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Boomi Quchan Atigh S, Sadat Shakeri H, Esmaily H, Darvishi A, Hamidi A, Heravian Shandiz J. Evaluation of visual functions in Iranian hypothyroid adults. Endocrinol Diabetes Metab 2022; 6:e393. [PMID: 36519206 PMCID: PMC9836240 DOI: 10.1002/edm2.393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 10/07/2022] [Accepted: 11/06/2022] [Indexed: 12/23/2022] Open
Abstract
INTRODUCTION The aim of this study was to investigate the effects of hypothyroidism on visual functions such as visual acuity, refractive errors, colour vision, and contrast sensitivity, among hypothyroid adults. METHODS Forty-three patients with clinical hypothyroidism along with 43 age- and sex-matched healthy individuals underwent visual examinations, including visual acuity, refractive errors, eye deviations with the cover test, colour vision with the D15 test, and contrast sensitivity with Pelli-Robson test. RESULTS It was indicated that visual acuity, refractive errors, phoria, and colour vision had no significant difference between the hypothyroid and control groups. Contrast sensitivity decreased in hypothyroid subjects as compared with controls. The mean values of binocular contrast sensitivity were 1.85 ± 0.09 log in the hypothyroid group and 1.93 ± 0.09 log in controls, which showed a statistically significant difference (p = .03). CONCLUSIONS Our findings illustrated a reduced contrast sensitivity in adult hypothyroidism. Since CS is related to functioning and quality of life, a comprehensive and detailed eye examination may be beneficial for hypothyroidism patients.
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Affiliation(s)
- Somayyeh Boomi Quchan Atigh
- Refractive Errors Research CenterMashhad University of Medical SciencesMashhadIran,Department of Optometry, School of Paramedical ScienceMashhad University of Medical SciencesMashhadIran
| | | | - Habibollah Esmaily
- Social Determinants of Health Research CenterMashhad University of Medical SciencesMashhadIran
| | - Azam Darvishi
- Department of Optometry, School of Paramedical ScienceMashhad University of Medical SciencesMashhadIran
| | - Aghdas Hamidi
- Department of Optometry, School of Paramedical ScienceMashhad University of Medical SciencesMashhadIran
| | - Javad Heravian Shandiz
- Refractive Errors Research CenterMashhad University of Medical SciencesMashhadIran,Department of Optometry, School of Paramedical ScienceMashhad University of Medical SciencesMashhadIran
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Abstract
BACKGROUND Both overt hypothyroidism as well as minor elevations of serum thyrotropin (TSH) levels associated with thyroid hormones within their respective reference ranges (termed subclinical hypothyroidism) are relatively common in older individuals. There is growing evidence that treatment of subclinical hypothyroidism may not be beneficial, particularly in an older person. These findings are relevant at a time when treatment with thyroid hormones is increasing and more than 10-15% of people aged over 80 years are prescribed levothyroxine replacement therapy. MAIN BODY The prevalence of hypothyroidism increases with age. However, the reference range for TSH also rises with age, as the population distribution of TSH concentration progressively rises with age. Furthermore, there is evidence to suggest that minor TSH elevations are not associated with important outcomes such as impaired quality of life, symptoms, cognition, cardiovascular events and mortality in older individuals. There is also evidence that treatment of mild subclinical hypothyroidism may not benefit quality of life and/or symptoms in older people. It is unknown whether treatment targets should be reset depending on the age of the patient. It is likely that some older patients with non-specific symptoms and incidental mild subclinical hypothyroidism may be treated with thyroid hormones and could potentially be harmed as a result. This article reviews the current literature pertaining to hypothyroidism with a special emphasis on the older individual and assesses the risk/benefit impact of contemporary management on outcomes in this age group. CONCLUSIONS Current evidence suggests that threshold for treating mild subclinical hypothyroidism in older people should be high. It is reasonable to aim for a higher TSH target in treated older hypothyroid patients as their thyroid hormone requirements may be lower. In addition, age-appropriate TSH reference ranges should be considered in the diagnostic pathway of identifying individuals at risk of developing hypothyroidism. Appropriately designed and powered randomised controlled trials are required to confirm risk/benefit of treatment of subclinical hypothyroidism in older people. Until the results of such RCTs are available to guide clinical management international guidelines should be followed that advocate a conservative policy in the management of mild subclinical hypothyroidism in older individuals.
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Affiliation(s)
- Owain Leng
- Department of Endocrinology, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE1 4LP UK
| | - Salman Razvi
- Department of Endocrinology, Gateshead Health NHS Foundation Trust, Queen Elizabeth Hospital, Gateshead, Gateshead, NE9 6SX UK
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, NE1 3BZ UK
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Azimi A, Bonakdaran S, Heravian J, Layegh P, Yazdani N, Alborzi M. Pattern visual evoked potential in hypothyroid patients. Doc Ophthalmol 2019; 138:77-84. [PMID: 30680490 DOI: 10.1007/s10633-019-09670-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 01/07/2019] [Indexed: 10/27/2022]
Abstract
PURPOSE To investigate the functional integrity of visual pathway in hypothyroid patients by pattern visual evoked potential (PVEP). METHODS We enrolled 36 female patients with history of hypothyroidism (18 overt and 18 subclinical) aged 20 to 60 years and 36 healthy women of similar age (control group). All subjects had a complete ophthalmic examination. For VEP testing, subjects were exposed to checks subtending a visual angle of 15 and 60 min of arc. RESULTS For the 15 min of arc check size, the mean P100 latency was significantly delayed (113 milliseconds (ms)) and amplitude significantly reduced (9.2 microvolts (µv)) in the hypothyroidism group compared with controls (109.6 ms and 11.6 µv, respectively). For this 15' check size, the group differences were related to significantly increased latency and reduced amplitude of responses in the group with overt hypothyroidism compared with controls. There was no difference between the groups (hypothyroid vs control) with 60 min of arc check size. There was a significant correlation between severity of the disease and PVEP component. CONCLUSIONS In conclusion, low levels of circulating hypothyroid hormone are associated with delay in the pattern VEP to small check sizes. This CNS involvement worsens in patients with greater severity and duration of hypothyroidism.
