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The influence of neck pain on balance and gait parameters

July 13, 2008 on 5:18 pm | In Neck Pain |

The influence of neck pain on balance and gait parameters in community-dwelling elders

From: Man Ther. Volume 13, Issue 4, Pages 317-324 (August 2008)

Neck pain has been shown to be associated with balance disturbances. Balance and gait speed are also known to decline with ageing. The aim of this study was to determine whether the presence of neck pain was associated with a decline in postural stability and gait speed over and above what is expected with normal ageing. Twenty female subjects with idiopathic neck pain and 20 healthy female controls aged between 65 and 82 years were studied. Subjects performed balance tests on a computerised force plate under conditions of eyes open, eyes closed on firm and soft surfaces in comfortable and narrow stance. Sway energy and root mean square (RMS) amplitude of sway were measured. Subjects also undertook a Timed Ten Metre Walk Test, with and without head turning.

Age-related functional decline in the motor and sensory systems may affect balance function. Balance and postural control have been shown to decline with age and the role of factors such as vestibular function, motor control of back and pelvic musculature and muscle strength has been investigated in elderly people.

Musculoskeletal conditions, and specifically neck pain in this instance, might also contribute to balance deficits in the elderly. Neck pain is not uncommon in this age group. March et al. documented a neck pain prevalence of 40.5% in elderly women and 36.1% in elderly men living independently in the community. Cervical afferent input is an important contributor to balance and balance disturbances have been documented in young and middle aged individuals with neck pain of both insidious and traumatic onset. Subsequent improvements in balance have been demonstrated following localised treatment to the cervical spine.

In the absence of vestibular pathology, such disturbances are considered to result from altered cervical somatosensory input and integration in the postural control system. McPartland et al. determined a significant correlation between poor balance control and fatty infiltration of the cervical extensor musculature in those with neck pain and others have demonstrated the adverse effects of neck extensor muscle fatigue on postural sway. Stimulation of the muscle spindle afferents via neck muscle vibration has also been shown to not only increase postural sway but also influence the velocity and direction of gait and running in asymptomatic healthy individuals.

As a significant number of elderly persons in the community experience neck pain, we questioned whether or not there was a relationship between neck pain and a further decline in balance and/or gait parameters in the aged. Although balance and gait speed declines with age, both poor balance and slowness of gait have been recognised as risk factors for falls. If a relationship exists, it is possible that specific treatment directed to the neck pain may help to reduce the contributors to balance and gait disorders and risk of falls in this group. Thus, the aim of the study was to determine if any differences existed in selected standing balance tests and gait speed parameters between elderly subjects with neck pain when compared to elderly subjects without neck pain.

The results of this study demonstrate that elderly subjects with neck pain demonstrate some deficits in standing balance and gait parameters when compared to asymptomatic elderly subjects, which may alter their functional balance and gait ability and possibly increase their risk of falling. These findings point to the need to consider the contribution of a cervical disorder to balance and gait speed deficiencies in the older person. They also point to the need for routine assessment of these parameters in all elderly patients presenting for either treatment of neck pain or conversely for falls prevention programs if treatment programs are to be holistic.

There were trends for increased postural activity on all static standing tests in the neck pain group, although a significant increase in both amplitude (RMS) and energy of sway was present in only two of the eight test conditions (eyes closed on a firm surface in comfortable stance and eyes open on a firm surface in narrow stance). An increase in amplitude but not energy was seen in one other test (eyes open on a soft surface in comfortable stance). There were no test conditions where energy, but not amplitude, was significantly higher in the neck pain group. Increases in amplitude of sway in the neck pain group suggest that these subjects may have a decreased awareness of altered stability. The result is an increase in amplitude of sway rather than the subject choosing a stiffening strategy to maintain stability. A stiffening strategy would present as a high energy (frequency) but a reduced amplitude sway path.

It has been suggested that changes measured on the force platform tests may be associated with an increase risk of falls. Specifically, Melzer et al. demonstrated an increase in ML sway in narrow stance in elders with recurrent falls. Others have also noted an association between an increase in ML RMS sway amplitude during normal standing and future falls in elderly subjects. In the current study, there was an increase in ML RMS amplitude and energy of sway in narrow stance with eyes open in the neck pain group. However, all other significant differences were related to changes in the AP direction. Further research is warranted to determine the significance of these findings from the force platform in relation to risk of falls and altered functional balance ability in elderly with neck pain.

The Timed Ten Metre Walk Test revealed that elderly subjects with neck pain had a slower self-selected gait speed and cadence when walking whilst turning their head from side to side and a significantly longer gait cycle duration when walking both with and without head turns. These results suggest that those with neck pain were more cautious or apprehensive with their walking. Additionally turning the neck may cause pain or elicit fear of pain, which may further alter cervical somatosensory input to the postural control system, which could subsequently exacerbate balance and gait difficulties. The differences in gait parameters could also be a consequence of a dual tasking. Toulotte et al. recently found no change in gait parameters between fallers and non-fallers in a single task condition but significant changes when subjects were asked to perform another task while walking.

Such changes in gait quality measured in the current study may place those with neck pain at a greater risk of falls than non- neck pain elderly subjects. Wolfson et al. demonstrated that stride length, walking velocity and gait quality were reduced in elderly nursing home residents with a history of falls compared to control subjects. and Brauer et al. have also reported differences in stride length and walking speed between fallers and control subjects in community dwelling elderly. Self-selected gait speed is a predictor of self-perceived function. Nevertheless the average gait velocity demonstrated by the neck pain subjects in this study was still relatively high (greater than 1.1ms) and thus may not necessarily relate to functional deficits. Further research is required to determine any clinical significance of the changes to gait in the neck pain population.

The differences between the groups in this study could not be attributed to co-morbidities or medication intake. It is known that both use of more than four medications and the greater the number of co-morbidities a person has, the greater their risk of falls. Therefore, we specifically excluded any person with more than four co-morbidities and/or taking more than four medications, which challenged recruitment in the elderly population in this study. There were no differences between groups with respect to the number of co-morbidities, but the neck pain group, on average, took a greater number of medications. The number of medications taken was included as a covariate in the analysis but did not influence the differences in balance seen between the groups, a feature previously determined in a younger population with neck pain.

Despite relatively small subject numbers, the results of this study suggest that older persons with neck pain demonstrate some disturbances to their balance and gait over and above those, which occur with normal ageing. Such disturbances are likely due to altered cervical somotosensory input and integration to the postural control system. Functional impairment of cervical muscle and joint receptors such as muscle fatigue altered muscle spindle activity due to the presence of inflammatory mediators and the effects of pain itself on both nociceptor and mechanoreceptor activity locally, at the spinal cord and within the central nervous system, are possible mechanisms of altered cervical input.

The results of this study suggest that clinicians might consider management of neck pain and specific exercises to improve cervical afferent input in programmes directed at prevention of falls in older age and conversely, consider balance and gait assessment in those elders presenting with neck pain.