J Neurosurg74:665-667, 1991

Vertical odontoid fracture Case report A. TOMMY BERGENHEIM, M.D., AND ~kKE FORSSELL, M.D. Departments of Neurosurgery and Neuroradiology, University Hospital, Ume~, Sweden

v" A case of vertical odontoid fracture is presented in which a concomitant fracture of the skull indicated possible pathogenetic mechanisms. The radiological diagnosis and the management of this case are discussed. KEy WORDS 9 odontoid fracture 9 spinal injury

HE classification by Anderson and D'Alonzo 2 identifies three main types of fracture of the odontoid. A case of vertical odontoid fracture not fitting into the classification and with unknown pathogenesis has recently been reported by Johnson, et al. ~t The present case is the second example of this rare entity to be reported in the literature.

T

computerized tomography

Discussion In the case of vertical odontoid fracture, previously reported by Johnson, et al., j~ the patient had been involved in a high-speed motor-vehicle accident. On admission she was awake, complaining of neck pain.

Case Report This 18-year-old man sustained a head injury in a motor-vehicle accident. On admission he was unconscious with wide nonreactive pupils bilaterally, but had no other neurological deficits. Computerized tomography (CT) of the skull showed bilateral fractures along the coronal suture and bifrontal epidural hematomas. After emergency trephination he remained unconscious with a flexion-pattern response to painful stimulation. On the 2nd day after the accident he developed paraparesis, and plain films of the cervical spine showed a fracture of the posterior arch of the atlas without displacement (Fig. 1). A C T scan of the cervical spine displayed a vertical fracture in a frontal plane through the odontoid peg, not visible on plain films (Fig. 2). The patient was initially treated with a halo brace, but later it was concluded that the fracture should be regarded as stable. Consequently, the halo brace was exchanged for a plastic collar which was kep~ in place for 8 weeks. The fracture healed without displacement. Six months after the injury the patient was walking, but a mild paresis of the left leg still persisted. He also had symptoms of brain damage with memory dysfunction and personality change. J. Neurosurg / Volume 74/April, I991

FIG. 1. Lateral plain x-ray film showing fracture of the lamina of C-I. Note the close proximity of the anterior edge of the foramen magnum and the odontoid process. 665

A. T. Bergenheim and ~.. Forssell

FIG. 2. Axial computerized tomography scans showing the vertically oriented odontoid fracture.

Neurological examination revealed no deficits. Since she was unable to recall the accident in detail there was no clue as to the pathogenetic mechanism of the fracture. In our case, the patient had total amnesia in relation to the accident. Obviously the car had gone off the road, and one may assume that the skull fracture was caused by his head hitting the windshield, as indicated by a bruise on his forehead. The probable direction of the force against the head is illustrated by the arrow in Fig. 3. There seem to be several mechanisms that might have caused the odontoid fracture in the present case although, as is stated in many studies on the pathogenesis of odontoid fractures) '~3 the mechanisms in these fractures are very complex and conclusions must be drawn with utmost care. If the injury is regarded as an avulsion fracture due to sudden stretch of the apical dental ligament and the alar ligaments of the axis, there are at least two possible explanations: either there was movement of the head after frontal impact, downward and backward on the superior articulations of the atlas, which would cause relaxation of the apical ligament and stretching of the two alar ligaments, or (as proposed by Johnson and coworkers j') before the impact hyperflexion occurred with stretching of both the apical and the alar ligaments. These two mechanisms, however, probably require a tear of the cruciform ligament. This would cause instability, which was not present in our case. In a series of cadaver studies it was shown that a Type 1 avulsion fracture 2 was most likely likely to result when the head was rotated and flexed, causing maximal extension of the alar ligaments7 ~ In our case, the location of the skull fracture indicated a more vertically directed trauma, which may have pushed the head downward and backward causing an extension movement of the head. This mechanism would allow the anterior edge of the foramen magnum to hit the odontoid peg in the axial direction and possibly cause a 666

vertical chisel-type fracture. Figure 1 shows the close proximity of the skeletal structures involved. This mechanism may also account for the C- 1 laminar fracture since this type of fracture usually occurs in extension injuries, often in association with odontoid fractures.~2 On the other hand, trauma in the longitudinal plane of the body with compression of the atlas often results in a Jefferson fracture.~6 In the present case the fracture of the atlas ring might have been caused by a similar mechanism. An isolated vertical fracture through the odontoid peg should be stable as long as there is no associated rupture of the cruciform ligament, and conservative management with a rigid plastic collar for at least 8 to 12 weeks should be appropriate therapy, m'~2This is in

