderate sedation compared to intracranial pressure after endoscopy and a significant decrease in systolic (p=0.0001) and diastolic pressure (p=0.001) after sedation. Midazolam, on the other hand, reduced systolic pressure (p=0.001), but didn’t change the other parameters after the procedure. There wasn’t a significant difference between the propofol and midazolam groups. Conclusion: There was no significant difference between the groups studied, however, analyses within the propofol and midazolam groups indicate that propofol, but not midazolam, causes changes in intracranial pressure in moderate sedation.

Orthostatic Hemifacial Spasm in Idiopathic Intracranial Hypertension.

Among the symptoms seen in idiopathic intracranial hypertension (IIH), hemifacial spasm (HFS) is rare. Orthostatic-induced HFS preceding lumbar puncture (LP) is previously unreported. We treated two patients with unusual IIH presentations. This case series reviews the few reports of HFS in IIH and proposes a mechanism for spasm occurrence. Case 1: A woman in her mid-40s with previously controlled IIH developed daily headache, pulsatile tinnitus, right-sided trigeminal paresthesia, and right-sided HFS. The latter 2 symptoms occurred exclusively when moving from a sitting to a standing position. Imaging was unremarkable; opening pressure (OP) on LP was 46 cmH2O with normal cerebrospinal fluid (CSF) components. Case 2: A woman in her late 40s presented with severe daily headache, pulsatile tinnitus, and left-sided HFS following weight gain. Imaging was unremarkable; OP on LP was 32 cmH2O with normal CSF components. HFS episodes persisted following LP in both patients. Increasing and initiating acetazolamide, respectively, resolved all symptoms. Earlier suggested mechanisms of HFS are based on elevated intracranial pressure (ICP) shifting the facial nerve into proximity of a vascular structure. HFS appearing upon standing and continuing after LP, and thus a lower ICP, contradicts this. We propose a mechanism based on the degree of ICP change. This theory is grounded in the lack of intracranial compliance in IIH, wherein substantial pressure changes occur following small volume changes.

Biomechanical instability of the brain-CSF interface in hydrocephalus.

Hydrocephalus, characterized by progressive expansion of the CSF-filled ventricles (ventriculomegaly), is the most common reason for brain surgery. 'Communicating' (i.e. non-obstructive) hydrocephalus is classically attributed to a primary derangement in CSF homeostasis, such as choroid plexus-dependent CSF hypersecretion, impaired cilia-mediated CSF flow currents, or decreased CSF reabsorption via the arachnoid granulations or other pathways. Emerging data suggest that abnormal biomechanical properties of the brain parenchyma are an under-appreciated driver of ventriculomegaly in multiple forms of communicating hydrocephalus across the lifespan. We discuss recent evidence from human and animal studies that suggests impaired neurodevelopment in congenital hydrocephalus, neurodegeneration in elderly normal pressure hydrocephalus and, in all age groups, inflammation-related neural injury in post-infectious and post-haemorrhagic hydrocephalus, can result in loss of stiffness and viscoelasticity of the brain parenchyma. Abnormal brain biomechanics create barrier alterations at the brain-CSF interface that pathologically facilitates secondary enlargement of the ventricles, even at normal or low intracranial pressures. This 'brain-centric' paradigm has implications for the diagnosis, treatment and study of hydrocephalus from womb to tomb.

Atypical psychosis in a patient with intracranial hypertension: clinical case and review

