Intrathecal baclofen for dystonia of complex regional pain syndrome

Abstract

Dystonia in complex regional pain syndrome (CRPS) responds poorly to treatment. Intrathecal baclofen (ITB) may improve this type of dystonia, but information on its efficacy and safety is limited. A single-blind, placebo-run-in, dose-escalation study was carried out in 42 CRPS patients to evaluate whether dystonia responds to ITB. Thirty-six of the 38 patients, who met the responder criteria received a pump for continuous ITB administration, and were followed up for 12 months to assess long-term efficacy and safety (open-label study). Primary outcome measures were global dystonia severity (both studies) and dystonia-related functional limitations (open-label study). The dose-escalation study showed a dose-effect of baclofen on dystonia severity in 31 patients in doses up to 450 microg/day. One patient did not respond to treatment in the dose-escalation study and three patients dropped out. Thirty-six patients entered the open-label study. Intention-to-treat analysis revealed a substantial improvement in patient and assessor-rated dystonia scores, pain, disability and quality-of-life (Qol) at 12 months. The response in the dose-escalation study did not predict the response to ITB in the open-label study. Eighty-nine adverse events occurred in 26 patients and were related to baclofen (n=19), pump/catheter system defects (n=52), or could not be specified (n=18). The pump was explanted in six patients during the follow-up phase. Dystonia, pain, disability and Qol all improved on ITB and remained efficacious over a period of one year. However, ITB is associated with a high complication rate in this patient group, and methods to improve patient selection and catheter-pump integrity are warranted.

Clinical features and pathophysiology of complex regional pain syndrome

“…106–109 As to what those mechanisms are is not well understood, but enhancement of spinal inhibitory neurotransmission by intrathecal administration of the γ-aminobutyric-acid-receptor-B (GABA B ) agonist baclofen but not glycine, improved dystonia. 110,111 Thus, it seems likely that spinally mediated GABA-ergic mechanisms play a specific role in the dystonia associated with CRPS. 110,111 …”

“…110,111 Thus, it seems likely that spinally mediated GABA-ergic mechanisms play a specific role in the dystonia associated with CRPS. 110,111 …”

Complex regional pain syndrome: a recent update

“…Calcium-channel blockade with nifedipine has been reported to be effective in managing the vasoconstriction occurring in this phase of CRPS [76, 79]. Additionally, the use of gamma-aminobutyric acid-β (GABA) agonist such as baclofen has also been effective in reducing dystonia and pain while improving functionality and quality of life in patients with chronic CRPS [80–82]. A recent study looking into combined neuromodulation with baclofen as an adjunct to spinal cord stimulation (SCS) therapy demonstrated effectiveness in decreasing pain intensity and dystonia, suggesting the need for further larger scale trials [83].…”

Current and Future Issues in the Development of Spinal Agents for the Management of Pain

“…Baclofen, the clinically approved GABA-B agonist, has potent stereospecific suppressive effects upon motor tone [253] and is widely used clinically to regulate motor tone in the case of spasticity [254-256]; but it has also been implicated in having suppressive effects upon nociceptive processing after intrathecal delivery in preclinical models of facilitated processing [217] and hyperpathia in mono and polyneuropathies and spinal injury [220, 221, 257-259] and in humans [260, 261]. …”