Medical Acupuncture
A Journal For Physicians By Physicians

Volume 13 / Number 2
"Aurum Nostrum Non Est Aurum Vulgi"

Auricular Acupuncture Stimulation Measured
On Functional Magnetic Resonance Imaging
David Alimi, MD
Alfred Geissmann, MD
Denis Gardeur, MD

ABSTRACT
Background Acupuncture studies have used neuroradiology procedures to examine the role of the central nervous system (CNS) in body acupuncture, but none of these previous studies investigated CNS relationships to auricular acupuncture.
Objective To examine the hypothesis that there are specific neurophysiological connections between ear acupoints and the CNS as evidenced by functional magnetic resonance imaging (fMRI) techniques.
Design, Setting, and Patients Prospective study of fMRI images in 10 healthy subjects at the Institute of Radiology in Basel, Switzerland, from March to May 2000.
Intervention Images were recorded in real time on cross-sections through the Rolandic area. The 5 stimulation conditions were conducted in a semi-randomized order: (1) at rest; (2) in the course of tactile stimulation of the right thumb; (3) in the course of tactile stimulation of the right thumb’s acupunctural site on the right ear; (4) after the insertion of this same site with 3 gold needles; and (5) in the course of the acupuncture mechanical stimulation of these same needles on the same site.
Results For 9 of 10 subjects, acupuncture stimulation of the needles pricked in the thumb auricular site produced a significant MRI signal, located on the somatotopic projection of the thumb, at the level of the S1 somesthesic area. This signal could be superimposed on that obtained by tactile stimulation of the thumb. For all 10 subjects, no signal at all was recorded in the course of the tactile stimulations of the auricular thumb site, nor in the course of the mere pricks of this same site.
Conclusions In this study, the power of fMRI as a tool of research supports the existence of specific neurophysiological connections between ear acupoints and human CNS. These results warrant further research in an attempt to understand the therapeutic operating mode of auricular acupuncture.

KEY WORDS
Functional MRI, Auricular Acupuncture, Neurophysiological Correlations, Central Nervous System, Auricular Acupuncture

INTRODUCTION
Either somatic or auricular acupuncture is now part of the contemporary therapeutic arsenal. Many teams have carried out research to study acupuncture’s clinical effectiveness, especially for pain alleviation. Most have been considered conclusive although some methods have
been criticized.1
Evidence-based medicine as practiced in the West has finally integrated acupuncture, acknowledging its efficacy in the treatment of pain, anxiety, and many other pathologies.2

Yet, few scientific studies have been dedicated to this subject. We know of only a few studies3-6 using recent neuroradiology, particularly functional magnetic resonance imaging (fMRI), that have been published to examine the effectiveness of somatopuncture.

After the initial empirical period and the classic description of the auricular acupuncture mapping by Paul Nogier in 1954 and published in 1969,7 central nervous system (CNS) mediation has always been evoked to explain the therapeutic action of this branch of medicine.8-12 Our purpose was to assess the relationship between somatotopic areas of the brain and the corresponding representation of the body on the external ear.

METHODS
Subjects
A total of 10 right-handed, healthy volunteers, 5 men and 5 women, aged 18-52 years, took part in this research. Written informed consent was obtained following a description of the conditions and the purpose of the study.
Materials
The recordings were made from March to May 2000 at the Institute of Radiology in Basel, Switzerland, on a 1.5-T MRI machine (General Electric Medical System [GEMS], equipped for EPI [echo planar imaging]). This instrument was equipped with accurate time and space resolutions (about 1 mm and 1/10 of a second). The fMRI objective was the increase of local blood pressure (BOLD effect: blood oxygen level dependent), which reflects brain activation without any radioisotope injection. Solid gold, non-magnetic reactive needles (0.4 mm in diameter, 30 mm in length) were especially made for this study, which was conducted in a confined magnetic chamber. We designed a simple, non-ferromagnetic mechanic system for the short-distance stimulation of the needles stitched in the ear.

Procedures
Five paradigm stimulations were made for every subject, whose order for testings was semi-randomized. We recorded the fMRI brain signals in Echo Planar Imaging (EPI) sequences:

Figure 1. Left: Subject 5, sequence 2. Record of functional MRI brain signal in the course of tactile stimulation of the right thumb. Right: Subject 5, sequence 2. Corresponding functional MRI power signal: intensity of signal according to time (1 unit = 3 seconds). Both: Cross-sections of Rolando area.

