Persistent cognitive deficits after whiplash injury: a comparative study with mild traumatic brain injury patients and healthy volunteers

Brain Connectivity Predicts Chronic Pain in Acute Mild Traumatic Brain Injury

OBJECTIVES

Previous studies have established the role of the cortico-mesolimbic and descending pain modulation systems in chronic pain prediction. Mild traumatic brain injury (mTBI) is an acute pain model where chronic pain is prevalent and complicated for prediction. In this study, we set out to study whether functional connectivity (FC) of the nucleus accumbens (NAc) and the periaqueductal gray matter (PAG) is predictive of pain chronification in early-acute mTBI.

METHODS

To estimate FC, resting-state functional magnetic resonance imaging (fMRI) of 105 participants with mTBI following a motor vehicle collision was acquired within 72 hours post-accident. Participants were classified according to pain ratings provided at 12-months post-collision into chronic pain (head/neck pain ≥30/100, n = 44) and recovery (n = 61) groups, and their FC maps were compared.

RESULTS

The chronic pain group exhibited reduced negative FC between NAc and a region within the primary motor cortex corresponding with the expected representation of the area of injury. A complementary pattern was also demonstrated between PAG and the primary somatosensory cortex. PAG and NAc also shared increased FC to the rostral anterior cingulate cortex (rACC) within the recovery group. Brain connectivity further shows high classification accuracy (area under the curve [AUC] = .86) for future chronic pain, when combined with an acute pain intensity report.

INTERPRETATION

FC features obtained shortly after mTBI predict its transition to long-term chronic pain, and may reflect an underlying interaction of injury-related primary sensorimotor cortical areas with the mesolimbic and pain modulation systems. Our findings indicate a potential predictive biomarker and highlight targets for future early preventive interventions. ANN NEUROL 2022;92:819-833.

Translationally Relevant Magnetic Resonance Imaging Markers in a Ferret Model of Closed Head Injury

Pre-clinical models of traumatic brain injury (TBI) have been the primary experimental tool for understanding the potential mechanisms and cellular alterations that follow brain injury, but the human relevance and translational value of these models are often called into question. Efforts to better recapitulate injury biomechanics and the use of non-rodent species with neuroanatomical similarities to humans may address these concerns and promise to advance experimental studies toward clinical impact. In addition to improving translational aspects of animal models, it is also advantageous to establish pre-clinical outcomes that can be directly compared with the same outcomes in humans. Non-invasive imaging and particularly MRI is promising for this purpose given that MRI is a primary tool for clinical diagnosis and at the same time increasingly available at the pre-clinical level. The objective of this study was to identify which commonly used radiologic markers of TBI outcomes can be found also in a translationally relevant pre-clinical model of TBI. The ferret was selected as a human relevant species for this study with folded cortical geometry and relatively high white matter content and the closed head injury model of engineered rotation and acceleration (CHIMERA) TBI model was selected for biomechanical similarities to human injury. A comprehensive battery of MRI protocols based on common data elements (CDEs) for human TBI was collected longitudinally for the identification of MRI markers and voxelwise analysis of T2, contrast enhancement and diffusion tensor MRI values. The most prominent MRI findings were consistent with focal hemorrhage and edema in the brain stem region following high severity injury as well as vascular and meningeal injury evident by contrast enhancement. While conventional MRI outcomes were not highly conspicuous in less severe cases, quantitative voxelwise analysis indicated diffusivity and anisotropy alterations in the acute and chronic periods after TBI. The main conclusions of this study support the translational relevance of closed head TBI models in intermediate species and identify brain stem and meningeal vulnerability. Additionally, the MRI findings highlight a subset of CDEs with promise to bridge pre-clinical studies with human TBI outcomes.

Head- and neck-related symptoms post-motor vehicle collision (MVC): Separate entities or two-sides of the same coin?

BACKGROUND AND AIM

Although post-motor vehicle collision (MVC) pain and symptoms are largely convergent among those with mild traumatic brain injury (mTBI) and whiplash associated disorder (WAD), and patients oftentimes report initial neck and head complaints, the clinical picture of mTBI and WAD has been primarily studied as separate conditions which may result in an incomplete clinical picture. As such, this study was conducted to explore the role of pain and post-traumatic psychological features in explaining both head and neck-related symptom variability in a cohort of post-collision patients. This is with the goal of disentangling if contributory factors are uniquely related to each diagnosis, or are shared between the two.

METHODS

Patients recruited in the very early acute phase (<72 h) returned for clinical and psychological assessment at 6 months post-accident. In order to determine which factors were unique and which ones were overlapping the same potential contributors: mean head pain, mean neck pain, female gender, number of post-collision painful body areas, PTSD, and depression were included in the regression models for both neck disability index (NDI) and Rivermead post-concussion symptoms questionnaire (RPQ).

