Oral capsules of tetra-hydro-cannabinol (THC), cannabidiol (CBD) and their combination in peripheral neuropathic pain treatment.

BACKGROUND: Cannabinoids are often prescribed for neuropathic pain, but the evidence-based recommendation is 'weak against'. OBJECTIVES: The aim was to examine the effect of two cannabinoids and their combination in peripheral neuropathic pain. METHODS: This was a randomized, double-blind, trial with treatment arms for cannabidiol (CBD), tetra-hydro-cannabinol (THC), CBD and THC combination (CBD/THC), and placebo in a 1:1:1:1 ratio and flexible drug doses (CBD 5-50 mg, THC 2.5-25 mg, and CBD/THC 5 mg/2.5 mg-50 mg/25 mg). Treatment periods of 8-week duration were proceeded by 1 week for baseline observations. Patients with painful polyneuropathy, post-herpetic neuralgia and peripheral nerve injury (traumatic or surgical) failing at least one previous evidence-based pharmacological treatment were eligible for inclusion. The primary outcome was the change in weekly average of daily pain measured with a numeric rating scale (NRS). Trail Making Test (TMT) was used as one of the tests of mental functioning. RESULTS: In all, 145 patients were included in the study of which 118 were randomized and 115 included in the intention-to-treat analysis. None of the treatments reduced pain compared to placebo (p = 0.04-0.60). Effect sizes as estimated in week 8 (positive values worse and negative better than placebo) were CBD mean 1.14 NRS points (95% CI 0.11-2.19), THC 0.38 (CI -0.65 to 1.4) and CBD/THC -0.12 (-1.13 to 0.89). CONCLUSIONS: CBD, THC and their combination did not relieve peripheral neuropathic pain in patients failing at least one previous evidence-based treatment for neuropathic pain.

MRI of the central nervous system in MS patients with and without pain.

BACKGROUND: Central pain (CP) is a common symptom in MS. Multiple theories are present about the mechanism of CP. Previous studies suggested that lesion of the spinothalamic tract is a necessary condition for development of CP. No previous study has in detail evaluated the association between the specific site of demyelinations and the presence of CP in MS. OBJECTIVE: The study aimed to evaluate the location of plaques in MS patients with CP including a group of MS patients without pain as a reference group. METHODS: All patients underwent a bedside sensory examination and MRI of the brain and spinal cord. MR imaging was acquired on an 1.5 Tesla MR equipment. A trained neuroradiologist, blinded to pain status, evaluated the MRI. RESULTS: Thirteen MS patients with CP and 10 MS patients without pain were included. Allodynia and/or dysesthesia were more frequent in pain patients (11/13 vs. 1/10, P<0.01). No difference was found in the number of patients with plaques in spinothalamic tract, dorsal column-medial lemniscus, dorsolateral funiculus, grey substance, thalamus or capsula interna. A non-significantly lower number of pain patients had lesions in thalamo-cortical pathways (8/13 vs. 10/10, P=0.027). CONCLUSIONS: No association between CP and site of demyelinations was found, although a trend toward a higher prevalence of intact thalamo-cortical pathways was seen in pain patients. CP was associated with allodynia, suggesting central hyperexcitability.

[Pre-collision pain and psychological distress predict poor outcome following acute whiplash trauma--secondary publication]. / Smertetilstand og psykologisk distress før uheldet praedikterer gener efter whiplash-traume--sekundaerpublikation.

Patients with acute whiplash trauma were followed to examine if pre-collision pain and psychological distress were associated with reduced work capability and neck pain at 12 month follow-up. Pre-collision unspecified pain was associated with reduced work capability, and neck pain and pre-collision psychological distress was associated with neck pain. In conclusion unspecified pain (as opposed to specified pain) and high accumulation of pre-collision psychological distress (as opposed to a single psychological disorder) before the collision was associated with poor recovery at follow-up.