Introduction to Cerebral Visual Impairment and Cerebral Palsy

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Introduction[edit | edit source]

Cerebral visual impairment (CVI) occurs in children with cerebral palsy (CP) or developmental delay. [1] Children with CVI have been frequently diagnosed with cerebral palsy. Despite the importance of early diagnosis, there is no standardised assessment tool to diagnose CVI and one referral criteria guideline. [1] The challenge in early diagnosis comprises a wide range of visual dysfunctions present in CVIs. They include central and peripheral vision dysfunction, dysfunctions in movement perception, gaze control, visual guidance of movement, visual attention, attentional orientation in space, visual analysis and recognition, visual memory and spatial cognition, which can affect a child's learning and social interactions. [2]This article presents an overview of CVI and its relationship with cerebral palsy.

Definitions[edit | edit source]

Cerebral Visual Impairment[edit | edit source]

Cerebral Visual Impairment (CVI) is “a verifiable visual dysfunction, which cannot be attributed to disorders of the anterior visual pathways or any potentially co-occurring ocular impairment.” [3]

Cerebral Palsy[edit | edit source]

Cerebral Palsy (CP) "describes a group of permanent disorders of the development of movement and posture causing activity limitation, which is attributed to non-progressive disturbances that occurred in the developing fetal or infant brain."[4]

Brain Involvement in Vision[edit | edit source]

"It is estimated that over 50% of the brain is involved in vision processing." [5] --Angela Kiger

The following example explains the process of the brain controlling the eyesight:

Example: the child plays the game of ball catching:[5][6][2]

  • The child sees the ball
  • The frontal lobe' of the brain decides about taking the action of ball catching and decides about its strategy.
  • The occipital lobe process the information received through the eyes. It passes the processed image data to the posterior parietal lobes via the superior longitudinal fasciculi.
  • The middle part of the temporal lobe supports this process, together with the posterior thalamus and superior colliculi, facilitating visual search and visual guidance of movement.
  • The ball is identified and chosen for the target.
  • The parietal lobe' gauges the distance between the child's hands and the ball. If this is not the child's first involvement in this game, the temporal lobe takes part in the process as it controls memory. It subconsciously reminds the child that their hands are used to catch the ball, that he needs to reach out, and that his body needs to adjust.
  • The temporal lobes via a bundle of nerve fibres on each side, process the local and detailed visual feedback.
  • The child involves his cerebellum to adjust his actions' timing and balance.

Epidemiology[edit | edit source]

  • CVI affect at least 3.4% of children. However, the number may be higher as many affected children go unidentified. [7]
  • More than 50% of children with learning difficulties who attend special schools have CVI. [7]
  • CVI is present in 2 per 1000 live births and 19 per 1000 live births for infants born at 20-27 weeks gestation, with subcortical damages being more common in preterms. [8][9]
  • Most common cause of permanent vision loss in children 1-3 years old.[5]
  • Almost 50% of the children diagnosed with a visual impairment have CVI. [5]
  • 56% of individuals with CVI have additional disabilities.  [5]

Aetiology[edit | edit source]

The aetiology of CVI in children can be either prenatal, perinatal or postnatal:[10]

Prenatal:

Perinatal:

Postnatal:

Brain Damage and CVI[edit | edit source]

The brain damage in patients with CVI can be categorised as subcortical, cortical or both.

Brain lesions resulting in CVI can affect the following parts of the brain:

  • the posterior visual pathways (the visual cortex of the occipital lobe)
  • the optic chiasm ("part of the brain where the optic nerves cross" [11])
  • lateral geniculate bodies (a structure in the thalamus)
  • optic radiations ("key white matter structures that cross the temporal lobe"[12])
  • primary visual cortices (part of the occipital lobe that processes visual information)
  • the middle temporal lobes
  • the visual association areas

The following video explains the role of the visual association areas.

