Modulation of pain perception by neuronavigated repetitive transcranial magnetic stimulation (rTMS) of the cerebellum

Background:

Chronic pain syndromes often constitute a therapeutic dilemma characterized by drug resistance or abuse of pain relievers like opiods while pain relief is most often unsatisfactory in these patients. Frequently, the course of the disease ends up in disablement. Therefore, development of new therapeutic strategies are necessary.

In the last years, many studies have contributed to a better understanding of the underlying neurobiological processes involved in pain perception. According to this concept, a complex cortical-subcortical network called „pain neuromatrix“ is involved in pain processing (1). Based on the fact that the thalamus plays a crucial role within this network, modulation of thalamic processing should alter pain sensation.

Repetitive transcranial magnetic stimulation (rTMS) has been shown to be able to modulate neuronal activity in distributed neuronal networks. Furthermore, cerebellar stimulation allows to modulate motor cortex excitability, which seems to be conveyed by modulation of thalamic activity (2;3). The aim of the current study was to determine, whether rTMS of the cerebellum allows to modulate pain sensation in healthy adults.

Material and Methods:

Sensory thresholds for warm and cold sensation and pain have been determined by means of a quantitative sensory analyser (TSA; Medoc; Israel) before and after high (10Hz) and low (1Hz) frequency neuronavigated rTMS of the cerebellum (1000 stimuli, 120% resting motor threshold) in 4 adult healthy volunteers.

Results: Cerebellar stimulation led to alteration of sensory thresholds and attenuation of cold pain sensation.

Conclusion: These preliminary results suggest that rTMS of the cerebellum is a promising tool for the modulation of pain sensation. Further studies are needed to explore the potential of cerebellar rTMS for the treatment of chronic pain states.

References:

(1) Melzack R. Pain and the neuromatrix in the brain. J Dent Educ 2001; 65:1378.

(2) Oliveri M. et al. Increased facilitation of the primary motor cortex following 1Hz repetitive transcranial magnetic stimulation of the contralateral cerebellum in normal humans. Neurosci Lett 2005; 376:188.

(3) Daskalakis ZJ. et al. Exploring the connectivity between the cerebellum and motor cortex in humans. J Physiol 2004; 557(Pt 2):689.