Intrathecal Baclofen (ITB) Bolus on Neuropathic Pain (NP). Preliminary Study.

Effect of Intrathecal Baclofen (ITB) Bolus on Neuropathic Pain (NP) in Spinal Cord Injury (SCI) Patients. Preliminary Study.

Hypothesis:

ITB bolus can have antinociceptive effect on neuropathic pain in spinal cord injury patients, which could depend on the subtype of pain, or on the lesion level, cervical or thoracic spinal cord injury.

Objective:

To study the effect of intrathecal baclofen bolus on neuropathic pain in patients with spinal cord injury at cervico-dorsal level.

Primary Endpoint:

Effect of intrathecal baclofen bolus in neuropathic pain (measured using the Neuropathic Pain Inventory Scale, the Brief Pain Inventory and the Numerical Rating Scale) in spinal cord injury at cervico-dorsal level.

Secondary Endpoints:

1. Spasticity and spasms (measured using the Modified Ashworth Scale and the Visual Analogue Scale and Penn Spasm Frequency Scale).
2. Neurophysiological examination (warm perception threshold, heat pain perception threshold, evoked pain perception and contact heat evoked potentials).

The study will be a randomized, double-blind (patients and who will realize the clinical and neurophysiologic evaluation), placebo-controlled trial. We will recruit 10-12 patients with SCI with complete or incomplete lesion at cervical or thoracic level to be randomly distributed in two study groups: ITB bolus group and a placebo group.

In 6-8 months, we will administer an intrathecal baclofen bolus of 50 µg (1ml) in 5-6 SCI patients or 1ml of physiologic serum subcutaneously in the other 5-6 SCI patients.

Before the intrathecal baclofen or placebo bolus is administered, patients will be evaluated for neuropathic pain, using the Neuropathic Pain Inventory Scale, Brief Pain Inventory and Numerical Rating Scale. Spasticity and spasms will also be measured by the Modified Ashworth Scale, the Visual Analogue Scale and the Penn Spasm. After that, patients will also undergo, early in the morning when the intrathecal baclofen or placebo bolus will be administered, a neurophysiology assessment (warm perception threshold, heat pain perception threshold, evoked pain perception and contact heat evoked potentials).

After the neurophysiological evaluation, patients will receive an intrathecal baclofen bolus of 50 µg or placebo (randomization). After the intrathecal baclofen or placebo injection, a clinical and neurophysiological examination, of neuropathic pain and spasticity and spasms, will be repeated at 1, 2 and 4 hours after the bolus administration. Moreover, Kumru et al. (2013) reported that the 50 µg intrathecal baclofen bolus reduced the pain perception threshold and evoked acute pain perception in patients with SCI.

During all evaluation period, the patients continue with their analgesic, antispastic and/or any other stable medication.

Inclusion Criteria:

• Age between 18-70 years and at least one year since the spinal cord injury.
• Aetiology: stable SCI from traumatic or medical origin.
• Patients with chronic refractory neuropathic pain and with spinal cord injury, both complete and incomplete, at the cervico-thoracic level.
• Severity of pain equal or greater than 4 in the Numerical Rating Scale.
• With spasticity (MAS>=).
• Stable analgesic, antispastic and any other medication.

Exclusion Criteria:

• Patients who do not give patient inform consent.
• Contraindication for baclofen or intrathecal injection.