Posterior fossa ischemic infarction: single-center retrospective review of non-surgical and surgical cases.

Cerebellar ischemic stroke (CIS) is a morbid neurological event, with potentially fatal consequences. There is currently no objective standard of care regarding when surgical procedures are required for this entity. We retrospectively reviewed 763 patients with CIS, 247 patients of which had a stroke larger than 1 cm in greatest dimension on cranial imaging. In this subgroup, 11% of patients received ventriculostomy, 12% suboccipital craniectomy, and 9% mechanical endovascular thrombectomy. Various clinical and radiographic variables were examined for relationship to surgical procedures, 30-day mortality rate, and modified Rankin scores. The smallest volume of stroke requiring a surgical procedure was 15.5 mL3 (BrainLab Software). Patients receiving surgical procedures had a higher incidence of multi-territory infarctions, hydrocephalus, cistern compression, 4th ventricular compression, as well as younger age, lower admission GCS, higher admission NIHSS, and higher 30-day mortality/disability. Patients deemed to require surgical procedures for CIS have a higher expected morbidity and mortality than those not requiring surgery. Various clinical and radiographic variables, including stroke volume, can be used to guide selection of patients requiring surgery.

High-resistance proximal "scaled" ventricular catheters.

PURPOSE: Prove the concept of high-resistance proximal catheters for valve-independent treatment of hydrocephalus. METHODS: A preliminary design process yielded optimal high-resistance proximal ventricular catheters with a "scaled" design and parallel-oriented, U-shaped inlets. Prototypes were manually constructed using carving tools to stamp through silicone tubings. A testing apparatus was developed to simulate cerebrospinal fluid flow through a catheter, and the prototypes were tested against a control catheter for exhibition of an "on/off" phenomenon whereby no flow occurs at low pressures, and flow begins beyond a pressure threshold. Flow distribution was visualized with India ink. Regression analysis was performed to determine linearity. RESULTS: The new designs showed varying amounts of improved flow control with the "scaled" design showing the most practical flow rate control across various pressures, compared to the standard catheter; however, no true "on/off" phenomenon was observed. The "scaled" design showed various degrees of dynamism; its flow rate can be time dependent, and certain maneuvers such as flushing and bending increased flow rate temporarily. Variation in the number of inlets within each "scaled" prototype also affected flow rate. Contrastingly, the flow rate of standard catheters was found to be independent of the number of inlet holes. Ink flow showed even flow distribution in "scaled" prototypes. CONCLUSIONS: This initial feasibility study showed that high-resistance ventricular catheters can be designed to mimic the current/valved system. The "scaled" design demonstrated the best flow control, and its unique features were characterized.

Simulation of proximal catheter occlusion and design of a shunt tap aspiration system.

PURPOSE: Total and partial proximal catheter occlusions are well-known complications of ventriculoperitoneal shunts (VPS). When this occurs, surgeons often attempt to perform a shunt tap. However, the degree of obstruction in a proximal catheter that ultimately leads to shunt malfunction is unknown. METHODS: We developed a benchtop model to simulate proximal catheter occlusion with two hydrostatic reservoirs connected by a VPS catheter system. The Centurion compass device was used to measure pressure across the valve digitally. Wires of varying diameters (equalling different occlusion percentages) were inserted into the catheter's proximal end to stimulate obstruction. A mock shunt tap aspiration was then performed by incorporating a pressure transducer. RESULTS: As a general trend, pressure reading on the device decreases as occlusion increases. At higher levels of occlusion (> 45%), the blockage begins to significantly impede the flow through the catheter, and the pressure drops at a faster rate compared with lower occlusion percentages. The pressure reading converges quickly to 0 with increasing blockage after about 70%. The Centurion compass is able to detect large changes in pressure as evidenced by the major differences in pressure readings between no occlusion, 45%, and 84%. The shunt will not function at 84%. In order to determine the threshold for occlusion beyond which fluid cannot be withdrawn, we tested five levels of occlusion (0%, 33%, 63%, 84%, and 100%) at various aspiration pressures and determined that fluid can still be produced with 0-84% occlusion, but no fluid could be produced at 100% occlusion. CONCLUSIONS: We developed a model of proximal shunt obstruction and found that cerebrospinal fluid (CSF) flow through a VPS is unaffected up to 33% occlusion, begins to become impaired at 45% occlusion, and is miniscule at 84% occlusion. Shunt aspiration was not possible at 84% occlusion. Pressure measured at the reservoir is accurate and correlates with intracranial pressure (ICP) up to approximately 60% proximal occlusion. With partial occlusion up to 70%, ventricular pressure will dictate shunt function.

