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Visual field defects after radiosurgery for mesial temporal lobe epilepsy
Author(s) -
HensleyJudge Holly,
Quigg Mark,
Barbaro Nicholas M.,
Newman Steven A.,
Ward Mariann M.,
Chang Edward F.,
Broshek Donna K.,
Lamborn Kathleen R.,
Laxer Kenneth D.,
Garcia Paul,
Heck Christianne N.,
Kondziolka Douglas,
Beach Robert,
Salanova Vicenta,
Goodman Robert
Publication year - 2013
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/epi.12215
Subject(s) - hippocampal sclerosis , visual field , temporal lobe , epilepsy surgery , medicine , optic radiation , radiosurgery , epilepsy , optic chiasm , surgery , psychology , anesthesia , optic nerve , radiology , ophthalmology , magnetic resonance imaging , radiation therapy , white matter , psychiatry
Summary Purpose Gamma knife radiosurgery ( RS ) may be an alternative to open surgery for mesial temporal lobe epilepsy ( MTLE ), but morbidities and the anticonvulsant mechanisms of RS are unclear. Examination of visual field defects ( VFDs ) after RS may provide evidence of the extent of a postoperative fixed lesion. VFDs occur in 52–100% of patients following open surgery for MTLE . Methods This multicenter prospective trial of RS enrolled patients with unilateral hippocampal sclerosis and concordant video–electroencephalography ( EEG ) findings. Patients were randomized to low (20 Gy) or high (24 Gy) doses delivered to the amygdala, hippocampal head, and parahippocampal gyrus. Postoperative perimetry were obtained at 24 months after RS . Visual field defect ratios ( VFDRs ) were calculated to quantify the degree of VFDs . Results were contrasted with age, RS dose and 50% isodose volume, peak volume of radiation‐induced change at the surgical target, quality of life measurements, and seizure remission. Key Findings No patients reported visual changes and no patients had abnormal bedside visual field examinations. Fifteen (62.5%) of 24 patients had postoperative VFDs , all homonymous superior quadrantanopsias. None of the VFD s were consistent with injury to the optic nerve or chiasm. Clinical diagnosis of VFD s correlated significantly with VFDRs (p = 0.0005). Patients with seizure remission had smaller (more severe) VFDRs (p = 0.04). No other variables had significant correlations. Significance VFD s appeared after RS in proportions similar to historical comparisons from open surgery for MTLE . The nature of VFD s was consistent with lesions of the optic radiations. The findings support the hypothesis that the mechanism of RS involves some degree of tissue damage and is not confined entirely to functional changes in neuromodulation.