DOCSLIB.ORG

Brain Imaging in a Patient with Hemimicropsia

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Brain Imaging in a Patient with Hemimicropsia View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by University of Regensburg Publication Server Neuropsychologia 37 (1999) 1327±1334 www.elsevier.com/locate/neuropsychologia Brain imaging in a patient with hemimicropsia J. Kassubek*, M. Otte, T. Wolter, M.W. Greenlee, T. Mergner, C.H. LuÈ cking Neurologische UniversitaÈtsklinik, UniversitaÈt Freiburg, Freiburg, Germany Received 8 June 1998; accepted 2 March 1999 Abstract Hemimicropsia is an isolated misperception of the size of objects in one hemi®eld (objects appear smaller) which is, as a phenomenon of central origin, very infrequently reported in literature. We present a case of hemimicropsia as a selective de®cit of size and distance perception in the left hemi®eld without hemianopsia caused by a cavernous angioma with hemorrhage in the right occipitotemporal area. The symptom occurred only intermittently and was considered the consequence of a local irritation by the hemorrhage. Imaging data including a volume-rendering MR data set of the patient's brain were transformed to the 3-D stereotactic grid system by Talairach and warped to a novel digital 3-D brain atlas. Imaging analysis included functional MRI (fMRI) to analyse the patient's visual cortex areas (mainly V5) in relation to the localization of the hemangioma to establish physiological landmarks with respect to visual stimulation. The lesion was localized in the peripheral visual association cortex, Brodmann area (BA) 19, adjacent to BA 37, both of which are part of the occipitotemporal visual pathway. Additional psychophysical measurements revealed an elevated threshold for perceiving coherent motion. which we relate to a partial loss of function in V5, a region adjacent to the cavernoma. In our study, we localized for the ®rst time a cerebral lesion causing micropsia by digital mapping in Talairach space using a 3-D brain atlas and topologically related it to fMRI data for visual motion. The localization of the brain lesion aecting BA 19 and the occipitotemporal visual pathway is discussed with respect to experimental and case report ®ndings about the neural basis of object size perception. # 1999 Elsevier Science Ltd. All rights reserved. Keywords: Micropsia; Size constancy; Cavernoma; Brain atlas; Functional MRI 1. Introduction distortions in the size or the shape of the perceived object, respectively. In dysmetropsia, objects may Hemianopic defects in vision are frequent phenom- appear either reduced (micropsia) or enlarged (macrop- ena in the daily neuro-ophthalmological clinical rou- sia) relative to their normal size. Micropsia is more fre- tine. Less common are complaints about more quently reported than macropsia, but both are rather complex changes in visual perception following lesions infrequent phenomena, even more so if occurring as of the cerebral cortex. These de®cits are of interest isolated symptoms. More common is the combination since they can shed light on the functional role of the of these perceptual abnormalities with visual ®eld loss lesioned cortical area. Examples are dysmetropsia (also following extensive central lesions [11]). called dysmegalopsia) and metamorphopsia, which The phenomenon of metamorphopsia appears to be re¯ect disorders of visual processing causing subjective related to the perceptual mechanism of size constancy (phenomenologically, an object appears to retain its size despite substantial variations in viewing distance). * Corresponding author. Neurologische Klinik und Poliklinik der Normally, the perceived size of an image is scaled UniversitaÈ t Freiburg, Breisacher Str. 64 79106, Freiburg, Germany. Tel.: +49-761-2705001 (work); fax: +49-0761-5559588. according to its perceived distance, depending on a E-mail address: [email protected] (J. Kassubek) number of depth and distance cues. Errors of scaling 0028-3932/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S0028-3932(99)00041-X 1328 J. Kassubek et al. / Neuropsychologia 37 (1999) 1327±1334 may occur with abnormalities in retinal image size, dis- 2. Clinical data turbances related to the binocular disparity and the central interpretation of the received aerent inputs. The patient was a 35-year-old right-handed male In cases where dysmetropsia occurs monocularly, it with no history of neurological disorders