Ashley Dean Smith

Minimizing the source of nociception and its concurrent effect on sensory hypersensitivity: an exploratory study in chronic whiplash patients.

BackgroundThe cervical zygapophyseal joints may be a primary source of pain in up to 60% of individuals with chronic whiplash associated disorders (WAD) and may be a contributing factor for peripheral and centrally mediated pain (sensory hypersensitivity). Sensory hypersensitivity has been associated with a poor prognosis. The purpose of the study was to determine if there is a change in measures indicative of sensory hypersensitivity in patients with chronic WAD grade II following a medial branch block (MBB) procedure in the cervical spine.MethodsMeasures of sensory hypersensitivity were taken via quantitative sensory testing (QST) consisting of pressure pain thresholds (PPTs) and cold pain thresholds (CPTs). In patients with chronic WAD (n = 18), the measures were taken at three sites bilaterally, pre- and post- MBB. Reduced pain thresholds at remote sites have been considered an indicator of central hypersensitivity. A healthy age and gender matched comparison group (n = 18) was measured at baseline. An independent t-test was applied to determine if there were any significant differences between the WAD and normative comparison groups at baseline with respect to cold pain and pressure pain thresholds. A dependent t-test was used to determine whether there were any significant differences between the pre and post intervention cold pain and pressure pain thresholds in the patients with chronic WAD.ResultsAt baseline, PPTs were decreased at all three sites in the WAD group (p < 0.001). Cold pain thresholds were increased in the cervical spine in the WAD group (p < 0.001). Post-MBB, the WAD group showed significant increases in PPTs at all sites (p < 0.05), and significant decreases in CPTs at the cervical spine (p < 0.001).ConclusionsThe patients with chronic WAD showed evidence of widespread sensory hypersensitivity to mechanical and thermal stimuli. The WAD group revealed decreased sensory hypersensitivity following a decrease in their primary source of pain stemming from the cervical zygapophyseal joints.

Cervical Radiofrequency Neurotomy Reduces Central Hyperexcitability and Improves Neck Movement in Individuals with Chronic Whiplash

OBJECTIVE This study aims to determine if cervical medial branch radiofrequency neurotomy reduces psychophysical indicators of augmented central pain processing and improves motor function in individuals with chronic whiplash symptoms. DESIGN Prospective observational study of consecutive patients with healthy control comparison. SETTING Tertiary spinal intervention centre in Calgary, Alberta, Canada. SUBJECTS Fifty-three individuals with chronic whiplash associated disorder symptoms (Grade 2); 30 healthy controls. METHODS Measures were made at four time points: two prior to radiofrequency neurotomy, and 1- and 3-months post-radiofrequency neurotomy. Measures included: comprehensive quantitative sensory testing (including brachial plexus provocation test), nociceptive flexion reflex, and motor function (cervical range of movement, superficial neck flexor activity during the craniocervical flexion test). Self-report pain and disability measures were also collected. One-way repeated measures analysis of variance and Friedmans tests were performed to investigate the effect of time on the earlier measures. Differences between the whiplash and healthy control groups were investigated with two-tailed independent samples t-test or Mann-Whitney tests. RESULTS Following cervical radiofrequency neurotomy, there were significant early (within 1 month) and sustained (3 months) improvements in pain, disability, local and widespread hyperalgesia to pressure and thermal stimuli, nociceptive flexor reflex threshold, and brachial plexus provocation test responses as well as increased neck range of motion (all P < 0.0001). A nonsignificant trend for reduced muscle activity with the craniocervical flexion test (P > 0.13) was measured. CONCLUSIONS Attenuation of psychophysical measures of augmented central pain processing and improved cervical movement imply that these processes are maintained by peripheral nociceptive input.

