Sara J. Swanson

Functional Magnetic Resonance Imaging Mapping of the Motor Cortex in Patients with Cerebral Tumors

OBJECTIVE The purpose of this study was to determine the usefulness of functional magnetic resonance imaging (FMRI) to map cerebral functions in patients with frontal or parietal tumors. METHODS Charts and images of patients with cerebral tumors or vascular malformations who underwent FMRI with an echoplanar technique were reviewed. The FMRI maps of motor (11 patients), tactile sensory (12 patients), and language tasks (4 patients) were obtained. The location of the FMRI activation and the positive responses to intraoperative cortical stimulation were compared. The reliability of the paradigms for mapping the rolandic cortex was evaluated. RESULTS Rolandic cortex was activated by tactile tasks in all 12 patients and by motor tasks in 10 of 11 patients. Language tasks elicited activation in each of the four patients. Activation was obtained within edematous brain and adjacent to tumors. FMRI in three cases with intraoperative electrocortical mapping results showed activation for a language, tactile, or motor task within the same gyrus in which stimulation elicited a related motor, sensory, or language function. In patients with > 2 cm between the margin of the tumor, as revealed by magnetic resonance imaging, and the activation, no decline in motor function occurred from surgical resection. CONCLUSIONS FMRI of tactile, motor, and language tasks is feasible in patients with cerebral tumors. FMRI shows promise as a means of determining the risk of a postoperative motor deficit from surgical resection of frontal or parietal tumors.

Use of preoperative functional neuroimaging to predict language deficits from epilepsy surgery

Background: Left anterior temporal lobectomy (L-ATL) may be complicated by confrontation naming deficits. Objective: To determine whether preoperative fMRI predicts such deficits in patients with epilepsy undergoing L-ATL. Methods: Twenty-four patients with L-ATL underwent preoperative language mapping with fMRI, preoperative intracarotid amobarbital (Wada) testing for language dominance, and pre- and postoperative neuropsychological testing. fMRI laterality indexes (LIs), reflecting the interhemispheric difference between activated volumes in left and right homologous regions of interest, were calculated for each patient. Relationships between the fMRI LI, Wada language dominance, and naming outcome were examined. Results: Both the fMRI LI (p < 0.001) and the Wada test (p < 0.05) were predictive of naming outcome. fMRI showed 100% sensitivity and 73% specificity in predicting significant naming decline. Both fMRI and the Wada test were more predictive than age at seizure onset or preoperative naming performance. Conclusions: Preoperative fMRI predicted naming decline in patients undergoing left anterior temporal lobectomy surgery.

Use of preoperative functional MRI to predict verbal memory decline after temporal lobe epilepsy surgery.

Purpose: Verbal memory decline is a frequent complication of left anterior temporal lobectomy (L‐ATL). The goal of this study was to determine whether preoperative language mapping using functional magnetic resonance imaging (fMRI) is useful for predicting which patients are likely to experience verbal memory decline after L‐ATL.

A comparison of five fMRI protocols for mapping speech comprehension systems.

Aims:  Many fMRI protocols for localizing speech comprehension have been described, but there has been little quantitative comparison of these methods. We compared five such protocols in terms of areas activated, extent of activation, and lateralization.

Side of seizure focus predicts left medial temporal lobe activation during verbal encoding

Objective: Functional MRI (FMRI) was used to investigate the effect of medial temporal lobe (MTL) pathology on activation of language encoding areas in patients with temporal lobe epilepsy (TLE). Methods: Whole-brain FMRI was obtained. Twenty-eight patients with either left TLE(LTLE) or right TLE (RTLE) performed a semantic decision task alternating with an auditory perceptual task. Results: Activation of language areas in the frontal and parietal lobes was similar in both groups, with no group differences in the total number of active voxels. However, the RTLE group showed much stronger activation of the left MTL, including the hippocampus, parahippocampal gyrus, and collateral sulcus, than did the LTLE group. Conclusions: Activation of the left MTL during semantic encoding discriminates patients with RTLE and LTLE. This FMRI technique may potentially be of use in determining memory lateralization and for predicting the side of seizure focus in TLE.

