Neurosensory changes in the infraorbital nerve following zygomatic fractures

Guidelines and recommendations for assessment of somatosensory function in oro-facial pain conditions--a taskforce report

The goals of an international taskforce on somatosensory testing established by the Special Interest Group of Oro-facial Pain (SIG-OFP) under the International Association for the Study of Pain (IASP) were to (i) review the literature concerning assessment of somatosensory function in the oro-facial region in terms of techniques and test performance, (ii) provide guidelines for comprehensive and screening examination procedures, and (iii) give recommendations for future development of somatosensory testing specifically in the oro-facial region. Numerous qualitative and quantitative psychophysical techniques have been proposed and used in the description of oro-facial somatosensory function. The selection of technique includes time considerations because the most reliable and accurate methods require multiple repetitions of stimuli. Multiple-stimulus modalities (mechanical, thermal, electrical, chemical) have been applied to study oro-facial somatosensory function. A battery of different test stimuli is needed to obtain comprehensive information about the functional integrity of the various types of afferent nerve fibres. Based on the available literature, the German Neuropathic Pain Network test battery appears suitable for the study of somatosensory function within the oro-facial area as it is based on a wide variety of both qualitative and quantitative assessments of all cutaneous somatosensory modalities. Furthermore, these protocols have been thoroughly described and tested on multiple sites including the facial skin and intra-oral mucosa. Standardisation of both comprehensive and screening examination techniques is likely to improve the diagnostic accuracy and facilitate the understanding of neural mechanisms and somatosensory changes in different oro-facial pain conditions and may help to guide management.

Sensory action potentials of the maxillary nerve: a methodologic study with clinical implications

PURPOSE

Recently, recording of sensory nerve action potentials (SNAPs) of the inferior alveolar nerve (IAN) was described and is used as a diagnostic test of traumatic neuropathic trigeminal disorders. The technique is limited to IAN damage; therefore, we adapted the technique to the maxillary nerve, which is also frequently injured by either trauma or orthognathic surgery.

PATIENTS AND METHODS

Fourteen healthy volunteers participated in this methodologic study in which the infraorbital nerve (ION) was stimulated with 2 needle electrodes. The SNAPs were recorded from the maxillary nerve with a unipolar needle electrode close to the foramen rotundum.

RESULTS

The mean latency of the SNAPs was 0.73 ms (95% CI, 0.55 to 0.85 ms) with a 0.08+/-0.09 ms interside difference. The mean baseline to peak amplitude was 31.3+/-7.0 microV (95% CI, 24.2 to 38.3 microV) with a 6.5+/-32.4 microV interside difference. Repeated tests within a session test demonstrated no significant differences in the latency data (ANOVA: P= .225) or amplitude data (ANOVA: P= .44). Stimulus-response curves indicated that the SNAPs saturated at 5.1+/-4.4 mA stimulus intensity. In 1 subject, stimulation of the mental nerve elicited SNAPs (latency: 1.6 ms; amplitude 38 microV) in accordance with published values. A local anesthetic block of the ION was associated with a distinct decay of the SNAP in 1 subject.

CONCLUSION

We suggest that SNAPs of the maxillary nerve can be a valuable technique for a comprehensive examination of the trigeminal system.

MOC-PSSM CME article: Zygomatic fractures

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand the common signs, symptoms, and treatment options for zygomatic fractures. 2. Answer basic questions on therapy for zygomatic fractures.

SUMMARY

This maintenance of certification article on zygomatic fractures attempts to review the current approaches to the treatment of these fractures. Although the article does not deal with extended approaches to treatment, it does in a general sense present the preoperative, intraoperative, and postoperative thinking for the plastic surgeon approaching these patients in general practice. A further in-depth review can be obtained through the references at the end of the article.

Evidence of chorda tympani dysfunction in patients with burning mouth syndrome

BACKGROUND

More than two-thirds of patients with burning mouth syndrome (BMS) have altered taste sensation. The authors conducted a study to assess chorda tympani and trigeminal nerve function in these patients.

METHODS

The study was composed of 48 patients; 22 were diagnosed as having BMS, 14 had burning symptoms related to other diseases and were diagnosed as having secondary burning mouth syndrome (SBMS), and 12 were healthy volunteers. The authors evaluated the electrical detection thresholds of the infraorbital and mental nerves and the electrical taste and electrical detection/tingling thresholds in the anterior two-thirds of the tongue for all patients. Electrical taste threshold is thought to be dictated by chorda tympani nerve function while electrical detection/tingling thresholds are regulated by trigeminal nerve function.

RESULTS

The mean electrical taste/tingling detection thresholds ratio and the taste detection thresholds were significantly higher in patients with BMS than in patients with SBMS and in control subjects, indicating chorda tympani nerve dysfunction. Eighteen (82 percent) of the 22 patients with BMS demonstrated chorda tympani dysfunction (13 unilateral and five bilateral).

CONCLUSIONS

Chorda tympani hypofunction may play an important role in BMS pathology. Unilateral hypofunction may be sufficient to produce generalized burning sensation exceeding the affected nerve area.

CLINICAL IMPLICATIONS

Elevated taste detection threshold levels determined via electrogustatory testing and an elevated taste/tingling detection thresholds ratio may assist clinicians in the diagnosis of BMS. More studies are needed to validate these findings.

Management of neuropathic orofacial pain

Current management of painful trigeminal neuropathies relies on pharmacological (topical and systemic), surgical, and complementary modalities. There is, however, a lack of quality research relating to the effectiveness of these modalities. In this review we analyze the available data that relates to the therapy of trigeminal neuralgia, postherpetic neuralgia, and posttraumatic neuropathies and provide clinical guidelines. The review focuses on medical management, as well as surgical and other interventions for painful neuropathies.

Painful posttraumatic trigeminal neuropathy: a case report of relief with topiramate

A case of chronic neuropathic pain in the infraorbital region following an untreated displaced zygomatic fracture is presented. The case responded favorably to topiramate and sensory testing revealed signs of nerve damage that remained unchanged over the follow-up period (six months) parallel to an analgesic effect. The clinical pharmacology of topiramate, which is reviewed, includes enhanced neuronal stability and neuroprotection, making it a possible candidate in the treatment of painful orofacial neuropathies.