Article
Memory localization with FMRI asking for famous names and cities for dominant temporal lobe surgery
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Authors
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Peter Grummich
- Universitätsklinik Erlangen, Neurochirurgische Klinik, Erlangen, Deutschland
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Karl Rössler
- Universitätsklinik Erlangen, Neurochirurgische Klinik, Erlangen, Deutschland
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Michael Buchfelder
- Universitätsklinik Erlangen, Neurochirurgische Klinik, Erlangen, Deutschland
| Published: | June 18, 2018 |
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Outline
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Objective: In cases of surgery in the dominant temporal lobe, special care has to be taken to sustain memory functions. Retrograde memory is distinguished in episodic memory and factual knowledge memory. After several surgeries a worsening of factual knowledge memory was observed. The Wada test examines the episodic memory and not factual knowledge. Therefore a new approach was taken to localize factual memory by FMRI.
Methods: For factual memory localization 3 paradigms were used: Remember cities, Remember person names, and multiplication results. 114 patients were measured during the City- paradigm. 85 were measured with the person name paradigm. Tasks were presented visually. During performing these tasks we measured brain activity with a 1.5T MR scanner with echo planar imaging (Sonata, Siemens Medical Solutions) using a block paradigm with 180 measurements in 6 blocks (rest alternating with activation, 25 slices, 3mm thickness & resolution TR=2470, TE=60). Correlation maps were calculated and merged with 3D-MR maps. Intraoperative MR-measurement was performed. Memory tests were performed preoperatively and postoperatively to investigate deficits in factual knowledge retrieval.
Results: In 138 patients factual knowledge activity was localized. Of these, 123 cases underwent surgery with the factual knowledge area included in the navigation. Only one had a permanent worsening of factual knowledge abilities after surgery. In this patient was shown by MRI that in spite of the area was in the plan it was resected during surgery. 3 patients had improvements of factual knowledge abilities compared to presurgical tests.
In 10 cases, where no presurgical measurement was performed and resection extended far back into the region where factual knowledge normally is found, only one had no deficit in recall of factual knowledge. This happened in spite of the Wada test, which did not indicate this impairment.
Conclusion: By integrating factual knowledge areas into the navigation plan and observing it during surgery it is possible to avoid worsening of this memory ability due to surgery. In certain cases even an improvement of factual knowledge can be achieved due to relief of compressed functional cortex.
