Return of intracranial beta oscillations and traveling waves with recovery from traumatic brain injury.

Traumatic brain injury (TBI) remains a pervasive clinical problem associated with significant morbidity and mortality. However, TBI remains clinically and biophysically ill-defined, and prognosis remains difficult even with the standardization of clinical guidelines and advent of multimodality monitoring. Here we leverage a unique data set from TBI patients implanted with either intracranial strip electrodes during craniotomy or quad-lumen intracranial bolts with depth electrodes as part of routine clinical practice. By extracting spectral profiles of this data, we found that the presence of narrow-band oscillatory activity in the beta band (12-30 Hz) closely corresponds with the neurological exam as quantified with the standard Glasgow Coma Scale (GCS). Further, beta oscillations were distributed over the cortical surface as traveling waves, and the evolution of these waves corresponded to recovery from coma, consistent with the putative role of waves in perception and cognitive activity. We consequently propose that beta oscillations and traveling waves are potential biomarkers of recovery from TBI. In a broader sense, our findings suggest that emergence from coma results from recovery of thalamo-cortical interactions that coordinate cortical beta rhythms.

Validation of the International Classification of Diseases, Tenth Revision-Clinical Modification Diagnostic Code for Essential Tremor.

Background: The positive predictive value (PPV) of the International Classification of Diseases, Ninth Revision-Clinical Modification (ICD-9-CM) code for "essential and other specified forms of tremor" in identifying essential tremor (ET) cases was found to be less than 50%. The ability of the ICD-10-CM G25.0 code for "essential tremor" to identify ET has not been determined. The study objective was to determine the PPV of the G25.0 code. Methods: Patients in a tertiary health system with a primary care encounter associated with ICD-10-CM code G25.0 in 2022 underwent medical record review to determine if the consensus criteria from the International Parkinson and Movement Disorder Society for an ET diagnosis were met. Results: 442 patients were included. The PPV of G25.0 in identifying probable ET cases was 74.7% (95% confidence interval (CI) 70.4-78.5%). Among patients prescribed propranolol, the PPV improved to 87.8% (95% CI 78.0-93.6%). Discussion: Compared to the ICD-9-CM code 333.1, G25.0 is superior for identifying ET cases. A potential limitation of this study is that the consensus criteria applied relies on nonspecific physical exam findings which may lead to an overestimation of the PPV of G25.0. Highlights: The ICD-10-CM diagnosis code for essential tremor has not been previously validated. The objective of this study was to determine the PPV of the G25.0 code. The PPV in identifying essential tremor cases was 74.7%. The PPV improved among patients prescribed propranolol.

A surgical decision aid for occipital neuralgia with literature review and single center case series.

BACKGROUND: Occipital neuralgia (ON) is a debilitating headache disorder. Due to the rarity of this disorder and lack of high-level evidence, a clear framework for choosing the optimal surgical approach for medically refractory ON incorporating shared decision making with patients does not exist. METHODS: A literature review of studies reporting pain outcomes of patients who underwent surgical treatment for ON was performed, as well as a retrospective chart review of patients who underwent surgery for ON within our institution. RESULTS: Thirty-two articles met the inclusion criteria. A majority of the articles were retrospective case series (22/32). The mean number of patients across the studies was 34 (standard deviation (SD) 39). Among the 13 studies that reported change in pain score on 10-point scales, a study of 20 patients who had undergone C2 and/or C3 ganglionectomies reported the greatest reduction in pain intensity after surgery. The studies evaluating percutaneous ablative methods including radiofrequency ablation and cryoablation showed the smallest reduction in pain scores overall. At our institution from 2014 to 2023, 11 patients received surgical treatment for ON with a mean follow-up of 187 days (SD 426). CONCLUSION: Based on these results, the first decision aid for selecting a surgical approach to medically refractory ON is presented. The algorithm prioritizes nerve sparing followed by non-nerve sparing techniques with the incorporation of patient preference. Shared decision making is critical in the treatment of ON given the lack of clear scientific evidence regarding the superiority of a particular surgical method.

