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Keywords:
Haemangioma, Diagnostic procedure, MR, CT-High Resolution, Head and neck
Authors:
C. C.-T. Hsu1, D. Singh1, K. Mclean2, M. Gandhi2; 1Brisbane, QL/AU, 2Brisbane/AU
DOI:
10.1594/ecr2016/C-0612
Aims and objectives
OBJECTIVE:
The aim of this study is to determine the reliability of preoperative CT and contrast enhanced MRI in differentiating FNS and FNVM.
INTRODUCTION:
Facial nerve schwannomas (FNSs) and facial nerve venous malformations (FNVMs) are rare lesions that arise from the facial nerve.
The clinical features,
natural history and treatment strategies for both lesions differ and therefore accurate diagnosis at imaging is crucial to assist the otorhinolaryngologist in management and operative planning.
FNSs are slow-growing lesions that can present with hearing loss,
tinnitus,
vertigo and over half of patients present with facial nerve (FN) paralysis [1,2].
The major management goal for FNSs is preservation of FN function for the longest duration possible [1].
An initial trial of non-operative management with imaging surveillance may be used,
especially for patients with lower House-Brackmann grade lesions (I - III).
Surgical treatment is reserved for cases with worsening symptoms or in large tumors.
Surgical options include FN decompression,
tumor debulking and resection with FN grafting [1,2].
FNVMs,
formerly known as facial nerve hemangiomas,
are a type of venous malformation that originate from the rich capillary plexus surrounding the genicualte ganglion of the FN.
Histologically,
FNVMs show dilated and tortuous vessels,
with absence of normal internal elastic lamina and only scant smooth muscle [3-5].
Symptoms of FNVMs include FN palsy,
hemifacial spasm,
hearing loss and vertigo [3].
The presenting FN palsy maybe acute in some instances.
Symptomatic FNVMs maybe due to local extra-neural compression or direct neural infiltration.
FNVMs can also also involve the cochlear and vestibular complexes causing hearing loss and vertigo [3].
Although both FNVMs and FNSs are slow-growing the clinical deficits with FNVMs are often out of proportion to the size of lesion.
Thus,
early diagnosis is crucial to preserve FN function and avoid the dreaded complication of conductive or sensorineural hearing loss.
High resolution CT (HRCT) of the temporal bone in conjunction with MRI may assist in differentiation between these two pathologies.