Article
Complex invasive monitoring for intractable epilepsy : experience and outcome in 120 patients
Komplexes invasives Monitoring bei therapierefraktärer Epilepsie : Erfahrungen und Ergebnisse bei 120 Patienten
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Published: | May 4, 2005 |
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Outline
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Objective
To evaluate the benefit and risk of complex invasive EEG monitoring with implanted electrodes in patients with refractory epilepsy.
Methods
Review of 651 consecutive patients, who underwent electrode implantation for invasive EEG monitoring between 1990 and 2003. 120 complex electrode implantations were defined as: 1. 66 combinations of multiple subdural strip and grid electrodes and 2. 28 additional depth electrodes 3. 7 combinations of grid and depth electrodes 4. 16 multiple interhemispheric strip electrodes with or without other electrodes. 531 procedures with standard combinations of temporal depth- and strip electrodes, and implantation of single electrode types were excluded.
Results
Procedures were completely uneventful in 71 patients (59%).15 patients (13%) had significant blood loss and anaemia. 23 patients (19%) showed minor morbidity, e.g. a small haematoma on a grid electrode. 9 patients (7.5%) had temporary major morbidity after electrode implantation, most of them due to larger grid haematomas, which required surgical intervention. 2 patients (1.7%) had persisting neurological deficits: one mild hemiparesis and one hemianopia. There were no deaths. In 13 patients no further epilepsy surgery was recommended: 3 patients (23%) improved gradually with new medication or vagus nerve stimulation. 107 of 120 patients (89%) were considered candidates for epilepsy surgery: 51 procedures (48%) were done in the frontal or fronto-central area: 23 patients had frontal lesionectomies only, 22 patients had lesionectomies plus multiple subpial transections (MST), while 6 had MST only. 34 procedures (32%) were mainly temporal: 24 lesionectomies, 8 lesionectomies plus MST and 2 MST only. 22 patients (20%) were operated in various other areas. 60 patients became seizure free (56% Engel I). 7 patients had rare seizures only (7% Engel II). 15 patients had a more than 75% improvement (14% Engel III), and 24 patients did not improve (22% Engel IV). Mean follow-up was 35 months.
Conclusions
Complex invasive monitoring enabled or supported epilepsy surgery in 89% of patients in this series and 63% attained satisfactory seizure control. The risks of these diagnostic tools should be noticed, especially a significant rate of temporary morbidity. However, the rate of permanent morbidity was only 1.7%.