Differential diagnosis of endodontic-related inferior alveolar nerve paraesthesia with cone beam computed tomography: a case report.

AIM: To discuss the use of cone-beam computed tomography (CBCT) in the differential diagnosis of a case of labiomandibular paraesthesia caused by extrusion of endodontic sealer into the mandibular canal. SUMMARY: A 59-year-old woman suffering from a paraesthesia on the left posterior mandible and numbness on the left side of the lower lip was referred to an endodontic specialist 1 month after multiple root canal treatments. A panoramic radiograph revealed the presence of extruded root filling material beyond the apex of the mesial root of the mandibular left second molar and also beyond the apex of the first premolar. A cone beam computed tomography examination was undertaken, which confirmed the presence of radiopaque root canal filling material in the periapical area of the second molar, and revealed that the material was inside the mandibular canal. No extruded filling material was found inside the mental foramen beyond the apex of the first premolar tooth. KEY LEARNING POINTS: Small field of view CBCT (where possible) can be considered an effective radiographic diagnostic device when endodontic-related inferior alveolar nerve or mental foramen paraesthesia are suspected. CBCT is able to provide detailed three-dimensional images of the tooth, the root canal system and the surrounding tissue.

Does computed tomographic assessment of inferior alveolar canal cortical integrity predict nerve exposure during third molar surgery?

PURPOSE: To evaluate the association between computed tomographic (CT) assessment of inferior alveolar nerve (IAN) canal cortical integrity and intraoperative IAN exposure. MATERIALS AND METHODS: This was a retrospective cohort study. The study sample included patients considered at high risk for IAN injury based on panoramic findings. The primary predictor variable was IAN canal integrity (intact or interrupted) assessed on coronal CT images. The secondary predictor variable was length of the cortical defect, in millimeters. The primary outcome variable was intraoperative visualization of the IAN. Other variables were demographic and operative parameters. Bivariate and multiple logistic regression analyses were used to evaluate the unadjusted and adjusted associations between the cortical integrity and IAN exposure. Diagnostic test characteristics were computed for cortical integrity and threshold cortical defect size. A P value < or = 0.05 was statistically significant. RESULTS: The sample consisted of 51 subjects (57% female) with a mean age of 35.2 +/- 12.8 years. Of the 80 third molars available for evaluation, 52 third molars (64.1%) had evidence of loss of cortical integrity. The mean cortical defect length was 2.9 +/- 2.6 mm. Loss of cortical integrity had a high sensitivity (> or = 0.88) but low specificity (< or = 0.49) as a diagnostic test for IAN visualization. A cortical defect size > or = 3 mm was associated with an increased risk for intraoperative IAN visualization with a high sensitivity and specificity (> or = 0.82). CONCLUSION: Cortical defect size on a maxillofacial CT has a high sensitivity and specificity for predicting intraoperative IAN exposure during third molar removal.

Facial palsy after blunt trauma and without facial bone fracture.

A 14-year-old patient had a low-energy facial blunt trauma that evolved to right facial paralysis caused by parotid hematoma with parotid salivary gland lesion. Computed tomography and angiography demonstrated intraparotid collection without pseudoaneurysm and without radiologic signs of fracture in the face. The patient was treated with serial punctures for hematoma deflation, resolving with regression and complete remission of facial paralysis, with no late sequela. The authors discuss the relationship between facial nerve traumatic injuries associated or not with the presence of facial fractures, emphasizing the importance of early recognition and appropriate treatment of such cases.

Removal of a chopstick out of the cavernous sinus, pons, and cerebellar vermis through the superior orbital fissure.

Penetrating non-missile orbito cranial injuries are rare in a civilian pediatric setting. We describe a case of a trans-orbital penetration by a wooden chopstick deep down into the cerebellar vermis detected at neuroradiological examination in a child presenting for head injury. The foreign body was successfully pulled out in one piece surgically.

Evaluation of stress distribution in critical anatomic regions following the Le Fort I osteotomy by three-dimensional finite element analysis.

In this study, we aimed to measure the stresses both on the pterygoid plates and the cranial base during the down-fracture and at the time of pterygomaxillary osteotomy by using the finite element analysis method to have an idea about the possible causes of complications. Three different surgical approaches were applied to the obtained models. In the Model 1, Le Fort I cuts without pterygomaxillary separation was applied. In the Model 2, same standard Le Fort I cuts were applied with pterygomaxillary separation. Then both models were subjected to a force of 150 N over the anterior spina nasalis to simulate down-fracture. In the third model, same standard Le Fort I cuts were applied. Following this procedure, a force of 50 N was applied with a sharp osteotome to the pterygomaxillary junction to simulate osteotomy. According to the results of this experimental study, the cranial base stress values decreased during the down-fracture in the Model 2. Moreover, it was found that the force transmitted to the base of the skull is less when the height of the pterygomaxillary osteotome is limited to 1 cm as we applied in Model 3.

Multiple cranial nerve injuries and neck abscesses caused by a transorally penetrating organic stick.

