Muscle fiber conduction velocity of the upper trapezius muscle during dynamic contraction of the upper limb in patients with chronic neck pain

The purpose of this study was to compare average muscle fiber conduction velocity (CV) and its changes over time in the upper trapezius muscle during a repetitive upper limb task in people with chronic neck pain and in healthy controls. Surface EMG signals were detected bilaterally from the upper trapezius muscle of 19 patients and nine healthy controls using linear adhesive arrays of four electrodes. Subjects were asked to tap their hands in a cyclic manner between targets positioned mid-thigh and 120 degrees of shoulder flexion, to the beat of a metronome set at 88 beats/min for up to 5 min. Muscle fiber CV and instantaneous mean power spectral frequency were estimated for each cycle at the time instant corresponding to 90 degrees of shoulder flexion. Average muscle fiber CV of the upper trapezius muscle was higher in people with chronic neck pain (mean +/- SE, 4.8 +/- 0.1 m/s) than in control subjects (4.4 +/- 0.1 m/s; P

Widespread sensory hypersensitivity is a feature of chronic whiplash-associated disorder but not chronic idiopathic neck pain

Objectives: To investigate sensory changes present in patients with chronic whiplash-associated disorders and chronic idiopathic neck pain using a variety of quantitative sensory tests to better understand the pain processing mechanisms underlying persistent symptoms. Methods: A case control study was used with 29 subjects with chronic whiplash-associated disorders, 20 subjects with chronic idiopathic neck pain, and 20 pain-free volunteers. Pressure pain thresholds were measured over the articular pillars of C2-C3, C5-C6, the median, radial, and ulnar nerve trunks in the arm and over a remote site, the muscle belly of tibialis anterior. Heat pain thresholds, cold pain thresholds, and von Frey hair sensibility were measured over the cervical spine, tibialis anterior, and deltoid insertion. Anxiety was measured with the Short-Form of the Spielberger State Anxiety Inventory. Results: Pressure pain thresholds were decreased over cervical spine sites in both subject groups when compared with controls (P < 0.05). In the chronic whiplash-associated disorders group, pressure pain thresholds were also decreased over the tibialis anterior, median, and radial nerve trunks (P < 0.001). Heat pain thresholds were decreased and cold pain thresholds increased at all sites (P < 0.03). No differences in heat pain thresholds or cold pain thresholds were evident in the idiopathic neck pain group at any site compared with the control group (P > 0.27). No abnormalities in von Frey hair sensibility were evident in either neck pain group (P > 0.28). Discussion: Both chronic whiplash-associated disorders and idiopathic neck pain groups were characterized by mechanical hyperalgesia over the cervical spine. Whiplash subjects showed additional widespread hypersensitivity to mechanical pressure and thermal stimuli, which was independent of state anxiety and may represent changes in central pain processing mechanisms. This may have implications for future treatment approaches.

An endurance-strength training regime is effective in reducing myoelectric manifestations of cervical flexor muscle fatigue in females with chronic neck pain

Objective: The purpose of this study was to investigate whether an endurance-strength training program is effective in reducing myoelectric manifestations of sternocleidomastoid (SCM) and anterior scalene (AS) muscle fatigue which have been found to be greater in people with chronic neck pain. Methods: Fifty-eight female patients with chronic non-severe neck pain were randomized into one of two 6-week exercise intervention groups: an endurance-strength training regime for the cervical flexor muscles or a referent exercise intervention involving low load retraining of the cranio-cervical flexor muscles. The primary outcomes were a change in maximum voluntary contraction (MVC) force and change of the initial value and rate of change of the mean frequency, average rectified value and conduction velocity detected from the SCM and AS muscles during sub-maximal isometric cervical flexion contractions at 50, 25 and 10% MVC. Results: At the 7th week follow-up assessment, the endurance-strength training group revealed a significant increase in MVC force and a reduction in the estimates of the initial value and rate of change of the mean frequency for both the SCM and AS muscles (P < 0.05). Both exercise groups reported a reduced average intensity of neck pain and reduced neck disability index score (P < 0.05). Conclusions: An endurance-strength exercise regime for the cervical flexor muscles is effective in reducing myoelectric manifestations of superficial cervical flexor muscle fatigue as well as increasing cervical flexion strength in a group of patients with chronic non-severe neck pain. Significance: Provision of load to challenge the neck flexor muscles is required to reduce the fatigability of the SCM and AS muscles in people with neck pain. Improvements in cervical muscle strength and reduced fatigability may be responsible for the reported efficacy with this type of exercise program. (c) 2006 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All fights reserved.