A comparison of physical and psychological features of responders and non-responders to cervical facet blocks in chronic whiplash

BackgroundCervical facet block (FB) procedures are often used as a diagnostic precursor to radiofrequency neurotomies (RFN) in the management of chronic whiplash associated disorders (WAD). Some individuals will respond to the FB procedures and others will not respond. Such responders and non-responders provided a sample of convenience to question whether there were differences in their physical and psychological features. This information may inform future predictive studies and ultimately the clinical selection of patients for FB procedures.MethodsThis cross-sectional study involved 58 individuals with chronic WAD who responded to cervical FB procedures (WAD_R); 32 who did not respond (WAD_NR) and 30 Healthy Controls (HC)s. Measures included: quantitative sensory tests (pressure; thermal pain thresholds; brachial plexus provocation test); nociceptive flexion reflex (NFR); motor function (cervical range of movement (ROM); activity of the superficial neck flexors during the cranio-cervical flexion test (CCFT). Self-reported measures were gained from the following questionnaires: neuropathic pain (s-LANSS); psychological distress (General Health Questionnaire-28), post-traumatic stress (PDS) and pain catastrophization (PCS). Individuals with chronic whiplash attended the laboratory once the effects of the blocks had abated and symptoms had returned.ResultsFollowing FB procedures, both WAD groups demonstrated generalized hypersensitivity to all sensory tests, decreased neck ROM and increased superficial muscle activity with the CCFT compared to controls (p < 0.05). There were no significant differences between WAD groups (all p > 0.05). Both WAD groups demonstrated psychological distress (GHQ-28; p < 0.05), moderate post-traumatic stress symptoms and pain catastrophization. The WAD_NR group also demonstrated increased medication intake and elevated PCS scores compared to the WAD_R group (p < 0.05).ConclusionsChronic WAD responders and non-responders to FB procedures demonstrate a similar presentation of sensory disturbance, motor dysfunction and psychological distress. Higher levels of pain catastrophization and greater medication intake were the only factors found to differentiate these groups.

Intrarater and interrater reliability of select clinical tests in patients referred for diagnostic facet joint blocks in the cervical spine

OBJECTIVE To measure the intra- and interrater reliability of select standardized clinical tests used for the assessment of patients with axial neck pain referred for diagnostic facet joint blocks. DESIGN Single-group, repeated-measures study. SETTING Tertiary interventional pain management center. PARTICIPANTS Consecutive patients with persistent neck pain, referred to a tertiary interventional pain management center, were approached to participate. Fifty-six patients consented to participate in the study. INTERVENTIONS Subjects underwent a standardized clinical testing protocol, performed by 2 physiotherapists, before receiving diagnostic facet joint blocks. Subjects were examined twice by 1 assessor for the determination of the intrarater reliability of the testing protocol, and again by a second assessor for determination of interrater reliability. MAIN OUTCOME MEASURES Intraclass correlation coefficients (ICCs), kappa coefficients, and 95% confidence intervals were calculated to determine the intra- and interrater reliability for cervical range of motion (ROM; 6 directions), extension-rotation (ER) test, manual spinal examination (MSE), and palpation for paraspinal tenderness (PST) from C2 through C7. RESULTS For intrarater reliability, kappa coefficients ranged from .51 to .88 for the ER test, MSE, and PST, and ICCs ranged from .91 to .97 for ROM. For interrater reliability, kappa coefficients ranged from .74 to .96 for the ER test, MSE, and PST, and ICCs ranged from .90 to .95 for ROM. CONCLUSIONS The standardized clinical tests exhibited moderate to substantial reliability in patients with axial neck pain referred for diagnostic facet joint blocks. The data justify the incorporation of these tests into a clinical prediction model to screen patients before referral for diagnostic facet blocks.

Derivation of a clinical decision guide in the diagnosis of cervical facet joint pain

OBJECTIVE To derive a clinical decision guide (CDG) to identify patients best suited for cervical diagnostic facet joint blocks. DESIGN Prospective cohort study. SETTING Pain management center. PARTICIPANTS Consecutive patients with neck pain (N=125) referred to an interventional pain management center were approached to participate. INTERVENTIONS Subjects underwent a standardized testing protocol, performed by a physiotherapist, prior to receiving diagnostic facet joint blocks. All subjects received the reference standard diagnostic facet joint block protocol, namely controlled medial branch blocks (MBBs). The physicians performing the MBBs were blinded to the local anesthetic used and findings of the clinical tests. MAIN OUTCOME MEASURES Multivariate regression analyses were performed in the derivation of the CDGs. Sensitivity, specificity, positive and negative likelihood ratios, and 95% confidence intervals (CIs) were calculated for the index tests and CDGs. RESULTS A CDG involving the findings of the manual spinal examination (MSE), palpation for segmental tenderness (PST), and extension-rotation (ER) test demonstrated a specificity of 84% (95% CI, 77-90) and a positive likelihood ratio of 4.94 (95% CI, 2.8-8.2). Sensitivity of the PST and MSE were 94% (95% CI, 90-98) and 92% (95% CI, 88-97), respectively. Negative findings on the PST were associated with a negative likelihood ratio of .08 (95% CI, .03-.24). CONCLUSIONS MSE, PST, and ER may be useful tests in identifying patients suitable for diagnostic facet joint blocks. Further research is needed to validate the CDGs prior to their routine use in clinical practice.

