Acupuncture stimulation elicits a sensory response termed deqi which literally means "the arrival of vital energy" in traditional Chinese medicine ( TCM). Multiple unique sensations experienced by the patient around the site of needle manipulation are often described as suan (aching or soreness), ma (numbness or tingling), zhang (fullness/distention or pressure) and zhong (heaviness) . While pain is also experienced occasionally, the type of pain has not been well characterized. The increased resistance of the needle is felt by the acupuncturist (needle grasping) as tense, tight and full like "a fish biting onto the bait." as described in the literature [1–3]. Needle grasping is believed to be related to clinical efficacy [1–4] although little data are available [5–7]. The acupuncturist's skills, competence and understanding of the TCM theory also play an important role in the therapeutic outcome .
Randomized, placebo-controlled clinical trials of acupuncture evaluate its efficacy by separating the specific effects from the non-specific ones . While a number of clinical trials failed to find verum acupuncture more effective than sham acupuncture in migraine [9, 10] low back pain [11, 12] and knee osteoarthritis [13, 14], both verum and sham acupuncture were more beneficial than the waiting control. However, many of the studies included in the analysis did not satisfy the criteria for dosage adequacy required for optimal clinical efficacy  and that sham is not necessarily inert [16, 17]. The intensity of the psychophysical and neurological response of deqi is now proposed to serve as a basis for dosage measurement [15, 18], calling for a better understanding of the qualitative and quantitative characterization of the deqi sensation.
Most studies described the qualitative characteristics of sensations unique to acupuncture based on interviews of patients and expert acupuncturists [5, 19]. Recently, several groups created quantitative sensation scales and deqi indices based on pain questionnaires distributed to acupuncture patients [5, 20–25]. Classical sensations such as aching, soreness, numbness, fullness and heaviness were included. Sharp pain is not regarded as a beneficial deqi sensation by most acupuncturists. Most reports failed to separate it from dull pain in the categorization of deqi response; only a few reports with quantitative measures distinguished sharp pain from deqi[15, 20, 22]. We attempted to separate the acupuncture sensations into two major categories, namely sensations that do not hurt (aching, soreness and dull pain) as deqi and sensations that do hurt (sharp pain) as noxious stimulation [26, 27]. Our findings showed that the deqi response was elicited in 71% acupuncture versus 24% tactile and that the frequency and intensity of sensations were significantly greater than tactile. Dull pain was significantly different from the tactile group among the gamut of sensations comprising deqi. Importantly, we have consistently observed distinct patterns of limbic network hemodynamic response in the brain, namely deactivation in deqi and activation in sharp pain. Our findings are in fair agreement with Macpherson's report  and the Southampton group . Taken together, these psychophysical and hemodynamic response patterns may provide a qualitative and quantitative measure of the patient's response to manual needle manipulation [26–28].
This pilot survey aims to provide a picture by focusing on the items that are seldom described such as the subject's throbbing and dull pain and the acupuncturist's grasping sensation, serving as a foundation for a better understanding of acupuncture effects.