Selective Vulnerability of the Foramen Magnum in a Rat Blast Traumatic Brain Injury Model.

Primary blast traumatic brain injury (bTBI) accounts for a significant proportion of wartime trauma. Previous studies have demonstrated direct brain injury by blast waves, but the effect of the location of the blast epicenter on the skull with regard to brain injury remains poorly characterized. In order to investigate the role of the blast epicenter location, we modified a previously established rodent model of cranium-only bTBI to evaluate two specific blast foci: a rostrally focused blast centered on bregma (B-bTBI), which excluded the foramen magnum region, and a caudally focused blast centered on the occipital crest, which included the foramen magnum region (FM-bTBI). At all blast overpressures studied (668-1880 kPa), rats subjected to FM-bTBI demonstrated strikingly higher mortality, increased durations of both apnea and hypoxia, and increased severity of convexity subdural hematomas, than rats subjected to B-bTBI. Together, these data suggest a unique role for the foramen magnum region in mortality and brain injury following blast exposure, and emphasize the importance of the choice of blast focus location in experimental models of bTBI.

Clival Screw Placement in Patient with atlas assimilation: A CT-based feasibility study.

Clival screw and plate fixation technique is an alternative or supplement to the occipitocervical instrumentation. However, no report has clarified the applied anatomy of clivus in patients with atlas assimilation (C1A), especially for clival screw fixation. Therefore, we measured the parameters of clival lengths, widths, putative screw lengths, clival-cervical angel and foramen magnum diameters on CT images in a cohort of 81 C1A patients and patients without C1A. The clivus showed a rectangular shape in 96.3% (78/81) of C1A patients, and a normal-like triangle shape in 3.7% (3/81) of C1A patients. The intracranial clival length decreased 13% (37 mm) in C1A patients, the extracranial clival length 14.8% (24.1 mm), the clival-cervical angle 6.2% (122.3°) and the superior screw length 11.3% (14.1 mm), the sagittal diameter of foramen magnum 16% (28.0 mm), respectively. There was no significant difference in the widest or narrowest clival width, or the middle screw length, or the transverse diameter of foramen magnum between groups. The inferior clivus was feasible for an average 9.7-mm-length screw placement in C1A patients, while not in patients without C1A. The present study characterizes clivus of C1A patients with an unnormal-like rectangular shape, and confirmes a screw placement at the inferior clivus.

Surviving Penetrating Brainstem Injury by Bamboo Sticks: Rare Case Reports and a Brief Review of Literature.

BACKGROUND AND IMPORTANCE: Chopsticks are common utensils used in many Asian cultures. However, they sometimes can be used as weapons or can cause accidents, particularly in children. Penetrating transorbital/transpharyngeal intracranial injuries with bamboo sticks are peculiar accidents and are relatively rare. Because of their rarity, the management of such injuries is often complex. We discuss 3 cases of penetration of the brainstem by bamboo sticks, 1 case through the foramen magnum, which, to the best of our knowledge, is the first reported case of such an injury. CLINICAL PRESENTATION: The case of a 50-year-old man who was stabbed with a pair of chopsticks in his left eye is presented. The chopsticks passed through the cavernous sinus, and the patient sustained superior orbital fissure syndrome. The other 2 cases were those of a 4-year-old girl having a similar pattern but different mechanism of injury and a 2-year-old boy who sustained transpharyngeal intracranial injury via the foramen magnum. Computed tomography, magnetic resonance imaging, and computed tomographic angiography (CTA) are the key imaging modalities frequently used to determine the course and extent of brain injury. CONCLUSION: Early surgical exploration by a multidisciplinary team approach is essential for attaining a favorable outcome. All cases demonstrated good postoperative recovery and were successfully managed by removing the foreign body through its trajectory. We discuss and briefly review the literature on patterns, complications, and management issues of these less common injuries.

Does the morphology of foramen transversarium fractures predict vertebral artery injuries?

