SpineUniverse Case Study Library

Basilar Invagination

History

The patient is a 67-year-old woman with rheumatoid arthritis who has chronically taken steroids for 25 years. Her chief complaints are facial numbness, and neck and occipital pain, which have all been present for the last 10 years. More recently, the patient has started to experience progressive arm and leg weakness with increased pain. Though she doesn't have any difficulty swallowing, she does experience difficulty breathing when she has a cold.

Prior Treatment

The patient's past medical history includes 26 prior extensive orthopaedic surgeries, including bilateral hip replacement, bilateral knee replacement, and right forefoot reconstruction complicated by extensive methicillin-resistant Staphylococcus aureus infection and subsequent right below-knee amputation.

Examination

The patient's motor exam shows her arms are weaker than her legs at 3 to 4/5 strength, as opposed to 4 to 5/5 leg strength. She has dysequilibrium with unsteady gait.

Pre-operative Images

Figure 1.jpgFigure 1: Lateral cervical spine x-ray shows erosion of dens with cranial settling.

Figure 2.jpgFigure 2: Sagittal T2-weighted MRI shows deformed dens with cephalad migration through the foramen magnum causing cervicomedullary compression.

Diagnosis

Basilar invagination.

Suggest Treatment

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Selected Treatment

The patient underwent pre-operative traction, posterior occipitocervical decompression, and instrumented arthrodesis.

Two days before surgery, craniocervical traction starting with 5 lbs was applied to the patient. The weight was increased in 5-lb increments and followed by neurologic examination. At 40 pounds, she had improved arm strength.

Immediately prior to surgery, the patient was placed in a halo vest with a line of sight satisfactory to the patient. She was positioned prone in a halo vest and after connecting to the Mayfield attachment, the posterior halo bars and vest were removed for surgery.

A suboccipital craniectomy with C1 to C3 laminectomy was performed for bony decompression, followed by instrumented arthrodesis from occiput to C6. After surgery, the halo vest was reapplied.

Pre-operative Traction

Figure 3.jpgFigure 3: Lateral cervical spine x-ray in traction shows slightly increased distance between the C1 and C2 posterior arch.

Post-operative Images

Figure 4.jpgFigure 4: Post-operative CT with sagittal reconstruction shows the extent of bony decompression. Note that a slightly decreased basilar invagination was achieved with pre-operative traction.

Figure 5.jpgFigure 5: One-year post-operative lateral cervical spine x-ray shows fusion from occiput to C6.

Figure 6.jpgFigure 6: One-year post-operative sagittal T2-weighted MRI shows no dramatic improvement in the cervicomedullary kink. However, indirect decompression and fusion were enough for near-complete resolution of pre-operative signs and symptoms.

Outcome

The immediate post-operative course was complicated by dysphagia, which required a NG tube. However, the patient was ambulating with a front wheel walker upon discharge.

One-month post-op follow-up showed that the patient was depressed due to the NG tube, but she reported resolution of facial numbness and improving arm and leg strength. The NG tube was removed one week later, and she started a diet of thick liquids per her speech pathologist's recommendation.

At the 3-month post-op follow-up, she reported mild surgical neck pain. Her arm strength exam was rated at 4/5 and leg strength at 5/5. The patient is much happier overall.

At her 6-month post-op follow-up, the patient's dysphagia was completely resolved. At the 1-year follow-up appointment, she reported a complete resolution of pre-operative symptoms with the return of normal strength, except for a slightly weak hand grip.

Case Discussion

Dr. Kim presents a case of basilar invagination in a rheumatoid patient with myelopathy that was successfully treated with decompression and fusion. He achieved excellent results with a well-accepted technique.

In addition to the options that he outlined, there are a few other options that have been reported:

  • Place spacers between the C1-C2 joint to reduce the invaginated dens, followed by a posterior C1-C2 or occipitocervical fusion.
  • Perform a similar procedure anteriorly.
  • Use an anterior plate that allows for reduction, as well as arthrodesis, with or without dens resection.
  • Perform an arthrodesis, either anteriorly or posteriorly, without any decompression.
  • Decompress anteriorly and instrument the occipitocervical junction with a Ransford loop with no fusion.

All of these techniques have been reported to yield successful results. To my knowledge, there is no study that has compared all of these various options to determine which results in the best outcomes.

In the absence of Class I data comparing the results, one is left with only case studies and therefore, suggestions on what the possibilities are. In that light, one might argue for choosing a procedure with the least morbidity, which varies according to the patient and the surgeon.

Although most surgeons prefer to use traction as Dr. Kim did, I rarely use pre-operative traction, which has several negatives. First, a hospital stay can expose the patient to hospital-acquired pathogens. Second, rheumatoids with fragile skin can develop decubitus ulcers. Third, pre-operative traction adds to the cost of surgery. Finally, what takes days to achieve with the patient awake can almost always be achieved in seconds to minutes with them under general anesthesia and muscle relaxants. What cannot be achieved with intra-operative traction can be achieved with distraction instrumentation.

As far as decompression, my preference is to reserve it for patients who do not improve with stabilization or who are quadriparetic. I share the experience that others have had in treating patients with profound myelopathy with instrumented arthrodesis without decompression. It is rare to see someone who requires subsequent decompression. If a patient is quadriparetic, I believe that one can, with adequate distal fixation, distract the occipitocervical junction adequately to indirectly decompress the cranio-cervical junction. Abumi used cervical pedicle screws to achieve this, but one can get equivalent results if enough distal fixation is used. Alternatively, one can perform the arthrodesis and, if the patient is still symptomatic, perform transoral decompression.

In summary, I congratulate Dr. Kim for an excellent result. What is desperately needed in our literature is a well-done study that can guide us on the necessity of pre-operative traction, decompression, and fusion in rheumatoid patients with basilar invagination.

Community Case Discussion (3 comments)

SpineUniverse invites spine professionals to share their thoughts on this case.


If we decided for a posterior decompression and arthrodesis or only posterior arthrodesis and after some months we decided for an anterior decompression (dens), my doubt is about the feasebility on the anterior procedure with the head already in a fixed position and a limited mouth opening?

I fully agree. my preference is for decompression as it allows more breathing space for spinal cord.

I congratulate Dr kim for the successful surgery. I agree with Dr Daniel that probably equivalent results would have been acheived with only traction and instrumentation without the need for decompression posteriorly--- problems 1. most of the pressure was from anterior which was decompressed with traction alone by indirect method. 2. you are reducing the surface area for application of bone graft posteriorly thereby relying mainly on your instrumentation.

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