Imaging of Trigeminal Neuralgia and Other Facial Pain.

We review and illustrate the radiology of facial pain, emphasizing trigeminal neuralgia, relevant anatomy, current classification, concepts about etiology, and the role of imaging and its influence on the choice of treatment. We discuss glossopharyngeal neuralgia, other neuropathic causes of facial pain, postinflammatory and neoplastic causes, and nociceptive (end-organ) causes of facial pain, as well as referred otalgia. Other conditions that may present with facial pain, including trigeminal autonomic cephalgias and giant cell arteritis, are reviewed briefly. We discuss the elements of a comprehensive MR imaging protocol to enable detection of these diverse causes of facial pain.

Three-phase four-dimensional computed tomography as a first-line investigation in primary hyperparathyroidism.

INTRODUCTION: Parathyroid computed tomography using multiple phases (four-dimensional computed tomography (4DCT) for parathyroid localization was first described in 2006. Since its inception, there has been variable uptake of this technique due to inconsistency of results between institutions and perceived higher radiation dose than technetium-99 sestamibi scans (MIBI). 4DCT has been the primary imaging modality for parathyroid localization at our institution since 2013. METHODS: A retrospective study of surgically managed patients with primary hyperparathyroidism who had preoperative localization with 4DCT from 2013-2018 was performed. RESULTS: A total of 353 patients were included for analysis. The positive predictive value (PPV) of our three-phase 4DCT protocol was 93.3%, sensitivity (localized) 85.2% with a 5.8% false-positive rate and 13.9% false-negative (non-localizing) rate when reported by a head and neck radiologist (HNR). Calculated effective dose varied from 4.5 to 8.9mSV. On multivariable logistic regression, reporting by an experienced HNR (P < 0.001) and gland weight > 200 mg (P = 0.002) were significant for higher accuracy, lower false positives and false negatives. CONCLUSION: A first-line three-phase 4DCT protocol for primary hyperparathyroidism is an accurate technique providing precise anatomical localization of abnormal parathyroid glands, particularly when performed by a specialist HNR. In our practise, it provides the best rate of detection and superior anatomical localization needed for minimally invasive parathyroid surgery, compared to other commonly used localization techniques. It also avoids the need for four gland exploration in the majority of patients with primary hyperparathyroidism.

Imaging of temporomandibular disorder and its mimics.

Temporomandibular disorders are common, especially in young to middle-aged women, and most settle with supportive treatment. MRI is the accepted reference standard for the evaluation of the temporomandibular joint and is indicated when significant internal derangement is suspected, in those who do not respond to conservative management and when the diagnosis is no doubt. Multiple pathological processes involving the temporal bone, upper pharynx and neck can mimic temporomandibular disorder secondary to anatomical proximity and referred pain related to shared sensory innervation.

The maxillary sinus: physiology, development and imaging anatomy.

OBJECTIVES: The maxillary sinus is of paramount importance for otolaryngologists, rhinologists, oral and maxillofacial surgeons, head and neck and dental and maxillofacial radiologists. A comprehensive review article concerning the physiology, development and imaging anatomy was undertaken. METHODS: Relevant literature pertaining to the physiology of the sinonasal cavity, development of the paranasal sinuses and imaging anatomy of the maxilla and maxillary sinus from 2000 to 2019 was reviewed. Emphasis was placed on literature from the last 5 years. RESULTS: Extensive recent research using imaging has provided new insights into the development of the maxillary sinus, the other paranasal sinuses and the midface. The fundamental physiological concept of mucociliary clearance and its role in sinus health is emphasized. The paranasal sinuses are an integral part of a common mucosal organ formed by the upper and lower airway.An in-depth understanding of the soft-tissue and neurovascular relationships of the maxillary sinus to the deep fascial spaces and branches of the trigeminal nerve and external carotid artery respectively is required to evaluate and report imaging involving the maxillary sinus.Sinusitis of rhinogenic, rather than odontogenic origin, originates from nasal inflammation followed by anterior ethmoid disease and secondary obstruction of the ostiomeatal unit. The role of anatomical variants that predispose to this pattern of disease is discussed in detail with illustrative examples.The maxillary sinus is intimately related to the roots of the posterior maxillary teeth; the high frequency of mucosal disease and sinusitis of odontogenic aetiology is now well recognized. In addition, an understanding of the anatomy of the alveolar process, morphology of the alveolar recess of the maxillary sinus and neurovascular supply are essential both for deliberate surgical intervention of the sinus and complications related to oral surgical procedures. CONCLUSIONS: An understanding of the fundamental principles of the development, physiology, anatomy and relationships of the maxillary sinus as depicted by multi-modality imaging is essential for radiologists reporting imaging involving the paranasal sinuses and midface.

