Spinraza stabilizes spinal muscular atrophy

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Spinal muscular atrophy, or SMA, is a rare degenerative muscle disease. Patients are missing the nerve cells in the spine that tell muscles to move.

Until now, doctors could only treat symptoms. But a recently approved drug and a new delivery system are giving people hope.

Shawn Stewart was diagnosed with spinal muscular atrophy when he was 3.

"I was walking until the age of 13. I broke my leg at that age. After that, I was no longer able to walk," Stewart said.

He lost function in his arms, legs and back. Just breathing became difficult.

For more than 45 years, doctors only treated his symptoms. Then in 2016, the Food and Drug Administration approved Spinraza, a drug that increases production of the survival motor neuron protein needed for muscle control.

"I've had patients that had no arm function that can now move their arms," neurosurgeon Dr. Michael Muhonen said. "I've had patients that were ventilated, couldn't breathe on their own, and they can now breathe."

The problem was that many SMA patients like Stewart have had spinal fusion. Giving the drug through a spinal tap three times a year was painful and potentially dangerous. So, Muhonen came up with a new way of administering it.

"This is a port that allows us to inject the Spinraza through this tube, which has 20 holes in the tip of it. This tube goes into the spinal fluid," Muhonen said.

"It makes the injections so easy. It takes five to 10 minutes to get the injection, and I'm able to do that sitting up in my wheelchair," Stewart said.

Shawn says in a year and a half on Spinraza, his breathing and speech have improved. And since Muhonen's port simplifies drug delivery, he has high hopes

A company in Boston is working on improvements to Muhonen's port right now. He believes delivering the drug in the upper body and having it drip down through the spine will prove to be more effective than having the drug move up from a lumbar puncture.

REPORT: MB #4603

BACKGROUND: Spinal muscular atrophy, SMA, affects the part of the nervous system that controls voluntary muscle movement, such as moving an arm or a leg. SMA is a genetic disease and it gets its name because most of the nerve cells that assist us in muscle movement are located within the spinal cord. SMA primarily effects the muscles. The nerve cells within the spine are not able to send signals to the muscles. SMA has four types that are classified from 1 through 4. This is because the age of onset, symptoms and rate of progression is different in different individuals. SMA kills the most children compared to any other genetic disease and is estimated to occur in 1 out of every 6,000 births. (Sources: https://www.mda.org/disease/spinal-muscular-atrophy & https://thegsf.org/press/detail/what_is_spinal_muscular_atrophy_sma/)

TREATMENT: Before Spinraza the only real way that SMA was treated was by treating the symptoms. This was done by using assistive devices such as ventilators to help patients who couldn't breathe on their own anymore due to the SMA. Spinraza now allows doctors to treat the disease itself and really give patients a fighting chance against a rare disease. It can help either delay, prevent, or reverse the symptoms. Spinraza is administered through an injection into the spine. Michael Muhonen, MD, Neurosurgeon, Head of Neurosurgery at Children's Hospital of Orange County at St. Joseph Hospital believed there had to be an easier way to administer the drug to elderly patients instead of only doing a spinal tap. "When you have to do a spinal tap, you have to put the patient on their side typically, curl them up in a ball. There are case reports of patients having broken femurs and dislocated hips merely from trying to do this procedure which is very difficult in a very fragile patient," said Muhonen. (Source: https://www.medicalnewstoday.com/articles/192245.php & Michael Muhonen, MD)

NEW TECHNOLOGY: Dr. Muhonen says the current way of injecting the Spinraza might not be the most effective. "When you give the drug in the lower back region, you're flooding the drug in the system or all the nerve roots hang down off the spinal cord. You hope that the drug circulates uphill and attacks these areas or latches onto these areas where it will be more effective," said Muhonen. So, he wanted to create a device that could get the drug closer in proximity to these anterior horn cells. Muhonen crated a device with a lumbar spine catheter and a vascular port that could do just that, "The goal with this was to get something small like this and the tube is very small such that I could put that in the spinal column and there's 20 holes on the end of this and let the fluid drip out of this down the spinal cord, and at the same time making it so I didn't have to move the patient outside of their wheelchair." (Source: Michael Muhonen, MD)