Arterial Supply of Glomus Tympanicum
Glomus tympanicum tumors are almost universally supplied by branches of the ascending pharyngeal artery, specifically from the inferior tympanic artery branch. 1
Primary Arterial Supply
The inferior tympanic artery, a branch of the ascending pharyngeal artery, is the dominant blood supply to glomus tympanicum tumors. 1, 2
The ascending pharyngeal artery consistently provides the main vascular supply because glomus tympanicum tumors arise from neuroendocrine paraganglion cells of the tympanic plexus (Jacobson's nerve) on the medial wall of the middle ear. 3
Additional Contributing Vessels
Tumors may receive supplementary blood supply from clival branches of the internal carotid artery when the tumor extends around or involves the carotid canal. 1
The stylomastoid branch of the posterior auricular artery can contribute to the vascular supply, particularly when there is mastoid extension. 2
Multiple branches from both the external and internal carotid systems may contribute depending on tumor extent and location within the temporal bone. 2
Clinical Implications for Angiographic Evaluation
Selective catheterization of both external and internal carotid branches is required during angiography to adequately delineate the complete blood supply. 1
Superselective catheterization of external carotid branches confirms the blood supply and may reveal dangerous intracranial anastomoses that must be identified before any embolization procedure. 1
Evaluation of the contralateral carotid branches should be performed to exclude contribution to tumor blush, particularly when the tumor has crossed the midline. 1
Anatomic Distinction from Glomus Jugulare
Unlike glomus jugulare tumors which arise in the jugular fossa and may have more complex vascular supply from vertebral artery branches, glomus tympanicum tumors confined to the middle ear have more predictable arterial anatomy centered on the ascending pharyngeal system. 1, 2
A transcanalicular angiographic view can separate the middle ear from the jugular fossa, allowing better visualization and assessment of tumor blush to distinguish glomus tympanicum from glomus jugulare. 2
Preoperative Vascular Mapping
Digital subtraction angiography allows identification of displaced feeders to the tumor, facilitating their localization and potential ligation during surgery. 1
Angiographic mapping correlates well with surgical findings in defining tumor involvement within the middle ear, though high-resolution CT remains the first-line imaging modality for diagnosis. 3, 2