Abstracts

Four patients admitted to the EMU for surgical evaluation were noted on MRI to have transient focal lesions in the splenium of the corpus callosum (SCC). This phenomenon was observed in patients who had a MRI on the last day of their admission. This has not been observed in our pt population who have had MRI[apos]s prior to admission or in any other outpatient situations. The etiology of this rare finding is currently unknown. The literature suggests that this occurrence may possibly be related to reversible demyelination, AED toxicity, frequent seizures and/or rapid taper of an AED. Our radiologists interpreted the initial MRI findings as suggestive of ischemic lesions, tumor or demyelinating disease. In all cases the lesion was not seen on repeat MRI. We reviewed the MRI scans, reports, and clinical data on four patients found to have a focal lesion in the splenium of the corpus callosum. Four patients (2 females/2males, 1 African American/3 Caucasian descent) ages 13-45 yrs old were admitted to the EMU. AED serum blood levels on admission included CBZ 9.7 and 8.3ug/mL; LMG 2.4ug/mL; OXC 19 and 6.5 ug/mL; and PHT 20.9ug/mL. AEDs were discontinued for an average of 5 days. 3 pts were on antidepressants. Average length of stay in hospital was 7.5 days. Each pt was sleep deprived twice. 2 pts experienced szs from the left hemisphere, 1 pt had szs from the right and one pt had non-epileptic events but also had interictal bursts of generalized sharp waves. 3 of the 4 initial MR images specifically were seen on the T2 weighted and DWI. images. 1 pt was started on TPM and 3 were started on LVT by the time the MRI was performed. Follow-up MRI was negative with regard to the lesion in the SCC in all 4 patients. Differential dx included TIA and transient demyelination. This study raised more questions than it answered. We concluded that the lesions are rare and transient. The cause of the transient lesions cannot be determined with the limited number of pts and the limited data available in the literature. One might ponder if the frequency or type of sz influences the occurrence; however, there was also one patient who had non-epileptic episodes. Could rapid removal of the medications and being off them for several days precipitate such a change? Could sleep deprivation cause such a phenomenon? Should we make sure that the MR scans are done prior to admission or later as an out-patient? (Supported by The Comprehensive Epilepsy Care Center For Children And Adults.)