Positron emission tomography during motor cortex stimulation for pain control.
We studied regional changes in cerebral flood flow (rCBF) in 9 patients undergoing motor cortex stimulation (MCS) for pain control. Significant increase in rCBF was observed in the lateral thalamus ipsilateral to MCS probably reflecting corticothalamic connections from motor/premotor areas. Subsignificant increases were observed in the anterior cingulate, left insula and upper brainstem. Mean rCBF in the anterior cingulate increased during MCS in patients with good analgesic efficacy, while it decreased in those with poor clinical outcome; conversely, thalamic rCBF increased in the two groups, albeit to a greater extent in patients with good clinical results. Our results support a model of MCS action whereby activation of thalamic nuclei directly connected with motor and premotor cortices would entail a cascade of synaptic events in other pain-related structures, including the anterior cingulate and the periaqueductal gray. MCS could influence the affective-emotional component of chronic pain by way of cingulate activation, and lead to descending inhibition of pain impulses by activation of the brainstem. Such effects may be obtained only if thalamic activation reaches a 'threshold' level, below which the analgesic cascade would not be successfully triggered.
García-Larrea
L
L
CERMEP (Positron Emission Tomography Center), Lyon, France.
Peyron
R
R
Mertens
P
P
Grégoire
M C
MC
Lavenne
F
F
Bonnefoi
F
F
Mauguière
F
F
Laurent
B
B
Sindou
M
M
D000328:Adult; D001921:Brain / Q000098:blood supply* / Q000000981:diagnostic imaging; D001933:Brain Stem / Q000098:blood supply / Q000000981:diagnostic imaging; D004599:Electric Stimulation Therapy; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006179:Gyrus Cinguli / Q000098:blood supply / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D010104:Oxygen Radioisotopes; D059408:Pain Management; D017288:Pain Threshold / Q000502:physiology; D012039:Regional Blood Flow; D013788:Thalamus / Q000098:blood supply / Q000000981:diagnostic imaging; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome; D014867:Water
D010104:Oxygen Radioisotopes; D014867:Water