Facial nerve hemangioma.

Bell's palsy accounts for almost 50% of all cases of facial nerve paralysis. (1) Tumors are involved in only 5% of cases of facial paralysis, and the most common tumors are acoustic and facial neuromas. (2) Facial nerve hemangiomas account for only 0.7% of all temporal bone tumors. (1-3) Facial nerve hemangiomas arise from vascular plexuses distributed along the facial nerve paths in the geniculate ganglion region, in the mastoid segment of the facial nerve near the origin of the chorda tympani, and in the internal auditory canal around Scarpa's ganglion. (2)

Microscopically, facial nerve hemangiomas are seen as large vascular spaces lined with thin endothelium surrounded by thick walls filled with uniform fibrous tissue. (1,2) The characteristic honeycomb appearance seen on computed tomography (CT) (figure, A) is the result of erosion of the temporal bone and calcification of the collagen-containing walls between the vascular channels. The presence of bony channels, indistinct tumor margins, and intratumor bony spicules led to the term ossifying hemangiomas. (3)

[FIGURE A OMITTED]

High-resolution CT and enhanced magnetic resonance imaging (MRI) (figure, B) together are the most sensitive diagnostic modalities available to demonstrate facial nerve hemangiomas. (1)

[FIGURE B OMITTED]

Facial nerve hemangiomas and facial nerve neuromas yield similar clinical findings. Characteristically, severe nerve dysfunction is seen in patients with small hemangiomas; tinnitus and dizziness are seldom present. Conversely, symptomatic facial nerve neuromas are relatively large. Facial nerve hemangiomas and neuromas can be differentiated by their histologic appearance and by the presence or absence of the ossifying characteristics of facial nerve hemangiomas. (2) Facial nerve hemangiomas should also be distinguished from meningiomas, congenital cholesteatomas, metastatic carcinomas, and other vascular tumors that involve the temporal bone.

Surgical removal is the definitive treatment. In view of the extrinsic growth pattern of these tumors, surgical removal should be performed early to preserve facial nerve function. (4) Tumors in the geniculate ganglion region usually lead to an intense perineural reaction or direct nerve infiltration. Therefore, the opportunities to preserve an intact nerve following surgery are limited. Treatment by total excision and facial nerve grafting can provide a permanent cure and restore facial function. (2,5)

References

(1.) Salib RJ, Tziambazis E, McDermott AL. et al. The crucial role of imaging in detection of facial nerve haemangiomas. J Laryngol Otol 2001;115:510-13.

(2.) Escada P, Capucho C, Silva JM, el al. Cavernous haemangioma of the facial nerve. J Laryngol Otol 1997:111:858-61.

(3.) Friedman O. Neff BA, Willcox TO, et al. Temporal bone hemangiomas involving the facial nerve. Otol Neurotol 2002;23:760-6.

(4.) Alobid I, Gaston F, Morello A, et al. Cavernous haemangioma of the internal auditory canal. Acta Otolaryngol 2002:122:501-3.

(5.) Pulec JL. Facial nerve angioma. Ear Nose Throat J 1996:75: 225-38.