• Claire R Morgan, Emma V Bird, Peter P Robinson, and Fiona M Boissonade.
• Department of Oral and Maxillofacial Medicine and Surgery, School of Clinical Dentistry, University of Sheffield, Sheffield, UK. c.morgan@shef.ac.uk
• J Orofac Pain. 2009 Jan 1; 23 (1): 65-72.

AimsRecent evidence suggests that the purinoceptor P2X7 may be involved in the development of dysesthesia following nerve injury, therefore, the aim of the present study was to investigate whether a correlation exists between the level of P2X7 receptor expression in damaged human lingual nerves and the severity of the patients' symptoms.MethodsNeuroma-in-continuity specimens were obtained from patients undergoing surgical repair of the damaged lingual nerve. Specimens were categorized preoperatively according to the presence or absence of dysesthesia, and visual analog scales scores were used to record the degree of pain, tingling, and discomfort. Indirect immunofluorescence using antibodies raised against S-100 (a Schwann cell marker) and P2X7 was employed to quantify the percentage area of S-100 positive cells that also expressed P2X7.ResultsP2X7 was found to be expressed in Schwann cells of lingual nerve neuromas. No significant difference was found between the level of P2X7 expression in patients with or without symptoms of dysesthesia, and no relationship was observed between P2X7 expression and VAS scores for pain, tingling, or discomfort. No correlation was found between P2X7 expression and the time between initial injury and nerve repair.ConclusionThese data show that P2X7 is expressed in human lingual nerve neuromas from patients with and without dysesthesia. It therefore appears that the level of P2X7 expression at the injury site may not be linked to the maintenance of neuropathic pain after lingual nerve injury.

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