The effect of direction of force to the craniofacial skeleton on the severity of brain injury in patients with a fronto-basal fracture

Head injury: Importance of the deep brain nuclei in force transmission to the brain

Finite element modeling provides a digital representation of the human body. It is currently the most pertinent method to study the mechanisms of head injury, and is becoming a scientific reference in forensic expert reports. Improved biofidelity is a recurrent aim of research studies in biomechanics in order to improve earlier models whose mechanical properties conformed to simplified elastic behavior and mechanic laws. We aimed to study force transmission to the brain following impacts to the head, using a finite element head model with increased biofidelity. To the model developed by the Laboratory of Applied Biomechanics of Marseille, we added new brain structures (thalamus, central gray nuclei and ventricular systems) as well as three tracts involved in the symptoms of head injury: the corpus callosum, uncinate tracts and corticospinal tracts. Three head impact scenarios were simulated: an uppercut with the prior model and an uppercut with the improved model in order to compare the two models, and a lateral impact with an impact velocity of 6.5 m/s in the improved model. In these conditions, in uppercuts the maximum stress values did not exceed the injury risk threshold. On the other hand, the deep gray matter (thalamus and central gray nuclei) was the region at highest risk of injury during lateral impacts. Even if injury to the deep gray matter is not immediately life-threatening, it could explain the chronic disabling symptoms of even low-intensity head injury.

Concussion in facial trauma patients: a retrospective analysis of 100 patients from a UK major trauma centre

Concussion is a common and potentially debilitating condition. Research has shown that one-third of patients admitted with facial trauma have concurrent concussion. This study aimed to investigate the burden and management of concussion in patients presenting with acute facial trauma, and to identify potential risk factors within this population. A retrospective observational study was conducted at a UK major trauma centre between 1 January 2019 and 1 February2020. One hundred randomly selected patients who attended the acute clinic responsible for managing facial trauma were identified. No parametric data were included. The Mann-Whitney test was used to detect differences for continuous data, the X2 test for categorical data. Clinical significance was defined as p < 0.05. Forty of 100 patients (40%) had evidence of concussion, of which only 4/40 (10%) had evidence that head injury advice had been given. There was no statistically significant difference between the non-concussed and concussed groups for age (p = 0.145), gender (p = 0.921), mechanism of injury (p = 0.158), or location of facial injury (p = 0.451). Clinical features of concussion were found in 40% of patients suffering from facial injury. Despite this, we found that head injury advice was rarely given. In addition, we identified no risk factors for concussion within this population, highlighting the need to screen all patients who present with facial injury. To improve the identification and management of concussion in these patients, future work should focus on the development of simple screening tools for use in clinic, and the signposting of patients to existing written and online concussion resources.

Role of the Maxillofacial Surgeon in Identifying the Correlation Between Facial Bone Fractures and Traumatic Brain Injury - A Prospective Study

Introduction

Maxillofacial trauma accounts for a high percentage of patients reporting to the emergency medicine department and being admitted in the hospital. The purpose of this study was to form a direct association between maxillofacial fractures and traumatic brain injury (TBI).

Methods

Ninety patients with maxillofacial fractures that reported to/were referred to the Department of Oral and Maxillofacial Surgery were observed for features indicative of TBI based on clinical presentation and radiological interpretations. Parameters such as loss of consciousness, vomiting, dizziness, headache, seizures and the requirement for intubation, cerebrospinal fluid rhinorrhoea and otorrhoea were also assessed. Appropriate radiographs for the diagnosis of the fracture were taken followed by a computed tomography (CT) scan when indicated in accordance to the Canadian CT Head Rule. These scans were then assessed for contusion, extradural haemorrhage, subdural haemorrhage, subarachnoid haemorrhage, pneumocephalus and cranial bone fracture.

Results

A total of 90 patients were evaluated, of which 91.1% were males and 8.9% were females. Association between the occurrence of head injury and different maxillofacial bone fractures using the Chi-square test showed a statistical significance of <0.001 in patients with naso-orbito-ethmoid as well as frontal bone fractures. There was a clear association between fractures present in the upper as well as the middle third of the face and traumatic head injury (P ≤ 0.001).

Discussion

Patients with the frontal bone and zygomatic bone fractures have a high prevalence of TBI. Patients with the upper and middle third of the face injury are more prone to traumatic head injury and importance should be given to patients with the same and prevent poor prognosis.

