Faculty Bibliography

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.

Two competing hypotheses (i.e., disruption of semantic networks vs. search inefficiency) concerning the mechanisms underlying impaired semantic verbal fluency in temporal lobe epilepsy (TLE) were tested within a single paradigm. Reports that semantic verbal fluency is more impaired in left than right TLE groups were confirmed by the findings that the left TLE group produced fewer words on a supermarket fluency task than did the normal control (NC) group, and that the performance of the right TLE group was intermediate to that of the left TLE and NC groups. Because both TLE groups generated fewer words per category of supermarket items sampled, and produced a higher ratio of category labels relative to category exemplars than did the NC group, it can be surmised that TLE disrupts semantic memory networks. The findings did not support the competing hypothesis that reduced semantic verbal fluency in TLE is a manifestation of inefficient search/retrieval strategies, possibly associated with distal frontal lobe pathophysiology. Specifically, the TLE and NC groups did not differ significantly in their mean number of perseverations, intrusions, or search efficiency (operationalized as the ratio of the number of shifts between categories to the number of categories sampled).

Bismuth subsalicylate preparations are over-the-counter products for gastrointestinal complaints. Bismuth toxicity causes delirium, psychosis, ataxia, myoclonus, and seizures and is reversible over several weeks or months, when bismuth intake is stopped. We report a 54-year-old man with a 6-week history of progressive confusion and memory difficulty and a 2-3-week history of involuntary movements and gait impairment. His encephalopathy was further characterized by marked multifocal myoclonic jerks, coarse postural tremors, postural instability, and gait ataxia. He gradually improved. Extensive toxic, metabolic, and infectious workup demonstrated bismuth toxicity. Spinal tap and brain magnetic resonance scan were normal. Electroencephalography showed bihemispheric slowing. As his encephalopathy cleared, he reported using bismuth subsalicylate long term (daily intake of 8 oz). Bismuth levels 5 weeks after cessation of bismuth were elevated and normalized after 12 weeks. He followed a typical course for bismuth toxicity with subacute progressive encephalopathy and gradual recovery. Creutzfeldt-Jakob was strongly considered due to his rapidly progressive encephalopathy, multifocal myoclonus, and ataxia. Due to its rarity, bismuth toxicity is often overlooked. We hope this presentation will increase recognition of bismuth toxicity. We believe more detailed labeling of bismuth products is needed to avoid similar toxicity from this readily available product.

OBJECTIVE: This study sought to elucidate the relation of clinical, neuropsychological, and seizure variables to chronic and postictal psychoses in patients with temporal lobe epilepsy. METHOD: Forty-four patients with treatment-refractory temporal lobe epilepsy were given formal psychiatric evaluations; 29 patients had no psychiatric disorder or a nonpsychotic disorder, eight patients had postictal psychoses, and seven patients had chronic psychoses. Comparisons of clinical, neuropsychological, magnetic resonance imaging, and seizure variables were made between the nonpsychotic and the psychotic patients and, secondarily, between the patients with transient postictal psychoses and those with chronic psychoses. RESULTS: Bitemporal seizure foci, clustering of seizures, and absence of febrile convulsions were associated with both postictal psychoses and chronic psychoses. Younger age at onset of epilepsy and lower verbal and full-scale IQs differentiated the patients with chronic psychoses from those with postictal psychoses. CONCLUSIONS: Patients with temporal lobe epilepsy with chronic and postictal psychoses show similar profiles of clinical and seizure variables, suggesting shared etiologic factors. These factors may increase the propensity to develop psychotic symptoms, while other factors, such as time of onset of epilepsy and underlying neuropathology, may determine whether transient or chronic psychotic symptoms develop. Even among patients with treatment-refractory temporal lobe epilepsy, a specific subgroup of patients, characterized by bitemporal seizure foci, an absence of febrile convulsions, and a history of clustering of seizures, appears to be particularly prone to develop psychotic disorders. A process similar to secondary epileptogenesis may be involved in the development of the psychoses.

OBJECTIVE: Cerebellar atrophy has been noted in patients with phenytoin exposure. This finding has been attributed by some investigators to seizures, but by others to phenytoin. Previous studies included patients with mental retardation and convulsive seizures. We undertook a study in a group of nonretarded patients with partial epilepsy to better elucidate the cause of the cerebellar atrophy. DESIGN: Case control study. SETTING: Referral population from an epilepsy center. PATIENTS: Thirty-six patients with partial epilepsy and long-term phenytoin exposure were selected from a consecutive sample of admissions to an epilepsy center. Patients with histories of ethanol abuse, perinatal distress, anoxia, status epilepticus, or neurodegenerative disorders were excluded. Age- and sex-matched controls were selected from a pool of healthy volunteers and patients who had undergone magnetic resonance imaging for complaints of headache and dizziness. INTERVENTIONS: All patients and controls underwent magnetic resonance imaging. MAIN OUTCOME MEASURE: Degree of cerebellar atrophy. RESULTS: The magnetic resonance imaging scans were reviewed in a blind fashion. A rating was assigned to each scan based on the degree of cerebellar atrophy. Cerebellar atrophy was significantly more pronounced in patients than in controls. No correlation was found between cerebellar atrophy and variables reflective of seizure severity or degree of phenytoin exposure. CONCLUSIONS: Cerebellar atrophy may be seen in phenytoin-exposed patients with epilepsy in the absence of generalized tonic-clonic seizures or preexistent brain damage. Whether it is the phenytoin or the seizures that play the primary etiologic role remains unanswered. These factors may be synergistic.

A 25-year-old woman with documented generalized seizures evoked by playing checkers was given a battery of psychological tests as well as a series of cognitive and non-game-related tasks during a session of intensive EEG-video monitoring. Generalized epileptiform discharges during each task, as well as during intervals of checkers playing, were quantified to determine possible triggering factors. Previous reports have discussed the roles of attention, concentration, stress, thinking, and spatial processing in similar cases. Our analysis showed significant activation of the EEG only with tasks involving strategic thinking, i.e., considering a sequence of moves based on evaluating the consequences of previous moves.

This study investigated the use of three-dimensional fast low-angle shot (FLASH) imaging and computer-assisted morphometry for identifying hippocampal changes associated with unilateral temporal lobe seizures. Contiguous 3.1-mm coronal FLASH images were obtained in 28 patients with electroencephalographically verified left (n = 17) or right (n = 11) temporal lobe seizures and 28 age- and sex-matched control subjects. Hippocampal volumes were calculated with the use of a computerized mensuration system developed for detailed morphometric assessment. The results of a multivariate analysis of variance revealed a significant group difference by hemisphere interaction (F = 26.3, p less than .001). Significant reductions in left hippocampal volume (32%, p less than .001) were exhibited in patients with left temporal lobe seizures, and significant reductions in right hippocampal volume (35%, p less than .001) were seen in patients with right temporal lobe seizures. A discriminant analysis with the use of left and right hippocampal volumes classified patients with left temporal lobe seizures with 94% sensitivity and 73% specificity and patients with right temporal lobe seizures with 89% sensitivity and 94% specificity. The results of this study demonstrate that unilateral temporal lobe seizures are accompanied by significant reductions in hippocampal volume ipsilateral to the seizure focus. The use of FLASH imaging and computer-assisted morphometry of the hippocampus appears to provide valuable structural information for confirming the laterality of the electroencephalographic seizure focus.