IntroductionSeveral neurologic conditions can produce or mimic psychotic symptoms. It is important to make an exhaustive differential diagnosis between a psychiatric manifestation of an underlying neurological condition and a primary psychiatric one. We explore through the present clinical case of a young woman admitted to neurology the relationship between intracranial hypertension and a case of atypical psychosis that resolved itself with the treatment of the intracranial hypertension, without the need for antipsychotic medication.ObjectivesTo explore through the presented clinical case and the concerning literature the concept and management of psychotic-like symptoms in patients with intracranial hypertension.MethodsWe present a clinical case and a review of the existing literature concerning atypical psychosis or psychosis-like symptoms in cases of intracranial hypertension.ResultsWe report the case of a 24 year old woman with no relevant medical history hospitalised in the neurology unit due to suspected encephalitis. Native to New Zealand, she is brought from the airport due to behavioural alterations. During the last few days before admission she had presented with incoherent speech, derailment, religious and persecutory delusions, and erotomania towards her cousin. She described feelings of strangeness with her surroundings and of time moving at a different speed than usual, either faster or slower. She also had a headache and visual alterations, as well as memory errors concerning recent events, clouding of consciousness and inattention.No fever or other relevant physical symptoms. A lumbar puncture is done, which shows an opening pressure of 37mmHg but no other anomalies. Body CT scan shows no relevant findings. Empirical treatment with dexamethasone is initiated for suspected encephalitis, progressively reducing the dosage until suspension in the following days. During her stay at the hospital she is assessed by ophthalmology, which finds no abnormalities in the eye fundus examination, and psychiatry. A second evacuating lumbar punture is done to reduce intracraneal hypertension. No antipsychotic treatment is initiated: the symptomatology remitted with the lowering of intracranial pressure. At time of discharge, the patient remained asymptomatic without treatment and was able to return home to continue outpatient neurologic study of the etiology of the intracranial hypertension.Finally, we conduct a review ot the existing literature concerning psychotic and psychosis-like symptoms in patients with intracranial hypertension, to explore the diagnostic and management options of this rare finding.ConclusionsOur findings point to the existing relationship between intracranial hypertension and psychosis-like symptoms. Further studies on pathogenic mechanisms and therapeutic management are required.Disclosure of InterestNone Declared

Critical ICP thresholds in relation to outcome: Is 22 mmHg really the answer?

PurposeIntensive care for patients with traumatic brain injury (TBI) aims, among other tasks, at avoiding high intracranial pressure (ICP), which is perceived to worsen motor and cognitive deficits and increase mortality. International recommendations for threshold values for ICP were increased from 20 to 22 mmHg in 2016 following the findings in a study by Sorrentino et al., which were based on an observational study of patients with TBI of averaged ICP values. We aimed to reproduce their approach and validate the findings in a separate cohort.MethodsThree hundred thirty-one patients with TBI were included and categorised according to survival/death and favourable/unfavourable outcome at 6 months (based on Glasgow Outcome Score—Extended of 6–8 and 1—5, respectively). Repeated chi-square tests of survival and death (or favourable and unfavourable outcome) vs. high and low ICP were conducted with discrimination between high and low ICP sets at increasing values (integers) between 10 and 35 mmHg, using the average ICP for the entire monitoring period. The ICP limit returning the highest chi-square score was assumed to be the threshold with best discriminative ability. This approach was repeated after stratification by sex, age, and initial Glasgow Coma Score (GCS).ResultsAn ICP limit of 18 mmHg was found for both mortality and unfavourable outcome for the entire cohort. The female and the low GCS subgroups both had threshold values of 18 mmHg; for all other subgroups, the threshold varied between 16 and 30 mmHg. According to a multiple logistic regression analysis, age, initial GCS, and average ICP are independently associated with mortality and outcome.ConclusionsUsing identical methods and closely comparable cohorts, the critical thresholds for ICP found in the study by Sorrentino et al. could not be reproduced.

Spontaneous Intracranial Hypotension: Long-Term Follow-Up

The outcome of spontaneous intracranial hypotension (SIH) years after onset is largely unknown. The objective of our study was to describe our clinical experience and long-term outcomes in a case series of patients with SIH. From March 2007 to March 2022, demographic variables, clinical symptoms, neuroimaging findings, and response to treatment were retrospectively analyzed in patients with confirmed SIH and in a subgroup of patients with clinical symptoms but not confirmed by MR or LP, probable SIH (pSIH). We have included 37 SIH and 13 pSIH patients. The average age at onset was 44 years, and 59% (pSIH 46%) were women. All patients presented with a new-onset orthostatic headache. In the SIH group, brain MRI showed signs of intracranial hypotension in all patients, spinal MR was performed in 70%, and pathological findings were identified in 73%. The range of EBP was 1-8 (average 2.2). Good outcome after single or 2 EBPs had 42% (pSIH 46%) of patients. At follow-up, 81% (pSIH 54%) of patients had a favorable outcome. Relapse occurred in 16% of patients in the SIH group and none in the pSIH group. The mean follow-up time was 60 months. EBP is an effective and minimally invasive treatment, and efficacy seems independent of disease duration. The long-term prognosis is favorable in 80% of SIH patients and in half of pSIH patients. Despite the lack of MRI signs of low intracranial pressure on neuroimaging, pSIH patients should also be offered EBP, and more awareness of SIH is needed.

