Fractional anisotropy of the optic radiations correlates with the visual field after epilepsy surgery
This study assessed whether optic radiations (OR) microstructure after temporal lobe epilepsy (TLE) surgery correlated with visual field defects (VFD).
Patients were subjected to diffusion tensor imaging (DTI) tractography of the OR and Humphrey perimetry after TLE surgery. We used Spearman’s test to verify correlations between tractographic parameters and perimetry mean deviation. Tractographic variables were compared between patients with VFD or intact perimetry. Multiple logistic regression was applied between DTI and perimetry values. DTI sensitivity and specificity were assessed with a receiver operating characteristic (ROC) curve to evaluate VFD.
Thirty-nine patients had reliable perimetry and OR tractography. There was a significant correlation between (1) fractional anisotropy (FA) and both total (rho = 0.569, p = 0.0002) and quadrant (rho = 0.453, p = 0.0037) mean deviation and (2) radial diffusivity and total mean deviation (rho = − 0.350, p = 0.0286). There was no other significant correlation. Patients with VFD showed a significantly lower FA compared with patients with normal perimetry (p = 0.0055), and a 0.01 reduction in FA was associated with a 44% increase in presenting VFD after surgery (confidence interval, CI = 1.10–1.88; p = 0.0082). Using a FA of 0.457, DTI tractography showed a specificity of 95.2% and a sensitivity of 50% to detect VFD after surgery (area under the curve = 0.7619, CI = 0.6020–0.9218).
The postoperative OR microstructure correlated with visual loss after epilepsy surgery. DTI postoperative OR tractography may be helpful in evaluating VFD.
KeywordsPerimetry Visual field defect Optic radiations Epilepsy surgery Tractography
This work was funded by the São Paulo Research Foundation (FAPESP).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
- 6.Yogarajah M, Focke NK, Bonelli S, Cercignani M, Acheson J, Parker GJM, Alexander DC, McEvoy AW, Symms MR, Koepp MJ, Duncan JS (2009) Defining Meyer’s loop-temporal lobe resections, visual field deficits and diffusion tensor tractography. Brain 132:1656–1668. https://doi.org/10.1093/brain/awp114 CrossRefGoogle Scholar
- 8.Yeni SN, Tanriover N, Uyanik Ö, Ulu MO, Özkara Ç, Karaağaç N, Ozyurt E, Uzan M (2008) Visual field defects in selective amygdalohippocampectomy for hippocampal sclerosis: the fate of Meyer’s loop during the Transsylvian approach to the temporal horn. Neurosurgery 63:507–515. https://doi.org/10.1227/01.NEU.0000324895.19708.68 CrossRefGoogle Scholar
- 9.Winston GP, Mancini L, Stretton J, Ashmore J, Symms MR, Duncan JS, Yousry TA (2011) Diffusion tensor imaging tractography of the optic radiation for epilepsy surgical planning: a comparison of two methods. Epilepsy Res 97:124–132. https://doi.org/10.1016/j.eplepsyres.2011.07.019 CrossRefGoogle Scholar
- 10.Winston GP (2012) The physical and biological basis of quantitative parameters derived from diffusion MRI. Quant Imaging Med Surg 2:254–265. https://doi.org/10.3978/j.issn.2223-4292.2012.12.05 Google Scholar
- 12.Winston GP, Mancini L, Stretton J, Ashmore J, Symms MR, Duncan JS, Yousry TA (2011) Diffusion tensor imaging tractography of the optic radiation for epilepsy surgical planning: a comparison of two methods. Epilepsy Res 97:124–132. https://doi.org/10.1016/j.eplepsyres.2011.07.019 CrossRefGoogle Scholar
- 15.Lilja Y, Nilsson DT (2015) Strengths and limitations of tractography methods to identify the optic radiation for epilepsy surgery. Quant Imaging Med Surg 5:288–299. https://doi.org/10.3978/j.issn.2223-4292.2015.01.08 Google Scholar
- 20.Ghizoni E, Matias RN, Lieber S, de Campos BM, Yasuda CL, de Souza JPSAS, Pereira PC, Amato Filho ACS, Joaquim AF, Lopes TM, Tedeschi H, Cendes F (2017) Clinical and imaging evaluation of transuncus selective amygdalohippocampectomy. World Neurosurg 100:665–674. https://doi.org/10.1016/j.wneu.2016.11.056 CrossRefGoogle Scholar
- 22.Walsh TJ (2011) Visual fields: examination and interpretation. Oxford University Press, New YorkGoogle Scholar
- 25.Winston GP (2012) The physical and biological basis of quantitative parameters derived from diffusion MRI. Quant Imaging Med Surg 2:254–265. https://doi.org/10.3978/j.issn.2223-4292.2012.12.05 Google Scholar
- 30.Winston GP, Daga P, White MJ, Micallef C, Miserocchi A, Mancini L, Modat M, Stretton J, Sidhu MK, Symms MR, Lythgoe DJ, Thornton J, Yousry TA, Ourselin S, Duncan JS, McEvoy AW (2014) Preventing visual field deficits from neurosurgery. Neurology 83:604–611. https://doi.org/10.1212/WNL.0000000000000685 CrossRefGoogle Scholar
- 32.Heijl A (1989) The effect of perimetric experience in normal subjects. Arch Ophthalmol 107:81. https://doi.org/10.1001/archopht.1989.01070010083032 CrossRefGoogle Scholar
- 34.Wild JM, Pacey IE, O’Neill EC, Cunliffe IA (1999) The SITA perimetric threshold algorithms in glaucoma. Invest Ophthalmol Vis Sci 40:1998–2009Google Scholar
- 38.Wild JM, Pacey IE, Hancock SA, Cunliffe IA (1999) Between-algorithm, between-individual differences in normal perimetric sensitivity: full threshold, FASTPAC, and SITA. Swedish Interactive Threshold algorithm. Invest Ophthalmol Vis Sci 40:1152–1161Google Scholar
- 39.Artes PH, Iwase A, Ohno Y, Kitazawa Y, Chauhan BC (2002) Properties of perimetric threshold estimates from full threshold, SITA standard, and SITA fast strategies. Invest Ophthalmol Vis Sci 43:2654–2659Google Scholar
- 44.Fraser JA, Newman NJ, Biousse V (2011) Disorders of the optic tract, radiation, and occipital lobe. Handb Clin Neurol 102:205–221. https://doi.org/10.1016/B978-0-444-52903-9.00014-5 CrossRefGoogle Scholar