Elsevier

Surgical Neurology

Volume 59, Issue 2, February 2003, Pages 93-99
Surgical Neurology

Endovascular
Demonstration of neurovascular compression in trigeminal neuralgia and hemifacial spasm with magnetic resonance imaging: Comparison with surgical findings in 60 consecutive cases

https://doi.org/10.1016/S0090-3019(02)00993-XGet rights and content

Abstract

Background

Until recently, it has been impossible to demonstrate vascular compression at the root entry or exit zone (REZ) of the trigeminal nerve and facial nerve in patients with trigeminal neuralgia (TN) and hemifacial spasm (HFS) preoperatively, although surgical findings have revealed apparent neurovascular compression and its correction has resulted in a good outcome in most cases. Revealing the anatomic correlation between nerves and vessels at the REZ preoperatively would be useful to predict operative findings.

Methods

To assess whether the vascular contact of the nerve at the REZ could be demonstrated preoperatively, high-resolution magnetic resonance tomographic angiography (MRTA) was performed in 21 patients with TN and 39 with HFS. Neuroradiological findings were compared with the operative findings in all patients. Contralateral asymptomatic nerves were evaluated as a control.

Results

MRTA correctly identified offending vessels in 14 (67%) of the 21 TN and 34 (87%) of the 39 HFS patients. Failure to identify neurovascular contact was noted in the cases with compression by veins or small arteries, thickened arachnoid, or distal compression. Neurovascular contact was also observed in 15% of the asymptomatic nerves. The deformity of the nerve seemed to be a more important factor for determining operative indication.

Conclusions

MRTA could demonstrate offending vessels in TN and HFS at a high rate and was useful to predict operative findings. MRTA gave supportive evidence of surgical indications in patients with TN and HFS, although attention should be paid to the fact that MRTA did not necessarily detect all of the offending vessels.

Section snippets

Magnetic resonance tomographic angiography

All patients underwent MRTA preoperatively using a 1.5-Tesla MR scanner (Philips Gyroscan ACS-NT Power Truk 1000 Advanced) to evaluate the neurovascular relationship as a routine examination. Scanning parameters were repetition time (TR) of 24 msec, echo time (TE) of 4.9 msec, and flip angle of 22°. This technique generates slices of 0.9-mm thickness and 0.45-mm slice gap (over contiguous slices). It displays vessels as hyperintense structures, cerebrospinal fluid (CSF) as hypointense, and

Offending vessels on MRTA

Excluding the cases of motion artifact, satisfactory images were obtained in all 60 cases and evaluated. In the cases of TN, neurovascular contact at the REZ was revealed in 15 (71%) of the 21 symptomatic cases. On MRTA, the single superior cerebellar artery (SCA) alone was responsible in 13 cases (Figure 1A). A duplicated SCA and anterior inferior cerebellar artery (AICA) were seen to compress the trigeminal nerve in the other 2 cases. Vessels in contact with the nerves were not found on MRTA

Discussion

Recently, it has been accepted that the cause of TN or HFS is neurovascular compression at the REZ and surgical decompression results in good relief from the symptoms. Vascular compression was noted at operation in about 80 to 90% of cases 9, 16, 30. Until now, it has been difficult to determine neurovascular relationships preoperatively on CT, conventional MRI, or cerebral angiography. The fact that neurovascular compression is not recognized until the operation raises the question of whether

Conclusions

In TN and HFS cases, MRTA could reveal a neurovascular relationship and be useful for operative planning. Although operative indications should be based on clinical symptoms, vascular contact at the REZ on the symptomatic side provides support for operation. The combination of neurovascular compression and deformity of the affected nerve is a more convincing finding. There is a possibility that improper operative indications could be applied especially in cases of atypical symptoms, when

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