Category: CSF disorders

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Intraoperative Ultrasound in Chiari 1 Decompression: Clarity or Confusion?

Neurosurgery 99:19–29, 2026

This systematic review evaluates intraoperative ultrasound (iUS) use in guiding the extent of posterior fossa decompression (PFD versus PFD+) for Chiari malformation type 1, analyzing nine studies (844 patients) for iUS criteria, conversion rates, and positive predictive values. It finds substantial heterogeneity in acquisition, qualitative versus quantitative criteria, and outcome reporting, limiting iUS’s reliability for intraoperative decision making.

The authors propose a standardized reporting framework emphasizing defined CSF space measurements, dynamic metrics (e.g., CSF flow velocity, tonsillar excursion), triplicate measurements with dual raters, and ≥12-month validated outcomes to enable reproducible research and clearer assessment of iUS utility.

Clinical dilemma Bone-only posterior fossa decompression (PFD) is less invasive, while dural opening/expansion (PFD+) may be more effective but has higher complication risk; intraoperative ultrasound (iUS) is used to help decide whether PFD alone is sufficient, but its role/criteria are not defined.

Evidence base 9 studies (1 prospective, 8 retrospective) totaling 844 patients (pediatric and adult) were included; risk of bias was low in 1 study, moderate in 3, and high in 5.

How iUS was applied iUS was used after bony decompression and before dural opening; none of the studies used iUS after opening the dura.

Decision criteria heterogeneity 8 studies used qualitative criteria (e.g., “enough space,” tonsillar pulsation, piston-like motion, bidirectional flow), and 1 study used a quantitative CSF flow-velocity threshold.

Conversion surgery outcomes “Conversion” (later revision from PFD to PFD+ due to persistent/worsening symptoms) occurred in 35/844 patients (5% overall), with study-level conversion rates from 0% to 16%.

Predictive value variability Positive predictive value (PPV) for iUS-guided PFD success ranged from 0.857 to 1.000 across studies, varying with criteria and study design.

Main conclusion Current evidence does not support iUS as a robust intraoperative test for deciding extent of decompression because of heterogeneous application and lack of standardized assessment criteria; sensitivity/specificity cannot be determined with available data structure.

Proposed path forward A standardized reporting framework is proposed, emphasizing defined acquisition parameters, quantitative/operationalized criteria, validated outcome measures, and ≥12-month follow-up to enable comparability and future pooled analyses.

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Morphometric assessment of the posterior cranial fossa and its contents in patients with chiari malformation type I and type 0

Acta Neurochirurgica (2026) 168:117

This study presents a retrospective, landmark-based morphometric analysis of the clivus, tentorium, and posterior cranial fossa on midsagittal MRI in 326 subjects, comparing Chiari malformation Type I (CM-I), Chiari Type 0 (CM-0), and matched controls. Key measured parameters include clivus length and angle, tentorial angle, foramen magnum diameter, and area-based ratios relating cerebellum, posterior fossa, and intracranial cavity.

Findings indicate that CM-I patients exhibit clival shortening, reduced posterior cranial fossa area, altered tentorial orientation, and increased cerebellar occupancy relative to posterior fossa and brain, whereas CM-0 patients show morphometry comparable to controls. The authors conclude CM-I has distinct morphoanatomical remodeling, while CM-0 may represent a functional clinical entity without consistent structural substrate.

Definitions: CM-I is defined by ≥5 mm cerebellar tonsillar descent below the foramen magnum on MRI, while CM-0 is defined by <3 mm descent despite Chiari-like symptoms.

Design: Retrospective mid-sagittal MRI morphometry of 326 adults (CM-I n=111, CM-0 n=27, controls n=188) using multiple cranial base, posterior fossa, cerebellar, and intracranial measurements plus area-based ratios.

Key CM-I anatomy: Compared with CM-0 and controls, CM-I showed shorter clivus length, smaller posterior cranial fossa area, and larger cerebellar area; foramen magnum diameter and total brain area were similar across groups.

Crowding ratios: CM-I had higher cerebellum/posterior fossa and cerebellum/brain area ratios, indicating increased relative cerebellar occupancy despite preserved global cranial proportions.

CM-0 vs controls: CM-0 morphometric measurements were largely comparable to healthy controls, with no consistent structural differences in the main posterior fossa metrics highlighted.

Interpretation: CM-I aligns with a pattern of cranial base remodeling and posterior fossa insufficiency, whereas CM-0 may be better viewed as a functionally defined condition rather than one with a consistent structural substrate.

Reliability/statistics: Analyses used nonparametric tests (Kruskal–Wallis with Bonferroni-corrected Mann–Whitney post hoc), and interobserver measurement reliability was good–excellent (ICC 0.82–0.94).