RESULTS

Of 223 recruited participants, 70 returned for a follow-up visit (age range 18-64, mean(SD) 37.6 (11.9), 29F). This cohort primarily met the criteria for mTBI, but also fulfilled the criteria for whiplash, reinforcing the duality of injury presentation. Correlations existed between the NDI and RPQ scores (Spearman's ρ=0.66, p<0.001), however overlap was only partial. Regression analysis showed that after the removal of area-of-injury pain neck related disability (r = 0.80, p <0.001) was explained solely by number of painful body areas (ß=0.52, p <0.001). In contrast, post-concussion syndrome symptoms (r = 0.86, p<0.001) are influenced by clinical pain, painful body areas (ß=0.31, p = 0.0026), female gender (ß=0.19, p = 0.0053), and psychological factors of depression (ß=0.31, p = 0.0028) and PTSD symptoms (ß=0.36, p = 0.0013).

CONCLUSIONS

It seems that while mechanisms of neck- and head-related symptoms in post-collision patients do share a common explanatory feature, of residual body pain, they are not entirely overlapping. In that psychological factors influence post-concussion syndrome symptoms, but not post-whiplash neck disability.

How similar are whiplash and mild traumatic brain injury? A systematic review

INTRODUCTION

Mild traumatic brain injury (mTBI) and whiplash are two pathologies which appear in the follow-up of a cranio-cervical trauma. The objective of this study is to review their definitions, to discuss each entity.

METHODS

Whiplash and mTBI were defined. Then, a systematic literature review was carried out using the Pubmed database. Relevant studies after 1995 were selected, with 16 articles describing a link between whiplash and mTBI. 8 articles were analyzed after reading their abstracts.

RESULTS

Whiplash and mTBI have many similarities (symptoms, biomechanics, cognitive disorders, presence of diffuse axonal lesions on functional imaging) and some differences (in posture, more vestibular and balance disorders in whiplash). mTBIs result from linear accelerations between 60- 160g (gravity), studies on whiplash have shown that they can appear from 4.5g, which could explain biomechanically the frequent concomitant appearance. Cervical joint dysfunction can appear in persistent concussive syndrome, with upper cervical pain, less endurance of the cervical flexor muscles, and an increase in cervical stiffness leading to tension headache. This could explain neck pain in mTBI and headache in whiplash. An explanation to vestibular and cochlear disorders is given, and the two pathologies concomitantly could increase the symptoms.

CONCLUSION

To our knowledge, no studies define distinct boundaries between these two pathologies, which overlap on many points. An explanation is their concomitant onset, due to the biomechanics of the trauma and anatomical reasons. Larger-scale studies of rigorous scientific quality are needed to answer the question of the difference between whiplash and mTBI.

Contribution of the neuropsychological assessment in concussion

INTRODUCTION

The neuropsychological assessment is a cornerstone in the care management of concussion or mild traumatic injury.

OBJECTIVE

To present the different stages of an exhaustive neuropsychological assessment exploring cognitive and behavioral domains.

METHOD

Description of the value of the main tests available for behavioral and cognitive assessment. The choice of tests is based on the clinical experience and expertise of the authors.

RESULTS

Questionnaires are mainly used to explore the behavioral sequelae (depression, anxiety or fatigue) and the impact of these potential difficulties in daily life. Four cognitive abilities could be impaired by concussion: attention, memory, visuospatial functions and executive functions. These abilities could be explored with "paper and pencil" tests or with computerized test batteries. While cognitive sequelae in the context of a moderate or a severe traumatic brain injury are consolidated, in the context of concussion, neuropsychological sequelae tend to resolve in a short time. As a consequence, several neuropsychological assessments could be conducting in a short period involving some methodological considerations. Moreover, as concussion could be reported in a Whiplash injury from a car crash with forensic consequences, it is crucial to propose tests to be sure that the weak performance obtained into the neuropsychological assessment is not explained by poor effort and/or malingering.

DISCUSSION/CONCLUSION

This article revises these aspects of a neuropsychological assessment in the specific context of concussion.

Brain Network Disruption in Whiplash

BACKGROUND AND PURPOSE

Whiplash-associated disorders frequently develop following motor vehicle collisions and often involve a range of cognitive and affective symptoms, though the neural correlates of the disorder are largely unknown. In this study, a sample of participants with chronic whiplash injuries were scanned by using resting-state fMRI to assess brain network changes associated with long-term outcome metrics.

MATERIALS AND METHODS

Resting-state fMRI was collected for 23 participants and used to calculate network modularity, a quantitative measure of the functional segregation of brain region communities. This was analyzed for associations with whiplash-associated disorder outcome metrics, including scales of neck disability, traumatic distress, depression, and pain. In addition to these clinical scales, cervical muscle fat infiltration was quantified by using Dixon fat-water imaging, which has shown promise as a biomarker for assessing disorder severity and predicting recovery in chronic whiplash.

