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Role of magnetic resonance imaging for preoperative
evaluation of patients with refractory epilepsy
ACF Hui, JMK Lam, YL Chan,
KM Au-Yeung, KS Wong, R Kay, WS Poon
Division of Neurology, Department of Medicine, The Chinese University
of Hong Kong, Prince of Wales Hospital
OBJECTIVE. To investigate the magnetic resonance
imaging characteristics of patients with refractory epilepsy and
the relationship to progression to surgery.
DESIGN. Prospective observational study.
SETTING. University teaching hospital, Hong Kong.
PATIENTS. Patients undergoing preoperative evaluation
for epilepsy surgery.
MAIN OUTCOME MEASURE. Cranial magnetic resonance
imaging findings, correlation with electroencephalographic results,
and percentage of patients who were considered suitable candidates
for surgery.
RESULTS. Structural abnormalities associated with refractory epilepsy
in 100 consecutive patients were mesial temporal sclerosis (30%),
neocortical sclerosis (23%), vascular malformation (7%), neuronal
migration disorders (7%), and tumours (5%). Normal brain scans were
found for 28% of patients. Fourteen of 30 (46%) patients with medial
temporal lobe lesions at magnetic resonance imaging were suitable
candidates for surgery compared with 8/42 (19%) patients with extrahippocampal
lesions (odds ratio=3.7; 95% confidence interval, 1.3-10.6; P<0.012).
CONCLUSION. Mesial temporal sclerosis was the most
common pathology in patients with refractory epilepsy. At the Prince
of Wales Hospital, for patients who have undergone a basic magnetic
resonance imaging protocol and surface electroencephalography, the
result of cranial magnetic resonance imaging is an important determinant
for whether patients will undergo surgery.
Hong Kong Med J 2003;9:20-4
Key words: Epilepsy; Magnetic resonance imaging;
Surgery
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