Limitations: Morphometry was 2D mid-sagittal (not full 3D volumetry) and CSF flow dynamics (e.g., phase-contrast MRI) were not uniformly available, limiting functional assessment—especially relevant to CM-0.

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Health-Related Quality-of-Life Outcomes in Surgical Patients With Sacral Tarlov Cysts: A 2-Year Prospective Study

Neurosurgery 98:1156–1165, 2026

This prospective longitudinal study reports clinical and patient-reported health-related quality-of-life outcomes for 417 adults who underwent surgical treatment for symptomatic sacral Tarlov cysts, with standardized assessments at baseline and 3, 6, 12, and 24 months. Using the disease-specific TCQoL alongside SF-36, ODI, and VAS, the study demonstrates statistically significant and clinically meaningful improvements across most domains, low complication rates, and no radiographic cyst recurrence at early follow-up.

The authors detail a microsurgical posterior sacral laminectomy technique with cyst decompression, dural sleeve wrapping, and laminar reconstruction, and report sustained benefits through 2 years, including increased tolerated sitting time and reduced opioid use. Limitations include attrition and missing data addressed by imputation, and the paper advocates broader adoption of the TCQoL for standardized Tarlov cyst research.

Study aim Assess whether surgical treatment for symptomatic sacral Tarlov cysts improves validated general and disease-specific health-related quality of life (HRQoL) through 2 years post-op, and whether outcomes change from year 1 to year 2.

Design & cohort Retrospective analysis of prospectively collected longitudinal outcomes for adults undergoing first-time surgery for ≥1 sacral Tarlov cyst (2008–2023), performed by a single neurosurgeon; 417 patients (mean age 52.5, 91.1% female).

Outcome measures Primary outcome was the TCQoL (11-item disease-specific scale); secondary measures included VAS pain (rest/activity), ODI, and SF-36, collected pre-op and at 3, 6, 12, and 24 months.

Surgical technique Posterior sacral laminectomy with microsurgical dissection, cyst drainage to normalize root caliber, wrapping the cystic nerve root with bovine pericardium dural substitute sleeve to limit refilling, and covering the laminar window with a resorbable plate/screws.

2-year improvements (key metrics) Significant improvements from pre-op to 2 years in TCQoL (3.2→2.1), VAS pain at rest (4.5→2.3) and activity (5.7→3.1), and ODI (45.5→31.6) (all P<.001).

SF-36 domains Improvement occurred in 7/8 SF-36 scales (Physical Functioning, Physical Limitations, Bodily Pain, Vitality, Social Functioning, Emotional Limitations, Mental Health), while General Health was not statistically significant in the imputed analysis.

Year 1 to year 2 change Most subscales did not change significantly from 1 to 2 years; significant further gains were seen in physical functioning and social functioning (P=.040 and P=.016, respectively).

Sitting tolerance Median tolerated sitting time increased from 15 minutes pre-op to 45 minutes at 2 years post-op.

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Suprasellar Versus Third Ventricular Cysts: Anatomic and Surgical Considerations

Operative Neurosurgery 30:468–471, 2026

This surgical case instruction contrasts suprasellar arachnoid cysts (SACs) and third ventricular cysts (3VCs), emphasizing their distinct imaging features, clinical presentations, and risks of obstructive hydrocephalus. It summarizes patient examples, MRI findings, and outcomes after endoscopic cyst fenestration, demonstrating restoration of cerebrospinal fluid flow and symptom resolution.

The article details stepwise endoscopic techniques—cyst plane development, wall reduction, excision, and membrane management—highlighting anatomical cues that guide whether endoscopic third ventriculostomy is necessary. Practical tips on preserving hypothalamic structures, restoring aqueduct patency, and minimizing reaccumulation are provided for neurosurgical practice.

Prevalence Intracranial arachnoid cysts occur in ~2.6% of children and ~1.4% of adults; suprasellar arachnoid cysts (SACs) comprise ~9%–21% of pediatric arachnoid cysts and can be confused with rarer third ventricular cysts (3VCs).

Presentation SACs and 3VCs often enlarge and cause obstructive hydrocephalus with symptoms of increased intracranial pressure, prompting urgent treatment to restore CSF circulation.

Imaging differences (SAC) SACs elevate the third ventricular floor, displace mammillary bodies superiorly/posteriorly, and elongate/stretch the midbrain and aqueduct, with aqueduct occlusion from distortion and the posterior cyst wall.

Imaging differences (3VC) 3VCs displace the third ventricular floor and mammillary bodies inferiorly with midbrain compaction; the aqueduct is obstructed by midbrain distortion and the inferoposterior cyst wall.

Treatment rationale A shunt without cyst fenestration can lead to asymmetric hydrocephalus and/or continued cyst enlargement due to cyst-related occlusion of the foramina of Monro; neuroendoscopy enables cyst fenestration with low morbidity risk at experienced centers.

