An Exploration of the Needling Depth in Acupuncture: The Safe Needling Depth and the Needling Depth of Clinical Efficacy

Table 6

Summary of researches involving the correlation between therapeutic effect and needling depth.

Authors and year	Subjects and sample size	Investigated acupuncture points and their body regions/meridians	Parameters used in comparison and related factors	Results, suggestions, and conclusions
He et al. 2012 [98]	63 subjects with trigeminal neuralgia (32 in deep and 31 in shallow puncturing group)	ST7, LI4, LV3, BL2, ST2, and Jiacheng Jiang	Pain index (VAS), traditional Chinese medicine symptoms index, and clinical therapeutic effect	(1) The total effective rate was 93.8% in deep puncturing group, superior to that of 87.1% in shallow puncturing group; (2) No adverse reaction was observed in both groups; (3) Deep puncturing at ST7 to the depth of sphenopalatine ganglion was more effective than routine puncturing
Park et al. 2011 [99]	5 participants	LI13, LU4 and 2 control points	Needling depth, needle rotation, and oscillation	(1) Pilot study using ultrasound tried to explore the correlation between de-qi sensation and needling depth/needle manipulation; (2) Shallower insertion induced more sharp sensations; (3) Deeper insertion induced more dull sensations; (4) Needle rotation significantly increased the dull sensations
Skjeie et al. 2011; [100]	7 randomized patients (3 in placebo group and 4 in acupuncture treatment group)	ST36	Bilateral insertion at ST36 at the depth of 12 mm, reduction of crying time from baseline	(1) A pilot, open, randomized, and single-blinded controlled trial to assess the feasibility of acupuncture treatment for infantile colic; (2) No adverse events were reported; (3) Acupuncture group had more reduction of crying time from baseline
Lu and Tang 2011 [101]	21 cases of irritable bowel syndrome of diarrhea	IR13, CV12, ST25, CV4, LR14, LI11, LI4, SP9, ST36, and LR3	The scale for the severity degree of symptom (IBS-SSS)	(1) Various needling depths ranged 2–12 mm as documented in Lingshu (Miraculous Pivot); (2) After treatment, there was significant change in IBS-SSS, and the effective rate may reach 90.5%; (3) The longer the session of treatment was, the better the efficacy was obtained; (4) Confirmed the needling depth recorded in Lingshu
Itoh et al. 2011 [102]	22 healthy volunteers	Tender point in the extensor digital muscle, in the skin, and in the nonsegmental limb (anterior tibial muscle)	Pressure pain threshold, electrical pain threshold, and needling depth (3 mm to 10 mm)	(1) Randomized controlled trial; (2) Immediate pain relief in muscle group (depth of 10 mm insertion into extensor digital muscle) which was better than skin group (depth of 3 mm); (3) Acupuncture stimulation of muscle increases the PPT and EPT of fascia. The depth of needle penetration was important for the relief of muscle pain
Chen et al. 2009 [32]	204 pediatric patients aged 7–15	12 abdominal acupuncture points CV-3, CV-4, CV-6, CV-10, CV-12, CV-14, KI-12, ST-24, ST-25, SP-15 LV-13, and LV-4	Gender, age, BW, and waist girth	(1) Using the therapeutic depth over safety depth ratio (T/S ratio) as the indicator of therapeutic depth; (2) No significant difference in the T/S ratio between genders; (3) The T/S ratio of these 12 acupuncture points ranged from 0.67 to 0.88 and increased significantly with body weight,; age, and waist girth; (4) The therapeutic depth of abdominal acupoints was closer to the safe depth in overweight and older children aged 7 to 15; (5) No significant difference between genders
Groenemeyer et al. 2009 [24]	58 patients with low back pain	BL25, BL26	BMI	(1) An association between de-qi and needle location existed; (2) The distance between BL25 and BL6 to the vertebral line is 3.49±0.58 and 3.32±0.53 cm, respectively; (3) There was a significant correlation between the interscapular distance and the thickness of the soft tissue layer with the BMI at both acupuncture points
Streitberger et al. 2007 [25]	50 patients receiving acupuncture including PC6 bilaterally (97 wrists)	PC6	Nerve penetrated or contacted; DQ	(1) Association between nerve contact and de-qi was discussed. De-qi was elicited in 85 cases. No association between the number of nerve contacts and de-qi was found; (2) The mean distance from the needle tip to the nerve was 1.8 mm (standard deviation 2.2; range 0–11.3). Nerve contacts were recorded in 52 cases, in 14 of which the nerve was penetrated by the needle
Lin 1997 [29]	80 cadavers (including 30 newborns) and 240 adults for safety depth; 300 real subjects for de-qi depth	All back bladder meridian points and chest points	Gender, Tong Shen Cun, BL, BW (normal, over and under-weight) DQ, and AW	(1) Depths were deeper as compared to ancient writings. The depths highly correlated with body thickness and Tong Shen Cun; (2) De-qi depth was related to therapeutic effect; (3) De-qi depths of chest points were greater in females but not in back points
Lin and Wang 1994 [30]	300 adults	Total of 75 acupoints in head, neck, trunk, and lower limb	Gender, BW, and DQ	(1) Discussed de-qi depth but not safe depth; (2) Depth of de-qi was greater in males and people with greater body weight; (3) Depths in neck region were more superficial in trunk and limbs
Lin 1991 [31]	107 adults	Acupoints in the chest and back of subjects receiving acupuncture therapy	Gender, BW (normal, over- and underweight), BL, and DQ	(1) Overweight group had the greatest de-qi depth; (2) Points of female chest had greater depth than male; (3) No correlations between the de-qi depth and electric resistance of each point