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Slit fracture through two adjacent cervical vertebrae: case report and review of the literature.

Introduction

Owing to the complex embryology of the upper cervical spine, multiple congenital anomalies can be discovered at C1 and C2. (1) This becomes problematic when evaluating a cervical trauma patient for an often subtle fracture. (2-6) This is seldom the case, however, when evaluating the lower cervical spine. We present a rare case of a vertical or slit fracture of the body of C5 and C6 which on initial plain films could have been confused with a nutrient foramen and vessel pathway or a congenital midline defect.

Case Report

A fifteen year old boy presented to the emergency department complaining of numbness in his upper extremities after playing on a trampoline. His complaint began after doing a "double flip" and landing on his neck and head. He was unsure as to whether his neck was flexed or extended during the impact. He denied feeling instant pain or hearing any popping or cracking during the landing. He denied loss of consciousness, dizziness, nausea, or vomiting. The sensation of numbness resolved and he continued his normal activities.

On awakening the next morning the numbness returned and was accompanied by weakness of his left fourth finger. He described the it as "stiff." He had intense pain about the dorsum of the left hand and ventral aspect of the forearm extending to the palmar surface. He also perceived vague pain in the right upper extremity, neck, and low back. His left hand pain was provoked with tactile stimulation resulting in "hot and cold" sensations in the extremity. An attempt to relieve the pain with 800 mg Motrin was ineffective.

He had no relevant past medical or surgical history. He used no prescribed medications and had no known allergies. He reported a well rounded diet. His family history was significant for a father with an atrial fibrillation induced ischemic stroke at 41 years of age. He denied exposure to smoking and alcohol.

A review of systems revealed no evidence of systemic or neurological involvement, such as hoarseness, difficulty breathing, or bowel and bladder compromise. Physical exam revealed a well proportioned 60 kg child who appeared his stated age. He had a heart rate of 72 beats per minute, blood pressure of 134/86mm/Hg, and respirations at 18 per minute with O2 saturation of 100% on room air. He was awake, alert, in no distress, and cooperative throughout the exam.

His exam was unremarkable but for his neurological findings. The cranial nerves were intact. He had normal strength in his neck. He had normal upper extremity reflexes, 5/5 strength in the upper extremity except for apparent weakness of the left biceps and diminished grip strength in the left hand when compared to the right. Sensory involvement was localized to the left posterior lateral antebrachium and left and the right C6 dermatome as described above. He had intact lower extremity sensation, power, and reflexes. The Babinski sign was absent on the left and neutral on the right.

Routine laboratory findings were unremarkable. A CT scan showed a fracture of the left C5 pedicle and lamina as well as longitudinal fractures of the vertebral bodies of C5-C6 with no loss of height and no subluxation.

A neurosurgical consult was obtained. The diagnosis was an acute non-displaced slit fracture of the C5-6 cervical spine (Figure 1). He was stable and therefore placed in a soft collar. He was admitted to the PICU for observation with hourly neurological checks.

His hospital course was uneventful. On day one, he received an MRI (Figure 2) which showed mild bone marrow edema at C4 and edema corresponding to the fractures found on the CT scan. An intraspinous ligament sprain from C3-C4 to C6-C7 and a posterior longitudinal ligament sprain at C5-C6 were identified. Finally, a cord contusion was noted at the C5 level. He was transferred to the pediatric ward and a pediatric orthopedist was consulted.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

By day two his right sided upper extremity dysesthesia had resolved and the left side hyperesthesia had diminished. His pain was well controlled with medication. He was placed in a hard collar. A cross table c-spine film was obtained to access proper alignment with the brace. On day three, he was discharged in good condition, with minimal left sided C6 hypoesthesia and dysesthesia.

