Abstracts

Rationale: Visual memory is a generic term that refers to neuropsychological tasks created to measure nonverbal memory of information presented through the visual modality. Functional neuroimaging demonstrates that visual memory tested using abstract designs, faces and spatial locations primarily elicits right temporal lobe activation. We compared the rates of individual change in spatial, abstract design and facial memory after unilateral anterior temporal lobe resection (ATR), as well as evaluated the factors that predict individual change. Methods: The sample consisted of 83 individuals who underwent a standard ATR (47 right, 36 left) and were left-hemisphere language dominant. Visual memory tests included the Nonverbal Selective Reminding Test, Benton Visual Retention Test, Rey-Osterrieth Complex Figure Test and Warrington’s Recognition Memory Test for Faces. All patients completed at least two of the four tests. Results: We found significant decline in visual memory following right-ATR specific to the type of ability tested. There were declines found in memory of spatial locations following right-ATR versus left-ATR (38.6% versus 11.8%, post-hoc χ2=7.5, p=0.007) and in memory for faces (28.6% versus 6.3%, post-hoc χ2=3.8, p=0.05); however there was no between-group difference in memory for abstract designs. The major predictors of decline in memory for spatial locations were the side of surgery, better pre-surgical memory ability and poor post-surgical seizure control, χ2(7,N=76)=19.6, p=0.006. Instead of side of surgery, memory for abstract designs was vulnerable to decline in patients who had better abstract design memory prior to surgery, poor seizure control following surgery, and a shorter duration of illness, χ2(3,N=61)=15.0,p=0.002. Conclusions: The reasons for decline in visual memory after surgery are multi-factorial and specific to the type of visual memory ability tested. Even though the majority of patients showed either no change or significant improvements in visual memory following right-ATR, the risk for impairment is greater than following left-ATR and not negligible. Results provide rates of meaningful change to help clinicians and patients make better informed decisions about risks associated with undergoing right-ATR. Understanding what factors predict meaningful decline in visual memory can help to prepare patients at increased risk to understand the impairments that may occur after surgery.