Low Pain Catastrophization and Disability Predict Successful Outcome to Radiofrequency Neurotomy in Individuals with Chronic Whiplash

Physical and psychological symptoms of individuals with chronic whiplash‐associated disorders (WAD) are modulated by successful treatment with cervical radiofrequency neurotomy (cRFN). However, not all individuals respond to cRFN, and it is unknown which clinical features predict successful response to cRFN.

The influence of isometric exercise on endogenous pain modulation: comparing exercise-induced hypoalgesia and offset analgesia in young, healthy adults

Abstract Background and aims Impairment of endogenous analgesia has been associated with the development, maintenance and persistence of pain. Endogenous analgesia can be evaluated using exercise-induced hypoalgesia (EIH) and offset analgesia (OffA) paradigms, which measure temporal filtering of sensory information. It is not clear if these paradigms are underpinned by common mechanisms, as EIH and OffA have not previously been directly compared. A further understanding of the processes responsible for these clinically relevant phenomena may have future diagnostic and therapeutic utility in management of individuals with persistent pain conditions. The primary aim of this study was to investigate if there is a correlation between the magnitudes of EIH and OffA. The secondary aim of the study was to examine whether exercise influences OffA. Methods Thirty-six healthy, pain-free participants were recruited. EIH was evaluated using pressure pain thresholds (PPT) and pain ratings to suprathreshold pressure stimuli over tibialis anterior and the cervical spine. OffA evaluation utilised a three-step protocol, whereby individualised heat pain thermal stimuli [Numerical Rating Scale (NRS)=50/100] were applied (T1), before increasing 1 °C (T2), followed by 1 °C reduction (T3). The magnitude of OffA was calculated as the percentage reduction in the NRS from T2 to T3. PPT/suprathreshold pain ratings and OffA measures were recorded, before and after 5 min of isometric quadriceps exercise performed at 20–25% maximum voluntary contraction (MVC); and following a 15 min rest period. Data were analysed using repeated measures (RM) ANCOVA and correlational analyses. Results There was no correlation between EIH measures (PPTs or pain ratings to suprathreshold pressure stimuli over tibialis anterior or the cervical spine) and OffA (p>0.11 for all). OffA was induced and not modulated by exercise (p=0.28). Conclusions Five minutes of 20–25% MVC lower limb isometric exercise provided non-pharmacological pain modulation in young, active adults. Magnitude of EIH was not correlated with that of OffA, and exercise did not influence magnitude of OffA. Implications These results suggest that in young, pain-free individuals, separate testing of these two paradigms is required to comprehensively evaluate efficacy of endogenous analgesia. If these results are replicated in patient populations, alternative or complementary methods to exercise interventions may be required to modulate impaired OffA.

Whiplash associated disorders: A prospective investigation of the effects of cervical medial branch radiofrequency neurotomy on sensory, motor and psychological Features

............................................................................................................................................................ 2 DECLARATION BY AUTHOR ............................................................................................................................ 5 PUBLICATIONS DURING CANDIDATURE ..................................................................................................... 6 PEER REVIEWED JOURNALS: FIRST AUTHOR ...............................................................................................6 SUBMITTED FOR PUBLICATION: FIRST AUTHOR...........................................................................................6 CONFERENCE ABSTRACTS: FIRST AUTHOR .................................................................................................6 CONFERENCE PUBLICATIONS: CO-AUTHOR .................................................................................................9 PUBLICATIONS INCLUDED IN THIS THESIS ............................................................................................... 9 CONTRIBUTIONS BY OTHERS TO THE THESIS ........................................................................................ 15 STATEMENT OF PARTS OF THE THESIS SUBMITTED TO QUALIFY FOR THE AWARD OF ANOTHER DEGREE ........................................................................................................................................... 15 ACKNOWLEDGEMENTS .................................................................................................................................. 16