Dr. Zarina Ali, MD, assistant professor of neurosurgery and co-director of the Penn Nerve Center talks about how an outpatient surgery fixed college student, Erin Moran’s common peroneal nerve dysfunction, which could’ve prevented her from ever walking again.
Interview conducted by Ivanhoe Broadcast News in January 2022.
What brought Erin to you? What was she complaining of and how was she referred to you?
DR ALI: Erin and her mother were referred to me by the Chairman of Penn Neurosurgery, Dr. Daniel Yosher. He was asked by a medical colleague about Erin’s condition. The other physician wanted the best treatment for this young woman who had developed a dramatic neurologic deficit. Dr. Yoshor appropriately recognized that this may be a problem that involves the peripheral nervous system. I am one of a few peripheral nerve experts within our department at University of Pennsylvania so, Dan Yosher referred her to me. I, first, evaluated Erin and recognized that she had a severe deficit in her ability to walk, secondary to a foot drop. There are lots of reasons for foot drop. Essentially, her evaluation entailed starting from the drawing board, in terms of what the possibilities could be for why she would develop this weakness. Interestingly, Erin had described a history of having a fall in which she injured herself. It was a minor injury, I would note, but significant enough that the time course of that fall and her foot drop were very well correlated. Therefore, I suspected that she had developed common peroneal nerve dysfunction from that fall. We did additional testing to diagnose that and ultimately, that’s how I developed her treatment plan.
How quickly did her symptoms show after that injury and was this something that lingered or was it dramatic?
DR ALI: She developed her symptoms very quickly after the fall. Her deficit wasn’t a slow, progressive one. She had very dramatic weakness that was debilitating her day-to-day life. Erin is a young, active woman, and this kind of neurologic dysfunction was affecting her both from a functional standpoint as well as from a pain and sensory standpoint.
What did you do for her?
DR ALI: The first starting point was diagnosing the actual problem. In Erin’s case, it was pretty clear to me that this was not a problem emanating from her spine, which would be a very common reason why one may develop foot drop. I also considered but recognized that other inflammatory neurologic conditions were unlikely. So, we went ahead and got her tested with an EMG study. That allowed me to confirm the suspected diagnosis. The EMG helped localize the injury to the common peroneal nerve as it crosses the knee, which is a very common and vulnerable area that that nerve can get injured. The treatment plan I developed for her was first one of observation and physical therapy and ultimately, surgery when she was no better. I should note that there are many patients that do get better without surgical treatment. Often, we are following these patients very closely before we recommend surgery to see if they do get better on their own. Erin, unfortunately, was not one of those individuals. She continued to have severe and significant debilitation from her foot drop and therefore, I ultimately recommended surgery.
What do you have to deal with when you’re doing this kind of nerve surgery?
DR ALI: Common perineal nerve release is a very common procedure that I do as a neurosurgeon who specializes in spine and peripheral nerve surgery. Essentially, it’s an outpatient surgery in which we have the patient under some sedation. What we are doing is opening up the area along the side of the knee where that nerve can get entrapped under the muscle fascia, which are essentially tight bands of the muscle insertion. The nerve is traveling through a small tunnel in that space and I commonly explain it to patients as sort of the “carpal tunnel of the leg.” That nerve is an extremely delicate, vulnerable but important nerve. It’s one of the main drivers in our ability to lift our toes. When patients have dysfunction of that nerve, it can be extremely debilitating because their foot suffers a foot drop, which will limit their ability to walk, run and other activities. The nerve itself is several millimeters thick. Under loupe magnification and/or microsurgical technique, we release the nerve from the surrounding compressive elements and free up that nerve in a way that allows for electrical conduction to then be reestablished across the nerve. In surgery, I use adjuncts, such as direct electrical stimulation, so I can assess if that nerve able to conduct electrical current down to the muscle. That allows me to identify a healthy nerve versus a nerve that is diseased and not functioning properly. Those were some of the adjuncts that I used in Erin’s case.
Could you describe what you’re doing from the time you enter the knee?
DR ALI: I inject local anesthetic to numb the surgical site and then make a skin incision and dissect the soft tissues overlying the nerve. Once I identify the nerve, I electrically stimulate the nerve. Next , I proceed with what we call external neurolysis of the nerve, which is freeing the surrounding structures from the nerve and releasing the areas of nerve entrapment. In this case, there’s a muscle called the peroneus longus that has multiple fascial bands, which can compress the nerve as it tries to pass under these taut, thick structures. After that is accomplished, the soft tissues are then closed. The skin is then closed. We usually apply an ACE wrap around the leg and the patient then recovers from light sedation and anesthesia and ultimately goes home the same day. It’s not the kind of operation that patients immediately after surgery tend to have improvement in function. Nerve dysfunction still requires the body to recover and re-establish electrical conduction along the nerve’s entire length – in this case, down to the toes. True nerve regeneration can take about a millimeter a day to occur down to the target muscle. So, if you think about at the level of the knee down to the toes, it’s a significant distance. Therefore, I follow these patients up to six to 12 months to see what their full recovery and improvement from that surgery will look like.
