Bogdan P. Radanov

Evidence for spinal cord hypersensitivity in chronic pain after whiplash injury and in fibromyalgia

&NA; Patients with chronic pain after whiplash injury and fibromyalgia patients display exaggerated pain after sensory stimulation. Because evident tissue damage is usually lacking, this exaggerated pain perception could be explained by hyperexcitability of the central nervous system. The nociceptive withdrawal reflex (a spinal reflex) may be used to study the excitability state of spinal cord neurons. We tested the hypothesis that patients with chronic whiplash pain and fibromyalgia display facilitated withdrawal reflex and therefore spinal cord hypersensitivity. Three groups were studied: whiplash (n=27), fibromyalgia (n=22) and healthy controls (n=29). Two types of transcutaneous electrical stimulation of the sural nerve were applied: single stimulus and five repeated stimuli at 2 Hz. Electromyography was recorded from the biceps femoris muscle. The main outcome measurement was the minimum current intensity eliciting a spinal reflex (reflex threshold). Reflex thresholds were significantly lower in the whiplash compared with the control group, after both single (P=0.024) and repeated (P=0.035) stimulation. The same was observed for the fibromyalgia group, after both stimulation modalities (P=0.001 and 0.046, respectively). We provide evidence for spinal cord hyperexcitability in patients with chronic pain after whiplash injury and in fibromyalgia patients. This can cause exaggerated pain following low intensity nociceptive or innocuous peripheral stimulation. Spinal hypersensitivity may explain, at least in part, pain in the absence of detectable tissue damage.

Long-term outcome after whiplash injury. A 2-year follow-up considering features of injury mechanism and somatic, radiologic, and psychosocial findings

With the increased incidence of whiplash injury following the introduction of compulsory car seat belts, a large number of reports have dealt with the aftermath of this condition. Previous studies, however, focused on somatic symptoms on the one hand or considered only psychological or neuropsychological variables on the other hand, often in loosely defined or selected groups of patients. No study so far has analyzed the long-term outcome in a nonselected group of patients using a clear injury definition considering patient history; somatic, radiologic, and neuropsychological findings; and features of the injury mechanisms assessed soon after trauma and during follow-up. the present investigation was designed to assess these combined factors. According to a strict definition of whiplash injury, we assessed a consecutive nonselected sample of 117 patients with recent injury who had similar sociocultural and educational backgrounds. The patients had been in automobile crashes and were all equally covered by accident insurance according to the country-wide scheme. Initial examination was performed 7.2 +/- 4.2 days after trauma, and follow-up examinations 3, 6, 12, and 24 months later. At baseline, features of injury mechanism, subjective complaints, and different aspects of patient history were documented and cervical spine X rays performed. At all examinations patients underwent neurologic examination and cognitive and psychosocial factor assessment. At 2 years, patients were divided into symptomatic and asymptomatic groups and then compared with regard to the initial findings. In addition, symptomatic patients who were disabled at the 2-year follow-up examination and symptomatic patients not disabled (that is, they were able to work at the pretraumatic level) were compared regarding initial and 2-year findings. At 2 years, 18% of patients still had injury-related symptoms. With regard to baseline findings the following significant differences were found: Symptomatic patients were older, had higher incidence of rotated or inclined head position at the time of impact, had higher prevalence of pretraumatic headache, showed higher intensity of initial neck pain and headache, complained of a greater number of symptoms, had a higher incidence of symptoms of radicular deficit and higher average scores on a multiple symptom analysis, and displayed more degenerative signs (osteoarthrosis) on X ray. In addition, symptomatic patients scored higher with regard to impaired well-being and performed worse on tasks of attentional functioning and showed more concern with regard to long-term suffering and disability.(ABSTRACT TRUNCATED AT 400 WORDS)

Central hypersensitivity in chronic pain after whiplash injury.

