UTILITY OF REPEAT MRI IN EVALUATION OF PATIENTS FOR EPILEPSY SURGERY
Abstract number :
3.151
Submission category :
Year :
2002
Submission ID :
866
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Clifford Lamptey, Kevin Murphy, Mary Fitzsimons, Jack Phillips, Norman Delanty. Department of Clinical Neurological Sciences, Royal College of Surgeons of Ireland, Beaumont Hospital, Dublin 9, Ireland; National Department of Neurosurgery, Beaumont Hospita
RATIONALE: Repeat MRI may give useful information in individuals undergoing evaluation for epilepsy surgery. Most patients with intractable partial epilepsy referred to an epilepsy surgery centre will already have had a brain MRI, some of whose scans will have been reported as normal. Prior studies have shown that detection of a focal lesion by MRI is a favourable prognostic variable in the evaluation of patients with intractable partial epilepsy when concordant with clinical, electro-encephalographic, and neuropsychological information.
METHODS: The Epilepsy Surgery Unit at Beaumont Hospital, Dublin, is the national referral centre for patients with intractable partial epilepsy undergoing presurgical assessment in Ireland. We retrospectively evaluated whether repeat brain MRI provided useful additional information in the cohort of patients monitored with video EEG as part of a standard non-invasive evaluation for possible surgery at Beaumont Hospital from July 1999 to June 2001.
RESULTS: In total, fifty-four patients underwent a pre-surgical evaluation with video EEG monitoring over this time period. Of these fifty-four, twenty-three (43%) had had more than one MRI. In these twenty-three patients, new information was obtained from the later scan in eleven (48%) patients. This new information subsequently influenced the surgical decision making process in ten patients. Many patients who were originally reported to have had a normal initial scan were found to have a focal abnormality (including mesial temporal sclerosis) on subsequent imaging. Possible reasons for discrepancy between initial and subsequent scans include progression of disease, failure to acquire appropriate imaging sequences in the initial scan, and intra- and inter-observer variability.
CONCLUSIONS: Repeat imaging with a tailored epilepsy-protocol MRI frequently reveals structural abnormalities associated with intractable epilepsy which are often not appreciated on initial imaging. Repeat MRI should be considered in some patients with previously reported normal scans who otherwise appear to be good surgical candidates.