Nancy A. Melville

May 13, 2016

CHICAGO — An innovative, minimally invasive endoscopic approach to lumbar fusion spinal surgery under conscious sedation shows success as a feasible alternative to traditional lumbar spine fusion, allowing for faster recovery without general anesthesia or intubation, a case series suggests.

"When used in select patients, this approach offers excellent improvement rates win pain and disability with a rapid recovery," said presenter Michael Y. Wang, MD, professor and spine director in the Department of Neurological Surgery & Rehab Medicine at the Miller School of Medicine at the University of Miami in Florida.

As opposed to conventional surgery, the method includes endoscopic, or "awake" lumbar fusion, combined with a recovery approach called enhanced recovery after surgery (ERAS), Dr Wang explained.

"[ERAS] is a patient-focused, team approach involving fast-tracking patients through their surgical process and recovery, and it is iterative, meaning it is a quality improvement process that changes just about everything about how the patient is managed through the whole surgical process."

"If you haven’t heard of this, I would highly recommend you look into how this is being used around the world in other surgical fields, such as bowel surgery," he told the audience during a plenary session here at the American Association of Neurological Surgeons (AANS) 84th Annual Meeting.

In developing an ERAS approach tailored specifically for spinal fusion, Dr Wang and his colleagues identified six key components: an endoscopic approach without general anaesthesia or intubation, use of percutaneous fixation, use of long-acting local analgesia, use of specialized expandable interbody cages, osteobiologics for fusion and promotion of osteogenesis, and "awake" anesthesia.

For now, Dr Wang dubbed the model "ERAS Spine Surgery, Version 1.0."

"These are the six components that we will likely see continue to improve over time,” he said.

In presenting a case series of 10 patients treated with the method, Dr Wang explained that all were treated with endoscopic access through Kambin's triangle, allowing for neural decompression, discectomy, endplate preparation, and interbody fusion.

With use of bupivacaine (Exparel, Pacira) for long-acting analgesia, percutaneous pedicle screws were used and a connecting rod was placed.

The patients, who had an average age of 62.2 years, all had severe disc height collapse, including 60% with grade I spondylolisthesis.

The mean operative time was 113.5 minutes, and mean blood loss was 65 mL (30 to 190 mL).

Patients had a mean length of hospital stay of 1.4 nights, which is significantly shorter than with conventional surgery.

"With open surgery, patients will stay an average of 4.2 days and even with MIS [minimally invasive surgery] it is 3.5 days, so this is a real change and departure," Dr Wang said.

With a minimum follow-up of 1 year follow-up, the patients had significant improvement in Oswestry Disability Index (ODI) measures, from a preoperative average of 42.0 to 13.3.

Scores on the 36-Item Short Form Health Survey improved from 47.6 to 49.7, while EuroQol five-dimensional scores improved from 10.7 to 14.2.

There were no cases of nonunion identified on follow-up imaging, no intraoperative or postoperative complications, no conversions to general anesthesia, and no conversions to open surgery in the case series.

In terms of narcotic use, Dr Wang reported morphine equivalent levels that were approximately two thirds of those typically used in standard MIS on postoperative day 1; they were approximately one third of MIS levels on postoperative day 2. No narcotic was used on the days after. In comparison, with MIS there was continued use of nearly 20 morphine equivalent units at least through postoperative day 7.

Dr Wang reported that since the case series was published in the Journal of Neurosurgery in February, the number of patients treated with the approach has grown to 50, and among them there was 1 patient who had to convert to general anesthesia after vomiting while in a prone position.

"We were able to protect her airway, and there was no aspiration," he said. "The patient was able to leave the next day without any other problems."

Other lessons learned in the 50 cases include the importance of endoscope cleaning and sterilization, the possibility of the need for two levels, and the fact that grade II spondylolisthesis can be treated.

"We've learned these things through the ERAS iterative process, which has shown to be critical for improvement," Dr Wang said.

Dr Wang described a typical patient 1 hour after surgery. "She is up and walking and talking to me — about 80% of patients are like this," he said.

He noted the contrast to the experience with conventional surgery. "Patients often fear what we as spine surgeons are going to do to them — the 'cost' of the surgery can involve the recovery process of actually experiencing more pain and discomfort, sometimes for 3 to 6 months."

"If we could change that curve, we can consider what it could mean for patients in terms of their recovery, functionality, and socioeconomic impact."

Dr Wang noted several important flaws and limitations of the case series and the approach itself, including the study's small sample size, the need for longer follow-up, the need for capital equipment investment, and the fact that some aspects are off-label.

"In addition, one of the biggest problems is limits in decompression and we're not able to fully do a laminectomy — that's something that needs to be developed technologically, and there is also difficulty in treating L5/S1," he said.

Intriguing Insights

In commenting on the study, Michael Glantz, MD, from the Pennsylvania State College of Medicine-Hershey Medical Center’s Department of Neurosurgery, said the study offers intriguing insights.

"The study [offers] class IV but dramatic evidence that is clinically relevant and statistically significant, showing sustained decline in what some would say is the most important measure of all in outcomes of spinal surgery — which is the ODI."

"This is hypothesis-generating, but I think it provides enough support to proceed to a good phase 2 trial," he added. "I think this is a really exciting [approach], and I look forward to the results."

Kevin T. Foley, MD, a discussant for the talk and professor of neurosurgery, orthopedic surgery, and biomedical engineering at the University of Tennessee Health Science Center in Memphis, said, however, that issues of airway management in prone, heavily sedated patients raise concern.

"I would say [the researchers] haven’t shown a statistical significance between factors such as length of stay that justifies heavily sedated patients placed in the prone position without airway protection," he said.

"Until we see some more information, I believe the risk likely outweighs the potential reward."

Dr Wang’s disclosures included relationships with Depuy Spine, Aesculap Spine, Spinicity, Neuro Consulting LLC, ISD, JoiMax, K2M, Quality Medical Publishing, and the Department of Defense. Dr Glantz has a consulting relationship with Abbvee Pharmaceuticals and has received an honorarium from SigmaTau Pharmaceuticals. Dr Foley is a consultant to and receives royalties from Medtronic; he is a board member and stockholder for BioD, Discgenics, and TruVision.

American Association of Neurological Surgeons (AANS) 84th Annual Meeting. Abstract 601. Presented May 2, 2016.

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