ObjectiveThe mechanisms underlying chronic pain after whiplash injury are usually unclear. Injuries may cause sensitization of spinal cord neurons in animals (central hypersensitivity), which results in increased responsiveness to peripheral stimuli. In humans, the responsiveness of the central nervous system to peripheral stimulation may be explored by applying sensory tests to healthy tissues. The hypotheses of this study were: (1) chronic whiplash pain is associated with central hypersensitivity; (2) central hypersensitivity is maintained by nociception arising from the painful or tender muscles in the neck. DesignComparison of patients with healthy controls. SettingPain clinic and laboratory for pain research, university hospital. PatientsFourteen patients with chronic neck pain after whiplash injury (car accident) and 14 healthy volunteers. Outcome MeasuresPain thresholds to: single electrical stimulus (intramuscular), repeated electrical stimulation (intramuscular and transcutaneous), and heat (transcutaneous). Each threshold was measured at neck and lower limb, before and after local anesthesia of the painful and tender muscles of the neck. ResultsThe whiplash group had significantly lower pain thresholds for all tests, except heat, at both neck and lower limb. Local anesthesia of the painful and tender points affected neither intensity of neck pain nor pain thresholds. ConclusionsThe authors found a hypersensitivity to peripheral stimulation in whiplash patients. Hypersensitivity was observed after cutaneous and muscular stimulation, at both neck and lower limb. Because hypersensitivity was observed in healthy tissues, it resulted from alterations in the central processing of sensory stimuli (central hypersensitivity). Central hypersensitivity was not dependent on a nociceptive input arising from the painful and tender muscles.

Presenting symptoms and signs after whiplash injury The influence of accident mechanisms

Objective: To assess the relationship between accident mechanisms and initial findings after whiplash injury. Design: Cohort study. Setting: Outpatient department, Department of Neurology, University of Berne, Switzerland. Patients: A population-based sample of 137 consecutive patients referred by primary care physicians. Fractures or dislocations of the cervical spine, head trauma, and preexisting neurologic disorders were exclusion criteria. Main outcome measures: Patients were interviewed and examined within 7.2 days (SD, 3.9 days) after trauma. Analyzed accident features were position in the car, use of seat belt, head restraint and its point of head contact, damage to seat, head position and state of preparedness at the moment of impact, and type of collision. Analyzed symptoms were intensity and onset delay of post-traumatic head and neck pain; pain in the shoulders, back, and anterior neck; symptoms of neurologic dysfunction according to presumed origin–cranial nerve or brainstem, radicular or myelopathic; and a score of multiple symptoms. Analyzed signs were neck muscle tenderness and restricted neck movement, and signs of cranial nerve, brainstem, or radicular dysfunction. Results: Passenger position in the car, use of seat belt, and the presence of a head restraint showed no significant relationship with findings. Rotated or inclined head position at the moment of impact was associated with a higher frequency of multiple symptoms (p = 0.045 and 0.008) with more severe symptoms and signs of musculoligamental cervical strain (p = 0.048 and 0.038) and of neural, particularly radicular (p = 0.031 and 0.019), damage. Unprepared occupants had a higher frequency of multiple symptoms (p = 0.031) and more severe headache (p = 0.046). Rear-end collision was associated with a higher frequency of multiple symptoms (p = 0.006), especially of cranial nerve or brainstem dysfunction (p = 0.00003). Conclusion: Three features of accident mechanisms were associated with more severe symptoms: an unprepared occupant; rear-end collision, with or without subsequent frontal impact; and rotated or inclined head position at the moment of impact.