[FIGURE 3 OMITTED]

He returned to the emergency department a month later complaining of a cough and neck pain. A four view cervical spine study revealed no significant change in alignment, nor did it reveal any foraminal encroachment. In clinic shortly thereafter, he denied significant radiculopathy including hyperesthesia, despite maintaining an active lifestyle. He had been noncompliant with his cervical collar but denied any new trauma. A three month follow-up revealed healing of the cervical fractures (Figure 3).

Discussion

He was diagnosed as having a fracture of C5-6 but the pattern was quite unusual since this was a slit fracture over the body of C5 running about half of the body and then starting again at C6 with the same pattern (Figure 1). Of note, the C5-C6 disc appeared undamaged. We obtained an MRI to clarify the situation and indeed these lines were fracture lines with edema around them. There are no vascular markings (Figure 2).

Slit fractures are usually referenced in the literature only in regards to upper cervical trauma. The literature provides multiple references of the uncommon, but expected, midline clefts and congenital variants of the upper cervical spine. Slit fractures as reported in this case could not be found after extensive review of the literature.

This case serves as a reminder of the dangers associated with trampolines. A review of the recent literature reveals that 1.5% of all summer time emergency department visits at one children's hospital and 2.5% of all ER visits to another were for orthopedic injuries that occurred while playing on a trampoline. (7,8) In the United States an estimate of 88,563 trampoline induced ER visits occurred in a five year period ending in 2005. Of concern is the fact that this represented a 113% increase over a similar time span on decade ago. (9) The most common injury is of the foot and ankle, but neck sprains are second. (8,10) Trampoline injuries are the fourth leading cause of sports related CNS injuries, behind football, boxing, and hockey. (11)

In this case, the mechanism for the trauma to the bone may have been a result of the trampoline's ability to slow axial loading while the child was undergoing concurrent forced flexion. It has been shown that for the same energy and direction of impact, a high impact loading rate on calf lumbar spines produced fractures with significant posterior displacement, whereas minimal displacement was elicited for fractures produced at a low loading rates. (12) It has also been found that, although endplate and vertebra body failures were increased with loading rate, the stresses only increased with regard to the vertebral body. (13) Therefore, in slow loading the fracture pattern observed may be strictly related to the mechanical properties of the vertebral component in question, as opposed to high speed loading which may result in fracture patterns more consistent with load distribution.

It is likely the child was in forced flexion at the time of impact. A study has revealed that fractures were likely to occur in adolescent porcine motion segments when forced to a median angle of 17 degrees of flexion or extension. (14) Usually, the fractures in flexion-compression occurred posteriorly, as in the case above. In the study, the extension fractures tended to be more extensive and had a lower ultimate compressive load.

The child's age may have contributed to his unusual fracture pattern. A previous study, citing findings that adult vertebrae when compressed fracture through the body and adolescents through the growth plates, tested loading on adolescent porcine motion units. The results demonstrated the weakest point in an adolescent porcine unit is the growth plate and that the force usually resulted in nucleus pulposus herniation and displacement of the annulus through the fracture line. (15) The damage to the nucleus was readily found on MRI. These findings are contrary to the findings in our case, but to serve to suggest a difference between aged and adolescent spines.

The fact that the C5 disc did not rupture was of interest. It is believed that the ability of the nucleus to reach constant pressure regardless of impact duration resulted in the transmission of force to the cancellous bone. (16) In the above case, the cancellous bone responded to the slow dynamic load by a minimal fracture. However, the posterior elements were predictably overloaded, especially when anterior shear was considered. A study of porcine models demonstrated that anterior shear, i.e. flexion, allowed for an increase in ultimate load failure when the motion unit was dynamically loaded. (17) The study also reported the disc resisted up to 70% of the load with the pars responsible for 30%. In this study, as in our case, the posterior elements still incurred the majority of the mechanical failure.

References

(1.) Bonneville F, Jacamon M, Runge M, Jacquet G, Bonneville JF. Split atlas in a patient with odontoid fracture. Neuroradiology. 2004 Jun; 46(6):450-2. Epub 2004 Apr 23.

