Faculty Bibliography

This study examined the relation between complaints of memory disturbance and measures of mood and memory functioning in 55 patients with serological evidence of late-stage Lyme Borreliosis (LB). Patients completed the Self-Ratings of Memory Questionnaire (SRMQ) and the Beck Depression Inventory. Memory functioning was assessed with the California Verbal Learning Test. Depressed patients exhibited more frequent complaints of memory disturbance on the SRMQ, although their pattern of responses did not differ from nondepressed patients. There was a significant correlation between subjective memory ratings and self-reported depression (Spearman rho = -.57, p < .001). No relation was observed between subjective memory ratings and objective memory performance. The results indicate subjective complaints of more severe memory disturbance in patients with LB and depression. Particular attention should be paid to the assessment of depression and subjective symptoms of memory disturbance when administering neuropsychological tests of memory functioning in patients with LB.

BACKGROUND: The emergence of psychogenic seizures after surgery for epilepsy is not well recognized. OBJECTIVES: To identify the frequency of psychogenic seizures in an 11-year surgical experience and to characterize the patients with this complication. METHODS: Ninety-six patients underwent surgery for epilepsy between 1985 and 1996. The surgical database was reviewed and all patients who experienced postoperative psychogenic seizures were identified. Patients were characterized by sex, age, psychopathologic conditions, full-scale IQ, duration of epilepsy, surgical procedure, and operative complications. Patients were compared with the surgical group as a whole for these variables. SETTING: A comprehensive epilepsy center. RESULTS: Five patients were identified: 3 men and 2 women. Mean full-scale IQ was 73 (range, 66-82). Mean age was 29.8 years (range, 22-36 years). Three patients were diagnosed as having psychosis, 1 with borderline personality disorder and 1 with generalized anxiety. Operations included 4 anterior temporal lobectomies and 1 occipital lobectomy. Two patients experienced operative complications. Compared with the surgical cohort, patients had a higher frequency of preoperative psychopathologic conditions, lower mean full-scale IQ, and a greater occurrence of operative complications. CONCLUSIONS: (1) Patients can develop new-onset psychogenic seizures after surgery for epilepsy. (2) Low full-scale IQ, serious preoperative psychopathologic conditions, and major surgical complications may be risk factors. (3) Atypical postoperative seizures should be evaluated with video electroencephalographic monitoring before concluding that they are epileptic.

PURPOSE: Considerable debate exists concerning whether the presence of low preoperative IQ should be a contraindication for focal resective epilepsy surgery. METHODS: We examined the relationship between baseline IQ scores and seizure outcome in 1,034 temporal lobectomy cases from eight epilepsy surgery centers participating in the Bozeman Epilepsy Consortium. RESULTS: Those patients who continued to have seizures following surgery had statistically lower preoperative IQ scores than those who were seizure-free (p < 0.009), but only by 2.3 points. This small but statistically significant relationship was fairly robust; it was observed across seven of the eight centers, and indicates that the findings can be generalized. Among patients with IQ scores of < or = 75, 32.8% continued to have seizures following surgery, whereas 23.8% and 16.9% were not seizure-free when IQ scores were between 76 and 109 and > or = 110, respectively. Relative risk analyses revealed no significant increase in risk among patients with low IQ scores who had no structural lesions other than mesial temporal sclerosis. However, patients with IQ scores of < or = 75 had nearly a fourfold (390%) increase in risk for continued seizures as compared with those with higher IQ scores if structural lesions were present. CONCLUSIONS: While our results suggest that preoperative IQ scores alone are not good predictors of seizure outcome and should not be used to exclude patients as potential surgical candidates. IQ scores can be useful for counseling patients and their families concerning the relative risks of surgery.