Subsensory stochastic electrical stimulation targeting muscle afferents alters gait control during locomotor adaptations to haptic perturbations.

Subsensory noise stimulation targeting sensory receptors has been shown to improve balance control in healthy and impaired individuals. However, the potential for application of this technique in other contexts is still unknown. Gait control and adaptation rely heavily on the input from proprioceptive organs in the muscles and joints. Here we investigated the use of subsensory noise stimulation as a means to influence motor control by altering proprioception during locomotor adaptations to forces delivered by a robot. The forces increase step length unilaterally and trigger an adaptive response that restores the original symmetry. Healthy participants performed two adaptation experiments, one with stimulation applied to the hamstring muscles and one without. We found that participants adapted faster but to a lesser extent when undergoing stimulation. We argue that this behavior is because of the dual effect that the stimulation has on the afferents encoding position and velocity in the muscle spindles.

Long-term outcomes of mesial temporal laser interstitial thermal therapy for drug-resistant epilepsy and subsequent surgery for seizure recurrence: a multi-centre cohort study.

BACKGROUND: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive alternative to surgical resection for drug-resistant mesial temporal lobe epilepsy (mTLE). Reported rates of seizure freedom are variable and long-term durability is largely unproven. Anterior temporal lobectomy (ATL) remains an option for patients with MRgLITT treatment failure. However, the safety and efficacy of this staged strategy is unknown. METHODS: This multicentre, retrospective cohort study included 268 patients consecutively treated with mesial temporal MRgLITT at 11 centres between 2012 and 2018. Seizure outcomes and complications of MRgLITT and any subsequent surgery are reported. Predictive value of preoperative variables for seizure outcome was assessed. RESULTS: Engel I seizure freedom was achieved in 55.8% (149/267) at 1 year, 52.5% (126/240) at 2 years and 49.3% (132/268) at the last follow-up ≥1 year (median 47 months). Engel I or II outcomes were achieved in 74.2% (198/267) at 1 year, 75.0% (180/240) at 2 years and 66.0% (177/268) at the last follow-up. Preoperative focal to bilateral tonic-clonic seizures were independently associated with seizure recurrence. Among patients with seizure recurrence, 14/21 (66.7%) became seizure-free after subsequent ATL and 5/10 (50%) after repeat MRgLITT at last follow-up≥1 year. CONCLUSIONS: MRgLITT is a viable treatment with durable outcomes for patients with drug-resistant mTLE evaluated at a comprehensive epilepsy centre. Although seizure freedom rates were lower than reported with ATL, this series represents the early experience of each centre and a heterogeneous cohort. ATL remains a safe and effective treatment for well-selected patients who fail MRgLITT.

Cerebellar deep brain stimulation for the treatment of movement disorders in cerebral palsy.

OBJECTIVE: Cerebral palsy (CP) represents the most common childhood physical disability that encompasses disorders of movement and posture attributed to nonprogressive disturbances that occurred in the developmental fetal or infant brain. Dyskinetic CP (DCP), the second most common type of CP after spastic forms, refers to a subset of patients in whom dystonia and choreoathetosis are the predominant motor manifestations. Most children with CP have abnormal brain MRI studies indicative of cortical and deep gray matter damage consistent with hypoxic ischemic encephalopathy, which may preclude or suggest decreased efficacy of standard deep brain stimulation (DBS) targets. The cerebellum has been posited as an attractive target for treatment of DCP because it is frequently spared from hypoxic ischemic damage and has shown promise in alleviating patient symptoms both in early work in the 1970s and in more recent case series with DBS. METHODS: The authors performed bilateral cerebellar DBS implantation, targeting the dentate nucleus (DN) and cerebellar outflow pathway, in 3 patients with DCP. Leads were connected to a pulse generator that senses local field potentials during chronic continuous DBS. The authors report their surgical methods, examples of chronic cerebellar local field potential recordings, and preliminary clinical outcomes. Motor outcomes were assessed using the Burke-Fahn-Marsden Dystonia Rating Scale. RESULTS: Three patients 14-22 years old with DCP and MRI evidence of structural damage to the basal ganglia were offered cerebellar stimulation targeting the DN. All patients tolerated the procedure well and demonstrated improvement in subjective motor function as well as objective improvement in the Burke-Fahn-Marsden Dystonia Rating Scale movement subscale, although the range of responses was variable (19%-40%). Patients experienced subjective improvement in motor function including ease of hand movements and coordination, gait, head control, speech, decreased overflow, and diminished muscle tightness. CONCLUSIONS: DBS of the dentate nuclei in patients with DCP appears to be safe and shows preliminary evidence of clinical benefit. New chronic sensing technology may allow for determination of in vivo mechanisms of network disruption in DCP and allow for further understanding of the effects of neuromodulation on brain physiology. Larger studies with long-term follow up will be required to further elucidate the clinical benefits of this therapy. This report addresses a gap in the literature regarding the technical approach to image-based stereotactic targeting and chronic neural recording in the DN.

