In the conventional surgical procedure (spinal fusion) for spinal deformity, usually you do not open the vertebral canal and do not see the dural sac. So you have to count on the data obtained by the SSEP-monitoring.
Anyway, I do not see any clear relationship beteween spinal cord pulsations and intraoperative monitoring data.
Professor Tanchev, Many thanks for your reply,I will reform the question. In case of kyphosis treated by PSO, and I have no SSEP nor MEP and I noticed during the closure of the PSO disappearance of the cord pulsations during closure. Is there any published data about preserving the pulsations?
If you fear spinal cord damage, and you do not have SSEP then you should have to perform the "wake up " test. Did you try it your given case ?
We perform wake up routinely but in the last case I lost the cord pulsations after the correction and the test was negative. By exploring around the cord it was not compressed, We minimized correction to a great degree (almost no correction) but the patient was incomplete paraplegic
Dear Dr. Gad,
Obviously, loss of dural sac pulsations was an alarming sign. You have performed the wake up test and you have done correctly what should be done in such unhappy situation. One must hope that some recovery would happen postoperatively.
dear Dr. Gad,
All central cords in kyphotic patients are under pathological thightness or tension, as I found out myself in many PSO's. It is completely in accordance with the concepts and research Prof. Milan Roth did on the discongruency of growth. No a huge problem in sedentary lifestyle.
I had several time the experience, that procedures on serieus kyphosis had no usable SSEP before surgery in neuromuscular disabled chidren. But also that in the early start of the procedure teh monitoring stopped, in one clearly by overstrretching the neck in lordosis, while the cord was already under tension and riding over the kyphotic deformity.The SSEP's returned after repositioning the head!
But in all PSO'you see at closure that the pulsations in the liquor is coming back. I had two cases of disappeared Signals, but by closing the osteotomy pulsations where clear and the dura completely ballooned. The handling of the cord can be a source of temporary motoric paraplegia. Postoperative motor deficit disappeared in those cases completely.
So just wait and hope that only by some extra traction only the motorneurons ventral got some "neuropraxia".
We had a incidence during neuro muscular scoliosis surgery where throughout the surgery MEP were preserved but wake up test was negative. we relased the correction asap. Immediately after releasing correction some increase in MEP was noticed. Postoperatively patient had complete paraplegia but gradual recovery was observed upto 6 weeks
SSEP monitoring is very popular, but one should not forget that pseudodeviations are possible. So wake up test is still very useful and it is not consigned to history.
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