Diffusion tensor imaging for assessment of microstructural changes associate with treatment outcome at one-year after radiofrequency Rhizotomy in trigeminal neuralgia

Shu-Tian Chen,Hsu-Huei Weng,Yuan-Hsiung Tsai,Hsueh-Lin Wang,Mei-Yu Yeh,Jen-Tsung Yang

doi:10.1186/s12883-019-1295-5

Shu-Tian Chen, Hsu-Huei Weng + Show 4 more

Open Access

https://doi.org/10.1186/s12883-019-1295-5

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Abstract

BackgroundTrigeminal neuralgia (TN) is characterized by facial pain that may be sudden, intense, and recurrent. Neurosurgical interventions, such as radiofrequency rhizotomy, can relieve TN pain, but their mechanisms and effects are unknown. The aim of the present study was to investigate the microstructural tissue changes of the trigeminal nerve (TGN) in patients with TN after they underwent radiofrequency rhizotomy.MethodsThirty-seven patients with TN were recruited, and diffusion tensor imaging was obtained before and two weeks after radiofrequency rhizotomy. By manually selecting the cisternal segment of the TGN, we measured the volume of the TGN, fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD). The TGN volume and mean value of the DTI metrics of the post-rhizotomy lesion side were compared with those of the normal side and those of the pre-rhizotomy lesion side, and they were correlated to the post-rhizotomy visual analogue scale (VAS) pain scores after a one-year follow-up.ResultsThe alterations before and after rhizotomy showed a significantly increased TGN volume and FA, and a decreased ADC, AD, and RD. The post-rhizotomy lesion side showed a significantly decreased TGN volume, FA, and AD compared with the normal side; however, no significant difference in the ADC and RD were found between the groups. The TGN volume was significantly higher in the non-responders than in the responders (P = 0.016).ConclusionOur results may reflect that the effects of radiofrequency rhizotomy in TN patients include axonal damage with perineural edema and that prolonged swelling associated with recurrence might be predicted by MRI images. Further studies are necessary to understand how DTI metrics can quantitatively represent the pathophysiology of TN and to examine the application of DTI in the treatment of TN.

Highlights

Trigeminal neuralgia (TN) is characterized by facial pain that may be sudden, intense, and recurrent
We demonstrated that patients with trigeminal neuralgia who received radiofrequency rhizotomy may have had axonal injury with perineural edema at the cisternal segment of the trigeminal nerve (TGN) after the intervention
These microstructural abnormalities are characterized by a higher fractional anisotropy (FA) and lower apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) in the post-rhizotomy lesion side compared with the pre-rhizotomy lesion side and by a decreased FA and AD compared with the normal side

Summary

Introduction

Trigeminal neuralgia (TN) is characterized by facial pain that may be sudden, intense, and recurrent. Neurosurgical interventions, such as radiofrequency rhizotomy, can relieve TN pain, but their mechanisms and effects are unknown. The aim of the present study was to investigate the microstructural tissue changes of the trigeminal nerve (TGN) in patients with TN after they underwent radiofrequency rhizotomy. Trigeminal neuralgia (TN) is a common cause of facial pain and is characterized by a recurrent sudden onset of electric shock-like pain that is localized to the sensory supply area of the trigeminal nerve (TGN). Among the various interventional pain therapies, radiofrequency rhizotomy provides the highest initial pain free experience; 15–20% of patients experience recurrent TN within 12 months [15]

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