Modern intracranial electroencephalography for epilepsy localization with combined subdural grid and depth electrodes with low and improved hemorrhagic complication rates.

OBJECTIVE: Recent trends have moved from subdural grid electrocorticography (ECoG) recordings toward stereo-electroencephalography (SEEG) depth electrodes for intracranial localization of seizures, in part because of perceived morbidity from subdural grid and strip electrodes. For invasive epilepsy monitoring, the authors describe the outcomes of a hybrid approach, whereby patients receive a combination of subdural grids, strips, and frameless stereotactic depth electrode implantations through a craniotomy. Evolution of surgical techniques was employed to reduce complications. In this study, the authors review the surgical hemorrhage and functional outcomes of this hybrid approach. METHODS: A retrospective review was performed of consecutive patients who underwent hybrid implantation from July 2012 to May 2022 at an academic epilepsy center by a single surgeon. Outcomes included hemorrhagic and nonhemorrhagic complications, neurological deficits, length of monitoring, and number of electrodes. RESULTS: A total of 137 consecutive procedures were performed; 113 procedures included both subdural and depth electrodes. The number of depth electrodes and electrode contacts did not increase the risk of hemorrhage. A mean of 1.9 ± 0.8 grid, 4.9 ± 2.1 strip, and 3.0 ± 1.9 depth electrodes were implanted, for a mean of 125.1 ± 32 electrode contacts per patient. The overall incidence of hematomas over the study period was 5.1% (7 patients) and decreased significantly with experience and the introduction of new surgical techniques. The incidence of hematomas in the last 4 years of the study period was 0% (55 patients). Symptomatic hematomas were all delayed and extra-axial. These patients required surgical evacuation, and there were no cases of hematoma recurrence. All neurological deficits related to hematomas were temporary and were resolved at hospital discharge. There were 2 nonhemorrhagic complications. The mean duration of monitoring was 7.3 ± 3.2 days. Seizures were localized in 95% of patients, with 77% of patients eventually undergoing resection and 17% undergoing responsive neurostimulation device implantation. CONCLUSIONS: In the authors' institutional experience, craniotomy-based subdural and depth electrode implantation was associated with low hemorrhage rates and no permanent morbidity. The rate of hemorrhage can be nearly eliminated with surgical experience and specific techniques. The decision to use subdural electrodes or SEEG should be tailored to the patient's unique pathology and surgeon experience.

Source-sink connectivity: a novel interictal EEG marker for seizure localization.

