The Rapid and Progressive Degeneration of the Cervical Multifidus in Whiplash

Abstract

Study Design Single-center prospective longitudinal study Objective To study the 1) temporal development of muscle fatty infiltrates (MFI) in the cervical multifidii following whiplash, 2) differences in multifidii MFI between those who recover or report milder pain related disability from those who report moderate/severe symptoms at 3 months, and 3) predictive value of multifidii MFI outcomes. Summary of Background Data The temporal development of MFI on conventional MRI has been shown to be associated with specific aspects of pain and psychological factors. The replication of such findings has yet to be explored longitudinally. Methods 36 subjects with whiplash injury were enrolled at < 1-week post-injury and classified at 3-months using percentage scores on the Neck Disability Index as recovered/mild (0–28%) or severe (≥ 30%). A fat/water MRI measure, patient self-report of pain related disability and post-traumatic stress were collected at <1-week, 2-weeks and 3-months post-injury. The effects of time and group (per NDI) and the interaction of time by group on MFI were determined. Receiver operating characteristic curve (ROC) analysis was used to determine a cut-point for MFI at 2 weeks to predict outcome at 3 months. Results There was no difference in MFI across groups at enrolment. MFI values were significantly higher in the severe group when compared to the recovered/mild group at 2-weeks and 3-months.The ROC analysis indicated that MFI levels of 20.5% or above resulted in a sensitivity of 87.5% and a specificity of 92.9% for predicting outcome at 3 months. Conclusions Consistent with previous evidence, muscle degeneration occurs soon after injury but only in those patients with poor functional recovery. This study provides further evidence that 1) multifidii MFI occurs in tandem with known predictive risk factors (older age, pain-related disability, and post-traumatic stress) and that 2) routine imaging protocols may need to be reconsidered in the vast majority of patients following whiplash.

Recovery Pathways and Prognosis After Whiplash Injury

“…3,8,18,30 The availability of large epidemiological data sets 30 and access to jurisdictional administrative databases 3,8 have allowed specific prognostic factors collected before the whiplash injury to be assessed for their influence on recovery following an MVC. For example, higher use of sick leave prior to an MVC has been shown to be predictive of prolonged recovery following whiplash injury, 8 and preinjury use of multiple health services and elevated use of medications have been shown to predict ongoing pain postwhiplash.…”

“…18 At this stage, the data are not robust enough to suggest that early imaging is necessary, and, in fact, clinical guidelines recommend that early imaging not be provided to the vast majority of individuals postwhiplash. 29 However, there is emerging evidence to show that levels of muscle fatty infiltrates in cervical spine muscles measured 2 weeks postinjury are associated with neck disability at 3 months postinjury.…”

“…29 However, there is emerging evidence to show that levels of muscle fatty infiltrates in cervical spine muscles measured 2 weeks postinjury are associated with neck disability at 3 months postinjury. 18 The mechanisms that cause the muscle fatty infiltrates are not known; however, in the future, this type of research may prove important to our understanding of processes underlying nonrecovery from a whiplash injury. 18 Finally, another challenge of translating the findings of prognostic-type research into clinical practice is that quantifiable cut points are rarely provided for prognostic variables.…”

An Integrated Model of Chronic Whiplash-Associated Disorder

“…32,34 The model then moves through primary sequelae that are often cited as clinical components of the spectrum of WAD: sensory hyperalgesia 87 (local or widespread mechanical, thermal, acoustic, photic, osmic), fear of pain or movement, 2 cognitive interference, 91 and impaired tissue health (eg, muscle fatty infiltration, atrophy, reduced tensile strength). 30,31,33,35 As the primary sequelae persist, secondary sequelae emerge that include sensorimo- tor incongruence (distorted body schema, disturbed proprioception, oculomotor and postural deficits), withdrawal from valued life roles, a sense of isolation, hopelessness, hypervigilance toward threat cues, and obstruction of a satisfying life trajectory. Dissociation has been included here as a potential alternative to hypervigilance.…”

The Physiological Basis of Cervical Facet-Mediated Persistent Pain: Basic Science and Clinical Challenges

“…101 Poor and chronic clinical outcomes are associated with baseline NDI scores greater than 30/100. 30,93 More recently, NDI scores greater than 30/100 (or 15/50) have also been identified as a predictor and significant risk factor of poor patient outcomes. 104 In a study of patients with whiplash, those with a baseline NDI score of greater than 30 also showed signs of generalized hypersensitivity, suggesting a relationship between nonevoked spontaneous pain and central sensitization.…”