Efficacy of two cannabis‐based medicinal extracts for relief of central neuropathic pain from brachial plexus avulsion: results of a randomised controlled trial
Bibliographic record
Abstract
Avulsion of nerve rootlets from the spinal cord following traction injuries to the brachial plexus frequently produces a highly characteristic pain syndrome. Constant spontaneous crushing and burning pain is felt in the distal part of the anaesthetic limb, frequently accompanied by shooting pain. It is not uncommon for the pain to persist for many years. The consistency of description between subjects coupled with the anatomical precision of the diagnosis provides a remarkable human model of central neuropathic pain. Opioids, anticonvulsants and tricyclic antidepressants are all used in the empirical management of this condition. They are partially effective at best and there is only anecdotal evidence to support their use. Many of our patients have given us spontaneous reports of the efficacy of ‘street’ cannabis. This has led us to test two cannabis-based whole plant medicinal extracts administered via oromucosal spray to patients with this condition. Forty-eight patients were enrolled. They all had at least one brachial plexus root avulsion for at least 18 months. They also had pain of at least 4 out of an 11-point box scale at the time of enrolment. The study was a randomised double-blind crossover trial consisting of three 2-week periods following a run-in period of 7–24 days. Patients continued on all previous stable medications including analgesics. During each 2-week period, subjects received in random order either placebo, delta-9-tetrahydrocannabinol (THC) 25 mg.ml or delta-9-tetrahydrocannabinol 25 mg.ml with cannabidiol (THC:CBD) 25 mg.ml, given as patient-activated oromucosal 100-μl sprays. Eleven-point box scales for pain and sleep, short form McGill, visual analogue scale, general health questionnaire-12, sleep disturbance and pain disability index were all recorded. Table 1 shows a summary of the results at week two of each of the study periods. Both the THC and THC:CBD extracts decreased pain and improved sleep. The effects were moderate although mostly statistically significant. Patients had not maximally titrated their doses at the end of the 2-week study periods. In addition, they remained on their pre-existing analgesic therapy throughout the study. A longer study period and use of cannabis-based medicinal extracts as the sole analgesic may well show a bigger analgesic effect. However, given the refractory nature of the pain in this patient group, this study shows that cannabis-based medicinal extracts represent a significant advance in treatment.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.005 | 0.002 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.009 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".