Efficacy of MRI for assessment of spinal trauma: correlation with intraoperative findings.

STUDY DESIGN: Observational diagnostic study on consecutive patients. OBJECTIVE: To assess the efficacy of magnetic resonance imaging (MRI) for detecting spinal soft tissue injury after acute trauma using intraoperative findings as a reference standard. SUMMARY OF BACKGROUND DATA: Recognizing injuries to spinal soft tissue structures is critical for proper decision making and management for blunt trauma victims. Although MRI is considered the gold standard for imaging of soft tissues, its ability to identify specific components of soft tissue damage in acute spine trauma patients is poorly documented and controversial. METHODS: Intraoperative findings were recorded for 21 acute spinal trauma patients (study group) and 14 nontraumatic spinal surgery patients (control group). Preoperative MRI's were evaluated randomly and blindly by 2 neuroradiologists. MRI and intraoperative findings were compared. By using the intraoperative findings as the reference standard, sensitivity, specificity, positive and negative predictive values of MRI in detecting spinal soft tissue injury were determined. RESULTS: MRI was 100% sensitive and specific in detecting injury to the anterior longitudinal ligament. MRI was moderately sensitive (80%) but highly specific (100%) for injury to the posterior longitudinal ligament. In contrast, MRI was highly sensitive but less specific in detecting injury to paraspinal muscles (100%, 77%), intervertebral disk (100%, 71%), and interspinous ligament (100%, 64%). MRI was moderately sensitive and specific in detecting ligamentum flavum injury (80% and 86.7%) but poorly sensitive for facet capsule injury (62.5%). CONCLUSIONS: MRI demonstrated high sensitivity for spinal soft tissue injuries. However, MRI showed a definite trend to overestimate interspinous ligament, intervertebral disk, and paraspinal muscle injuries. On the basis of these results, we would consider MRI to be a useful tool for spine clearance after trauma. Conversely, caution should be applied when using MRI for operative decision making due to its less predictable specificity.

A cadaver study to compare vertebral augmentation with a high-viscosity cement to augmentation with conventional lower-viscosity cement.

STUDY DESIGN: Comparison of extravasations in fractured cadaver vertebrae augmented with commercial low-viscosity versus high-viscosity cements. OBJECTIVE: Use of high-resolution, 3-dimensional (3D) imaging to test the hypothesis that high-viscosity cements can reduce the type and severity of extravasations after vertebral augmentation procedures. SUMMARY OF BACKGROUND DATA: Cement extravasations are one of the primary complications of vertebral augmentation procedures. There is some evidence that high-viscosity cements might reduce extravasations, but additional data are needed to confirm the early findings. METHODS: A range of vertebral fractures were created in fresh human cadavers. One group was then augmented with a low-viscosity polymethylmethacrylate (PMMA)-based cement and the other group injected with high-viscosity PMMA-based cement. High-resolution computerized tomography exams were obtained, and extravasations were assessed using 3D volume renderings. The type and severity of extravasations were recorded and analyzed. RESULTS: The proportion of vertebrae with any type of extravasation through the posterior wall to the spinal canal, into small vessels laterally or anteriorly, through the endplates, or anywhere around the body was not significantly different between the high-viscosity and low-viscosity groups. There was significantly less severe extravasation through the endplates (P=0.02), and a trend toward less severe extravasation through vessels (P=0.06) with the high versus low-viscosity cements. CONCLUSIONS: In agreement with previous research, high-viscosity PMMA-based cement may help to reduce the more severe forms of extravasations after vertebral augmentation procedures in newly fractured vertebrae.

Motion within the unstable cervical spine during patient maneuvering: the neck pivot-shift phenomenon.

