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Hippocampal sclerosis: correlation of MR imaging findings with surgical outcome
1Department of Radiology, Seoul National University College of Medicine, Seoul, Korea.
Objective:
Atrophy and a high T2 signal of the hippocampus are known to be the principal MR imaging findings of hippocampal sclerosis. The purpose of this study was to determine whether or not individual MRI findings correlate with surgical outcome in patients with this condition.
Materials And Methods:
Preoperative MR imaging findings in 57 consecutive patients with pathologically-proven hippocampal sclerosis who underwent anterior temporal lobectomy and were followed-up for 24 months or more were retrospectively reviewed, and the results were compared with the postsurgical outcome (Engel classification). The MR images included routine sagittal T1-weighted and axial T2-weighted spin-echo images, and oblique coronal T1-weighted 3D gradient-echo and T2-weighted 2D fast spin-echo images obtained on either a 1.5 T or 1.0 T unit. The images were visually evaluated by two neuroradiologists blinded to the outcome; their focus was the presence or absence of atrophy and a high T2 hippocampal signal.
Results:
Hippocampal atrophy was seen in 96% of cases (55/57) [100% (53/53) of the good outcome group (Engel class I and II), and 50% (2/4) of the poor outcome group (class III and IV)]. A high T2 hippocampal signal was seen in 61% of cases (35/57) [62% (33/53) of the good outcome group and 50% (2/4) of the poor outcome group]. All 35 patients with a high T2 signal had hippocampal atrophy. 'Normal' hippocampus, as revealed by MR imaging, occurred in 4% of patients (2/57), both of whom showed a poor outcome (Engel class III). The presence or absence of hippocampal atrophy correlated well with surgical outcome (p<0.01). High T2 signal intensity did not, however, significantly correlate with surgical outcome (p>0.05).
Conclusion:
Compared with a high T2 hippocampal signal, hippocampal atrophy is more common and correlates better with surgical outcome. For the prediction of this, it thus appears to be the more useful indicator.
Insights
Hippocampal atrophy on MRI is a better predictor of successful epilepsy surgery outcomes than high T2 signal intensity. This finding aids in surgical planning for patients with hippocampal sclerosis.
Area of Science:
- Neurology
- Radiology
- Neurosurgery
Background:
- Hippocampal sclerosis is characterized by hippocampal atrophy and high T2 signal on MRI.
- Predicting surgical outcomes in these patients is crucial for treatment planning.
Purpose of the Study:
- To evaluate the correlation between individual MRI findings (atrophy and high T2 signal) and surgical outcomes in patients with hippocampal sclerosis.
Main Methods:
- Retrospective review of preoperative MRI scans from 57 patients with pathologically confirmed hippocampal sclerosis who underwent anterior temporal lobectomy.
- Visual evaluation of atrophy and high T2 signal by blinded neuroradiologists, correlated with postsurgical outcomes (Engel classification).
Main Results:
- Hippocampal atrophy was present in 96% of cases and strongly correlated with good surgical outcomes (p<0.01).
- High T2 signal was observed in 61% of cases but did not significantly correlate with surgical outcome (p>0.05).
- Patients with a 'normal' hippocampus on MRI had poor surgical outcomes.
Conclusions:
- Hippocampal atrophy is a more common and reliable MRI indicator of favorable surgical outcomes in hippocampal sclerosis compared to high T2 signal.
- MRI-detected hippocampal atrophy is a valuable tool for predicting surgical success.