Over 15 million epilepsy patients worldwide have drug-resistant epilepsy. Successful surgery is a standard of care treatment but can only be achieved through complete resection or disconnection of the epileptogenic zone, the brain region(s) where seizures originate. Surgical success rates vary between 20% and 80%, because no clinically validated biological markers of the epileptogenic zone exist. Localizing the epileptogenic zone is a costly and time-consuming process, which often requires days to weeks of intracranial EEG (iEEG) monitoring. Clinicians visually inspect iEEG data to identify abnormal activity on individual channels occurring immediately before seizures or spikes that occur interictally (i.e. between seizures). In the end, the clinical standard mainly relies on a small proportion of the iEEG data captured to assist in epileptogenic zone localization (minutes of seizure data versus days of recordings), missing opportunities to leverage these largely ignored interictal data to better diagnose and treat patients. IEEG offers a unique opportunity to observe epileptic cortical network dynamics but waiting for seizures increases patient risks associated with invasive monitoring. In this study, we aimed to leverage interictal iEEG data by developing a new network-based interictal iEEG marker of the epileptogenic zone. We hypothesized that when a patient is not clinically seizing, it is because the epileptogenic zone is inhibited by other regions. We developed an algorithm that identifies two groups of nodes from the interictal iEEG network: those that are continuously inhibiting a set of neighbouring nodes ('sources') and the inhibited nodes themselves ('sinks'). Specifically, patient-specific dynamical network models were estimated from minutes of iEEG and their connectivity properties revealed top sources and sinks in the network, with each node being quantified by source-sink metrics. We validated the algorithm in a retrospective analysis of 65 patients. The source-sink metrics identified epileptogenic regions with 73% accuracy and clinicians agreed with the algorithm in 93% of seizure-free patients. The algorithm was further validated by using the metrics of the annotated epileptogenic zone to predict surgical outcomes. The source-sink metrics predicted outcomes with an accuracy of 79% compared to an accuracy of 43% for clinicians' predictions (surgical success rate of this dataset). In failed outcomes, we identified brain regions with high metrics that were untreated. When compared with high frequency oscillations, the most commonly proposed interictal iEEG feature for epileptogenic zone localization, source-sink metrics outperformed in predictive power (by a factor of 1.2), suggesting they may be an interictal iEEG fingerprint of the epileptogenic zone.

Social Media Presence Across U.S. Neurosurgical Residency Programs and Subspecialties.

OBJECTIVE: U.S. neurosurgery programs are increasingly using social media accounts. We performed a search and analysis of social media accounts across all U.S. neurosurgical training programs with an attempt at understanding the relative utilization by various subspecialties. METHODS: We compiled a list of all Accreditation Council for Graduate Medical Education-accredited U.S. neurosurgery programs and the faculty. Each faculty member was classified on the basis of their subspecialty. Next, the Twitter, Facebook, and Instagram profiles were extensively searched for the number of followers and posts. RESULTS: We analyzed 110 programs with 1829 clinical faculty. Programs with a larger number of faculty (P = 0.035; χ2 = 13.528) and residents (P = 0.003; χ2 = 11.865) were more likely to have a social media account. Likewise, faculty and resident numbers had a positive correlation to Twitter (P = 0.037 for faculty size; P = 0.008 for residents' size) and Instagram followers (P = 0.003 for faculty size; P < 0.001 for residents' size). We additionally found a significant association between subspecialty type and the presence of a Twitter and Instagram account (P = 0.001; P = 0.028) and the number of followers (P = 0.004; P = 0.013), especially the vascular and oncology subspecialties. CONCLUSIONS: Many U.S. neurosurgical programs have social media accounts with larger programs likely to have social media accounts. While there is a larger percentage of spine faculty within individual departments, vascular and oncology subspecialties are more likely to have a Twitter account. We suggest the need for increased engagement among spine faculty across social media platforms.

Design-development of an at-home modular brain-computer interface (BCI) platform in a case study of cervical spinal cord injury.

