Putting 'CSF-Shift Edema' Hypothesis to Test: Comparing Cisternal and Parenchymal Pressures After Basal Cisternostomy for Head Injury

The glymphatic system for neurosurgeons: a scoping review

The discovery of the glymphatic system has revolutionized our understanding of cerebrospinal fluid (CSF) circulation and interstitial waste clearance in the brain. This scoping review aims to synthesize the current literature on the glymphatic system's role in neurosurgical conditions and its potential as a therapeutic target. We conducted a comprehensive search in PubMed and Scopus databases for studies published between January 1, 2012, and October 31, 2023. Studies were selected based on their relevance to neurosurgical conditions and glymphatic function, with both animal and human studies included. Data extraction focused on the methods for quantifying glymphatic function and the main results. A total of 67 articles were included, covering conditions such as idiopathic normal pressure hydrocephalus (iNPH), idiopathic intracranial hypertension (IIH), subarachnoid hemorrhage (SAH), stroke, intracranial tumors, and traumatic brain injury (TBI). Significant glymphatic dysregulation was noted in iNPH and IIH, with evidence of impaired CSF dynamics and delayed clearance. SAH studies indicated glymphatic dysfunction with the potential therapeutic effects of nimodipine and tissue plasminogen activator. In stroke, alterations in glymphatic activity correlated with the extent of edema and neurological recovery. TBI studies highlighted the role of the glymphatic system in post-injury cognitive outcomes. Results indicate that the regulation of aquaporin-4 (AQP4) channels is a critical target for therapeutic intervention. The glymphatic system plays a critical role in the pathophysiology of various neurosurgical conditions, influencing brain edema and CSF dynamics. Targeting the regulation of AQP4 channels presents as a significant therapeutic strategy. Although promising, the translation of these findings into clinical practice requires further human studies. Future research should focus on establishing non-invasive biomarkers for glymphatic function and exploring the long-term effects of glymphatic dysfunction.

The Role of Cisternostomy and Cisternal Drainage in the Treatment of Aneurysmal Subarachnoid Hemorrhage: A Comprehensive Review

Aneurysmal subarachnoid hemorrhage (aSAH) provokes a cascade reaction that is responsible for early and delayed brain injuries mediated by intracranial hypertension, hydrocephalus, cerebral vasospasm (CV), and delayed cerebral ischemia (DCI), which result in increased morbidity and mortality. During open microsurgical repair, cisternal access is achieved essentially to gain proximal vascular control and aneurysm exposition. Cisternostomy also allows brain relaxation, removal of cisternal clots, and restoration of the CSF dynamics through the communication between the anterior and posterior circulation cisterns and the ventricular system, with the opening of the Membrane of Liliequist and lamina terminalis, respectively. Continuous postoperative CSF drainage through a cisternal drain (CD) is a valuable option for treating acute hydrocephalus and intracranial hypertension. Moreover, it efficiently removes the blood and toxic degradation products, with a potential benefit on CV, DCI, and shunt-dependent hydrocephalus. Finally, the CD is an effective pathway to administer vasoactive, fibrinolytic, and anti-oxidant agents and shows promising results in decreasing CV and DCI rates while minimizing systemic effects. We performed a comprehensive review to establish the adjuvant role of cisternostomy and CD performed in cases of direct surgical repair for ruptured intracranial aneurysms and their role in the prevention and treatment of aSAH complications.

The glymphatic system's role in traumatic brain injury-related neurodegeneration

In at least some individuals who suffer a traumatic brain injury (TBI), there exists a risk of future neurodegenerative illness. This review focuses on the association between the brain-based paravascular drainage pathway known as the "glymphatic system" and TBI-related neurodegeneration. The glymphatic system is composed of cerebrospinal fluid (CSF) flowing into the brain parenchyma along paravascular spaces surrounding penetrating arterioles where it mixes with interstitial fluid (ISF) before being cleared along paravenous drainage pathways. Aquaporin-4 (AQP4) water channels on astrocytic end-feet appear essential for the functioning of this system. The current literature linking glymphatic system disruption and TBI-related neurodegeneration is largely based on murine models with existing human research focused on the need for biomarkers of glymphatic system function (e.g., neuroimaging modalities). Key findings from the existing literature include evidence of glymphatic system flow disruption following TBI, mechanisms of this decreased flow (i.e., AQP4 depolarization), and evidence of protein accumulation and deposition (e.g., amyloid β, tau). The same studies suggest that glymphatic dysfunction leads to subsequent neurodegeneration, cognitive decline, and/or behavioral change although replication in humans is needed. Identified emerging topics from the literature are as follows: link between TBI, sleep, and glymphatic system dysfunction; influence of glymphatic system disruption on TBI biomarkers; and development of novel treatments for glymphatic system disruption following TBI. Although a burgeoning field, more research is needed to elucidate the role of glymphatic system disruption in TBI-related neurodegeneration.