Endoscopic steps A stepwise intraventricular endoscopic approach includes: developing the cyst/ventricle plane; reducing cyst wall size (coagulation); excising roof/lateral/medial walls (with caution laterally in SACs due to hypothalamic fusion); removing/reducing floating membranes (especially posteriorly) to open access to the aqueduct.

Inferior wall strategy In SACs, inferior membrane fenestration may be unnecessary because the prepontine cistern is already exposed/communicates with the third ventricle; in 3VCs, the inferior aspect is the third ventricular floor, and endoscopic third ventriculostomy (ETV) is an option.

ETV decision point If posterior membrane resection fully restores aqueduct patency, ETV may not be necessary; reducing expansile membranes is pursued to lower risk of reaccumulation from scarring.

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A Multicenter Study of Noninvasive Wireless Assessment of Cerebrospinal Fluid Shunt Function in Hydrocephalus Patients

Neurosurgery 97:1397–1405, 2025

This multicenter prospective study evaluates a wearable, wireless thermal anisotropy sensor for noninvasive detection of cerebrospinal fluid (CSF) shunt flow in symptomatic hydrocephalus patients. Using a random forest algorithm on data from 112 validated subjects, the device showed high sensitivity (88.9%) and a very high negative predictive value (96.8%), though specificity was modest (49.2%) and a 37.5% no-result rate occurred.

Methods, usability, and comparative analyses are detailed: device design, algorithm development, blinded validation, and 7-day surgical follow-up with intraoperative confirmation as ground truth. Ease-of-use was rated highly, adverse events were minor skin reactions, and combined use with CT/MRI improved specificity and overall accuracy, supporting adjunctive clinical application.

Device Purpose: A novel, noninvasive, wireless wearable device was developed to assess cerebrospinal fluid (CSF) shunt flow in hydrocephalus patients presenting with possible shunt failure, using thermal anisotropy measurements to detect flow through the shunt tubing.

Study Design: The prospective, blinded, multicenter study included both pediatric and adult patients with existing ventriculoperitoneal shunts and symptoms suggestive of shunt failure; subjects underwent device evaluation alongside standard-of-care assessments.

Algorithm Performance: The device’s random forest algorithm demonstrated high sensitivity (88.9%) and negative predictive value (NPV, 96.8%) but moderate specificity (49.2%) for detecting complete shunt failure, indicating strong ability to rule out failure when flow is confirmed.

Clinical Utility: The high NPV suggests the device could help identify patients whose shunts are functioning, potentially reducing unnecessary surgical interventions or additional invasive tests.

Comparison with Standard Tests: Standard imaging tests (CT/MRI) showed moderate-to-high sensitivity and specificity but require radiation or sedation, whereas the device is noninvasive, wireless, and does not require such resources.

Combined Diagnostic Approach: When device results were combined with CT or MRI findings, specificity increased to 93.3% and NPV to 96.6%, supporting a potential workflow where the device is used to complement imaging for risk stratification.

Safety and Usability: The device was rated as easy to use by clinicians, with a low rate of mild, self-resolving skin redness and no serious adverse events reported.

Limitations: The device is not suitable as a stand-alone diagnostic tool due to moderate specificity and a substantial rate of incomplete measurements; further studies are ongoing to optimize performance and generalizability.

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Surgical outcomes for spinal arachnoid cysts and webs: a case series

Acta Neurochirurgica (2025) 167:248

This retrospective case series found that surgical treatment for spinal arachnoid cysts (SAC) and webs (SAW) resulted in favorable outcomes (mMC I-II) in 90% and 83% of patients, respectively, with low complication and recurrence rates. Surgery should be considered for symptomatic patients.

• Spinal arachnoid cysts (SAC) and spinal arachnoid webs (SAW) are rare intradural pathologies causing pain and myelopathic symptoms.

• MRI is the main diagnostic tool, but distinguishing between SAC and SAW can be difficult; both may show the “scalpel sign”.

• This retrospective study reviewed 35 patients (29 SAC, 6 SAW) treated surgically from 2011–2023.

• Most patients presented with pain, gait disturbance, sensory, or motor deficits; preoperative neurological status was often not severe.

• Surgical treatment (fenestration or resection) led to favorable outcomes (mMC I-II) in 90% of SAC and 83% of SAW patients.

• Complications occurred in 14.7% of SAC cases but resolved without lasting deficits; no complications in SAW group.

• Recurrence was rare (2.7% in SAC, none in SAW) during short-term follow-up.

• Surgery is recommended for symptomatic patients, with generally favorable short-term results, but larger and longer-term studies are needed.