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Affiliation(s)
- Abbas Azimi
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Azadi Square, Pardis Ferdowsi, 91779-48964, Mashhad, Iran.,Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Shokoufeh Bonakdaran
- Endocrine Research Center, Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Javad Heravian
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Azadi Square, Pardis Ferdowsi, 91779-48964, Mashhad, Iran.,Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Parvin Layegh
- Endocrine Research Center, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Negareh Yazdani
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Azadi Square, Pardis Ferdowsi, 91779-48964, Mashhad, Iran.,Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Maryam Alborzi
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Azadi Square, Pardis Ferdowsi, 91779-48964, Mashhad, Iran.
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Sharma G, Aggarwal S. Visual Evoked Potentials in Overt Hypothyroid Patients before and after Achievement of Euthyroidism. Indian J Endocrinol Metab 2017; 21:419-423. [PMID: 28553598 PMCID: PMC5434726 DOI: 10.4103/ijem.ijem_366_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Visual evoked potential (VEP) measures the time taken for visual stimulus to travel from the eye to the occipital cortex. Hypothyroidism affects the central nervous system (CNS) through its role in gene expression, myelin production, axonal transportation, and neurotransmitters. Delay in the conduction of impulses results in abnormal VEP. OBJECTIVE Correlate the electrophysiological findings of VEP in newly diagnosed treatment-naive hypothyroid patients before and after 3 months of treatment and to find the correlation with serum thyroid-stimulating hormone (TSH) levels. MATERIALS AND METHODS VEP was measured using Recorders and Medicare Systems Electromyograph Evoked Potential Mark II machine in 30 patients (serum TSH ≥10 mIU/L) between 18 and 50 years of age who were followed up after 3 months of treatment. RESULTS The mean age (±standard deviation) of the patients was 31.8 (±8.3) years. There was prolongation of VEP latencies which tends to decrease following hormone replacement therapy. It was found to be most significant for P100 (ms) waveform (P < 0.001). The amplitude (P100-N75 mV) which was decreased in hypothyroid patients showed improvement following achievement of euthyroidism. Significant positive correlation was found between P100, N75 latency and pretreatment serum TSH levels. CONCLUSION Hypothyroid patients may have changes in the latencies and the amplitude of VEP which are reversible to a great extent with thyroxine replacement therapy. VEP thus acts as a dependable marker for CNS affection in thyroid diseases to detect subtle early changes and to assess the response to treatment in correlation with the clinical improvement.
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Affiliation(s)
- Geetanjali Sharma
- Department of Physiology, Pt. B. D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
| | - Sameer Aggarwal
- Department of Endocrinology, Pt. B. D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
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Abstract
Thyroid disorders are common in the general population and in hospitalized patients. Thyroid disease may present first with neurological complications or else may occur concurrently in patients suffering other neurological disorders, particularly those with an autoimmune etiology. For this reason neurologists will commonly encounter patients with thyroid disease. This chapter provides an overview of the neurological complications and associations of disorders of the thyroid gland. Particular emphasis is placed on conditions such as thyrotoxic periodic paralysis and myxedema coma in which the underlying thyroid disorder may be occult leading to a first, often emergency, presentation to a neurologist. Information about clinical features, diagnosis, pathogenesis, therapy, and prognosis is provided. Emphasis is placed on those aspects most likely to be relevant to the practicing neurologist and the interested reader is directed to references to good, recent review articles for further information.
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Affiliation(s)
- Clare A Wood-Allum
- Sheffield Institute for Translational Neuroscience, University of Sheffield and Department of Neurology, Royal Hallamshire Hospital, Sheffield, UK
| | - Pamela J Shaw
- Sheffield Institute for Translational Neuroscience, University of Sheffield and Department of Neurology, Royal Hallamshire Hospital, Sheffield, UK.
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Electromyographic evaluation of blink reflex as a tool for early diagnosis of neurological dysfunction in patients of hypothyroidism. Ann Neurosci 2013; 20:95-8. [PMID: 25206024 PMCID: PMC4117124 DOI: 10.5214/ans.0972.7531.200304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 03/05/2013] [Accepted: 05/10/2013] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Neurological dysfunction is an important consequence of hypothyroidism. Some of the neurologic manifestations of hypothyroidism include somnolence, lethargy, impaired memory and concentration, depression and entrapment neuropathy. Rarer but reversible neurological manifestations include cerebellar ataxia, psychosis, dementia and myxedema coma. PURPOSE The aim of the present study was to evaluate the usefulness of the blink reflex as a method for obtaining an early diagnosis of central nervous system dysfunction in hypothyroid patients who do not have signs or symptoms of nervous system dysfunction. METHODS Forty-eight patients with mean age 40 (± 11), with newly diagnosed primary hypothyroidism and 20 healthy control subjects were included in the study. The patients were divided into subclinical and overt hypothyroidism. Patients with normal T3/T4 with elevated TSH were considered subclinical hypothyroids. For blink reflex testing, subjects lay supine on a bed in a warm room with eyes gently closed. Recordings were performed with an EMG machine (Nihon Kohdeni'Neuropack), with a filter setting of 20 Hz to 10 kHz, using an analysis time of 50 ms. Recordings were performed with surface recording electrodes (Dantec 13K60, Copenhagen, Denmark). RESULTS Second ipsilateral response (R2I) and second contralateral response (R2C) latencies in hypothyroidism were prolonged relative to controls, and the differences were statistically significant (P<0.001 and P<0.001, respectively). Latency of Rl, R2I, and R2C did not correlate linearly free T3, free T4, or TSH values in the hypothyroid group. CONCLUSION The finding of abnormal blink reflex responses in hypothyroid individuals raises the notion that they may be useful in detecting early changes and in the follow-up of the patients with the disorder.
