Anatomical Study of the Internal Maxillary Artery at the Pterygomaxillary Fissure

Objective: To evaluate and better describe the anatomy of the internal maxillary artery (IMAX) at the pterygomaxillary fissure and confirm the feasibility of IMAX ligation via a sublabial endoscopic approach.

Background: Control of posterior epistaxis is well described in the literature, including transnasal endoscopic sphenopalatine artery ligation (TESPAL) and arterial embolization of the IMAX, both with extremely high success rates. Despite this abundant literature, anatomy of the IMAX at its transition to the sphenopalatine artery is limitedly described. Given the greater cost efficacy of surgical control of epistaxis compared with embolization, ligation of the IMAX may be an alternative option. For patients with severe nasal bleeding who cannot tolerate further blood loss encountered via an endonasal approach, the permanence of nasal packing is desirable and feasible with IMAX ligation. With the advances of endoscope technology this may be a suitable option with improved knowledge of the IMAX anatomy.

Study Design: Cadaveric anatomic study.

Methods: Ten cadaveric specimens were injected with red silicone into the common carotid arteries. Sublabial approach was performed and the left IMAX was dissected and measurements of artery location determined as it entered the pterygomaxillary fissure (PMF) with reference to the inferior zygomaticomaxillary suture (ZMMS) and base of the pterygoid hammulus. Endoscopic ligation of the contralateral IMAX was performed via a sublabial approach on a subset of the specimens, which was then reconfirmed via a transnasal endoscopic sphenopalatine artery ligation (TESPAL) approach.

Results: Using bony landmarks, the IMAX was found to be in a readily identifiable location within the pterygomaxillary fissure. The IMAX was a mean distance of 2.85cm (SD 0.42cm) from the inferior ZMMS and mean of 2.8cm (SD 0.58cm) from the base of the pterygoid hammulus. IMAX ligation was performed endoscopically via a sublabial approach. Dissection after staple placement confirmed ligation of the IMAX as it entered the PMF. Identification of the ligated IMAX proximal to its transition to the SPA was confirmed via TESPAL.

Conclusion: The IMAX is readily identifiable using the ZMMS and pterygoid hammulus as bony landmarks. Cadaveric models confirm the feasibility of IMAX ligation via an endoscopic sublabial approach, which may be a suitable alternative for control of intractable epistaxis, particularly for patients whom the permanence of nasal packing is desirable during the procedure.