Lumbar Cerebrospinal Fluid Pressure Research Articles

Cerebrospinal Fluid Pressure Dynamics as a Bedside Test in Traumatic Spinal Cord Injury to Assess Surgical Spinal Cord Decompression: Safety, Feasibility, and Proof-of-Concept

Background Sufficient and timely spinal cord decompression is a critical surgical objective for neurological recovery in spinal cord injury (SCI). Residual cord compression may be associated with disturbed cerebrospinal fluid pressure (CSFP) dynamics. Objectives This study aims to assess whether intrathecal CSFP dynamics in SCI following surgical decompression are feasible and safe, and to explore the diagnostic utility. Methods Prospective cohort study. Bedside lumbar CSFP dynamics and cervical MRI were obtained following surgical decompression in N = 9 with mostly cervical acute-subacute SCI and N = 2 patients with non-traumatic SCI. CSFP measurements included mean CSFP, cardiac-driven CSFP peak-to-valley amplitudes (CSFPp), Valsalva maneuver, and Queckenstedt’s test (firm pressure on jugular veins, QT). From QT, proxies for cerebrospinal fluid pulsatility curve were calculated (ie, relative pulse pressure coefficient; RPPC-Q). CSFP metrics were compared to spine-healthy patients. computer tomography (CT)-myelography was done in 3/8 simultaneous to CSFP measurements. Results Mean age was 45 ± 9 years (range 17-67; 3F), SCI was complete (AIS A, N = 5) or incomplete (AIS B-D, N = 6). No adverse events related to CSFP assessments. CSFP rise during QT was induced in all patients [range 9.6-26.6 mmHg]. However, CSFPp was reduced in 3/11 (0.1-0.3 mmHg), and in 3/11 RPPC-Q was abnormal (0.01-0.05). Valsalva response was reduced in 8/11 (2.6-23.4 mmHg). CSFP dynamics corresponded to CT-myelography. Conclusions Comprehensive bedside lumbar CSFP dynamics in SCI following decompression are safe, feasible, and can reveal distinct patterns of residual spinal cord compression. Longitudinal studies are required to define critical thresholds of impaired CSFP dynamics that may impact neurological recovery and requiring surgical revisions.

Resisted Inspiration: A New Technique to Aid in the Detection of CSF-Venous Fistulas.

We describe a technique termed "resisted inspiration" that could be used during myelography to decrease superior vena cava venous pressure and increase lumbar CSF pressure, potentially aiding in the detection of CSF-venous fistulas.

Cerebrospinal fluid micro-volume changes inside the spinal space affect intracranial pressure in different body positions of animals and phantom.

Interpersonal differences can be observed in the human cerebrospinal fluid pressure (CSFP) in the cranium in an upright body position, varying from positive to subatmospheric values. So far, these changes have been explained by the Monroe–Kellie doctrine according to which CSFP should increase or decrease if a change in at least one of the three intracranial volumes (brain, blood, and CSF) occurs. According to our hypothesis, changes in intracranial CSFP can occur without a change in the volume of intracranial fluids. To test this hypothesis, we alternately added and removed 100 or 200 μl of fluid from the spinal CSF space of four anesthetized cats and from a phantom which, by its dimensions and biophysical characteristics, imitates the cat cerebrospinal system, subsequently comparing CSFP changes in the cranium and spinal space in both horizontal and vertical positions. The phantom was made from a rigid “cranial” part with unchangeable volume, while the “spinal” part was made of elastic material whose modulus of elasticity was in the same order of magnitude as those of spinal dura. When a fluid volume (CSF or artificial CSF) was removed from the spinal space, both lumbar and cranial CSFP pressures decreased by 2.0–2.5 cm H2O for every extracted 100 μL. On the other hand, adding fluid volume to spinal space causes an increase in both lumbar and cranial CSFP pressures of 2.6–3.0 cm H2O for every added 100 μL. Results observed in cats and phantoms did not differ significantly. The presented results on cats and a phantom suggest that changes in the spinal CSF volume significantly affect the intracranial CSFP, but regardless of whether we added or removed the CSF volume, the hydrostatic pressure difference between the measuring sites (lateral ventricle and lumbar subarachnoid space) was always constant. These results suggest that intracranial CSFP can be increased or decreased without significant changes in the volume of intracranial fluids and that intracranial CSFP changes in accordance with the law of fluid mechanics.

