Guy Rosenthal, Rene O. Sanchez-Mejia, Nicolas Phan, J. Claude Hemphill III, Christine Martin and Geoffrey T. Manley
Cerebral autoregulation may be altered after traumatic brain injury (TBI). Recent evidence suggests that patients' autoregulatory status following severe TBI may influence cerebral perfusion pressure management. The authors evaluated the utility of incorporating a recently upgraded parenchymal thermal diffusion probe for the measurement of cerebral blood flow (CBF) in the neurointensive care unit for assessing cerebral autoregulation and vasoreactivity at bedside.
The authors evaluated 20 patients with severe TBI admitted to San Francisco General Hospital who underwent advanced neuromonitoring. Patients had a parenchymal thermal diffusion probe placed for continuous bedside monitoring of local CBF (locCBF) in addition to the standard intracranial pressure and brain tissue oxygen tension (PbtO2) monitoring. The CBF probes were placed in the white matter using a separate cranial bolt. A pressure challenge, whereby mean arterial pressure (MAP) was increased by about 10 mm Hg, was performed in all patients to assess autoregulation. Cerebral CO2 vasoreactivity was assessed with a hyperventilation challenge. Local cerebral vascular resistance (locCVR) was calculated by dividing cerebral perfusion pressure by locCBF. Local cerebral vascular resistance normalized to baseline (locCVRnormalized) was also calculated for the MAP and hyperventilation challenges.
In all cases, bedside measurement of locCBF using a cranial bolt in patients with severe TBI resulted in correct placement in the white matter with a low rate of complications. Mean locCBF decreased substantially with hyperventilation challenge (−7 ± 8 ml/100 g/min, p = 0.0002) and increased slightly with MAP challenge (1 ± 7 ml/100 g/min, p = 0.17). Measurements of locCBF following MAP and hyperventilation challenges can be used to calculate locCVR. In 83% of cases, locCVR increased during a hyperventilation challenge (mean change +3.5 ± 3.8 mm Hg/ml/100 g/min, p = 0.0002), indicating preserved cerebral CO2 vasoreactivity. In contrast, we observed a more variable response of locCVR to MAP challenge, with increased locCVR in only 53% of cases during a MAP challenge (mean change −0.17 ± 3.9 mm Hg/ml/100 g/min, p = 0.64) indicating that in many cases autoregulation was impaired following severe TBI.
Use of the Hemedex thermal diffusion probe appears to be a safe and feasible method that enables continuous monitoring of CBF at the bedside. Cerebral autoregulation and CO2 vasoreactivity can be assessed in patients with severe TBI using the CBF probe by calculating locCVR in response to MAP and hyperventilation challenges. Determining whether CVR increases or decreases with a MAP challenge (locCVRnormalized) may be a simple provocative test to determine patients' autoregulatory status following severe TBI and helping to optimize CPP management.
Alexander C. Flint, Alisa D. Gean, Geoffrey T. Manley, Vivek A. Rao, William F. Sheridan and Cornelia S. von Koch
An acute subdural hematoma (SDH) requiring surgical intervention is treated with craniotomy or craniectomy, in part because it is generally accepted that coagulated blood present in the acute phase cannot be adequately evacuated by less-invasive means such as bur hole drainage. However, a hyperacute SDH in the first few hours after trauma can have mixed-density components on CT scans that are thought to represent subdural blood that is not yet fully coagulated.
The authors report a case in which a hyperacute SDH in a patient receiving antiplatelet therapy was treated with the novel technique of temporizing subdural evacuation port system (SEPS) placement. Placement of an SEPS in the intensive care unit allowed for rapid surgical treatment of the patient's elevated intracranial pressure (ICP) by drainage of 70 ml of fresh subdural blood. After initial SEPS-induced stabilization, the patient underwent operative treatment of the SDH by craniotomy. The combined approach of emergency SEPS placement followed by craniotomy resulted in a dramatic recovery, with improvement from coma and extensor posturing to a normal status on neurological evaluation 5 weeks later. In appropriately selected cases, patients with a hyperacute SDH may benefit from SEPS placement to quickly treat elevated ICP, as a bridge to definitive surgical treatment by craniotomy.
