Neuromagnetic Localization of [dsquote]Re-Build-Up[dsquote] Discharges Corresponds to Ischemic Symptom in Patients with Moyamoya Disease.
Abstract number :
1.234
Submission category :
Year :
2001
Submission ID :
200
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
N. Nakasato, M.D., Ph.D., Neurosurgery, Kohnan Hospital, Sendai, Japan; K-I. Nagamatsu, M.D., Neurosurgery, Tohoku University, Sendai, Japan; A. Kanno, Ph.D., MEG Laboratory, Kohnan Hospital, Sendai, Japan; M. Iwasaki, M.D., Neurosurgery, Tohoku Universit
RATIONALE: Moyamoya disease is a progressive stenosis of bilateral carotid arteries due to unknown etiology. [dsquote]Re-build-up[dsquote] phenomenon, abnormal slow wave induced by hyperventilation (HV), is a characteristic finding on electroencephalogram (EEG) in patients with moyamoya disease especially in children. Re-build-up is also known to have close correlation with cerebral ischemic symptoms. Mechanism or generator location of re-build-up, however, remains unknown.
METHODS: We measured magnetoencephalography (MEG) over the entire head (Neuromag122, 4D Neuroimaging, San Diego) in three patients with moyamoya disease. Both EEG and MEG were measured simultaneously in a magnetically shielded room. We also measured somatosensory evoked fields for median nerve stimulus and auditory evoked fields for tone bursts. Sources of the evoked responses were used as physiological landmarks of cortical mapping.
RESULTS: During a period of HV for 1 to 2 minutes no patient indicated abnormal neurological symptoms. Slow wave discharges appeared during HV (build-up phenomenon), but they indicated no lateralization in either EEG or MEG. A few minutes after the end of HV, all patients indicated abnormal slow waves which had more lateralized distribution in MEG than in EEG (re-build-up), with or without transient ischemic symptoms. Isofield MEG maps indicated clear dipole patterns of the re-build-up discharges. Source localization by a current dipole model indicated the cortical area that could explain the habitual symptom of transient ischemic attacks in each patient. Figure shows a case of Moyamoya disease (A: left carotid angiography). A few minutes after the end of HV, the patient had right hand motor weakness and re-build-up discharges in MEG (B: a dipole pattern in isofield map; C: dipole localization near the left central sulcus).
CONCLUSIONS: Neuromagnetic localization of abnormal discharges may indicate responsible cortical area for ischemic symptoms with high spatial and temporal resolution. MEG with HV may be useful for decision making before revasucularization surgery in patients with moyamoya disease.[figure]
Support: Grant-in-Aid for the Development of Innovative Technology No.
12208 from the Ministry of Education, Culture, Sports, Science and
Technology of Japan.