The effect of accident mechanisms and initial findings on the long-term course of whiplash injury

The aim of this study was to assess the relationships between accident mechanisms as well as initial findings and the long-term course of whiplash injury. A representative sample of 117 consecutive patients referred by primary care physicians was followed-up over 12 months. Fractures or dislocations of the cervical spine, head trauma and pre-existing neurological disorders were exclusion criteria. The interval between the accident and the baseline examination was 7.4 days (SD 4.2 days). Assessment included accident features (e.g. passenger position in the car, head restraint, head position, type of collision), initial symptoms (e.g. intensity and onset of pain, symptoms of neurological dysfunction, multiple symptom score), and signs (restricted neck movement, neurological deficits). At the 1-year examination, patients were divided into an asymptomatic and a symptomatic group and were compared with respect to accident features and baseline findings. Twenty-four percent of patients were still symptomatic after 1 year. Analysing accident mechanisms separately, rotated or inclined head position was the primary feature related to symptom persistence (P=0.005). The symptomatic group scored higher at baseline on the multiple symptom rating (P=0.004) and had a higher incidence of initial headache (P=0.004) and neurological symptoms (P=0.008) together with a higher intensity of headache (P=0.0002) and neck pain (P=0.0009). The following set of initial variables predicted persistence of symptoms at 1 year (logistic regression): intensity of neck pain (P=0.001) and headache (P=0.009), rotated or inclined head position (P=0.02), unpreparedness at the time of impact (P=0.01) and car stationary when hit (P=0.01). In conclusion, accident mechanisms and initial findings suggestive of more severe injury were significantly related to long-term persistence of symptoms after whiplash injury.

Psychosocial stress, cognitive performance and disability after common whiplash

The relationship between psychosocial stress, cognitive performance and disability was assessed in 97 randomly selected common whiplash patients. Patients were investigated early after injury (mean 7.2 days, SD = 3.8) and again at 6 months. Assessment included different aspects of psychosocial stress, negative affectivity, personality traits and attentional functioning. At 6 months six patients (7%) showed partial or complete disability (disabled group) while 91 patients went back to work at pre-injury levels (non-disabled group). However, 26 patients from the latter group at 6 months were still symptomatic. The disabled and non-disabled groups did not differ with respect to psychosocial stress, negative affectivity and personality traits as assessed at baseline. At 6 months no significant differences were found between the disabled group and 26 symptomatic patients from the non-disabled group with respect to any of the assessed factors. The disabled group showed a combination of the following variables as assessed at baseline: greater age, initial neck pain intensity, initial back pain, blurred vision, and anxiety but less dizziness, sensitivity to noise and neurotic or behavioural problems in childhood.

Factors influencing recovery from headache after common whiplash

OBJECTIVE--To assess the relation between pretraumatic and trauma related headache in patients suffering from whiplash. DESIGN--Follow up study of patients examined a mean (SD) of 7.4 (4.2) days after trauma and again at three and six months. SETTING--Patients referred from primary care. SUBJECTS--117 patients (mean age 30.8 (9.5) years. MAIN OUTCOME MEASURES--Prevalence of trauma related headache and the predictive relation by multiple logistic regression between different somatic and psychological variables and trauma related headache at each examination. RESULTS--Prevalence of trauma related headache decreased from 57% to 27%. History of pretraumatic headache proved a significant risk factor for presenting with trauma related headache. A significant relation between trauma related headache and the following variables was found: at seven days the initial wellbeing score, early onset of neck pain, depression scale from the personality inventory, and the initial intensity of neck pain; at three months, intensity of neck pain, and history of pretraumatic headache; and at six months neck pain, pain intensity, and history of pretraumatic headache. CONCLUSIONS--History of pretraumatic headache significantly increases the likelihood of presenting with trauma related headache but only in combination with findings indicative of clinically important injury to the cervical spine.