“Dual‐pressure theory” in pathogenesis of glaucomatous optic neuropathy from the Beijing intracranial and intraocular pressure study

AbstractThe mechanical theory of glaucoma indicates that high intraocular pressure (IOP) leads to glaucomatous optic nerve damage. However, nearly half of primary open‐angle glaucoma patients with normal intraocular pressure also exhibit progression of what appears to be glaucomatous optic nerve damage. Our earlier prospective study identified for the first time that the relatively low intracranial pressure (ICP) is also an important risk factor for progressive glaucomatous injury of normal‐tension glaucoma. When considering the results of studies in nonhuman primates, clinical research, large‐scale natural‐population studies, and basic laboratory investigations, a new understanding of the pathophysiology of glaucoma, the “Dual‐Pressure Theory”, has been proposed. This theory states that “either high IOP or low ICP contributes to increasing the translaminar cribrosa pressure difference; it is the pressure difference rather than the IOP alone that results in the glaucomatous optic neuropathy”. Here, we provide a systematic introduction to Dual‐Pressure Theory relating to glaucoma, the form of a research map, an outline of basic laboratory investigations, the main methodology, and research updates.

The Third Hand of Neurosurgeons - a novel intraoperative malleable adjustable continuous suction tube.

We designed a novel intraoperative malleable adjustable continuous suction tube to obtain clear surgical fields, reduce intracranial pressure, and lower the temperature of the surgical area. This device consists of six parts: continuous suction tube head and cotton patty, suction tube, fixed wire position, fixed clip, spiral plastic pressure regulating valve, and tail. It can continuously extract blood, cerebrospinal fluid, and rinsing solution from surgical fields, with minimal contact and trauma to tissues, nerves, and blood vessels, while also having a negligible impact on the surgeon's focus and procedure. The excellent and safe performance (simple, malleable, adjustable, space-saving, inexpensive, safe, and effective) of this device in clearing the operating field has been proven in more than 2000 neurosurgical operative procedures. We encountered no complications associated with this device, such as cerebral hematoma, postoperative low intracranial pressure, or vascular and nerve injuries. The newly innovated intraoperative malleable adjustable continuous suction tube is effective and safe for microneurosurgery.

Effect of glucagon like peptide-1 receptor agonist exenatide, used as an intracranial pressure lowering agent, on cognition in Idiopathic Intracranial Hypertension

BackgroundCognitive function can be affected in conditions with raised intracranial pressure (ICP) such as idiopathic intracranial hypertension (IIH). Drugs used off label to treat raised ICP also have cognitive side effects, underscoring the unmet need for effective therapeutics which reduce ICP without worsening cognition. The Glucagon Like Peptide-1 (GLP-1) receptor agonist, exenatide, has been shown to significantly reduce ICP in IIH, therefore this study aimed to determine the effects of exenatide on cognition in IIH.MethodsThis was an exploratory study of the IIH:Pressure trial (ISTCRN 12678718). Women with IIH and telemetric ICP monitors (n = 15) were treated with exenatide (n = 7) or placebo (n = 8) for 12 weeks. Cognitive function was tested using the National Institute of Health Toolbox Cognitive Battery at baseline and 12 weeks.ResultsCognitive performance was impaired in fluid intelligence ((T-score of 50 = population mean), mean (SD) 37.20 (9.87)), attention (33.93 (7.15)) and executive function (38.07 (14.61)). After 12-weeks there was no evidence that exenatide compromised cognition (no differences between exenatide and placebo). Cognition improved in exenatide treated patients in fluid intelligence (baseline 38.4 (8.2), 12 weeks 52.9 (6.6), p = 0.0005), processing speed (baseline 43.7 (9.4), 12 weeks 58.4 (10.4), p = 0.0058) and episodic memory (baseline 49.4 (5.3), 12 weeks 62.1 (13.2), p = 0.0315).ConclusionsIn patients with raised ICP due to IIH, exenatide, a drug emerging as an ICP lowering agent, does not adversely impact cognition. This is encouraging and has potential to be relevant when considering prescribing choices to lower ICP.

