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ORIGINAL ARTICLE
Year : 2023 | Volume
: 14
| Issue : 1 | Page : 11-15
The carotid sheath route: An option to approach retrocarotid prespinal tumors with paravertebral extension
Filippo Gagliardi1, Leone Giordano2, Marzia Medone1, Silvia Snider1, Francesca Roncelli1, Edoardo Pompeo1, Pietro Mortini1
1 Department of Neurosurgery and Gamma Knife Radiosurgery, San Raffaele Scientific Institute, Vita-Salute University, Milan, Italy
2 Department of Otorhinolaryngology, San Raffaele Scientific Institute, Vita-Salute University, Milan, Italy
Correspondence Address:
Filippo Gagliardi
Department of Neurosurgery and Gamma Knife Radiosurgery, San Raffaele Scientific Institute, Via Olgettina 60, Milan 20132
Italy
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/jcvjs.jcvjs_148_22
Abstract
Background: The elective route to approach paravertebral lesions growing into the anterolateral lodge of the neck is widely recognized as the prespinal route with its two major variants. Recently, attention has been focused on the possibility of opening the inter-carotid-jugular window in case of reparative surgery for traumatic brachial plexus injury.
Aims: For the first time, the authors validate the clinical application of the carotid sheath route in the surgical treatment of paravertebral lesions expanding into the anterolateral lodge of the neck.
Methods: A microanatomic study was conducted to collect anthropometric measurements. The technique was illustrated in a clinical setting.
Results: The opening of the inter-carotid-jugular surgical window allows additional access to the prevertebral and periforaminal space. It optimizes the operability on the prevertebral compartment, compared to the retro-sternocleidomastoid (SCM) approach, and on the periforaminal compartment, compared to the standard pre-SCM approach. The surgical control of the vertebral artery is comparable to that obtained with the retro-SCM approach, while the control of the esophagotracheal complex and the retroesophageal space is comparable to the pre-SCM approach. The risk profile on the inferior thyroid vessels, recurrent nerve, and sympathetic chain is superimposable to the pre-SCM approach.
Conclusions: The carotid sheath route is a safe and effective option to approach prespinal lesions with retrocarotid monolateral paravertebral extension.
Keywords: Anterior prespinal route, carotid sheath route, operability, paraspinal tumors
Introduction 
The elective route to approach paravertebral lesions growing into the anterolateral lodge of the neck is widely recognized as the prespinal route with its two major variants: The pre- and retro-sternocleidomastoid (SCM) approach.[1],[2],[3],[4],[5]
The pre-SCM route allows for direct control of the esophagotracheal complex and the carotid sheath, which also represents the main limitation in the exposure of the lateral periforaminal compartment.
A recent anatomical study has focused attention on the possibility of splitting the carotid sheath by dissecting the loose connective and areal tissue lying between the common carotid artery (CCA) with the vagus nerve and the internal jugular vein (IJV); the technique was applied for the treatment of posttraumatic lesions of the brachial lower trunk.[6]
The authors, for the first time, demonstrate the clinical application of the carotid sheath route in the surgical treatment of paravertebral lesions expanding into the anterolateral lodge of the neck [Figure 1].
Figure 1: Schematic drawing showing the carotid sheath route. ASM - Anterior scalene muscle; C7 - C7; CCA - Common carotid artery; E - Esophagus; IJV - Internal jugular vein; NR - Nerve root; SC - Spinal cord; SCM - Sternocleidomastoid muscle; T = Trachea; TG - Thyroid gland; VN - Vagal nerveA microanatomic study was conducted to collect anthropometric measurements; the technique was illustrated in a clinical setting.
Methods Anatomic study
Five cadaveric specimens fixed with glutaraldehyde and injected with latex were used for the anatomical dissections.
The combined carotid-sheath route was performed on both sides.
For the anthropometric measurements, two targets were identified in the surgical field: the prevertebral and the periforaminal compartment.
The measurements were recorded and served as the basis for the final data.
Linear distances and angles were measured using a dedicated ruler and goniometer, respectively.
The depth of the surgical field (D) was considered as the working distance on one of the target points from the skin level.
The maneuverability arc (MAC) and surgical angle of attack (SAA) were defined as the degree of freedom in manipulating surgical instruments and the angle of incidence of the surgical corridor and were calculated at the different target points, respectively.[7]
Surgical technique
The patient is positioned supine with the neck extended and the head rotated to the contralateral side.
A skin incision is performed along the anterior margin of the SCM. The platysma is divided, and the SCM comes into view. A gentle muscle retraction is performed, exposing the medial margin of the IJV, which partially overlies the CCA at this level.
The loose and areolar connective tissue between the CCA and the IJV is gently dissected, dividing the artery together with the vagal nerve and the sympathetic chain, which are kept medially from the vein, which is kept laterally, thus opening the inter-carotid-jugular window.
