Pain Doc: We've Got to Stop Paralyzing Patients

Scott Glaser, MD, president of Pain Specialists of Greater Chicago accidentally paralyzed a patient he was trying to help. The devastating mishap has stayed with him for years—and turned him into a crusader. He wants pain management physicians to stop using the standard spinal injection technique that he says caused the accident.

It is known as the “safe triangle” approach, a term Glaser finds bitterly ironic.

“I don’t want this to happen to any of you,” he told physicians attending the American Society of Interventional Pain Physicians (ASIPP) in Orlando, FL, the group’s annual meeting in April, 2015, referring to the accident. There are other safer ways to do such injections, Glaser said.

The approach is used in initiating a pain-blocking procedure called a transforaminal epidural steroid injection. But others see the potential hazards of using the “safe triangle” technique as “acceptable.”

“Nothing is risk free,” said Ramsin Benyamin, MD, past president of ASIPP, when asked about the controversy during an interview at the ASIPP meeting.

He does not dispute the fact that it has paralyzed patients. “The incidence [of paralysis] is just 17 or 18 cases in a procedure that’s been done for 25 years.”

Hans Hansen, MD, also a past president of ASIPP, agreed.

Glaser, an anesthesiologist with board certification in interventional pain management, said these accidents were likely avoidable, just as his mishap was.

In a first-person piece July 10, in MD Magazine, he recounted the events leading to his patient spending her last years as a paraplegic. The incident resulted in a malpractice case and settlement.

The patient, then an active, healthy woman in her early 70s had been in a boating accident that left her in pain that radiated down one leg. Confident he could block her pain, he began the procedure by inserting the needle into the “safe triangle” space. The adjective refers to the fact that the approach helps physicians avoid the nerve root. Unfortunately, that is not the only structure they need to avoid.

The needle pierced the patient’s radicular artery. The blood supply to the spinal cord was cut off. She was instantly paralyzed.

“Of course I blamed myself,” he said, “I went over and over it again, trying to see how I could have done this.” He kept coming back to the approach. Far from being safe, Glaser has since said repeatedly, this standard technique will always put that needle dangerously close to the artery. He wonders why more patients have not been injured—or if they have been but the accidents have gone unreported.

The tragedy, Glaser said, is that the danger can be avoided when physicians insert the needle below the nerve root and behind the disc.

One such approach was pioneered in the 1970s by Parviz Kambin, MD, a professor of orthopedics at Drexel University College of Medicine in Philadelphia, PA. It is called “Kambin’s triangle.”

At the Mayo Clinic in Rochester, MN, Naveen Murthy, MD, was asked whether he agreed that the “safe triangle” approach is risky. He said that approach is sometimes used in particular cases, but that in general, “We try to avoid the radiomedullary artery as much as possible to minimize potential injury in these elective procedures.“

Murthy continued, “By doing so, the vast majority of our cases are done using an infraneural approach within Kambin’s triangle.” [The full text of his comments is appended at the bottom of this article.]

Glaser has found several colleagues who agree the “safe triangle” should be abandoned.

They include Sairam Atluri, MD, medical director of the Tri-State Spine Care Institute in Cincinnati, OH; Gururau Sudarshan, MD, of Cincinnati Pain Management Consultants in Cincinnati; and Pavan Yerramsett, MD of Raleigh Neurology Associates, Raleigh, NC. also say that the “safe triangle” approach courts disaster. Writing in Pain Physician in 2011, they noted that while the procedure is usually done without complications “the artery can be compromised by direct trauma” since it is about the same size as the intruding needle, or by “spasm or by creation of an intimal flap obstructing blood flow.”

The “safe triangle” approach “requires placement of the needle precisely where the artery dwells,” Atluri and his colleagues wrote.

The 3 physicians called on specialty societies to take a stand and “encourage physicians to understand the nature of the problem and prevent future catastrophes.” Their research showed there had been at least 17 such accidents since 2002, and like Glaser they believe there were likely many more cases.