Foreign bodies cause a remarkable number of otolaryngological emergency visits and occasionally result in life-threatening conditions and later-emerging complications. Patient recovery depends on the detection and proper extraction of all foreign materials. Despite various obtainable diagnostic tools, adequate anamnesis forms the basis of clinical reasoning and should direct later examinations and radiological imaging. This case report describes a challenging patient with a unique trauma mechanism: many pieces of a fragmented organic foreign body emerged within 1 year of the initial injury, leading to repeated operations, a long period in an intensive care unit and a long-term swallowing and speech dysfunction.

A case of traumatic infraorbital neuroma.

A 53-year-old Afghan man presented with a 12-month history of left proptosis, diplopia and facial swelling 20 years after a bomb blast injury. Magnetic resonance and computed tomography imaging revealed a well-circumscribed lesion centred within the left inferior orbit/superior maxillary sinus along with left orbital fracture. Histopathology and immunostaining of the debulked lesion were consistent with traumatic neuroma of the infraorbital nerve. Infraorbital neuromas have developed following orbital decompression surgeries but have not been reported previously following non-surgical trauma.

Inferior alveolar nerve injury related to mandibular third molar surgery: an unusual case presentation.

Perforation of the lower third molar roots by the inferior alveolar nerve is uncommon and can be difficult to determine by conventional radiographic methods. Presented is a case of perforation that was treated by coronectomy, and showed an unusual complication in that the retained root erupted, moving the canal with it. The radiographic assessment of root perforation and the imaging modalities used to assess such cases are discussed.

Imaging of denervation in the head and neck.

Denervation changes maybe the first sign of a cranial nerve injury. Recognition of denervation patterns can be used to determine the site and extent of a lesion and to tailor imaging studies according to the most likely location of an insult along the course of the affected cranial nerve(s). In addition, the extent of denervation can be used to predict functional recovery after treatment. On imaging, signs of denervation can be misleading as they often mimic recurrent neoplasm or inflammatory conditions. Imaging can both depict denervation related changes and establish its cause. This article briefly reviews the anatomy of the extracranial course of motor cranial nerves with particular emphasis on the muscles supplied by each nerve, the imaging features of the various stages of denervation, the different patterns of denervation that maybe helpful in the topographic diagnosis of nerve lesions and the most common causes of cranial nerve injuries leading to denervation.

The prognostic value of panoramic radiography of inferior alveolar nerve damage after mandibular third molar removal: retrospective study of 400 cases.

OBJECTIVE: The aim of the study was to estimate the accuracy of panoramic radiographic signs predicting inferior alveolar nerve (IAN) paresthesia after lower third molar removal. STUDY DESIGN: In a case-control study the sample was composed of 41 cases with postoperative IAN paresthesia and 359 control cases without it. The collected data included "classic" specific signs indicating a close spatial relationship between third molar root and inferior alveolar canal (IAC), root curvatures, and the extent of IAC-root tip overlap. Bivariate and multivariate logistic regression analyses were completed to estimate the association between radiographic findings and IAN paresthesia. RESULTS: The multivariate logistic analysis identified 3 signs significantly associated with IAN paresthesia (P < .001): interruption of the superior cortex of the canal wall, diversion of the canal, and darkening of the root. The sensitivities and specificities ranged from 14.6% to 68.3% and from 85.5% to 96.9%, respectively. The positive predictive values, calculated to factor a 1.1% prevalence of paresthesia, ranged from 3.6% to 10.9%, whereas the negative predictive values >99%. CONCLUSION: Panoramic radiography is an inadequate screening method for predicting IAN paresthesia after mandibular third molar removal.

Cranial nerve injury after minor head trauma.

OBJECT: There are no specific studies about cranial nerve (CN) injury following mild head trauma (Glasgow Coma Scale Score 14-15) in the literature. The aim of this analysis was to document the incidence of CN injury after mild head trauma and to correlate the initial CT findings with the final outcome 1 year after injury. METHODS: The authors studied 49 consecutive patients affected by minor head trauma and CN lesions between January 2000 and January 2006. Detailed clinical and neurological examinations as well as CT studies using brain and bone windows were performed in all patients. Based on the CT findings the authors distinguished 3 types of traumatic injury: no lesion, skull base fracture, and other CT abnormalities. Patients were followed up for 1 year after head injury. The authors distinguished 3 grades of clinical recovery from CN palsy: no recovery, partial recovery, and complete recovery. RESULTS: Posttraumatic single nerve palsy was observed in 38 patients (77.6%), and multiple nerve injuries were observed in 11 (22.4%). Cranial nerves were affected in 62 cases. The most affected CN was the olfactory nerve (CN I), followed by the facial nerve (CN VII) and the oculomotor nerves (CNs III, IV, and VI). When more than 1 CN was involved, the most frequent association was between CNs VII and VIII. One year after head trauma, a CN deficit was present in 26 (81.2%) of the 32 cases with a skull base fracture, 12 (60%) of 20 cases with other CT abnormalities, and 3 (30%) of 10 cases without CT abnormalities. CONCLUSIONS: Trivial head trauma that causes a minor head injury (Glasgow Coma Scale Score 14-15) can result in CN palsies with a similar distribution to moderate or severe head injuries. The CNs associated with the highest incidence of palsy in this study were the olfactory, facial, and oculomotor nerves. The trigeminal and lower CNs were rarely damaged. Oculomotor nerve injury can have a good prognosis, with a greater chance of recovery if no lesion is demonstrated on the initial CT scan.