Every sequence lasted 5 minutes, with alternated periods of stimulation and rest, each lasting 30 seconds. To avoid any interference between the different signals, a 10-minute rest period occurred between every sequence. The sequence of acupuncture stimulation of the thumb’s auricular site was made at the end to make it distinct from the sequence of the thumb’s tactile stimulation.

Our decision to work on the thumb was determined by the neuroanatomical preponderance of its brain topical projection over the S1 somesthesic zone. We searched for the representation of the right thumb on the ear after electrodetection of its auriculodermal potential. A dynamometric clamp was calibrated at 2 kg/cm2 to induce a noticeptive stimulation of the thumb. The thumb’s electrodermal skin potential was determined by testing its probable sites of representation. The recording was made with an electronic microvoltmeter, using the differential measurement of the potential difference with 2 isolated coaxial electrodes that were loaded on springs respectively calibrated at a pressure of 15 and 80 g, after sending a 9-V detection current, on a sensitivity scale of 10 levels (Pointo Select DT+, Schwa Medico).

Figure 2. Left: Subject 5, sequence 5. Record of functional MRI brain signal in the course of mechanical stimulation of the gold needles stitched in the right thumb’s auricular site. Right: Subject 5, sequence 5. Corresponding functional MRI power signal: intensity of signal according to time (1 unit = 3 seconds). Both: Cross-sections of Rolando area

The MRI signals were recorded on EPI-sequenced cross-section (Figures 1 and 2). A 3-D, T1-weighted “anatomic” series was conducted. Spoiled gradient-recalled echo (SPGR) acquisition was also practiced. From that 3-D series and according to the anatomic atlas of Talairach and Tournoux,13 a reposition of the functional activation zones was made for every subject for the coherence of the results and for better correlation. The functional analysis was carried out with GEMS software.

RESULTS
Concerning the measurements of the auriculodermal potentials for a correct sensitivity, we only validated the measures which had a variation of more than 3 SDs from the basic value of the auricular potential for every subject. The values ranged from 0.84 to 1.16 V (Table 1 and Figure 3). For all 10 cases, the auricular representation of the right thumb was located on the right auricle, on the site that corresponds to that on the cartography concepts developed by Nogier and by Kovacs (Figure 4). For every subject, the tactile stimulation of the right thumb produced a signal recorded on the left rising parietal auricle with a small piping on the supramarginalis gyrus, and sometimes at the level of the associative zones. A faint display of the oval center was observed for almost every subject except 2 (subjects 9 and 10). For 3 subjects, a bilateral recording was obtained (subjects 2, 7, and 8), coinciding with the stimulation of the interhemispheric pathways. Some frontal artifacts were recorded, and several of them were linked with the presence of dental metals. Other artifacts were linked with the hypersensitivity of the bone recording on the skull base, linked with the EPI technique.

For all 10 subjects, no signal could be recorded during the tactile stimulation of the thumb’s ear site nor during the simple stitches in this same site. Conversely, for 9 subjects, acupunctural stimulation of the needles stitched in the thumb’s auricular site produced a significant signal, located on the somatotopical projection of the thumb, at the level of the S1 somesthesical zone. This signal was superimposable to that obtained by the thumb’s tactile stimulation (Figures 5-8).
Acupuncture stimulation of the thumb’s auricular representation produced a more powerful and more coherent fMRI signal in 3 cases (subjects 1, 2, and 4). These signals were also present in the association zones (supramarginalis gyrus) [subjects 3 and 8]. In some cases, contralateral signals were recorded (subjects 3, 7, and 8).

Figure 4

DISCUSSION
As a result of the absence of any thumb pathologies among the subjects, no brain representation was found in the rest period for fMRI signals. Mechanical stimulation of the ear thumb zone did not produce any activity, neither in the thumb’s somesthesic zone nor in that of the ear itself (situs of the face), the stimulation having concerned only a small area of about 2 mm.2 The simple stitching of the thumb’s auricular site did not produce any signal. This finding is congruent with basic neurophysiology, since the stitch is not painful and no thumb pathology existed. On the other hand, with no stimulation of any nature (e.g., mechanical [acupunctural], electrical, magnetic, laser), no link could be activated.