Recognition and identification of famous faces in patients with unilateral temporal lobe epilepsy

We examined the performance of 21 patients with unilateral temporal lobe epilepsy (TLE) and hippocampal damage (10 lefts, and 11 rights) and 10 age-matched controls on the recognition and identification (name and occupation) of well-known faces. Famous face stimuli were selected from four time periods; 1970s, 1980s, 1990-1994, and 1995-1996. Differential patterns of performance were observed for the left and right TLE group across distinct face processing components. The left TLE group showed a selective impairment in naming famous faces while they performed similar to the controls in face recognition and semantic identification (i.e. occupation). In contrast, the right TLE group was impaired across all components of face memory; face recognition, semantic identification, and face naming. Face naming impairment in the left TLE group was characterized by a temporal gradient with better naming performance for famous faces from more distant time periods. Findings are discussed in terms of the role of the temporal lobe system for the acquisition, retention, and retrieval of face semantic networks, and the differential effects of lateralized temporal lobe lesions in this process.

Memory outcome after left anterior temporal lobectomy in patients with expected and reversed Wada memory asymmetry scores.

Summary:  Purpose: The ideal candidate for anterior temporal lobectomy surgery shows a Wada memory asymmetry (WMA) score characterized by better memory performance in the hemisphere contralateral to the seizure focus relative to the ipsilateral (surgical) hemisphere. However, some surgical candidates show a reversed WMA or better Wada memory performance in the hemisphere of surgical interest relative to the hemisphere contralateral to the seizure focus. To date, no data are available contrasting memory and seizure outcome for these two Wada groups. The present study compared memory and seizure outcome after left anterior temporal lobectomy (L‐ATL) in patients showing expected and reversed WMA scores, and also examined the relationship of the individual hemisphere Wada memory scores for predicting verbal memory outcome after L‐ATL.

A comparison of two fMRI methods for predicting verbal memory decline after left temporal lobectomy: language lateralization versus hippocampal activation asymmetry.

Purpose:  Language lateralization measured by preoperative functional magnetic resonance imaging (fMRI) was shown recently to be predictive of verbal memory outcome in patients undergoing left anterior temporal lobe (L‐ATL) resection. The aim of this study was to determine whether language lateralization or functional lateralization in the hippocampus is a better predictor of outcome in this setting.

The contribution of neuropsychology to diagnostic assessment in epilepsy

Neuropsychology plays a vital role in the treatment of epilepsy, providing information on the effects of seizures on higher cortical functions through the measurement of behavioral abilities and disabilities. This is accomplished through the design, administration and interpretation of neuropsychological tests, including those used in functional neuroimaging or cortical mapping and in intracarotid anesthetic procedures. The objective of this paper is to define and summarize in some detail the role and methods of neuropsychologists in specialized epilepsy centers. Included are information and recommendations regarding basic ingredients of a thorough neuropsychological assessment in the epilepsy setting, as well as suggestions for an abbreviated alternative exam when needed, with emphasis on functions associated with specific brain regions. The paper is intended for novice and experienced neuropsychologists to enable them to develop or evaluate their current practices, and also for other clinicians, who seek a better understanding of the methodology underlying the neuropsychological input to their work.

Preictal pseudosleep: a new finding in psychogenic seizures

Background and objective: The diagnosis of psychogenic seizures (pseudoseizures) may be difficult and usually rests on video-EEG monitoring. We observed that pseudoseizures often arise out of a state that we termed preictal pseudosleep. The objective of this study was to investigate this potential new sign in pseudoseizures. Methods: We prospectively studied all patients who underwent noninvasive monitoring over a 10-month period. Patients were monitored for a duration of 1 to 19 days (mean 4.9), and were divided into two groups: pseudoseizures and epileptic seizures. Patients with both conditions were excluded. Preictal pseudosleep was defined as a state that resembled normal sleep by behavioral criteria alone (i.e. patient motionless and eyes closed), while EEG showed evidence of wakefulness (alpha rhythm, active EMG, and rapid eye movement). This state had to be sustained for at least 1 minute before clinical onset. Results: Patients had 1 to 25 (mean 7) clinical events recorded. Preictal pseudosleep was seen in 10 of 18 patients with pseudoseizures and in none of 39 patients with epileptic seizures, yielding a sensitivity of 56% and a specificity of 100% for pseudoseizures. Conclusion: Because of a high specificity, preictal pseudosleep may be a useful adjunctive finding to support the diagnosis of pseudoseizures. NEUROLOGY 1996;47: 63-67