Efficacy of microvascular decompression in patients with trigeminal neuralgia with negative neurovascular relationship shown by magnetic resonance tomography.

OBJECTIVE: To explore the surgical efficacy of microvascular decompression(MVD) when the recent magnetic resonance tomography angiography(MRA) is unable to determine the relationship between blood vessels and nerves in patients with trigeminal neuralgia(TN).

MATERIALS AND METHODS: The MRI images of 146 patients with TN who underwent MVD from January 2016 to December 2019 were analyzed retrospectively. The relationship between nerves and vessels was categorized as no contact, suspicious contact, and clear contact. Suspicious contact and clear contact were both defined as positive neurovascular relationship, whereas no contact was defined as negative neurovascular relationship. The efficacy of MVD in positive and negative groups was compared.

RESULTS: 1. A total of 146 TN patients underwent MVD. Intraoperative examination revealed that out of 146, 143 patients exhibited contacts, including 110 cases with arterial contact, 22 cases with combined arterial and venous contact, and 11 cases with venous contact. Considering the surgical result as a gold standard, the sensitivity of three-dimensional time leap angiography (3D-TOF-MRA) in assessing vascular compression in TN was 74.0 %; and the sensitivity of three-dimensional steady-state precession rapid imaging sequence (3D-FIESTA) in determining vascular compression was 82.2 %. Out of a total of 17 cases demonstrating negative neurovascular relationship by 3D-TOF-MRA together with 3D-FIESTA, 14 cases were found to have vascular contact during the surgery, and the sensitivity was determined to be 88.4 %. 2.Among the 38 patients with a negative neurovascular relationship demonstrated by 3D-TOF, postoperative efficacy was noted as a cure: 30 cases, improved: 5 cases, no effect: 3 cases. 3D-FIESTA showed 26 cases of negative neurovascular relationship, among them, cured: 20 cases, improved: 3 cases, no effect: 3 cases. A total of 17 patients with negative neurovascular relationships were established by 3D-TOF-MRA together with 3D-FIESTA, and the postoperative effects were found to be cure: 13 cases, improvement: 2 cases, and no effect: 2 cases. There was no statistically significant difference between the negative group and the positive group (x2 test; p > 0.05).

CONCLUSION: To conclude, 3D-TOF-MRA, together with 3D-FIESTA, can illustrate the large blood vessels surrounding the trigeminal nerve efficiently, and determine whether it is the offending blood vessel. The interpretation would help reproduce the local anatomical spatial structure of the site before surgery, yet it is impossible to assess the peripheral anatomical relationship of the trigeminal nerve cistern comprehensively and accurately. This hints that a perfect prediction of the surgical effect of MVD is not possible at present. Thus, typical symptoms of TN are the most critical indicators for MVD surgery.