Motor cortex stimulation improves local cerebral glucose metabolism in the ipsilateral thalamus in patients with poststroke pain: case report.

BACKGROUND AND IMPORTANCE

Motor cortex stimulation (MCS) is documented as an effective therapeutic option for patients with poststroke pain. However, its underlying mechanism is still unclear. This study aimed to evaluate local cerebral glucose metabolism before and after MCS in patients with poststroke pain.

CLINICAL PRESENTATION

Using 18F-fluorodeoxyglucose positron emission tomography, cerebral metabolic rate for glucose (CMRGlu) was measured in 6 patients with poststroke pain before MCS. Their lesions were located in the corona radiata, internal capsule, and thalamus. An epidural electrode was implanted under the monitoring of intraoperative neuronavigation and somatosensory evoked/motor evoked potentials. 18F-fluorodeoxyglucose positron emission tomography was repeated in 4 patients (67%) who underwent successful MCS. Asymmetry of CMRGlu was semiquantitatively analyzed using an automated region of interest setting method. Before MCS, the ratio of CMRGlu in the ipsilateral to contralateral thalamus was 0.81 ± 0.13 (n = 6), (range, 0.63-0.97). However, there was no significant asymmetry of CMRGlu in other regions. Successful MCS significantly improved the asymmetry of CMRGlu in the ipsilateral thalamus from 0.81 ± 0.14 to 0.89 ± 0.17 (P < .01, n = 4). The therapeutic effect was proportional to the improvement of CMRGlu asymmetry (R = 0.79, P = 0.28; single regression analysis).

CONCLUSION

Poststroke pain is closely related to the reduced glucose use in the thalamus contralateral to the painful area. Successful MCS significantly improves glucose use in the thalamus ipsilateral to MCS, suggesting that electrical stimulation of the motor cortex may activate the corticothalamic connection from the motor cortex.