in his past. is likely to be due to retinal diseases which cause dis- As the ®rst clinical symptom, he reported an incident placement of the receptor cells, for instance excessive where he found himself lying on the ¯oor of his home separation of the photoreceptors by edematous ¯uid after falling down. Subsequently he suered from (like in central serous retinopathy; see [12]). severe occipital headache, but showed no focal neuro- Furthermore, dysmetropsia can result from a size re- logical de®cits. A cranial computed tomography duction of the retinal image due to an accommodation (CCT) in hospital showed a hyperdense lesion in his increase of the lens in¯uenced by the distances between right occipital lobe, suggestive of a hemangioma or the object plane and the pupil and the accommodation cavernoma. Since his headache disappeared within a level, which is a phenomenon called accommodative few days, the patient did not consent to further diag- micropsia [24]. A similar mechanism may underly the nostic measures. Six weeks later, a second episode of cases in which dysmetropsia occurs associated with acute headache occurred. This time the patient noticed muscular diseases such as ocular myasthenia [14]. In a change in visual perception, by experiencing transient cases of central origin, micropsia is mostly described episodes of dysmetropsia in the left hemi®eld; he saw as a transient phenomenon, occurring as prodroma of, objects on his left smaller, shrunk and compressed and or simultaneously with, temporal lobe epileptic seizures apparently farther away, though not distorted in or migraine [21]. It is then either accompanied by var- shape. Due to the hemimicropsia, he had diculties in ious symptoms of temporal lobe epilepsy, or it pre- perceiving proportions, symmetry, and depth, and, as sentsÐvery rarelyÐas a form of misperception a consequence, he collided with the left side of the gar- amongst others (metamorphopsia, dyschromatopsia) in age when parking his car. Interestingly, objects extend- purely visual seizures. Cases are reported in which ing into both hemi®elds appeared to be spatially micropsia was classi®ed as a psychopathological disparate, with the left half farther away. He had no phenomenon without evidence of neurological dysfunc- diculties in recognizing objects or persons and did tion (`psychogenic micropsia') [20], but these cases may not fail to comprehend the meaning of complex pic- possibly re¯ect undetected visual seizures. tures, as has been described in association with micro- There are only few reports in which micropsia (or psia [15]. Further episodes lasted from 30 min to 2 h hemimicropsia, i.e., apparent reduction of the size of in the following days, sometimes (but not always) ac- objects when presented in one hemi®eld) have been companied by headache. brought in association with a focal cerebral lesion, for In a conventional MRI investigation, the diagnosis instance a brain tumor, hemorrhage or ischaemic cavernous angioma was suggested by a peripheral low infarction. However, the lesions reported are rather signal ring (hemoglobin), 18 mm in diameter, and a scattered over extended regions of the brain, such as heterogeneous central signal (vascular malformation) the occipital lobe (micropsia associated with a homon- on T1-weighted images. The hemorrhage surrounding ymous loss of the visual ®eld) [12], the retrosplenial the cavernoma was accentuated at its superior and area [6], the chiasm [1] and visual association areas [3]. posterior parts, reaching well into the gray matter. It Wieser found micropsia/macropsia mainly when stimu- was diagnosed as a cavernous hemangioma with signs lating neocortical regions in the temporal-occipital bor- of a chronic bleeding (for details, see below). der zone [32]. A clearcut localization of a cortical area The frequency of micropsia episodes spontaneously for size constancy remains undetermined to date. The decreased to once or twice a week in the following results of work in monkeys suggest that size perception months, during which the patient did not seek out is mainly dependent on the occipito-temporal stream further medical treatment. Four months after the ®rst of visual information [19,28]. occurrence, the frequency and duration of the micro- We present here the case of a 35-year-old patient psia episodes increased anew and the patient was with recurrent hemimicropsia in the left hemi®eld admitted to our