Temporal lobectomy is an effective therapy for medically refractory temporal lobe epilepsy (TLE), but may be complicated by amnestic syndromes. Therefore, pre-surgical evaluation to assess the risk/benefit ratio for surgery is required. Intracarotid amobarbital testing (IAT) is currently the most widely used method for assessing pre-surgical memory lateralization, but is relatively invasive. Over the past decade functional MRI (fMRI) has been shown to correlate with IAT for language lateralization, and also for memory lateralization in a small number of patients. This study was carried out to compare fMRI during memory encoding with IAT testing for memory lateralization, and to assess the predictive value of fMRI during memory encoding for post-surgical memory outcome. Thirty-five patients with refractory TLE undergoing pre-surgical evaluation for temporal lobectomy and 30 normal subjects performed a complex visual scene-encoding task during fMRI scanning at 1.5 T using a 10-min protocol. Encoding performance was evaluated with subsequent recognition testing. Twenty-three patients also completed the same task again outside the scanner, an average of 6.9 months following surgery. A region of interest (ROI) analysis was used to quantify activation within hippocampal and a larger mesial temporal lobe ROI consisting of hippocampus, parahippocampus and fusiform gyrus (HPF) as defined by a published template. Normal subjects showed almost symmetrical activation within these ROI. TLE patients showed greater asymmetry. Asymmetry ratios (ARs) from the HPF ROI correlated significantly with memory lateralization by intracarotid amobarbital testing. HPF ARs also correlated significantly with memory outcome, as determined by a change in scene recognition between pre-surgical and post-surgical trials. When absolute activation within the HPF ROI was considered, a significant inverse correlation between activation ipsilateral to temporal lobectomy and memory outcome was observed, with no significant correlation in the contralateral HPF ROI. Although further technical improvements and prospective clinical validation are required, these results suggest that mesial temporal memory activation detected by fMRI during complex visual scene encoding correlates with post-surgical memory outcome and supports the notion that this approach will ultimately contribute to patient management.

Objective: To quantify the loss of pigmented neurons in the substantia nigra (SN) of autopsy-confirmed Parkinson disease (PD) and incidental Lewy body disease (ILBD) vs age-matched controls (C).Methods: Unbiased stereology methods were used to rigorously count number and measure volumes of nigral pigmented neurons in PD, ILBD, and C brains. The obtained stereologic results were correlated with Lewy body (LB), amyloid plaque (AP), neurofibrillary tangle (NFT), and vascular pathology loads assessed in nigral and extranigral regions of each PD, ILBD, and C brain. The stereologic measurements were also correlated to predeath motor and cognitive scores as available for each participant.Results: A marked nigral neuronal loss (NNL) in PD (282%) and ILBD (240%) compared to C (p , 0.0001) was found. While there was significant correlation between NNL and LB in some cortical areas of PD (i.e., olfactory bulb), there were no correlations between NNL and LB, AP, or NFT loads or cerebral infarct volumes in any other examined regions for PD and ILBD brains.Conclusions: Using unbiased stereology methods, we show that there is a significant loss and absence of hypertrophic changes in nigral pigmented neurons of ILBD in comparison to C brains. Intriguingly, no significant correlations were found between NNL and LB loads in the SN of both PD and ILBD brains. These autopsy-verified stereologically based findings are novel and support ILBD as a pathologic condition. These results suggest possible new and alternative pathophysiologic hypotheses on the actual relationship between NNL and LB pathology.