The comparative effects of desflurane and isoflurane on intraoperative cerebral hemodynamics, cardiovascular changes, and post-operative recovery in patients undergoing craniotomy for supratentorial tumors

Background: Preserving hemodynamic stability, providing a slack brain, and enabling early recovery are the main criteria of neuroanesthesia. The most commonly used volatile anesthetic for neurosurgeries is isoflurane due to its favorable effects on cerebral blood flow and intracranial pressure. On the other hand, desflurane, having lower blood gas partition coefficient, favors rapid recovery from anesthesia. Aims and Objectives: This study was conducted for comparing the effects of desflurane and isoflurane on intraoperative cerebral and cardiovascular hemodynamics and post-operative recovery among patients with supratentorial neoplasms posted for craniotomy. Materials and Methods: A total of 52 patients aged 20–60, ASA I and II, scheduled for craniotomy under general anesthesia, were randomized into Group I (isoflurane) and Group D (desflurane). All patients received standardized anesthetic protocol and anesthesia was maintained either with isoflurane or desflurane (≤1 MAC). Lumbar cerebrospinal fluid pressure (LCSFP) and cerebral perfusion pressure (CPP) were monitored every 5 min till dura was opened and the degree of dural tension and brain swelling were assessed by neurosurgeons, blinded to the study, at the time of dural opening. Perioperative heart rate, mean arterial pressure, and post-operative recovery time were also noted. Results: No statistically significant changes were observed among two groups regarding change in LCSFP, CPP, dural tension, brain swelling, and cardiovascular changes. Post-operative recovery time was significantly shorter in desflurane group (P<0.001) than isoflurane group. Conclusion: Desflurane and isoflurane both can be used safely in maintaining neuroanesthesia. However, due to a significantly faster recovery which facilitates early post-operative neurological assessment, desflurane may be considered a better alternative to isoflurane.

Comparison of the Range of Lumbar Cerebrospinal Fluid Pressure in Adults With Normal Cerebrospinal Fluid Pressure and in Idiopathic Intracranial Hypertension.

Lumbar puncture CSF pressure measurements in a large group of adults (116) having lumbar puncture (LP) for diagnostic reasons with no clinical indication of raised intracranial pressure were used to establish the normal range of CSF pressure. The cerebrospinal fluid (CSF) pressure was also measured in a smaller unselected series of patients (35) with the syndrome of idiopathic intracranial hypertension (IIH). All the lumbar punctures were performed by the same highly skilled operator, a consultant nurse, to ensure accuracy of measurement. The results showed that the mean CSF pressure was 18.7 cm H 2 O with a range of 1-29 cm H 2 O in the group with normal CSF pressure. Ninty-five percentage of values was below 29 cm H 2 O in the group with normal CSF pressure. In the series with IIH, the mean and range were 37.7 cm H 2 O and 29.5-66 cm H 2 O, respectively. The lowest recorded pressure in the IIH group was 29.5 cm H 2 O with 95% of values above 31. This is the first time that the normal range of CSF pressure and that found in a group of patients with IIH has been reported after LP performed by the same operator to ensure inaccuracy of measurement has not biased the results. It suggests that the current upper limit of normal adopted by the revised diagnostic criteria for IIH (25 cm H 2 O) may be too low. The range of normal CSF pressure and that found in patients with IIH in our study suggests that consideration should be given to revising the upper limit of normal CSF pressure to around 30 cm H 2 O.

The association of cerebrospinal fluid pressure with optic nerve head and macular vessel density.