Ann-Christine Duhaime and Steven M. Stufflebeam
Phiroz E. Tarapore, Anne M. Findlay, Sara C. LaHue, Hana Lee, Susanne M. Honma, Danielle Mizuiri, Tracy L. Luks, Geoffrey T. Manley, Srikantan S. Nagarajan and Pratik Mukherjee
Traumatic brain injury (TBI) is one of the leading causes of morbidity worldwide. One mechanism by which blunt head trauma may disrupt normal cognition and behavior is through alteration of functional connectivity between brain regions. In this pilot study, the authors applied a rapid automated resting state magnetoencephalography (MEG) imaging technique suitable for routine clinical use to test the hypothesis that there is decreased functional connectivity in patients with TBI compared with matched controls, even in cases of mild TBI. Furthermore, they posit that these abnormal reductions in MEG functional connectivity can be detected even in TBI patients without specific evidence of traumatic lesions on 3-T MR images. Finally, they hypothesize that the reductions of functional connectivity can improve over time across serial MEG scans during recovery from TBI.
Magnetoencephalography maps of functional connectivity in the alpha (8- to 12-Hz) band from 21 patients who sustained a TBI were compared with those from 18 age- and sex-matched controls. Regions of altered functional connectivity in each patient were detected in automated fashion through atlas-based registration to the control database. The extent of reduced functional connectivity in the patient group was tested for correlations with clinical characteristics of the injury as well as with findings on 3-T MRI. Finally, the authors compared initial connectivity maps with 2-year follow-up functional connectivity in a subgroup of 5 patients with TBI.
Fourteen male and 7 female patients (17–53 years old, median 29 years) were enrolled. By Glasgow Coma Scale (GCS) criteria, 11 patients had mild, 1 had moderate, and 3 had severe TBI, and 6 had no GCS score recorded. On 3-T MRI, 16 patients had abnormal findings attributable to the trauma and 5 had findings in the normal range. As a group, the patients with TBI had significantly lower functional connectivity than controls (p < 0.01). Three of the 5 patients with normal findings on 3-T MRI showed regions of abnormally reduced MEG functional connectivity. No significant correlations were seen between extent of functional disconnection and injury severity or posttraumatic symptoms (p > 0.05). In the subgroup undergoing 2-year follow-up, the second MEG scan demonstrated a significantly lower percentage of voxels with decreased connectivity (p < 0.05) than the initial MEG scan.
A rapid automated resting-state MEG imaging technique demonstrates abnormally decreased functional connectivity that may persist for years after TBI, including cases classified as “mild” by GCS criteria. Disrupted MEG connectivity can be detected even in some patients with normal findings on 3-T MRI. Analysis of follow-up MEG scans in a subgroup of patients shows that, over time, the abnormally reduced connectivity can improve, suggesting neuroplasticity during the recovery from TBI. Resting state MEG deserves further investigation as a prognostic and predictive biomarker for TBI.
Angelos G. Kolias, Peter J. Hutchinson, David K. Menon, Geoffrey T. Manley, Clare N. Gallagher and Franco Servadei
Jason F. Talbott, William D. Whetstone, William J. Readdy, Adam R. Ferguson, Jacqueline C. Bresnahan, Rajiv Saigal, Gregory W. J. Hawryluk, Michael S. Beattie, Marc C. Mabray, Jonathan Z. Pan, Geoffrey T. Manley and Sanjay S. Dhall
Previous studies that have evaluated the prognostic value of abnormal changes in signals on T2-weighted MRI scans of an injured spinal cord have focused on the longitudinal extent of this signal abnormality in the sagittal plane. Although the transverse extent of injury and the degree of spared spinal cord white matter have been shown to be important for predicting outcomes in preclinical animal models of spinal cord injury (SCI), surprisingly little is known about the prognostic value of altered T2 relaxivity in humans in the axial plane.