Head repositioning accuracy in patients with neck pain and asymptomatic subjects: concurrent validity, influence of motion speed, motion direction and target distance

Background: Cervicocephalic kinesthetic deficiencies have been demonstrated in patients with chronic neck pain (NP). On the other hand, authors emphasized the use of different motion speeds for assessing functional impairment of the cervical spine. Purpose: The objectives of this study were (1) to investigate the head repositioning accuracy in NP patients and control subjects and (2) to assess the influence of target distance, motion speed, motion direction and pain. Materials and methods: Seventy-one subjects (36 healthy subjects and 35 NP patients; age 30–55 years) performed the head repositioning test (HRT) at two different speeds for horizontal and vertical movements and at two different distances. For each condition, six consecutive trials were sampled. Results: The study showed the validity and reproducibility of the HRT, confirming a dysfunctional threshold of 4.5°. Normative values of head repositioning error up to 3.6° and 7.1° were identified for healthy and NP subjects, respectively. A distance of 180 cm from the target and a natural motion speed increased HRT accuracy. Repositioning after extension movement showed a significantly larger error in both groups. Intensity, duration of pain as well as pain level did not significantly alter head repositioning error. Conclusions: The assessment of proprioceptive performance in healthy and NP subjects allowed the validation of the HRT. The HRT is a simple, not expensive and fast test, easily implementable in daily practice to assess and monitor treatment and evolution of proprioceptive cervical deficits.

The burden of neck pain: its meaning for persons with neck pain and healthcare providers, explored by concept mapping

PURPOSE: To empirically define the concept of burden of neck pain. The lack of a clear understanding of this construct from the perspective of persons with neck pain and care providers hampers adequate measurement of this burden. An additional aim was to compare the conceptual model obtained with the frequently used Neck Disability Index (NDI). METHODS: Concept mapping, combining qualitative (nominal group technique and group consensus) and quantitative research methods (cluster analysis and multidimensional scaling), was applied to groups of persons with neck pain (n = 3) and professionals treating persons with neck pain (n = 2). Group members generated statements, which were organized into concept maps. Group members achieved consensus about the number and description of domains and the researchers then generated an overall mind map covering the full breadth of the burden of neck pain. RESULTS: Concept mapping revealed 12 domains of burden of neck pain: impaired mobility neck, neck pain, fatigue/concentration, physical complaints, psychological aspects/consequences, activities of daily living, social participation, financial consequences, difficult to treat/difficult to diagnose, difference of opinion with care providers, incomprehension by social environment, and how person with neck pain deal with complaints. All ten items of the NDI could be linked to the mind map, but the NDI measures only part of the burden of neck pain. CONCLUSION: This study revealed the relevant domains for the burden of neck pain from the viewpoints of persons with neck pain and their care providers. These results can guide the identification of existing measurements instruments for each domain or the development of new ones to measure the burden of neck pain.

Interaction of psychosocial risk factors explain increased neck problems among female office workers

This study investigated the relationship between psychosocial risk factors and (1) neck symptoms and (2) neck pain and disability as measured by the neck disability index (NDI). Female office workers employed in local private and public organizations were invited to participate, with 333 completing a questionnaire. Data were collected on various risk factors including age, negative affectivity, history of previous neck trauma, physical work environment, and task demands. Sixty-one percent of the sample reported neck symptoms lasting greater than 8 days in the last 12 months. The mean NDI of the sample was 15.5 out of 100, indicating mild neck pain and disability. In a hierarchical multivariate logistic regression, low supervisor support was the only psychosocial risk factor identified with the presence of neck symptoms. Similarly, low supervisor support was the only factor associated with the score on the NDI. These associations remained after adjustment for potential confounders of age, negative affectivity, and physical risk factors. The interaction of job demands, decision authority, and supervisor support was significantly associated with the NDI in the final model and this association increased when those with previous trauma were excluded. Interestingly, and somewhat contrary to initial expectations, as job demands increased, high decision authority had an increasing effect on the NDI when supervisor support was low.