A study of cortical and brainstem mechanisms of diffuse noxious inhibitory controls in anaesthetised normal and neuropathic rats

Diffuse noxious inhibitory controls (DNIC) are a mechanism of endogenous descending pain modulation and are deficient in a large proportion of chronic pain patients. However, the pathways involved remain only partially determined with several cortical and brainstem structures implicated. This study examined the role of the dorsal reticular nucleus (DRt) and infralimbic (ILC) region of the medial prefrontal cortex in DNIC. In vivo electrophysiology was performed to record from dorsal horn lamina V/VI wide dynamic range neurones with left hind paw receptive fields in anaesthetised sham‐operated and L5/L6 spinal nerve‐ligated (SNL) rats. Evoked neuronal responses were quantified in the presence and absence of a conditioning stimulus (left ear clamp). In sham rats, DNIC were reproducibly recruited by a heterotopically applied conditioning stimulus, an effect that was absent in neuropathic rats. Intra‐DRt naloxone had no effect on spinal neuronal responses to dynamic brush, punctate mechanical, evaporative cooling and heat stimuli in sham and SNL rats. In addition, intra‐DRt naloxone blocked DNIC in sham rats, but had no effect in SNL rats. Intra‐ILC lidocaine had no effect on spinal neuronal responses to dynamic brush, punctate mechanical, evaporative cooling and heat stimuli in sham and SNL rats. However, differential effects were observed in relation to the expression of DNIC; intra‐ILC lidocaine blocked activation of DNIC in sham rats but restored DNIC in SNL rats. These data suggest that the ILC is not directly involved in mediating DNIC but can modulate its activation and that DRt involvement in DNIC requires opioidergic signalling.     

腮腺良性肿瘤切除术中腮腺导管和面神经颊支解剖关系的观察

目的观察研究腮腺导管与面神经颊支的解剖关系，为术中用腮腺导管作为面神经探查标记物提供解剖依据。方法在腮腺良性肿瘤切除术中观察和测量42例患者的腮腺导管和面神经颊支的解剖关系，包括深浅、成角和距离关系。结果在深浅关系上，颊支位于腮腺导管浅面占69.05%（29/42），同层面占14.29%（6/42），深面占16.67%（7/42）。从二者走形角度上，基本平行占76.19%（32/42），明显成角的占23.81%（10/42）。以出腮腺处测量距离来看，上颊支位于腮腺导管上0.2~1.0 cm，平均（0.61±0.13）cm；下颊支位于导管下0.2~1.5 cm，平均（0.77±0.27）cm。结论腮腺导管与面神经上下颊支解剖关系相对恒定，可以用于腮腺肿瘤术中寻找解剖面神经的标志物。     

Do positional changes of the inferior alveolar canal after sagittal split mandibular osteotomy affect neurosensory recovery?

The purpose of this study was to assess the pre- and postoperative position and dimensions of the inferior alveolar canal (IAC) following sagittal split osteotomy (SSO) and identify any association with postoperative neurosensory deficit (NSD) at 1 year. This retrospective cohort study enrolled consecutive patients who had SSO performed to correct skeletal malocclusion. The pre- and postoperative cone beam computed tomography data were superimposed to visualize differences in IAC position and dimensions. Subjective and objective neurosensory tests were used to determine NSD in the inferior alveolar nerve distribution. A total of 20 subjects were included. The preoperative distance from the lateral cortex of the IAC to the inner aspect of the lateral cortex of the mandible was significantly greater in sides with NSD when compared to sides without NSD (P = 0.01). A significantly greater reduction in the postoperative distance measurement was seen in sides with NSD when compared to sides without NSD (P = 0.01). The magnitude of mandibular movement was significantly increased in sides with NSD (P = 0.02). The preoperative location of the IAC, as well as certain changes in the mediolateral and vertical positions as a result of SSO, are risk factors for postoperative NSD.     

Trigeminal trophic syndrome: An unusual nasal ulceration. A case report and review of the literature

Trigeminal trophic syndrome is a rare condition characterized by self-inflicted persistent facial ulceration. It is believed to be consequent to central or peripheral insult to trigeminal nerve, which may have taken place even years before the ulcer development. The aggression to the nerve pathway causes dysesthesias in the trigeminal dermatomes that induce a self-mutilating behavior, with repetitive pinching or scratching in order to mitigate the altered sensation. Due to associated skin anesthesia, the patient does not interrupt manipulation of the affected area despite severe skin necrosis. Ulceration typically occurs in the ala nasi and may resemble other more common cutaneous diseases, such as tumors or infections. Given that this condition is not included in our daily clinical practice, the risk is that of a diagnostic delay with devastating functional and esthetic facial consequences. We present the case of a patient with a history of meningioma resection who developed this syndrome and we have reviewed the published literature to provide an update on the etiopathogenesis, diagnosis and treatment of this rare condition.