OBJECTIVES: To examine the degree and frequency of reductions in hippocampal volume in patients with temporal lobe epilepsy with and without a history of febrile seizures. METHODS: In vivo measures of hippocampal volume were computed from three dimensional gradient echo (FLASH) images in 44 patients undergoing comprehensive evaluations for epilepsy surgery. Twenty one patients (48%) reported a history of febrile seizures. The volumes from these patients were compared with those from 23 patients without a history of febrile seizures and 34 healthy controls. RESULTS: The febrile seizure group had significant reductions in volume, both ipsilateral (30% decrease) and contralateral (15% decrease), to the EEG seizure focus. Twelve of 18 patients with febrile seizures exhibited clinically significant ipsilateral volume reductions, defined as volumes falling 2 SD below the mean obtained from the control sample. Only four of 19 patients without febrile seizures exhibited this degree of reduction. No significant correlations were found between seizure variables (for example, duration of epilepsy, seizure frequency) and ipsilateral reductions in volume. However, a significant inverse correlation (r=-0.45, P<0.05) between seizure frequency and the volume of the hippocampus contralateral to the seizure focus was found in the febrile seizure group. CONCLUSION: These results suggest that a history of febrile seizures is associated with the finding of a smaller hippocampus on the side ipsilateral to the subsequent temporal lobe focus whereas chronic factors seem to be be related to pathology contralateral to the seizure focus.

Tests of facial recognition and spatial learning were administered to presurgical patients with unilateral temporal lobe EEG foci. Right temporal lobe patients obtained lower facial recognition scores than left temporal lobe patients. The groups performed equally on the spatial learning test. A factor analysis revealed two independent factors: a general visuospatial factor and a more specific facial identification factor. The findings provide support for the existence of two dissociable visual processing systems. Memory impairments associated with right temporal lobe dysfunction may be characterized as an impairment in a ventral visual processing system responsible for facial memory and pattern recognition.

The construct of nonverbal memory, as assessed by figural reproduction tests, has recently been questioned by a number of investigators. The purpose of this study was to reexamine this construct and its relationship to right temporal lobe dysfunction. Figural reproduction test scores were examined in 757 epilepsy surgery candidates obtained from 8 epilepsy centers participating in the Bozeman Epilepsy Consortium. All participants exhibited unequivocal evidence of left (LTL) or right (RTL) temporal lobe epilepsy observed in ictal and interictal EEG recordings. All subjects also had IQ scores exceeding 70, right-hand preference, and left hemisphere language dominance confirmed by intracarotid sodium amytal testing. Comparisons of LTL and RTL groups showed no significant differences in scores on the Visual Reproduction subtests from the Wechsler Memory Scale (WMS) or Wechsler Memory Scale-Revised (WMS-R) or on the copy and delayed recall conditions of the Rey-Osterrieth Complex Figure Test (ROCFT). Significant differences were observed among centers on WMS and ROCFT scores, which are likely to be a result of variations in administration and/or scoring procedures. The lack of significant differences between LTL and RTL groups in this large sample raise questions about the nature of nonverbal memory and its relationship to right temporal lobe dysfunction.

In a descriptive analysis of 158 patients with temporal lobe epilepsy, Taylor (1969) reported that the age of first seizure varied systematically as a function of laterality and sex. We conducted inferential analyses of Taylor's original data which (1) provided support for his proposal of disproportionate left hemisphere vulnerability to seizure onset in early life, but (2) failed to provide evidence of sex differences in age of onset of unilateral seizures. Examination of these effects in a larger sample of 844 patients drawn from the Bozeman Epilepsy Consortium provided some additional support for findings from the inferential analysis. Specifically, the left hemisphere appeared more vulnerable to seizure onset in childhood, this increased vulnerability extending to about age 5 years. Age of onset of seizures was not different when males and females were compared. Thus, reanalysis of Taylor's original data as well as examination of data from a larger, more contemporary sample suggest that seizure onset varies as a function of laterality, but not sex.

