[The predictive lidocaine test in treatment of neuropathic pain]

In daily practice, the intravenous lidocaine drip has been introduced as a predictive test for subsequent oral treatment with adjuvant drugs (anti-depressants, channel blockers and anti-convulsants). Our aim is the assessment of the correlation between the test response and the effectiveness of the consequent oral drug therapy.

183 inpatients (central and peripheral neuropathic pain), treated between 1996-1997, were retrospectively checked. The trial was conducted as follows: a VAS reading > 5 was taken; a subsequent continuous i.v. lidocaine drip was given, at a dose of 4 mg/kg, in saline solution; a VAS reading was taken before (VAS 0), every 5 minutes, and at the end of the drip (VAS 1); the results of the drip were to be considered positive where pain relief was > or = 50%; irrespective of test results, all patients were given a different follow-up drug therapy; a VAS reading was taken one month after the drug therapy (VAS 2).

Eighty-five patients (90%), responders to lidocaine, had a pain relief and 71 patients (85%), no responders to lidocaine, did not have improvement by taking oral drugs.

In agreement with a other authors, we also noted that there was a statistically significant correlation between the results obtained and the therapy prescribed; the usefulness of a lidocaine drip as routine procedure to predict the therapeutic response of neuropathic pain to adjuvant analgesics is underlined.