Original articleInjury mechanisms in supraclavicular stretch injuries of the brachial plexusMécanismes traumatiques dans les lésions supraclaviculaires étendues du plexus brachial
Introduction
Traumatic brachial plexus injuries (BPI) are a consequence of traction forces that result in nerve ruptures or root avulsions [1]. Traction forces can be generated by direct or indirect trauma to the shoulder girdle [2]. Depending on the type of trauma, variable patterns of BPI can occur. Theories about the injury mechanism correlating the pattern of plexus injury and type of palsy were established in middle 19th century and continue to persist with scarce contemporary contributions [3].
We investigated the injury mechanisms involved in BPI in a cohort of patients and found that they differed significantly from the classical concepts.
Section snippets
Patients and methods
From September 2006 to June 2009, 150 consecutive patients with supraclavicular lesions of the brachial plexus were prospectively evaluated and operated at our hospital. All except four were male. Their average age was 26.8 years (SD ± 9.3 months) and the interval between their accident and surgery was 5.4 months on average (SD ± 2.8). Prior to surgery, patients were examined clinically and underwent a helical CT-myelogram following intradural contrast product injection.
Patients were asked about
Results
Among the 150 patients, 57 of them remembered enough details of their accident and provided us with sufficient information to allow for analysis of the shoulder trauma. The accident data are summarized in Table 1. None of the patients was able to provide information about the position or movement of their head during the trauma.
Discussion
In late 19th century, cadaver studies showed that brachial plexus injuries could not be provoked by the impact of the clavicle on the brachial plexus and first rib, but instead were due to neural traction [1]. Afterwards, the mechanical factors determining the level of injury were described. Barnes (1949) stated that root plexus injury was due to separation between shoulder and head, while the arm position at the moment of the collision determined which roots were injured [3]. With the arm
Conclusion
We speculate that lesions of the C5 and C6 roots follow shoulder depression by a direct impact force, whereas those involving C7-T1 mostly occur from posterior forceful retropulsion of the shoulder girdle by a compressive force. Sudden depression of the shoulder can injure all the roots, as we observed in patients who were hit by a falling tree branch that struck their shoulder and caused multiple fractures.
Disclosure of interest
The authors declare that they have no competing interest.
Acknowledgements
Ernesto Ernirock for his patience and brilliance while making the drawings.
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