“Hemispheric asymmetry in the Meyer's Loop” – a prospective study of visual field deficits in 105 cases undergoing anterior temporal lobe resection for epilepsy

Noor Ul Owase Jeelani (1) , Panitha Jindahra (2) , Mandeep S Tamber (3) , Tak Lap Poon (4) , Paul Kabasele (2) , Merle James-Galton (5) , John Stevens (5) , John Duncan (5) , Andrew W Mcevoy (5) , William Harkness (1) , Gordon T Plant (5)

1 GOSH - Great Ormond Street Hospital for Children [London]
2 Department of Clinical and Experimental Epilepsy
3 SickKids - The Hospital for sick children [Toronto]
4 Queen Elizabeth Hospital
5 The National Hospital For Neurology and Neurosurgery

Objectives Visual field deficits following temporal lobe surgery have been reported in the literature. In this prospective study, we analyse our experience of visual field deficits in 105 cases undergoing temporal lobe surgery by a single surgeon with particular consideration of the laterality of the deficit and its functional implications. Methods 105 consecutive patients undergoing an anterior temporal lobe resection for epilepsy, between March 1998 and June 2004 were selected. Pre and post-operative visual field tests were obtained using the Humphrey Esterman binocular functional test for all cases. Post-operative MRI scans were carried out on all patients. 60 scans were randomly selected and the extent of temporal lobe resection calculated manually for each. Results Of the 105 cases, 16 patients had a visual field deficit post operatively which was not present pre operatively; 12 following a left and 4 following a right-sided resection. The Odds Ratio for incurring a postoperative visual field defect following left vs. right-sided surgery was 3.51 (95% CI 1.05-11.73, p=0.04). In 4 patients the deficit was severe enough to preclude them from driving in the UK (3 left and 1 right sided resection). There was no association between the extent of tissue resection and the incidence of post-operative visual field deficits. Conclusions This study suggests left / right hemispheric asymmetry in the Geniculocalcarine tracts with field deficits being 3.5 times more likely following left sided anterior temporal lobe resections compared with right sided resections. This has significant implications on counselling patients for these procedures.

Mots clés: ANATOMY; EPILEPSY; SURGERY; VISION

Noor Ul Owase Jeelani, Panitha Jindahra, Mandeep S Tamber, Tak Lap Poon, Paul Kabasele, et al.. “Hemispheric asymmetry in the Meyer's Loop” – a prospective study of visual field deficits in 105 cases undergoing anterior temporal lobe resection for epilepsy. Journal of Neurology, Neurosurgery and Psychiatry, 2010, 81 (9), pp.985. ⟨10.1136/jnnp.2009.182378⟩. ⟨hal-00557406⟩