OBJECTIVE: The objective of this study was to develop a portable and modular brain-computer interface (BCI) software platform independent of input and output devices. We implemented this platform in a case study of a subject with cervical spinal cord injury (C5 ASIA A). BACKGROUND: BCIs can restore independence for individuals with paralysis by using brain signals to control prosthetics or trigger functional electrical stimulation. Though several studies have successfully implemented this technology in the laboratory and the home, portability, device configuration, and caregiver setup remain challenges that limit deployment to the home environment. Portability is essential for transitioning BCI from the laboratory to the home. METHODS: The BCI platform implementation consisted of an Activa PC + S generator with two subdural four-contact electrodes implanted over the dominant left hand-arm region of the sensorimotor cortex, a minicomputer fixed to the back of the subject's wheelchair, a custom mobile phone application, and a mechanical glove as the end effector. To quantify the performance for this at-home implementation of the BCI, we quantified system setup time at home, chronic (14-month) decoding accuracy, hardware and software profiling, and Bluetooth communication latency between the App and the minicomputer. We created a dataset of motor-imagery labeled signals to train a binary motor imagery classifier on a remote computer for online, at-home use. RESULTS: Average bluetooth data transmission delay between the minicomputer and mobile App was 23 ± 0.014 ms. The average setup time for the subject's caregiver was 5.6 ± 0.83 min. The average times to acquire and decode neural signals and to send those decoded signals to the end-effector were respectively 404.1 ms and 1.02 ms. The 14-month median accuracy of the trained motor imagery classifier was 87.5 ± 4.71% without retraining. CONCLUSIONS: The study presents the feasibility of an at-home BCI system that subjects can seamlessly operate using a friendly mobile user interface, which does not require daily calibration nor the presence of a technical person for at-home setup. The study also describes the portability of the BCI system and the ability to plug-and-play multiple end effectors, providing the end-user the flexibility to choose the end effector to accomplish specific motor tasks for daily needs. Trial registration ClinicalTrials.gov: NCT02564419. First posted on 9/30/2015.

Machine learning to predict passenger mortality and hospital length of stay following motor vehicle collision.

OBJECTIVE: Motor vehicle collisions (MVCs) account for 1.35 million deaths and cost $518 billion US dollars each year worldwide, disproportionately affecting young patients and low-income nations. The ability to successfully anticipate clinical outcomes will help physicians form effective management strategies and counsel families with greater accuracy. The authors aimed to train several classifiers, including a neural network model, to accurately predict MVC outcomes. METHODS: A prospectively maintained database at a single institution's level I trauma center was queried to identify all patients involved in MVCs over a 20-year period, generating a final study sample of 16,287 patients from 1998 to 2017. Patients were categorized by in-hospital mortality (during admission) and length of stay (LOS), if admitted. All models included age (years), Glasgow Coma Scale (GCS) score, and Injury Severity Score (ISS). The in-hospital mortality and hospital LOS models further included time to admission. RESULTS: After comparing a variety of machine learning classifiers, a neural network most effectively predicted the target features. In isolated testing phases, the neural network models returned reliable, highly accurate predictions: the in-hospital mortality model performed with 92% sensitivity, 90% specificity, and a 0.98 area under the receiver operating characteristic curve (AUROC), and the LOS model performed with 2.23 days mean absolute error after optimization. CONCLUSIONS: The neural network models in this study predicted mortality and hospital LOS with high accuracy from the relatively few clinical variables available in real time. Multicenter prospective validation is ultimately required to assess the generalizability of these findings. These next steps are currently in preparation.

Long-term seizure and psychiatric outcomes following laser ablation of mesial temporal structures.

OBJECTIVE: Postsurgical seizure outcome following laser interstitial thermal therapy (LiTT) for the management of drug-resistant mesial temporal lobe epilepsy (MTLE) has been limited to 2 years. Furthermore, its impact on presurgical mood and anxiety disorders has not been investigated. The objectives of this study were (1) to identify seizure outcome changes over a period ranging from 18 to 81 months; (2) to investigate the seizure-free rate in the last follow-up year; (3) to identify the variables associated with seizure freedom; and (4) to identify the impact of LiTT on presurgical mood and anxiety disorders. METHODS: Medical records of all patients who underwent LiTT for MTLE from 2013 to 2019 at the University of Miami Comprehensive Epilepsy Center were retrospectively reviewed. Demographic, epilepsy-related, cognitive, psychiatric, and LiTT-related data were compared between seizure-free (Engel Class I) and non-seizure-free (Engel Class II + III + IV) patients. Statistical analyses included univariate and multivariate stepwise logistic regression analyses. RESULTS: Forty-eight patients (mean age = 43 ± 14.2 years, range = 21-78) were followed for a mean period of 50 ± 20.7 months (range = 18-81); 29 (60.4%) achieved an Engel Class I outcome, whereas 11 (22.9%) had one to three seizures/year. Seizure-freedom rate decreased from 77.8% to 50% among patients with 24- and >61-month follow-up periods, respectively. In the last follow-up year, 83% of all patients were seizure-free. Seizure freedom was associated with having mesial temporal sclerosis (MTS), no presurgical focal to bilateral tonic-clonic seizures, and no psychopathology in the last follow-up year. Presurgical mood and/or anxiety disorder were identified in 30 patients (62.5%) and remitted after LiTT in 19 (62%). SIGNIFICANCE: LiTT appears to be a safe and effective surgical option for treatment-resistant MTLE, particularly among patients with MTS. Remission of presurgical mood and anxiety disorders can also result from LiTT.

