Optimal bispectral index exists in healthy patients undergoing general anesthesia: A validation study.

PURPOSE: Continuous cerebrovascular reactivity monitoring in both neurocritical and intra-operative care has gained extensive interest in recent years, as it has documented associations with long-term outcomes (in neurocritical care populations) and cognitive outcomes (in operative cohorts). This has sparked further interest into the exploration and evaluation of methods to achieve an optimal cerebrovascular reactivity measure, where the individual patient is exposed to the lowest insult burden of impaired cerebrovascular reactivity. Recent literature has documented, in neural injury populations, the presence of a potential optimal sedation level in neurocritical care, based on the relationship between cerebrovascular reactivity and quantitative depth of sedation (using bispectral index (BIS)) - termed BISopt. The presence of this measure outside of neural injury patients has yet to be proven. METHODS: We explore the relationship between BIS and continuous cerebrovascular reactivity in two cohorts: (A) healthy population undergoing elective spinal surgery under general anesthesia, and (B) healthy volunteer cohort of awake controls. RESULTS: We demonstrate the presence of BISopt in the general anesthesia population (96% of patients), and its absence in awake controls, providing preliminary validation of its existence outside of neural injury populations. Furthermore, we found BIS to be sufficiently separate from overall systemic blood pressure, this indicates that they impact different pathophysiological phenomena to mediate cerebrovascular reactivity. CONCLUSIONS: Findings here carry implications for the adaptation of the individualized physiologic BISopt concept to non-neural injury populations, both within critical care and the operative theater. However, this work is currently exploratory, and future work is required.

Patient Selection Criteria in Ambulatory Spine Surgery: Single Canadian Provincial Experience.

BACKGROUND: Ambulatory spinal surgery is a care delivery model meant to improve patient outcomes and reduce in-hospital length of stay (LOS). We reviewed the experience of implementing an outpatient spine surgery program in Manitoba, Canada and highlight elements that can be used to reduce LOS and re-presentation to hospital. METHODS: This is a retrospective cohort study using data from the Canadian Spine Outcomes and Research Network and independent chart review of adult patients undergoing outpatient spinal surgery between 2015 and 2018. Patient demographics, comorbidities, perioperative course, LOS, and readmissions were analyzed. RESULTS: We included 217 patients in this analysis. The mean LOS was 36.2 hours; 71.98% of patients had a LOS <24 hours. A Kruskal-Wallis test by ranks analysis was conducted and identified 7 elements that correlated with prolonged length of stay (>1 day): age older than 55 (P = 0.027), body mass index >25 (P = 0.045), uncontrolled diabetes (P = 0.015), preoperative use of opioid medication (P = 0.024), American Society of Anesthesiologists classification of 3 (P = 0.023), non-minimally invasive surgical approach, and multilevel procedures. Most (94.1%) of the patients with none of these elements (i.e., age <55, low body mass index, normal/controlled diabetes, minimal preoperative opioid use, American Society of Anesthesiologist classification <3, minimally invasive surgical procedure) had a favorable LOS, <24 hours, compared with 84.8% with 1 risk factor, 80.4% of those with two, 69.8% with three, 53.1% with four, and 31.2% with 5 or more. A small number of patients (14.98%) presented to an emergency department within 90 days of their operation, and there was a 6.28% readmission rate. CONCLUSIONS: We identified several patient and surgical criteria that correlate with prolonged length of stays following planned ambulatory spine surgery. Our work provides some empiric evidence to help guide surgeons on which patients and approaches are ideal for ambulatory surgery.

The Impact of Mean Arterial Pressure on Functional Outcome Post Trauma-Related Acute Spinal Cord Injury: A Scoping Systematic Review of the Human Literature.

PURPOSE: To perform a scoping systematic review on the literature surrounding mean arterial pressure (MAP) and functional outcomes post traumatic acute spinal cord injury (ASCI). METHODS: We performed a systematic review of the literature via searching MEDLINE, BIOSIS, EMBASE, Global Health, SCOPUS, and Cochrane Library from inception to January 2015. We also performed a handsearch of various published meeting proceedings. Through a 2-step review process, employing 2 independent reviewers, we selected articles for the final review based on predefined inclusion/exclusion criteria. RESULTS: Nine studies were included in the final review. Only 2 were prospective studies. All studies documented some degree of objective functional outcome in relation to MAP posttraumatic ASCI. Four studies documented a relation between higher MAP and improved functional outcome. Five studies failed to show any relationship between MAP and functional outcome. CONCLUSIONS: Although no definitive conclusions could be reached based on the data collected, this study does give valuable insight into future avenues of research on the topic of hemodynamic management in traumatic ASCI as well as provides guidelines for refinement of future study design.

