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Perineural tumor extension through the foramen ovale: evaluation with MR imaging
F J Laine1, I F Braun, M E Jensen
1Department of Radiology, Medical College of Virginia, Richmond 23298-0615.
Abstract:
Perineural tumor extension is a form of metastatic disease in which primary tumors spread along neural pathways and gain access to non-contiguous regions. The treatment and prognosis are altered when perineural extension occurs. Awareness and proper evaluation are critical for the radiologist. The third (mandibular) division of the trigeminal nerve (V3), passing through the skull base via the foramen ovale, is a common route of perineural spread of head and neck lesions. Seven patients with perineural tumor involvement of the mandibular nerve were evaluated with magnetic resonance imaging with use of standard spin-echo pulse sequences emphasizing T1-weighted information. Three patients had adenoid cystic carcinoma, three had squamous cell carcinoma, and one had well-differentiated lymphocytic lymphoma of the orbit. MR imaging signs of perineural involvement included smooth thickening of V3, concentric expansion of the foramen ovale, replacement of the normal trigeminal cistern hypointensity by an isointense mass, lateral bulging of cavernous sinus dural membranes, and atrophy of masticator muscles.
Insights
Perineural tumor spread along the mandibular nerve (V3) impacts head and neck cancer treatment. Magnetic resonance imaging (MRI) reveals key signs like nerve thickening and foramen ovale changes.
Area of Science:
- Radiology
- Oncology
- Neurology
Background:
- Perineural tumor extension involves cancer spreading via neural pathways, altering prognosis and treatment.
- The mandibular nerve (V3) is a frequent pathway for head and neck cancers to spread through the skull base.
- Radiological awareness is crucial for diagnosing perineural spread.
Purpose of the Study:
- To evaluate magnetic resonance imaging (MRI) findings in patients with perineural tumor involvement of the mandibular nerve (V3).
- To identify characteristic MRI signs indicative of V3 perineural spread.
Main Methods:
- Retrospective analysis of seven patients with confirmed perineural tumor involvement of V3.
- Utilized standard spin-echo MRI sequences with T1-weighted imaging.
- Correlated imaging findings with histopathological diagnoses.
Main Results:
- MRI revealed specific signs of perineural involvement: smooth V3 thickening, concentric foramen ovale expansion, trigeminal cistern mass, cavernous sinus dural bulging, and masticator muscle atrophy.
- Diagnoses included adenoid cystic carcinoma, squamous cell carcinoma, and orbital lymphoma.
- Demonstrated the utility of MRI in detecting V3 perineural spread.
Conclusions:
- MRI is effective in identifying perineural tumor spread along the mandibular nerve (V3).
- Recognizing specific MRI features aids in accurate diagnosis and management of head and neck cancers with perineural invasion.
- Early detection through MRI can influence patient treatment and outcomes.