Right Homonymous Hemianopsia Of The Injured Brain Revealed With Functional Magnetic Resonance Imaging

Abstract

Abstract: : Purpose: The injured brain is sometimes silent on structural magnetic resonance imaging. Although our patients with brain injury have clear symptoms, we often cannot detect focal brain lesions with conventional structural magnetic resonance imaging. In this study, we used functional magnetic resonance imaging to detect left occipital inactivation, which could not be detected with structural magnetic resonance imaging or single–photon emission computed tomography. Methods: After sustaining a defuse brain injury a 55–year–old right–handed man complained of a disturbance in the left visual field and a feeling of darkness across the entire visual field. Goldmann perimetry showed left homonymous hemianopsia. However, no loss of visual acuity or funduscopic abnormalities were found. In addition, magnetic resonance imaging of the entire brain showed no conspicuous structural abnormalities. Single photon emission computed tomography showed decreased blood flow in the occipital lobes but no differences between the sides. The patient participated in an event–related functional magnetic resonance imaging experiment with a X–shaped black and white checkerboard as a visual stimulus shown for 1 second every 10 seconds. The patient was instructed to push a button once with the right hand whenever the color of the fixation point did not change and twice whenever it changed from gray to isoluminant red, which occurred randomly half the time. Results: Obvious activations were observed throughout the right occipital lobe, but no activation was observed in the left occipital lobe. Conclusions: Functional magnetic resonance imaging is useful for assessing residual cerebral function after a defuse brain injury.

Keywords: neuro–ophthalmology: cortical function/rehabilitation • visual cortex • visual fields