How to do it: excision of carotid space tumours in proximity to skull base

This article along with the descriptive video demonstrates the step-by-step surgical approach for excision of tumours located in carotid space in proximity to skull base. We have described the surgical steps without mandibular osteotomy and also demonstrated the technique to safeguard all neuro-vascular anatomy in the vicinity of the carotid space and skull base. Carotid space in proximity to skull base is one of the challenging areas to access for tumour excision. Tumours like carotid body tumour, glomus tumour, nerve sheath tumour, neurofibroma, schwannoma, and lipoma are known to present at this location. Ectopic parathyroid gland has been reported in the areas from the carotid sheath to the middle mediastinum. Intra or extra-neural parathyroid adenomas adjacent to the Vagus near the skull base are exceedingly rare.1 In view of the complexity of this procedure, which involves exposing the carotid space without a mandible osteotomy, we aim to describe the stepwise technique of excision of ectopic parathyroid adenoma located in the carotid space in proximity to skull base. We also aim to describe the technique to safeguard all neuro-vascular anatomy in the vicinity of carotid space and skull base, which is useful for the excision of all tumours located in this space (Fig. 1). The carotid space is defined by the carotid sheath, which is formed by layers of the deep cervical fascia. The carotid space extends from the skull base to the aortic arch at the thoracic inlet and is divided craniocaudally into the supra and infrahyoid spaces. The suprahyoid carotid space is surrounded by the masticator and parapharyngeal spaces anteriorly, the parotid space laterally, the retropharyngeal space medially, and the prevertebral space posteriorly. The parapharyngeal fat or space will be displaced anteromedially by a mass centred within the carotid space.2 The post-styloid compartment contains neurovascular structures like Carotid artery, internal jugular vein, sympathetic chain, and cranial nerves IX, X, XI, and XII along with paraganglionic tissue.3, 4 The surgical technique of excision of ectopic parathyroid adenoma located in carotid space in proximity to the skull base is shown in Video S1. The patient was placed in supine position with the neck in extension as a standard of practice. The head was turned to the opposite side to mark an incision. A Retromandibular approach was taken 2 cm below the lower border of the mandible continuing behind the ramus. The incision was deepened through subcutaneous tissue to reach the platysma. Skin flap was raised in the subplatysmal plane and care was taken to preserve marginal mandible nerve. The digastric muscle was exposed and facial vein was divided. The submandibular gland and the posterior belly of the digastric muscle were retracted superiorly to expose the hypoglossal nerve which lies beneath and at the level of the hyoid bone. This nerve enters the digastric triangle of the neck and lies along the lateral surface of the internal (ICA) and external carotid artery (ECA). Firstly, anterior branches of ECA were encountered in the same order, lingual artery followed by the facial artery superiorly just below the hypoglossal nerve, both of which were ligated for better exposure. Medial dissection of the ECA was done to expose the only medial branch which is the Ascending Pharyngeal artery, which was ligated as well. The occipital artery, one of the posterior branch and terminal ECA was dissected from the tumour. The occipital artery was divided for better exposure. The internal carotid artery was dissected and retracted medially. The ECA and Hypoglossal nerve were retracted laterally to expose tumour in the carotid space. The superior most part of hypoglossal nerve was dissected and freed from tumour. Medial dissection was carried out after safeguarding pharyngeal and sympathetic plexus. The glossopharyngeal nerve which is located supero-medially and lateral to ICA was pushed superiorly to avoid injury. The vagus nerve was identified at the base of carotid space and meticulous dissection was performed to dissect it from the tumour. The tumour was dissected all around except superior most part, which was not visible as carotid space was occupied by tumour. Also, the mandible was obstructing the field of dissection at the superior most part. Hence, it was decided to divide the tumour to improve the vision and the superior part of tumour near skull base was excised under vision. The care was taken not to spill the tumour cells while dividing the tumour and minimal manipulation of the tumour. A thorough saline wash was given to prevent parathyromatosis.5 However, we would always recommend the intact excision of parathyroid adenoma. Haemostasis was achieved and the wound was closed in layers after placing a suction drain. The patient consent was obtained for medical videography and publication. Diksha Dinker: Conceptualization; data curation; investigation; methodology; writing – original draft; writing – review and editing. Rinsha Gireesh: Data curation; formal analysis; investigation; methodology; writing – original draft; writing – review and editing. Akhil Palod: Conceptualization; methodology; validation; writing – review and editing. Naveena A. N. Kumar: Conceptualization; data curation; formal analysis; investigation; methodology; project administration; resources; software; supervision; validation; visualization; writing – original draft; writing – review and editing. We would like to acknowledge the videography team of Kasturba Medical College, MAHE, Manipal for helping with video recording. Video S1: Excision of ectopic parathyroid adenoma located in carotid space in proximity to skull base. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.