Neck Muscle Strength Linked to Movement Performance in Duchenne MD Boys

The strength of neck-flexing muscles not only affects torso movements but also the overall daily performance of children with Duchenne muscular dystrophy (DMD), a study has found.

A key implication is that taking steps to maintain neck muscle strength early in the disease may improve the children’s movements.

The research also suggested that neck muscle strength tests might be used to assess overall physical performance in patients who are still able to walk, without subjecting them to tiring tests.

The study, “Neck flexor muscle strength and its relation with functional performance in Duchenne muscular dystrophy,” was published in the European Journal of Paediatric Neurology.

Neck-flexing muscles are used when the head is tipped forward. Earlier studies have shown that the muscles are crucial for a person who is lying down to be able to sit and stand. Studies have also suggested that lack of strength in these muscles impacts the Duchenne patients’ trunk functions.

Researchers at Hacettepe University in Turkey hypothesized that the impact of weak neck muscles might go beyond trunk movements. They recruited 70 boys with DMD to study whether neck muscle strength is linked to patients’ overall physical performance, or daily life function.

The research team divided the boys into two groups, based on neck muscle strength. The average age was 7–8 years in both groups, and there was no difference in how well they could walk.

Patients with better lower neck muscle strength performed worse on the six-minute walk distance test and the North Star Ambulatory Assessment (NSAA), which measures ambulatory capacity in Duchenne patients.

Analyses showed that neck muscle strength and six-minute walk distance were correlated, as were muscle strength and NSAA scores. However, there was little correlation between muscle strength and the time it took the boys to stand up from a prone position.

The findings support the idea that neck-flexing muscles are important for daily life activities, particularly those requiring endurance. In contrast, researchers found that neck muscles had less impact on short-duration movements.

Researchers suggested that measures of neck-flexing muscle strength could be used instead of tiring exams like the six-minute walk test to assess overall physical performance of Duchenne patients.

“Approaches for maintaining the muscular strength of neck flexors from the early stages of the disease are thought to have an effect on functional performance by decreasing compensations and effort in daily activities,” they concluded.