STUDY DESIGN: Retrospective review of foramen transversarium fracture morphology variables and their relationship to vertebral artery injury. OBJECTIVE: We examined the morphology of foramen transversarium fractures to determine if different patterns of these fractures predicted vertebral artery injury to more specifically identify at risk patterns in which vertebral artery evaluation may be warranted. SUMMARY OF BACKGROUND DATA: Risk fractures for vertebral artery injury have been previously reported to include cervical subluxation or dislocations, C1-C3 fractures, and foramen transversarium fractures. There have been no reports determining if specific foramen transversarium fracture patterns are predictive of vertebral artery injuries. METHODS: We reviewed the initial cervical CT scans of 171 patients seen in our level one trauma center between January 2002 and March 2008 and identified all patients with foramen transversarium fractures. Additionally, CT angiograms were reviewed in these patients to identify patients with vertebral artery injuries. The morphology of the foramen transversarium fractures was compared in those patients with and without vertebral artery injury to identify fracture patterns predictive of arterial injury. RESULTS: Twenty-one (12%) patients were found to have foramen transversarium fractures with 5 (24%) of these patients having associated vertebral artery injury. Multilevel foramen transversarium fractures (P = 0.025) were significantly more frequent in vertebral artery injuries. Logistic regression identified multilevel fractures (odds ratio 17.33) and fracture comminution (odds ratio 10.50) as significant variables influencing vertebral artery injury after foramen transversarium fracture. CONCLUSION: We found patients presenting with multilevel foramen transversarium fractures and foramen transversarium fracture comminution to be at significantly increased odds of vertebral artery injury. Patients with these fracture patterns should undergo further evaluation with vertebral artery imaging.

Unusual transoral penetrating injury of the foramen magnum: case report.

OBJECTIVE AND IMPORTANCE: Penetrating injuries of the cranium and spine are frequent to the civilian neurosurgical practice. Although a variety of unusual objects have been reported, to our knowledge, there has never been a craniocerebral or spinal injury caused by a fish. An unusual case of transoral penetration of the foramen magnum by a billed fish is described. The history, radiographic studies, and treatment are presented. CLINICAL PRESENTATION: A fisherman struck by a jumping fish initially presented with severe neck pain and stiffness, bleeding from the mouth, and a laceration in the right posterior pharynx. A computed tomographic scan of the cervical spine revealed a wedge-shaped, hyperdense object extending from the posterior pharynx into the spinal canal between the atlas and the occiput. Because of the time factor involved, the fisherman was brought directly to surgery for transoral removal of the object. INTERVENTION: The patient was placed under general anesthesia, and with a tonsillar retractor, a kipner, and hand-held retractors, the object was visualized and identified as a fish bill. Further dissection above the anterior aspect of the atlas permitted removal of the object by means of a grabber from an arthroscopic set. No expression of cerebrospinal fluid was noted, and a Penrose drain was placed. CONCLUSION: The patient was treated under the assumption that penetrating foreign objects in continuity with the cerebrospinal fluid space and the outside environment should be removed as soon as possible. The patient was provided appropriate antibiotics to treat potential infection of normal pharyngeal flora and organisms unique to the marine environment. The patient recovered and did not experience any residual neurological deficit.

Injury caused by deeply penetrating knife blade lodged in infratemporal fossa.

Knife-inflicted, deeply penetrating head and neck trauma is an uncommon life-threatening injury and a challenging problem. An examination of the neurovascular and systemic physical status is a first requirement and the decision as to which approach to adopt for the removal of the blade is of critical importance. Here we report a rare case of a pre-auricular stab wound with the knife blade deeply lodged in the extracranial infratemporal fossa. Radiological investigations showed that the knife blade had entered from the temporomandibular joint and become lodged through the anterior margin of foremen magnum below the petrosal bone. Minimal left vocal cord paresis, left palatal weakness and a slight deviation of the tongue towards the left side were observed. The other neurological and systemic physical evaluations were normal. Simple withdrawal of the blade in the operating room did not cause serious neurovascular injury. Here we discuss and compare the expanded exposure of anatomical structures for blade removal and simple withdrawal in similar injuries.