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Evaluation of multifocal visual evoked potentials in patients with Graves' orbitopathy and subclinical optic nerve involvement. Doc Ophthalmol 2012; 125:11-9. [PMID: 22581376 DOI: 10.1007/s10633-012-9325-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 03/29/2012] [Indexed: 10/28/2022]
Abstract
Dysthyroid optic neuropathy is the most serious, although infrequent (8-10 %) complication in Graves' orbitopathy (GO). It is known that early stages of compressive optic neuropathy may produce reversible visual field defects, suggesting axoplasmic stasis rather than ganglion cell death. This observational, cross-sectional, case-control study assessed 34 consecutive patients (65 eyes) with Graves' hyperthyroidism and longstanding GO and 31 age-matched control subjects. The patients' multifocal visual evoked potentials (mfVEP) were compared to their clinical and psychophysical (standard automated perimetry [SAP]) and structural (optic coherence tomography [OCT]) diagnostic test data. Abnormal cluster defects were found in 12.3 % and 3.1 % of eyes on the interocular and monocular amplitude analysis mfVEP probability plots, respectively. As well, mfVEP latencies delays were found in 13.8 and 20 % of eyes on the interocular and monocular analysis probability plots, respectively. Interestingly, 19 % of patients with GO had ocular hypertension, and a strong correlation between intraocular pressure measured at upgaze and mfVEP latency was found. MfVEP amplitudes and visual acuity were significantly related to each other (P < 0.05), but not with the latencies delays. However, relationships between the interocular or monocular mfVEP amplitudes and latencies analysis and SAP indices or OCT data were not statistically significant. One-third of our patients with GO showed changes in the mfVEP, indicating significant subclinical optic nerve dysfunction. In this sense, the mfVEP may be a useful diagnostic tool in the clinic for early diagnosis and monitoring of optic nerve function abnormalities in patients with GO.
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Evaluation of Auditory Event-Related Potentials in Hyperthyroid and Hypothyroid Patients. ACTA ACUST UNITED AC 2008. [DOI: 10.1097/ten.0b013e31819032e4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Nazliel B, Akbay E, Irkeç C, Yetkin I, Ersoy R, Törüner F. Pattern visual evoked potential (PVEP) evaluation in hypothyroidism. J Endocrinol Invest 2002; 25:955-8. [PMID: 12553554 DOI: 10.1007/bf03344067] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Dysfunction of the central nervous system (CNS) is an important consequence of thyroid hormone deficiency. Evoked potentials like visual evoked potentials (VEP) provide a reliable and objective measure of function in related sensory system and tracts. In this study pattern-shift VEP (PVEP) recordings were performed on 48 newly diagnosed hypothyroid patients. Twenty-four had sub-clinical and 24 had overt hypothyroidism. None of the patients had clinical symptoms or signs referable to CNS dysfunction. Their mean age was 44+/-12 yr. The response to pattern stimulation on the normal control subjects was a triphasic response with a prominent positive wave (P100) with a peak latency of 84-105 (mean: 96+/-4) milliseconds (ms). In patients with hypothyroidism mean P100 latency was (mean: 97+/-6) ms and the difference between the 2 groups was not statistically significant. (p>0.05) Delays above the average latency +/-2.5 SD of the mean of the control subjects was defined as a criteria for an abnormality. According to defined criteria 6 (12.5%) patients demonstrated abnormal PVEP at least on one tested side. Previous studies conducted on small patient populations stated there is high percentage of VEP abnormalities in hypothyroid patients. However, this fact was not confirmed by our study. We believe abnormalities of PVEP will be more prominent in untreated patients in the advanced stage of the disease, or in patients who have a neurological involvement; such as apathy, impaired memory or cerebellar dysfunction. Consecutive studies, in a more clearly defined and selected patient population, are needed to confirm and settle this issue.
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Affiliation(s)
- B Nazliel
- Faculty of Medicine, Gazi University, Ankara, Turkey.
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10
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Dickinson AJ, Perros P. Controversies in the clinical evaluation of active thyroid-associated orbitopathy: use of a detailed protocol with comparative photographs for objective assessment. Clin Endocrinol (Oxf) 2001; 55:283-303. [PMID: 11589671 DOI: 10.1046/j.1365-2265.2001.01349.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Despite many learned publications over recent decades, the assessment of active thyroid-associated orbitopathy (TAO) remains difficult and controversial. There are no biochemical, immunological or imaging investigations which can identify active disease reliably, and clinical assessment is still of paramount importance. We therefore review the strengths and weaknesses of all methods of clinical assessment. A new atlas for clinical assessment of soft tissue signs has been developed, and its reproducibility assessed. It details a suggested protocol that could help standardize descriptions of TAO and allow more objective assessment of its activity and severity. This is relevant to general endocrinologists, who have a crucial role in the identification of patients who require ophthalmological assessment. Certain aspects are more relevant to ophthalmologists and endocrinologists who have a special clinical and research interest in TAO. Unless a reproducible system of assessment is devised and widely adopted, it will remain difficult to interpret research meaningfully, particularly if results appear to contradict.
