The latest lectures in my acupuncture course have covered the use of acupuncture (and, incidentally, massage and laser therapy) for “neuromodulation” of the twelve cranial nerves. “Neuromodulation” is a somewhat vague term often used to suggest some clinically relevant and likely beneficial effect on the function of the nervous system. More casually, this is described with terms like “give it a boost” or “help that nerve be a happier nerve.” This is a theme in this course, in which the fact that needling, electrical stimulation, and possibly laser stimulation have measurable effects on nerves is assumed to imply clinically meaningful and beneficial effects in patients. As I’ve said before, this is a plausible hypothesis, but it has to be proven with appropriate clinical research, which often turns out not to be the case.
Many of the cranial nerves are not directly accessible, and often they have functions that are not likely to be associated with clinical problems we deal with in veterinary patients. However, some nerves, especially CN V, VII, VIII and X do have functions associated with fairly common and important clinical problems, so modulation of these functions could potentially have clinical value.
Much is made in these lectures of the anatomic relationships between elements of the nervous system, with the implication that these anatomic connections imply relevant functional connections we can manipulate with acupuncture. However, it is important to realize that one can’t reliably infer functional relationships solely form anatomic relationships. Exercise, for example, stimulates gastrointestinal motility despite the lack of a simple and obvious anatomic relationship to predict this. On the other hand, the spinal cord is pretty widely and directly connected to nearly everything in the body, yet the evidence is strong that chiropractic manipulation of the spine has virtually no significant effects on the body apart from the spine itself. The obvious anatomic relationship turns out not to have a corresponding functional relationship.
The real question, of course, is whether there is actual clinical value to acupuncture etc. in patients with problems that we might reasonable suspect could be influenced by modulation of cranial nerves. That seems to be far from clear based on the evidence presented in these lectures.
As an example, the role of acupuncture in controlling seizures is mentioned several times. Direct and indirect stimulation of CN V and CN X are suggested as likely ways to influence seizures due to anatomic and functional relationships between these nerves and the parasympathetic nervous system, which does play a role in controlling seizure activity. And there is evidence that direct stimulation of CN X via an implanted electrical nerve stimulator. However, this is clearly not the same thing as acupuncture. So what does the clinical evidence suggest?
As usual, there is poor evidence in veterinary patients. A couple of uncontrolled studies in dogs have been done. One suggested improvement in seizure frequency, but such improvement has also been seen in epileptic dogs receiving placebo treatment, so uncontrolled studies can’t be taken as reliable evidence of an effect. The evidence is still limited and at high risk of bias in humans, but there is more research, and reviews do not suggest a strong or repeatable clinical benefit.
Cheuk DK, Wong V. Acupuncture for epilepsy. Cochrane Database Syst Rev. 2014 May 7;5:
We included 17 RCTs with 1538 participants that had a wide age range and were suffering mainly from generalized epilepsy. The duration of treatment varied from 7.5 weeks to 1 year. All included trials had a high risk of bias with short follow-up. treatment in the included trials.
Available RCTs are small, heterogeneous and have high risk of bias. The current evidence does not support acupuncture for treating epilepsy.
Yang C, Hao Z, Zhang LL, Guo Q. Efficacy and safety of acupuncture in children: an overview of systematic reviews. Pediatr Res. 2015 Aug;78(2):112-9.
We aim to update the evidence for the efficacy and safety of acupuncture for children and evaluate the methodological qualities of these studies to improve future research in this area. We included 24 systematic reviews, comprising 142 randomized controlled trials (RCTs) with 12,787 participants. Only 25% (6/24) reviews were considered to be high quality (10.00?±?0.63). High-quality systematic reviews and Cochrane systematic reviews tend to yield neutral or negative results (P = 0.052, 0.009 respectively). The efficacy of acupuncture for five diseases (Cerebral Palsy (CP), nocturnal enuresis, tic disorders, amblyopia, and pain reduction) is promising. It was unclear for hypoxic ischemic encephalopathy, attention deficit hyperactivity disorder, mumps, autism spectrum disorder (ASD), asthma, nausea/vomiting, and myopia. Acupuncture is not effective for epilepsy. Only six reviews reported adverse events (AEs) and no fatal side effects were reported. The efficacy of acupuncture for some diseases is promising and there have been no fatal side effects reported. Further high-quality studies are justified, with five diseases in particular as research priorities.