A multiparametric pharmacogenomic strategy for drug repositioning predicts therapeutic efficacy for glioblastoma cell lines.

BACKGROUND: Poor prognosis of glioblastoma patients and the extensive heterogeneity of glioblastoma at both the molecular and cellular level necessitates developing novel individualized treatment modalities via genomics-driven approaches. METHODS: This study leverages numerous pharmacogenomic and tissue databases to examine drug repositioning for glioblastoma. RNA-seq of glioblastoma tumor samples from The Cancer Genome Atlas (TCGA, n = 117) were compared to "normal" frontal lobe samples from Genotype-Tissue Expression Portal (GTEX, n = 120) to find differentially expressed genes (DEGs). Using compound gene expression data and drug activity data from the Library of Integrated Network-Based Cellular Signatures (LINCS, n = 66,512 compounds) CCLE (71 glioma cell lines), and Chemical European Molecular Biology Laboratory (ChEMBL) platforms, we employed a summarized reversal gene expression metric (sRGES) to "reverse" the resultant disease signature for GBM and its subtypes. A multiparametric strategy was employed to stratify compounds capable of blood-brain barrier penetrance with a favorable pharmacokinetic profile (CNS-MPO). RESULTS: Significant correlations were identified between sRGES and drug efficacy in GBM cell lines in both ChEMBL(r = 0.37, P < .001) and Cancer Therapeutic Response Portal (CTRP) databases (r = 0.35, P < 0.001). Our multiparametric algorithm identified two classes of drugs with highest sRGES and CNS-MPO: HDAC inhibitors (vorinostat and entinostat) and topoisomerase inhibitors suitable for drug repurposing. CONCLUSIONS: Our studies suggest that reversal of glioblastoma disease signature correlates with drug potency for various GBM subtypes. This multiparametric approach may set the foundation for an early-phase personalized -omics clinical trial for glioblastoma by effectively identifying drugs that are capable of reversing the disease signature and have favorable pharmacokinetic and safety profiles.

Brain-Computer interface control of stepping from invasive electrocorticography upper-limb motor imagery in a patient with quadriplegia.

Introduction: Most spinal cord injuries (SCI) result in lower extremities paralysis, thus diminishing ambulation. Using brain-computer interfaces (BCI), patients may regain leg control using neural signals that actuate assistive devices. Here, we present a case of a subject with cervical SCI with an implanted electrocorticography (ECoG) device and determined whether the system is capable of motor-imagery-initiated walking in an assistive ambulator. Methods: A 24-year-old male subject with cervical SCI (C5 ASIA A) was implanted before the study with an ECoG sensing device over the sensorimotor hand region of the brain. The subject used motor-imagery (MI) to train decoders to classify sensorimotor rhythms. Fifteen sessions of closed-loop trials followed in which the subject ambulated for one hour on a robotic-assisted weight-supported treadmill one to three times per week. We evaluated the stability of the best-performing decoder over time to initiate walking on the treadmill by decoding upper-limb (UL) MI. Results: An online bagged trees classifier performed best with an accuracy of 84.15% averaged across 9 weeks. Decoder accuracy remained stable following throughout closed-loop data collection. Discussion: These results demonstrate that decoding UL MI is a feasible control signal for use in lower-limb motor control. Invasive BCI systems designed for upper-extremity motor control can be extended for controlling systems beyond upper extremity control alone. Importantly, the decoders used were able to use the invasive signal over several weeks to accurately classify MI from the invasive signal. More work is needed to determine the long-term consequence between UL MI and the resulting lower-limb control.

