Trigeminal neuralgia (TN) is a debilitating neurological disease that commonly results from neurovascular compression of the trigeminal nerve (CN V). Although the CN V has been extensively studied at the site of neurovascular compression, many pathophysiological factors remain obscure. For example, thalamic-somatosensory function is thought to be altered in TN, but the abnormalities are inadequately characterized. Furthermore, there are few studies using 7-T MRI to examine patients with TN. The purpose of the present study was to use 7-T MRI to assess microstructural alteration in the thalamic-somatosensory tracts of patients with TN by using ultra–high field MRI.
Ten patients with TN and 10 age- and sex-matched healthy controls underwent scanning using 7-T MRI with diffusion tensor imaging. Structural images were segmented with an automated algorithm to obtain thalamus and primary somatosensory cortex (S1). Probabilistic tractography was performed between the thalamus and S1, and the microstructure of the thalamic-somatosensory tracts was compared between patients with TN and controls.
Fractional anisotropy of the thalamic-somatosensory tract ipsilateral to the site of neurovascular compression was reduced in patients (mean 0.43) compared with side-matched controls (mean 0.47, p = 0.01). The mean diffusivity was increased ipsilaterally in patients (mean 6.58 × 10−4 mm2/second) compared with controls (mean 6.15 × 10−4 mm2/second, p = 0.02). Radial diffusivity was increased ipsilaterally in patients (mean 4.91 × 10−4 mm2/second) compared with controls (mean 4.44 × 10−4 mm2/second, p = 0.01). Topographical analysis revealed fractional anisotropy reduction and diffusivity elevation along the entire anatomical S1 arc in patients with TN.
The present study is the first to examine microstructural properties of the thalamic-somatosensory anatomy in patients with TN and to evaluate quantitative differences compared with healthy controls. The finding of reduced integrity of these white matter fibers provides evidence of microstructural alteration at the level of the thalamus and S1, and furthers the understanding of TN neurobiology.
ABBREVIATIONSAD = axial diffusivity; CN V = trigeminal nerve; DTI = diffusion tensor imaging; FA = fractional anisotropy; MD = mean diffusivity; MP2RAGE = magnetization-prepared 2 rapid acquisition gradient echoes; RD = radial diffusivity; REZ = root entry zone; ROI = region of interest; S1 = primary somatosensory cortex; TN = trigeminal neuralgia.
Correspondence John W. Rutland: Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY. firstname.lastname@example.org.
INCLUDE WHEN CITING Published online August 30, 2019; DOI: 10.3171/2019.6.JNS19541.
Disclosures Dr. Balchandani, the principal investigator in this study, is a named inventor on patents relating to MRI and radiofrequency (RF) pulse design. The patents have been licensed to GE Healthcare, Siemens AG, and Philips International. Dr. Balchandani receives royalty payments relating to these patents. Dr. Balchandani is a named inventor on patents relating to Slice-selective adiabatic magnetization T2-preparation (SAMPA) for efficient T2-weighted imaging at ultra–high field strengths, Methods for Producing a Semi-Adiabatic Spectral-Spatial Spectroscopic Imaging Sequence and Devices Thereof, and Semi-Adiabatic Spectral-Spatial Spectroscopic Imaging. Dr. Bederson, a significant contributor in this study and chair of the Department of Neurosurgery, owns equity in Surgical Theater, LLC (manufacturer of the Surgical Navigation Advanced Platform [SNAP] system that may have been used for intraoperative image guidance in the study).
AntalA, TerneyD, KühnlS, PaulusW: Anodal transcranial direct current stimulation of the motor cortex ameliorates chronic pain and reduces short intracortical inhibition. 39:890–903, 20102047154910.1016/j.jpainsymman.2009.09.023)| false
HughesMA, FredericksonAM, BranstetterBF, ZhuX, SekulaRFJr: MRI of the trigeminal nerve in patients with trigeminal neuralgia secondary to vascular compression. 206:595–600, 20162690101710.2214/AJR.14.14156)| false
KolodziejMAHellwigDNimskyCBenesL: Treatment of central deafferentation and trigeminal neuropathic pain by motor cortex stimulation: report of a series of 20 patients. J Neurol Surg A Cent Eur Neurosurg77:52–582016
KolodziejMA, HellwigD, NimskyC, BenesL: Treatment of central deafferentation and trigeminal neuropathic pain by motor cortex stimulation: report of a series of 20 patients. 77:52–58, 201626351869)| false
LutzJThonNStahlRLummelNTonnJCLinnJ: Microstructural alterations in trigeminal neuralgia determined by diffusion tensor imaging are independent of symptom duration, severity, and type of neurovascular conflict. J Neurosurg124:823–8302016
LutzJ, ThonN, StahlR, LummelN, TonnJC, LinnJ, : Microstructural alterations in trigeminal neuralgia determined by diffusion tensor imaging are independent of symptom duration, severity, and type of neurovascular conflict. 124:823–830, 20162640679210.3171/2015.2.JNS142587)| false
MetwalliNS, BenatarM, NairG, UsherS, HuX, CarewJD: Utility of axial and radial diffusivity from diffusion tensor MRI as markers of neurodegeneration in amyotrophic lateral sclerosis. 1348:156–164, 201010.1016/j.brainres.2010.05.06720513367)| false
RutlandJWPadormoFYimCKYaoAArrighi-AllisanAHuangKH: Quantitative assessment of secondary white matter injury in the visual pathway by pituitary adenomas: a multimodal study at 7-Tesla MRI. J Neurosurg [epub ahead of print January182019. DOI: 10.3171/2018.9.JNS182022]
RutlandJW, PadormoF, YimCK, YaoA, Arrighi-AllisanA, HuangKH, : Quantitative assessment of secondary white matter injury in the visual pathway by pituitary adenomas: a multimodal study at 7-Tesla MRI. 18, 2019. DOI: 10.3171/2018.9.JNS182022])| false
SatoK, NariaiT, SasakiS, YazawaI, MochidaH, MiyakawaN, : Intraoperative intrinsic optical imaging of neuronal activity from subdivisions of the human primary somatosensory cortex. 12:269–280, 20021183960110.1093/cercor/12.3.269)| false
WinklewskiPJ, SabiszA, NaumczykP, JodzioK, SzurowskaE, SzarmachA: Understanding the physiopathology behind axial and radial diffusivity changes—what do we know?9:92, 201810.3389/fneur.2018.0009229535676)| false