BACKGROUND: Cervical extrication collars are applied to millions of blunt trauma victims despite the lack of any evidence that a collar can protect against secondary injuries to the cervical spine. Cadaver studies support that in the presence of a dissociative injury, substantial motion can occur within the occipitocervical spine with collar application or during patient transfers. Little is known about the biomechanics of cervical stabilization; hence, it is difficult to develop and test improved immobilization strategies. MATERIALS: Severe unstable injuries were created in seven fresh whole human cadavers. Rigid collars were applied with the body in a neutral position. Computed tomographic examinations were obtained before and after tilting the body or backboard as would be done during patient transport or to inspect the back. Relative displacements between vertebrae at the site of the injury were measured from the Computed tomographic examinations. The overall relative alignment between body and collar was assessed to understand the mechanisms that may facilitate motion at the injury site. RESULTS: Intervertebral motion averaged 7.7 mm±6.8 mm in the axial plain and 2.9 mm±2.5 mm in the cranial-caudal direction. The rigid collars appeared to create pivot points where the collar contacts the head in the region under the ear and where the collar contacts the shoulders. DISCUSSION: Rigid cervical collars appear to create pivot points that shift the center of rotation lateral to the spine and contribute to the intervertebral motions that were measured. Immobilization strategies that avoid these neck pivot-shift phenomena may help to reduce secondary injuries to the cervical spine. The whole cadaver model with simulation of patient maneuvers may provide an effective test method for cervical immobilization.

Diagnosis of unstable cervical spine injuries: laboratory support for the use of axial traction to diagnose cervical spine instability.

BACKGROUND: The ability to detect damage to the intervertebral structures is critical in the management of patients after blunt trauma. A practical and inexpensive method to identify severe structural damage not clearly seen on computed tomography would be of benefit. The objective of this study was to assess whether ligamentous injury in the subaxial cervical spine can be reliably detected by analysis of lateral radiographs taken with and without axial traction. METHODS: Twelve fresh, whole, postrigor-mortis cadavers were used for this study. Lateral cervical spine radiographs were obtained during the application of 0 N, 89 N, and 178 N of axial traction applied to the head. Progressive incremental sectioning of posterior structures was then performed at C4-C5 with traction imaging repeated after each intervention. Intervertebral distraction was analyzed using computer-assisted software. RESULTS: Almost imperceptible intervertebral separation was found when traction was applied to intact spines. In the subaxial cervical spine, the average posterior disc height consistently increased under traction in severely injured spines. The average disc height increase was 14% of the C4 upper endplate width, compared with an average of 2% in the noninjured spines. A change of more than 5% in posterior disc height under traction was above the 95% confidence interval for intact spines, with sensitivity of 83% and specificity of 80%. Applied force of 89 N (20 lb) was sufficient to demonstrate injury. The combination of assessing alignment and distraction under traction increased both the sensitivity and specificity to nearly 100%. CONCLUSION: This study supports further clinical investigations to determine whether low-level axial traction may be a useful adjunct for detecting unstable subaxial cervical spine injuries in an acute setting.

Extrication collars can result in abnormal separation between vertebrae in the presence of a dissociative injury.

BACKGROUND: Cervical collars are applied to millions of trauma victims with the intent of protecting against secondary spine injuries. Adverse clinical outcomes during the management of trauma patients led to the hypothesis that extrication collars may be harmful in some cases. The literature provides indirect support for this observation. The purpose of this study was to directly evaluate cervical biomechanics after application of a cervical collar in the presence of severe neck injury. METHODS: Cranial-caudal displacements in the upper cervical spine were measured in cadavers from images taken before and after application of collars following creation of an unstable upper cervical spine injury. RESULTS: In the presence of severe injury, collar application resulted in 7.3 mm +/- 4.0 mm of separation between C1 and C2 in a cadaver model. In general, collars had the effect of pushing the head away from the shoulders. CONCLUSIONS: This study was consistent with previous evidence that extrication collars can result in abnormal distraction within the upper cervical spine in the presence of a severe injury. These observations support the need to prioritize additional research to better understand the risks and benefits of cervical stabilization methods and to determine whether improved stabilization methods can help to avoid potentially harmful displacements between vertebrae.

Direct transoral manipulation to reduce a displaced odontoid fracture: a technical note.

BACKGROUND CONTEXT: Irreducible anteriorly displaced odontoid fractures are usually treated with posterior atlantoaxial fusion. PURPOSE: To present an alternative for fracture reduction and anterior stabilization for displaced odontoid fractures. STUDY DESIGN: A technique for reduction of odontoid fractures is reported. PATIENT SAMPLE: Case study of a single patient with an odontoid fracture. OUTCOME MEASURES: Only fracture reduction and fracture healing were evaluated. METHODS: After a failed trial of closed reduction with skeletal traction, a patient with an anteriorly displaced odontoid fracture was taken to the operating room for attempted closed reduction and odontoid screw placement. RESULTS: Fracture reduction was achieved with routine maneuvers supplemented by posterior translation through direct oropharyngeal pressure with a padded laryngoscope blade. CONCLUSIONS: Direct transoral reduction of odontoid fractures is safe and feasible and can be used to assist in reduction of anteriorly displaced fractures.