The present study aims to investigate the effect of temporary cerebrospinal fluid pressure (CSFP) reduction on optic nerve head (ONH) and macular vessel density (VD) using optical coherence tomography angiography. Forty-four eyes of 44 adults with diagnostic lumbar puncture and CSFP reduction were recruited. Thirty-two eyes of 32 healthy volunteers were controls. ONH and macular VD images were evaluated differences between baseline and after CSFP reduction. The results showed that the mean CSFP decreased from (11.6±2.1) mmHg to (8.2±3.4) mmHg (P<0.001). VD in the macular regions decreased significantly after CSFP reduction in the study group (all P<0.05). The control group showed no significant changes in macular VD (all P>0.05). In the study group, decreased VD in the macular parainferior region was associated with CSFP reduction (R2=0.192, P=0.003), the reduction of macular VD in parafoveal (R2=0.098, P=0.018), parainferior (R2=0.104, P=0.021), parasuperior (R2=0.059, P=0.058), paranasal (R2=0.057, P=0.042), paratemporal (R2=0.079, P=0.026) was associated with mean ocular perfusion pressure decrease following CSFP reduction. ONH vessel density did not differ after CSFP reduction (all P>0.05). In conclusion, macular vessel density decreased in association with CSFP reduction. Retinal vessel density in the macular region is more sensitive than that in peripapillary region after CSFP reduction.

Cerebrospinal fluid dynamics in idiopathic intracranial hypertension: a literature review and validation of contemporary findings

BackgroundIdiopathic intracranial hypertension (IIH) is a rare disease of unknown aetiology related possibly to disturbed cerebrospinal fluid (CSF) dynamics and characterised by elevated intracranial pressure (ICP) causing optic nerve atrophy if not timely treated. We studied CSF dynamics of the IIH patients based on the available literature and our well-defined cohort.MethodA literature review was performed from PubMed between 1980 and 2020 in compliance with the PRISMA guideline. Our study includes 59 patients with clinical, demographical, neuro-ophthalmological, radiological, outcome data, and lumbar CSF pressure measurements for suspicion of IIH; 39 patients had verified IIH while 20 patients did not according to Friedman’s criteria, hence referred to as symptomatic controls.ResultsThe literature review yielded 19 suitable studies; 452 IIH patients and 264 controls had undergone intraventricular or lumbar CSF pressure measurements. In our study, the mean CSF pressure, pulse amplitudes, power of respiratory waves (RESP), and the pressure constant (P0) were higher in IIH than symptomatic controls (p < 0.01). The mean CSF pressure was higher in IIH patients with psychiatric comorbidity than without (p < 0.05). In IIH patients without acetazolamide treatment, the RAP index and power of slow waves were also higher (p < 0.05). IIH patients with excess CSF around the optic nerves had lower relative pulse pressure coefficient (RPPC) and RESP than those without (p < 0.05).ConclusionsOur literature review revealed increased CSF pressure, resistance to CSF outflow and sagittal sinus pressure (SSP) as key findings in IIH. Our study confirmed significantly higher lumbar CSF pressure and increased CSF pressure waves and RAP index in IIH when excluding patients with acetazolamide treatment. In overall, the findings reflect decreased craniospinal compliance and potentially depleted cerebral autoregulation resulting from the increased CSF pressure in IIH. The increased slow waves in patients without acetazolamide may indicate issues in autoregulation, while increased P0 could reflect the increased SSP.

Dynamics of Selected Biomarkers in Cerebrospinal Fluid During Complex Endovascular Aortic Repair – A Pilot Study

Ischemic spinal cord injury (SCI) is a serious complication of complex aortic repair. Prophylactic cerebrospinal fluid (CSF) drainage, used to decrease lumbar cerebrospinal fluid (CSF) pressure, enables monitoring of CSF biomarkers that may aid in detecting impending SCI. We hypothesized that biomarkers, previously evaluated in traumatic SCI and brain injury, would be altered in CSF over time following complex endovascular aortic repair (cEVAR). To examine if a chosen cohort of CSF biomarker correlates to SCI and warrants further research. A prospective observational study on patients undergoing cEVAR with extensive aortic coverage. Vital parameters and CSF samples were collected on ten occasions during 72 hours post-surgery. A panel of ten biomarkers were analyzed (Neurofilament Light Polypeptide (NFL), Tau, Glial Fibrillary Acidic Protein (GFAP), Soluble Amyloid Precursos Protein (APP) α and β, Amyloid β 38, 40 and 42 (Aβ38, 40 and 42), Chitinase-3-like protein 1 (CHI3LI or YKL-40), Heart-type fatty acid binding protein (H-FABP).). Nine patients (mean age 69, 7 males) were included. Median total aortic coverage was 68% [33, 98]. One patient died during the 30-day post-operative period. After an initial stable phase for the first few postoperative hours, most biomarkers showed an upward trend compared with baseline in all patients with >50% increase in value for NFL in 5/9 patients, in 7/9 patients for Tau and in 5/9 patients for GFAP. One patient developed spinal cord and supratentorial brain ischemia, confirmed with MRI. In this case, NF-L, GFAP and tau were markedly elevated compared with non-SCI patients (maximum increase compared with baseline in the SCI patient versus mean value of the maximal increase for all other patients: NF-L 367% vs 79%%, GFAP 95608% versus 3433%, tau 1020% vs 192%). This study suggests an increase in all ten studied CSF biomarkers after coverage of spinal arteries during endovascular aortic repair. However, the pilot study was not able to establish a specific correlation between spinal fluid biomarker elevation and clinical symptoms of SCI due to small sample size and event rate.

