C. Adam et al., VALUE OF MAGNETIC-RESONANCE-IMAGING - BASED MEASUREMENTS OF HIPPOCAMPAL FORMATIONS IN PATIENTS WITH PARTIAL EPILEPSY, Archives of neurology, 51(2), 1994, pp. 130-138
Objective: To determine the occurrence of magnetic resonance imaging-d
etected hippocampal atrophy (HA) in patients with partial epilepsy (te
mporal and extratemporal, cryptogenic, or symptomatic). Magnetic reson
ance imaging-detected HA has been demonstrated to be both sensitive an
d specific for hippocampal sclerosis in cryptogenic temporal lobe epil
epsy. Design: Patients' hippocampal formations were measured on a comp
uterized system using Tl-weighted, 5-mm contiguous magnetic resonance
coronal images made perpendicular to the hippocampus long axis. Hippoc
ampal atrophy was defined on the basis of a normative asymmetry index
and correlated with the epileptogenic focus defined by clinical, elect
roencephalographic, and magnetic resonance imaging (apart from HA) loc
alizing data. Patients and Control Subjects: Seventy patients with int
ractable complex partial seizures of temporal, extratemporal,or undefi
ned origin and 21 healthy control subjects. Results: Hippocampal atrop
hy was present in 70% of patients with cryptogenic temporal lobe epile
psy (TLE) (n=40), 44% of patients with symptomatic TLE (n=9), 29% of p
atients with extratemporal epilepsy (n=14), and 6% of unclassified pat
ients (n=16). In the cryptogenic TLE category, HA was marked and usual
ly concordant (93%) with electroencephalographic lateralization. Hippo
campal atrophy was often mild in the extratemporal epilepsy category.
With the use of a wider confidence interval (+/- 3.1 SD instead of +/-
2.2 SD), HA specificity for TLE increased to 93%, HA specificity for
lateralizing cryptogenic TLE reached 96%, and HA sensitivity for crypt
ogenic TLE stood almost unchanged (68%). We found a link between early
convulsions and HA occurrence. Conclusions: Hippocampal atrophy is a
marker for TLE. Dual pathologic findings are detected in 44% of sympto
matic TLE cases. Mild HA is rarely associated with extratemporal epile
psy. Magnetic resonance imaging-based hippocampal volumetric analysis
is a useful method to localize the origin of partial complex seizures.