Intrathecal migratory foreign body without neurological deficit after a gunshot wound.

BACKGROUND CONTEXT: Penetrating bullets dissipate thermal and kinetic energy into surrounding tissues. Within the thecal sac, this is universally associated with neurological deficits. PURPOSE: We report a case of intrathecal penetration of a bullet without neurological deficit. STUDY DESIGN: Case report. METHODS: A 14-year-old girl was shot in the back, entering adjacent to the L3 vertebra and settling within the spinal canal adjacent to the S1 vertebra. In the absence of neurological deficits, initial management was nonoperative. RESULTS: Over the period of a week, the patient developed an episode of intense radicular pain, although her neurological examination remained normal. Location of the bullet was shown to vary from S1 to T12 on multiple imaging studies, and this was influenced by patient positioning. She subsequently underwent a bilateral hemilaminotomy and durotomy with excision of the intrathecal bullet. CONCLUSIONS: Patients can avoid neurological injury even with an intrathecal gunshot wound. However, intrathecal bullets may then migrate and cause variable neurological complaints, necessitating surgical removal. Patient positioning can influence bullet location which can be useful in surgical planning.

Antibiotic-Resistant Spondylodiscitis With Canal Invasion and Aggressive Evolution to Epidural Abscess: A Case Series of Spontaneous Occurrence in 16 Patients.

BACKGROUND: The study aimed to assess the effectiveness of antibiotic treatment for spondylodiscitis, its failure rates, and the need for surgical intervention. METHODS: This is a retrospective study of patients who presented with spontaneous deep spinal infections and spondylodiscitis between 2011 and 2013. Clinical, bacteriologic, and radiographic data during hospitalization were analyzed. RESULTS: A total of 16 patients presented with deep spinal infections during the study period; 15 of them presented with spontaneous pyogenic spondylodiscitis, and 1 presented with epidural abscess. Median age was 68 years (range, 50-80 years), and 6 (38%) were healthy young laborers. None of the patients were immunocompromised. On admission all patients presented with pain, there was fever in 3 patients (19%), and there was elevated blood C-reactive protein, white blood cell count and erythrocyte sedimentation rate, with a mean of 147 ± 83.1 mg/L, 11.65 ± 5.6 × 103/µL, 93.6 ± 35.1 mm/h, respectively. A total of 15 patients (94%) developed infections that were refractory to appropriate culture-specific intravenous antibiotic treatment (mean, 10.2 days); 8 patients (50%) deteriorated neurologically and required wide surgical decompression. Complications included widespread epidural free gas in 2 patients (12%), multiple bilateral psoas abscesses in 2 patients (12%), kyphotic segmental instability in 4 patients (25%), and inferior vena cava septic thrombi in 1 patient (6%). A total of 3 patients (19%) died within 6 months; 7 of 13 surviving patients still had residual neurologic deficits at the 6-month follow-up. CONCLUSIONS: Spondylodiscitis may be resistant to antibiotic treatment and may evolve into epidural abscess via extension of the infection and pus into the spinal canal, necessitating repetitive surgical treatment due to neurologic and clinical deterioration, and expansion of the persistent infection with a mass effect. Increased vigilance for this condition and its misleading initial presentations is warranted.

The distended facet sign: an indicator of position-dependent spinal stenosis and degenerative spondylolisthesis.

