Detection of EEG background abnormalities in epilepsy by a new spectral index.

OBJECTIVE: In epileptic disorders, EEG background activity is disorganized in or near the epileptogenic focus and spectral EEG analysis (SEA) can provide useful information about the focus. We tried to develop a new spectral index from basic spectral parameters to detect the epileptic abnormalities at EEG background activity. METHODS: A new spectral EEG index, epileptic abnormality index (EAI), was constructed from frequency band power and power asymmetry parameters. Within the index, parameters were weighted due to both conventional EEG knowledge and their power in discrimination healthy subjects from patients. EEG background activity from 99 epileptic patients and 146 healthy subjects was examined both by EAI and by a conventional SEA method, by using z-scoring statistic. Each test results were compared with visual EEG interpretation of subjects. RESULTS: In patient groups, EAI was most successful in lateralization of epileptic abnormalities. It was also helpful in discrimination of epileptic patients from normals in the case where visual EEG interpretation was 'normal'. CONCLUSIONS: EAI depends on basic spectral parameters and it combines statistical methods and clinical knowledge about EEG. It increases the analysis capacity of SEA in evaluation of EEG background activity. SIGNIFICANCE: EAI is a new and useful approach in detection of EEG background abnormalities in epilepsy and its logical base can also be used in the detection of brain electrical activity abnormalities other than epileptic disorders.

Accessory nerve function after modified radical and lateral neck dissections.

OBJECTIVES: Evaluate preoperative and postoperative electrophysiological changes related to the accessory nerve with reference to dissection technique, modified radical neck dissection, and lateral neck dissection. STUDY DESIGN: Prospective electrophysiological analysis of accessory nerve function in a total of 20 laryngeal carcinoma patients after neck dissection, 12 being lateral neck dissection (4 bilateral) and 8 being modified radical neck dissection. METHODS: Distal latencies, compound muscle action potentials, and electromyography findings were investigated before surgery and, in early and late postoperative periods in 20 laryngeal carcinoma patients. Results were evaluated by Student t test and chi2 test for intragroup and intergroup differences. RESULTS: In the lateral neck dissection group, postoperative distal latencies were longer, without statistical significance, whereas in the modified radical neck dissection group postoperative latencies were statistically longer. Postoperative compound muscle action potentials were significantly lower in both groups. Electromyographic work-up showed deterioration in early postoperative periods and improvement in late postoperative periods. When intergroup differences were compared, both postoperative compound muscle action potential and electromyographic findings were worse in the lateral neck dissection group. CONCLUSIONS: The accessory nerve function after modified radical neck dissection is better than function after lateral neck dissection because of increased stress applied to the nerve during retraction of the sternocleidomastoid muscle for achievement of a better exposed surgical field in lateral neck dissection.

Brain SPECT evaluation of patients with pure photosensitive epilepsy.

UNLABELLED: This study was performed to determine the utility of 99mTc-HMPAO brain SPECT in evaluating patients with pure photosensitive epilepsy. METHODS: Seven patients (2 boys, 5 girls), aged 8 to 15 yr (mean 11.1 +/- 2.5 yr), were studied. All patients underwent a detailed neurologic examination, interictal and ictal EEGs, CT and/or MRI and SPECT imaging. The baseline SPECT study was performed during the interictal period and the activation study was performed while the patients were having seizures provoked by watching television. RESULTS: The baseline SPECT study showed that six of seven patients had relatively hypoperfused regions in their frontal lobes that could involve the neighboring parietal and temporal regions. The activation study revealed that all seven patients had relative hyperperfusion in these brain regions that were relatively hypoperfused in the baseline study. The side-to-side asymmetry indexes for these visually-interpreted rCBF abnormalities ranged from 3% to 6%. CONCLUSION: The relatively consistent pattern of frontal rCBF alterations suggests that frontal lobe functions were implicated in the evolution of photosensitivity-related seizures in patients with pure photosensitive epilepsy.