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Predecompression and postdecompression cognitive and affective changes in Chiari malformation type I

J Neurosurg 143:4–12, 2025

This prospective study found that patients with Chiari malformation type I commonly experience cognitive and psychiatric impairments, particularly in executive function and visuospatial memory. Following posterior fossa decompression surgery, 89% showed significant improvement in cognitive and/or psychiatric symptoms, highlighting the cerebellum’s role in these functions.

• Chiari malformation type I (CM-I) patients often have unrecognized cognitive and psychiatric symptoms, including deficits in executive function, visuospatial memory, and increased depression, anxiety, and related symptoms.

• This prospective study assessed 54 CM-I patients with cognitive or psychiatric complaints before and after posterior fossa decompression (PFD) surgery.

• Preoperatively, patients performed worse than normative samples in executive function and visuospatial memory, and reported more psychiatric symptoms across all measured domains.

• Six months after surgery, 89% of patients showed clinically significant improvements (>1 SD) in cognitive and/or psychiatric domains.

• Improvements were most notable in visuospatial memory and psychiatric symptoms such as depression and anxiety, which normalized to levels seen in the general population.

• Patients with the most severe preoperative deficits experienced the greatest postoperative improvements.

• The findings support a key role for the cerebellum in cognitive and psychiatric dysfunction and suggest that some symptoms in CM-I are potentially treatable with targeted cerebellar intervention.

• Limitations include lack of a control group and focus on symptomatic, self-reporting patients, so results may not generalize to all CM-I cases.

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Comprehensive Morphometric Analysis to Identify Key Neuroimaging Biomarkers for the Diagnosis of Adult Hydrocephalus Using Artificial Intelligence

Neurosurgery 96:1386–1396, 2025

This study used AI and SHAP analysis to identify five key, easily measurable 1-D neuroimaging biomarkers—FTHR, MEI, MCMI, SMLH, and CPCA—for accurately diagnosing adult non-normal pressure hydrocephalus, offering a practical, standardized, and interpretable approach to improve early detection and clinical decision-making.

• Hydrocephalus diagnosis is often inconsistent due to reliance on clinical and qualitative radiological assessments.

• This study used artificial intelligence (AI) and SHAP analysis to identify key, easily measurable neuroimaging biomarkers for adult non-normal pressure hydrocephalus (non-NPH).

• A comprehensive set of 21 morphometric features was analyzed from MRI images of 42 adult non-NPH patients and 40 healthy controls.

• Gradient Boosting was the best-performing AI classifier, achieving 0.94 accuracy and 0.97 AUC.

• Ventricular volume is the most important biomarker, but measurement is complex for clinicians.

• Five key 1-D biomarkers identified are: frontal-temporal horn ratio (FTHR), modified Evans index (MEI), modified cella media index (MCMI), sagittal maximum lateral ventricle height (SMLH), and coronal posterior callosal angle (CPCA).

• These five markers are easily measurable and provide high diagnostic accuracy, supporting practical clinical use.

• The approach addresses multicollinearity and improves diagnostic standardization, but further validation with larger datasets is needed.

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Microsurgical Repair of Ventral Cerebrospinal Fluid Leaks in Spontaneous Intracranial Hypotension: Efficacy and Safety of Patch-Sealing Versus Suturing

 

Operative Neurosurgery 28:379–385, 2025

This study compares microsurgical suturing and patch-sealing techniques for repairing ventral cerebrospinal fluid leaks in spontaneous intracranial hypotension. Both methods are equally effective, but sealing is faster and involves less spinal cord manipulation, potentially reducing surgical complications.

Study Overview and Methods

• Compared microsurgical suture vs. patch-sealing for ventral dural leaks in SIH patients.

• Retrospective analysis conducted between 2013 and 2023 at a single center.

• 85 patients with Type 1 SIH leaks were included in the study.

Results

• No significant difference in headache resolution between techniques (89% vs 94%).

• Sealing technique was significantly faster than suturing (139 vs 169 minutes).

• Complication rates: 23% in suture group, 9% in sealing group (not statistically significant).

Clinical Outcomes

• No significant difference in postoperative Bern-Score between techniques.

• SLEC-positive postoperative rate: 13% in suture group, 22% in sealing group.

• 90% of patients reported headache improvement post-surgery.

Discussion

• Both techniques are effective, but sealing minimizes spinal cord manipulation.

• Sealing preferred due to faster surgery time and fewer complications.

• Limitations include retrospective design and potential selection bias.

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Noninvasive evaluation of the glymphatic system in diffuse gliomas using diffusion tensor image analysis along the perivascular space

J Neurosurg 142:187–196, 2025

The aim of this study was to noninvasively explore the glymphatic system (GS) in glioma and its association with glioma characteristics and prognosis by using diffusion tensor image analysis along the perivascular space (ALPS).