Condylar position assessed by magnetic resonance imaging after various bite position registrations.

INTRODUCTION: In this study, we evaluated the reliability and validity of 3 bite registrations in relation to condylar position in the glenoid fossae using magnetic resonance imaging in a symptom-free population. METHODS: Nineteen subjects, 14 men and 5 women (ages, 20-39 years) without temporomandibular disorders were examined. Three bite registrations were taken and evaluated on each subject: centric occlusion, centric relation, and Roth power centric relation. The differences in condyle position among the 3 bite registrations were determined for the left and right condyles: centric occlusion-centric relation, centric occlusion-Roth power centric relation, and centric relation-Roth power centric relation for each plane of space. RESULTS: The results indicated that (1) all measurements collected had large standard deviations and ranges with no statistical significance, and (2) of the 19 subjects and 38 condyles assessed, 33 condyles (87%) were concentric in an anteroposterior plane. In the transverse anatomic plane, all condyles were concentric. CONCLUSIONS: The clinical concept of positioning the condyles in specific positions in the fossae with various bite registrations as a preventive measure for temporomandibular disorders and as a diagnosis and treatment planning tool is not supported by this study.

Computed tomography of the temporomandibular joint.

We present a pictorial review of the spectrum of temporomandibular joint (TMJ) pathology diagnosed with CT. Although MRI is the modality of choice for most TMJ pathology, CT is useful when MRI is contraindicated or not accessible. With attention to technique and viewing conditions, CT is capable of showing internal disc derangement, arthritis, neoplasms and non-TMJ regional pathology at a relatively low radiation dose.

Leprosy presenting as orofacial pain: case report.

This article reports an unusual case of neuropathic orofacial pain secondary to leprosy. To the authors' knowledge, it is the first case of leprosy reported in the Western literature that was initially thought to be dental pain, then mistaken as a temporomandibular disorder before the correct diagnosis was made. The patient had migrated to Australia from India 24 years previously and was otherwise healthy without any overt features suggestive of infection. A review of the literature revealed that the trigeminal nerve is frequently involved in leprosy, usually associated with sensory loss rather than neuropathic pain. Even in Western countries, patients originally from countries where leprosy is endemic may develop symptoms of the disease many years later. The possibility of leprosy should be considered in the diagnosis of neuropathic orofacial pain in such patients.

Otitic meningitis, superior semicircular canal dehiscence, and encephalocele: a case series.

BACKGROUND: Otitic meningitis in the postantibiotic era is still a serious condition, requiring intensive treatment and prolonged rehabilitation. In view of the significant morbidity and mortality rate, conditions that may increase the likelihood of otitic meningitis developing should be treated promptly. The incidence of meningitis after asymptomatic encephaloceles of the middle cranial fossa varies greatly, and the management differs between elective surgical repair and expectant careful observation. Superior semicircular canal dehiscences (SSCDs) are postulated to have a congenital origin and are associated with a thin or dehiscent tegmen. Several cases of simultaneous SCCD and tegmen defects have been reported, but the findings of otitic meningitis, SCCD, and encephaloceles has, to the best of our knowledge, not been previously explored in the literature. METHODS: We reviewed a series of 4 patients who all presented with a combination of otitic meningitis, encephaloceles, and SSCD. RESULTS: All the 4 patients we reviewed had meningitis secondary to otitis media with computed tomographic scans confirming the presence of SCCD with ipsilateral tegmen tympani defects and associated cephaloceles. All patients were treated with intravenous antibiotics and underwent surgery that ranged from myringotomy and ventilation tube insertions, mastoidectomy, and burr hole drainage for temporal lobe abscess. They were all associated with intensive care unit admission, significant morbidity, and prolonged hospital stays. There were no mortalities. CONCLUSION: We propose that in all SSCD patients, a careful computed tomographic examination of the cranial base should be undertaken to exclude other associated tegmen tympani defects. In cases of SSCD requiring surgery, we support the view that elective surgical repair be recommended where asymptomatic ipsilateral encephaloceles are found, to reduce the risk of otitic meningitis.

15th Yahya Cohen Memorial Lecture - the relationship between the air-bone gap and the size of superior semicircular canal dehiscence.