BACKGROUND CONTEXT: Symptoms of spinal stenosis are position-dependent. Stand up magnetic resonance imaging (MRI) and myelography can demonstrate further dynamic components of spinal stenosis that may go unrecognized on supine MRI. PURPOSE: To describe a radiographic finding seen on standard supine MRI that is an indicator for dynamic spinal stenosis and degenerative spondylolisthesis. STUDY DESIGN/SETTING: Case series. PATIENT SAMPLE: Six patients. OUTCOMES MEASURES: Radiographic observation. METHODS: Six patients with classic neurogenic claudication but equivocal supine MRI findings were evaluated with myelography. The imaging findings were reviewed and compared. RESULTS: All patients had severe position-dependent spinal stenosis upon upright myelographic imaging with grade I or II spondylolisthesis. The MRI showed very minimal to no spondylolisthesis. These dynamic slips reduced when supine, causing the vertebral bodies to appear aligned with adequate canal space, whereas the irregular facet joints became distended. Hypertrophic and fluid-filled facets at the dynamic slip level were seen in all patients, giving the appearance of a distended joint. CONCLUSIONS: MRI may not demonstrate significant stenosis in patients with neurogenic claudication caused by dynamic degenerative spondylolisthesis. However, the presence of large fluid-filled facet joints indicates the likelihood of positional translation at that level which could be further confirmed by upright imaging.

Cervical spine injuries in civilian victims of explosions: Should cervical collars be used?

BACKGROUND: Semirigid cervical collars (SRCCs) are routinely applied to victims of explosions as part of the prehospital trauma protocols. Previous studies have shown that the use of SRCC in penetrating injuries is not justified because of the scarcity of unstable cervical spine injuries and the risk of obscuring other neck injuries. Explosion can inflict injuries by fragments penetration, blast injury, blunt force, and burns. The purpose of the study was to determine the occurrence of cervical spine instability without irreversible neurologic deficit and other potentially life-threatening nonskeletal neck injuries among victims of explosions. The potential benefits and risks of SRCC application in explosion-related injuries were evaluated. METHODS: This is a retrospective cohort study of all explosion civilian victims admitted to Israeli hospitals during the years 1998 to 2010. Data collection was based on the Israeli national trauma registry and the hospital records and included demographic, clinical, and radiologic details of all patients with documented cervical spine injuries. RESULTS: The cohort included 2,267 patients. All of them were secondary to terrorist attacks. SRCC was applied to all the patients at the scene. Nineteen patients (0.83%) had cervical spine fractures. Nine patients (0.088%) had unstable cervical spine injury. All but one had irreversible neurologic deficit on admission. A total of 151 patients (6.6%) had potentially life-threatening penetrating nonskeletal neck injuries. CONCLUSION: Unstable cervical spine injuries secondary to explosion are extremely rare. The majority of unstable cervical spine fractures were secondary to penetrating injuries, with irreversible neurologic deficits on admission. The application of SRCC did not seem to be of any benefit in these patients and might pose a risk of obscuring other neck injuries. We recommend that SRCC will not be used in the prehospital management of victims of explosions. LEVEL OF EVIDENCE: Prognostic/epidemiologic study, level III.

Extra-peritoneal pressure packing without external pelvic fixation: A life-saving stand-alone surgical treatment.

PURPOSE: Traditional maneuvers aim to decrease retroperitoneal bleeding in hemodynamically unstable multi-trauma patients with unstable pelvic fractures, are reportedly successful in approximately only 50%. The life-saving effect of extra-peritoneal pressure packing (EPPP) is based on direct compression and control of both venous and arterial retroperitoneal bleeders. This study describes the safety and efficacy of emergent EPPP employment, as a stand-alone surgical treatment, that is, carried out without external pelvic fixation or emergent angiography. MATERIALS AND METHODS: A retrospective chart review of all hemodynamic unstable, multi-trauma patients with mechanically unstable pelvic fractures treated by the EPPP technique at our medical center between the years 2005 and 2011. Survival rates, clinical, and physiological outcomes were followed prospectively. RESULTS: Twenty-five of the 181 pelvic fracture patients had biomechanically unstable fractures that required surgical fixation. Fourteen of those 25 patients had deteriorating hemodynamic instability from massive pelvic bleeding which was resistant to resuscitation, and they underwent EPPP, as a stand-alone treatment. The procedure successfully achieved hemodynamic stability in all 14 patients and obviated the early mortality associated with massive pelvic bleeding. Three of these patients eventually succumbed to their multiple injuries. CONCLUSION: Implementation of EPPP improved all measured physiological outcome parameters and survival rates of hemodynamically unstable multi-trauma patients with unstable pelvic fractures in our trauma center. It provided the unique advantage of directly compressing the life-threatening retroperitoneal bleeders by applying direct pressure and causing a tamponade effect to stanch venous and arterial pelvic blood flow and obviate the early mortality associated with massive pelvic bleeding.