METHODS In the period from April 2015 to November 2021, all patients with pathologically confirmed unihemispheric glioma who had not undergone surgery, chemotherapy, radiotherapy, or stereotactic biopsy; who did not have severe brain deformation; who had undergone preoperative conventional and advanced whole-brain diffusion-weighted imaging; and whose data were available and uncompromised were included in this study. Age- and sex-matched healthy controls (HCs) who had undergone diffusion-weighted imaging were also included. The ALPS index was calculated based on diffusivity maps, allowing noninvasive analysis of the GS. The contralateral ALPS index was measured in all glioma patients, and the ipsilateral ALPS index was measured in glioma patients without severe deformation of the ipsilateral hemisphere. The ALPS index was compared between glioma patients and HCs according to tumor grade, IDH genotype, tumor and edema volume, and tumor location. The association between the bilateral ALPS index of gliomas and tumor characteristics was further analyzed. Survival analysis was conducted using Kaplan-Meier survival curves with the logrank test and univariable and multivariable Cox regressions.

RESULTS Ninety-one patients with unihemispheric glioma (33 female, mean age 46 ± 13 years) and 59 age- and sex-matched HCs were included in this study. The ipsilateral ALPS index decreased in the glioma group versus the HC group, regardless of tumor grade, IDH genotype, tumor and edema volume, or tumor location (p ≤ 0.048), whereas the contralateral ALPS index decreased in gliomas with a high grade, IDH wildtype, larger edema volume, different tumor volumes and locations (p ≤ 0.009). The ipsilateral versus contralateral ALPS index was lower regardless of tumor grade, IDH genotype, tumor and edema volume, or tumor location (p ≤ 0.044). Univariable linear regression revealed age (β = −0.004, p = 0.026), tumor grade (β = −0.114, p = 0.011), and IDH genotype (β = 0.120, p = 0.008) were associated with the ipsilateral ALPS index in glioma. Age (β = −0.005, p < 0.001), tumor grade (β = −0.144, p < 0.001), IDH genotype (β = 0.154, p < 0.001), tumor volume (β = −0.002, p = 0.001), and peritumoral edema volume (β = −0.002, p < 0.001) were correlated with the contralateral ALPS index in glioma. Multivariable linear regression revealed that tumor grade (β = −0.125, p = 0.005) was independently associated with the ipsilateral ALPS index. Age (β = −0.003, p = 0.022), IDH status (β = 0.132, p = 0.001), and tumor volume (β = −0.002, p < 0.001) were independently associated with the contralateral ALPS index. Kaplan-Meier analysis showed different survival times between low and high contralateral ALPS groups (log-rank = 10.574, p = 0.001). Univariable Cox regression analysis demonstrated that the lower contralateral ALPS index was related to a shorter survival time (HR 0.095, p = 0.005). Multivariable Cox regression analysis revealed IDH status as the only independent factor for survival (HR 0.138, p < 0.001).

CONCLUSIONS GS function was impaired in glioma and correlated with tumor characteristics, and worse contralateral GS function was associated with a shorter survival time.

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The human craniospinal venous system and its influence on postural intracranial pressure: a review

J Neurosurg 141:1484–1493, 2024

The cerebral and spinal venous systems have similar functions but unique anatomical and physiological properties. CSF occupies space in the cranial and spinal vaults, is continuously produced, and has many roles, including maintaining a favorable environment for CNS structures. The influence of the cerebrospinal venous system on CSF dynamics has been theorized since the 1940s. Newer studies suggest venous outflow pattern alterations in response to changes in body position. However, the relationship of postural cerebrospinal venous outflow shifts with and their influence on CSF homeostasis is not well understood.

METHODS The authors searched the published literature related to the anatomy and function of vertebral venous plexus (VVP), CSF, and positional cerebral venous flow characteristics. A comprehensive collection of literature was compiled and reviewed, and the relationship between cerebrospinal and venous system changes and alterations in body positions, with an emphasis on the craniocervical system, is discussed.

RESULTS The VVP is a network of valveless veins extending from the sacrum to the cranium that are interconnected with the cranial dural sinuses. The internal VVP occupies space within the extradural spinal canal and functions to return spinal venous blood to the heart, but it has additional properties, including the capability of bidirectional venous flow, an intraspinal dilatory capacity, and a role in cerebral venous outflow. When one rises to the upright position, CSF shifts toward the spinal canal and force vectors change, leading to reduced intracranial CSF pressure; simultaneously, cerebral venous outflow shifts from the jugular vein to the VVP outflow pathway. The venous outflow shift mechanism and its purpose are poorly understood. The authors review the known physiology of the system, identify gaps in knowledge to direct future research, and propose an interpretation of these data, concluding that position-dependent CSF and cerebrospinal venous shifts are part of a complementary positional craniospinal pressure regulation system that must be kept in balance for optimal CNS function.