Abnormal Intracranial Pulse Pressure Amplitude Despite Normalized Static Intracranial Pressure in Idiopathic Intracranial Hypertension Refractory to Conservative Medical Therapy.

Idiopathic intracranial hypertension (IIH) incorporates symptoms and signs of increased intracranial pressure (ICP) and is diagnosed by increased lumbar cerebrospinal fluid pressure. However, our knowledge about the characteristics of ICP abnormality, e.g., changes in pulsatile versus static ICP, remains scarce. This study questioned how overnight pulsatile ICP (mean ICP wave amplitude, MWA) associates with static ICP (mean ICP) in IIH patients who were refractory to conservative medical treatment. The material included 80 consecutive IIH patients undergoing ICP monitoring prior to shunt, as part of work-up for failed conservative medical therapy. In this group, the overnight mean ICP was normalized in 52/80 patients, but with abnormal overnight MWA in 45 of the 52 patients. Even though there was a positive correlation between MWA and mean ICP at group level and within individual ICP recordings, the levels of MWA were abnormal in a high proportion of patients despite normalized mean ICP. Taken together, the present results disclosed lasting abnormal pulsatile ICP despite normalized static ICP in IIH patients refractory to conservative medical therapy, which may reflect the underlying pathophysiology. It is tentatively suggested that abnormal pulsatile ICP in IIH may reflect alterations at the glia–neurovascular interface, resulting in impaired astrocytic pulsation absorber mechanisms.

Reference values for intracranial pressure and lumbar cerebrospinal fluid pressure: a systematic review

BackgroundAlthough widely used in the evaluation of the diseased, normal intracranial pressure and lumbar cerebrospinal fluid pressure remain sparsely documented. Intracranial pressure is different from lumbar cerebrospinal fluid pressure. In addition, intracranial pressure differs considerably according to the body position of the patient. Despite this, the current reference values do not distinguish between intracranial and lumbar cerebrospinal fluid pressures, and body position-dependent reference values do not exist. In this study, we aim to establish these reference values.MethodA systematic search was conducted in MEDLINE, EMBASE, CENTRAL, and Web of Sciences. Methodological quality was assessed using an amended version of the Joanna Briggs Quality Appraisal Checklist. Intracranial pressure and lumbar cerebrospinal fluid pressure were independently evaluated and subdivided into body positions. Quantitative data were presented with mean ± SD, and 90% reference intervals.ResultsThirty-six studies were included. Nine studies reported values for intracranial pressure, while 27 reported values for the lumbar cerebrospinal fluid pressure. Reference values for intracranial pressure were − 5.9 to 8.3 mmHg in the upright position and 0.9 to 16.3 mmHg in the supine position. Reference values for lumbar cerebrospinal fluid pressure were 7.2 to 16.8 mmHg and 5.7 to 15.5 mmHg in the lateral recumbent position and supine position, respectively.ConclusionsThis systematic review is the first to provide position-dependent reference values for intracranial pressure and lumbar cerebrospinal fluid pressure. Clinically applicable reference values for normal lumbar cerebrospinal fluid pressure were established, and are in accordance with previously used reference values. For intracranial pressure, this study strongly emphasizes the scarcity of normal pressure measures, and highlights the need for further research on the matter.

