Stimulated by Li et al 2024.[1]
EA – electroacupuncture
CBZ – carbamazepine
TN – trigeminal neuralgia
IF – impact factor
G – google
tid – ter in die (latin for three times a day)– key to acronyms
I chose this paper in the Journal of Neurology (IF 6.0) because the 2×2 factorial design is uncommon in acupuncture research from China, it is moderately large, I like EA, and TN is a challenging condition to treat… plus this is probably one of the best sham controlled trials of acupuncture in TN to date.
The research team mainly come from Hangzhou, but they teamed up with colleagues from Jiaxing to make this a 2-centre study. Jiaxing is roughly halfway on a direct line northeast from Hangzhou to Shanghai, which are 176km apart by car. It is slightly further if you walk according to G maps.
A 2×2 factorial design uses 2 interventions and 2 shams or placebos in a parallel 4 arm prospective trial such that one arm has 2 active treatments, and one has two sham or dummy treatments, hence the term double dummy, which some readers may have hear in the past. The double dummy methodology has come up on this blog several times in the past, but perhaps the most dramatic was the huge trial on ovulation induction in PCOS from 2017: Segmental EA falls short in ovulation induction.[2]
120 patients with primary TN symptoms were randomised to the 4 arms and either received 60 minutes of EA 3 times a week for 4 weeks or sham EA with the same frequency, and either 300mg of CBZ daily (100mg tid) or placebo CBZ. They deliberately chose a low dose of CBZ for the treatment phase, but a higher dose was allowed as rescue medication after 4 weeks.
EA was applied across 2 points on the face and 2 points in the upper limb (LI4 to TE5). I assume the EA was applied to the affected side, but I cannot find this stated clearly. One of the points on the face was chosen to match the location of pain according to the branches of the trigeminal nerve: GB1 for the ophthalmic division; SI18 for the maxillary division; and ST6 for the mandibular division. ST7 was used in all cases. The needles used were 0.18x25mm on the face and 0.25x40mm on the upper limb.
EA was applied at 2Hz and 100Hz alternating and an intensity of 0.5mA to 1.0mA. The device used was a HANS-200A stimulator, which has a pulse width of 0.6ms at 2Hz and 0.2ms at 100Hz. For comparison, the devices I use in clinic have a pulse width of 0.12ms to 0.21ms, although this can be adjusted. As is standard for Han stimulation (named after Professor Jisheng Han), the frequency changes every 3 seconds.[3]
The sham EA involved superficial off-point needling and no electrical current. The sham points were typically 1cm away at the same vertical level with respect to the standard anatomical position.
The primary outcome was mean VAS pain over the previous 2 weeks from the patients’ daily pain rating. Outcomes were measured at baseline (after a 2-week monitoring phase), after 2 weeks treatment, after 4 weeks treatment, and then at week 16 and week 28. A variety of secondary outcomes were used in addition.
At week 4, the patients were asked to guess their treatment group allocation. Presumably they were presented with the 4 options, since the results attribute figures and percentages to these groups alone.
Both EA and CBZ were significantly better than their respective shams, and EA seemed slightly ahead of the low dose CBZ. Interestingly, there was some interaction between EA and CBZ. To give you an idea of the size of the effect, the mean VAS started at around 6 (out of 10) and dropped to under 2 in the combined group at 4 weeks. This level was maintained at 16 and 28 weeks.
References
1 Li R, Sun J, Luo K, et al. Electroacupuncture and carbamazepine for patients with trigeminal neuralgia: a randomized, controlled, 2 × 2 factorial trial. J Neurol. Published Online First: 31 May 2024. doi: 10.1007/s00415-024-12433-x
2 Wu X-K, Stener-Victorin E, Kuang H-Y, et al. Effect of Acupuncture and Clomiphene in Chinese Women With Polycystic Ovary Syndrome: A Randomized Clinical Trial. JAMA. 2017;317:2502–14.
3 Han J-S. Acupuncture and endorphins. Neurosci Lett. 2004;361:258–61.
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