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February 26, 2020

Team of Mayo Experts Pinpoints Source of Puzzling Leg Weakness

By SharingMayoClinic
Without an explanation for progressive weakness in his legs, Raymond Knapp was resigned to the notion that he would be confined to a wheelchair. A collaborative effort among Mayo Clinic specialists in Radiology and Neurology, though, changed everything for Raymond, giving him the diagnosis and treatment he needed to walk on his own again.

Without an explanation for progressive weakness in his legs, Raymond Knapp was resigned to the notion that he would be confined to a wheelchair. A collaborative effort among Mayo Clinic specialists in Radiology and Neurology, though, changed everything for Raymond, giving him the diagnosis and treatment he needed to walk on his own again.


Believing he was headed toward a future in which he would be unable to walk much, if at all, Raymond Knapp was anxious to find answers when he arrived at Mayo Clinic. Due to progressive weakness in his legs, Raymond and his wife, Ruth, had begun to look at wheelchairs and an accessible van. "I was convinced that I was going to spend the rest of my life in a wheelchair," he says.

Raymond's decline had been swift, and he was shocked by the change. Just several years earlier, he had been physically active, participating in a variety of sports, including basketball, softball and racquetball. "I went from my early 60s playing all sports, moving around freely and chopping down trees to where walking around unassisted was difficult," Raymond says.

As the weakness worsened, Raymond progressed from having no problems with his mobility to needing a cane to requiring a walker. Eventually, he had to have two people help him when he wanted to stand. He also experienced numbness, burning, tingling and sensory loss in his feet and legs. Raymond found himself becoming weaker, even losing the ability to urinate on his own.

Raymond's doctors had diagnosed him with a neurological problem, but that didn't explain the loss of strength in his legs. And despite medications and surgery, his legs continued to weaken. Then he started having severe sciatic nerve problems in his right leg. His physicians were stumped as to what caused Raymond's muscle and nerve degeneration, and they referred him to Mayo Clinic for further evaluation.

By the time of that referral, Raymond had undergone a surgical procedure to alleviate what was diagnosed as neck cord compression. When his symptoms continued to worsen, he underwent six months of IV steroid and immunoglobulin therapy for suspected viral myelitis. None of it helped, and Raymond was desperate for something that could cure his partial paralysis

Mayo physicians team up

At Mayo Clinic in Rochester, a team of experts was ready to help. Harry Cloft, M.D., Ph.D., Neurointerventional Radiology; Christopher Klein, M.D., Neuromuscular Medicine; Marcus Pinto, M.D., a resident in the Department of Neurology; Kirk Welker, M.D., Neuroradiology; and Meagan Uzee, M.D., a Neuroradiology fellow, came together on Raymond's care team.

"Patients may come in with bladder incontinence and stiffness in their legs, and a diagnosis can easily be missed," Dr. Klein says. "It takes conversations between specialists in different areas to really identify what is going on."

"We strive to perform the best-quality imaging exams, so that we can work with our colleagues in Neurology to reach the right diagnosis and treatment."

Kirk Welker, M.D.

Based on results from several tests and examinations, the care team agreed that Raymond had a fluid-filled cavity, called a syrinx, in his spinal cord, as well as a possible vein abnormality. Both could be contributing to some of Raymond's symptoms, including toes that were pointing up and reduced reflexes — little movements of the muscle that occur when a tendon is tapped. But Dr. Klein says he was puzzled because these results were contrary to typical spinal cord injuries, which usually cause increased reflexes.

Drs. Klein and Pinto believed that another problem — a fistula — was more likely to be at the heart of Raymond's medical concerns, and they asked Drs. Welker and Uzee to perform and interpret additional MRI scans. Results from those tests showed that Raymond likely had a dural spinal arteriovenous, or AV, fistula, which is an abnormal connection between a vein and an artery in the spine. Based on that, Drs. Welker and Uzee recommended that Raymond undergo an angiogram.