(2.) Georgopoulos CE, Jones DG, Davies DM. Injury to the upper cervical spine: fracture versus congenital anomaly. Am J Emerg Med. 1986 May; 4(3):235-7

(3.) Geusens E, Van Breuseghem I, Pans S, Brys R Some tips and tricks in reading cervical spine radiographs in trauma patients. JBR-BTR. 2005 Mar-Apr; 88(2):87-92.

(4.) Lander P, Gardner D, Hadjipavlou A. Pseudonotch of the atlas vertebra simulating fracture with computed tomographic diagnosis. A case report. Orthop Rev. 1991 Jul; 20(7):614-6.

(5.) O'Sullivan AW, McManus F. Occult congenital anomaly of the atlas presenting in the setting of acute trauma. Emerg Med J. 2004 Sep; 21(5):639-40

(6.) Prempe RC, Gibson JC, Bhattacharya JJ. Mid-line clefts of the atlas: a diagnostic dilemma. Spinal Cord. 2002 Feb; 40(2):92-3.

(7.) Hurson C, Browne K, Callender O, O'Donnell T, O'Neill A, Moore DP, Fogarty EE, Dowling FE. Pediatric trampoline injuries. J Pediatr Orthop. 2007 Oct-Nov; 27(7):729-32.

(8.) Shankar A, Williams K, Ryan M. Trampoline-related injury in children. Pediatr Emerg Care. 2006 Sep; 22(9):644-6.

(9.) Linakis JG, Mello MJ, Machan J, Amanullah S, Palmisciano LM. Emergency department visits for pediatric trampoline-related injuries: an update. : Acad Emerg Med. 2007 Jun; 14(6):539-44. Epub 2007 Apr 20.

(10.) Nysted M, Drogset JO. Trampoline injuries. Br J Sports Med. 2006 Dec; 40(12):984-7. Epub 2006 Sep 25.

(11.) Toth C, McNeil S, Feasby T Central nervous system injuries in sport and recreation: a systematic review. Sports Med. 2005; 35(8):685-715.

(12.) Tran NT, Watson NA, Tencer AF, Ching RP, Anderson PA. Mechanism of the burst fracture in the thoracolumbar spine. The effect of loading rate. Spine. 1995 Sep 15;20(18):1984-8.

(13.) Ochia RS, Tencer AF, Ching RP. Effect of loading rate on endplate and vertebral body strength in human lumbar vertebrae. J Biomech. 2003 Dec; 36(12):1875-81.

(14.) Baranto A, Ekstrom L, Hellstrom M, Lundin O, Holm S, Sward L. Fracture patterns of the adolescent porcine spine: an experimental loading study in bending-compression. Spine. 2005 Jan 1; 30(1):7582.

(15.) Lundin O, Ekstrom L, Hellstrom M, Holm S, Sward L. Injuries in the adolescent porcine spine exposed to mechanical compression. : Spine. 1998 Dec 1; 23(23):2574-9.

(16.) Lee CK, Kim YE, Lee CS, Hong YM, Jung JM, Goel VK. Impact response of the intervertebral disc in a finite-element model. Spine. 2000 Oct 1; 25(19):2431-9.

(17.) Yingling VR, McGill SM. Anterior shear of spinal motion segments. Kinematics, kinetics, and resultant injuries observed in a porcine model. Spine. 1999 Sep 15; 24(18):1882-9.

Tracy L. Hendershot, DC, MSIV

Department of Family and Community Health, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV

Toussaint A. Leclercq, MD

Department of Neurosciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV

Peter Chirico, MD

Radiology Department Chair, Cabell Huntington Hospital, Huntington, WV
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Title Annotation:Scientific Article
Author:Hendershot, Tracy L.; Leclercq, Toussaint A.; Chirico, Peter
Publication:West Virginia Medical Journal
Article Type:Clinical report
Date:Jan 1, 2010
Words:2020
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