"He's just a handful - three is crazy," his mother, Lynn Russell, said over the phone. "He always has talked a lot. Now he has entered the realm of debating me."

The sassy toddler is one of 90 children with spinal muscular atrophy taking the drugs carnitine and valproic acid as part of a clinical trial run by Salt Lake City neurologist Kathryn Swoboda. He has high energy these days - and he's stronger and has better mobility, too.

Lynn believes it's due in part to the drug combination being studied in the yearlong clinical trial, which Liam finished participating in last month.

"A year ago when we went, I think he was starting to lose some function," she said. "He wasn't rolling very much. He was just more sloppy. He uses this wrist and manual stander and he was pretty much never in it."

Now Liam spends between three and five hours in his stander every day, which, "to me, that's the biggest improvement," Lynn said. The toddler also is able to stand up and sit down with more control and can roll himself over.

"He can roll sort of indefinitely if he feels like it," his mother said. "He can roll through the whole house if he wants to."

For the past six months, all 90 children participating in the study have been on the drugs. During the first six months, however, half were on placebos. Neither the patients and their families nor Swoboda know which children - at six sites around the country - received the drugs in the first six months.

Valproic acid, approved by the Food and Drug Administration to treat epilepsy, psychiatric disorders, migraine headaches and pain, has also been shown to increase the protein critical to the health of motor neurons, or nerve cells in the spinal cord. The carnitine - a nutrient that helps the body turn fat into fuel - replaces that which is depleted by the valproic acid.

Swoboda, an assistant professor at the University of Utah School of Medicine, is the principal investigator of the $2.5 million clinical trial to study the drugs' effectiveness. Slated to wrap up in November, the study will help determine whether the drugs help salvage the nerves of children like Liam, who have Type 2 SMA.

Lynn believes her son was among the half who have been taking the carnitine and valproic acid the entire time.

Since last year, Liam's bone density has increased 14 percent, in part due to the frequent use of his stander. The stander serves as a weight-bearing exercise, allowing Liam to also do trunk rotations and arm movements.

Though Liam has completed Swoboda's clinical trial, the Russells have decided to keep him on the medications due to the improvements they've seen. "We're actually going to increase his dosage a little bit because he's grown quite a bit," Lynn said.

Swoboda said she is "really pleased with how the trial has gone in general," but added, "We've had the typical sort of adverse events you'd expect along the way because these kids are sick kids."

Among those side effects are weight gain, which can be problematic for SMA children who are already weak and struggle to move around, Swoboda said. Liam gained weight during the trial, his mother said, but he is also growing, making it difficult to attribute the weight gain to the drugs alone.

Because valproic acid and carnitine are already FDA-approved, Swoboda said, the purpose of the study is to see if the drugs work specifically for SMA patients. If so, they could be used along with a mix of other treatments - including stem cell therapy.

"We're excited about this medication, but we also want to make sure we're recommending the right thing for our patients by thoroughly looking at the issue," Swoboda said.

The neurologist plans to continue researching how effective the drugs are in patients with other types of SMA.

By the end of this trial, however, she hopes to answer the question "Does this improve their [Type 2 SMA patients'] function, yes or no?"

Lynn is optimistic the valproic acid and carnitine will help Liam, but she's not expecting a miracle.

"I don't think he's going to get up and walk," she said. "To me it's more important he stays healthy. Of course I would like for him to walk and run, but . . . that doesn't necessarily need to be the goal."

lrosetta@sltrib.com

The scoop on SMA

* Q: What is spinal muscular atrophy?

* A: SMA affects motor neurons, or nerve cells in the spinal cord, that send fibers out to control muscles throughout the body. Those cells need certain proteins to stay healthy. In people with SMA, the gene that produces those proteins is missing or mutated. The crippling genetic disorder affects the voluntary muscles used in crawling and walking, as well as those in the chest wall used in breathing and coughing. For that reason, SMA can lead to pneumonia and other lung problems.