Long-term ictal monitoring with subdural strip electrodes: prognostic factors for selecting temporal lobectomy candidates.

Long-term electrocorticographic (ECoG) monitoring data from subdural strip electrodes are analyzed to determine factors associated with seizure-free outcome from anterior temporal lobectomy. A total of 89 consecutive patients with complex partial seizures, in whom long-term ictal video/scalp electroencephalographic monitoring was insufficient to localize their epileptogenic focus, were subsequently evaluated with long-term ictal ECoG monitoring using subdural strip electrodes. Each patient underwent anterior temporal lobectomy based on the ictal ECoG data and has been followed for at least 1 year. The following parameters were found to be statistically significant in predicting a seizure-free outcome: unilateral onset, electrical onset pattern beginning as fast spike trains, absence of frontal lobe background desynchronization at onset, and an interhemispheric propagation time of greater than 8 seconds. Electrocorticographic criteria that were not associated with seizure outcome included: right- versus left-sided onset, time from electrical to clinical ictal onset, focality of onset (number of strip electrode contacts involved), and stereotypical ECoG onset. When present, the interictal focus was concordant with the ictal focus in most patients (96%), but was falsely lateralizing in 4% of cases. It is suggested that these data should improve patient selection for temporal lobectomy when subdural strip monitoring is used during preoperative evaluation.

Results of reoperation for failed epilepsy surgery.

A total of 37 patients who failed epilepsy surgery were evaluated with magnetic resonance imaging and long-term scalp electroencephalographic monitoring before reoperation. Repeat surgery involved focal resections after initial focal resections (30 cases) or stereotactic lesions (one case), or focal resections following anterior corpus callosotomy (six cases). Patients with initial focal resections followed by enlargement of the original operative site had the most successful outcome, especially those with complex partial seizures of temporal lobe origin. The most common cause for poor outcome of the original operation in patients with temporal lobe epilepsy was insufficient hippocampal resection. Patients who were most likely to benefit from reoperation were: 1) those with initially incompletely resected structural lesions; 2) those who were initially evaluated with invasive ictal monitoring; and 3) those who underwent further resection of the initial operative site rather than resection of a different cortical region.

Wisconsin Card Sorting Test performance in patients with complex partial seizures of temporal-lobe origin.

Wisconsin Card Sorting Test (WCST) performance was investigated in patients with complex partial seizures (CPS) of dominant (n = 16) or nondominant (n = 19) temporal-lobe origin as well as in an epilepsy control group (n = 6) which consisted largely of patients with primary generalized epilepsies. Fifty seven percent of the CPS group (39% of dominant and 74% of nondominant temporal-lobe patients) performed in a manner suggestive of frontal-lobe pathology compared to 17% of the epilepsy controls. There were no differences among the groups in the number of categories achieved, but there were substantial qualitative differences in problem-solving efficiency. Nondominant temporal patients manifested more total errors and perseverative errors relative to both dominant temporal and epilepsy controls, and more perseverative responses relative to epilepsy controls. Dominant temporal-lobe patients showed more perseverative errors than epilepsy controls. Finally, a consecutive series of patients who underwent partial temporal-lobe resection were examined 6 months post-surgically and they were found to manifest significantly fewer perseverative responses. The possible reasons for "frontal-like" performance in CPS patients with documented temporal-lobe pathology are discussed and a specific hypothesis is suggested.

The interrelationship between language function and verbal learning/memory performance in patients with complex partial seizures.

The purpose of this investigation was to inquire into the relationship between demographic, seizure related, and language factors with the adequacy of verbal learning and memory function in 25 patients with complex partial seizures of dominant temporal lobe origin. Language function in general, and measures of verbal comprehension (aural and reading) and retrieval ability (naming and associative fluency) in particular, emerged as the most robust predictors of verbal learning and memory performance in this sample. Our findings both supported and extended the hypothesis of Mayeux et al. (1980) of a relationship between adequacy of language function and verbal learning and memory performance in patients with complex partial seizures. The implications of these findings for studies investigating the relationship between complex partial seizures/temporal lobe pathology and memory function are discussed.

The MacAndrew Alcoholism Scale in epilepsy: a high false positive error rate.

A substantial proportion of patients with epilepsy seen in a large medical center were found to be incorrectly classified as possible substance abusers by the MacAndrew Alcoholism Scale (MAC) of the MMPI. Demographic variables, IQs, and MAC scale raw scores were compiled for a sample of 29 male and 33 female seizure patients. No significant or meaningful differences were found between the sexes; therefore, the sample was treated as a single group. False positive error rates on the MAC scale were 48.39% when MacAndrew's originally proposed raw score cut-off of 24 was used; 30.65% with a cut-off of 26; 20.97% with a cut-off of 28; and 9.68% with a cut-off of 30. A similarity of experiential and behavioral characteristics between seizure patients and substance abusers is suggested as a possible reason for the findings. A greater awareness of this high false positive rate for epilepsy patients is needed to differentiate drug-/alcohol-induced from non-induced seizures and to prevent inappropriate labeling of seizure patients by the various professional groups who utilize the MMPI. Suggestions are made for future research.

The neurological, psychosocial and demographic correlates of hypergraphia in patients with epilepsy.

