Faculty Bibliography

BACKGROUND AND PURPOSE/OBJECTIVE:Because the corpus callosum connects the left and right hemispheres and a variety of WM bundles across the brain in complex ways, damage to the neighboring WM microstructure may specifically disrupt interhemispheric communication through the corpus callosum following mild traumatic brain injury. Here we use a mediation framework to investigate how callosal interhemispheric communication is affected by WM microstructure in mild traumatic brain injury. MATERIALS AND METHODS/METHODS:Multishell diffusion MR imaging was performed on 23 patients with mild traumatic brain injury within 1 month of injury and 17 healthy controls, deriving 11 diffusion metrics, including DTI, diffusional kurtosis imaging, and compartment-specific standard model parameters. Interhemispheric processing speed was assessed using the interhemispheric speed of processing task (IHSPT) by measuring the latency between word presentation to the 2 hemivisual fields and oral word articulation. Mediation analysis was performed to assess the indirect effect of neighboring WM microstructures on the relationship between the corpus callosum and IHSPT performance. In addition, we conducted a univariate correlation analysis to investigate the direct association between callosal microstructures and IHSPT performance as well as a multivariate regression analysis to jointly evaluate both callosal and neighboring WM microstructures in association with IHSPT scores for each group. RESULTS:Several significant mediators in the relationships between callosal microstructure and IHSPT performance were found in healthy controls. However, patients with mild traumatic brain injury appeared to lose such normal associations when microstructural changes occurred compared with healthy controls. CONCLUSIONS:This study investigates the effects of neighboring WM microstructure on callosal interhemispheric communication in healthy controls and patients with mild traumatic brain injury, highlighting that neighboring noncallosal WM microstructures are involved in callosal interhemispheric communication and information transfer. Further longitudinal studies may provide insight into the temporal dynamics of interhemispheric recovery following mild traumatic brain injury.

BACKGROUND AND PURPOSE/OBJECTIVE:Several recent works using resting-state fMRI suggest possible alterations of resting-state functional connectivity after mild traumatic brain injury. However, the literature is plagued by various analysis approaches and small study cohorts, resulting in an inconsistent array of reported findings. In this study, we aimed to investigate differences in whole-brain resting-state functional connectivity between adult patients with mild traumatic brain injury within 1 month of injury and healthy control subjects using several comprehensive resting-state functional connectivity measurement methods and analyses. MATERIALS AND METHODS/METHODS:A total of 123 subjects (72 patients with mild traumatic brain injury and 51 healthy controls) were included. A standard fMRI preprocessing pipeline was used. ROI/seed-based analyses were conducted using 4 standard brain parcellation methods, and the independent component analysis method was applied to measure resting-state functional connectivity. The fractional amplitude of low-frequency fluctuations was also measured. Group comparisons were performed on all measurements with appropriate whole-brain multilevel statistical analysis and correction. RESULTS:There were no significant differences in age, sex, education, and hand preference between groups as well as no significant correlation between all measurements and these potential confounders. We found that each resting-state functional connectivity measurement revealed various regions or connections that were different between groups. However, after we corrected for multiple comparisons, the results showed no statistically significant differences between groups in terms of resting-state functional connectivity across methods and analyses. CONCLUSIONS:Although previous studies point to multiple regions and networks as possible mild traumatic brain injury biomarkers, this study shows that the effect of mild injury on brain resting-state functional connectivity has not survived after rigorous statistical correction. A further study using subject-level connectivity analyses may be necessary due to both subtle and variable effects of mild traumatic brain injury on brain functional connectivity across individuals.

Post-traumatic stress disorder (PTSD) is a mental disorder diagnosed by clinical interviews, self-report measures and neuropsychological testing. Traumatic brain injury (TBI) can have neuropsychiatric symptoms similar to PTSD. Diagnosing PTSD and TBI is challenging and more so for providers lacking specialized training facing time pressures in primary care and other general medical settings. Diagnosis relies heavily on patient self-report and patients frequently under-report or over-report their symptoms due to stigma or seeking compensation. We aimed to create objective diagnostic screening tests utilizing Clinical Laboratory Improvement Amendments (CLIA) blood tests available in most clinical settings. CLIA blood test results were ascertained in 475 male veterans with and without PTSD and TBI following warzone exposure in Iraq or Afghanistan. Using random forest (RF) methods, four classification models were derived to predict PTSD and TBI status. CLIA features were selected utilizing a stepwise forward variable selection RF procedure. The AUC, accuracy, sensitivity, and specificity were 0.730, 0.706, 0.659, and 0.715, respectively for differentiating PTSD and healthy controls (HC), 0.704, 0.677, 0.671, and 0.681 for TBI vs. HC, 0.739, 0.742, 0.635, and 0.766 for PTSD comorbid with TBI vs HC, and 0.726, 0.723, 0.636, and 0.747 for PTSD vs. TBI. Comorbid alcohol abuse, major depressive disorder, and BMI are not confounders in these RF models. Markers of glucose metabolism and inflammation are among the most significant CLIA features in our models. Routine CLIA blood tests have the potential for discriminating PTSD and TBI cases from healthy controls and from each other. These findings hold promise for the development of accessible and low-cost biomarker tests as screening measures for PTSD and TBI in primary care and specialty settings.

