Recovery of Visual Field Defect via Corpus Callosum in a Patient with Cerebral Infarct

Abstract

Recovery mechanism of visual field defect in stroke patients has not been clearly elucidated. In this study, we report on a patient with a cerebral infarct who showed recovery of visual field defect via the corpus callosum, using diffusion tensor tractography (DTT) for optic radiation (OR). A 57-year-old male patient underwent conservative management for a cerebral infarct in the subcortical white matter of the right temporal lobe. Left homonymous hemianopsia was detected on the 2-week Humphrey visual field test. However, the patient showed improvement of hemianopsia with time; consequently, a left lower peripheral visual defect with the resolution of the upper and medial portions of the initial left hemianopia was observed on the 11-month Humphrey visual field test. Both 2-week and 11-month DTTs for the right OR showed a discontinuation between the right lateral geniculate nucleus (LGN) and the right OR. On 2-week DTT, the left OR was connected to the transcallosal fibres, and on 11-month DTT, these transcallosal fibres were elongated to the right primary visual cortex via the right posterior OR. The visual field defect in this patient appears to have recovered by the neural pathway originating from the left OR and terminating in the primary visual cortex via the transcallosal fibres and right distal OR. We believe that the results of this study may suggest one of the mechanisms for recovery of visual field defect following injury of OR in stroke patients.

Using Vision to Study Poststroke Recovery and Test Hypotheses About Neurorehabilitation

“…[16][17][18] Functional neuroimaging has also proved to be a powerful tool for studying poststroke motor and language recovery. In fact, previous studies have detected similar types of plastic changes in the visual, motor, and language systems: (1) increased perilesional activation, 7,16,20 (2) perilesional cortical reorganization, 18,[21][22][23] (3) strengthening of existing corticocortical connections, [24][25][26][27][28] and (4) recruitment of distant brain regions. 16,[29][30][31][32][33] Given these similarities, a greater understanding of poststroke plastic changes in the visual pathway may shed light on recovery in the motor and language domains.…”

Diffusion Tensor Imaging Studies on Recovery of Injured Optic Radiation: A Minireview

“…Among those parameters, increments in FA or FV values and/or a decrement in the ADC value on follow-up DTI scans of an injured OR suggest that the injured OR is undergoing recovery. Three methods employed to determine the presence of recovery of an injured OR have been described in previous studies: (1) detection of visual changes on the color maps of follow-up DTIs; (2) detection of changes in the FA value measured in a specific region of interest (ROI) of an injured OR; and (3) detection of changes in the FN value and in three-dimensionally reconstructed configurations on follow-up DTTs [16][17][18][19][20][21][22][23][24] (Figure 2). However, the method used to detect changes to an injured OR visually on DTI color maps can be subjective, and the ROI-based method can yield false results due to interanalyzer variability in the assigning of ROI location [27].…”

“…In addition, on 2-week postonset DTT, the left OR was shown to be connected to the transcallosal fibers, and on 11month DTT, these transcallosal fibers appeared to have elongated to the right primary visual cortex via the right posterior OR. The authors suggested that the visual field defect in this patient had recovered via the recovery of the OR injury by way of the transcallosal fibers of the splenium of the corpus callosum [21,35]. However, this was a single case report and DTT for the OR was reconstructed using a deterministic algorithm [27][28][29][30].…”

“…In this minireview, DTI studies that have demonstrated recovery of OR injuries are reviewed [16][17][18][19][20][21][22][23][24]. Relevant studies in the period from 1992 to 2019 were identified by searching the following electronic databases: PubMed, Google Scholar, and MEDLINE.…”

“…In 2015, Jang and Lee, by using follow-up DTTs (DTI: 1.5T Philips Gyroscan Intera (Hoffman-La Roche, Best, the Netherlands) with single-shot EPI, navigator echo, and reconstruction conditions: anisotropy threshold of 0.2) of the OR, reported on a 57-year-old patient with a cerebral infarct in the right temporal lobe who showed recovery of the associated visual field defect via the transcallosal fibers of the corpus callosum [21]. Left-side homonymous hemianopsia was detected on a 2-week postonset visual field test; however, recovery of the left lower peripheral visual defect along with recovery of the upper and medial portions of the initial left hemianopia was observed on the 11-month postonset visual field test results.…”