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Affiliation(s)
- A J Dickinson
- Department of Ophthalmology, Newcastle Hospitals NHS Trust, Newcastle upon Tyne, UK.
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Barradas PC, Ferraz AS, Ferreira AA, Daumas RP, Moura EG. 2'3'Cyclic nucleotide 3'phosphodiesterase immunohistochemistry shows an impairment on myelin compaction in hypothyroid rats. Int J Dev Neurosci 2000; 18:887-92. [PMID: 11154857 DOI: 10.1016/s0736-5748(00)00028-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
The effects of hypothyroidism on oligodendroglial differentiation and myelination are for the first time studied by immunohistochemical localization of an early oligodendroglial marker, the 2'3'cyclic nucleotide 3'phosphodiesterase (E.C. 3.1.4.37-CNPase), in developing rats. Two groups received methimazol; one during gestation (H) and another postnatally (PN). One H sub-group received thyroxine after birth (T). We observed a delay in CNPase expression followed by a decrease in the number of CNPase immunoreactive fibers in both H and PN groups. The T sub-group was not different from controls. Furthermore, the immunoreactive fibers, in mature hypothyroid animals, showed a continuous pattern of staining in contrast with a discontinuous one in controls. Myelinogenesis is a highly regulated timed event. CNPase links myelin related proteins to the cytoskeleton also interacting with membrane lipids during extension and wrapping of the oligodendroglial process around the axon (ensheathment phase). In mature myelinated fiber the CNPase is absent from compact myelin sheath, being located only in the inner and outer loops and in paranodal loops. Thus, our data suggest a disorder in myelin compaction and point once more to the post-natal period as critical for the mechanisms that are thyroid hormone regulated in myelinogenesis.
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Affiliation(s)
- P C Barradas
- Depto. Farmacologia e Psicobiologia, Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
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Dolu N, Süer C, Ozesmi C, Keleştimur F, Ozcan Y. Electrodermal activity in hypothyroid patients and healthy subjects. Thyroid 1999; 9:787-90. [PMID: 10482371 DOI: 10.1089/thy.1999.9.787] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The involvement of the central nervous system either in hypothyroidism or in hyperthyroidim has previously been shown on the basis of visual, auditory, somatosensory, and central motor evoked potential studies by some investigators. In to our previous study, we found that abnormal electrodermal activity in nonmedicated hyperthyroid patients was not associated with psychiatric symptoms. In this study, our purpose was to investigate whether hypothyroidism results in electrodermal abnormalities in the absence of measurable psychiatric symptoms. Electrodermal activity was recorded with a skin conductance unit connected to a personal computer. Basal levels of electrodermal activity and responsiveness to repeated acoustic stimulation were studied in 14 nonmedicated hypothyroid patients and 14 healthy controls. Psychiatric rating scores indicated that patients and healthy controls had normal levels of anxiety and depression. Hypothyroid patients had lower skin conductance levels, lower fluctation rates and prolonged onset latencies compared with controls. None of the hypothyroid patients had amplitude changes. In conclusion, hypothyroid patients may have abnormal electrodermal activity that is related to the change of hypothalamic-pituitary-thyroid axis function, without associated psychiatric symptoms.
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Affiliation(s)
- N Dolu
- Department of Physiology, Faculty of Medicine, Erciyes University, Kayseri, Turkey.
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Dolu N, Süer C, Ozesmi C, Keleştimur F, Eşel E. Electrodermal activity in nonmedicated hyperthyroid patients having no depressive symptoms. Biol Psychiatry 1997; 42:1024-9. [PMID: 9386854 DOI: 10.1016/s0006-3223(96)00551-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The aim of the present study was to investigate whether the alteration in hypothalamic-pituitary-thyroid axis function results in electrodermal abnormality without causing marked psychiatric manifestations or not. Electrodermal activity was recorded with the skin conductance unit and IBM-AT computer. Basal levels of electrodermal activity (EDA), as well as responsivity to repeated insignificant acoustic stimulation were studied in 24 nonmedicated hyperthyroid patients and 35 healthy controls. The outcome of psychiatric rating scores indicated that patients had low anxiety scores and normal depression scores. The basal levels of thyroid hormones were higher in patients, when compared with the control group. On the analysis of EDA, we found lower onset latency and duration of the skin conductance response and higher skin conductance level in nonmedicated patients than healthy controls. The results above provide supporting evidence that the change of hypothalamic-pituitary-thyroid axis function results in abnormal EDA, without causing marked psychiatric manifestations.
