Another BMA Video: Reduction of Cervical Dislocations

Non-operative reduction of a cervical dislocation can be extremely difficult.  Even with modern techniques and technology, it is occasionally not possible to reduce a cervical subluxation non-operatively.  However, with modern anesthesia, muscle relaxants, and traction systems, it has to be much easier than what it was in 1936.

Here’s another video produced by the British Medical Association; this time demonstrating an attempted cervical reduction of bilateral jumped facets at C5-6.  The x-ray is striking.  Cases of such severe subluxation without spinal cord injury are rare.  The attempted reduction is brutal and ineffective.  Modern reduction techniques are much more controlled and safe.

Also shown is a case of unilateral subluxation in an infant after a tonsilectomy.  Although there are no x-rays, no images of the reduction procedure, and no follow-up, the pre-reduction examination is striking and informative.

Errata

1.  I met Chris Shaffrey from the UVA Department of Neurosurgery.  He’s a specialist in spinal disorders with an emphasis on spinal deformity.  I came away very impressed, particularly with his evidence-based approach to spine surgery.

2.  X-rays can miss many fractures.  It has long been debated about the relative cost-benefit ratio of x-rays versus computed tomography (CT) for spinal fractures after trauma.  X-rays are much cheaper.  CT scans are much more thorough and sensitive.  This paper suggests that more fractures may be missed by traditional x-rays than had previously been thought.  Perhaps a CT scan is worth the additional cost.

3.  Vycor medical products has developed a novel brain retractor called the Viewsite.  Traditionally, malleable blade retractors have been used to retract the brain during a neurosurgical procedure.  These retractors have many limitations:  they concentrate the retractive force on a small segment of brain; they have sharp edges that can cut into the brain; they are opaque blocking visualization of tissues behind the retractor.  The Viewsite uses a novel circumferential retraction system to distribute the retractive force on a wider surface.  Here’s how the company describes it:

The ViewSite™ Brain Access System is a revolutionary approach in brain retraction. Each ViewSite system consists of an introducer and a working channel port that allows the surgeon a seamless entry to the targeted site while distributing brain tissue evenly in a 360° dispersion pattern. Other ViewSite benefits include superior binocular vision to see in and around the surgical site; multiple sizes in different widths and lengths to meet all surgical needs and compatibility with most surgical arms to avoid accidental displacement or movement during surgery.

Spinal Surgery – First Principles

There are three common reasons to perform surgery on the spine:

1. Treat or prevent neurologic deficits.
2. Treat or prevent spinal deformity.
3. Pain.

The far most common reason for spinal surgery is the third: pain.  However, it probably also has the lowest probability of success.  About 20% of patients undergoing a spinal operation will require a repeat operation at some point.  This can be for a large variety of reasons, of course, many of which are unrelated to the reason the first surgery was performed.  It is an alarming statistic nonetheless.

Standard Measurements at the Craniocervical Junction

C.A. Rojas, J.C. Bertozzi, C.R. Martinez, and J. Whitlow published a paper in 2007 where they reevaluated traditional measurements at the occipitocervical junction using modern radiographic techniques.  Here is a table of their key findings.

Indices	Traditional Measurement	New Measurement
BAI	< 12	not reliable
BDI	< 12	< 8.5
Power’s Ratio	< 1.0	< 0.9
ADI	< 3 men < 2.5 women	< 2 both sexes
AOI	not reported	< 1.4

BAI:  Basion-Axial Interval

BDI:  Basion-Dens Interval

Power’s Ratio: BAI/AOI

ADI:  AtlantoDental Interval

AOI:  AtlantoOccipital Interval

Occipitocervical Dislocation

Occipitocervical dislocation (or occipitoatlantal dislocation) results from the disruption of the joint between the skull and the spine.  Usually, this only results from high energy injuries such as motor vehicle accidents.  It is more common in children, and children are more likely to survive such an injury.  It has an extremely high mortality – as much as 80% or more.

The skull articulates with the spine by both bony and ligamentous structures.  At the base of the skull are two regions of thickened bone known as the occipital condyles.  The condyles are seated on the lateral masses of the C1 vertebra forming the bony componentof the craniovertebral junction.  C1 is also known as the atlas.  The principal ligamentous contribution to the occipitocervical articulation is from the alar ligaments.  These originate from the basion and insert on the odontoid process of C2.

A high index of suspicion for occipitoatlantal dislocation should be maintained in all instances of high energy injuries.  Radiographic findings are not always obvious, and therefore special attention should always be payed to the OC junction.  Careful inspection of the anatomic relationships is mandatory.  Subluxation of the occipital condyles may be identified on sagittal CT reconstructions.  If the alignment is not correct or the joint space is increased, the joint should be presumed unstable.  Other indices that should be checked in suspicious cases are the BDI and the BAI.

If there is any malalignment, patients need to be managed with extreme caution.  OC disassociations can be extremely unstable.  The majority of patients with OC dislocations present with incomplete spinal cord injuries, although they may also have a normal neurologic examination.  Complete injuries are presumed to be universally fatal.

Children with minimal displacement may be considered for treatment in a halo-vest.  All other patients should be managed with occipitocervical fusion.