CONCLUSIONS Current knowledge of the cerebrospinal venous anatomy, dynamic flow characteristics in response to gravity, and the venous system’s influence on CSF suggests that the VVP plays a role in influencing CSF pressure, and the authors hypothesize that it plays a role in supporting intracranial pressure in the upright body posture. Further research is needed to better characterize the functional relationship of the VVP to CSF dynamics as well as identify potentially related disease states.

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Targeted Epidural Blood Patch Injection Through a Mini-Open Approach for Treatment of Spontaneous Intracranial Hypotension

Operative Neurosurgery 26:398–405, 2024

Spontaneous intracranial hypotension is recognized as a cause for refractory headache. Treatment can range from blind blood patch injection to microsurgical repair of the cerebrospinal fluid (CSF) leak. The objective of the study was to investigate the safety and efficacy of the targeted blood patch injection (TBPI) technique through a mini-open approach in treatment of refractory intracranial hypotension.

METHODS: We retrospectively reviewed cases of 20 patients who were treated for spontaneous intracranial hypotension at our institute between 2011 and 2022. Head and spine MRI and whole-spine myelography were performed in an attempt to localize the CSF leak. All patients underwent implantation of two epidural drains above and beneath the index level through a minimally invasive interlaminar microsurgical approach under general anesthesia. Then, blood patch was injected under clinical surveillance. Treatment success and surgical complications were evaluated postoperatively and at follow-up.

RESULTS: Patients presented with orthostatic headache, vertigo, sensory deficits, and hypacusis (95%, 15%, 15%, and 10%, respectively). Subdural effusions were present in 65% of the cases. A CSF leak was identified in all patients. The exact site of the CSF leak could be identified in 80% of cases. TBPI was performed with an average blood amount of 37.5 mL. A significant improvement of symptoms was reported in 90% of the cases. A total of 15% of the patients showed recurrent symptoms and underwent a second TBPI, resulting in symptom relief. No therapy-related complications were reported.

CONCLUSION: TBPI is a safe and efficient treatment for spontaneous intracranial hypotension. It is performed in a minimally invasive procedure and can be repeated, if necessary, with a very low-risk profile.

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Noninvasive assessment of glymphatic dysfunction in idiopathic normal pressure hydrocephalus with diffusion tensor imaging

J Neurosurg 140:612–620, 2024

Diffusion tensor imaging (DTI) along the perivascular space (ALPS) (DTI-ALPS)—by calculating the ALPS index, a ratio accentuating water diffusion in the perivascular space—has been proposed as a noninvasive, indirect MRI method for assessing glymphatic function. The main aim of this study was to investigate whether DTI-ALPS would reveal glymphatic dysfunction in idiopathic normal pressure hydrocephalus (iNPH) and whether the ALPS index was associated with disease severity.

METHODS Thirty iNPH patients (13 men; median age 77 years) and 27 healthy controls (10 men; median age 73 years) underwent MRI and clinical assessment with the Timed Up and Go test (TUG) and Mini-Mental State Examination (MMSE); only the patients were evaluated with the Hellström iNPH scale. MRI data were analyzed with the DTI-ALPS method and Radscale screening tool.

RESULTS: iNPH patients showed significantly lower mean ALPS index scores compared with healthy controls (median [interquartile range] 1.09 [1.00–1.15] vs 1.49 [1.36–1.59], p < 0.001). Female healthy controls showed significantly higher ALPS index scores than males in both hemispheres (e.g., right hemisphere 1.62 [1.47–1.67] vs 1.33 [1.14–1.41], p = 0.001). This sex difference was not seen in iNPH patients. The authors found a moderate exponential correlation between mean ALPS index score and motor function as measured with time required to complete TUG (r = −0.644, p < 0.001), number of steps to complete TUG (r = −0.571, p < 0.001), 10-m walk time (r = −0.637, p < 0.001), and 10-m walk steps (r = −0.588, p < 0.001). The authors also found a positive linear correlation between mean ALPS index score and MMSE score (r = 0.416, p = 0.001). Simple linear regression showed a significant effect of diagnosis (B = −0.39, p < 0.001, R 2 = 0.459), female sex (B = 0.232, p = 0.002, R 2 = 0.157), and Evans index (B = −4.151, p < 0.001, R 2 = 0.559) on ALPS index. Multiple linear regression, including diagnosis, sex, and Evans index score, showed a higher predictive value (R 2 = 0.626) than analysis of each of these factors alone.

CONCLUSIONS The ALPS index, which was significantly decreased in iNPH patients, could serve as a marker of disease severity, both clinically and in terms of neuroimaging. However, it is important to consider the significant influence of biological sex and ventriculomegaly on the ALPS index, which raises the question of whether the ALPS index solely reflects glymphatic function or if it also encompasses other types of injury. Future studies are needed to address potential confounding factors and further validate the ALPS method.

