Dysesthesia of the inferior alveolar nerve

Abstract

I write in response to a recent article by Nayak et al. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:e48-51) that highlighted a case of dysesthesia resulting from a broken endodontic file. It was indeed a very interesting case report. In it, the authors proposed that the dysesthesia presented in their patient resulted from irritation of the nerve sheath, with a suggestion of Sunderland's first degree of nerve injury. However, it is my belief that the dysesthesia resulted from a higher degree of injury that may have involved some axonal injury, as dysesthesia is not commonly seen in first degree of nerve injury.1Sunderland S. A classification of peripheral nerve injuries producing loss of function.Brain. 1951; 74: 491-516Google Scholar Judging from the vertical position of the broken endodontic file in Fig. 2, it is possible that the file had caused mechanical injury during filing, which breached the epineurium of the inferior alveolar nerve (IAN). This caused some injured axons to continue firing impulses, with the broken file impinging onto them within the narrow mandibular canal (average diameter 3.4 ± 0.5 mm; range 2.0-5.0 mm).2Ikeda K. Ho K.C. Nowicki B.H. Haughton V.M. Multiplanar MR and anatomic study of the mandibular canal.AJNR Am J Neuroradiol. 1996; 17: 579-584Google Scholar, 3Juodzbalys G. Wang H.L. Sabalys G. Anatomy of mandibular vital structures Part I: mandibular canal and inferior alveolar neurovascular bundle in relation with dental implantology.J Oral Maxillofac Res. 2010; 1: e2Google Scholar Of course, the injured epineurium (but not the axons within) may have healed by the time the authors explored the mandibular canal, giving an impression of a lack of physical injury. The long recovery time of 4 months further provides indirect evidence to support the more severe degree of injury, as Sunderland's first degree of nerve injury usually recovers rapidly upon the removal of the source.1Sunderland S. A classification of peripheral nerve injuries producing loss of function.Brain. 1951; 74: 491-516Google Scholar I agree with the authors' explanation for the lack of anesthesia, as Ikeda et al.2Ikeda K. Ho K.C. Nowicki B.H. Haughton V.M. Multiplanar MR and anatomic study of the mandibular canal.AJNR Am J Neuroradiol. 1996; 17: 579-584Google Scholar have shown that there is room between the IAN and the canal, thus minimizing the risk of compression on the nerve (which usually causes typical Sunderland's first degree of injury). In addition, it has to be noted that the IAN within the mandibular canal has been shown to typically have 3 branches.2Ikeda K. Ho K.C. Nowicki B.H. Haughton V.M. Multiplanar MR and anatomic study of the mandibular canal.AJNR Am J Neuroradiol. 1996; 17: 579-584Google Scholar So, injury to one branch, but not the others, will spare the patient from feeling numb but not pain. One last note to share with the authors is to suggest the use of an ultrasound bone surgical device4Bovi M. Mobilization of the inferior alveolar nerve with simultaneous implant insertion: a new technique Case report.Int J Periodontics Restorative Dent. 2005; 25: 375-383Google Scholar to make the required cuts. Such a device has been shown to enable the surgeon to cut hard tissue without injuring the soft tissues, i.e., the IAN. Thank you. Dysesthesia with pain due to a broken endodontic instrument lodged in the mandibular canal—a simple deroofing technique for its retrieval: case reportOral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and EndodonticsVol. 111Issue 2PreviewThis article presents a simple deroofing technique to retrieve a broken endodontic file lodged in the mandibular canal and causing dysesthesia with pain. Many unsuccessful attempts were made to retrieve the broken instrument. The deroofing technique described is simple, requiring local anesthesia and done on an outpatient basis with minimum morbidity. A brief review of the literature on dysesthesia of the inferior alveolar nerve caused by endodontic materials is also presented. Full-Text PDF In replyOral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and EndodonticsVol. 111Issue 6PreviewIn response to the letter to the editor by Dr. Wei Cheong Ngeow about my article titled “Dysesthesia with pain due to a broken endodontic instrument lodged in the mandibular canal—a simple deroofing technique for its retrieval: a case report,” I have the following responses to Dr. Ngeow's comments. Full-Text PDF