BACKGROUND: Converging evidence has suggested that the abnormalities in brain morphology observed in schizophrenia are similar to those seen in temporal lobe epilepsy (TLE). The purpose of this study was to compare the features of these groups directly with measures of the brain using magnetic resonance (MR) morphometry. METHOD: Morphometric measures of ventricular and hippocampal volumes obtained from FLASH MR images were studied in 32 patients with first-episode schizophrenia (FES), 39 patients with TLE (21 left, 18 right), and 42 healthy controls. RESULTS: Ventricular volumes in the FES and TLE groups were both significantly larger that those seen in controls and did not differ from each other. The FES group showed significantly larger temporal horns, while the TLE group had relatively larger frontal horns. Analyses of hippocampal volumes revealed a significant group by hemisphere effect. The FES group showed relative reductions in left hippocampal volume that were comparable only to TLE patients with seizures originating from the left hemisphere. CONCLUSION: The results indicate that FES and TLE groups both show evidence of ventricular enlargement. Lateralised morphological abnormalities of the hippocampal formation in FES and left TLE are comparable, and may be specific to temporolimbic regions.

BACKGROUND: To objectively measure memory functioning in patients with Lyme borreliosis and examine the relationship between subjective reports of memory dysfunction and actual impairment. METHOD: A prospective pretreatment study of patients with Lyme borreliosis (N = 21), a patient control group (osteomyelitis, N = 21), and healthy controls (N = 21) was conducted by using tests of verbal memory functioning (California Verbal Learning Test) and self-reported depression (Beck Depression Inventory-Cognitive Index), fatigue (Fatigue Severity Scale), and subjective ratings of memory abilities (Self-Rating Scale of Memory Functions). RESULTS: Patients with Lyme borreliosis performed worse than healthy controls on verbal memory testing, but did not perform significantly differently from patient controls. Lyme borreliosis patients reported increased fatigue, which was correlated with poorer memory performance. Although the Lyme borreliosis patients rated their memory as more impaired, subjective complaints were not correlated with objective memory scores. CONCLUSION: These findings suggest impaired memory performance is not specific to Lyme borreliosis and may be a result of evaluating cognitive functioning in patients with physical illness and somatic complaints. Fatigue is a prominent presenting complaint in patients with Lyme borreliosis and needs to be controlled for since it is known to influence neuropsychological performance. Subjective complaints are not correlated with objective memory assessment, so self-report of memory impairment should not be the criterion for inclusion in studies investigating cognitive manifestations of Lyme borreliosis.

OBJECTIVE: Fluorodeoxyglucose positron emission tomography (FDG-PET) studies of temporal lobe epilepsy (TLE) generally report interictal hypometabolism in the vicinity of the seizure focus. Yet, other evidence suggests that interictal metabolic abnormalities might extend to remote brain areas. We used FDG-PET to evaluate metabolism in selected regions distant from the focus in TLE. SUBJECTS: Twenty adult patients with medically intractable TLE were selected by criteria favoring a unilateral mesiobasal temporal focus. Structural imaging in this sample were normal except for medial temporal sclerosis in 13 patients. Twenty normal volunteers were controls. DESIGN: PET imaging was performed interictally. Regional glucose metabolism normalized by global metabolism was analyzed using t tests and correlation analysis. RESULTS: Ipsilateral to the seizure focus, metabolism was depressed compared with normal in the temporal pole (p = 0.001), but relatively elevated in the mesiobasal region (p = 0.005). Contralateral to the focus, metabolism was elevated in lateral temporal cortex (p = 0.0003) and mesiobasal regions (p = 0.0001). Metabolic correlation between ipsilateral and contralateral mesiobasal regions was similar in normal subjects (r = 0.74) and patients (r = 0.68). In contrast, correlations were abnormal between temporal poles and other temporal lobe subregions, both ipsilateral and contralateral to the seizure focus. CONCLUSIONS: Relative to normal values, both elevations and depressions of metabolism exist interictally in TLE. Such abnormalities, and accompanying changes in interregional correlations, may have wide spatial distribution. These findings are atypical among PET studies but are consistent with other physiologic, anatomic, and neuropsychological investigations of TLE.