The multiaetiological determinants and correlates of interictal hypergraphia in patients with epilepsy were studied. A variety of neurological, psychosocial and demographic variables were examined in order to determine their relationship to experimental and clinically derived measures of hypergraphia in a sample of 50 patients with epilepsy. The results indicate that hypergraphia is of multifactorial origin in general, with especially strong relationships with measures of psychopathology. These results are related to the larger literature concerned with interictal behavioural change in patients with epilepsy.

Methohexital activation of epileptogenic foci during acute electrocorticography.

Methohexital was used as an activating agent in 62 patients undergoing focal cortical resections of epileptogenic foci and in six patients undergoing chronic electroencephalogram (EEG)/video monitoring with intracranial strip electrodes. In 87% of cases, methohexital caused selective activation of the epileptogenic focus during acute electrocorticography (ECoG). This activation appeared to be specific for the epileptogenic focus and did not cause epileptiform spiking from adjacent nonepileptogenic cortex. This ECoG activation occurred whether patients received local or general anesthesia. Sixty-five percent of patients demonstrated adequate activation with as little as 25 mg of drug. Methohexital is a safe and reliable method of activating epileptogenic foci during acute ECoG recordings and can decrease the time for ECoG recordings during surgery.

Memory function and verbal learning ability in patients with complex partial seizures of temporal lobe origin.

A variety of experimental paradigms have been utilized to study verbal learning and memory ability in patients with epilepsy. One commonly used paradigm, the free recall of a list(s) of related or unrelated words, has revealed a variety of performance anomalies in patients with complex partial seizures (CPS) of temporal lobe origin, but published studies have varied markedly in important methodological details, making it difficult to interpret discrepant findings as well as to assess the generalizability of results. The purpose of this investigation was to simultaneously inquire into several aspects of verbal learning and memory function that have been reported or hypothesized to be compromised in individuals with CPS of left temporal lobe origin. Thirty patients with CPS of lateralized temporal lobe onset [15 left temporal (LT) and 15 right temporal (RT)] were compared with 15 matched controls (NC) on several measures derived from the California Verbal Learning Test (CVLT), i.e., verbal learning ability, immediate free recall, presence of retroactive interference effects, semantic organization, retrieval efficiency, and recognition memory. Compared to RT and NC groups, the LT patients manifested poorer verbal learning ability, impaired immediate memory, and increased difficulty in the retrieval of verbal material from memory store. Compared to NC subjects, the LT group showed poorer semantic organization in their verbal learning and recall. The RT and NC groups were essentially similar in all respects. Finally, the clinical utility of these findings were investigated, and a series of decision rules designed to separate LT from RT patients was derived.

Somatosensory evoked potentials in pure sensory stroke and related conditions.

Somatosensory evoked potentials were reviewed for their correlation with CT scan and clinical features of ischemic "pure sensory stroke" and "pure sensorimotor stroke". Somatosensory evoked potentials were normal in all 11 cases of pure sensory stroke, and CT was normal in ten. The N2-P2 components of the somatosensory evoked potentials were abnormal in all 4 cases of pure sensorimotor stroke, and all had low density CT lesions in the lateral thalamus and/or posterior limb of the internal capsule. It is concluded that somatosensory evoked potentials and CT scans are routinely abnormal in pure sensorimotor stroke, but they are consistently normal in pure sensory stroke, and should not be interpreted as evidence against a clinical diagnosis of pure sensory stroke.

EEG changes during carotid endarterectomy: drug effect and embolism.

Clinical neurological status and the electroencephalogram (EEG) were monitored during right carotid endarterectomy under regional anaesthesia in a patient who had suffered two prior cerebral infarctions. No change in EEG or clinical status was seen with occlusion of the carotid artery, but generalized encephalopathic changes were seen after a small dose of narcotic given before carotid occlusion. Bihemispheric changes in EEG and neurological status occurred upon release of carotid occlusion. This case demonstrates three important points. First, EEG changes can be seen with sedative or anaesthetic agents in patients who have previously suffered brain injury. Second, temporary neural dysfunction may be seen remote from the site of a localized injury to the brain--a phenomenon known as diaschisis. Finally, this report reiterates the observation that the risk of injury to the brain during carotid endarterectomy is not limited to the period of possible ischaemia during occlusion of the carotid artery.

Dacrystic epilepsy.

We observed a 69 year old patient who had spontaneous paroxysmal attacks of weeping with lacrimation, contorted facies, and (usually) head-turning to the right. These episodes were followed by confusion and amnesia. During a pentylenetetrazol-evoked attack the EEG showed a right temporal delta rhythm. Atrophy, particularly of the right temporal regions, was noted on pneumoencephalography. We propose the term "dacrystic epilepsy" for this rare type of seizure disorder.

Prognostic significance of episodic low amplitude or relatively isoelectric EEG patterns.

Electroencephalograms demonstrating episodes of relative iso-electric activity in 14 comatose patients are divided into three patterns. The first, Type I, showed brief low amplitude or relatively iso-electric episodes intermixed with slow activity. The second, Type II, showed epileptogenic activity with episodes of relative iso-electricity. The third, Type III, showed burst suppression in which iso-electric intervals were of greater duration than periodic slow activity. All patients expired, indicating grave prognostic implications for all three patterns.