Cervico-ocular coordination during neck rotation is distorted in people with whiplash-associated disorders

Abstract

People with whiplash-associated disorders (WAD) not only suffer from neck/head pain, but commonly report deficits in eye movement control. Recent work has highlighted a strong relationship between eye and neck muscle activation in pain-free subjects. It is possible that WAD may disrupt the intricate coordination between eye and neck movement. Electromyographic activity (EMG) of muscles that rotate the cervical spine to the right (left sternocleidomastoid, right obliquus capitis inferior (OI), right splenius capitis (SC) and right multifidus (MF)) was recorded in nine people with chronic WAD. Cervical rotation was performed with five gaze conditions involving different gaze directions relative to cervical rotation. The relationship between eye position/movement and neck muscle activity was contrasted with previous observations from pain-free controls. Three main differences were observed in WAD. First, the superficial muscle SC was active with both directions of cervical rotation in contrast to activity only with right rotation in pain-free controls. Second, activity of OI and MF varied between directions of cervical rotation, unlike the non-direction-specific activity in controls. Third, the effect of horizontal gaze direction on neck muscle EMG was augmented compared to controls. These observations provide evidence of redistribution of activity between neck muscles during cervical rotation and increased interaction between eye and neck muscle activity in people with WAD. These changes in cervico-ocular coordination may underlie clinical symptoms reported by people with WAD that involve visual deficits and changes in function during cervical rotation such as postural control.

The influence of cervical movement on eye stabilization reflexes: a randomized trial

“…Neck pain patients show sensorimotor disturbances that are often related to pain, diminished range of motion, quality of movement, and oculomotor disturbances (Storaci et al 2006;Treleaven 2008;Kristjansson and Treleaven 2009;Bexander and Hodges 2012;Kristjansson et al 2016;Stenneberg et al 2016). These oculomotor disturbances can provoke blurred vision, dizziness and the need to concentrate more than usual when reading (Treleaven and Takasaki 2014).…”

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

“…Electromyography (EMG) studies have shown that not all dorsal muscles act synergistically as extensors; the splenius capitis muscle can activate during neck flexion in some healthy individuals (Keshner et al 1989) and higher levels of extensor muscle co-activation in neck pain have been reported (Lindstrom et al 2011). Surface EMG has demonstrated increased activity in superficial neck extensors in WAD (Bexander et al 2012, Juul-Kristensen et al 2013), but when controlling for differences in movement velocity, no differences were found between WAD and healthy controls (Vikne et al 2013). Small invasive EMG studies have reported decreased and less defined activity in the deep semispinalis cervicis muscle in WAD (Schomacher et al 2012), and the multifidus muscle was affected by eye movement (Bexander et al 2012).…”

“…Surface EMG has demonstrated increased activity in superficial neck extensors in WAD (Bexander et al 2012, Juul-Kristensen et al 2013), but when controlling for differences in movement velocity, no differences were found between WAD and healthy controls (Vikne et al 2013). Small invasive EMG studies have reported decreased and less defined activity in the deep semispinalis cervicis muscle in WAD (Schomacher et al 2012), and the multifidus muscle was affected by eye movement (Bexander et al 2012). Both the expensive MRI and invasive EMG are difficult to apply in routine clinical practice and MRI does not provide information on the interplay between muscle layers.…”

Neck muscle function in individuals with persistent pain and disability after whiplash injury

“…Impaired ventral neck muscle function with increased activity in the superficial SCM muscle and delayed activity in the deep muscles in neck pain (25,27) have been shown in WAD. Also in the dorsal neck muscles, increased activity in superficial neck extensors in WAD has been seen (28,45), but a study controlling for differences in movement velocity reported no differences between WAD and healthy controls (46). Two small studies have reported altered deep dorsal neck muscle function in WAD.…”

“…Two small studies have reported altered deep dorsal neck muscle function in WAD. A less defined and decreased activation in the semispinalis cervices muscle was reported (29) and the multifidus muscle was affected by eye movements (45).…”