Further deep dissection through the fat in the sheath leads to the surface of the anterior scalene muscle and intervertebral foramen.
In this step, care should be taken in identifying possible arterial branches, or venous tributaries, crossing the passage between the IJV and the CCA.
The vertebral and inferior thyroid vessels, the sympathetic chain, and the recurrent laryngeal nerve lie deep to the CCA; thus, by remaining lateral to the CCA, injury to these structures should be avoided.
Results The anthropometric measurements collected during cadaveric dissections are summarized as mean values and standard deviations in [Table 1].
The clinical case of a schwannoma of the inferior trunk of the left brachial plexus is reported and illustrated to demonstrate the surgical feasibility of the technique [Figure 2] and [Figure 3].
Figure 2: Preoperative MRI (a and b) and tumor appearance after resection (c). MRI - Magnetic resonance imaging
Figure 3: Intraoperative view. (a) Carotid sheath exposure; (b) Opening of the carotid sheath; (c) Tumor resection through the inter-carotid-jugular window. CCA - Common carotid artery; IJV - Internal jugular vein; MA - Mandibular angle; SCM - Sternocleidomastoid muscle; T - Tumor; VN - Vagal nerve Discussion The elective approach for the surgical management of brachial plexus lesions with prescalene and extra-canal extension is widely recognized as the anterior prespinal approach in its variants.
It allows easy exposure of the median prevertebral space and the paramedian compartment up to the anterior periforaminal area.
The selective section of the scalene muscle ensures further surgical control over the proximal extraforaminal space.[2],[5],[8]
Lesions with prevalent growth in the anterolateral lodge of the neck have always been the subject of debate regarding the comparative evaluation of the pros and cons of the pre- and retro-SCM pathways, each of them with its own supporters and detractors.[1],[2],[3],[4],[5]
The pre-SCM pathway takes advantage of direct control of the carotid sheath and the esophagotracheal complex without the need to manipulate the distal motor branches of the spinal accessory nerve. The potential risks of iatrogenic damage do involve the inferior thyroid vessels, the recurrent nerve, and the sympathetic chain.
The lateral exposure is limited by the carotid sheath itself. Prolonged traction is not recommended because it can cause direct vascular lesions, ischemic damage on an embolic or compressive basis, and direct damage to the vagal nerve.
A recent anatomic study has focused attention on the possibility of opening a working window through the carotid sheath for the neurotization in posttraumatic damage of the inferior trunk of the brachial plexus.[6]
For the first time, the authors describe the application of the carotid sheath route in neck oncological surgery; the technique was applied in the case of prevertebral lesions with unilateral extra-foraminal median and paramedian extension.
The opening of the inter-carotid-jugular surgical window allows additional access to the prevertebral and periforaminal space with a multidirectional corridor; this optimizes the operability on both compartments in terms of surgical maneuverability and angle of incidence of the surgical corridor on the target structures. In particular, compared to the retro-SCM approach, the carotid sheath route ensures a better MAC and SAA on the prevertebral compartment while optimizing MAC and SAA on the periforaminal compartment as compared to the standard pre-SCM approach.
The surgical control of the vertebral artery (laterally) is superimposable to the retro-SCM approach, while medially, the control on the esophagotracheal complex and the retroesophageal space is comparable to the pre-SCM approach.
The direct access to the anterior scalene muscle allows exposure of the proximal extra-foraminal area by selective sectioning of muscle fibers, providing a more favorable angle of incidence of the surgical corridor than in the retro-SCM approach. The latter does, instead, ensure better surgical visualization of the proximal extraforaminal compartment.
The risk profile on the inferior thyroid vessels, recurrent nerve, and sympathetic chain is comparable to the pre-SCM approach.
The comparison between the different approaches is depicted in [Table 2].
In conclusion, the carotid sheath route is a technique that allows the implementation of operability and exposure in the pre-SCM anterior approach, improving surgical control over the periforaminal compartment without increasing the morbidity profile of the standard anterior prespinal route.
Conclusions The carotid sheath route is an option to approach brachial plexus lesions with prescalene and extra-canal extension. It allows effective exposure of the median prevertebral space and the paramedian compartment up to the anterior periforaminal area, increasing operability on the latter, compared to the standard pre-SCM approach.
Surgical control of the vertebral artery, esophagotracheal complex, and retroesophageal space empowers the safety profile of the approach.
We advocate the application of the carotid sheath route in the case of prespinal lesions with retrocarotid monolateral paravertebral extension.
Ethical standards
This article does not contain any studies with living human participants or animals performed by any of the authors.
Financial support and sponsorship
Nil.
Conflicts of interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers' bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or nonfinancial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.
References 
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