Cryptogenic Temporal Lobe Epilepsy with Minimal Hippocampal Injury: A New Clinical-Pathologic Entity with Post-Surgery Seizure Control.
Abstract number :
L.04
Submission category :
Year :
2001
Submission ID :
1197
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
V.M. Andre, PhD, Neurobiology of Epilepsy, UCLA, Los Angeles, CA; D. Mendoza, BS, Neurobiology of Epilepsy, UCLA, Los Angeles, CA; G. Ojemann, MD, Neurosurgery, University of Washington, Seattle, WA; D. Born, MD, PhD, Neuropathology, University of Washing
RATIONALE: Surgically treated TLE is classified into patients with hippocampal sclerosis (HS), lesions, and cryptogenic cases (non-HS; non-lesional). In cryptogenic cases, post-surgery seizure control is generally less, but some patients achieve seizure control. We hypothesized that cryptogenic TLE patients with post-surgery seizure control would show subtle non-sclerotic hippocampal histopathologic changes compared with cryptogenic cases without seizure control.
METHODS: Surgically removed hippocampi from intractable cryptogenic TLE cases (n=21) were studied for cell counts and neo-Timm[scquote]s histochemistry. These patients showed no hippocampal atrophy or temporal lesion on MRI, and at least 6 months post-surgery were grouped into seizure free (n=12) versus not seizure free (n=9), and compared with autopsy specimens (n=19).
RESULTS: None of the cryptogenic cases showed histological signs of HS. Compared with autopsy cases and cryptogenic TLE cases that were not seizure-free, the cryptogenic seizure-free group showed a slight but significant decreased CA4 neuronal densities (20%; P=0.007) while the granule cell, polymorph, subgranular hilar layer and the Ammon[scquote]s horn pyramidal cell densities were not decreased. Furthermore, there was greater neo-Timm[scquote]s staining in the inner molecular layer in the seizure-free cryptogenic TLE cases compared with the cryptogenic cases that were not seizure controlled (P[lt]0.01).
CONCLUSIONS: This study shows that 57% of patients with cryptogenic TLE can become seizure free post-surgery, and this group was associated with mild selective CA4 cell loss and mossy fiber sprouting. The CA4 damage was different from end folium sclerosis and was not detectable by MRI or by qualitative histopathology. Therefore, the subtle CA4 cell loss might be the minimal damage sufficient to induce TLE, and would suggest a distinct clinical-pathologic group amendable for surgical therapy.
Support: PO1 NS 02808 and RO1 NS 38992