Incidence of Traumatic Brachial Plexus Injuries in Sweden 2016–2020, a Nationwide Retrospective Cohort Study
This nationwide retrospective cohort study of 288 traumatic brachial plexus injuries in Sweden (2016–2020) reveals a total annual incidence of 0.57 per 100,000 and identifies two distinct clinical profiles: high-energy injuries predominantly affecting middle-aged men that frequently require nerve reconstruction, and low-energy injuries common in older adults associated with shoulder dislocations that rarely necessitate surgical intervention.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
The human arm is a marvel of engineering, powered by a complex network of nerves that branch out from the neck like the roots of a tree. When these nerves are damaged by a sudden, violent force, the result is a traumatic injury to the brachial plexus. This network controls the movement and sensation of the entire arm, so when it is torn or stretched, a person can lose the use of their hand and shoulder, often accompanied by severe, unrelenting pain. For decades, doctors have known that these injuries are rare but devastating, yet they have struggled to pin down exactly how often they happen or who is most likely to suffer them. Much of the existing data has been pieced together from different hospitals or based on broad codes that might miss the severity of the damage or include minor injuries that heal on their own. Without a clear, nationwide picture, it is difficult to plan how to best treat patients or where to send them for the specialized care they need.
To solve this puzzle, researchers in Sweden took a unique approach by looking at every single case of this injury across the entire country over a five-year period. Sweden had recently centralized its surgical care for these complex nerve injuries into just two specialized centers, one in Stockholm and one in Umeå. This meant that if a patient in Sweden needed surgery for a torn arm nerve, they would almost certainly end up at one of these two hospitals. The researchers, led by a team of hand surgeons, went through the medical records of everyone who was evaluated at these centers between 2016 and 2020. They did not just rely on computer codes; they personally reviewed the files to confirm that the injury was indeed a traumatic tear of the nerve network and not something else, such as a tumor or a minor nerve pinch that had already healed. They excluded people who were not permanent residents of Sweden to ensure their data was accurate for the local population.
What they found was a story of two very different types of injuries, each with its own distinct profile. Across the five years, they identified 288 confirmed cases, which translates to about 0.57 people out of every 100,000 Swedes getting this injury each year. The first group consisted of injuries caused by high-energy trauma, such as car crashes, skiing accidents, or falls from a significant height. These cases mostly happened to men in their early forties. For this group, the damage was often severe, frequently requiring complex surgery to reconnect or reroute the nerves. The second group was caused by low-energy trauma, typically simple falls from standing height or getting pinned down after a fall. These injuries happened to much older people, with an average age of over 62, and showed a more even split between men and women. Strikingly, most of these older patients had also dislocated their shoulder at the time of the fall. While the high-energy group often needed nerve reconstruction, the low-energy group almost never did; in fact, out of 135 cases in this category, only one person required surgery on the nerves themselves.
The researchers also noticed that the timing of these injuries followed the seasons, but in different ways for the two groups. The high-energy accidents peaked during the summer and early autumn, likely due to more outdoor activities and driving, and again in late winter, possibly linked to snow sports. The low-energy falls, however, were most common during the colder months from October to February, a time when icy surfaces make slipping more likely. The study also revealed that while both groups suffered damage to the nerves below the collarbone more often than above it, the pattern was especially strong in the older, low-energy group. This distinction is crucial because it suggests that doctors should not treat all arm nerve injuries the same way. A young man in a car crash needs a different plan than an older person who slips on ice.
By mapping out these clear differences, the study provides a roadmap for better care. It shows that while high-energy injuries are a crisis requiring immediate and often surgical intervention, low-energy injuries in older adults are usually managed without cutting into the nerves, focusing instead on rehabilitation and treating the broken bones or dislocated shoulders that often accompany them. The findings confirm that the way an injury happens tells doctors a great deal about what will happen next. This knowledge allows medical teams to direct patients to the right specialists faster and to set realistic expectations for recovery. While the study could not track how well patients felt or moved years later, it has successfully clarified the landscape of these injuries in Sweden, proving that understanding the cause of the trauma is the first step toward healing the damage.
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