Abstract
This study provides a single-center experience involving intracapsular dissection for Shamblin II carotid body tumors (CBTs) and compares the outcomes with the classic technique of subadventitial resection. Based on the preliminary results, it seems that the enucleation technique facilitates the dissection of carotid body tumors, offering protection to cranial nerves and the internal/external/common carotid artery by utilizing the capsule as a barrier. The classic subadventitial resection approach and the enucleation technique have comparable postoperative complications. However, it is crucial to continue following the patients who underwent these resection techniques to determine the long-term outcomes. Moreover, the enucleation technique significantly reduces surgery duration and intraoperative blood loss.
Keywords: Carotid body tumors, Paragangliomas, Intracapsular dissection, Enucleation technique, Subadventitial dissection
Paragangliomas are neoplasms that arise from neuroectodermal tissue during the embryonic period and are distributed along the sympathetic and parasympathetic chains of the body. While primarily situated in the adrenal glands, paragangliomas can be sporadically identified in different areas of the body. The head and neck region are the most common sites for extra-adrenal paragangliomas, with the carotid body being the most frequently affected site for the detection of these tumors [1].
The carotid body is located within the carotid adventitia at the posterior aspect of the carotid bifurcation. Paraganglionic cells in this region can give rise to a vascular neoplasm known as a carotid body tumor (CBT). About 65% of paragangliomas in the head and neck region manifest as CBTs. Typically, cases of CBTs are asymptomatic and are often incidentally discovered during routine physical examinations or imaging studies [2]. While these tumors typically exhibit a slow growth rate, there is a potential for eventual invasion of cranial nerves, leading to subsequent complications. Observation may be suitable, especially in older patients with a high risk of operative and anesthesia complications; nevertheless, treatment is typically recommended [1, 3, 4]. Treatment options, including surgery or radiotherapy, are considered based on various factors. Generally, surgical resection is regarded as the primary treatment for most cases of CBTs [4].
Subadventitial resection is a recognized surgical technique for addressing CBTs. Nevertheless, this method is associated with certain drawbacks, such as relatively high rates of temporary or permanent nerve injuries, an extended duration of surgery, and a potential risk of injury to the media layer of the adjacent vessels. The anatomical intricacies of the head and neck region, its proximity to the central venous system and nerves, and its rich arterial vasculature collectively pose technical challenges for surgeons undertaking the resection of CBTs [4–6].
The introduction of newer techniques for surgical resection of CBTs holds the potential to enhance surgical outcomes for patients and streamline the surgical process for surgeons. Intracapsular dissection, a surgical method previously employed for the treatment of schwannomas, has not been widely applied to CBTs.
This study shares a single-center experience involving intracapsular dissection for Shamblin II CBTs and compare the outcomes with the classic technique of subadventitial resection (Video 1). Our surgical approach to intracapsular dissection is comprehensively detailed in a prior article [5]. This paper provides an overview of the ongoing study and presents its preliminary results.
This cohort study has been underway at Amiralam Hospital in Tehran since 2019. The study includes patients requiring surgical resection of CBTs. The inclusion criteria comprise patients with confirmed CBTs through imaging and clinical examination, those eligible for primary surgical resection, and individuals with Shamblin II tumor types. Exclusion criteria involve Shamblin I and III tumors, revision surgeries, a history of other types of neck surgery, lower cranial nerve invasion (determined by preoperative physical examination), secretory tumors (indicated by a history of blood pressure and flushing or positive VMA or metanephrine tests), and embolization prior to surgery. There are no age or gender limitations in patient selection. The patients are randomly assigned to two groups, namely subadventitial dissection as the classic surgical technique (group one) and the intracapsular dissection (enucleation) technique (group two).
As of now, over 40 patients with unilateral Shamblin II tumors have undergone surgery in two groups without any embolization. Preliminary results suggest that the enucleation technique has led to significantly lower intraoperative blood loss and shorter surgery duration compared to the subadventitial technique. There have been no reported cases of relapse, mortality, or vascular complications. However, two patients in the subadventitial group experienced hypoglossal nerve injuries, which spontaneously resolved after 6 months (Figs. 1 and 2).
Fig. 1.
The edges of tumor capsule are grabbed with forceps and the tumor nucleus is exposed. A Tumor capsule, B internal carotid arteries, C CBT
Fig. 2.
The tumor is fully separated from the attachment site at the carotid bifurcation. A Tumor capsule, B internal carotid arteries, C CBT
A recent literature report by Contrera KJ in 2020 [7] indicated a median time to recurrence of 18.4 years for head and neck paraganglioma. Consequently, it is essential to continue monitoring the patients who participated in this study and gather additional samples to expand the database, allowing for an exploration of potential disparities in the surgical outcomes of the intracapsular approach. The study results will be published upon completion of the follow-up.
Conclusion
Based on the preliminary results, it seems that the enucleation technique facilitates the dissection of carotid body tumors, offering protection to cranial nerves and the internal/external/common carotid artery by utilizing the capsule as a barrier. The classic subadventitial resection approach and the enucleation technique have shown comparable postoperative complications. However, it is crucial to continue monitoring patients who undergo these resection techniques to assess long-term outcomes. Additionally, the enucleation technique significantly reduces surgery duration and intraoperative blood loss.
Supplementary Information
Video 1: The surgical method for intracapsular dissection of carotid body tumor is available at the following links: https://youtu.be/7AIOyl6RjRk?si=UO7krjU7nXEl6nLQ and https://youtu.be/J0BJrtr4a5U?si=-igPVyUywOsJ_mMT.
Acknowledgements
None.
Funding
None.
Declarations
Ethical Approval
The research was carried out according to the principles of the declaration of Helsinki. Written consent was obtained from all patients. The ethical committee of Tehran University of Medical Sciences approved the study protocol (ID: IR.TUMS.MEDICINE.REC.1398.466).
Conflict of Interest
The authors declare no conflict of interest.
Footnotes
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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