BACKGROUND:Early neurorehabilitation improves outcomes in patients with disorders of consciousness (DoC) after brain injury, but its applicability in COVID-19 is unknown. We describe our experience implementing an early neurorehabilitation protocol for patients with COVID-19-associated DoC in the intensive care unit (ICU) and evaluate factors associated with recovery. METHODS:During the initial COVID-19 surge in New York City between March 10 and May 20, 2020, faced with a disproportionately high number of ICU patients with prolonged unresponsiveness, we developed and implemented an early neurorehabilitation protocol, applying standard practices from brain injury rehabilitation care to the ICU setting. Twenty-one patients with delayed recovery of consciousness after severe COVID-19 participated in a pilot early neurorehabilitation program that included serial Coma Recovery Scale-Revised (CRS-R) assessments, multimodal treatment, and access to clinicians specializing in brain injury medicine. We retrospectively compared clinical features of patients who did and did not recover to the minimally conscious state (MCS) or better, defined as a CRS-R total score (TS) ≥ 8, before discharge. We additionally examined factors associated with best CRS-R TS, last CRS-R TS, hospital length of stay, and time on mechanical ventilation. RESULTS:Patients underwent CRS-R assessments a median of six (interquartile range [IQR] 3-10) times before discharge, beginning a median of 48 days (IQR 40-55) from admission. Twelve (57%) patients recovered to MCS after a median of 8 days (IQR 2-14) off continuous sedation; they had lower body mass index (p = 0.009), lower peak serum C-reactive protein levels (p = 0.023), higher minimum arterial partial pressure of oxygen (p = 0.028), and earlier fentanyl discontinuation (p = 0.018). CRS-R scores fluctuated over time, and the best CRS-R TS was significantly higher than the last CRS-R TS (median 8 [IQR 5-23] vs. 5 [IQR 3-18], p = 0.002). Earlier fentanyl (p = 0.001) and neuromuscular blockade (p = 0.015) discontinuation correlated with a higher last CRS-R TS. CONCLUSIONS:More than half of our cohort of patients with prolonged unresponsiveness following severe COVID-19 recovered to MCS or better before hospital discharge, achieving a clinical benchmark known to have relatively favorable long-term prognostic implications in DoC of other etiologies. Hypoxia, systemic inflammation, sedation, and neuromuscular blockade may impact diagnostic assessment and prognosis, and fluctuations in level of consciousness make serial assessments essential. Early neurorehabilitation of these patients in the ICU can be accomplished but is associated with unique challenges. Further research should evaluate factors associated with longer-term neurologic recovery and benefits of early rehabilitation in patients with severe COVID-19.

BACKGROUND:Traumatic brain injury (TBI) often results in chronic impairments to cognitive function, and these may be related to disrupted functional connectivity (FC) of the brain at rest. OBJECTIVE:To investigate changes in default mode network (DMN) FC in adults with chronic TBI following 40 hours of auditory processing speed training. METHODS:Eleven adults with chronic TBI underwent 40-hours of auditory processing speed training over 13-weeks and seven adults with chronic TBI were assigned to a non-intervention control group. For all participants, resting-state FC and cognitive and self-reported function were measured at baseline and at a follow-up visit 13-weeks later. RESULTS:No significant group differences in cognitive function or resting-state FC were observed at baseline. Following training, the intervention group demonstrated objective and subjective improvements on cognitive measures with moderate-to-large effect sizes. Repeated measures ANCOVAs revealed significant (p <  0.001) group×time interactions, suggesting training-related changes in DMN FC, and semipartial correlations demonstrated that these were associated with changes in cognitive functioning. CONCLUSIONS:Changes in the FC between the DMN and other resting-state networks involved in the maintenance and manipulation of internal information, attention, and sensorimotor functioning may be facilitated through consistent participation in plasticity-based auditory processing speed training in adults with chronic TBI.

PURPOSE OF REVIEW/OBJECTIVE:Concussion produces a variety of signs and symptoms. Most patients recover within 2-4 weeks, but a significant minority experiences persistent post-concussive symptoms (PPCS), some of which may be from associated cervical or persistent neurologic sub-system (e.g., vestibular) dysfunction. This review provides evidence-based information for a pertinent history and physical examination of patients with concussion. RECENT FINDINGS/RESULTS:The differential diagnosis of PPCS is based on the mechanism of injury, a thorough medical history and concussion-pertinent neurological and cervical physical examinations. The concussion physical examination focuses on elements of autonomic function, oculomotor and vestibular function, and the cervical spine. Abnormalities identified on physical examination can inform specific forms of rehabilitation to help speed recovery. Emerging data show that there are specific symptom generators after concussion that can be identified by a thorough history, a pertinent physical examination, and adjunct tests when indicated.

PURPOSE OF REVIEW/OBJECTIVE:Concussion is a complex injury that may present as a variety of clinical profiles, which can overlap and reinforce one another. This review summarizes the medical management of patients with concussion and persistent post-concussive symptoms (PPCS). RECENT FINDINGS/RESULTS:Management of concussion and PPCS relies on identifying underlying symptom generators. Treatment options include sub-symptom threshold aerobic exercise, cervical physical therapy, vestibular therapy, vision therapy, cognitive rehabilitation, cognitive behavioral therapy, pharmacological management, or a combination of treatments. Evidence-based treatments have emerged to treat post-concussion symptom generators for sport-related concussion and for patients with PPCS.