Cerebral Autoregulation-Guided Optimal Blood Pressure in Sepsis-Associated Encephalopathy: A Case Series.

BACKGROUND: Impaired cerebral autoregulation and cerebral hypoperfusion may play a critical role in the high morbidity and mortality in patients with sepsis-associated encephalopathy (SAE). Bedside assessment of cerebral autoregulation may help individualize hemodynamic targets that optimize brain perfusion. We hypothesize that near-infrared spectroscopy (NIRS)-derived cerebral oximetry can identify blood pressure ranges that enhance autoregulation in patients with SAE and that disturbances in autoregulation are associated with severity of encephalopathy. METHODS: Adult patients with acute encephalopathy directly attributable to sepsis were followed using NIRS-based multimodal monitoring for 12 consecutive hours. We used the correlation in time between regional cerebral oxygen saturation and mean arterial pressure (MAP) to determine the cerebral oximetry index (COx) as a measure of cerebral autoregulation. Autoregulation curves were constructed for each patient with averaged COx values sorted by MAP in 3 sequential 4-hour periods; the optimal pressure (MAPOPT), defined as the MAP associated with most robust autoregulation (lowest COx), was identified in each period. Severity of encephalopathy was measured with Glasgow coma scale (GCS). RESULTS: Six patients with extracranial sepsis met the stringent criteria specified, including no pharmacological sedation or neurologic premorbidity. Optimal MAP was identified in all patients and ranged from 55 to 115 mmHg. Additionally, MAPOPT varied within individual patients over time during monitoring. Disturbed autoregulation, based on COx, was associated with worse neurologic status (GCS < 13) both with and without controlling for age and severity of sepsis (adjusted odds ratio [OR]: 2.11; 95% confidence interval [CI]: 1.77-2.52; P < .001; OR: 2.97; 95% CI: 1.63-5.43; P < .001). CONCLUSIONS: In this high-fidelity group of patients with SAE, continuous, NIRS-based monitoring can identify blood pressure ranges that improve autoregulation. This is important given the association between cerebral autoregulatory function and severity of encephalopathy. Individualizing blood pressure goals using bedside autoregulation monitoring may better preserve cerebral perfusion in SAE than current practice.

Effects of SARS-CoV-2 vaccination on the severity of COVID-19 infection in patients on chronic dialysis.

BACKGROUND: COVID-19 is associated with increased morbidity and mortality in patients with end-stage kidney disease on dialysis. Efficacy of SARS-CoV-2 vaccination to prevent severe COVID-19 disease in end-stage kidney disease patients remains limited. We compared the incidence of COVID-19-related hospitalization and death in dialysis patients based on SARS-CoV-2 vaccine status. METHODS: Retrospective study of adults on chronic dialysis within Mayo Clinic Dialysis System in the Midwest (USA) between April 1st, 2020 and October 31st, 2022, who had a laboratory test positive for SARS-CoV-2 by PCR. Incidence of both COVID-19-related hospitalization and death were compared between vaccinated and unvaccinated patients. RESULTS: SARS-CoV-2 infection was identified in 309 patients, including 183 vaccinated and 126 unvaccinated. The incidence of death (11.1% vs 3.8%, p = 0.02) and hospitalization (55.6% vs 23.5%, p < 0.001) was significantly higher in unvaccinated compared to vaccinated patients. Age at infection, sex, Charlson comorbidity index, dialysis modality, and hospital stays did not differ between the two groups. The incidence of hospitalization was significantly higher in partially vaccinated (63.6% vs 20.9%, p = 0.004) and unboosted (32% vs 16.4%, p = 0.04) patients compared to fully vaccinated and boosted, respectively. Among the 21 patients who died in the whole cohort, 47.6% (n = 10) died during the pre-vaccine period. The composite risk of death or hospitalization was lower among vaccinated patients after adjusting for age, sex and Charlson comorbidity index (OR 0.24, 95% CI 0.15-0.40). CONCLUSIONS: This study supports the use of SARS-CoV-2 vaccination to improve COVID-19 outcomes in patients on chronic dialysis.

Neuropathologic changes associated with stereoelectroencephalography depth electrode placement.