hospital. Clinical-neurological examin- resulting from a cavernous angioma in the right occipi- ation revealed no objective de®cit. A follow-up MRI tal lobe. After neurosurgical removal of the angioma, showed constant ®ndings with respect to the caver- the misperception no longer occurred. Exact localiz- noma. Both MR angiography and cerebral catheter ation data were gathered by magnetic resonance ima- angiography were normal, in line with the diagnosis ging and computer-guided reconstruction techniques cavernous angioma. Electroencephalography (EEG), and were related to the clinical and behavioural ®nd- consisting of a standard clinical protocol with 12 scalp ings. Functional MRI (fMRI) was employed to electrodes placed according to the International
Load more

Recommended publications
  • Care of the Patient with Accommodative and Vergence Dysfunction
    OPTOMETRIC CLINICAL PRACTICE GUIDELINE Care of the Patient with Accommodative and Vergence Dysfunction OPTOMETRY: THE PRIMARY EYE CARE PROFESSION Doctors of optometry are independent primary health care providers who examine, diagnose, treat, and manage diseases and disorders of the visual system, the eye, and associated structures as well as diagnose related systemic conditions. Optometrists provide more than two-thirds of the primary eye care services in the United States. They are more widely distributed geographically than other eye care providers and are readily accessible for the delivery of eye and vision care services. There are approximately 36,000 full-time-equivalent doctors of optometry currently in practice in the United States. Optometrists practice in more than 6,500 communities across the United States, serving as the sole primary eye care providers in more than 3,500 communities. The mission of the profession of optometry is to fulfill the vision and eye care needs of the public through clinical care, research, and education, all of which enhance the quality of life. OPTOMETRIC CLINICAL PRACTICE GUIDELINE CARE OF THE PATIENT WITH ACCOMMODATIVE AND VERGENCE DYSFUNCTION Reference Guide for Clinicians Prepared by the American Optometric Association Consensus Panel on Care of the Patient with Accommodative and Vergence Dysfunction: Jeffrey S. Cooper, M.S., O.D., Principal Author Carole R. Burns, O.D. Susan A. Cotter, O.D. Kent M. Daum, O.D., Ph.D. John R. Griffin, M.S., O.D. Mitchell M. Scheiman, O.D. Revised by: Jeffrey S. Cooper, M.S., O.D. December 2010 Reviewed by the AOA Clinical Guidelines Coordinating Committee: David A.
    [Show full text]
  • Handbook of EEG INTERPRETATION This Page Intentionally Left Blank Handbook of EEG INTERPRETATION
    Handbook of EEG INTERPRETATION This page intentionally left blank Handbook of EEG INTERPRETATION William O. Tatum, IV, DO Section Chief, Department of Neurology, Tampa General Hospital Clinical Professor, Department of Neurology, University of South Florida Tampa, Florida Aatif M. Husain, MD Associate Professor, Department of Medicine (Neurology), Duke University Medical Center Director, Neurodiagnostic Center, Veterans Affairs Medical Center Durham, North Carolina Selim R. Benbadis, MD Director, Comprehensive Epilepsy Program, Tampa General Hospital Professor, Departments of Neurology and Neurosurgery, University of South Florida Tampa, Florida Peter W. Kaplan, MB, FRCP Director, Epilepsy and EEG, Johns Hopkins Bayview Medical Center Professor, Department of Neurology, Johns Hopkins University School of Medicine Baltimore, Maryland Acquisitions Editor: R. Craig Percy Developmental Editor: Richard Johnson Cover Designer: Steve Pisano Indexer: Joann Woy Compositor: Patricia Wallenburg Printer: Victor Graphics Visit our website at www.demosmedpub.com © 2008 Demos Medical Publishing, LLC. All rights reserved. This book is pro- tected by copyright. No part of it may be reproduced, stored in a retrieval sys- tem, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Library of Congress Cataloging-in-Publication Data Handbook of EEG interpretation / William O. Tatum IV ... [et al.]. p. ; cm. Includes bibliographical references and index. ISBN-13: 978-1-933864-11-2 (pbk. : alk. paper) ISBN-10: 1-933864-11-7 (pbk. : alk. paper) 1. Electroencephalography—Handbooks, manuals, etc. I. Tatum, William O. [DNLM: 1. Electroencephalography—methods—Handbooks. WL 39 H23657 2007] RC386.6.E43H36 2007 616.8'047547—dc22 2007022376 Medicine is an ever-changing science undergoing continual development.
