A critical appraisal of the evidence for botulinum toxin type A in the treatment for cervico-thoracic myofascial pain syndrome

Management of neck pain and associated disorders: A clinical practice guideline from the Ontario Protocol for Traffic Injury Management (OPTIMa) Collaboration

PURPOSE

To develop an evidence-based guideline for the management of grades I-III neck pain and associated disorders (NAD).

METHODS

This guideline is based on recent systematic reviews of high-quality studies. A multidisciplinary expert panel considered the evidence of effectiveness, safety, cost-effectiveness, societal and ethical values, and patient experiences (obtained from qualitative research) when formulating recommendations. Target audience includes clinicians; target population is adults with grades I-III NAD <6 months duration.

RECOMMENDATION 1

Clinicians should rule out major structural or other pathologies as the cause of NAD. Once major pathology has been ruled out, clinicians should classify NAD as grade I, II, or III.

RECOMMENDATION 2

Clinicians should assess prognostic factors for delayed recovery from NAD.

RECOMMENDATION 3

Clinicians should educate and reassure patients about the benign and self-limited nature of the typical course of NAD grades I-III and the importance of maintaining activity and movement. Patients with worsening symptoms and those who develop new physical or psychological symptoms should be referred to a physician for further evaluation at any time during their care.

RECOMMENDATION 4

For NAD grades I-II ≤3 months duration, clinicians may consider structured patient education in combination with: range of motion exercise, multimodal care (range of motion exercise with manipulation or mobilization), or muscle relaxants. In view of evidence of no effectiveness, clinicians should not offer structured patient education alone, strain-counterstrain therapy, relaxation massage, cervical collar, electroacupuncture, electrotherapy, or clinic-based heat.

RECOMMENDATION 5

For NAD grades I-II >3 months duration, clinicians may consider structured patient education in combination with: range of motion and strengthening exercises, qigong, yoga, multimodal care (exercise with manipulation or mobilization), clinical massage, low-level laser therapy, or non-steroidal anti-inflammatory drugs. In view of evidence of no effectiveness, clinicians should not offer strengthening exercises alone, strain-counterstrain therapy, relaxation massage, relaxation therapy for pain or disability, electrotherapy, shortwave diathermy, clinic-based heat, electroacupuncture, or botulinum toxin injections.

RECOMMENDATION 6

For NAD grade III ≤3 months duration, clinicians may consider supervised strengthening exercises in addition to structured patient education. In view of evidence of no effectiveness, clinicians should not offer structured patient education alone, cervical collar, low-level laser therapy, or traction. RECOMMENDATION 7: For NAD grade III >3 months duration, clinicians should not offer a cervical collar. Patients who continue to experience neurological signs and disability more than 3 months after injury should be referred to a physician for investigation and management. RECOMMENDATION 8: Clinicians should reassess the patient at every visit to determine if additional care is necessary, the condition is worsening, or the patient has recovered. Patients reporting significant recovery should be discharged.

Current status and future directions of botulinum neurotoxins for targeting pain processing

Current evidence suggests that botulinum neurotoxins (BoNTs) A1 and B1, given locally into peripheral tissues such as skin, muscles, and joints, alter nociceptive processing otherwise initiated by inflammation or nerve injury in animal models and humans. Recent data indicate that such locally delivered BoNTs exert not only local action on sensory afferent terminals but undergo transport to central afferent cell bodies (dorsal root ganglia) and spinal dorsal horn terminals, where they cleave SNAREs and block transmitter release. Increasing evidence supports the possibility of a trans-synaptic movement to alter postsynaptic function in neuronal and possibly non-neuronal (glial) cells. The vast majority of these studies have been conducted on BoNT/A1 and BoNT/B1, the only two pharmaceutically developed variants. However, now over 40 different subtypes of botulinum neurotoxins (BoNTs) have been identified. By combining our existing and rapidly growing understanding of BoNT/A1 and /B1 in altering nociceptive processing with explorations of the specific characteristics of the various toxins from this family, we may be able to discover or design novel, effective, and long-lasting pain therapeutics. This review will focus on our current understanding of the molecular mechanisms whereby BoNTs alter pain processing, and future directions in the development of these agents as pain therapeutics.