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Affiliation(s)
- N Dolu
- Department of Physiology, Erciyes University, Faculty of Medicine, Kayseri, Turkey
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Ozata M, Ozkardes A, Corakci A, Beyhan Z, Gundogan MA. Event-Related Brain Potentials in Patients with Hypothyroidism. Endocr Pract 1997; 3:349-52. [PMID: 15251772 DOI: 10.4158/ep.3.6.349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To evaluate the cognitive function of patients with hypothyroidism, based on long-latency auditory event-related potentials (ERPs). METHODS We investigated alterations of P300 latency in patients with hypothyroidism before treatment and after restoration of euthyroidism. ERPs were elicited in 14 untreated patients with hypothyroidism (mean age, 26.71 +/- 2.39 years) and in a group of 30 control subjects with comparable mean age, sex distribution, and educational level. ERP recordings were repeated at 1 and 6 months after attainment of euthyroidism. RESULTS Untreated patients with hypothyroidism had longer P300 and N1 wave latencies in comparison with those in the control subjects (P = 0.003 and P = 0.018, respectively). The mean P300 latencies did not change significantly 1 month after restoration of euthyroidism. At 6 months after attainment of euthyroidism, however, the mean P300 latencies returned to normal values, similar to those in the control subjects. CONCLUSION We conclude that P300 latencies are impaired in patients with hypothyroidism, which is indicative of cognitive dysfunction. These alterations, however, may be reversed 6 months after attainment of euthyroidism.
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Affiliation(s)
- M Ozata
- Department of Endocrinology and Metabolism, Gulhane School of Medicine, Etlik-Ankara 06018, Turkey
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15
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Spadea L, Bianco G, Dragani T, Balestrazzi E. Early detection of P-VEP and PERG changes in ophthalmic Graves' disease. Graefes Arch Clin Exp Ophthalmol 1997; 235:501-5. [PMID: 9285219 DOI: 10.1007/bf00947007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND In Graves' disease the optic neuropathy (ON) is due to direct compression of the nerve and/or of its blood supply. The aim of the present study was to detect early changes in the visual functions of patients affected by ophthalmic Graves' disease (OGD) by using electrophysiological tests (P-VEP and PERG). METHODS We studied 50 OGD patients who were in a range between class 2 and class 5 according to the Donaldson-American Thyroid Association classification, i.e. had no evident ON and normal visual acuity. We recorded transient reversal PERG and P-VEP in response to the stimulation of one eye at three spatial frequencies (2.2, 1.1 and 0.5 c/d). RESULTS Our results showed a statistically significant reduction in PERG amplitude in class 5, while the P-VEP amplitude was already reduced in class 2. CONCLUSION The electrofunctional tests were useful to detect small changes in the visual function of patients affected by initial stages of OGD. Therefore, P-VEP and PERG recordings appear to be a useful tool for early diagnosis of the optic nerve involvement in Graves' disease.
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Affiliation(s)
- L Spadea
- University of L'Aquila, Department of Ophthalmology, Italy
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16
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Ozata M, Ozkardes A, Dolu H, Corakçi A, Yardim M, Gundogan MA. Evaluation of central motor conduction in hypothyroid and hyperthyroid patients. J Endocrinol Invest 1996; 19:670-7. [PMID: 9007698 DOI: 10.1007/bf03349037] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Deficiency or excess of thyroid hormones is associated with central nervous system (CNS) disturbances. Although the CNS involvement either in hypothyroidism or in hyperthyroidism have previously been shown on the basis of visual, auditory and somatosensory evoked potentials studies, less is known about the function of central motor pathways in both disorders. We studied the motor evoked potentials (MEPs) following the magnetic stimulation of the motor cortex and spinal roots in 20 patients with hypothyroidism and in 19 patients with hyperthyroidism both before treatment and after they became euthyroid and compared with findings in 20 age-, sex- and height-matched control subjects. Disease duration (expressed as time from diagnosis of diseases to the time of neurological testing) is less than one month in both disorders. Central motor conduction time (CMCT) was determined as the differences between MEPs latencies after cortical and spinal stimulation. The mean CMCTs before treatment in hypothyroid patients (8.31 +/- 1.52 msec.) and in hyperthyroid patients (7.92 +/- 1.06 msec.) were significantly prolonged as compared to those in normal controls (6.82 +/- 0.83 msec. p = 0.002 and p = 0.004, respectively). Four of the 20 (20.0%) hypothyroid patients and 2 of 19 (10.5%) hyperthyroid patients had abnormal CMCT (values exceeding mean +2.5 SD of normal control). The mean CMCT values in both groups were not significantly decreased after euthyroidism was achieved, although a tendency of the decrease in CMCT was observed. Improvement of CMCT abnormalities was observed in 1 of 4 hypothyroid patients and in one of 2 patients with hyperthyroidism, who had CMCT abnormalities before treatments, after they became euthyroid. No correlation was found between CMCT and free T3, free T4, or TSH levels as well as the onset age, the severity of the diseases or the disease duration in both disorders. We conclude that abnormal CMCT could be documented in few patients in both disorders. However, these alterations could not be improved completely after restoration of euthyrodism. Thus, it remains to be determined if long-term treatment would completely improve CMCT abnormalities in both disorders. Since abnormal CMCT values in both disorders were observed only in few patients, our results also suggest that CMCT measurement does not have, at present time, a clinical usefulness to assess the peripheral action of thyroid hormones. Thus, the data obtained need a more extensive evaluation.