Study protocol for an observational study of cerebrospinal fluid pressure in patients with degenerative cervical myelopathy undergoing surgical deCOMPression of the spinal CORD: the COMP-CORD study

IntroductionDegenerative cervical myelopathy (DCM) is a disabling spinal disorder characterised by sensorimotor deficits of upper and lower limbs, neurogenic bladder dysfunction and neuropathic pain. When suspected, cervical MRI helps to...

Anesthesia During Positive-pressure Myelogram: A New Role for Cerebral Oximetry.

Positive-pressure myelogram (PPM) is an emerging radiologic study used to localize spinal dural defects. During PPM, cerebrospinal fluid pressure (CSFp) is increased by injecting saline with contrast into the cerebrospinal fluid. This has the potential to increase intracranial pressure and compromise cerebral perfusion. We performed a retrospective chart review and analysis of 11 patients. The aim was to describe the periprocedural anesthetic management of patients undergoing PPM. All patients underwent PPM with general anesthesia and intra-arterial blood pressure and near-infrared spectroscopy monitoring of regional cerebral tissue oxygen saturation. Mean±SD maximum lumbar CSFp was 58±12 mm Hg. Upon intrathecal injection, mean systolic blood pressure increased from 115±21 to 142±32 mm Hg (P<0.001), diastolic blood pressure from 68±12 to 80±20 mm Hg (P≤0.001), and mean blood pressure from 87±10 to 98±14 mm Hg (P=0.02). Ten of 11 patients received blood pressure augmentation with phenylephrine to minimize the risk of reduced cerebral perfusion secondary to increased CSFp after intrathecal injection. The mean heart rate before and following injection was similar (68±15 vs. 70±15 bpm, respectively; P=0.16). There was a decrease in regional cerebral oxygen saturation after positioning from supine to prone position (79±10% to 74±9%, P=0.02) and a further decrease upon intrathecal injection (75±10% to 69±9%, P≤0.01). Systemic blood pressure increased following intrathecal injection during PPM, possibly due to a physiologic response to intracranial hypertension/reduced cerebral perfusion or administration of phenylephrine. Regional cerebral oxygen saturation decreased with the change to prone position and further decreased upon intrathecal injection. Cerebral near-infrared spectroscopy has a potential role to monitor the adequacy of cerebral perfusion and guide adjustment of systemic blood pressure during PPM.

Cerebrospinal Fluid Pressure-Related Features in Chronic Headache: A Prospective Study and Potential Diagnostic Implications.

Objective: To identify the pressure-related features of isolated cerebrospinal fluid hypertension (ICH) in order to differentiate headache sufferers with ICH from those with primary headache disorder.Methods: In this prospective study, patients with refractory chronic headaches and suspected of having cerebrospinal fluid-pressure elevation without papilledema or sixth nerve palsy, together with controls, underwent 1-h lumbar cerebrospinal fluid pressure monitoring via a spinal puncture needle.Results: We recruited 148 consecutive headache patients and 16 controls. Lumbar cerebrospinal fluid pressure monitoring showed high pressure and abnormal pressure pulsations in 93 (63 %) patients with headache: 37 of these patients with the most abnormal pressure parameters (opening pressure above 250 mm H2O, mean pressure 301 mm H2O, mean peak pressure 398 mm H2O, and severe abnormal pressure pulsations) had the most severe headaches and associated symptoms (nocturnal headache, postural headache, transient visual obscuration); 56 patients with the less abnormal pressure parameters (opening pressure between 200 and 250 mm H2O, mean pressure 228 mm H2O, mean peak pressure 316 mm H2O, and abnormal pressure pulsations) had less severe headaches and associated symptoms.Conclusions: Nocturnal and postural headache, and abnormal pressure pulsations are the more common pressure-related features of ICH in patients with chronic headache. Abnormal pressure pulsations may be considered a marker of ICH in chronic headache.

Relationship between the optic nerve sheath diameter and lumbar cerebrospinal fluid pressure in patients with normal tension glaucoma.

