Trigeminal neuralgia secondary to basilar impression: A case report

Abstract

We report a rare case of trigeminal neuralgia. A 23-year-old woman with a history of 1 year of typical trigeminal neuralgia manifested the characteristics of basilar impression. Magnetic resonance imaging (MRI) demonstrated basilar impression, deformity of the posterior fossa with asymmetry of petrous bone, and compression of medulla oblongata in the topography of the odontoid apophysis. The operation was performed through a suboccipital craniectomy. The neuralgia disappeared after surgery and remains completely resolved until today. This is the second reported case of trigeminal neuralgia in a patient with basilar impression in Brazil.

A Case of Trigeminal Neuralgia in an Adult Patient With Lambdoid Synostosis

“…The most common cause of TN is compression of the fifth cranial nerve at its REZ by a vascular loop [ 1 ]. Although the role of anatomical structures in the pathogenesis of TN has not been well understood, previous studies suggested a relationship between susceptibility to TN and canonical structural anomalies, such as cases of TN associated with posterior cranial deformities [ 6 , 7 ], among which Smartt et al reported that the petrous ridge angle was larger in the lambdoid synostosis group on the unaffected side [ 8 ]. In the present case, the following anatomical parameters were observed: the length of the TGN was shorter on the unaffected side (8.1 mm vs. 9.2 mm); the calculated area of the cistern was narrower (170.2 mm 2 vs. 198.0 mm 2 ) on the unaffected side at the level of the fifth cranial nerve; and the angle between the ventral median line and the petrous ridge (petrous ridge angle) was larger on the unaffected side (131° vs. 122°), although deviation of the median line of the patient’s skull impeded correct assessment of the actual petrous angle.…”

“…In fact, there are scattered reports of NVC-related TN in adult patients associated with diseases involving posterior cranial deformities [ 6 , 7 ]. Based on these considerations, mild lambdoid synostosis cases, especially adults who were asymptomatic in childhood, may experience more frequent TN due to NVC associated with deformities of the posterior cranial fossa.…”

Small Posterior Cranial Fossa and Cerebellopontine Cistern Volumes Are Associated With Bilateral Trigeminal Neuralgia

“…Currently, the theory of peripheral lesions has been accepted by most scholars (13). Regarding the pathogenesis of TN, it is believed that the trigeminal nerve becomes chronically compressed by abnormal twisted microvessels in the REZ area, resulting in inflammation and demyelination changes in the root of the trigeminal nerve and thus in a "short circuit" of membrane potential and neuropathic pain in the trigeminal nerve distribution area (14). One study (4) showed that the size, shape, and structure of the skull varies according to race and sex.…”

“…The space occupied by tissues of the posterior fossa is small, resulting in NVC of the trigeminal nerve and clinical symptoms. However, for people with a large posterior fossa volume, there will be no symptoms of compression, clinical pain or other discomfort, even if the blood vessels are in contact with the nerve ( 15 ). In our study, the mean VPCF in the UTN group was significantly lower than that in the healthy control group ( p < 0.05).…”

Case report of unusual cause of trigeminal neuralgia: Trigeminal neuralgia secondary to enlarged suprameatal tubercle

“…Bony abnormalities, as petrous bone deformities or basilar impression, causing compression over trigeminal nerve or nucleus have been reported previously [ [8] , [9] , [10] ]. However, EST as a cause of TN has not been reported yet.…”