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Affiliation(s)
- M Ozata
- Department of Endocrinology and Metabolism, Gulhane School of Medicine, Etlik-Ankara, Turkey
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Ozkardes A, Ozata M, Beyhan Z, Corakci A, Vural O, Yardim M, Gundogan MA. Acute hypothyroidism leads to reversible alterations in central nervous system as revealed by somatosensory evoked potentials. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1996; 100:500-4. [PMID: 8980414 DOI: 10.1016/s0168-5597(96)96520-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Although functional alterations in the central nervous system (CNS) and peripheral nerves are well documented in overt hypothyroidism, little is known about alterations of CNS in acute hypothyroidism. Sixteen patients with differentiated thyroid carcinoma were studied when prepared for radioiodine scanning after stopping levothyroxine (L-T4) therapy for 6 weeks to determine whether acute hypothyroidism leads to alteration in somatosensory evoked potentials (SSEPs). Repeat SSEPs were performed on the same patients at 6 months following L-T4 therapy when patients were euthyroid. Neurophysiological findings were compared with a group of 20 normal controls with no history of thyroid disease. Peripheral and central conduction in the median and tibial nerve stimulated SSEPs studied. A significant prolongation of central conduction time in SSEPs was found in patients with acute hypothyroidism when compared to those in control subjects. Abnormal latencies were not correlated with thyroid hormone levels. These neurophysiologic abnormalities were completely restored to normal at 6 months after L-T4 therapy. We conclude that acute hypothyroidism leads to reversible alterations in CNS as determined by SSEP recordings. Our results also suggest that SSEPs could be useful tests to monitor functional alteration of the CNS in acute hypothyroidism.
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Affiliation(s)
- A Ozkardes
- Department of Neurology, Gulhane School of Medicine, Etlik-Ankara, Turkey
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Abstract
To evaluate the effect of thyroid hormone on the retina in the adult male rat, morphometric and autoradiographic studies were made. Four days after an intravenous pulse injection of L-[3H]-leucine into adult male rats, the eyeballs were removed and the autoradiogram made. Two weeks after thyroidectomy, the length of photoreceptor cell inner segments was significantly decreased, but that of the outer segments did not change. Daily supplement of T4 (100 microg/kg sc twice for 2 days) before L-[3H]-leucine injection did not restore the decrease in the length. The silver grains of radioactive material distributed in the outer segment were divided into 3 equal portions. Thyroidectomy significantly increased the number of grains in the basal portion near the inner layer indicating a reduction in the renewal rate of the outer segment, but the T4 supplement did not restore the reduction in the renewal rate. These findings suggest that thyroid hormone is required to maintain the rate of renewal of the photoreceptor cell outer segment but the hormone supplement did not rapidly restore the renewal rate.
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Affiliation(s)
- M Takeda
- Department of Physiology, School of Dentistry at Tokyo, Nippon Dental University, Japan
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19
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Analysis of evoked potentials. Clin Neurophysiol 1995. [DOI: 10.1016/b978-0-7506-1183-1.50028-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
To characterize the effect of thyroid hormone on the central nervous system in adult rats, we recorded evoked potentials by photic (VEP) and electrical stimulation in normal, thyroidectomized (Tx) and T3- or T4-supplemented (Tx-T3, Tx-T4) male adult rats under pentobarbital anesthesia. The latencies of VEPs recorded in the visual cortex (VC) and lateral geniculate nucleus (LGN), and the b-waves of the electroretinograms (ERG) of these three groups were compared. A significant prolongation of the latency of VEP by photic stimulation (flash light intensity 2J, 0.2 Hz) in the VC was observed 14 to 28 days after thyroidectomy (27.9 +/- 0.4 vs. 33.4 +/- 0.43 msec, p < 0.01). Similar prolongations were also observed when those of the VEP in the LGN and the b-wave of the ERG were compared to those of normal rats (22.4 +/- 0.37 vs. 27.3 +/- 0.41 msec, p < 0.01; 21.8 +/- 0.21 vs. 25.3 +/- 0.41 msec, p < 0.01, respectively). The prolonged latencies observed in the VC, LGN, and ERG-b-wave were partially normalized 24 hr after T3 supplement (50 micrograms/kg, sc) and fairly restored to normal levels by 48 hr after T4 injection (100 micrograms/kg sc). The VEP latencies in the LGN and VC showed a positive correlation with the b-wave latency of the ERG in these three groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Takeda
- Department of Physiology, Medical School, Gunma University, Maebashi, Japan
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Setälä K, Raitta C, Välimäki M, Katevuo V, Lamberg BA. The value of visual evoked potentials in optic neuropathy of Graves' disease. J Endocrinol Invest 1992; 15:821-6. [PMID: 1291594 DOI: 10.1007/bf03348812] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Visual evoked potentials (VEP) were tested in patients with ophthalmopathy (OP) of Graves' disease (GD) before treatment and half-a-year and 5-7 yr after orbital decompression (7 patients) or retrobulbar irradiation (3 patients). Five patients not requiring treatment for OP and 16 healthy subjects served as controls. Treatment of OP was given on clinical grounds including decreased visual acuity (VA) indicating optic neuropathy. Before treatment VA was decreased in 5 out of 19 eyes whereas VEP were abnormal in all. The mean latency at N60 both in the operated (83.1 +/- 21.6 ms) and in the irradiated groups (80.9 +/- 7.0 ms) was significantly different from that in the untreated group (62.6 +/- 8.2 ms; p < 0.001) and the healthy subjects (58.9 +/- 6.3; p < 0.001). At P120 only the latency of the operated group differed significantly from that of the other groups (p < 0.001). There was a relationship between the eye muscle changes seen on CT scans and the ophthalmopathy score (according to the classification of the American Thyroid Association) and the latency both at N60 and P120. A change from a V-shape to a W-shape of the waves occurred more often in the treated patients before therapy than in the other groups. Two patients had multiphase VEP in both eyes which improved after treatment. After adequate clinical response the visual acuity improved in one of the 5 patients with initially depressed VA. VEP, initially abnormal in all, improved in 7 of the 19 eyes (37%) but further deterioration was observed in 8 (42%).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K Setälä
- Department for Ophthalmology, University Central Hospital, Helsinki, Finland
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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 Endocrinol Invest 1992; 15:749-53. [PMID: 1491123 DOI: 10.1007/bf03347646] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Thyroid hormone deficiency is frequently associated with central nervous system (CNS) disturbances such as mental retardation, convulsions, coma etc. Studies of quantitative changes in CNS in hypo- or hyperthyroidism are scarce. Evoked potentials is a good method of assessing the electrical response of the brain to different (visual, acoustic, somatosensory) stimuli and has been used extensively in the study of brain disturbances and to a lesser degree in metabolic diseases. We studied the visual evoked potentials (latency and amplitude) in 12 patients with hyperthyroidism and 15 patients with hypothyroidism, before treatment and after they became euthyroid. Four of the hyperthyroids (33%) had abnormally prolonged (> 104 msec) latencies before therapy. Two of them had clinical exophthalmos. No change was observed after euthyroidism was achieved. On the contrary 7 out of 15 (47%) hypothyroids had abnormally prolonged latencies which became normal in 4 when euthyroidism was achieved. Amplitude was lower than normal in 6 and became normal only in one of them after treatment. None of the hyperthyroid patients had amplitude changes. In conclusion, hypothyroid patients may have changes in the amplitude and/or the latency of visual evoked potentials which are reversible to a great extent with thyroxine. Evoked potentials is another method of studying in humans the metabolic effects of thyroxine deficiency in CNS.
