RESUMEN
The relations between brain areas involved in vision were explored in 8 patients with unilateral acute optic neuritis using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). In all patients monocular stimulation of affected and unaffected eye elicited significantly different activation foci in the primary visual cortex (V1), whereas the foci evoked in the middle temporal visual area (area V5) were similar in size and in delay of blood-oxygen-level-dependent response. DTI analysis documented lower white matter anisotropy values and reduced fibre reconstruction in the affected compared with the unaffected optic nerves. The preserved activation of area V5 observed in all our patients is an interesting finding that suggests the notion of a different sensitivity of the optic pathways to inflammatory changes.
RESUMEN
To study the functional recovery of a patient with cerebrovascular injury using combined functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI). A 24-year-old woman with left hemianopsia underwent fMRI and DTI in a 1.5-tesla machine both in the acute phase and 1 month after an ischaemic stroke involving the right calcarine cortex. Acute-phase fMRI demonstrated that peripheral left visual field stimulation did not activate the right primary visual cortex, whereas stimulation 1 month later activated the visual cortex bilaterally. Analysis of acute-phase DTI data disclosed that a reduction of fractional anisotropy in the right optic radiation had almost resolved after 1 month. Fibre direction was normal at either time point. fMRI and DTI can demonstrate functional damage and recovery in patients with neuro-ophthalmological lesions.