    [Show full text]
  • After-Imagery in Defective Fields of Vision* by Morris B
    J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.12.3.196 on 1 August 1949. Downloaded from J. Neurol. Neurosurg. Psychiat., 1949, 12, 196. AFTER-IMAGERY IN DEFECTIVE FIELDS OF VISION* BY MORRIS B. BENDER and ROBERT L. KAHN From the Department of Neurology, New York University College ofMedicine, and Neurologic Services of the Mount Sinai Hospital and Bellevue Psychiatric Hospital In a study of visual after-images of patients with "bizarre" visual disturbances. There was a long- homonymous hemianopia one would anticipate standing history of hypertension and arteriosclerotic an after-image only in that part of the field which cardiovascular disease. His average blood pressure during the illness was 200/120 mm. Hg. A bilateral is perceived by the patient during fixation. Fuchs sympathectomy for relief of hypertension had been (1920, 1921), however, found that such patients saw perPormed in 1945. During the course of his long illness more in the after-image than in the stimulus field or he had symptoms and signs of embolization to the lungs, the perceived field of vision. Thus Fuchs noted kidneys, popliteal artery, and brain. that a figure only partly seen on fixation (the The cerebral infarcts which first occurred in 1942 were remainder of the figure was not seen because it was clinically localized to the occipital lobes. The visualguest. Protected by copyright. situated in the blind part of the field) was perceived symptoms consisted of-episodes of blurring of vision to by the same patient in its entirety in the after- the left of his fixation point, spells of momentary blind- image.
    [Show full text]
  • The Moon Illusion Explained Introduction and Summary
    The Moon Illusion Explained Finally! Why the Moon Looks Big at the Horizon and Smaller When Higher Up. Don McCready Professor Emeritus, Psychology Department University of Wisconsin-Whitewater Whitewater, WI 53190 Email to: mccreadd at uww.edu Introduction and Summary [Revised 12/07/02] For many centuries, scientists have been puzzled by the illusion that the full moon at the horizon usually looks larger than it does later, at higher elevations toward the zenith of the sky. Many explanations (theories) have been offered. But, it is fair to say that the two dozen (or so) scientists most familiar with current research on the illusion have not yet accepted any one theory. The jury is still out. The theory reviewed in this article is relatively quite new (McCready, 1983, 1985, 1986). It begins with the basic assumption that, when most people say "the moon looks larger," they are referring primarily to the moon's angular subtense (McCready, 1965). That is, the horizon moon looks a larger angular size than the zenith moon. That experience is imitated if you look at the circles in the figure at the right, because the lower circle subtends a larger angle at your eye than the upper circle does. Angular Size Illusion. For the moon, that appearance is known as the moon illusion, because the angle the moon's diameter subtends at your eye measures about 1⁄2 degree of arc no matter where the moon is in the sky. That is, there is no physical (optical) reason why the horizon moon should look larger than the zenith moon: For instance, it has been known for centuries that the horizon moon is not "magnified' by the earth's atmosphere.