According to Glaser, nothing has changed. “If a procedure can be made safer and the risk possibly eliminated, it should be,” he said. “When I explain this to lawyers, they get it; lay people understand immediately,”

ADDITIONAL READING:

Below is the full response from Naveen S. Murthy, MD, associate professor at the Mayo Clinic in Rochester, MN and co-chair of the Spine Injection Practice in the radiology department’s division of musculoskeletal radiology. He was asked to comment on Glaser’s assertions.

It is true that the radiculomedullary artery is vulnerable to injury and inadvertent access using the “safe triangle” approach since we have shown that it resides in the upper third of the foramen in 88% of the cases that were reviewed¹. It should be noted that there have been no reported cases in the literature of a spinal cord injury with the use of non-particulate steroids. At the time of our original publication in 2010, it was generally felt that particulate steroids provided longer lasting benefit by a depot effect - the larger the particle, the greater the chance the steroid will remain in the site of interest and the longer for it to break down resulting in a greater duration of effect. Since that time, we have shown that a non-particulate steroid is not inferior to other particulate steroids in regards to pain or functional outcomes at two months for lumbar transforaminal epidural steroid injections². A randomized, blinded comparative effectiveness trial showed no difference between particulate and non-particulate steroids in pain relief, functional restoration, or surgical sparing at 6 months follow up³. Furthermore, in certain orthopaedic and neurosurgery procedures, it may be necessary to resect a radiculomedullary artery⁴. In these patients, there are commonly no spinal cord infarctions. This would lend credence to the theory that the spinal cord infarctions described in the literature related to transforaminal epidural steroid injections may be in fact due to the use of particulate steroids and embolization of the spinal cord rather than injury to the artery itself at the neural foramen. Particulate steroids can embolize the smaller end arteries that feed a larger region of the spinal cord which can lead to infarction.

In our practice, we exclusively use a non-particulate steroid for all transforaminal epidural injections. Additionally, we try to avoid the radiomedullary artery as much as possible to minimize potential injury in these elective procedures. By doing so, the vast majority of our cases are done using an infraneural approach within “Kambin’s triangle.” The “safe triangle” approach is reserved for cases where needle placement in this location provides the highest likelihood of corticosteroid delivery to the intended target. Typically, a supraneural approach using the “safe triangle” delivers corticosteroid to the root level of access and superiorly to potentially cover the root level above, while the infraneural approach using “Kambin’s triangle” also delivers corticosteroid to the root level of access and inferiorly to potentially cover the root level below. These differential flow patterns are considered when choosing an approach for a specific target.

References:

1. Murthy NS, Maus TP, Behrns CL. Intraforaminal location of the great anterior radiculomedullary artery (artery of Adamkiewicz): a retrospective review. Pain Med. 2010 Dec; 11(12):1756-64.

2. El-Yahchouchi C, Geske JR, Carter RE, Diehn FE, Wald JT, Murthy NS, Kaufmann TJ, Thielen KR, Morris JM, Amrami KK, Maus TP. The noninferiority of the nonparticulate steroid dexamethasone vs the particulate steroids betamethasone and triamcinolone in lumbar transforaminal epidural steroid injections. Pain Med 2013; 14(11): 1650-7.

3. Kennedy DJ, Plastaras C, Casey E, Visco CJ, Rittenberg JD, Conrad B, Sigler J, Dreyfuss P. Comparative effectiveness of lumbar transforaminal epidural steroid injections with particulate versus nonparticulate corticosteroids for lumbar radicular pain due to intervertebral disc herniation: a prospective, randomized, double-blind trial. Pain Med 2014; 15 (4): 548-55.

4. Murakami H, Kawahara N, Tomita K, Demura S, Kato S, Yoshioka K. Does interruption of the artery of Adamkiewicz during total en bloc spondylectomy affect neurologic function? Spine (Phila Pa 1976) 2010; 35 (22): E1187-92.

Below, asked to list the pros and cons of using the safe triangle approach, Murthy responded:

Pros:

• Avoids the radiculomedullary artery which is important when particulate steroids are being used.
• Lower risk for nerve stimulation/injury

Cons:

• Inadvertent puncture of the intervertebral disc which can cause transient pain and an increased risk of infection, albeit extremely small.
• Requires a patent lateral recess at the disc level for the steroid to reach the central epidural space.