Trigeminal Nerve Injuries

Assessment and Correlation of Variation in Lingual Cortical Plate Thickness with Different Angulations of Impacted Mandibular Third Molar Using Cone Beam Computed Tomography in North Indian Population

Purpose

The extraction of impacted mandibular third molar is associated with various types of intraoperative and postoperative complications, one of them is injury to lingual nerve. The present study aims to assess and correlate the variation in lingual cortical plate thickness with different angulations and determine the topographic relationship between the root apex of impacted mandibular third molar and lingual cortical plate using Cone Beam Computed Tomography (CBCT).

Methods

This prospective cohort study enrolled 140 patients with impacted mandibular third molars who underwent preoperative CBCT imaging. The CBCT images were used to evaluate the outcome variables such as lingual cortical plate thickness and topographical relationship between root apex of impacted mandibular third molar and lingual cortical plate. The predictor variables included age, gender, inclination of third molar, mesiodistal angle, buccolingual angle and lingual plate morphology.

Results

The temporary lingual nerve paresthesia was reported by 1 patient (0.71%) out of 140 patients. The lingual bone in distoangular and vertical impacted third molar was found to be 1.20 times thicker than mesioangular and horizontal teeth. Lingual bone thinning at mid-root level was observed in maximum number of cases with mesioangular teeth (68.5%), whereas horizontal impacted teeth showed lingual bone thinning (90.9%) at root apex level. The mean buccolingual angle of impacted mandibular third molar was found to be significantly associated with lingual bone perforation (p value = 0.0258). The morphology of lingual plate was observed as undercut type (37.14%) followed by slanted (36.43%), parallel (19.29%) and round type (7.14%).

Conclusion

Increase in buccolingual angle of impacted mandibular third molar decreases lingual bone thickness which is the natural barrier for protecting injury to lingual nerve. Also undercut and slanted lingual plate shapes were recognised as risk factors for contact/perforation between root apex and lingual plate. Therefore, proper screening and planning of high risk patients before third molar extraction is crucial.

Injuries of the Peripheral Mandibular Nerve, Evaluation of Interventions and Outcomes: A Systematic Review

Trigeminal nerve injuries are common and there is currently no consensus on both timing and type of intervention to achieve the best outcomes. A systematic review was performed to compare the outcomes of the many different types of therapeutic interventions for nerve injury. PubMed, EBSCO, and Cochrane Review databases were used to search for studies published from January 1, 2000 to December 31, 2019. Included studies detailed treatment of an injury to peripheral branches of the trigeminal nerve, either known transection or injury causing persistent alteration in sensation. The primary outcome was functional sensory recovery via the Medical Research Council scale. Twenty studies were included, detailing outcomes of 608 subjects undergoing intervention for 622 nerve injuries. Surgical interventions were able to achieve functional sensory recovery in approximately >80% or more of the subjects. There was heterogeneity among how procedures were performed, timing to intervention, and methods of measuring recovery. The data of this study supports the ability of surgical intervention to achieve functional sensory recovery in a significant number of subjects, and found evidence for better outcomes with intervention closer to the time of injury.

Profiling thermal pain using quantitative sensory testing in patients with trigeminal nerve injury

OBJECTIVES

To investigate the thermal pain phenotypes using QST in patients with unilateral trigeminal nerve injury and to explore whether these different thermal pain phenotypes are associated with clinical and psychophysical characteristics.

METHODS

This retrospective study included 84 patients diagnosed with posttraumatic trigeminal neuropathy involving inferior alveolar nerve (IAN) and lingual nerve (LN). Data on clinical characteristics, subjective symptoms including hypoesthesia, dysesthesia, and allodynia, and objective signs using thermal QST were collected and explored.

RESULTS

Three heat (heat hypoalgesia, heat hyperalgesia, and within normal range) and cold pain phenotypes (cold hypoalgesia, cold hyperalgesia, and within normal ranges) were identified, respectively. Thermal hypoalgesia was more frequently observed than thermal hyperalgesia. Heat hypoalgesia regardless of cold pain abnormalities appears to be associated with subjective negative symptoms, while thermal hyperalgesia seems to have little relationship with negative and positive symptoms. Thermal pain phenotypes were associated with loss of innocuous thermal sensation. Unlike heat pain phenotypes, cold pain phenotypes differed between IAN injury and LN injury.

CONCLUSION

The thermal pain phenotypes identified in this study seem to be related to clinical and psychophysical findings differently. These results would be a good starting point for assessing posttraumatic trigeminal neuropathy and interpreting the thermal QST results.

Numb Chin Syndrome as the Initial Manifestation of Breast Carcinoma

Numb chin syndrome may be the manifestation of a local dental pathology or secondary to a systemic disease. A systematic physical examination with diagnostic workup is of utmost importance in patients presenting with numb chin syndrome. We report the case of a 58-year-old woman who presented with numb chin syndrome. An orthopantogram and computed tomography of the head revealed osteolytic lesion in the left molar region. Histopathological and immunohistochemical examination confirmed the lesion to be metastatic breast carcinoma. Breast ultrasound scan demonstrated a 1.5 × 1.5-cm lesion in the left breast and fine needle aspiration cytology from the lesion confirmed the diagnosis of breast carcinoma. Bone scan showed multiple bone metastases. She was diagnosed to have numb chin syndrome secondary to bone metastases from breast carcinoma. In view of her disseminated disease status, she was started on palliative hormone therapy (Letrozole) with zoledronic acid. We present this case to highlight the importance of careful evaluation of patients presenting with numb chin syndrome because this may be the only manifestation of a systemic malignancy.

Surgical treatment of painful inferior alveolar nerve injuries following endodontic treatment: a consecutive case series of seven patients

PURPOSE

Injuries of the inferior alveolar nerve (IAN) related to endodontic treatment are being increasingly reported. However, consensus on the preferred intervention and the timing of and indications for surgical treatment is lacking. Here, we describe our experience with painful IAN injuries arising from endodontic treatment and requiring prompt microsurgical treatment.

METHODS

Seven consecutive patients with painful IAN injuries were referred to the Maxillofacial Surgery Unit of San Paolo Hospital in Milan. All patients had undergone root canals endodontic treatment in the mandibular molar or premolar between 2007 and 2014. The time elapsed between injury and referral for surgical treatment ranged from 10 days to 20 months. Each patient was treated by one of several different microsurgical procedures, described herein.

RESULTS

Overall, neurosensory status and IAN-related pain improved in all seven patients. The best results were obtained by IAN replacement with a sural nerve graft. However, complete sensory recovery was not achieved in any of the patients.

CONCLUSIONS

Although our sample includes only seven patients, early surgical treatment with an interpositional sural nerve graft seems to allow neurosensory recovery. Less satisfactory results are achieved in patients with IAN injuries of > 12 months duration.