Localized myofascial pain responds better than referring myofascial pain to botulinum toxin injections.

Myofascial pain of the muscles of mastication is a common temporomandibular disorder. Patients unresponsive to conservative treatment modalities pose a therapeutic challenge to the treating clinician. The efficacy of intramuscular botulinum toxin injections for recalcitrant cases is still not well established due to mixed results from clinical trials. The Diagnostic Criteria of Temporomandibular Disorders (DC/TMD) classified chronic muscle pain broadly into a localized pattern (when pain is localized to the site of palpation or the muscle palpated) and a referring pattern (when the pain spreads beyond the boundary of the muscle being palpated). The medical records of 25 consecutive patients treated with botulinum were analysed retrospectively. Significant pain reduction was achieved in 69.2% of the patients with localized myofascial pain and 16.7% of the patients with referring myofascial pain (P=0.015). Seventy-seven per cent of the patients with localized myofascial pain reported using less analgesic throughout the follow-up period, whereas only 25% of the patients with referring myofascial pain (P=0.017). The effects of botulinum toxin in responsive patients subsided after a mean of 3.21 months. Patients with localized myofascial pain benefited from botulinum toxin injections, but patients with referring myofascial pain responded poorly to this treatment.

Antinociceptive effect of botulinum toxin type A on experimental abdominal pain.

Visceral pain, especially in the abdominal region, represents one of the most common types of pain. Its chronic form is usually very hard to treat by conventional analgesic agents and adjuvants. We investigated the antinociceptive effect of botulinum toxin type A (BTX-A) in male Wistar rats in two models of visceral pain: peritonitis induced by intraperitoneal injection of 1% acetic acid and colitis induced by intracolonic instillation of 0.1% capsaicin. Pain was measured as the number of abdominal writhes. Additionally, referred mechanical sensitivity in the ventral abdominal area was evaluated by von Frey test and the extent of spinal c-Fos expression was immunohistochemically examined. BTX-A significantly reduced the number of abdominal writhes in both models of visceral pain after intrathecal application in a dose of 2 U/kg. In the experimental colitis model, BTX-A (2 U/kg) reduced both referred mechanical allodynia and c-Fos expression in the dorsal horn of the spinal cord (S2/S3 segments). In contrast to intrathecal administration, BTX-A (2 U/kg) administered into the cisterna magna had no effect on pain suggesting that the primary site of its action is a spinal cord.

Effect of combination of trigger point injection and stellate ganglion block on non-odontogenic mandibular molar pain referred from masseter muscle: a case report.

We report a case of myofascial pain syndrome (MPS), manifested as nonodontogenic mandibular molar pain referred from the masseter muscle, relieved by a combination of trigger point injection (TPI) and stellate ganglion block (SGB). The patient was a 32-year-old woman who had experienced cold hypersensitivity in the right third mandibular molar 2 months prior to visiting our department. Subsequently, she had visited a family dentist and undergone pulpectomy under local anesthesia. She eventually visited our clinic because there was no marked change in her symptoms. On the first visit, no tooth abnormality was found and the patient was neither anxious nor depressive. Tender points were found in the right masseter and temporal muscles during muscle palpation. Referred pain radiating to the right mandibular molars was observed when pressure was applied to the central portion of the right masseter muscle. As a result, we diagnosed MPS based on evidence of nonodontogenic tooth pain caused by referred pain from the masseter muscle. We performed TPI with 2% lidocaine hydrochloride to the tender point in the masseter muscle. Although the visual analog scale (VAS) pain score dropped from 97 to 36, complete pain relief was not achieved. The TPI was effective for approximately 7 hrs, after which severe throbbing pain returned. The sustained nature of the tooth pain suggested that it was sympathetic nerve-dependent. Subsequently, we performed SGB, resulting in a reduction in the VAS pain score from 90 to 32. Therefore, we performed another TPI and the VAS pain score dropped to 0. We continued SGB and TPI for the next 3 days and the symptoms disappeared. Thus, a combination of TPI and SGB controlled MPS manifested as masseter muscle-mediated nonodontogenic tooth pain.

Effectiveness of ropivacaine trigger points inactivation in the prophylactic management of patients with severe migraine.

OBJECTIVE: Tenderness and referred pain have been described in migraine and involved in its pathogenesis. The present study was performed to evaluate the prophylactic effectiveness of ropivacaine injections during a 12-week period. INTERVENTIONS: A total of 52 patients agreed to participate in the study. Trigger points were explored by manual palpation and injected weekly with 10 mg ropivacaine. The frequencies of migraine attacks were recorded from 4 weeks before the beginning of injections until 4 weeks after the last one, and a Clinical Global Impression improvement scale was completed in the final visit. RESULTS: All of the subjects had one or more trigger points, located in temporal and/or suboccipital areas in most of the cases. In nine (17.3%) patients the frequency of attacks was reduced >or=50%, and in 19 (36.5%) cases the reduction was comprised between 11% and 49%. A total of 31 (59.6%) patients reported to be much or very much improved after finishing the injection period. In 11 cases rescue medication intake was reduced >or=50% in comparison with baseline period, and the attacks of severe intensity decreased significantly. Eight (26.6%) out of 30 patients suffering chronic migraine reverted to episodic migraine. Local pain in injection sites was reported by 14 patients, and 13 subjects (25.5%) experienced postinjection soreness. CONCLUSIONS: Trigger points inactivation can be an effective palliative measure in the prophylactic management of severe refractory migraine.