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Case Report: Cervical Fracture in an eight-week-old Cocker Spaniel.

An eight-week-old, female Cocker Spaniel was referred with tetraparesis.  The owner reported that the dog had collided with a stair-gate three days prior.  She had initially appeared unaffected, although veterinary assessment at the time had revealed cervical spinal pain.  48 hours later she developed generalised ataxia with increased guarding of the neck.  Progressive tetraparesis became evidence over the following 24 hours.

 

Assessment

On presentation, mentation was normal although she appeared anxious and reluctant to move, with guarding of the neck.  There was voluntary movement in all limbs, but the patient was unable to stand unaided.  Neurological assessment revealed increased segmental spinal reflexes with increased motor tone in all limbs, consistent with a cervical spinal lesion in the Ce1-5 cord segments.

Lateral view (above) reveals fracture of the cranial end-plate physis of Ce2 with concurrent disruption to the dorsal atlantoaxial ligament, resulting in significant stepping of the neural canal.The ventrodorsal view (right) reveals a normal dens and articulation of the synovial joint between Ce1 & Ce2.

The patient was anaesthetised for radiology, (see left, above right) taking care to support the cervical spine;  this revealed an unstable fracture of the body of Ce2 with associated stepping of the neural canal.

 

Treatment

The patient was prepared for aseptic surgery and transferred to theatre whilst carefully supporting the cervical spine.

A median, ventral surgical approach was employed to expose the ventral aspect of Ce1 and Ce2(1).  Fibrous callus around the fracture site was debrided to allow the caudal fragment of Ce2 to be gently elevated into anatomical reduction.  1.5mm screws were placed into the body of Ce2, the cranial end-plate of Ce2 and the ventral, muscular process of Ce1.  All screw-heads were then bridged with bone cement.  Closure was routine and the patient made an unremarkable recovery from anaesthesia.  A transdermal fentanyl patch 12ug/hr (Durogesic 12) was applied to aid postoperative analgesia.

Post-operative radiology (right) revealed anatomical reduction of the fracture with restoration of the normal alignment of the neural canal.

By the following day, the patient was much brighter and ambulatory, although she still occasionally stumbled on the thoracic limbs.  Cage rest was employed to minimise the risk of disruption to the repair.  Control radiology three weeks later revealed fracture healing.

 

Discussion

The initial presentation of neck pain with an absence of neurological deficits did not suggest significant trauma.  This contrasts with the majority of unstable spinal fractures which develop peracute deficits.  It is possible that the fracture was initially non-displaced, but subsequently shifted to its preoperative position sometime after the initial trauma as a result of normal daily activity.

Many spinal fractures can be successfully managed non-surgically.  The decision to operate depends on the biomechanics of the fracture configuration(2) but particularly those involving the ventral compartment and/ or marked subluxation of  intervertebral joints so as to disrupt the alignment of the neural canal.

Fracture management in immature patients generally involves minimal surgical intervention and early implant removal where possible, as healing is rapid and implants may affect subsequent development.  In this case, the fracture configuration indicated anatomical reduction with rigid internal fixation.  The risk of iatrogenic trauma negates early implant removal here, given expected exuberant callus formation and potential for damage to overlying soft-tissue structures.

Nevertheless, on-going monitoring for signs of implant-related problems would be advisable.

 

References

1. Sharp NJH, Wheeler SJ (2005) Atlantoaxial Subluxation in Small Animal Spinal Disorders p171-3 Elsevier Mosby

2. Sharp NJH, Wheeler SJ (2005) Trauma in Small Animal Spinal Disorders p286-9 Elsevier Mosby