Stimulated by Tang et al 2024.[1]
AACP – Acupuncture Association of Chartered Physiotherapists
key to acronyms
BAcC – British Acupuncture Council
3D – three dimensional
SP – spinous process (of a vertebra)
In 2001 we (the BMAS) ran a multidisciplinary conference titled Safety in Acupuncture. It was the first time the 3 big acupuncture organisations in the UK officially came together at an event (AACP, BAcC, and BMAS). It was at this event that I first met Elmar Peuker – a physician from Germany with interests in acupuncture and anatomy, and probably most famous in acupuncture circles as an author on the highly popular Color Atlas of Acupuncture.[2]
I remember asking him how far it was from GB20 to the vertebral artery. He said he did not know exactly, but subsequently he went to his university anatomy lab and made cross-sections of 10 cadavers along the trajectory of the needle at GB20. He got back to me with the result ~5cm (4–6cm depending on the size of the head) and we proceeded to plan a series of articles on ‘Anatomy for Acupuncture’ as well as a course on the subject.[3–5]
He went on to produce a larger atlas with coloured dissections superimposed on images of live human models, but this was about the same time as the digital 3D anatomy revolution began, so it did not seem to get a foothold in the market place and was never translated from German.[6]
Anyway, ever since that first experience of measuring depths relevant to the practice of acupuncture in real humans, I have taken an interest in similar papers.
This one comes from a group in Weifang – a city in the Shandong province of China about 100km due south of the Yellow River Estuary. They made careful measurements of the dry skulls and cervical vertebrae of 29 cadavers and the lateral cervical radiographs of 31 patients. 5 of the 203 cervical vertebrae were damaged during measurement and excluded from the study.
The reason for the study was to consider the safety of needling points in the posterior midline of the neck ie GV14, GV15, and GV16. All these points have been associated with damage to the spinal cord or medulla oblongata or bleeding in the vicinity of these structures.
The first thing they did was to connect the posterior border of the base of the mastoid process on each side of the skulls with a surgical suture. They then measured the shortest distance from this suture to the posterior border of the foramen magnum. This distance varied from 0.80mm to 6.90mm with the average being 4.65mm. There were no negative values, so this allows us to estimate the depth of the foramen magnum from the palpable posterior border of the base of the mastoid process.
Using the lateral cervical radiographs, they were able to define the safe depth of needling between C2 and the occiput. This was defined by a straight line drawn between the posterior border of the base of the mastoid process and the tip of the spinous process (SP) of C2. A needle placed to this depth at GV15 would still be clear of the vertebral canal by the distance from the tip of C2 to the vertebral canal on the inferior aspect of the SP. This latter distance was always greater than 10mm.
So, this paper has some useful guides and measures even though we (the BMAS) do not recommend the use of the points GV15 or GV16. The BMAS policy is to recommend needling up to the base of the skull for points above the SP of C2. Most often this would be GB20, although I do occasionally needle in the midline to the attachment of the nuchal ligament and walk the needle tip gradually deeper along the base of the skull to try to reproduce a patient’s pain. This is for presentations of midline pain in the head and the possibility of referral from the neck. Now I have a way of estimating how far I can safely go using this technique.
The authors of this paper do not discuss the lack of x ray vision in most acupuncturists, so we must keep in mind both the length of our needles and a healthy safety margin when needling deep in the posterior cervical region above C2.
GV14 is a point we teach and use a lot. Indeed, it is one of the first points we teach on the BMAS Foundation Course. Clinicians are often concerned about needling this point and err so much on the side of caution that they often do not even reach the supraspinous ligament. From this paper we get some useful measurements of the safety margin at GV14 by considering the distance from the tip of the SP of C7 to the posterior border of the spinal canal. The lower limit of the range of dry bone measurements was 17.34mm and the upper limit was 52.15mm. The same limits measured from lateral cervical radiographs was 23.88mm and 44.13mm respectively. The average in both samples was over 30mm, which is the figure I have always used to reassure novice needlers that they are not going to reach the spinal cord with a 30mm needle at GV14. Please note that the depth from the skin surface to the supraspinous ligament is at least 10mm and may be well over 30mm. The safety margin is from the point when you have already reached the surface of the ligament.
References
1 Tang Z, Liu J, Li J, et al. Use of bone landmarks for assessing the safety of acupuncture on the posterior midline of the neck region. BMC Complement Med Ther. 2024;24:168.
2 Hecker H-U, Steveling A, Peuker E, et al. Color Atlas of Acupuncture. Stuttgart: Thieme 2001.
3 Peuker E, Cummings M. Anatomy for the acupuncturist–facts & fiction. 1: The head and neck region. Acupunct Med. 2003;21:2–8.
4 Peuker E, Cummings M. Anatomy for the acupuncturist–facts & fiction. 2: The chest, abdomen, and back. Acupunct Med. 2003;21:72–9.
5 Peuker E, Cummings M. Anatomy for the acupuncturist–facts & fiction. 3: Upper & lower extremity. Acupunct Med. 2003;21:122–32.
6 Peuker ET, Filler TJ, Hecker H-U, et al. Anatomie Atlas Akupunktur: Dreidimensionale Akupunkturpunkt-Lokalisation. 1. Aufl. Stuttgart: Hippokrates-Verl 2005.
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