    [Show full text]
  • Visual Perceptual Abnormalities: Hallucinations and Illusions John W
    SEMINARS IN NEUROLOGY—VOLUME 20, NO. 1 2000 Visual Perceptual Abnormalities: Hallucinations and Illusions John W. Norton, M.D.* and James J. Corbett, M.D.‡,§ ABSTRACT Visual perceptual abnormalities may be caused by diverse etiologies which span the fields of psychiatry and neurology. This article reviews the differential diagnosis of visual perceptual abnormalities from both a neurological and a psychiatric perspec- tive. Psychiatric etiologies include mania, depression, substance dependence, and schizophrenia. Common neurological causes include migraine, epilepsy, delirium, dementia, tumor, and stroke. The phenomena of palinopsia, oscillopsia, dysmetrop- sia, and polyopia among others are also reviewed. A systematic approach to the many causes of illusions and hallucinations may help to achieve an accurate diag- nosis, and a more focused evaluation and treatment plan for patients who develop visual perceptual abnormalities. This article provides the practicing neurologist with a practical understanding and approach to patients with these clinical symptoms. Keywords: Illusion, hallucination, perceptual abnormalities, oscillopsia, polyopia, diplopia, palinopsia, dysmetropsia, visual allesthesia, visual synthesia, visual dyses- thesia, sensation of environmental tilt, psychiatric, neurological The topic of visual perceptual abnormalities, spe- enable the clinician to understand the phenomenology cifically hallucinations and illusions, spans many fields while diagnosing and treating patients who present with of medicine. The most prominent among these are neu- these problems. rology, ophthalmology, and psychiatry. A wide variety of An illusion is the misperception of a stimulus that is pathological processes can lead to perceptual abnormali- present in the external environment.1 An example is ties. The purpose of this presentation is to review the when an elderly demented individual interprets a chair in neurological and psychiatric differential diagnoses of vi- a poorly lit room as a person.
    [Show full text]
  • A Shrunken World – Micropsia After a Right Occipito-Parietal Ischemic Stroke Nils S
    UvA-DARE (Digital Academic Repository) A shrunken world - micropsia after a right occipito-parietal ischemic stroke Van Den Berg, N.S.; Huitema, R.B.; Spikman, J.M.; Van Laar, P.J.; De Haan, E.H.F. DOI 10.1080/13554794.2019.1656751 Publication date 2019 Document Version Final published version Published in Neurocase License CC BY-NC-ND Link to publication Citation for published version (APA): Van Den Berg, N. S., Huitema, R. B., Spikman, J. M., Van Laar, P. J., & De Haan, E. H. F. (2019). A shrunken world - micropsia after a right occipito-parietal ischemic stroke. Neurocase, 25(5), 202-208. https://doi.org/10.1080/13554794.2019.1656751 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:27 Sep 2021 NEUROCASE 2019, VOL.
    [Show full text]
  • Book XVII License and the Law Editor: Ramon F
    8 88 8 8nd 8 8888on.com 8888 Basic Photography in 180 Days Book XVII License and the Law Editor: Ramon F. aeroramon.com Contents 1 Day 1 1 1.1 Photography and the law ....................................... 1 1.1.1 United Kingdom ....................................... 2 1.1.2 United States ......................................... 6 1.1.3 Hong Kong .......................................... 8 1.1.4 Hungary ............................................ 8 1.1.5 Macau ............................................. 8 1.1.6 South Africa ......................................... 8 1.1.7 Sudan and South Sudan .................................... 9 1.1.8 India .............................................. 10 1.1.9 Iceland ............................................ 10 1.1.10 Spain ............................................. 10 1.1.11 Mexico ............................................ 10 1.1.12 See also ............................................ 10 1.1.13 Notes ............................................. 10 1.1.14 References .......................................... 10 1.1.15 External links ......................................... 12 2 Day 2 13 2.1 Observation .............................................. 13 2.1.1 Observation in science .................................... 14 2.1.2 Observational paradoxes ................................... 14 2.1.3 Biases ............................................. 15 2.1.4 Observations in philosophy .................................. 16 2.1.5 See also ...........................................