PurposeTo investigate on the relationship between the optic nerve sheath diameter (ONSD) and the lumbar cerebrospinal fluid pressure (CSF-p) in Caucasian patients with normal tension glaucoma (NTG).Patients and methodsRetrospective analysis of medical records of patients with open-angle glaucoma in the period from 2005 to 2015 from the Ophthalmology Department, Cantonal Hospital Aarau, Switzerland was performed. A total of 38 patients (mean age 68.6±11.3 years, 21 females and 17 males) fulfilled the diagnostic criteria of NTG and underwent computed tomography (CT) of the orbit and lumbar puncture (LP). In total, 38 age- and gender-matched Caucasian subjects (mean age: 68.9±10.9 years) without known ON diseases served as controls for ONSD measurements. ONSDs were measured at a distance of 3 mm from the posterior globe and lumbar CSF-p was related to the measurements. Statistical analysis was performed by using the independent two-tailed t-test and the non-parametric Spearman's correlation test.ResultsThe mean ONSD in NTGs measured 6.4±0.9 mm and in controls 5.4±0.6 mm. The difference between NTGs and controls showed statistical significance (t-test: P<0.000). The mean CSF-p in NTG was 11.6±3.7 mm Hg. There was no statistical significant correlation between ONSD and CSF-p (Spearman's correlation coefficient ρ=0.06, P=0.72).ConclusionsThis study demonstrates enlarged ONSDs and normal lumbar CSF-p in 38 Caucasian NTG patients. As enlarged ONSDs generally are associated with increased intracranial CSF-p, these results can be explained by a disturbed communication of CSF-p between the intracranial and intraorbital subarachnoid spaces.

Translaminar pressure in Caucasian normal tension glaucoma patients.

The aim of this study was to examine the translaminar pressure difference (TLP) in Caucasian patients with normal tension glaucoma (NTG) and its possible impact onto the pathogenesis of NTG. Retrospective analysis of medical records of patients with open-angle glaucoma (OAG) in the period from 2005 to 2015 from the Ophthalmology Department, Cantonal Hospital Aarau, Switzerland. A total of 67 eyes of 38 patients (mean age 68.6±11.3years, 21 women and 17 men) fulfilled the diagnostic criteria of progressive NTG and underwent lumbar puncture (LP) during computer-assisted cisternography (CT - cisternography). The intraocular pressure (IOP) and lumbar cerebrospinal fluid pressure (CSF-p) were analysed and the TLP calculated. The TLP was compared with the mean defect (MD) of visual fields. Statistical analysis was performed with the one and two-tailed paired and unpaired t-test and the non-parametric Spearman correlation test. The mean lumbar opening CSF-p measured 11.6±3.7mmHg. The mean IOP in the right eye measured 14.7±2.4mmHg, in the left eye 14.7±2.5mmHg. The calculated mean TLP was 3.0±4.2mmHg in the right and 3.3±4.3mmHg in the left eye. There was no significant correlation between TLP and the MD of visual fields in both eyes. This study did not confirm either a lower lumbar CSF-p or increased TLP compared to previous retrospective and prospective studies. As cerebrospinal fluid (CSF) flow is not homogenous throughout all CSF spaces and CSF-p and IOP fluctuate, the current view on TLP needs modifications to improve its validity.

Optical coherence tomography of the optic nerve head detects acute changes in intracranial pressure

We aimed to determine if there are measurable objective changes in the optic nerve head (ONH) immediately after cerebrospinal fluid (CSF) drainage in a prospective case-series of five patients undergoing a clinically indicated lumbar puncture (LP) for diagnosis of idiopathic intracranial hypertension. A Cirrus high-definition optical coherence tomography machine (Carl Zeiss Meditec, Dublin, CA, USA) was used to acquire images in the lateral decubitus position. Optic disc cube and high-definition line raster scans centered on the ONH were obtained immediately before and after draining CSF, while the patient maintained the lateral decubitus position. Measured parameters included retinal nerve fiber layer (RNFL) thickness, peripapillary retinal pigment epithelium/Bruch’s membrane (RPE/BM) angulation, transverse neural canal diameter (NCD) and the highest vertical point of the internal limiting membrane from the transverse diameter (papillary height). The mean (±standard deviation) opening and closing CSF pressures were 34.3±11.8 and 11.6±3.3cmH2O, respectively. Mean RNFL thickness (pre LP: 196±105μm; post LP: 164±77μm, p=0.1) and transverse NCD (pre LP: 1985±559μm; post LP: 1590±228μm, p=2.0) decreased in all subjects, but with non-significant trends. The RPE/BM angle (mean change: 5.8±2.0degrees, p=0.003) decreased in all subjects. A decrease in papillary height was seen in three of five subjects (mean: pre LP: 976±275μm; post LP: 938±300μm, p=0.9). Our results show a measurable, objective change in the ONH after acute lowering of the lumbar CSF pressure, suggesting a direct link between the lumbar subarachnoid space and ONH regions, and its potential as a non-invasive method for monitoring intracranial pressures.

