Brainstem injection of lidocaine releases the descending pain-inhibitory mechanisms in a rat model of mononeuropathy.

Lidocaine injections in the rostral ventromedial medulla (RVM) have been shown to produce significant reduction of neuropathic manifestations in rats. This effect has been attributed to selective block of a pain descending facilitatory system, responsible for chronic pain. However, recent observations from our laboratory did not provide confirmation to this hypothesis.

Alteration of GABAergic and glycinergic mechanisms by lidocaine injection in the rostral ventromedial medulla of neuropathic rats.

Attenuation of neuropathic manifestations in experimental animals, by lidocaine injection in the rostral ventro-medial medulla (RVM), has been traditionally attributed to selective block of a descending pain facilitatory system. However, the presence of descending fibers carrying this effect and the selective action of lidocaine on the facilitatory neurons, have not been supported by convincing experimental evidence. The present study aimed to investigate the mechanisms underlying the hypoalgesic action of lidocaine injection in the brainstem.