Intradural Extension of a Pyogenic Epidural Abscess: A Case Report.

CASE: Few cases of spinal epidural abscess involving an extradural abscess with an intradural extension have been reported. A unique complication with extension of pus from the epidural space through multiple perforations into the dura is described. Due to a proximal meningeal inflammatory reaction, which served as a proximal plug, no cerebrospinal fluid leak was encountered. CONCLUSION: Intradural extension of pus through multiple dural perforations is a rare complication of spinal epidural abscess and a treatment challenge. Early diagnosis enabling prompt surgical decompression, along with subsequent aggressive debridements and prolonged intravenous antibiotic treatment, can lead to a favorable outcome.

Low-back pain, lassitude and loss of appetite.

White blood cells, Erythrocyte sedimentation rate and C-reactive protein are sensitive tools to discover rare, but potentially serious pyogenic vertebral osteomyelitis, a disease whose incidence is increasing.

Reference data for interpreting widening between spinous processes in the lumbar spine.

BACKGROUND CONTEXT: Traumatic injury to the lumbar spine is evaluated and treated based on the perceived stability of the spine. Recent classification schemes have established the importance of evaluating the posterior ligamentous complex (PLC) to fully comprehend stability. There are a variety of techniques to evaluate the PLC, including assessment of interspinous distance. However reference data to define normal widening are poorly developed. PURPOSE: Define normal interspinous widening in the lumbar spine. STUDY DESIGN: Biomechanical and observational. To establish reference data for asymptomatic population and use the reference data to suggest criteria for routine clinical practice to be validated in future studies. METHODS: Interspinous distances were measured from lateral lumbar X-rays of 157 asymptomatic volunteers. Measurements from the asymptomatic population were used to define normal limits and create a simple screening tool for clinical use. Distances were calculated from the relative position of landmarks at each intervertebral level. The distances were normalized to the anterior-posterior width of the superior end plate of L3. The change in interspinous process distance from flexion to extension was calculated, and the change in interspinous widening between flexion and extension with respect to widening at the adjacent levels was also calculated. RESULTS: Seven hundred seventy-two thoracolumbar levels were available for analysis. The observed interspinous motion was slightly more than the interlaminar motion. However, the tips of the spinous processes were more difficult to identify in some images, so the interlaminar line distances were considered more reliable. Significant difference in interlaminar distances was not found between levels. The upper limit (UL) of normal spacing measured between the interlaminar lines was approximately 85% of the L3 end plate width at all levels except L5-S1, which was 105%. The UL of normal for interlaminar displacements between flexion and extension was 30% of the L3 end plate width at L1-L2 to L4-L5 and 40% at L5-S1. CONCLUSIONS: This study provides normative data and methods that can be used in developing guidelines to objectively assess interspinous process widening. Simple rules can be applied to quickly assess interspinous widening. Additional research is required to validate these guidelines. A simple measurement such as spinous process widening is unlikely to be proven as an isolated clinically effective screening test but combining that with other patient evaluation's screening modalities may prove to be a sensitive evaluation protocol for the screening of injuries to the PLC.

Toward the establishment of optimal computed tomographic parameters for the assessment of lumbar spinal fusion.

BACKGROUND CONTEXT: The accurate detection of the extent of bony fusion after attempted lumbar arthrodesis is important given that subsequent efforts-such as decisions regarding need for continued external bracing, use of enhancing modalities (electrical stimulation and pulsed ultrasound), recommended activity levels, return to employment, early surgical intervention, and others-may be needed to reduce the risk of late failure, especially in light of the fact that late revisions for failed fusions often result in poor outcomes and significant costs. Thin-cut computed tomography (CT) has emerged as the study of choice for this purpose. PURPOSE: To delineate the optimal CT parameters for determining fusion versus pseudarthosis after attempted lumbar fusion. STUDY DESIGN: Blinded CT assessment with cadaveric specimen as a gold standard. METHODS: A human cadaveric spine specimen with a T10 to S1 thoracolumbar posterolateral fusion augmented by instrumentation and anterior lumbar interbody fusions was used as a gold standard. Two experienced spine surgeons and one musculoskeletal radiologist-all blinded to the pathology results-assessed a series of CT scans of the specimen, each CT using one of six predefined sets of parameters. RESULTS: Predictive values and sensitivity generally improved with decreasing slice thickness and slice spacing, but only modestly. All sets of parameters had higher negative predictive value (NPV) than positive predictive value (PPV). Computed tomographic parameters of 0.9-mm thick sections with 50% overlap showed the highest PPV and NPV, where NPV was 90, but PPV was only 59. CONCLUSIONS: In this study, using the best widely available CT technologies and the ideal gold standard, thin-cut CT remained less than ideal for the assessment of lumbar arthrodesis/pseudarthrosis. Tuning slice thickness and slice spacing down generally improves detail, but marginally. We have successfully defined "optimal" as "best available," but "optimal" as "nearly perfect" awaits further technological advances.