Extensive Mirror-Image Neurofibromas of Entire Spine Resulting in Spastic Tetraplegia.

Neurofibromatosis 1 (NF1) is associated with increased incidence of spinal tumors including neurofibromas. The majority of NF1-associated spine neurofibromas are asymptomatic; however, a minority of patients will experience neurologic symptoms that can range from mild paresthesia, radiculopathy, myelopathy, and focal weakness to quadriplegia in extreme cases. We present a 21-year-old male diagnosed with NF1 in infancy and followed for multiple mirror-image neurofibromas involving the entire spine. He was asymptomatic until age 14 when he developed neck pain and progressive tetraplegia with magnetic resonance imaging showing severe cord compression secondary to bilateral C2 neurofibromas. Emergent cervical decompression was performed at C1-C3 along with debulking of bilateral neurofibromas. Postoperatively he regained full strength with no signs of myelopathy several years postoperatively. This case demonstrates a dramatic neuroimaging finding and emphasizes the potential for significant neurologic deterioration in previously asymptomatic NF1 patients, highlighting the need for long-term follow-up.

The Impact of Mean Arterial Pressure on Functional Outcome Post-Acute Spinal Cord Injury: A Scoping Systematic Review of Animal Models.

The aim of this work was to perform a scoping systematic review on the animal literature surrounding mean arterial blood pressure (MAP) and functional outcomes post-acute spinal cord injury (ASCI). We performed a systematic review of the literature by searching: MEDLINE, BIOSIS, EMBASE, Global Health, SCOPUS, and Cochrane Library from inception to January 2015. We also performed a hand search of various published meeting proceedings. Through a two-step review process, using two independent reviewers, we selected articles for the final review based on pre-defined inclusion/exclusion criteria. Ten studies were included within the final systematic review. A variety of animal models were used within these studies. All included studies had some objective means of documenting functional outcome post-manipulation of the MAP. Four studies could be considered to be "positive studies," showing some neurological improvement or beneficial effect to having the blood pressure manipulated. Two studies displayed worse functional outcomes secondary to episodes of hypotension. Four studies failed to demonstrate a relationship between MAP and functional outcome within the animal models. This review concludes that, within the animal literature, there is insufficient evidence to draw a conclusion about the effect of MAP on neurological outcome in animal models of ASCI.

Default mode network functional connectivity altered in failed back surgery syndrome.

UNLABELLED: The purpose of this study was to identify alterations in the default mode network of failed back surgery syndrome patients as compared to healthy subjects. Resting state functional magnetic resonance imaging was conducted at 3 Tesla and data were analyzed with an independent component analysis. Results indicate an overall reduced functional connectivity of the default mode network and recruitment of additional pain modulation brain regions, including dorsolateral prefrontal cortex, insula, and additional sensory motor integration brain regions, including precentral and postcentral gyri, for failed back surgery syndrome patients. PERSPECTIVE: This article presents alterations in the default mode network of chronic low back pain patients with failed back surgery syndrome as compared to healthy participants.

Relationship between ambulatory performance and self-rated disability in patients with lumbar spinal stenosis.

STUDY DESIGN: A cross-sectional study. OBJECTIVE: To identify the relationship between performance measures derived from accelerometry and subjective reports of pain, disability, and health in patients with lumbar spinal stenosis (LSS). SUMMARY OF BACKGROUND DATA: Accelerometers have emerged as a measure of performance, providing the ability to characterize the pattern and magnitude of real-life activity, and sedentarism. Pain and loss of function, particularly ambulation, are common in LSS. The extent to which pain, perceived disability, and self-rated health relate to performance in patients with LSS is not well known. METHODS: Data regarding self-reported pain, disability (Oswestry Disability Index, Roland-Morris Disability Questionnaire, and Disabilities of the Arm, Shoulder, and Hand), and health (36-Item Short Form Health Survey [SF-36]) were collected from patients with LSS (n = 33). Physical activity, ambulation, and inactivity performance measures were derived from 7-day accelerometer records. Correlation and stepwise regression were used. RESULTS: The physical function subscale of the SF-36, a non-pathology-specific outcome, had the best overall correlation to physical activity and ambulation (average r = 0.53) compared with pain (average r = 0.32) and disability (average r = -0.45) outcomes. Stepwise regression models for performance were predominantly single-variable models (4 of 8 models); pain was not selected as a predictor. A second non-pathology-specific outcome, the Disabilities of Arm Shoulder and Hand, improved the prediction of performance in 5 of 8 models. CONCLUSION: Subjective measures of pain and disability had limited ability to account for real-life performance in patients with LSS. Future research is required to identify determinants of performance in patients with LSS because barriers to activity may not be disease-specific.