The nociceptive withdrawal reflex: Normative values of thresholds and reflex receptive fields

Assessments of spinal nociceptive withdrawal reflexes can be used in human research both to evaluate the effect of analgesics and explore pain mechanisms related to sensitization. Before the reflex can be used as a clinical tool, normative values need to be determined in large scale studies. The aim of this study was to determine the reference values of spinal nociceptive reflexes and subjective pain thresholds (to single and repeated stimulation), and of the area of the reflex receptive fields (RRF) in 300 pain‐free volunteers. The influences of gender, age, height, weight, body‐mass index (BMI), body side of testing, depression, anxiety, catastrophizing and parameters of Short‐Form 36 (SF‐36) were analyzed by multiple regressions. The 95% confidence intervals were determined for all the tests as normative values. Age had a statistically and quantitatively significant impact on the subjective pain threshold to single stimuli. The reflex threshold to single stimulus was lower on the dominant compared to the non‐dominant side. Depression had a negative impact on the subjective pain threshold to single stimuli. All the other analyses either did not reveal statistical significance or displayed quantitatively insignificant correlations. In conclusion, normative values of parameters related to the spinal nociceptive reflex were determined. This allows their clinical application for assessing central hyperexcitability in individual patients. The parameters investigated explore different aspects of sensitization processes that are largely independent of demographic characteristics, cognitive and affective factors.

Predicting Recovery from Common Whiplash

The present study aimed to establish criteria for delayed recovery after whiplash injury using a 1-year prospective cohort study. 117 whiplash patients referred from primary care and 16 whiplash patients recruited from the insurance company. At baseline all patients underwent neurological, radiological and psychosocial factors assessment and testing of personality traits, well-being, cognitive ability and cognitive functioning. According to the logistic regression in patients referred from primary care the following initial variables are in significant relationship with poor outcome at 1 year: impaired neck movement, history of pretraumatic headache, history of head trauma, higher age, initial neck pain intensity, initial headache intensity, nervousness score, neuroticism score and test score on focused attention. Employing these variables, correct prediction of outcome at 1 year was found in 88% of patients recruited from the insurance company. Authors conclude that a comprehensive assessment of whiplash patients early after trauma enables physicians to identify patients at risk of delayed recovery.

Long-term outcome in patients with mild traumatic brain injury: a prospective observational study.

BACKGROUND Mild traumatic brain injury (MTBI) is common; up to 37% of adult men have a history of MTBI. Complaints after MTBI are persistent headaches, memory impairment, depressive mood disorders, and disability. The reported short- and long-term outcomes of patients with MTBI have been inconsistent. We have now investigated long-term clinical and neurocognitive outcomes in patients with MTBI (at admission, and after 1 and 10 years). METHODS Patients of a previous study investigating MTBI short-term outcome were prospectively reassessed after ±10 year using the same standardized data entry form and validated questionnaire (Beltztest with Beltz Score [BeSc]) for evaluation of Quality of life (QoL) and neurocognitive outcome (higher scores indicate lower QoL). RESULTS Eighty-six of 176 patients (49%) could be reassessed (n = 75 lost to follow-up; n = 8 second brain trauma; n = 7 death), 10.4 ± 2 years after initial evaluation. Over time, overall BeSc was significantly increased (5.92 ± 10.3 [admission] vs. 10.7 ± 12.8 [1 year] vs. 20.86 ± 17.1 [10 year]; p < 0.0001); only 54 of 86 patients (62.8%) presented with a normal BeSc. Long-term complaints were fatigue, insomnia, and exhaustion. Ten of eighty-six patients (11.6%) had intracranial injury (ICI) and initial BeSc was almost twofold higher in patients with ICI than in patients without ICI (10.0 ± 8.4 vs. 5.3 ± 9.6; p = 0.007). This difference was not seen after 1 year or after 10 years (10.3 ± 11.6 vs. 10.3 ± 10.1 and 21.4 ± 17.3 vs. 16.1 ± 16.4, respectively). Eight of eighty-six patients (9.3%) lost their jobs because of persistent complaints after MTBI. CONCLUSION BeSc deteriorates over time; our data suggest a decline in general health and QoL in a substantial proportion of patients (37.2%) 10 years after MTBI. Patients without ICI appear to have a better long-term outcome with regard to subjective complaints and QoL.