 

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Ventriculosinus shunt: a pilot study to investigate new technology to treat hydrocephalus and mimic physiological principles of cerebrospinal fluid drainage

J Neurosurg 139:1412–1419, 2023

Devices draining CSF to the intracranial venous sinus for the treatment of hydrocephalus have been tested in the past, and while clinically effective, have not shown efficacy in the long term. The majority of these devices become obstructed within 3 months due to endothelial overgrowth. In this study, the authors investigated a newly developed ventriculosinus (VS) shunt outlet device with the objective of showing it would remain patent for at least 6 months.

METHODS Twelve patients in need of shunting for hydrocephalus underwent an operation using the investigational device and were followed for 6 months to record patency of the shunt.

RESULTS In 10 patients, the shunt was patent at 6 months, with the outlet device remaining unobstructed. In the remaining 2 patients, one died just before reaching the 6-month endpoint, and in the other the outlet was misplaced during surgery and therefore ceased to function after 3 months. No occlusion of the internal jugular vein or thrombus formation was noted in any of the 12 cases.

CONCLUSIONS These findings indicate that the outlet device can remain patent and has the capability to mimic physiological drainage by diverting CSF to the intracranial sinus. Additional confirmation of its potential as part of a new VS shunt system and ultimately as a viable alternative for ventriculoperitoneal and ventriculoatrial shunting to reduce complication rates requires further clinical trials.

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HummingFlow: novel single twist-drill access for ventricular drainage, irrigation, monitoring, and automated local drug delivery in subarachnoid hemorrhage

J Neurosurg 139:1036–1041, 2023

The management of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage (aSAH) remains one of the most important targets for neurocritical care. Advances in monitoring technology have facilitated a more thorough understanding of the pathophysiology and therapeutic approaches, but interventions are generally limited to either systemic therapies or passive CSF drainage. The authors present a novel approach that combines a multimodal monitoring bolt-based system with an irrigating ventricular drain capable of delivering intrathecal medications and describe their early experience in patients with aSAH.

METHODS The authors performed a retrospective review of cases treated with the combined Hummingbird multimodal bolt system and the IRRAflow irrigating ventriculostomy.

RESULTS Nine patients were treated with the combined multimodal bolt system with irrigating ventriculostomy approach. The median number of days to clearance of the third and fourth ventricles was 3 days in patients with obstructive intraventricular hemorrhage. Two patients received intrathecal alteplase for intraventricular hemorrhage clearance, and 2 patients received intrathecal nicardipine as rescue therapy for severe symptomatic angiographic vasospasm.

CONCLUSIONS Combined CSF drainage, irrigation, multimodality monitoring, and automated local drug delivery are feasible using a single twist-drill hole device. Further investigation of irrigation settings and treatment approaches in high-risk cases is warranted.

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Syringopleural shunt for refractory syringomyelia

Acta Neurochirurgica (2023) 165:3039–3043

Surgical treatment of syringomyelia isdirected at the reconstruction of the subarachnoid space and restoration normal cerebrospinal fluid flow. Direct intervention on the syrinx is a rescue procedure and should be offered to patients with refractory syringomyelia.

Methods We provide an overview on indications and technique of syringopleural shunt (SPS). The procedure involves the connection of syrinx with the pleural space using a lumboperitoneal shunt. The occurrence of a negative pressure inside the pleural compartment offers an appropriate gradient for drainage from the syrinx.

Conclusions The SPS allows for a safe and effective treatment of persistent syringomyelia when management of the underlying cause does not yield substantial improvement.

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The benefits of automated CSF drainage in normal pressure hydrocephalus

Acta Neurochirurgica (2023) 165:1505–1509

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 overdrainage 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.

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The value of ventricular measurements in the prediction of shunt dependency after aneurysmal subarachnoid hemorrhage

Acta Neurochirurgica (2023) 165:1545–1555

Chronic hydrocephalus requiring shunt placement is a common complication of aneurysmal subarachnoid hemorrhage (SAH). Different risk factors and prediction scores for post-SAH shunt dependency have been evaluated so far. We analyzed the value of ventricle measurements for prediction of the need for shunt placement in SAH patients.

Methods Eligible SAH cases treated between 01/2003 and 06/2016 were included. Initial computed tomography scans were reviewed to measure ventricle indices (bifrontal, bicaudate, Evans’, ventricular, Huckman’s, and third ventricle ratio). Previously introduced CHESS and SDASH scores for shunt dependency were calculated. Receiver operating characteristic analyses were performed for diagnostic accuracy of the ventricle indices and to identify the clinically relevant cut-offs.