One-donor, two-recipient extracranial-intracranial bypass series for moyamoya and cerebral occlusive disease: rationale, clinical and angiographic outcomes, and intraoperative blood flow analysis.

OBJECTIVE: Cerebral extracranial-intracranial (EC-IC) direct bypass is a commonly used procedure for ischemic vasculopathy. A previously described variation of this technique is to utilize one donor artery to supply two recipient arteries, which the authors designate as 1D2R. The purpose of this study is to present a single surgeon's series of 1D2R direct bypasses for moyamoya and ischemia using detailed clinical, angiographic, and intraoperative blood flow measurement data. To the authors' knowledge, this is the largest series reported to date. METHODS: Hospital, office, and radiographic imaging records for all patients who underwent cerebral revascularization using a 1D2R bypass by the senior author were reviewed. The patients' demographic information, clinical presentation, associated medical conditions, intraoperative information, and postoperative course were obtained from reviewing the medical records. RESULTS: A total of 21 1D2R bypasses were performed in 19 patients during the study period. Immediate bypass patency was 100% and was 90% on delayed follow-up. The mean initial cut flow index (CFI(i)) was 0.64 ± 0.33 prior to the second anastomosis and the mean final value (CFI(f)) was 0.94 ± 0.38 after the second anastomosis (p < 0.001). The overall bypass flow increased on average by 50% (mean 17.9 ml/min, range -10 to 40 ml/min) with the addition of the second anastomosis. There was no significant difference in the overall flow measurements when the end-to-side anastomosis or side-to-side anastomosis was performed first. There was a statistically significant difference in the proportion of patients with a modified Rankin Scale (mRS) score of 0 or 1 postoperatively compared to preoperatively (p < 0.01). Through the application of Poiseuille's law, the authors analyzed flow dynamics, deduced the component vascular resistances based on an analogy to electrical circuits and Ohm's law, and introduced the new concepts of "second anastomosis relative augmentation" and "second anastomosis sink index" in the evaluation of 1D2R bypasses. CONCLUSIONS: The application of the 1D2R technique in a series of 19 consecutive patients undergoing direct EC-IC bypass for flow augmentation demonstrated high patency rates, statistically significantly higher CFIs compared to 1D1R, and improved mRS scores at last clinical follow-up. Additionally, the technique allows a shorter dissection time and preserves blood flow to the scalp. The routine utilization of intraoperative volumetric flow measurements in such surgeries allows a deeper understanding of the hemodynamic impact on individual patients.

Intracranial Hypertension After Primary Decompressive Craniectomy for Head Trauma.

BACKGROUND: Primary decompressive craniectomy (DC) is commonly performed for patients with traumatic brain injury (TBI). Some, but not all patients, will benefit from invasive monitoring of intracranial pressure (ICP) after surgery. We intended to identify risk factors for elevated ICP after primary DC to treat TBI. METHODS: A retrospective chart review study identified all patients at our institution who underwent primary DC for TBI during the study period and who had ICP monitors placed at the time of surgery. Various preoperative and intraoperative variables were assessed for correlation with the presence of postoperative elevated ICP. RESULTS: Postoperative elevated ICP occurred in 36% of patients after DC. In univariate analysis, Glasgow Coma Scale <8, abnormal pupillary examination, and intraoperative brain swelling were all associated with elevated postoperative ICP. However, in multivariate analysis only intraoperative brain swelling was associated with elevated postoperative ICP (incidence 56% vs. 5%, P = 0.0043). CONCLUSIONS: Placement of an ICP monitor at the time of primary DC for patients with TBI should be considered if there is intraoperative brain swelling.