The lack of vision tends to be profound when the thalamus is involved.

can occur in isolation or association with eye or optic nerve damage

Characteristics of CVI[edit | edit source]

The symptoms of CVI and the severity of visual impairment vary in children. They can affect the following:[10]

  • sensory visual function: it enables an individual "to be aware of colour, light level, contrast, motion and other visual stimuli".[13]
  • oculomotor function: "the ability to use the eyes systematically to efficiently scan and locate an object in the field of vision." [14]
  • visual-motor function: "integration between visual perception and motor skills."[15]
  • cognitive visual function: ability to analyse and process visual information. [16]

Assessment[edit | edit source]

questionnaires, functional vision assessment (CVI Range), neuropsychological tests of visual perception, and eye tracking. Eye tracking shows promise for visual assessment in both clinical and research settings because it is objective and quantitative, with the ability to assess diverse visual parameters.[17]

Resources[edit | edit source]

  • bulleted list
  • x

or

  1. numbered list
  2. x

References[edit | edit source]

  1. ↑ 1.0 1.1 Boonstra FN, Bosch DGM, Geldof CJA, Stellingwerf C, Porro G. The Multidisciplinary Guidelines for Diagnosis and Referral in Cerebral Visual Impairment. Front Hum Neurosci. 2022 Jun 30;16:727565.
  2. ↑ 2.0 2.1 Chokron S, Kovarski K, Dutton GN. Cortical Visual Impairments and Learning Disabilities. Front Hum Neurosci. 2021 Oct 13;15:713316.
  3. ↑ Sakki HEA, Dale NJ, Sargent J, Perez-Roche T, Bowman R. Is there consensus in defining childhood cerebral visual impairment? A systematic review of terminology and definitions. Br J Ophthalmol. 2018 Apr;102(4):424-432.
  4. ↑ Rosenbaum P, Paneth N, Leviton A, Goldstein M, Bax M, Damiano D, Dan B, Jacobsson B. A report: the definition and classification of cerebral palsy April 2006. Dev Med Child Neurol Suppl. 2007 Feb;109:8-14. Erratum in: Dev Med Child Neurol. 2007 Jun;49(6):480.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Kiger A. Cerebral Visual Impairment and Cerebral Palsy. Plus Course 2023.
  6. ↑ Debrowski A. How does the brain control eyesight? (2020) Available from https://www.allaboutvision.com/resources/part-of-the-brain-controls-vision/ [last access 26.11.2023]
  7. ↑ 7.0 7.1 Williams C, Pease A, Warnes P, Harrison S, Pilon F, Hyvarinen L, West S, Self J, Ferris J; CVI Prevalence Study Group. Cerebral visual impairment-related vision problems in primary school children: a cross-sectional survey. Dev Med Child Neurol. 2021 Jun;63(6):683-689.
  8. ↑ Robertson CM, Watt MJ, Dinu IA. Outcomes for the extremely premature infant: what is new? And where are we going? Pediatr Neurol. 2009 Mar;40(3):189-96.
  9. ↑ Hoyt CS, Fredrick DR. Cortically visually impaired children: a need for more study. Br J Ophthalmol. 1998 Nov;82(11):1225-6.
  10. ↑ 10.0 10.1 Kozeis N. Brain visual impairment in childhood: mini review. Hippokratia. 2010 Oct;14(4):249-51.
  11. ↑ Ireland AC, Carter IB. Neuroanatomy, Optic Chiasm. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542287 [last access 26.11.2023]
  12. ↑ Rodrigues EM, Isolan GR, Becker LG, Dini LI, Vaz MAS, Frigeri TM. Anatomy of the optic radiations from the white matter fibre dissection perspective: A literature review applied to practical anatomical dissection. Surg Neurol Int. 2022 Jul 22;13:309.
  13. ↑ How the Visual Sensory System Works - HandsOn OT. Available from https://handsonotrehab.com/visual-sensory-system/ [last access 26.11.2023]
  14. ↑ What Are Oculomotor Skills? (2022). Available from https://llatherapy.org/what-are-oculomotor-skills/ [last access 26.11.2023]
  15. ↑ Stevens A, Bernier R. Visual-Motor Function. In: Volkmar, F.R. (eds) Encyclopedia of Autism Spectrum Disorders. Springer, New York, NY.
  16. ↑ Fazzi E, Bova S, Giovenzana A, Signorini S, Uggetti C, Bianchi P. Cognitive visual dysfunctions in preterm children with periventricular leukomalacia. Dev Med Child Neurol. 2009 Dec;51(12):974-81.
  17. ↑ Chang M, Borchert M. Methods of visual assessment in children with cortical visual impairment. Current Opinion in Neurology, 2021; 34(1):p 89-96.
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