"We're fortunate to have high-quality spinal MRI at Mayo Clinic, which can help us in making diagnoses that previously proved elusive," Dr. Welker says. "We strive to perform the best-quality imaging exams, so that we can work with our colleagues in Neurology to reach the right diagnosis and treatment."

Accurate diagnosis, effective treatment

Dr. Cloft performed a diagnostic angiogram on Raymond's spine. The test is a sophisticated examination, but it's a minimally invasive procedure that requires only a small incision in the skin of the groin through which a catheter is advanced into the artery.

Based on the results of the angiogram, Dr. Cloft confirmed that Raymond had a dural spinal arteriovenous fistula, and it was the root cause of his symptoms. The fistula had caused the vein to become congested. That led to fluid collecting in the spinal cord. The syrinx then expanded, causing injury in the spinal cord. As a result, multiple nerve roots were damaged, triggering pain, weakness and sensory loss.

"To have the kind of spinal cord fluid collection the patient had secondary to a dural spinal AV fistula is pretty rare. I think there have only been two other cases in the medical literature," Dr. Cloft says. "We see patients with similar fistulas probably once or twice a month, but his was a little bit harder to diagnose. The patient's syrinx in this case is really what was odd."

While Raymond was still in the procedure room for the diagnostic angiogram, Dr. Cloft was able to transition to treating the fistula through the same small access site in the groin. He performed an embolization by carefully advancing the catheter to the artery and injecting a type of glue to block the abnormal connection between the artery and a vein in the lumbar spine area. This treatment reduced the size of the syrinx, allowing the spinal cord injury to heal.

"(The patients) are always happy to have an answer, but they are even happier that the answer comes along with a treatment that works."

Harry Cloft, M.D.

The treatment worked. A follow-up MRI three months later showed the fluid in the syrinx had disappeared. Although Raymond still was experiencing urinary retention at that point, he had started to notice his legs regaining strength and becoming more stable.

"It's rewarding to treat someone like Raymond and help them get better. A lot of these patients are desperate for a diagnosis because they're gradually losing strength, and oftentimes they haven't gotten the answer someplace else," Dr. Cloft says. "They are always happy to have an answer, but they are even happier that the answer comes along with a treatment that works."

If not for the diagnosis he received at Mayo Clinic, the decreased blood flow in Raymond's spinal cord may have continued. Eventually, it could have led to complete paralysis. "Raymond probably would've gotten worse," Dr. Cloft says. "At some point, if you don't treat patients, they might not recover. The longer the spinal cord is congested, the more likely they're not going to get a good recovery. So it is important to make the diagnosis in a timely matter."

Because of collaboration between neurologists and radiologists, patients like Raymond can find hope through Mayo Clinic. "It's a team approach. Sometimes it's not so obvious. Sometimes it's subtle," Dr. Klein says. "In the future, when imaging shows a syrinx, and it is unclear why, physicians should consider that there may be an occult dural spinal AV fistula. This is a new indication for thinking."

From wheelchairs to road trips

Raymond never lost hope during his care, as he believed every physician involved was doing everything that could be done. "I'm just very grateful for all the doctors, that they were persistent in trying to figure out what was wrong. I guess the only thing I'm sorry about is that I didn't recognize that I was sick for a long time," Raymond says. "Maybe that's a trigger for other older people that sometimes as you age, you think it's just old age, but maybe it's not."

"I'm out there living life. The happy ending to this story is I'm out kicking around."

Raymond Knapp

Now retired, Raymond spends much of his time exercising, doing yardwork, traveling and spending time with his grandchildren. Although some symptoms persist, such as increased nerve sensitivity in his legs and feet, and he still needs the assistance of a walker, Raymond is glad he is not in a wheelchair.

"I'm out there living life," he says from the road, on a trip with Ruth. "The happy ending to this story is I'm out kicking around."


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Tags: Dr. Christopher Klein, Dr. Harry Cloft, Dr. Kirk Welker, Dr. Marcus Pinto, Dr. Meagan Uzee, Dural arteriovenous fistula, Neurology & Neurosurgery, Radiology

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