FIG. 3. Lateral computerized tomography-topogram showing the probable direction of the force against the head (arrow). The bilateral fracture along the coronal suture is visible. J. Neurosurg. / Volume 74~April, 1991

Vertical odontoid fracture contrast to the Type 1 fracture which Scott, et al., ~4 indicated could cause atlanto-occipital instability and should be treated accordingly. In the present case there was no suspicion of fracture of the spine until the paraparesis developed. According to Clarke and White, 5 patients with odontoid fractures often present without neurological deficits or with nonspecific symptoms. Anderson and D'Alonzo 2 found neurological involvement in only 25% of their 60 cases with odontoid fracture, and the majority of these had only minor findings. Hadley and coworkers ~ reported on 40 cases with Type 2 fracture; in 39 of them there were no physical findings that could be related to the fracture, most of the patients only complaining of pain. Dunn and Seljeskog6 found only 20 patients with neurological deficits among 72 patients with C1-2 subluxation after odontoid fracture. This explains why fractures of the cervical spine are overlooked, particularly in patients with severe head injury. 4"15 According to Clarke and White, every patient involved in a motorvehicle accident should be evaluated for the possibility of having a fracture of the cervical spine. Usually, plain x-ray films are sufficient but, as in the present case, many odontoid fractures may be missed. 9 Topography or CT may add further to the diagnosis, 3"~-''~5but Type 2 fractures are not always visualized with CT. 3 References

1. Althoff B: Fracture of the odontoid process; an experimental and clinical study. Acta Orthop Scand Suppl 177: 1-95, 1979 2. Anderson LD, D'Alonzo RT: Fractures of the odontoid process of the axis. J Bone Joint Surg (Am) 56: 1663-1674, 1974 3. Baumgarten M, Mouradian W, Boger D, et al: Computed axial tomography in C1-C2 trauma. Spine 10:187-192, 1985

J. Neurosurg. / Volume 74/April, 1991

4. Bohlman HH: Acute fractures and dislocations of the cervical spine: an analysis of three hundred hospitalized patients and review of the literature. J Bone Joint Surg (Am) 61:1119-1142, 1979 5. Clarke CR, White AA IIl: Fractures of the dens. d Bone Joint Surg (Am) 67:1340-1348, 1985 6. Dunn ME, Seljeskog EL: Experience in the management of the odontoid process injuries: an analysis of 123 cases. Nenrosurgery 18:306-310, 1986 7. Dvorak J, Panjabi MM: Functional anatomy of the alar ligaments. Spine 12:183-190, 1987 8. Dvorak J, Schneider E, Saldinger P, et al: Biomechanics of the craniocervical region: the alar and transverse ligaments. J Orthop Res 6:452-46 l, 1988 9. Hadley MN, Browner C, Sonntag VKH: Axis fractures: a comprehensive review of management and treatment in 107 cases. Neurosurgery 17:281-290, 1985 10. Hadley MN, Dickrnan CA, Browner CM, et al: Acute traumatic atlas fractures: management and long term outcome. Neurosurgery 23:31-35, 1988 11. Johnson JE, Yang PJ, Seger JF, et al: Vertical fracture of the odontoid: CT diagnosis. J Comput Assist Tomogr 10: 311-312, 1986 12. Levine AM, Edwards CC: Treatment of injuries in the C1-C2 complex. Orthop Clin North Am 17:31--44, 1986 13. Mouradian WH, Fietti VG Jr, Cochran GBV, et al: Fractures of the odontoid: a laboratory and clinical study of mechanisms. Orthop Clin North Am 9:985-1001, 1978 14. Scott EW, Haid RW Jr, Peace D: Type I fractures of the odontoid process; implications for atlanto-occipital instability. Case report. J Neurosurg 72:488-492, 1990 15. Southwick WO: Management of fractures of the dens (odontoid process). J Bone Joint Surg (Am) 62:482-486, 1980 16. Zygmunt S, Ljunggren B: The Jefferson fracture. Travel Med Int 7:99-104, 1989 Manuscript received May 21, 1990. Accepted in final form September 24, 1990. Address reprint requests to: A. Tommy Bergenheim, M.D., Department of Neurosurgery, University Hospital, S-90I 85 UmeL Sweden.

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Vertical odontoid fracture. Case report.

A case of vertical odontoid fracture is presented in which a concomitant fracture of the skull indicated possible pathogenetic mechanisms. The radiolo...
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