C57BL/6 substrain differences in formalin-induced pain-like behavioral responses.

Substantial evidence from preclinical models of pain suggests that basal and noxious nociceptive sensitivity, as well as antinociceptive responses to drugs, show significant heritability. Individual differences to these responses have been observed across species from rodents to humans. The use of closely related C57BL/6 inbred mouse substrains can facilitate gene mapping of acute nociceptive behaviors in preclinical pain models. In this study, we investigated behavioral differences between C57BL/6 J (B6 J) and C57BL/6 N (B6 N) substrains in the formalin test, a widely used tonic inflammatory pain model, using a battery of pain-related phenotypes, including reflexive tests, nesting, voluntary wheel running, sucrose preference and anxiety-like behavior in the light/dark test at two different time points (1-h and 24-h). Our results show that these substrains did not differ in reflexive thermal and mechanical responses at the 1-h time point. However, B6 N substrain mice showed increased sensitivity to spontaneous pain-like behaviors. In addition, B6 N substrain continued to show higher levels of mechanical hypersensitivity compared to controls at 24-h. indicating that mechanical hypersensitivity is a more persistent pain-related phenotype induced by formalin. Finally, no sex differences were observed in our outcome measures. Our results provide a comprehensive behavioral testing paradigm in response to an inflammatory agent for future mouse genetic studies in pain.

Transient ischaemic attacks due to a pulsating mass in the neck produced after incision and drainage of parapharyngeal abscess.

Carotid endarterectomy is the most commonly performed vascular surgical procedure. One of the complications of carotid endarterectomy is Pseudoaneurysm of the carotid artery frequently managed by endo-vascular technique. Pseudoaneurysm caused by other aetiological factors is rare entity. Penetrating trauma and neck surgery are known but very rare causes of pseudo aneurysm of the carotid artery. We have successfully managed a case of carotid artery pseudoaneurysm caused by incision and drainage of parapharyngeal abscess. This surgery also leads to the palsy of right vagus nerve causing complete hoarseness of voice. The patient presented with Transit Ischaemic Attacks (TIA) and amurosis fugos. Resection of aneurysm and reconstruction of right carotid artery lead to complete recovery. Vocal cord palsy was managed by Vox implant injection leading to full recovery.