The risk of foraminal violation and nerve root impingement after anterior placement of lumbar interbody fusion cages.

STUDY DESIGN: Three groups of six embalmed cadaver spines underwent placement of lumbar interbody fusion cages centered either at midline, 10% lateral of midline, or 20% lateral of midline. The spines were evaluated for evidence of neuroforamen violation or nerve root impingement. OBJECTIVES: To determine the potential for foraminal violation or nerve root impingement after correct placement and lateral misplacement of lumbar interbody fusion cages. SUMMARY OF BACKGROUND DATA: Radicular symptoms after anterior cage placement have raised some concern about the potential for inadvertent device-related foraminal violation not adequately appreciated by intraoperative fluoroscopy. METHODS: Preoperative computed tomography scanning and plain radiography was used to measure endplate dimensions at L4-L5 and to template the appropriately sized interbody fusion cages. The cadaveric specimens were randomly divided into three groups of six (Groups I-III) and instrumented at L4-L5 either at midline (I) or 10% (II) or 20% (III) lateral of midline. Postoperative computed tomography and plain radiography was evaluated for evidence of neuroforamen violation, followed by dissection of the specimens. RESULTS: Foraminal violation occurred in one of six spines in group II (10% off midline) and in three of six spines in group III (20% off midline). Two of the three cadavers in group III with foraminal violation also were noted to have nerve root abutment on computed tomography scans and spinal dissection. CONCLUSIONS: Excessive lateral placement of lumbar interbody fusion cages may result in foraminal violation and possible nerve encroachment. The "safe zone" for centering the cages extends approximately 5 mm on either side of midline.

Avulsion fracture of the anterior half of the foramen magnum involving the bilateral occipital condyles and the inferior clivus--case report.

A 38-year-old male presented with an avulsion fracture of the anterior half of the foramen magnum due to a traffic accident. He had palsy of the bilateral VI, left IX, and left X cranial nerves, weakness of his left upper extremity, and crossed sensory loss. He was treated conservatively and placed in a halo brace for 16 weeks. After immobilization, swallowing, hoarseness, and left upper extremity weakness improved. Hyperextension with a rotatory component probably resulted in strain in the tectorial membrane and alar ligaments, resulting in avulsion fracture at the sites of attachment, the bilateral occipital condyles and the inferior portion of the clivus. Conservative treatment is probably optimum even for this unusual and severe type of occipital condyle fracture.

Diagnosis and management of occipital condyle fractures.

The authors recently treated three cases involving fractures of the occipital condyle. First described by Bell in 1817, this lesion has proven to be very rare, with only 32 cases previously reported in the literature. Plain films often do not reveal any abnormality, making diagnosis difficult. High-resolution computed tomography has been demonstrated to be very sensitive in diagnosing this lesion. This fact was borne out in the authors' series. All of the authors' patients were managed either with a Philadelphia collar or with halo fixation, with excellent outcomes.

Neuroimaging of fractureless transforamen magnum penetrating injury of the cerebellum.

An unusual case of penetrating injury to the cerebellum by a foreign body is described. The authors recommend plain radiographs and computed tomography to rule out fractures of the skull vault and base and the upper cervical spine, as well as to ascertain the presence and location of foreign bodies. Magnetic resonance imaging is ideal for the follow-up assessment of brain damage.

An unusual cranial injury caused by an industrial nail-gun.

An unusual case of an industrial nail-gun injury is presented. A 36-year-old man was struck in the back of his neck by a nail, which was fired from a high velocity Ramset nail-gun. The nail passed through the foramen magnum to lodge in front of the brainstem. In spite of the close proximity of the nail's trajectory to the upper cervical spinal cord and the brain stem, no major neurological damage resulted. The nail was removed successfully the following day. This case illustrates the potential for serious injury from nail-guns.