    [Show full text]
  • Neuropsychiatry Review Series: Disorders of Visual Perception. Dominic Ffytche, Jan Dirk Blom, Marco Catani
    Neuropsychiatry Review series: Disorders of Visual perception. Dominic Ffytche, Jan Dirk Blom, Marco Catani To cite this version: Dominic Ffytche, Jan Dirk Blom, Marco Catani. Neuropsychiatry Review series: Disorders of Visual perception.. Journal of Neurology, Neurosurgery and Psychiatry, BMJ Publishing Group, 2010, 81 (11), pp.1280. 10.1136/jnnp.2008.171348. hal-00587980 HAL Id: hal-00587980 https://hal.archives-ouvertes.fr/hal-00587980 Submitted on 22 Apr 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Disorders of visual perception Dr Dominic H ffytche1,4* Dr JD Blom2,3 4 Dr M Catani 1 Department of Old Age Psychiatry, Institute of Psychiatry, King’s College London, UK 2 Parnassia Bavo Group, The Hague, the Netherlands 3 Department of Psychiatry, University of Groningen, Groningen, the Netherlands 4 Natbrainlab, Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, King’s College London, UK *Address for Correspondence Dr D H ffytche Department of Old Age Psychiatry, Institute of Psychiatry PO70, King’s College
    [Show full text]
  • Palinopsia As a Rare Presenting Symptom of Occipital Stroke “Case Report”
    Case Reports in Clinical Medicine, 2021, 10, 203-212 https://www.scirp.org/journal/crcm ISSN Online: 2325-7083 ISSN Print: 2325-7075 Palinopsia as a Rare Presenting Symptom of Occipital Stroke “Case Report” Muaz Abdellatif Elsayed*, Mohamed Atif Makdum, Sheena Shirmilon Salim, Nuzrath Salmin Abdul Razak University Hospital Sharjah, Sharjah, UAE How to cite this paper: Elsayed, M.A., Abstract Makdum, M.A., Salim, S.S. and Razak, N.S.A. (2021) Palinopsia as a Rare Present- Palinopsia is the recurrence or persistence of visual images after cessation of ing Symptom of Occipital Stroke “Case the stimulus. Palinopsia has been associated with a wide variety of etiologies Report”. Case Reports in Clinical Medicine, and mechanisms such as drug induced, seizures, migraine, psychiatric condi- 10, 203-212. https://doi.org/10.4236/crcm.2021.107026 tions, head trauma and structural lesions in the brain. We report a case of oc- cipital stroke who presented with oscillating palinopsia. Sudden-onset pali- Received: June 16, 2021 nopsia is a very rare symptom of stroke, but it must be recognized early as it Accepted: July 19, 2021 is a highly time dependent, and potentially treatable condition. A 57-year-old Published: July 22, 2021 woman with a history of poorly controlled type 2 diabetes, hyperlipidemia, Copyright © 2021 by author(s) and and hypertension presented with sudden onset right sided palinopsia with Scientific Research Publishing Inc. images of her face and right forearm with hand, occurring several times in a This work is licensed under the Creative day, lasting for a few minutes each time, and appearing in the same location Commons Attribution International License (CC BY 4.0).
    [Show full text]
  • Review Article Alice in Wonderland Syndrome: a Clinical and Pathophysiological Review
    Hindawi Publishing Corporation BioMed Research International Volume 2016, Article ID 8243145, 10 pages http://dx.doi.org/10.1155/2016/8243145 Review Article Alice in Wonderland Syndrome: A Clinical and Pathophysiological Review Giulio Mastria,1 Valentina Mancini,1 Alessandro Viganò,1,2 and Vittorio Di Piero1,3 1 DepartmentofNeurologyandPsychiatry,SapienzaUniversityofRome,Rome,Italy 2Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Sapienza University of Rome, Rome, Italy 3University Consortium for Adaptive Disorders and Head Pain (UCADH), Pavia, Italy Correspondence should be addressed to Alessandro Vigano;` [email protected] Received 13 June 2016; Accepted 20 November 2016 Academic Editor: Oliver von Bohlen und Halbach Copyright © 2016 Giulio Mastria et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Alice in Wonderland Syndrome (AIWS) is a perceptual disorder, principally involving visual and somesthetic integration, firstly reported by Todd, on the literary suggestion of the strange experiences described by Lewis Carroll in Alice in Wonderland books. Symptoms may comprise among others aschematia and dysmetropsia. This syndrome has many different etiologies; however EBV infection is the most common cause in children, while migraine affects more commonly adults. Many data support a strict relationship between migraine and AIWS, which could be considered in many patients as an aura or a migraine equivalent, particularly in children. Nevertheless, AIWS seems to have anatomical correlates. According to neuroimaging, temporoparietal- occipital carrefour (TPO-C) is a key region for developing many of AIWS symptoms. The final part of this review aims to find the relationship between AIWS symptoms, presenting a pathophysiological model.