From the ear, the only positive recordings concerned the magnetic spots generated by the acupunctural stimulation of the thumb’s ear sites. These hypersignals show the local increase of the blood pressure with a relative hyperoxygenation of the functional zone (BOLD effect). These hypersignals were displayed for every subject except 1 (for whom the signals were lost, the subject being overcome by panic in the magnetic chamber in the course of the recording phase). For 3 subjects, some bilateral recordings were obtained. This corresponds to the data of the auriculoacupuncture clinic, since a bilateral display is found for about 20%-30% of cases. Two of these 3 cases also corresponded to a bilateral recording in the course of the tactile stimulation of the thumb. This shows good concordance between the neuroanatomical pathways and the reflex of the ear.

These signals were superimposable on those obtained by the thumb tactile stimulation, evidencing the periphery-ear-brain somatotopical connection, in the S1 somesthesic zone configuration. The somatotopical projection in the brain obeys the law of Khaler: the fibers penetrate into the cord in the caudorostral direction, according to the metametric segmentation, which determines somatotopic moving up along the main neural centers, in the homunculus of Rolando configuration, either vertical, head down (spinal cord, reticular formation, cerebellum, S1 somesthesic and motory zones); horizontal (thalamus); or oblique, head forward (S2 somesthesic zone).14-16

Figure 3

Our findings indicate that the pain generated at the thumb level (with the dynamometric clamp), spread on a somatotopic configuration moving up along the ascending neural pathways. It then displayed itself on the ear, at the level of the site corresponding to the thumb’s site on the auricular somatotopy. That configuration is brought to the ear by the nerves that innervate the auricle (V, VII, IX, X, SCP), for which somatotopy can be found. From this auricular display, the pain messages take the reticulothalamic tracts and then the thalamocortical ones.

CONCLUSION
No research proved the existence of a neurophysiological connection between ear pavilion and brain until now. The results of this study are significant and specific. In further research, we propose to study the brain-ear reciprocal relation in some pathological cases, and explain from these cases the therapeutic operating mode of auricular acupuncture.

Funding/Support
This study was possible due to research funds from the GLEM (Groupe Lyonnais d’Etudes Médicales, Lyon, France); by the SEDATELEC (Electronique Médicale, Irigny, France); and by the EIPN (Ecole Internationale Paul Nogier, Lyon, France).

ACKNOWLEDGEMENT
Dr David Alimi dedicates this study to the memory of René Kovacs, who showed him the way of that dis-
cipline and gave him a desire for scientific research in neurophysiology. The authors thank Dr Richard C. Niemtzow and Dr Terry Oleson for translating the orginal French manuscript into English.

Figure 5
Patient 1: tactile stimulation of right thumb.	Patient 1: acupuncture stimulation of right thumb’s ear site.
Patient 2: tactile stimulation of right thumb.	Patient 2: acupuncture stimulation of right thumb’s ear site.
Patient 3: tactile stimulation of right thumb.	Patient 3: acupuncture stimulation of right thumb’s ear site.

Figure 6
Patient 4: tactile stimulation of right thumb.	Patient 4: acupuncture stimulation of right thumb’s ear site.
Patient 5: tactile stimulation of right thumb.	Patient 5: acupuncture stimulation of right thumb’s ear site.
Patient 6: tactile stimulation of right thumb.	Patient 6: acupuncture stimulation of right thumb’s ear site.

Figure 7
Patient 7: tactile stimulation of right thumb.	Patient 7: acupuncture stimulation of right thumb’s ear site.
Patient 8: tactile stimulation of right thumb.	Patient 8: acupuncture stimulation of right thumb’s ear site.
Patient 9: tactile stimulation of right thumb.	Patient 9: acupuncture stimulation of right thumb’s ear site.

Figure 8

Patient 10: tactile stimulation of right thumb.

Patient 10: acupuncture stimulation of right thumb’s ear site.

NOTE: Circled areas in figures 5 through 8 indicate areas stimulated.

REFERENCES

AUTHORS’ INFORMATION
Dr David Alimi is a Neurophysiologist and Associate Professor of Auriculoacupuncture at the Faculty of Medicine in Paris, France.

David Alimi, MD
8, rue de Budapest
94140 Alfortville, France
E-mail: alimi@club-internet.fr

Dr Alfred Geissman is a Radiologist and Director, Radiology Institute in Basel, Switzerland.

Alfred Geissman, MD
Rumelinbachweg 6
CH-4054 Basel, Switzerland

Dr Denis Gardeur is a Neuroradiologist and former Neuroradiology Chief Assistant at the Pitie-Salpetriere Hospital in Paris, France.

Denis Gardeur, MD
Scanner Alesia
119, Avenue du General Leclerc
75014 Paris, France

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