Science / Medicine : Backpacks and Arm Paralysis

Hikers who carry around heavy, poorly adjusted backpacks that put pressure on their shoulders risk developing a temporary but “frightening,” paralysis of their arms, a doctor warned last week.

Dr. Patrick Rosario said he first noticed a syndrome he called “trekker’s shoulder” when he was hiking through the Himalayas in Nepal and came across a young man who could not move his right arm after a day spent walking down steep trails.

“The weakness started soon after he began a moderately steep descent, wearing a heavily laden, loosely slung backpack, and it became progressively worse by evening,” Rosario and Dr. Sylvia Fernandes said in a letter to the New England Journal of Medicine.

Rosario and Fernandes, staff members at Bronx Lebanon Hospital in New York, said the man had developed a condition known as “Erb’s palsy” in which nerves that travel from the neck through the shoulders and into the arms become stretched, often resulting in muscle weakness and numbness.

Fortunately, the condition is temporary and clears up without treatment if the pressure on the nerves is removed, he said. Rosario said the Himalayan hiker got better after a few days of rest and not carrying the backpack.