A pictorial classification atlas of cement extravasation with vertebral augmentation.

BACKGROUND CONTEXT: Minimally invasive procedures for the treatment of vertebral compression fractures (VCFs) have been in use since the mid-1980s. A mixture of liquid monomer and powder is introduced through a needle into one or both pedicles, and it polymerizes within the vertebral body in an exothermic chemical reaction. The interaction between cement and the fractured vertebral body determines whether and how the cement stabilizes the fragments, alters morphology, and extravasates. The cement is intended to remain within the vertebral body. However, some studies have reported cement leakage in more than 80% of the procedures. Although cement leakage can have no or minimal clinical consequences, adverse events, such as paraplegia, spinal cord and nerve root compression, cement pulmonary embolisms, or death, can occur. The details of how the cement infiltrates a vertebral body or extravasates out of the body are poorly understood and may help to identify strategies to reduce complications and improve clinical efficacy. PURPOSE: Apply novel techniques to demonstrate the cement spread inside vertebrae as well as the points and pattern of cement extravastation. STUDY DESIGN: Ex vivo assessment of vertebral augmentation procedures. METHODS: Vertebrae from six fresh whole human cadaver spines were used to create 24 specimens of three vertebrae each. The specimens were placed in a pneumatic testing system, designed to create controlled anterior wedge compression fractures. Unipedicular augmentation was performed on the central vertebra of 24 specimens using polymethylmethacrylate/barium sulfate Vertebroplastic cements (DePuy Spine, Raynham, MA, USA). The volume of cement injected into each vertebra was recorded. Fine-cut computed tomography (CT) scans of all segments were obtained (Brilliance 64; Philips Medical Imaging, Amsterdam, The Netherlands). Using multiplanar reconstructions and volume compositing three-dimensional imaging (Osirix, www.osirix-viewer.com), each specimen was carefully assessed for cement extravasation. Specimens were then immersed in a 50% sodium hypochlorite solution until all overlying soft tissues were removed, leaving the bone and cement intact. The specimens were dried and visually examined and photographed to assess cement extravasation and fracture patterns. Specimens were cut in the axial or sagittal plains to assess the gross morphology of cement infiltration and extravasation. Finally, 25-mm block sections were removed from selected specimens and imaged at 14-µm resolution using a GE Locus-SP micro-CT system (GE Healthcare, London, Ontario, Canada). RESULTS: Infiltration was characterized by an intimate capture of trabecular bone within the cement, forming an irregular border at the perimeter of the cement that is determined by the morphology of the trabeculae and marrow spaces. Extravasation of the cement was assessed as "any" if any small or large amount of extravastation was detected and was also assessed as severe if a large amount of extravasation was found. Out of the 23 levels studied, some extravasation was visibly apparent in all levels. A wide spectrum of filling patterns, leakage points, and interdigitation of the cement was observed and appeared to be determined by the interaction of the cement with the trabecular morphology. The results support the fact that the cement generally advances through the vertebrae with relatively regular and easily identifiable borders. CONCLUSIONS: Using a cadaver VCF model, this study demonstrated the exact filling and extravastation patterns of bone cement inside and out of fractured vertebrae. These data enhance our understanding of the vertebral augmentation and extravastation mechanics.

The association of occipitocervical dissociation and death as a result of blunt trauma.

