Imaging of Temporal Bone Trauma

Vascular injury arising from lateral skull base fractures

PURPOSE

Although uncommon, vascular injury can be seen in patients with lateral skull base fractures (LSBF). However, little is known about this potentially life-threatening comorbidity. The objective of this study is to better characterize the vascular injuries associated with temporal and lateral sphenoid bone fractures.

BASIC PROCEDURES

Retrospective review of all patients with computed tomography angiography (CTA) performed specifically to evaluate for vascular injury following LSBF. In addition to patient demographics (age, gender, race), the mechanism of injury, the location of fracture(s), and the nature of vascular injury diagnosed by CTA was recorded. Two-way ANOVA was performed to determine if any variables were predictive of vascular injury.

MAIN FINDINGS

From 2011 to 2021, 143 patients with 333 subsite fractures met inclusion criteria. Of all patients, 46 (32.2 %) had CTA evidence of at least one vascular injury, the most common type being venous thrombosis/filling defect (41.7 %). Evidence of vascular injury was unclear in 14 patients (9.8 %). Fractures most associated with vascular injury ranged from 0.7 % (otic capsule fractures) to 26.7 % (mastoid, lateral sphenoid fractures). Risk of vascular injury was no different between patients with single vs multiple fractures. There were no fracture locations that could reliably predict specific vascular injury.

CONCLUSIONS

Over 40 % of all CTAs ordered following LSBF identified were suspicious for associated vascular injury. Yet fracture location and number cannot reliably predict vascular injury. Until such determinants can be better identified, clinicians should have a low threshold to obtain CTA to rule out associated vascular injury.

Improved Prediction of Hearing Loss after Temporal Bone Fracture by Applying a Detailed Classification for Otic Capsule-Violating Fracture: A Wide Scope Analysis with Large Case Series

INTRODUCTION

This study aimed to analyze the predictability of temporal bone (TB) fracture-associated hearing loss by applying a detailed classification separating individual injury of the cochlea, vestibule, and semicircular canals (SCC).

METHODS

In this retrospective study, patients with otic capsule-violating (OCV) fractures were further classified as OCV-C(VS) when the cochlea was involved regardless of vestibule or SCC involvement, OCV-V(S) when the vestibule was involved regardless of SCC involvement, and OCV-S when the fracture only involved SCC. Hearing changes were compared by applying the above-mentioned classification, and TB fracture-induced facial palsy was also analyzed.

RESULTS

A total of 119 patients were included. Patients with OCV fractures had significantly worse bone conduction (BC) and air conduction (AC) thresholds (59.1 ± 25.3 and 87.0 ± 29.5 dB) than those with otic capsule-sparing (OCS) fractures (20.1 ± 17.9 and 36.5 ± 21.9 dB; p < 0.001 for each comparison). The BC and the AC thresholds of OCV-C(VS) (77.5 ± 11.0 and 114.2 ± 14.3 dB) and OCV-V(S) (69.3 ± 27.7 and 98.0 ± 22.2 dB) were significantly higher than OCV-S (40.1 ± 22.9 and 62.1 ± 25.6 dB; p < 0.001 for each comparison). The BC hearing thresholds were not significantly improved in the last pure tone audiometry when compared for total, OCV, or OCS cases. The AC threshold significantly improved in OCS cases. In a considerable number of cases with facial palsy, causative fracture lines involved the geniculate ganglion or tympanic segment without the involvement of the otic capsule. Most cases showed significant improvement; however, recovery was limited in cases with obvious fallopian canal disruption.

CONCLUSIONS

The cases with sole involvement of SCC had significantly better hearing thresholds than those with cochlear or vestibule involvement, even in OCV fracture cases.

[Traumatology of the lateral skull base]

The most common cause of lateral skull base fractures are still road traffic accidents, followed by falls. The radiologic classification into otic capsule-sparing or otic capsule-violating fractures correlates well with an increased risk of injury to the sensitive structures of the middle ear with otic capsule-violating fractures. In case of immediate onset complete facial nerve paralysis, decompression surgery is generally recommended if bony impingement can be demonstrated on high-resolution CT of the temporal bone. For many other facials nerve complications, recent publications have achieved good to excellent facial nerve recovery rates with watchful waiting under conservative treatment with prednisolone administration.

Emergency radiologic approach to mastoid air cell fluid

Mastoid air cell fluid is a commonly seen, but often dismissed finding. Given the location of the mastoid portion of the temporal bone and its location adjacent to vital structures, a careful evaluation is important for the emergency radiologist. While occasionally benign, fluid within the mastoid air cells can be an early sign of more severe pathology, and familiarity of regional anatomy allows for early identification of disease spread. This article describes the important anatomy, the common pathologies, and a radiologic approach to assessing the mastoid air cells in order to guide referring clinicians.

Traumatic Tympanic Bulla Fracture in a Cat With Severe Head Trauma

A nine-year-old male European shorthair cat was referred to our practice with severe head trauma after suffering a road traffic accident (RTA). The patient presented marked facial swelling and multiple skin wounds and bruising, inspiratory dyspnea, palpable mandibular and maxillary fractures, serosanguinolent oronasal discharge and right eye exophthalmos and buphthalmos with loss of menace and pupillary reflex. After stabilizing the patient, a CT scan was performed under general anesthesia and an oesophagostomy tube was placed. The scan revealed the presence of multiple right tympanic bulla fractures. Multiple mandibular, maxillary, and palatine fractures were also present. The cat underwent surgery. Mandibular symphyseal separation and maxillary fractures were stabilized using intraoral cerclage wire fixation reinforced with composite and the right eye was enucleated. The rest of the fractures were treated conservatively. A CT scan 4 months after the trauma was also performed. At this point, the maxillofacial fractures were healing properly, and a bone callus demonstrating fusion of fragments of the right tympanic bulla was evident. There was absence of abnormal content inside the right tympanic bulla. The patient recovered uneventfully with no neurological deficits. To the author's knowledge this is the first case reporting a traumatic tympanic bulla fracture in the cat with case follow up, and the first case reported using CT as diagnostic imaging test.