INTRODUCTION: This study aimed to examine the relationship between the air-bone gap (ABG) and the size of the superior semicircular canal dehiscence (SSCD) as measured on a computed tomography (CT) scan. MATERIALS AND METHODS: The study design was a case series with chart review. Twenty-three patients (28 ears) from a tertiary referral centre were diagnosed with SSCD. The size of the dehiscence on CT scans and the ABG on pure-tone audiometry were recorded. RESULTS: The size of the dehiscence ranged from 1.0 to 6.0 mm (mean, 3.5 ± 1.6 mm). Six ears with a dehiscence measuring less than 3.0 mm did not have an ABG (0 dB). The remaining 18 ears showed an average ABG at 500, 1000, and 2000 Hz (AvABG(500-2000)) ranging from 3.3 to 27.0 dB (mean, 11.6 ± 5.7 dB). The analysis of the relationship between the dehiscence size and AvABG(500-2000) revealed a correlation of R(2) = 0.828 (P <0.001, quadratic fit) and R(2) = 0.780 (P <0.001, linear fi t). Therefore, the larger the dehiscence, the larger the ABG at lower frequencies on pure-tone audiometry. CONCLUSION: In SSCD patients, an ABG is consistently shown at the low frequency when the dehiscence is larger than 3 mm. The size of the average ABG correlates with the size of the dehiscence. These findings highlight the effect of the dehiscence size on conductive hearing loss in SSCD and contribute to a better understanding of the symptomatology of patients with SSCD.

The relationship between the air-bone gap and the size of superior semicircular canal dehiscence.

OBJECTIVE: To examine the relationship between the air-bone gap (ABG) and the size of the superior semicircular canal dehiscence (SSCD) as measured on a computed tomography (CT) scan. STUDY DESIGN: Case series with chart review. SETTING: Tertiary referral center. PATIENTS: Twenty-three patients (28 ears) diagnosed with SSCD. MAIN OUTCOME MEASURES: The size of the dehiscence on CT scans and the ABG on pure-tone audiometry were recorded. RESULTS: The size of the dehiscence ranged from 1.0 to 6.0 mm (mean, 3.5 +/- 1.6 mm). Six ears with a dehiscence measuring less than 3.0 mm did not have an ABG (0 dB). The remaining 18 ears showed an average ABG at 500, 1000, and 2000 Hz (AvABG(500-2000)) ranging from 3.3 to 27.0 dB (mean, 11.6 +/- 5.7 dB). The analysis of the relationship between the dehiscence size and AvABG(500-2000) revealed a correlation of R(2) = 0.828 (P < 0.001, quadratic fit) and R(2) = 0.780 (P < 0.001, linear fit). Therefore, the larger the dehiscence, the larger the ABG at lower frequencies on pure-tone audiometry. CONCLUSIONS: In SSCD patients, an ABG is consistently shown at the low frequency when the dehiscence is larger than 3 mm. The size of the average ABG correlates with the size of the dehiscence. These findings highlight the effect of the dehiscence size on conductive hearing loss in SSCD and contribute to a better understanding of the symptomatology of patients with SSCD.

The effects of superior semicircular canal dehiscence on the labyrinth: does size matter?

BACKGROUND: Superior semicircular canal dehiscence (SSCD) is characterized by lack of bony covering of the superior semicircular canal in the inner ear, resulting in a third mobile window with altered functioning of the superior semicircular canal. Vertigo in association with sound and pressure changes often occurs. This study examines the relationship between dehiscence size and frequency of sound-induced vertigo. METHOD: Retrospective review of 22 patients with SSCD, noting the auditory frequency producing the maximal electronystagmographic response. RESULTS: The study found a correlation between dehiscence size and stimulator frequency of r = 0.856, p < 0.001. The larger the dehiscence, the lower the frequency of stimuli required to provoke a vestibular response. CONCLUSION: The relationship found between the superior canal dehiscence size and the stimulator frequency has clinical implications in the diagnosis and management of patients with SSCD.

Current concepts in maxillofacial imaging.

A review of state-of-the-art maxillofacial imaging is presented. Current imaging techniques include intra-oral radiographs, dental panoramic tomography, multidetector helical computed tomography, cone-beam computed tomography (CBCT) and magnetic resonance imaging (MRI). The commonest conditions encountered in clinical radiological practice are reviewed, including maxillofacial deformities, complicated dental impactions, maxillofacial trauma, jaw lesions (cysts, neoplasms, fibro-osseous lesions (FOLs) and infections), and temporomandibular joint pathology. Pre-operative assessment for dental implant placement is also briefly reviewed.