Propofol-based Anesthesia versus Volatile Anesthesia on Brain Relaxation in Neurosurgery: A Meta-analysis of Randomized Controlled Trials

Background: The main objectives of neuroanesthesia are maintaining the stability of cerebral blood flow, intracranial pressure (ICP), and hemodynamics. Both intravenous and volatile anesthetics are frequently used in neuroanesthesia, yet the superior agent is still an ongoing debate. This study aimed to compare propofol-based versus volatile anesthesia on brain relaxation in patients undergoing neurosurgery. Subjects and Methods: PubMed, Cochrane, EMBASE, and ProQuest were searched using suitable keywords. Randomized controlled trials comparing propofol-based and volatile anesthesia for neurosurgery were included. The primary outcome was the brain relaxation score. Secondary outcomes were cerebral hemodynamics, intraoperative hemodynamics, recovery profiles, and postoperative complications. A meta-analysis was done to analyze the outcomes. Results: Seventeen studies (2135 patients) were included. Propofol-based group had lower ICP values (mean difference [MD]: −5.13 mmHg; 95% confidence interval [CI]: −6.95 to − 3.32; P &lt; 0.00001); however, brain relaxation was similar within both groups. Intraoperative hemodynamics parameters were similar, aside from higher hypertension incidence in the propofol-based group. Remifentanil usage was higher with propofol-based anesthesia (MD: 1.08 μg; 95% CI: 0.72–1.44; P &lt; 0.00001). Recovery profiles and postoperative complications were similar, with the exception of lower postoperative nausea and vomiting (PONV) incidence with propofol-based anesthesia (odds ratio = 0.59; 95% CI: 0.43–0.79; P = 0.0005). Conclusions: Propofol-based and volatile anesthesia provides comparable adequate brain relaxation in patients undergoing neurosurgery, although ICP was lower with propofol-based anesthesia. Propofol-based anesthesia significantly promoted the incidence of hypertension and reduced PONV. Other adverse events with both regimens were comparable.

Intracranial pressure monitoring for severe traumatic brain injury: A retrospective study of 273 consecutive patients.

Intracranial pressure (ICP) monitoring is essential in severe traumatic brain injury (sTBI) cases; yet, the frequency of high ICP occurrences remains debated. This study presents a 9-year analysis of ICP monitoring using intraventricular catheters among sTBI patients. A retrospective review of 1760 sTBI patients (Glasgow Coma Score <9) admitted between January 2011 and December 2019 was conducted. Of these, 280 patients meeting monitoring criteria were included based on Brain Trauma Foundation (BTF) Guidelines. ICP was monitored using intraventricular catheters through right frontal burr holes. Initial ICP readings were recorded intraoperatively, followed by continuous monitoring. Patients with ICP >20 mmHg for 10-15 min during 72 h were categorized with high ICP. Data collected included demographics, computed tomography (CT) findings, intra- and post-operative ICP, and complications. Of 273 patients, 228 were male and 45 females, aged 18-80 (71.30% aged 18-45). Traffic accidents were the primary cause (90.48%). Fifty-two-point seventy-five percent experienced high ICP, correlating significantly with subdural hematoma (P < 0.001), intraventricular hemorrhage (P < 0.013), and compressed basal cisterns (P = 0.046) on initial CT. Twenty patients (7.3%) developed meningitis. Lower mortality rates and improved outcomes were observed in the low ICP group across discharge 3-and 6-month follow-ups. Adherence to BTF guidelines yielded a 52.75% high ICP rate. Significant correlations were found between high ICP and specific CT abnormalities. This study underscores the benefits of ICP monitoring in selected sTBI cases, suggesting a need to review criteria for initiating monitoring protocols.