BACKGROUND CONTEXT: Despite multiple reports of survivability, dissociative occipitocervical injury (OCI) is generally accepted to be fatal in most cases. The actual number of trauma victims where OCI may have made the difference between life and death is unknown because multiple studies have shown that these injuries can be missed with current diagnostic methods. An improved understanding of the relative importance of OCI in blunt trauma mortality may help to refine protocols for the assessment and treatment of patients who arrive alive to the emergency room after severe blunt trauma. One way to improve our understanding is to document the relative frequency OCI relative to brain, liver, aorta, and spleen injuries in blunt trauma fatalities. PURPOSE: In this study, we aimed to glean a more accurate estimate of the absolute and relative incidence of OCI after death from blunt trauma via a systematic review of data reported in the forensic literature. STUDY DESIGN: Systematic literature review. METHODS: A systematic literature search and review were undertaken. The search aimed to answer three primary questions: What is the true incidence of cervical spine injuries in blunt trauma fatalities? What is the incidence of dissociative OCIs specifically? and What is the incidence of these injuries relative to other common injuries associated with blunt trauma fatalities (central nervous system, spleen, liver, etc)? For that, two search protocols were used and included postmortem studies of blunt trauma mechanism in adult population. RESULTS: The mean reported incidence of cervical spine injuries was 49.7% in blunt trauma fatalities. Dissociative OCIs were found to have a mean incidence of 18.1%. The relative frequencies of injuries were 49.7% for cervical spine, 41.8% for central nervous system, 20.8% for liver, 11.2% for spleen, and 10.8% for aorta. CONCLUSIONS: In this systematic literature review, cervical spine injuries were found to be the most commonly reported finding associated with blunt trauma fatalities, occurring in nearly 50% of cases with occipitocervical dissociation accounting for nearly 20%. Older pathologic studies suggested a lesser overall and relative frequency and may have underestimated their incidence. Typically, these blunt cervical spine injuries were much more commonly found to disrupt the soft tissue stabilizing restraints (ligaments, facet capsules, etc) as opposed to causing bony fractures and, accordingly, were often not detected on plain radiographs. It is likely that the frequency of this injury is underestimated in patients surviving severe blunt trauma, placing them at risk for death from an occult source in the postinjury period. Additional research is needed to determine if improved methods to diagnose OCI and improved patient management protocols to protect against secondary injuries might reduce mortality in blunt trauma victims.

Occipitocervical dissociative injuries: common in blunt trauma fatalities and better detected with objective computed tomography-based measurements.

BACKGROUND CONTEXT: Occipitocervical injuries (OCIs) are generally not common in blunt trauma victims, but autopsy studies of blunt trauma fatalities consistently report a high prevalence of these injuries. New computed tomography (CT)-based quantitative criteria have recently been developed for use in assessing the occipitocervical spine. The efficacy of these new criteria for detecting OCI would be supported if the high prevalence of OCI in blunt trauma fatalities can also be detected using these objective CT-based criteria. PURPOSE: To test the hypothesis that the prevalence of OCI in blunt trauma fatalities, determined using objective CT-based measurements and reliable reference data, will be similar to the prevalence reported in prior autopsy studies. STUDY DESIGN/SETTING: Retrospective assessment of the CT examinations of blunt trauma fatalities at a Level 1 trauma center. PATIENT SAMPLE: Seventy-four consecutive patients who died within 21 days of blunt trauma and had a CT examination of the cervical spine. OUTCOME MEASURES: Quantitative measurements from CT examinations of the occiput-C1 and C1-C2 levels. METHODS: Measurements were made on a Picture Archiving and Communication System (PACS) from the CT images that were originally used for diagnosis and also using imaging software that allowed for precisely reoriented slices that correct for variations in the alignment of the upper cervical spine. The prevalence of abnormal measurements found by each method and the interobserver reliability of the measurements were assessed. RESULTS: At least one abnormal measurement was found in 50% of cases based on measurements made on the PACS, and in 34% of cases using measurements from carefully reoriented images. At least three abnormal measurements were found in 22% and 14% of patients, respectively. Only one of the patients had been diagnosed as having an OCI before death. Interobserver reliability measurements of more than 80% were found for most measurements. CONCLUSIONS: Using precise CT-based measurements and reliable reference data for diagnosis of occipitocervical dissociative injuries, the prevalence of injuries in severely injured blunt trauma patients was close to the levels reported in prior autopsy studies (approximately 30%). This supports that with careful measurements, both soft- and hard-tissue OCI can be detected by CT. This study is limited by the fact that a gold standard was not available to confirm the injuries.