Another example was the condition of xerostomia or “dry mouth.” This can occur with radiation or surgical therapy around the mouth as well as for other reasons, It is hard to assess in veterinary patients and so not a regular target for therapy, but it is used as an example in these lectures of clinical benefits from neuromodulation through acupuncture, in this case of CN IX. However, the evidence in humans does not suggest that the theoretical benefits of acupuncture stimulation of CN IX translate into significant benefits for actual patients with xerostomia.
Jedel E. J Oral Rehabil 2005 Jun;32(6):392-6. Acupuncture in xerostomia–a systematic review.
The aim of this systematic review was to assess the efficacy of acupuncture in the management of xerostomia….Three articles met the criteria for inclusion and a criteria list was used to assess the quality of these studies. The studies were considered to be of high quality or low quality in accordance with the criteria list utilized. The results of the trials were considered positive, negative or indifferent based on statistically significant between group differences. The criteria list utilized indicate that one of the three studies was of high quality and it presents indifferent results. One of the two studies of low quality presents positive results and one presents indifferent results. An analysis of the results degree of evidence resulted in no evidence for the efficacy of acupuncture in the management of xerostomia. This systematic review shows that there is no evidence for the efficacy of acupuncture in the management of xerostomia. There is a need for future high quality randomized controlled trials.
Wu X, Chung VCh, Hui EP, et al. Effectiveness of acupuncture and related therapies for palliative care of cancer: overview of systematic reviews. Sci Rep. 2015 Nov 26;5:16776.
…There is evidence for the therapeutic effects of acupuncture for the management of cancer-related fatigue, chemotherapy-induced nausea and vomiting and leucopenia in patients with cancer. There is conflicting evidence regarding the treatment of cancer-related pain, hot flashes and hiccups, and improving patients’ quality of life. The available evidence is currently insufficient to support or refute the potential of acupuncture and related therapies in the management of xerostomia, dyspnea and lymphedema and in the improvement of psychological well-being. No serious adverse effects were reported in any study.
Hanchanale S, Adkinson L, Daniel S, et al. Systematic literature review: xerostomia in advanced cancer patients. Support Care Cancer. 2015 Mar;23(3):881-8.
Limited published data exists reporting the effectiveness of measures in the treatment of xerostomia in cancer patients. Based on primary research of low quality, firm conclusions cannot be drawn. However, pilocarpine, artificial saliva, chewing gum and acupuncture can be tried based on the available data. This highlights the explicit need to improve our evidence base. Properly constructed randomized controlled trials demonstrating effectiveness of pharmacological and non-pharmacological interventions for dry mouth are required.
Furness S, Bryan G, McMillan R, et al. Interventions for the management of dry mouth: non-pharmacological interventions. Cochrane Database Syst Rev. 2013 Sep 5;9:CD009603.
There were nine studies (total 366 participants randomised) included in this review of non-pharmacological interventions for dry mouth which were divided into three comparisons. Eight studies were assessed at high risk of bias in at least one domain and the remaining study was at unclear risk of bias….There is low quality evidence that acupuncture is no different from placebo acupuncture with regard to dry mouth symptoms, which is the most important outcome …There is insufficient evidence to determine the effects of electrostimulation devices on dry mouth symptoms. It is well known that dry mouth symptoms may be problematic even when saliva production is increased, yet only two of the trials that evaluated acupuncture reported dry mouth symptoms, a worrying reporting bias. There is some low quality evidence that acupuncture results in a small increase in saliva production in patients with dry mouth following radiotherapy….Reported adverse effects of acupuncture are mild and of short duration, and there were no reported adverse effects from electrostimulation.
Similar results are found when the other main examples of purported neuromodulation of cranial nerves through acupuncture are investigated. What this says to be is that despite plausible anatomic relationships that suggest acupuncture could be useful in altering the function of these nerves to the benefit of patients, it seems to be very difficult to prove in the real world. This might mean we need more and better research, as the reviews usually conclude. Or it might mean that there is no effect to find. Certainly, therapies with a strong and definitive benefit aren’t not usually difficult to validate in clinical research, so the difficulty in showing benefits for acupuncture is reason for some skepticism.