Learning objectives
The aim is to demonstrate practical steps for the potential of fMRI to lateralise memory functions as a replacement for the WADA test,
usingthe Home Town Walking Paradigm.
Background
Anterior temporal lobectomy is an effective therapy for refractory medial temporal lobe epilepsy but may significantly damage memory.
Patients with refractory epilepsy who may undergo temporal lobe surgery need precise information about their postoperative memory prospects.
Historically,
the prediction of potential postoperative memory deficits was based on neuropsychological measures and the Wada test.
This involves an invasive procedure involving cerebral angiogram and intra-carotid injection of 140 mg of sodium amytal.
Language and memory are assessed while hemiplegia persists.
fMRI has substantial potential to lateralize memory...
Findings and procedure details
Patients
We performed 55 memory fMRI from January 2014 to December 2016 by using the Home Town Walking Paradigm in temporal lobe epilepsy (n=26),
temporal lobe tumours (n=21) and vascular malformations (n=8).
Sequences
The fMRI is performed on two consecutive days with a block design,
requiring mental navigation through one’s hometown by using landmarks given by patients themselves.
An EPI sequence was used with TR 3000ms,
TE 30ms,
in-plane resolution 3.9mm (64x64 matrix,
FOV 250 mm),
slice thickness 3mm (gap 25%) and 10 sets of...
Conclusion
The practical steps of performing the 'Home Town Walk' memory fMRI paradigm in the clinical setting have been described.
It has produced consistent results andhas replaced the WADA test in our clinical practice.
For optimum results,good patient briefing and meticulous preparation is required.
References
Sidhu MK,
Stretton J,
Winston GP,
et al.
Memory fMRI predicts verbal memory decline after anterior temporal lobe resection.
Neurology.
2015;84(15):1512-9.
Towgood K,
Barker GJ,
Caceres A,
et al.
Bringing memory fMRI to the clinic: comparison of seven memory fMRI protocols in temporal lobe epilepsy.
Hum Brain Mapp.
2015;36(4):1595-608.