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Updated: Mar 29, 2026
Anteromesial Temporal Lobectomy for Medically Intractable Temporal Lobe Epilepsy: An Operative Study
Published on: August 15, 2025
Relationship between remnant hippocampus and amygdala and memory outcomes after stereotactic surgery for mesial
Hana Malikova1, Lenka Kramska2, Zdenek Vojtech3
1Department of Radiology, Na Homolce Hospital, Prague, Czech Republic ; Institute of Anatomy, Second Medical Faculty, Charles University in Prague, Prague, Czech Republic.
Background And Purpose:
Mesial temporal structures play an important role in human memory. In mesial temporal lobe epilepsy (MTLE), seizure activity is generated from the same structures. Surgery is the definitive treatment for medically intractable MTLE. In addition to standard temporal lobe microsurgical resection, stereotactic radiofrequency amygdalohippocampectomy (SAHE) is used as an alternative MTLE treatment. While memory impairments after standard epilepsy surgery are well known, it has been shown that memory decline is not a feature of SAHE. The aim of the present study was to correlate the volume of the remnant hippocampus and amygdala in patients treated by SAHE with changes in memory parameters.
Materials And Methods:
Thirty-seven MTLE patients treated by SAHE (ten right, 27 left) were included. Patients underwent magnetic resonance imaging examinations including hippocampal and amygdalar volumetry and neuropsychological evaluation preoperatively and 1 year after surgery.
Results:
Using Spearman correlation analyses, larger left-sided hippocampal reductions were associated with lower verbal memory performance (ρ=-0.46; P=0.02). On the contrary, improvement of global memory quotient (MQ) was positively correlated with larger right-sided hippocampal reduction (ρ=0.66; P=0.04). Similarly, positive correlations between the extent of right amygdalar reduction and verbal MQ (ρ=0.74; P=0.02) and global MQ change (ρ=0.69; P=0.03) were found. Thus, larger right hippocampal and amygdalar reduction was associated with higher global and verbal MQ change after SAHE.
Conclusion:
Larger left-sided hippocampal reductions were associated with lower verbal memory performance. This finding is in accordance with the material-specific model of human memory, which states that the dominant hemisphere is specialized for the learning and recall of verbal information. We hypothesize that larger right-sided ablations enable the left temporal lobe to support memory more effectively, perhaps as a consequence of epileptiform discharges spreading from remnants of right mesiotemporal structures to the left.
Insights
Stereotactic radiofrequency amygdalohippocampectomy (SAHE) for mesial temporal lobe epilepsy (MTLE) showed that larger reductions in the right hippocampus and amygdala correlated with improved memory. However, greater left hippocampal reductions were linked to poorer verbal memory performance.
Area of Science:
- Neurosurgery
- Neurology
- Cognitive Neuroscience
Background:
- Mesial temporal structures are crucial for human memory.
- Mesial temporal lobe epilepsy (MTLE) originates in these memory-related structures.
- Stereotactic radiofrequency amygdalohippocampectomy (SAHE) is an alternative surgical treatment for intractable MTLE, with memory decline not being a typical outcome.
Purpose of the Study:
- To investigate the relationship between the volume of remnant hippocampus and amygdala after SAHE and memory changes.
- To correlate post-SAHE remnant volumes with specific memory parameter alterations in MTLE patients.
Main Methods:
- Magnetic resonance imaging (MRI) for hippocampal and amygdalar volumetry.
- Neuropsychological evaluations preoperatively and 1 year post-surgery.
- Spearman correlation analysis applied to 37 MTLE patients treated with SAHE.
Main Results:
- Larger left hippocampal reductions correlated with lower verbal memory performance (ρ=-0.46; P=0.02).
- Greater right hippocampal reduction was associated with improved global memory quotient (MQ) (ρ=0.66; P=0.04).
- Increased right amygdalar reduction positively correlated with verbal MQ (ρ=0.74; P=0.02) and global MQ change (ρ=0.69; P=0.03).
Conclusions:
- Greater reduction in the right hippocampus and amygdala after SAHE is linked to better global and verbal memory outcomes.
- Significant left hippocampal reduction is associated with diminished verbal memory, supporting the material-specific model of memory.
- Hypothesized that larger right-sided ablations may enhance left temporal lobe memory function, potentially by reducing epileptiform discharge spread.
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