Neuroradiology Case of the Week

Case 7

Ramon R. de Guzman, MD and P-L Westesson, MD, PhD, DDS

Diagnosis: Biopsy of Foramen Ovale Lesion

Clinical Technique: For patients with lesions to the foramen ovale, a CT-guided transfacial biopsy approach is possible. With the patient supine, the CT scanner markers are placed on the skin (Fig.1).

Figure 1: Axial CT scan showing markers on skin in preparation for a left submalar approach to avoid vital structures.

Following local anesthesia and conscious sedation, a 22-gauge needle is placed
according to the axial markers by the CT scan and the transverse markers by the skin
marks (Fig. 2).

Figure 2: Axial CT scan showing a 22-gauge needle advanced along the lateral wall of the left maxillary sinus using left submalar approach.

The needle is then gradually advanced until the tip is in the desired location (Figs.3 & 4).

Figure 3A	Figure 3B

Figure 3C

Figure 3D	Figure 3E

Figure 3A-E: Needle tip advanced along the lateral left maxillary wall into the desired location at the left foramen ovale. Several axial CT images were obtained as the needle is advanced to assure accurate needle placement.

Figure 4A	Figure 4B

Discussion: Head and neck tumors often spread by means of perineural extension. Dissemination along nerves allows tumors to gain access to noncontiguous areas, which alters the prognosis and treatment plan substantially. The mandibular division of the trigeminal nerve provides a common route for perineural metastasis. Treatment can proceed only after pathologic verification of the lesion. Obtaining histologic specimen from this area can be difficult, and an open surgical approach may be required.

CT-guided transfacial fine-needle aspiration is a simple, effective, and relatively safe method for fine-needle aspiration of lesions that involve the 3rd division of the trigeminal nerve at the level of the foramen ovale. CT guidance provides for greater accuracy in needle placement [1]. Cytology aspiration can be performed as well as core biopsies from this technique.

References:

1. Barakos JA, Dillon WP. Lesions of the Foramen Ovale: CT-Guided Fine-Needle Aspiration. Radiology 1992 Feb;182(2):573-5.