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Affiliation(s)
- A Avramides
- Department of Endocrinology, Hippocration Hospital, Thessaloniki, Greece
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Osterweil D, Syndulko K, Cohen SN, Pettler-Jennings PD, Hershman JM, Cummings JL, Tourtellotte WW, Solomon DH. Cognitive function in non-demented older adults with hypothyroidism. J Am Geriatr Soc 1992; 40:325-35. [PMID: 1556359 DOI: 10.1111/j.1532-5415.1992.tb02130.x] [Citation(s) in RCA: 166] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
PURPOSE (1) to evaluate objectively changes in cognitive function and electrophysiologic characteristics associated with hypothyroidism of varying severity and duration in primarily older persons; (2) to determine whether these changes are reversible when a euthyroid state has been attained after treatment with thyroid hormone. SUBJECTS AND METHODS We enrolled 54 non-demented hypothyroid patients (31-99, mean 68.6 +/- 16.4 years) with biochemical evidence of hypothyroidism (38 had overt and 14 had minimal hypothyroidism) and 30 euthyroid controls (31-96, mean 63.7 +/- 18.4 years) screened for good general health. We evaluated attention, orientation, memory, learning, visual-spatial abilities, calculation, language, visual scanning, and motor speed using standardized neuropsychological tests. Electrophysiological measures of neurocognitive function included the P300 latency component of the auditory Event-Related Potentials (ERP) and conduction speed from eye to cortex, the P100 latency component of the Patterned Visual-Evoked Potential (PVEP). All patients were studied when hypothyroid. A subset of patients with minimal initial test abnormalities were available to be retested when euthyroid, 5 and 9 months after onset of thyroid replacement therapy. RESULTS Hypothyroid patients showed significantly lower scores on the Mini-Mental Status Test (MMS) and on five of 14 neuropsychological tests as compared to controls. The neuropsychological tests affected were copying a cube (visual-spatial function), the Inglis Paired Associates Learning Test-Low and Medium association items (memory and learning), Animal Naming (word fluency/production), and the Trail Making A test (attention, visual scanning and psychomotor function. Hypothyroidism also was associated with longer P100 latencies of PVEPs to 20' checks, but showed no significant differences in PVEP P100 latency to 50' checks, nor in the latency of the auditory ERP component P300. There was a statistically significant correlation between a laboratory index of the severity of hypothyroidism (serum T4) and the Inglis Medium Association items and Animal Naming. There was a statistically significant improvement after 5 months of treatment on three of the timed performance tests that previous studies have shown to be most sensitive to brain dysfunction. CONCLUSION Hypothyroidism in non-demented older adults is associated with impairments in learning, word fluency, visual-spatial abilities, and some aspect of attention, visual scanning, and motor speed. The MMS by itself was sensitive in differentiating hypothyroid patients with cognitive deficits from controls, while electrophysiological measures did not generally differentiate the hypothyroid patients from normal controls. The MMS was not sensitive to treatment effects, but treatment was associated with significant improvements in three of the most sensitive measures of cognitive dysfunction.
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Affiliation(s)
- D Osterweil
- Jewish Homes for the Aging, Reseda, CA 91335-3798
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Holder GE, Condon JR. Pattern visual evoked potentials and pattern electroretinograms in hypothyroidism. Doc Ophthalmol 1989; 73:127-31. [PMID: 2638622 DOI: 10.1007/bf00155030] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This study reports the pattern visual evoked potential (PVEP) findings in 10 patients with idiopathic hypothyroidism. Eight of these patients also had pattern electroretinography (PERG) performed and six were additionally seen after treatment with thyroxine. Only one patient had definitely abnormal PVEPs at the time of initial recording. PERGs at this time were of abnormal latency and subnormal amplitude. Following treatment with thyroxine the patient became euthyroid. Repeat electrodiagnostic testing now showed both PERGs and PVEPs within the normal range, having markedly improved in both latency and amplitude. This suggests that the PVEP delay was probably secondary to reversible central retinal dysfunction.
