IT would seem based on this that the at least half and maybe a majority of people have abnormalities that predose them to TOS. According to a recent study, about 70% of repetitive strain injuries are TOS. Maybe people who require surgery for TOS have more severe abnormalities than normal?

Am J Surg. 1995 Jul;170(1):33-7.

Comment in:
Am J Surg. 1995 Nov;170(5):524.

Anomalies at the thoracic outlet are frequent in the general population.
Juvonen T, Satta J, Laitala P, Luukkonen K, Nissinen J.

Department of Surgery, University of Oulu, Finland.

BACKGROUND: Abnormal anatomy at the thoracic outlet is frequent in patients operated on for thoracic outlet syndrome (TOS). The present study was designed to find out the rate of thoracic outlet anomalies in the general population. METHODS: Fifty cadavers representing a general population were subjected to a total of 98 meticulously performed cervical dissections to ascertain the frequency of congenital anomalies in the thoracocervicoaxillary region. RESULTS: During the 98 cervical dissections, 62 instances of abnormal anatomy of the thoracic outlet were found, and fully normal anatomy was found in 36 cases. Of the total 69 abnormalies, 66 could be classified according to Roos: 37 were type 3 abnormalities, 15 were type 5, 9 were type 11, and there was 1 each of type 4, type 6, type 7, type 9, and type 10 abnormalities. The remaining 3 abnormalities did not fit into Roos' classification. Only 10% (5/50) of the cadavers had a bilaterally normal anatomy. CONCLUSIONS: The results demonstrate that abnormal structures, such as congenital bands in the thoracic outlet, are more common in the general population than had previously been described. We suggest that fibrous bands confer a predisposition for TOS following a certain degree of stress or injury.





A comparative study of structures comprising the thoracic outlet in 250 human cadavers and 72 surgical cases of thoracic outlet syndrome.
Redenbach DM, Nelems B.

School of Rehabilitation Sciences and Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, Canada.

OBJECTIVE: We have hypothesized that variations in fibrous, muscular and osseous structures with the potential to entrap the brachial plexus occur within the thoracic outlet of the normal population; and that these variations are different in pattern and frequency from those in patients presenting with thoracic outlet syndrome (TOS). METHODS: Structural anomalies with potential for entrapping elements of the brachial plexus were examined following dissections of the posterior triangle of the neck in 250 human cadavers (N = 500 thoracic outlet dissections) and catalogued jointly by an anatomist and a thoracic surgeon. The pattern and frequency of anomalies in the 250 cadavers was compared to that encountered in 72 surgical cases of removal of the first rib for relief of symptomatic TOS (N = 72 procedures, 55 patients). RESULTS: Relevant structural variations were encountered in 46% of cadavers, exhibiting no left right or gender preference overall. When compared with the surgical group in which 100% exhibited structurally relevant anomalies, significant differences in pattern of anomalous structures and gender distribution were revealed. Anomalies posterior to the brachial plexus, ranging from fibrous bands to cervical ribs in both groups, were prevalent in the surgical group. A 'scissors-like' pattern, with neural entrapment by anterior and posterior anomalies was frequently encountered in females. CONCLUSIONS: Based on these data and embryological considerations, we propose a revised and simplified classification of impingement mechanisms within the anatomic thoracic outlet. Comparing these data to radiological imaging and observations at surgery, we offer a new perspective for the investigation and management of patients with TOS.

PMID: 9641331 [PubMed - indexed for MEDLINE]