The authors undertook a retrospective chart review of 60 patients who met the inclusion criteria of this study and presented to the authors’ Level I trauma center with an acute blunt traumatic cervical SCI. Within 48 hours of admission, all patients underwent MRI examination, which included axial and sagittal T2 images. Neurological symptoms, evaluated with the grades according to the American Spinal Injury Association (ASIA) Impairment Scale (AIS), at the time of admission and at hospital discharge were correlated with MRI findings. Five distinct patterns of intramedullary spinal cord T2 signal abnormality were defined in the axial plane at the injury epicenter. These patterns were assigned ordinal values ranging from 0 to 4, referred to as the Brain and Spinal Injury Center (BASIC) scores, which encompassed the spectrum of SCI severity.
The BASIC score strongly correlated with neurological symptoms at the time of both hospital admission and discharge. It also distinguished patients initially presenting with complete injury who improved by at least one AIS grade by the time of discharge from those whose injury did not improve. The authors’ proposed score was rapid to apply and showed excellent interrater reliability.
The authors describe a novel 5-point ordinal MRI score for classifying acute SCIs on the basis of axial T2-weighted imaging. The proposed BASIC score stratifies the SCIs according to the extent of transverse T2 signal abnormality during the acute phase of the injury. The new score improves on current MRI-based prognostic descriptions for SCI by reflecting functionally and anatomically significant patterns of intramedullary T2 signal abnormality in the axial plane.
Ethan A. Winkler, John K. Yue, Harjus Birk, Caitlin K. Robinson, Geoffrey T. Manley, Sanjay S. Dhall and Phiroz E. Tarapore
Traumatic fractures of the thoracolumbar spine are common injuries, accounting for approximately 90% of all spinal trauma. Lumbar spine trauma in the elderly is a growing public health problem with relatively little evidence to guide clinical management. The authors sought to characterize the complications, morbidity, and mortality associated with surgical and nonsurgical management in elderly patients with traumatic fractures of the lumbar spine.
Using the National Sample Program of the National Trauma Data Bank, the authors performed a retrospective analysis of patients ≥ 55 years of age who had traumatic fracture to the lumbar spine. This group was divided into middle-aged (55–69 years) and elderly (≥ 70 years) cohorts. Cohorts were subdivided into nonoperative, vertebroplasty or kyphoplasty, noninstrumented surgery, and instrumented surgery. Univariate and multivariable analyses were used to characterize and identify predictors of medical and surgical complications, mortality, hospital length of stay, ICU length of stay, number of days on ventilator, and hospital discharge in each subgroup. Adjusted odds ratios, mean differences, and associated 95% CIs were reported. Statistical significance was assessed at p < 0.05, and the Bonferroni correction for multiple comparisons was applied for each outcome analysis.
Between 2003 and 2012, 22,835 people met the inclusion criteria, which represents 94,103 incidents nationally. Analyses revealed a similar medical and surgical complication profile between age groups. The most prevalent medical complications were pneumonia (7.0%), acute respiratory distress syndrome (3.6%), and deep venous thrombosis (3%). Surgical site infections occurred in 6.3% of cases. Instrumented surgery was associated with the highest odds of each complication (p < 0.001). The inpatient mortality rate was 6.8% for all subjects. Multivariable analyses demonstrated that age ≥ 70 years was an independent predictor of mortality (OR 3.16, 95% CI 2.77–3.60), whereas instrumented surgery (multivariable OR 0.38, 95% CI 0.28–0.52) and vertebroplasty or kyphoplasty (OR 0.27, 95% CI 0.17–0.45) were associated with decreased odds of death. In surviving patients, both older age (OR 0.32, 95% CI 0.30–0.34) and instrumented fusion (OR 0.37, 95% CI 0.33–0.41) were associated with decreased odds of discharge to home.
The present study confirms that lumbar surgery in the elderly is associated with increased morbidity. In particular, instrumented fusion is associated with periprocedural complications, prolonged hospitalization, and a decreased likelihood of being discharged home. However, fusion surgery is also associated with reduced mortality. Age alone should not be an exclusionary factor in identifying surgical candidates for instrumented lumbar spinal fusion. Future studies are needed to confirm these findings.