Development of motor system dysfunction following whiplash injury

Abstract

Dysfunction in the motor system is a feature of persistent whiplash associated disorders. Little is known about motor dysfunction in the early stages following injury and of its progress in those persons who recover and those who develop persistent symptoms. This study measured prospectively, motor system function (cervical range of movement (ROM), joint position error (JPE) and activity of the superficial neck flexors (EMG) during a test of cranio-cervical flexion) as well as a measure of fear of re-injury (TAMPA) in 66 whiplash subjects within 1 month of injury and then 2 and 3 months post injury. Subjects were classified at 3 months post injury using scores on the neck disability index: recovered (<8), mild pain and disability (10-28) or moderate/severe pain and disability (>30). Motor system function was also measured in 20 control subjects. All whiplash groups demonstrated decreased ROM and increased EMG (compared to controls) at 1 month post injury. This deficit persisted in the group with moderate/severe symptoms but returned to within normal limits in those who had recovered or reported persistent mild pain at 3 months. Increased EMG persisted for 3 months in all whiplash groups. Only the moderate/severe group showed greater JPE, within 1 month of injury, which remained unchanged at 3 months. TAMPA scores of the moderate/severe group were higher than those of the other two groups. The differences in TAMPA did not impact on ROM, EMG or JPE. This study identifies, for the first time, deficits in the motor system, as early as 1 month post whiplash injury, that persisted not only in those reporting moderate/severe symptoms at 3 months but also in subjects who recovered and those with persistent mild symptoms.

The rapid and progressive degeneration of the cervical multifidus in whiplash: A MRI study of fatty infiltration

“…1 Half of all those exposed to a MVC will never fully recover but have milder symptoms, 2 and 25% (~ 1 million) are expected to present with a complex clinical picture including severe-pain-related disability, 3 muscle degeneration, 4,5 sensory and motor disturbances, 6 muscle weakness, 7 and psychological distress. 6 A number of psychosocial factors (e.g., coping, expectations, anxiety and depression) have been identified as being associated with poor functional recovery.…”

Changes in Dorsal Neck Muscle Function in Individuals with Chronic Whiplash-Associated Disorders: A Real-Time Ultrasound Case–Control Study

“…The neck muscles surrounding the cervical spine and the deep neck muscle layers play an important role in maintaining a stable base for the postural control of the neck (Mayoux-Benhamou et al 1994, Panjabi 1992. Impaired ventral neck muscle function has been reported in chronic neck pain (Falla et al 2004, Falla et al 2011) and WAD (Cagnie et al 2010, Elliott et al 2010, Peterson et al 2015a, Sterling et al 2003, but the function of the neck extensor muscles in WAD are not as well studied. Elliott et al (2008a) demonstrated fatty infiltrate in the extensor muscle in WAD using magnetic resonance imaging (MRI).…”

Thoracic dysfunction in whiplash associated disorders: a systematic review

“…From this review we identified evidence of the following dysfunction,: thoracic spine pain in acute/sub-acute/chronic WAD ranging from minor injuries to more severe (WADIII) presentations [11,14,17,32,33,43,50,52,58,62]; chest pain in acute/sub-acute/chronic WAD [11,17,52,53]; postural changes [44,61] and reduced chest/thoracic mobility in CWAD [61]; thoracic outlet syndrome in CWAD [31,35,36,47,51]; involvement of the brachial plexus at all stages and across all levels of WAD severity [12,46,55,57,59]; muscle dysfunction in the form of the following: 1) heightened activity of the sternocleidomastoid during neck flexion [12,56], 2) delayed onset of serratus anterior during arm elevation at the chronic stage in mild WAD [45] and 3) a high prevalence of myofascial pain and trigger points in the scalene muscles [40,41], sternocleidomastoid [37,40,41] and mid/lower fibres of trapezius [16] within the subacute and chronic stages and across different levels of severity.…”

“…There are limited and very variable findings of thoracic muscle dysfunction (activation) in WAD with studies investigating a relatively small number of muscles: sternocleidomastoid [12,49,56]; serratus anterior [45]; middle and lower fibres of trapezius [45,54]. Although it is difficult to derive meaningful conclusions with respect to serratus anterior and trapezius, there is evidence supporting changes in sternocleidomastoid muscle activation with heightened levels of activation during a task of cranio-cervical flexion; this increase in sternocleidomastoid activity however, was not seen during neck rotation [49].…”