Post-traumatic myofascial pain of the head and neck

Headache production during physical examination in patients with and without headache attributed to a whiplash injury: A case-control study

BACKGROUND

Provocation of headache on physical examination of the neck may reflect a role of cervical structures in the presence of acute whiplash-associated headache (WAH).

OBJECTIVE

To determine differences in headache provocation during physical tests in people with and without WAH after a whiplash injury.

DESIGN

Case-control study.

METHODS

Forty-seven people with acute whiplash-associated disorders participated, 28 with WAH. Passive accessory intervertebral movement over the tubercle of C1, the spinous processes of C2-C3 and facet joints of C0-C4, the flexion-rotation test (FRT), manual palpation of cranio-cervical muscles and the upper limb neurodynamic test + cranio-cervical flexion were assessed bilaterally twice by a blinded examiner; headache provocation was determined. Cohen's kappa and Chi-squared were determined to evaluate the intra-rater reliability of test results and differences between groups, respectively. A logistic regression model was also performed.

RESULTS

Intra-rater reliability of headache provocation was good or excellent for most tests. Significant differences between groups were found with higher positive tests in WAH for the assessment of C2 (68%), the most painful side of C0-C1 (57%), C1-C2 (75%) and C2-C3 (53%), most (79%) and least (25%) restricted sides of the FRT, and manual palpation of the most painful side for the trapezius (53%), masseter (50%) and temporalis (46%) muscles. Provocation of headache during the assessment of C2 and C1-C2 on the most painful side demonstrated the highest association with WAH.

CONCLUSION

Mechanical provocation of headache is more frequent in people with WAH than in those without headache soon after a whiplash injury.

The refined biomimetic NeuroDigm GEL™ model of neuropathic pain in a mature rat

Background: Many humans suffering with chronic neuropathic pain have no objective evidence of an etiological lesion or disease. Frequently their persistent pain occurs after the healing of a soft tissue injury. Based on clinical observations over time, our hypothesis was that after an injury in mammals the process of tissue repair could cause chronic neural pain. Our objectives were to create the delayed onset of neuropathic pain in rats with minimal nerve trauma using a physiologic hydrogel, and characterize the rats' responses to known analgesics and a targeted biologic. Methods: In mature male Sprague Dawley rats (age 9.5 months) a percutaneous implant of tissue-derived hydrogel was placed in the musculofascial tunnel of the distal tibial nerve. Subcutaneous morphine (3 mg/kg), celecoxib (10 mg/kg), gabapentin (25 mg/kg) and duloxetine (10 mg/kg) were each screened in the model three times each over 5 months after pain behaviors developed. Sham and control groups were used in all screenings. A pilot study followed in which recombinant human erythropoietin (200 units) was injected by the GEL™ neural procedure site. Results: The GEL group gradually developed mechanical hypersensitivity lasting months. Morphine, initially effective, had less analgesia over time. Celecoxib produced no analgesia, while gabapentin and duloxetine at low doses demonstrated profound analgesia at all times tested. The injected erythropoietin markedly decreased bilateral pain behavior that had been present for over 4 months, p ≤ 0.001. Histology of the GEL group tibial nerve revealed a site of focal neural remodeling, with neural regeneration, as found in nerve biopsies of patients with neuropathic pain. Conclusion: The refined NeuroDigm GEL™ model induces a neural response resulting in robust neuropathic pain behavior. The analgesic responses in this model reflect known responses of humans with neuropathic pain. The targeted recombinant human erythropoietin at the ectopic neural lesion appears to alleviate the persistent pain behavior in the GEL™ model rodents.

The refined biomimetic NeuroDigm GEL™ Model of neuropathic pain in the mature rat

Background:Many humans suffering with chronic pain have no clinical evidence of a lesion or disease. They are managed with a morass of drugs and invasive procedures. Opiates usually become less effective over time. In many, their persistent pain occurs after the healing of a soft tissue injury. Current animal models of neuropathic pain typically create direct neural damage with open surgeries using ligatures, neurectomies, chemicals or other forms of deliberate trauma. However, we have observed clinically that after an injury in humans, the naturally occurring process of tissue repair can cause chronic neural pain.Methods:We demonstrate how the refined biomimetic NeuroDigm GEL™ Model, in the mature male rat, gradually induces neuropathic pain behavior with a nonsurgical percutaneous implant of tissue-derived hydrogel in the musculo-fascial tunnel of the distal tibial nerve. Morphine, Celecoxib, Gabapentin and Duloxetine were each screened in the model three times each over 5 months after pain behaviors developed. A pilot study followed in which recombinant human erythropoietin was applied to the GEL neural procedure site.Results:The GEL Model gradually developed neuropathic pain behavior lasting months. Morphine, initially effective, had less analgesia over time. Celecoxib produced no analgesia, while gabapentin and duloxetine at low doses had profound analgesia at all times tested. The injected erythropoietin markedly decreased bilateral pain behavior that had been present for over 4 months. Histology revealed a site of focal neural remodeling, with neural regeneration, as in human biopsies.Conclusion:The refined NeuroDigm GEL™ Model induces localized neural remodeling resulting in robust neuropathic pain behavior. The analgesics responses in this model reflect known responses of humans with neuropathic pain. The targeted recombinant human erythropoietin appears to heal the ectopic focal neural site, as demonstrated by the extinguishing of neuropathic pain behavior present for over 4 months.

Treatment of cervicogenic headache with cervical epidural steroid injection

Cervicogenic headache (CGH) is defined as referred pain from various cervical structures innervated by the upper three cervical spinal nerves. Such structures are potential pain generators, and include the atlanto-occipital joint, atlantoaxial joint, C2-3 zygapophysial joint, C2-3 intervertebral disc, cervical myofascial trigger points, as well as the cervical spinal nerves. Various interventional techniques, including cervical epidural steroid injection (CESI), have been proposed to treat this disorder. And while steroids administered by cervical epidural injection have been used in clinical practice to provide anti-inflammatory and analgesic effects that may alleviate pain in patients with CGH, the use of CESI in the diagnosis and treatment of CGH remains controversial. This article describes the neuroanatomy, neurophysiology, and classification of CGH as well as a review of the available literature describing CESI as treatment for this debilitating condition.

Persistent orofacial muscle pain

The pathophysiology of persistent orofacial myalgia has been the centre of much controversy. In this article we suggest a novel descriptive term; 'persistent orofacial muscle pain' (POMP) and review current evidence that supports the hypothesis that the induction of POMP involves the interplay between a peripheral nociceptive source in muscle, a faulty central nervous system component and decreased coping ability. In this context it is widely accepted that a complex interaction of variable intrinsic and extrinsic factors act to induce POMP and dysfunction.