Hippocampal cell density and subcortical metabolism in temporal lobe epilepsy.
OBJECTIVE
Correlations between hippocampal cell density and subcortical metabolism in patients with temporal lobe epilepsy (TLE) were studied to explore possible links between subcortical function and the regulation of hippocampal excitability.


METHODS
Resected hippocampal cell densities were correlated with cortical and subcortical regional cerebral metabolic rate for glucose (CMRglu), as measured by [18F]-fluorodeoxyglucose positron emission tomography (18-FDG-PET), in 39 patients with intractable TLE who underwent anterior temporal lobectomy (ATL). CMRglu was measured ipsilateral and contralateral to the resected temporal lobe. Linear regression techniques were used for statistical analysis.


RESULTS
Hilar cell densities correlated positively and significantly with CMRglu in the bilateral thalamus, putamen and globus pallidus, and the ipsilateral caudate. Dentate granule cell densities correlated positively and significantly with CMRglu in the bilateral thalamus and putamen. There was no significant correlation between cell densities and CMRglu in any cortical region, including the hippocampus.


CONCLUSIONS
We postulate that hippocampal cell loss results in decreased efferent synaptic activity to the thalamus and basal ganglia, causing decreased neuronal activity in these structures with consequent hypometabolism. This synaptic activity has a significant bilateral component. Subcortical hypometabolism in patients with TLE may reinforce the epileptogenic potential of mesial temporal lobe discharges.
Dlugos
D J
DJ
Division of Neurology, Children's Hospital of Philadelphia, PA 19104, USA.
Jaggi
J
J
O'Connor
W M
WM
Ding
X S
XS
Reivich
M
M
O'Connor
M J
MJ
Sperling
M R
MR
D000679:Amygdala / Q000000981:diagnostic imaging / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002421:Caudate Nucleus / Q000000981:diagnostic imaging / Q000378:metabolism; D002452:Cell Count; D004833:Epilepsy, Temporal Lobe / Q000000981:diagnostic imaging* / Q000378:metabolism; D019788:Fluorodeoxyglucose F18; D005917:Globus Pallidus / Q000000981:diagnostic imaging / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology* / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging; D011699:Putamen / Q000000981:diagnostic imaging / Q000378:metabolism; D012044:Regression Analysis; D014055:Tomography, Emission-Computed
D019788:Fluorodeoxyglucose F18; D005947:Glucose