Position of the impacted third molar in relation to the mandibular canal. Diagnostic accuracy of cone beam computed tomography compared with panoramic radiography.

This study investigated the diagnostic accuracy of cone beam computed tomography (CBCT) compared to panoramic radiography in determining the anatomical position of the impacted third molar in relation with the mandibular canal. The study sample comprised 53 third molars from 40 patients with an increased risk of inferior alveolar nerve (IAN) injury. The panoramic and CBCT features (predictive variables) were correlated with IAN exposure and injury (outcome variables). Sensitivity and specificity of modalities in predicting IAN exposure were compared. The IAN was exposed in 23 cases during third molar removal and injury occurred in 5 patients. No significant difference in sensitivity and specificity was found between both modalities in predicting IAN exposure. To date, lingual position of the mandibular canal was significantly associated with IAN injury. CBCT was not more accurate at predicting IAN exposure during third molar removal, however, did elucidate the 3D relationship of the third molar root to the mandibular canal; the coronal sections allowed a bucco-lingual appreciation of the mandibular canal to identify cases in which a lingually placed IAN is at risk during surgery. This observation dictates the surgical approach how to remove the third molar, so the IAN will not be subjected to pressure.

Inferior alveolar nerve injury related to surgery for an erupted third molar.

Removal of third molars is one of the most common operations performed in oral surgery. A well recognized serious complication of mandibular third molar extraction is injury to the inferior alveolar nerve (IAN). We describe a case of an unusual nerve passage discovered after the extraction of a completely erupted third molar. The likelihood of direct damage to the IAN can be predicted with more specific information obtained by the use of a preoperative computerized tomography scan when conventional radiography does not clearly show the nerve canal.

Panoramic radiographic findings as predictors of inferior alveolar nerve exposure following third molar extraction.

OBJECTIVES: The aim of this study was to estimate the sensitivity and specificity of panoramic radiographic findings in relation to inferior alveolar nerve (IAN) exposure after mandibular third molar (M3) extraction. METHODS: The study used a retrospective cohort model. The primary predictor variable was the presence or absence of > or = 1 panoramic radiographic sign associated with an increased risk for IAN injury. The secondary predictor variable was the surgeons assessment of IAN exposure risk. The outcome variable was IAN exposure, defined as direct visualization of the IAN at the time of M3 extraction. Appropriate univariate and bivariate statistics were computed and the level of statistical significance was set at P < or = .05. RESULTS: The sample was composed of 230 patients having 423 mandibular M3s evaluated and removed. Following M3 extraction, the IAN was visualized in 24 (5.7%) extraction sites. Four of the radiographic signs were statistically associated with IAN exposure ( P < or = .05). The sensitivities and specificities of the 4 radiographic findings ranged from 0.42 to 0.75 and 0.66 to 0.91. The clinicians preoperative estimate of the likelihood of IAN exposure was statistically associated with IAN exposure after M3 extraction ( P < .001; sensitivity = 0.79; specificity = 0.86). CONCLUSION: Four radiographic findings (darkening of the tooth root, narrowing of the tooth root, interruption of the white lines, and diversion of the canal) were statistically associated with IAN exposure following M3 extraction. The surgeons overall estimate of risk based on the panoramic radiograph was also statistically associated with an increased risk of IAN exposure.

Panoramic radiographic risk factors for inferior alveolar nerve injury after third molar extraction.

PURPOSE: The purpose of this study was to estimate the association between specific panoramic radiographic signs and inferior alveolar nerve (IAN) injury during mandibular third molar removal. PATIENTS AND METHODS: A case-control study design was used; the sample consisted of patients who underwent removal of impacted mandibular third molars. Cases were defined as patients with confirmed IAN injury after third molar extraction, whereas controls were defined as patients without nerve injury. Five surgeons, who were blinded to injury status, independently assessed the preoperative panoramic radiographs for the presence of high-risk radiographic signs. Bivariate analyses were completed to assess the relationship between radiographic findings and IAN injury. The sensitivity, specificity, and positive and negative predictive values were computed for each radiographic sign. RESULTS: The sample was composed of 8 cases and 17 controls. Positive radiographic signs were statistically associated with an IAN injury (P <.0001). The presence of radiographic sign(s) had positive predictive values that ranged from 1.4% to 2.7%, representing a 40% or greater increase over the baseline likelihood of injury (1%) for the individual patient. Absence of these radiographic findings had a strong negative (>99%) predictive value. CONCLUSIONS: This study confirms previous analyses showing that panoramic findings of diversion of the inferior alveolar canal, darkening of the third molar root, and interruption of the cortical white line are statistically associated with IAN injury. Based on the estimated predictive values, the absence of positive radiographic findings was associated with a minimal risk of nerve injury, whereas, the presence of one or more of these findings was associated with an increased risk for nerve injury.