Visual evoked potentials’ responses in hypothyroidism and hyperthyroidism
Keywords:Hyperthyroidism, Hypothyroidism, Optic neuropathy, Visual evoked potential
Background: Visual Evoked Potentials (VEP) provides important diagnostic and prognostic information regarding the functional integrity of the visual system. This study, describes the effects of less or excess thyroid hormones of adults in visual conduction that helps to know the progression to neurological functional defects.
Methods: The study was done in 75 consenting subjects (hypothyroid = 24, hyperthyroid = 25, euthyroid = 26). The VEP parameters N75, P100, N145 latencies and its amplitudes within different thyroid status (hypothyroidism, hyperthyroidism and euthyroidism) were compared. One way ANOVA was used to compare VEP parameters among three groups and Pearson’s correlation to find relation between thyroid hormones and VEP parameters.
Results: There was positive correlation of 0.335, 0.338 and 0.301 between amplitudes of N75, P100 and N145 waves and fT3 hormone respectively. Furthermore, fT4 showed a positive correlation of 0.186 and 0.185 with the wave amplitudes of N75 and N145 waves respectively and negative correlation of TSH levels of -0.492, -0.280, -0.397 with amplitudes of N75, P100, N145 waves respectively. Hyperthyroid group had higher in VEP latency than euthyroid group in N75 (73±5.77 vs. 68.54±4.32), P100 (106.42±9.74 vs. 100.94±8.17) and N145 (153.03±16.39 vs. 144.37±7.02) waves. Similarly, hypothyroid group had higher in VEP latency than euthyroid group in N75 (72.12±6.34 vs. 68.54±4.32) wave.
Conclusions: Both hypothyroidism and hyperthyroidism led to conduction delay in adults, possibly adversely affecting function of myelin. The prominent visual evoked potential abnormalities in hyperthyroidism and less change in hypothyroidism show that the visual neuropathy is more common in hyperthyroidism.
Bernal J. Thyroid hormones and brain development. Vitamins and hormones. 2005;71:95-122.
Dietzel ID, Mohanasundaram S, Niederkinkhaus V, Hoffmann G, Meyer JW, Reiners C, et. al. Thyroid hormone effects on sensory perception, mental speed, neuronal excitability and ion channel regulation. In Thyroid Hormone. 2012:101-8.
Ahmed OM, El-Gareib A, El-Bakry A, El-Tawab SA, Ahmed R. Thyroid hormones states and brain development interactions. Int J Developmental Neurosci. 2008;26(2):147-209.
Avramides A, Papamargaritis K, Mavromatis I, Saddic G, Vyzantiadis A, Milonas I. Visual evoked potentials in hypothyroid and hyperthyroid patients before and after achievement of euthyroidism. J Endocrinological Investigation. 1992;15(10):749-53.
Aminoff MJ. Aminoff's electrodiagnosis in clinical neurology: Elsevier Health Sciences; 2012:477-8.
Brigell M, Bach M, Barber C, Kawasaki K, Kooijman A. Guidelines for calibration of stimulus and recording parameters used in clinical electrophysiology of vision. Documenta Ophthalmologica. 1998;95(1):1-14.
Odom JV, Bach M, Brigell M, Holder GE, McCulloch DL, Mizota A, et al. ISCEV standard for clinical visual evoked potentials:(2016 update). Documenta Ophthalmologica. 2016;133(1):1-9.
Kapoor R, Desouza L, Nanavaty I, Kernie S, Vaidya V. Thyroid hormone accelerates the differentiation of adult hippocampal progenitors. J Neuroendocrinol. 2012;24(9):1259-71.
Jämsén K. Thyroid disease, a risk factor for optic neuropathy mimicking normal‐tension glaucoma. Acta Ophthalmol Scandinavica. 1996;74(5):456-60.
Tamburini G, Tacconi P, Ferrigno P, Cannas A, Massa G, Mastinu R, et al. Visual evoked potentials in hypothyroidism: a long-term evaluation. Electromyog Clin Neurophysiol. 1998;38(4):201-5.
Tsaloumas M, Good P, Burdon M, Mission G. Flash and pattern visual evoked potentials in the diagnosis and monitoring of dysthyroid optic neuropathy. Eye-An Int J Ophthalmol. 1994;8(6):638-45.
Thuangtong A, Wangvarunyoo C, Kunavisarut T, Phithakphaosakul N. Visual Evoked Potentials (VEP) in Graves’ Disease Patients in Siriraj Hospital. Siriraj Med J. 2017;65(5):128-31.
Aprajita GS, Aggarwal S. Visual evoked potentials in overt hypothyroid patients before and after achievement of euthyroidism. Indian J Endocrinol Meta. 2017;21(3):419.
Khedr EM, El Toony LF, Tarkhan MN, Abdella G. Peripheral and central nervous system alterations in hypothyroidism: electrophysiological findings. Neuropsychobiol. 2000;41(2):88-94.
Ladenson PW, Stakes JW, Ridgway EC. Reversible alteration of the visual evoked potential in hypothyroidism. Ame J Med. 1984;77(6):1010-4.
Mitchell KW, Wood CM, Howe JW. Pattern visual evoked potentials in hyperthyroidism. Br J Ophthalmol. 1988;72(7):534-7.
Salvi M, Spaggiari E, Neri F, Macaluso C, Gardini E, Ferrozzi F, et al. The study of visual evoked potentials in patients with thyroid-associated ophthalmopathy identifies asymptomatic optic nerve involvement. J Clin Endocrinol Metab. 1997;82(4):1027-30.
Nazliel B, Akbay E, Irkeç C, Yetkin I, Ersoy R, Törüner F. Pattern visual evoked potential (PVEP) evaluation in hypothyroidism. J Endocrinol Investigation. 2002;25(11):955-8.