What options would Erin have had prior to this surgery?
DR ALI: Unfortunately for a problem like this, there are not very good medical treatments. There’s no medication I could prescribe her to improve her foot drop. We rely on physical therapy and time or the body’s own ability to repair and recover nerve function. The longer nerve dysfunction exists, the longer the muscle and the joint are not moving , the higher the likelihood of formation of significant scarring and joint contracture which will limit the range of motion. Physical therapy can help with this. Many patients with common perineal nerve dysfunction, like Erin, often even get better with just physical therapy and time along as the body repairs the injury on its own. I often follow patients like Erin by performing serial examinations as well as using additional EMG tests to assess if and how well the body is repairing the nerve dysfunction.
Where is the nerve, exactly?
DR ALI: The common peroneal nerve stems off the sciatic nerve, which is the largest nerve of the human body. It travels down the back of the leg and then bifurcates and comes around the outside of the knee just under the fibular head . The common perineal nerve travels in a very vulnerable position there because it’s very superficial and only just a few tissue layers deep. It controls a very important function, both on the motor side as well as the sensory side. From a motor perspective, it is the main workhorse that helps your toes move up. That allows you to walk properly and controls the sensation along the lateral aspect of the distal leg. So, Erin actually had dysfunction from both a motor and sensory component, which clued me in to the fact that this was likely emanating from the common perineal nerve at this area.
How common is peroneal nerve dysfunction?
DR ALI: It is the most common nerve entrapment of the lower extremity. I’m a specialist in this area so, I see it more often than others. It tends to be a problem that is often misdiagnosed, unfortunately, because there are lots of reasons why one can develop a foot drop. A lot of patients will often be misdiagnosed as having spine disease that is causing their foot drop when indeed it’s a much more distal problem at the level of the peripheral nervous system.
At our Penn Nerve Center, we have expertise in the peripheral nervous system, from both a neurosurgical standpoint as well as from an orthopedic and plastic surgical standpoint. I think patients get the best level of care because our approach to these types of conditions is broad and this allows us to think very thoughtfully and carefully about where the lesion is. Once we can identify that, we can think about the appropriate treatment.
What does Erin going out to run a marathon say to you?
DR ALI: That is exactly the kind of outcome I love to see, and that’s why I do what I do. When I think about nerve dysfunction, I think of the nervous system in its continuity, starting from the brain to the spinal cord and down to the nerve roots and extending out to the peripheral nerves. At any point in that pathway, one could suffer damage and dysfunction, which could be severely debilitating. Erin is a young, active, healthy woman whose life changed completely with that nerve dysfunction. When we can identify the problem correctly and address it and give her that kind of result where she is back to running marathons, it is extremely gratifying. It’s really exciting for me to see someone like Erin who has the motivation and dedication to work towards her best potential after this kind of operation and maximize her recovery – I’m proud of her.
Are you the first female neurosurgeon?
DR ALI: I am the first female neurosurgeon at Pennsylvania Hospital. Since I completed my training at the University of Pennsylvania, there have been many more female trainees and it has been meaningful to me to mentor many of these young women. When I entered the field of neurosurgery, I did not have a female mentor. I had fabulous male colleagues and mentors who have undoubtedly taught me neurosurgical skills. Indeed, peripheral nerve surgery I learned though my fellowship with my mentor, Dr. Eric Zager, who has a very long-standing career in peripheral nerve surgery and is one of the world’s experts in this. However, I was lacking in having a female mentor. I am now not only a practicing academic neurosurgeon, but also a wife and mother of four sons. That part of my life is important to who I am and the kind of doctor I am for my patients. Therefore, I hope as my trainees go through their neurosurgical education and training, I can share pearls of wisdom that I’ve learned through the years as I continue to strive to be a better neurosurgeon and leader in this space.
What advice would you give to other women who are looking to enter a field that is traditionally dominated by men?
DR ALI: You need to follow your passion. If you have identified a passion that happens to be something in which you don’t see a lot of folks that look like yourself already doing – that’s OK. Forge ahead and if you work hard and care about what you do you will find a way to develop the skills you desire and ultimately be able to give that back to others.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
If you would like more information, please contact:
Kelsey Odorczyk
Kelsey.odorczyk@pennmedicine.upenn.edu
Sign up for a free weekly e-mail on Medical Breakthroughs called First to Know by clicking here
