Analgesic effect of intrathecal baclofen bolus on neuropathic pain in spinal cord injury patients

Abstract

Background: GABA-ergic neurons are widely distributed throughout the central nervous system, including the spinal cord which is important for the transmission of pain impulses to the brain. Here we hypothesized that intrathecal baclofen (ITB) which is a GABA analogue might exert analgesic effects on neuropathic pain, which could be related to subtypes of pain in spinal cord injury (SCI).

Methods: SCI patients with a cervical or thoracic lesion and neuropathic pain were randomized to receive either a single ITB bolus or placebo. Numerical Rating Scale (NRS), Neuropathic Pain Symptom Inventory (NPSI), and Brief Pain Inventory (BPI) were obtained for assessment of neuropathic pain. Spasticity was assessed using Modified Ashworth Scale and visual analogue scale. Evaluations were performed at baseline, and 4, 8, and 24 h after application of ITB or placebo.

Result: Eight patients received ITB, 5 placebo. Neuropathic pain improved significantly in the ITB group based on NRS, BPI, and NPSI, which revealed an effect on all subtypes of pain. Spasticity declined significantly. In the placebo group, there was neither significant change in pain nor in spasticity.

Conclusion: An ITB bolus exerted a significant analgesic effect on all subtypes of neuropathic pain in SCI patients.

Significance: ITB has analgesic effects on all subtypes of neuropathic pain and can improve interference of neuropathic pain with activities of daily living. ITB might be a promising analgesic treatment to control neuropathic pain.

Keywords: Analgesic effect; Intrathecal baclofen bolus; Neuropathic pain; Spinal cord injury; Subtypes of pain.