Traumatic Brain Injuries: Comprehensive Management of Complex Clinical Scenarios

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Outcomes and Predictors of Outcome with Cisternostomy in the Management of Traumatic Brain Injury—A Prospective Observational Study at Tertiary Centre

Background Traumatic brain injury (TBI) is a major cause of morbidity and mortality in young individuals. Goal of management in TBI patients is mainly focused on the secondary injury. Since the cisterns and the brain communicate, it would be possible to decrease the pressure in both these compartments by opening the cisterns to the atmospheric pressure.

Objective To study the outcomes and predictors of outcome with cisternostomy in the management of TBI.

Methods A single tertiary care center's prospective observational study of outcomes with cisternostomy with intraoperative intracranial pressure (ICP) monitoring. Patients were evaluated clinically and radiologically with Marshall CT score. They were categorized into mild, moderate, and severe head injury groups based on Glasgow coma scale (GCS) score. Outcomes were evaluated with Glasgow outcome scale (GOS) score.

Results A total of 25 patients with TBI were enrolled in this study. They underwent cisternostomy with intraoperative ICP monitoring. They were categorized into 4 groups based on the age. In our study, mortality rate was 32%. As much as 48% had good recovery at 3 months follow-up with GOS 4 and 5. Mean ICP after cisternostomy was 6.36 ± 1.91 mm Hg. In our study, there was decrease in ICP after cisternostomy.

Conclusion Age, time interval from trauma to surgery, and ICP showed prognostic importance on outcomes. Cisternostomy can efficiently decrease the ICP in the TBI patients and reduce postoperative complications.

Basal Cisternostomy in Head Injury: More Questions than Answers

Background

Cisternostomy has recently been reintroduced in the setting of severe TBI as an adjuvant surgical technique for decreasing brain edema and refractory intracranial hypertension. However, there is not much clarity regarding its role in head injury.

Objective

Study the effect of cisternostomy on intracranial pressure, morbidity, and mortality in head-injured patients.

Material and Methods

We conducted a single-center quasi-experimental study between November 2018 and November 2020. All candidates for decompressive hemicraniectomy (DHC) were divided into two groups: DHC-BC (undergoing basal cisternostomy with DHC) and DHC (undergoing DHC alone). We compared the impact of surgery on decreasing ICP and clinical outcomes in both groups.

Results

During the study duration, we admitted 659 head-injury patients. Forty patients were included in the study (9 in the DHC-BC group and 31 in the DHC group). Both the groups were comparable in terms of baseline clinical characteristics such as age, gender, preoperative GCS, head injury severity, radiological features, and opening ICP. Patients in both groups had a decline in ICP following surgery. The mean closing pressure in the DHC-BC group (11.3 ± 5.9) was significantly higher than that in the DHC group (5.3 ± 3.5) (P = 0.003). The mean drop in ICP in the DHC-BC group was 14.4 ± 11.5 while that in the DHC group was 18.9 ± 12.4 (P = 0.359). The average total number of hours of ICP >20 mm Hg and intracranial hypertension index were higher for the DHC-BC group. The average number of days of stay in the ICU and hospital were lower for the DHC-BC group (7.0 ± 6.1 and 15.0 ± 20.2, respectively) compared to the DHC group (10.6 ± 9.3 and 19.3 ± 13.9, respectively). The 30-day mortality rate was higher for the DHC-BC group (66.6%) than the DHC group (32.2%). The mean GCS at discharge was better in the DHC-BC group (11.7 ± 2.9) compared to 10.5 ± 3.7 in the DHC group, while 11.1% of patients in the DHC-BC group had a favorable outcome (1-month GOS-E) compared to 9.7% patients in the DHC group.

Conclusions

Our preliminary single-center study failed to show a clear benefit of adding basal cisternostomy to decompressive hemicraniectomy in patients with head injuries.