    [Show full text]
  • Potential Role of Müller Cells in the Pathogenesis of Macropsia Associated with Epiretinal Membrane: a Hypothesis Revisited
    Int J Ophthalmol, Vol. 10, No. 11, Nov.18, 2017 www.ijo.cn Tel:8629-82245172 8629-82210956 Email:[email protected] ·Hypothesis· Potential role of Müller cells in the pathogenesis of macropsia associated with epiretinal membrane: a hypothesis revisited Ahmet Colakoglu1, Solmaz Balci Akar2 1Department of Ophthalmology, Acibadem University School understood[2]. Even with the development of adaptive optics of Medicine, Istanbul 34752, Turkey imaging technologies, proof has yet to be discovered that a 2Department of Ophthalmology, Istanbul University Cerrahpasa higher cone packing density from cone compression occurs School of Medicine, Istanbul 34098, Turkey in subjects with retinal induced macropsia. Therefore, we Correspondence to: Ahmet Colakoglu. Department of examined an alternative hypothesis to explain the mechanisms Ophthalmology, Acibadem University School of Medicine, of retinal induced macropsia. Istanbul 34752, Turkey. [email protected] Kim et al[3] concluded that the development of metamorphopsia Received: 2016-07-18 Accepted: 2017-06-13 is a complex process and that central visual perception processes may play a role. However, our PubMed literature Abstract search did not identify any evidence of central nervous system ● Pathophysiological explanations for metamorphopsia involvement in eyes with epiretinal membrane (ERM). associated with retinal pathologies generally focus on Therefore, it is more likely that central processes only play a photoreceptor organization disruption. However, the retinal negligible role and that retinal processes are largely responsible microarchitecture is complicated, and we hypothesize that for the development of macropsia. The most common cause other retinal cells may also be involved. Metamorphopsia of macropsia is ERM formation[4] and a common complaint in has been widely studied in eyes with epiretinal membranes ERM patients is metamorphopsia[5-6].
    [Show full text]
  • The Near Triad and Associated Visual Problems†
    S Afr Optom 2007 66(4) 184-191 STUDENT ARTICLE The near triad and associated visual problems† R Emslie*, A Claassens*, N Sachs* and I Walters* Department of Optometry, University of Johannesburg, Auckland Park Campus, PO Box 524, Auckland Park, Johannesburg, 2006 South Africa <[email protected]> When a person changes fixation from one target, at a given fixation distance, to another target, at an alternate fixation distance, a number of ocular systems need to be altered in order to maintain clear single binocular vision. One such system is that of accommodation, involving either positive or negative accommodation1. When viewing an object at six meters, a distance known optometrically as optical infinity, it is assumed that parallel light rays enter the eye. For an emmetrope this results in zero accommodative demand and therefore zero accommodation. When viewing an object closer than 6 meters positive accommodation is required. This involves intraocular lens changes which ultimately increase the refractive power of the eye, allowing the rays to form a point focus on the retina. The opposite process, negative accommodation, occurs when an object is fixated further away from some near fixation point. Accommodation can therefore be thought of as the process by which the refractive power of the eye is altered to ensure a clear retinal image1. It should also be noted that a change in the position of the visual axes must also take place1. This occurs to ensure that a single image of the target is seen. The change in relative position of the visual axis is called convergence when the angle formed by the visual axes increases, and divergence when this angle decreases1.
    [Show full text]