Results Shunt placement followed in 221 (36.5%) of 606 patients. In univariate analyses, all ventricular indices were associated with shunting (all: p<0.0001). The area under the curve (AUC) ranged between 0.622 and 0.662. In multivariate analyses, only Huckman’s index was associated with shunt dependency (cut-off at ≥6.0cm, p<0.0001) independent of the CHESS score as baseline prediction model. A combined score (0–10 points) containing the CHESS score components (0–8 points) and Huckman’s index (+2 points) showed better diagnostic accuracy (AUC=0.751) than the CHESS (AUC=0.713) and SDASH (AUC=0.693) scores and the highest overall model quality (0.71 vs. 0.65 and 0.67), respectively.

Conclusions Ventricle measurements are feasible for early prediction of shunt placement after SAH. The combined prediction model containing the CHESS score and Huckman’s index showed remarkable diagnostic accuracy regarding identification of SAH individuals requiring shunt placement. External validation of the presented combined CHESS-Huckman score is mandatory.

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Minimally invasive surgery for spinal cerebrospinal fluid leaks in spontaneous intracranial hypotension

J Neurosurg Spine 38:147–152, 2023

Spinal CSF leaks cause spontaneous intracranial hypotension (SIH). Surgical closure of spinal CSF leaks is the treatment of choice for persisting leaks. Surgical approaches vary, and there are no studies in which minimally invasive techniques were used. In this study, the authors aimed to detail the safety and feasibility of minimally invasive microsurgical sealing of spinal CSF leaks using nonexpandable tubular retractors.

METHODS Consecutive patients with SIH and a confirmed spinal CSF leak treated at a single institution between April 2019 and December 2020 were included in the study. Surgery was performed via a dorsal 2.5-cm skin incision using nonexpandable tubular retractors and a tailored interlaminar fenestration and, if needed, a transdural approach. The primary outcome was successful sealing of the dura, and the secondary outcome was the occurrence of complications.

RESULTS Fifty-eight patients, 65.5% of whom were female (median age 46 years [IQR 36–55 years]), with 38 ventral leaks, 17 lateral leaks, and 2 CSF venous fistulas were included. In 56 (96.6%) patients, the leak could be closed, and in 2 (3.4%) patients the leak was missed because of misinterpretation of the imaging studies. One of these patients underwent successful reoperation, and the other patient decided to undergo surgery at another institution. Two other patients had to undergo reoperation because of insufficient closure and a persisting leak. The rate of permanent neurological deficit was 1.7%, the revision rate for a persisting or recurring leak was 3.4%, and the overall revision rate was 10.3%. The rate of successful sealing during the primary closure attempt was 96.6% and 3.4% patients needed a secondary attempt. Clinical short-term outcome at discharge was unchanged in 14 patients and improved in 25 patients, and 19 patients had signs of rebound intracranial hypertension.

CONCLUSIONS Minimally invasive surgery with tubular retractors and a tailored interlaminar fenestration and, if needed, a transdural approach is safe and effective for the treatment of spinal CSF leaks. The authors suggest performing a minimally invasive closure of spinal CSF leaks in specialized centers.

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Cerebrospinal Fluid Shunting for Idiopathic Intracranial Hypertension: A Systematic Review, Meta-Analysis, and Implications for a Modern Management Protocol

Neurosurgery 91:529–540, 2022

Cerebrospinal fluid (CSF) shunting is widely used in refractory idiopathic intracranial hypertension (IIH). Although multiple reviews have assessed its efficacy compared with other surgical treatments, there is no detailed analysis that evaluates the clinical outcomes after CSF shunting.

OBJECTIVE: To conduct a meta-analysis of the clinical impact of CSF shunting for refractory IIH and use this in conjunction with existing information on other treatment modalities to develop a modern management protocol.

METHODS: PubMed and Embase were systematically searched for studies describing CSF shunting for medically refractory IIH. Relevant information including study characteristics, patient demographics, clinical outcomes, periprocedural complications, and long-term outcomes were subjected to meta-analysis.

RESULTS: Fifteen studies published between 1988 and 2019 met our inclusion and exclusion criteria, providing 372 patients for analysis. The mean age was 31.2 years (range 0.5-71) with 83.6% being female. The average follow-up was 33.9 months (range 0-278 months). The overall rate of improvement in headache, papilledema, and visual impairment was 91% (95% CI 84%-97%), 96% (95% CI 85%-100%), and 85% (95% CI 72%95%), respectively. Of 372 patients, 155 had 436 revisions; the overall revision rate was 42% (95% CI 26%-59%). There was no significant correlation between average follow-up duration and revision rates in studies (P = .627). Periprocedural low-pressure headaches were noted in 74 patients (20%; 95% CI 11%-32%).

CONCLUSION: CSF shunting for IIH is associated with significant improvement in clinical symptoms. Shunting rarely causes periprocedural complications except overdrainagerelated low-pressure headache. However, CSF shunting has a relatively high revision rate.

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