BACKGROUND: The aim of this study was to detail the neuropathologic changes resulting from the surgical placement of stereoelectroencephalography (SEEG) leads in an initial small group of epilepsy cases and to raise awareness of this iatrogenic pathology, especially to those medical providers who specialize in the care of epilepsy patients. METHODS: Five consecutive patients who underwent epilepsy resection surgery following SEEG monitoring at OSF Saint Francis Medical Center were included in our report. Resection specimens were examined grossly and entirely submitted for microscopic evaluation by a neuropathologist. Seizure-related pathologies, as well as histologic changes related to SEEG electrode placement, were documented. RESULTS: The patient cohort included two females and three males, with an age range of 9 to 47 years. Neuropathologic examination revealed one or more seizure-related pathologies in each patient's resection specimen. In addition, all brain resection specimens showed multiple microinfarcts, which appeared to correlate with the placement and size of SEEG electrodes. Patchy leptomeningeal chronic inflammation was also seen in most cases. CONCLUSIONS: SEEG electrode placement is an effective procedure for determining epileptogenic regions and guiding subsequent resection surgeries in medically refractory epilepsy. Multiple microinfarcts and chronic inflammation are commonly seen in brain resection specimens following SEEG electrode insertion, but studies detailing these iatrogenic histopathologic changes are lacking. The clinical significance and long-term implications of multiple small foci of electrode-induced injury that remain in the patient's brain after resection of the epileptogenic focus are unknown and may provide a welcome area for future study.

Temporary Posterior C1-C2 Instrumentation without Fusion for Treatment of Displaced Atlantoaxial Fractures.

OBJECTIVE: To describe open reduction internal fixation (ORIF) with posterior C1-C2 instrumentation without fusion to treat displaced atlantoaxial fractures with later instrumentation removal. METHODS: A retrospective review identified 14 patients (mean age 44 years) with displaced atlantoaxial fractures treated with ORIF without fusion. Patient demographics, fracture morphology, trauma etiology, instrumentation levels, timing of hardware removal, and complications were collected. Patients were maintained in a cervical collar, and healing was confirmed via imaging before instrumentation removal. RESULTS: Fractures included type III odontoid, C2 pars, C1 ring, and complex C1 or C2 fractures. All cases used C1 lateral mass screws and C2 pars or pedicle screws with a C1 cross-link. Two patients had C3 lateral mass screws. All patients showed fracture healing on imaging within 4 months after ORIF. Instrumentation removal was performed in 13 patients. No complications were noted. CONCLUSIONS: Displaced atlantoaxial fractures have been traditionally managed with halo-vest immobilization closed reduction or ORIF with fusion. ORIF without fusion and subsequent hardware removal is an alternative approach. This strategy preserves mobility at C1-C2, avoids halo-vest immobilization, and appears to be a safe option for treatment of atlantoaxial fractures.

Therapeutic efficacy of matrix metalloproteinase-12 suppression on neurological recovery after ischemic stroke: Optimal treatment timing and duration.

We recently showed that the post-ischemic induction of matrix metalloproteinase-12 (MMP-12) in the brain degrades tight junction proteins, increases MMP-9 and TNFα expression, and contributes to the blood-brain barrier (BBB) disruption, apoptosis, demyelination, and infarct volume development. The objectives of this study were to (1) determine the effect of MMP-12 suppression by shRNA-mediated gene silencing on neurological/functional recovery, (2) establish the optimal timing of MMP-12shRNA treatment that provides maximum therapeutic benefit, (3) compare the effectiveness of acute versus chronic MMP-12 suppression, and (4) evaluate potential sex-related differences in treatment outcomes. Young male and female Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion and reperfusion. Cohorts of rats were administered either MMP-12shRNA or scrambled shRNA sequence (control) expressing plasmids (1 mg/kg; i.v.) formulated as nanoparticles. At designated time points after reperfusion, rats from various groups were subjected to a battery of neurological tests to assess their reflex, balance, sensory, and motor functions. Suppression of MMP-12 promoted the neurological recovery of stroke-induced male and female rats, although the effect was less apparent in females. Immediate treatment after reperfusion resulted in a better recovery of sensory and motor function than delayed treatments. Chronic MMP-12 suppression neither enhanced nor diminished the therapeutic effects of acute MMP-12 suppression, indicating that a single dose of plasmid may be sufficient. We conclude that suppressing MMP-12 after an ischemic stroke is a promising therapeutic strategy for promoting the recovery of neurological function.