Contralateral treatment with lidocaine reduces spinal neuronal activity in mononeuropathic rats.

In anaesthetised and paralysed rats with chronic constriction of the sciatic nerve, the effects of subcutaneous contralateral lidocaine (100 microl) on the activity of lumbar (L(4)-L(5)) wide dynamic range neurons ipsilateral to the constriction have been investigated. The results show reduction of the spontaneous hyperactivity for 60 min; suppression or reduction of the responses to contralateral noxious stimulation for 60 min; lack of effect on the responses to ipsilateral noxious stimulation, except for the afterdischarge duration, reduced for 60 min. The finding that the altered neuronal activity following peripheral nerve injury associated to behavioural signs of neuropathic pain, can be reduced by contralateral treatment, may provide further suggestions to neuropathic pain mechanisms and management.