Pneumocephalus following spinal anaesthesia for spine surgery.

Pneumocephalus following spinal anaesthesia for spine surgery.

Clinical Validation of a Transcranial Doppler-Based Noninvasive Intracranial Pressure Meter: A Prospective Cross-Sectional Study

Noninvasive intracranial pressure (ICP) measurement would represent a major advance for patients with neurological problems. The Vittamed ICP meter is an ultrasound-based device reported to have high agreement with lumbar puncture cerebrospinal fluid (CSF) pressure measurement. However, previous studies included mostly patients with normal levels of ICP. The purpose of our study was to perform an independent clinical validation study of a transcranial Doppler-based noninvasive ICP meter in patients anticipated to have a wide range of ICP. In a prospective cross-sectional design, we simultaneously measured ICP with the Vittamed device and the invasive lumbar CSF pressure. The operator of each procedure was blinded to the result of the other method. Data were analyzed using Bland-Altman plots, Pearson correlation coefficients, and receiver operator characteristic curves. Twenty-four independent paired measurements of Vittamed and lumbar CSF pressure were obtained; with mean absolute difference between paired measures of 4.5 mmHg (standard deviation 3.1). The 95% limits of agreement were-10.5 to+11.0. The systematic bias (mean of paired differences) was negligible at 0.25 mmHg. The sensitivity, specificity, and area under the curve for ICP >20 mmHg were 0.73, 0.77, and 0.71, respectively. The Vittamed ICP meter had fair agreement with lumbar CSF pressure measurement. The wide limits of agreement would preclude using this version of the device as a stand-alone method for ICP determination, but may be useful if combined with other ICP screening methods. Ongoing improvements to the Vittamed hardware and software may lead to improvements in accuracy and clinical utility of this device.

Dr. Ninan T. Mathew--A "Tribute" (1937-2015).

Dr. Ninan T. Mathew--A "Tribute" (1937-2015).

Comparison of pulsatile and static pressures within the intracranial and lumbar compartments in patients with Chiari malformation type 1: a prospective observational study.

In Chiari malformation type 1 (CMI), the obstruction of cerebrospinal fluid (CSF) flow through the foramen magnum is believed to cause alterations of intracranial pressure (ICP) pulsations. Foramen magnum decompression (FMD) is therefore considered a treatment of choice. However, the pathophysiology of CMI is poorly understood and it remains unknown how ICP alterations relate to symptoms and radiological findings. This study was undertaken to measure pulsatile pressure and its gradient between intracranial and lumbar compartments, and to determine its relationship to clinical and radiological findings. In patients with symptomatic CMI, we simultaneously measured ICP and lumbar CSF pressure, with particular focus on analysis of pulsatile pressure. Ventricular CSF volume (VV), intracranial volume (ICV) and posterior cranial fossa volume (PCFV) were calculated using volumetry software. In 26 patients (median 35 years), we found clearly abnormal or borderline values of pulsatile ICP in 18/26 patients (69 %; median 4.5 mmHg) and abnormal pulsatile pressure gradient in 17/24 patients (71 %; median 2.6 mmHg). The correlation between pulsatile ICP and the pulsatile pressure gradient was significantly positive (p < 0.001). We found no significant correlation between pulsatile or static pressure and extent of tonsillar ectopy, VV, ICV or PCFV. The pulsatile pressure gradient was significantly higher in patients with syringomyelia (p = 0.02). In this cohort, the pulsatile ICP was elevated in 69 %. The intracranial-lumbar pulsatile pressure gradient was abnormal in 71 % and significantly higher in patients with syringomyelia. The elevated pulsatile ICP significantly correlated with pulsatile pressure gradient; no similar correlation was found for static ICP. We interpret the results as providing evidence of impaired intracranial compliance as an important pathophysiological mechanism in CMI.