Trigeminal neuropathy after tooth extraction
An elderly woman presented with severe right facial pain after a recent upper molar tooth extraction.
Brain and cerebellopontine angle
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Thin axial T2-weighted images of the cranial nerve V course shows no evidence for vascular compression or mass lesion, particularly on the right side.
Upon contrast administration, avid enhancement of the intracranial right trigeminal nerve from its origin at the pons, at its cisternal segment, to the trigeminal ganglion and likely at the cavernous sinus is appreciated.
There is also abnormal enhancement of the meninges along the right Meckel's cave. The left trigeminal nerve course shows no abnormal signal change or enhancement.
2 case question available
Peripheral trigeminal nerve injury as a consequence of dental surgery has been reported to range from 1 to 4 out of 1000 molar extractions. The most frequently injured nerves are the inferior alveolar (60%), followed by the lingual nerve. The imaging of post-surgical trigeminal neuropathy is not routinely performed and has not been described in the literature, as this is most often a clinical diagnosis.
The role of the radiologist is to understand the normal anatomy and enhancement pattern of the trigeminal nerve as to be able to discern any abnormal findings. The CN V intracranial portions include its brainstem nuclei, prepontine cistern, Meckel's cave and cavernous sinus segments. The extracranial segments are formed by V1, V2, and V3 which merge at the posterior cavernous sinus to form the trigeminal ganglion. An extensive perineural venous plexus obscures and gives the appearance of an enhancing trigeminal ganglion.
On the other hand, true neuritis could produce isolated or unilateral nerve enhancement on all MR planes. The most common intracranial causes can be discerned based on the location of abnormality (e.g. multiple sclerosis for brainstem, neurovascular compression at the cisterns, or tumors at the Meckel's cave and cavernous sinus).
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