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Affiliation(s)
- G E Holder
- Department of Clinical Neurophysiology, Brook General Hospital, London, UK
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Sandford NL, Saul RE. Assessment of hepatic encephalopathy with visual evoked potentials compared with conventional methods. Hepatology 1988; 8:1094-8. [PMID: 3417229 DOI: 10.1002/hep.1840080519] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Thirty-six patients with advanced chronic liver disease of predominantly alcoholic etiology and with a documented history or current physical evidence of hepatic encephalopathy were studied and compared to 30 healthy controls. Assessment was made of their mental state, number connection test, venous blood ammonia, electroencephalography and visual evoked potentials with both pattern reversal and flash stimuli. Because of considerable inter- and intraindividual variation in waveform, visual evoked potentials from flash stimuli were considered unreliable. In pattern reversal visual evoked potentials, the latency of the N1 and P1 waves was significantly longer (p less than 0.05) in patients than in controls; however, the wave latencies did not correlate with the mental state score. The mental state score correlated with the number connection test (r = 0.69, p less than 0.001), asterixis (r = 0.36, p less than 0.05), electroencephalography mean dominant frequency (r = 0.44, p less than 0.01) and blood ammonia (r = 0.60, p less than 0.01). In 14 patients studied sequentially, change in the mental state score correlated with change in the number connection test (r = 0.80, p less than 0.01) and asterixis (r = 0.75, p less than 0.01) but not with change in the electroencephalography, blood ammonia or visual evoked potential wave latencies. Although visual evoked potentials are abnormal in patients with alcoholic cirrhosis and encephalopathy, they are less accurate in assessing the level of consciousness than simple bedside evaluation with a number connection test.
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Affiliation(s)
- N L Sandford
- Liver Unit, Rancho Los Amigos Medical Center, Downey, California 90242
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Abstract
Pattern reversal visual evoked potentials (VEPs) have been elicited in 16 female hyperthyroid patients before and after treatment and compared with those from a similar group of age and sex matched control subjects. No effect on latency was seen, and although larger amplitude values were noted in the thyrotoxic group these too were not significant. We would conclude that hyperthyroidism per se has little effect on the pattern reversal VEP, and any observed effect on these potentials is probably due to other factors.
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Affiliation(s)
- K W Mitchell
- University Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne
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Laureau E, Hebert R, Vanasse M, Letarte J, Glorieux J, Desjardins M, Dussault JH. Somatosensory evoked potentials and auditory brain-stem responses in congenital hypothyroidism. II. A cross-sectional study in childhood. Correlations with hormonal levels and developmental quotients. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1987; 67:521-30. [PMID: 2445544 DOI: 10.1016/0013-4694(87)90054-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We report the results of somatosensory evoked potentials (SEPs) and auditory brain-stem responses (ABRs) done in 48 congenital hypothyroid (CH) treated children, early detected and aged 18 months, 3 and 5-9 years of age. We report also the results of SEP and ABR done in 9 3-year-old CH children, before and after a 1 month therapy interruption to reassess the thyroid status. The more frequent abnormalities were increased wave I latencies for 18 month and 3-year-old CH children. In some children, these increases were not associated with signs of otitis media. No significant difference was seen between CH children and controls for SEP latencies and ABR and SEP interpeak latencies (IPLs). Similarly, no significant difference was seen between the two recording sessions in the 9 3-year-old CH children for ABR and SEP. On an individual basis, we observed abnormalities of central conduction time for ABR and SEP in several CH children. Moreover, significant partial correlations were found between ABR and SEP IPLs and thyroxine (T4) serum levels at diagnosis and thyrotropin (TSH) serum levels at the time of recording. There was also a significant partial correlation between N19-P22 IPLs and the practical reasoning scale of the Griffiths test considering the whole group of CH children. These results indicate that SEP might eventually be used to detect CH children at risk of presenting developmental abnormalities.
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Affiliation(s)
- E Laureau
- Laboratoire d'Electrophysiologie Médicale, Hôpital Sint-Justine, Université de Montréal, Que., Canada
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Laureau E, Vanasse M, Hebert R, Letarte J, Glorieux J, Desjardins M, Dussault JH. Somatosensory evoked potentials and auditory brain-stem responses in congenital hypothyroidism. I. A longitudinal study before and after treatment in six infants detected in the neonatal period. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1986; 64:501-10. [PMID: 2430772 DOI: 10.1016/0013-4694(86)90186-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report the results of a longitudinal study of auditory brain-stem responses (ABRs) and somatosensory evoked potentials (SEPs) performed in 6 children with congenital hypothyroidism. These infants were detected by the Quebec Network for Genetic Medicine and treated early. ABRs and SEPs were recorded both before and 2 weeks after the initiation of therapy and at 6 months of age. Before treatment, for SEP, we found increased wave N19, P22 latencies and N13-N19, N19-P22 interpeak latencies (IPLs) in congenital hypothyroid (CH) children. For ABR, there were increased wave I latencies with normal I-V IPLs. Substitutive therapy improved these abnormalities although this improvement was more evident after a shorter period of time for ABRs than for SEPs. Even at 6 months, 2 CH children still showed increased N13-N19 IPLs. Both had very low serum T4 levels at the time of diagnosis and one had also a very small knee surface area, both criteria indicating a severe hypothyroidism. It will be interesting to verify if initial and persisting increase of N13-N19 IPL is associated with later neuropsychological problems.
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