Anatomical Bases of Thoracic Outlet Syndrome
Seance of wednesday 17 october 2018 (Chirurgie de la main et du membre supérieur)
Abstract
Communication between the neck and chest on one side and the root of the upper limb on the other is established through osteo-fibro-muscular or narrow passageways. These passageways belong to the regions: 1) Supra-clavicular; 2) Lung apex; 3) Costo-clavicular; 4) Axilla.
Many nerve and vascular structures pass through these passageways in both directions.
For 40 years we have been studying these passages, both morphologically and dynamically, in the living (during operations) and in the corpse (through dissections and functional tests).
These studies allowed us to determine:
-That these passageways are extremely variable in number, arrangement, shape and size.
-That the classical descriptions do not reflect these variations.
-That several intraoperative findings are misinterpreted as anomalies, when they are, conversely, mere anatomical variations.
-For an anatomical variation to produce real compression, it must narrow a passage and, often times, associate with an extreme position of the shoulder girdle maintained over time.
-Throughout this research, we have identified the following passages, which may be the cause of neurovascular compressions:
The passageways of the supra-pleural membrane
-T1 passageways or buttonhole ;
-C8-T1 passageway.
The Scalene passageways
-Posterior Interscalene Passageway, neural (C8-T1) ;
-Anterior Interscalene Passageway
*Superior Level, neural (C5-C6) ;
*Middle Level, neural (C7) ;
*Inferior Level, vascular (Subclavian Artery).
-Pre-scalene Passageway (Subclavian Vein)
The costo-clavicular passageways
-Lateral costo-clavicular passageways (Subclavian Artery + Brachial Plexus Cords) ;
-Medial costoclavicular passageway (Axillo-subclavian Vein).
Axillary passageways
-Retro-Pectoralis Minor passageway ;
-Pre-humeral head passageway. "Median nerve “Y” passageway ;
-Langer’s axillary muscle passageway.
-The main structures and variations that can produce compressions:
-The costo-septo costal ligament at the T1 buttonhole ;
-The transverse-septo-costal ligament at the C8-T1 passageway ;
-The Scalene Minimus impinging on C8-T1 (backward) or on the subclavian artery (forward) ;
-The Upper Intermediate Scalene (against C7) ;
-A sharp edge of the Middle Scalene impinging on the Lower Trunk of the Plexus Brachial ;
-An abnormal cervical rib (developmental bone abnormality not included in this study).
-Main unnatural positions that can produce neurovascular entrapments:
-Hyper-elevation of the arm (by the medial or Caldani coracoclavicular ligament) ;
-Descent of the shoulder girdle in relation to the thorax (by stretching and bending of the C8-T1 roots around the 1st rib).
Many nerve and vascular structures pass through these passageways in both directions.
For 40 years we have been studying these passages, both morphologically and dynamically, in the living (during operations) and in the corpse (through dissections and functional tests).
These studies allowed us to determine:
-That these passageways are extremely variable in number, arrangement, shape and size.
-That the classical descriptions do not reflect these variations.
-That several intraoperative findings are misinterpreted as anomalies, when they are, conversely, mere anatomical variations.
-For an anatomical variation to produce real compression, it must narrow a passage and, often times, associate with an extreme position of the shoulder girdle maintained over time.
-Throughout this research, we have identified the following passages, which may be the cause of neurovascular compressions:
The passageways of the supra-pleural membrane
-T1 passageways or buttonhole ;
-C8-T1 passageway.
The Scalene passageways
-Posterior Interscalene Passageway, neural (C8-T1) ;
-Anterior Interscalene Passageway
*Superior Level, neural (C5-C6) ;
*Middle Level, neural (C7) ;
*Inferior Level, vascular (Subclavian Artery).
-Pre-scalene Passageway (Subclavian Vein)
The costo-clavicular passageways
-Lateral costo-clavicular passageways (Subclavian Artery + Brachial Plexus Cords) ;
-Medial costoclavicular passageway (Axillo-subclavian Vein).
Axillary passageways
-Retro-Pectoralis Minor passageway ;
-Pre-humeral head passageway. "Median nerve “Y” passageway ;
-Langer’s axillary muscle passageway.
-The main structures and variations that can produce compressions:
-The costo-septo costal ligament at the T1 buttonhole ;
-The transverse-septo-costal ligament at the C8-T1 passageway ;
-The Scalene Minimus impinging on C8-T1 (backward) or on the subclavian artery (forward) ;
-The Upper Intermediate Scalene (against C7) ;
-A sharp edge of the Middle Scalene impinging on the Lower Trunk of the Plexus Brachial ;
-An abnormal cervical rib (developmental bone abnormality not included in this study).
-Main unnatural positions that can produce neurovascular entrapments:
-Hyper-elevation of the arm (by the medial or Caldani coracoclavicular ligament) ;
-Descent of the shoulder girdle in relation to the thorax (by stretching and bending of the C8-T1 roots around the 1st rib).