Comprehensive computed tomography assessment of the upper cervical anatomy: what is normal?

BACKGROUND CONTEXT: High-speed computed tomography (CT) exams have replaced traditional radiographs for assessment of cervical spine injuries in many emergency departments. Recent evidence demonstrates that even subtle displacements can indicate significant upper cervical spine injuries. Many different anatomical measurements have been described in the upper cervical spine to date, most of them based on X-ray. The range of anatomical relationships that exist in an uninjured population must be known to reliably detect abnormal relations. The measurements with the lowest normal variation are likely to be most useful in detecting injuries. PURPOSE: The purpose of this study was to describe the normal quantitative anatomical relationships as well as the threshold measurements most likely to detect injury in the upper cervical spine. STUDY DESIGN/SETTING: Retrospective anatomical case review. PATIENT SAMPLE: Seventy-six thin-sliced cervical CT scans randomly selected from a trauma population, all negative for injury in the cervical spine. METHODS: Forty-two different anatomical measurements were made of the upper cervical spine. These included traditional historical measurements and other detailed dimensions to characterize occipitocervical (OC) and atlantoaxial (AA) joint relationships. RESULTS: After review of all the anatomical measurements performed in the upper cervical spine, direct measurements of the joint space had the least variation. The mean OC joint space was 0.6mm, with an upper 95% confidence interval (CI) of 1mm at the most anterior or posterior aspects of the joints. This was true for both sagittal and coronal measurements. The mean AA joint space was 0.6mm, with an upper 95% CI of 1.2mm at the lateral aspect of the joint on the coronal image only. The midsagittal structures demonstrated significantly higher standard deviation and variability. CONCLUSIONS: These results revealed consistently narrow joint spaces and left-right symmetry in the upper cervical spine joints that do not vary according to demographics. There was distinctly greater consistency in the coronal plane, which enabled more precise diagnostic measurement and side-to-side comparison of measurements. This precision will enable more accurate identification of abnormal scans, which should prompt consideration for additional workup. Thus, better understanding of these relationships may enable earlier detection of subtle craniocervical dissociative injuries based on CT scan data. This is important, because the only evidence of a severe injury on CT can be subtle misalignment.

Reference data for assessing widening between spinous processes in the cervical spine and the responsiveness of these measures to detecting abnormalities.

BACKGROUND CONTEXT: Traumatic injury to the spine is evaluated and treated based on the perceived stability of the spine. Recent classification schemes have established the importance of evaluating the discoligamentous complex to fully comprehend stability. There are a variety of techniques to evaluate the discoligamentous complex, including assessment of interspinous distance. However, there currently are no clinically validated methods to define and assess abnormal interspinous widening. PURPOSE: The purpose of the study was to provide reference data and evidence to support the objective use of spinous process widening in the diagnosis of cervical spine injury and instability. STUDY DESIGN: The study was designed to be biomechanical and observational. METHODS: Distances between spinous processes were measured from lateral flexion-extension X-rays of 156 skeletally mature asymptomatic subjects who reported never having had neck symptoms as well as 12 whole human cadavers before and after creating increasingly severe damage to posterior structures. Cervical interspinous distances were measured and then normalized to the width of the C4 vertebral end plate. The change in the distance from flexion to extension was also calculated. RESULTS: Descriptive statistics, including the 95% confidence intervals for each cervical level were tabulated for 863 levels in 149 analyzable asymptomatic volunteers. In the simulated cadaver model, interspinous widening was highly specific and mildly sensitive for detecting damage to the posterior structures of the cervical spine. CONCLUSIONS: This study provides reference data that can be used to quantitatively assess interspinous process widening in the cervical spine. Application of the reference data to a cadaver model of cervical trauma suggests that although objective evidence of abnormal widening may be uncommon, when present, it is suggestive of extensive damage to the cervical spine. Derived from this data were two "rule of thumb" criteria to identify abnormal interspinous widening in flexion X-rays; when greater than 30% relative to an adjacent level (40% between C1-C2 and C2-C3) or greater than 50% of the anterior-posterior width of the C4 vertebral body (30% for C2-C3).