Mathematical analysis of fracture configuration in predicting outcome in complex anterior skull base trauma

Craniofacial trauma involving the anterior skull base produces a heterogenous injury with variance in fracture pattern, complexity and outcome. Variance is influenced by the biomechanical properties of the craniofacial construct and by the magnitude and vector of the impacting energy. Fractal dimension and other metrics applied to individual fracture patterns allows quantification of fracture complexity and severity, which can be used to correlate with neurological outcome. Frontobasal fractures from 81 patients admitted to two UK major trauma centres were analysed. Patients were divided into two groups: those with anteriorly-based vectors of impact and those with laterally-based vectors. Osseous disruption was quantified by: fractal dimension, fracture length, number of termini, and number of nodes, and then compared with neurological outcome using first recorded Glasgow Coma Score (GCS), and requirement for intubation. As fracture length increased, fractures from anterior impacts became more complex and reticulated compared with lateral impacts; fractal dimension also increased more rapidly for anterior impacts. Longer fracture length in both groups was associated with a significantly lower GCS, and increased requirement for intubation (p < 0.001 and p < 0.001 respectively). Fracture propagation and severity of head injury was different in anterior-directed trauma compared to lateral-directed trauma. Consequently, we suggest that the central region of the anterior skull base acts to primarily absorb impact force thereby behaving as a protective ' crumple zone ' . In severe mechanisms the protective mechanism is exceeded and the fracture length tended to that of the lateral group worsening prognosis.

Imaging of Skull Base Trauma: Fracture Patterns and Soft Tissue Injuries

This article provides an overview of the patterns of skull base trauma and provides a review of the pertinent soft tissue injuries and complications that can ensue. A brief review of skull base anatomy is provided with subsequent focus on the important findings in anterior, central, and posterior skull base trauma.

Surgical Treatment and Visual Outcomes of Adult Orbital Roof Fractures

BACKGROUND

Fractures of the orbital roof require high-energy trauma and have been linked to high rates of neurologic and ocular complications. However, there is a paucity of literature exploring the association between injury, management, and visual prognosis.

METHODS

The authors performed a 3-year retrospective review of orbital roof fracture admissions to a Level I trauma center. Fracture displacement, comminution, and frontobasal type were ascertained from computed tomographic images. Pretreatment characteristics of operative orbital roof fractures were compared to those of nonoperative fractures. Risk factors for ophthalmologic complications were assessed using univariable/multivariable regression analyses.

RESULTS

In total, 225 patients fulfilled the inclusion criteria. Fractures were most commonly nondisplaced [n = 118 (52.4 percent)] and/or of type II frontobasal pattern (linear vault involving) [n = 100 (48.5 percent)]. Eight patients underwent open reduction and internal fixation of their orbital roof fractures (14.0 percent of displaced fractures). All repairs took place within 10 days from injury. Traumatic optic neuropathy [n = 19 (12.3 percent)] and retrobulbar hematoma [n = 11 (7.1 percent)] were the most common ophthalmologic complications, and led to long-term visual impairment in 51.6 percent of cases.

CONCLUSIONS

Most orbital roof fractures can be managed conservatively, with no patients in this cohort incurring long-term fracture-related complications or returning for secondary treatment. Early fracture treatment is safe and may be beneficial in patients with vertical dysmotility, globe malposition, and/or a defect surface area larger than 4 cm2. Ophthalmologic prognosis is generally favorable; however, traumatic optic neuropathy is major cause of worse visual outcome in this population.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Measurement and Finite Element Model Validation of Immature Porcine Brain-Skull Displacement during Rapid Sagittal Head Rotations

Computational models are valuable tools for studying tissue-level mechanisms of traumatic brain injury, but to produce more accurate estimates of tissue deformation, these models must be validated against experimental data. In this study, we present in situ measurements of brain-skull displacement in the neonatal piglet head (n = 3) at the sagittal midline during six rapid non-impact rotations (two rotations per specimen) with peak angular velocities averaging 51.7 ± 1.4 rad/s. Marks on the sagittally cut brain and skull/rigid potting surfaces were tracked, and peak values of relative brain-skull displacement were extracted and found to be significantly less than values extracted from a previous axial plane model. In a finite element model of the sagittally transected neonatal porcine head, the brain-skull boundary condition was matched to the measured physical experiment data. Despite smaller sagittal plane displacements at the brain-skull boundary, the corresponding finite element boundary condition optimized for sagittal plane rotations is far less stiff than its axial counterpart, likely due to the prominent role of the boundary geometry in restricting interface movement. Finally, bridging veins were included in the finite element model. Varying the bridging vein mechanical behavior over a previously reported range had no influence on the brain-skull boundary displacements. This direction-specific sagittal plane boundary condition can be employed in finite element models of rapid sagittal head rotations.