RESULTS

An association was found between brain network structure and muscle fat infiltration, wherein lower network modularity was associated with larger amounts of cervical muscle fat infiltration after controlling for age, sex, body mass index, and scan motion (t = -4.02, partial R ²  = 0.49, P < .001).

CONCLUSIONS

This work contributes to the existing whiplash literature by examining a sample of participants with whiplash-associated disorder by using resting-state fMRI. Less modular brain networks were found to be associated with greater amounts of cervical muscle fat infiltration suggesting a connection between disorder severity and neurologic changes, and a potential role for neuroimaging in understanding the pathophysiology of chronic whiplash-associated disorders.

Can the Neck Contribute to Persistent Symptoms Post Concussion? A Prospective Descriptive Case Series

BACKGROUND

Persistent symptoms post concussion can arise from a range of sources, including the neck. There is little description of neck assessment findings in people with persistent symptoms post concussion.

OBJECTIVES

To assess people with persistent symptoms following a concussion and determine whether the neck has also been injured, and to evaluate the potential of the neck to contribute to their symptoms.

METHODS

A consecutive series of participants (n = 20) referred for neck assessment were prospectively recruited by 2 providers of a multidisciplinary concussion service for people with persistent symptoms. Data were collected at initial assessment and on completion of neck treatment, which included standard questionnaires (Rivermead Post Concussion Symptoms Questionnaire, Neck Disability Index, Dizziness Handicap Inventory); patient-reported measures of headache, dizziness, and neck pain; physical examination findings; and details of comorbidities.

RESULTS

Participants were evaluated at a mean of 7.5 weeks post concussion (median, 5 weeks). On neck assessment, 90% were considered by the clinician to have a neck problem contributing to their current symptoms. Multiple findings were consistent with this view, including moderate-to-severe Neck Disability Index scores (mean ± SD, 33.4 ± 9.5 points), frequent neck pain (85%), frequent moderate-to-severe pain on occiput-C4 segmental assessment (85%), a positive flexion-rotation test (45%), and muscle tenderness (50%-55%).

CONCLUSION

Multiple findings were indicative of concurrent neck injury, particularly involving the upper cervical spine. These neck-related findings are important to recognize, as they have the potential to contribute to persistent symptoms post concussion and may respond to neck treatment. This study was prospectively registered with the Australian New Zealand Clinical Trials Registry (ACTRN12616001183471). J Orthop Sports Phys Ther 2019;49(11):845-854. Epub 1 Jun 2019. doi:10.2519/jospt.2019.8547.

Concussion in Combination With Whiplash-Associated Disorder May Be Missed in Primary Care: Key Recommendations for Assessment and Management

Whiplash and concussion may have similar presenting symptoms, biomechanical mechanisms, and neurophysiological sequelae, but neither enjoys a gold standard diagnostic test. Guidelines for whiplash and concussion are developed and implemented separately. This disparate process may contribute to misdiagnosis, delay appropriate primary care management, and impair patient outcomes. In our clinical commentary, we present 3 cases where signs and symptoms consistent with whiplash were identified in primary care. Symptoms in all cases included neck pain, headache, dizziness, and concentration deficits, raising suspicion of coexisting postconcussion syndrome. All cases were referred for specialist physical therapy. Characteristics consistent with poor recovery in both whiplash and postconcussion syndrome were confirmed, and multidisciplinary management, drawing from both whiplash and concussion guidelines, was implemented. All patients reported improvement in activities of daily living after tailored management addressing both neck and head injury-related factors, suggesting that these conditions were not mutually exclusive. Self-reported outcomes included reductions in neck disability and postconcussion symptoms of between 20% and 40%. It may be appropriate for whiplash and concussion guidelines to be amalgamated, enhanced, and mutually recognized on a patient-by-patient basis. Primary health care professionals might consider minimum screening to identify postconcussion syndrome in patients following motor vehicle collision by administering questionnaires and assessing cranial nerve function, balance, and cognition. Management should then incorporate principles from both whiplash and concussion guidelines and harmonize with available imaging guidelines for suspected spine and head trauma. J Orthop Sports Phys Ther 2019;49(11):819-828. doi:10.2519/jospt.2019.8946.

Sleep and Psychiatric Disorders in Persons With Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) frequently challenges the integrity of sleep function by affecting multiple brain areas implicated in controlling the switch between wakefulness and sleep and those involved in circadian and homeostatic processes; the malfunction of each causes a variety of disorders. In this review, we discuss recent data on the dynamics between disorders of sleep and mental/psychiatric disorders in persons with mTBI. This analysis sets the stage for understanding how a variety of physiological, emotional and environmental influences affect sleep and mental activities after injury to the brain. Consideration of the intricate links between sleep and mental functions in future research can increase understanding on the underlying mechanisms of sleep-related and psychiatric comorbidity in mTBI.