Nerve atrophy and a small cerebellopontine angle cistern in patients with trigeminal neuralgia

Abstract

Among the patients with TN, there was a statistically significant difference in the MR imaging findings of the affected side compared with the unaffected side of the trigeminal nerve. Atrophy of the trigeminal nerve and a small CPA cistern in patients with TN provides additional markers for the diagnosis of TN and helps confirm the diagnosis based on clinical examination.

Degree of distal trigeminal nerve atrophy predicts outcome after microvascular decompression for Type 1a trigeminal neuralgia

“…viduals. 4,5,7,9,10,17 In a retrospective study of 30 patients with idiopathic TN, Ha and colleagues demonstrated that, on preoperative FIESTA MRI, there was significantly more atrophy at the cisternal segment of the trigeminal nerve on the affected side than on the unaffected side compared with the affected and unaffected sides of age-and sexmatched control patients with hemifacial spasm. 5 Of note, these authors also found a significant association between the sharpness of the trigeminal-pontine angle on the affected side compared with the unaffected side, which was not found in the control group.…”

“…Numerous studies have assessed the pattern of neurovascular conflict (NVC) due to crowding of the cisternal space and the neurovascular structures that occupy that space and its association with symptoms of TN. 5,7,17,18 Park and colleagues retrospectively reviewed MRI studies of 26 patients with unilateral TN treated with Gamma Knife radiosurgery. 17 They found a significantly smaller crosssectional area in the cerebellar-pontine angle cistern in the symptomatic side compared with the asymptomatic side, as well as a shorter cisternal segment of the trigeminal nerve on the affected side.…”

“…5,7,17,18 Park and colleagues retrospectively reviewed MRI studies of 26 patients with unilateral TN treated with Gamma Knife radiosurgery. 17 They found a significantly smaller crosssectional area in the cerebellar-pontine angle cistern in the symptomatic side compared with the asymptomatic side, as well as a shorter cisternal segment of the trigeminal nerve on the affected side. Both of these findings were felt to contribute to an increased opportunity for NVC, manifesting in symptoms of TN.…”

“…8,10,13,21 Structural changes in the trigeminal nerve, leading to volume loss, have been well documented, 3,6,12 and a number of studies have demonstrated that nerve atrophy ipsilateral to the symptomatic side is visible on preoperative MRI. 1,4,5,7,9,15,17 Recently, Leal et al demonstrated that atrophy in the midcisternal region of the nerve is associated with more severe vascular compression, and these patients tend to exhibit greater clinical improvement following surgical decompression of the nerve. 10 However, it is unclear whether the nerve atrophy is entirely due to physical compaction by the compressing vessel or whether it is due, in part, to irreversible structural changes.…”

Usefulness of the endoscope in microvascular decompression for trigeminal neuralgia and MRI-based prediction of the need for endoscopy

“…However, there was a strong, statistically significant correlation between the fraction of visible trigeminal nerve (FVN) on preoperative MRI and the occurrence of a troublesome bony ridge during surgery (p<0.001) In our view, the fraction of visible trigeminal nerve describes the combination of differences in the width of the CPA cistern and the occurrence of a bony ridge of various degrees. The width of the CPA varies and is known to be narrower in patients affected with TN [20,21]. When a patient with a congenital or otherwise acquired (descending tentorium with age [21]) narrow CPA additionallyhas a bony ridge (although small, relatively speaking), the combination of the two causes problems for the surgeon.…”