Participatory action imaging in increasing clinician confidence of trigger point dry needling or trigger point injection of muscles requiring use of intercostal blocking: A case report

INTRODUCTION

Intercostal blocking is a palpation and grip technique used for trunk muscles in a variety of therapeutic interventions including trigger point dry needling (TrPDN), trigger point injections (TrPI), and acupuncture. Described as securing the trigger point (TrP) between the index and middle fingers, wherein each finger is placed in the intercostal spaces adjacent to a rib upon which the TrP has been fixed,^[1] this intercostal blocking is done in an effort to “block” the needle from unintentionally advancing into the intercostal space. In contrast to the intercostal blocking technique, blindly needling muscles of the trunk have been documented to result in potentially deadly iatrogenic complications.^[2] This palpation and grip may be used when injecting or dry needling muscles such as the rhomboids, the serratus anterior, or (as was the focus of this case report) the inferior aspect of the latissimus dorsi. Although intercostal blocking is a well-established and accepted technique currently utilized and perpetuated in clinical training of doctors of physical therapy, doctors of chiropractic, and doctors of medicine, there is no known study that verifies effectiveness of this technique as protective of the intercostal space and pleura. Pneumothorax is a well-recognized (albeit rare) adverse event related to acupuncture or TrPDN over the thorax.^[3-5] Despite the favorable safety profile, and despite a lack of literature on the subject, some dry needling clinicians (such as the clinician subject focus of this case report) privately confess to other certified dry needling clinicians and dry needling instructors, a lack of confidence in being able to safely perform TrPDN or TrPI on patients appropriate for receiving it, theoretically resulting in procedural underutilization.

Participatory action research (PAR),^[6] a novel research tool that includes the subject as an active participant in the research process for the purposes of enhancing skill and confidence,^[7] was used to educate the clinician subject on the procedural risks of intercostal blocking. Combined with pre-existing skill validation and certification, as well as pre-existing knowledge of the literature regarding incidence of iatrogenic injury from TrPDN or TrPI using intercostal blocking,^[8,9] PAR in the form of visual observation of technique parameters (defined in this case report as “participatory action imaging” or PAI) proved a useful tool in enhancing clinician confidence.

CASE REPORT

A 6’ 2”, 185 lbs., 53-year-old male clinician subject certified in dry needling with both right posterior/inferior scapular, anterior shoulder, and medial forearm pain; and subjective self-report of “high-anxiety” (objectively confirmed as “high anxiety”^[10] by State Trait Anxiety Inventory for adults or STAI^[11] form Y-1 score = 56) regarding performance of the intercostal blocking technique, was examined by a 5’5”, 150 lbs., 47-year-old male doctor of physical therapy certified in both TrPDN and musculoskeletal ultrasound (MSKUS) to determine the degree of coverage of the intercostal space and rib during intercostal blocking. The STAI is a psychological inventory based on a 4-point Likert scale and consists of 40 questions on a self-report basis. The STAI measures two types of anxiety. Form Y-1 measures state anxiety (anxiety about an event), and form Y-2 measures trait anxiety measures, or anxiety level as a personal characteristic.^[11]

The clinician subject was placed in a left lateral decubitus (e.g. side lying on the left side, right side up, and exposed to the examiner) position and rib imaged with a Siemens Acuson S2000 Ultrasound system with an 18L6 16 Hz high definition linear probe with and without intercostal blocking. The linear width of rib 10 (defined as the superficial distance between the superior and inferior border) was measured at the mid-axillary line, with and without intercostal blocking (once with deep exhalation and once with deep inhalation). Rib 10 was selected for study secondary to the larger width of the rib relative to more superior ribs, as well as it being a common rib for intercostal blocking dry needling of the latissimus dorsi (the TrP referral pattern of which the clinician subject complained).^[12]

The width of the rib was measured as 15.0 mm [Figure 1]. During intercostal blocking with maximal exhalation, the pleural space and an additional 13% of each side of the rib’s superior and inferior borders were completely blocked by the fingers of the examiner, leaving 11.1 mm, or 74% of the rib exposed [Figure 2]. Finally, during intercostal blocking with maximal inhalation, the pleural space and an additional 3% of each side of the rib’s superior and inferior borders were still completely blocked by the fingers of the examiner, leaving 14.1 mm, or 94%, exposed [Figure 3]. On visual inspection and interpretation of the images with the examiner, the clinician subject reported a “significant” decrease in self-reported anxiety (objectively confirmed as “low to no anxiety” by STAI^[10] form Y-1 score = 20) in performing the intercostal blocking technique, and an increase in self-reported subjective confidence with the technique.

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Figure 1:

Healthy 53-year-old male with right posterior/inferior scapular, anterior shoulder, and medial forearm pain; and self-report of high anxiety/low confidence regarding performance of the intercostal blocking technique. Musculoskeletal ultrasound imaging in short axis of right rib 10 imaged at mid-axillary line shows a normal, well-defined rib 15.0 mm wide.

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Figure 2:

Healthy 53-year-old male with right posterior/inferior scapular, anterior shoulder, and medial forearm pain; and self-report of high anxiety/low confidence regarding performance of the intercostal blocking technique. Musculoskeletal ultrasound imaging in short axis of right rib 10 during intercostal blocking and patient exhalation reveals intercostal space completely protected by examiner’s fingers, in addition to 13% of either side of the rib (111 mm/150 mm = 74% of rib 10 exposed).

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Figure 3:

Healthy 53-year-old male with right posterior/inferior scapular, anterior shoulder, and medial forearm pain; and self-report of high anxiety/low confidence regarding performance of the intercostal blocking technique. Musculoskeletal ultrasound imaging in short axis of right rib 10 during intercostal blocking and patient inhalation reveals intercostal space completely protected by examiner’s fingers, in addition to 6% of either side of the rib (141 mm/150 mm = 94% of rib 10 exposed).

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DISCUSSION

This case report presents a previously undescribed means for future research and clinician education regarding risk assessment of TrPDN, TrPI, or acupuncture of muscles requiring intercostal blocking. Although not specific to TrPDN or TrPI, studies have shown that ultrasound imaging for procedural guidance enhances clinician skill and confidence.^[13,14] Studies describing clinician safety and skill with the procedural aspects of TrPDN or TrPI have examined patient positioning,^[15] accuracy of rib palpation,^[16] and adverse event incidence,^[3,17,18] but not intercostal blocking specifically. Recent study suggests that increased patient subject muscle mass is inversely proportional to examiner rib palpation accuracy, with the error rate rising as high as 26.7% with no correlation between examiner self-reported confidence and actual accuracy.^[16] More study is needed to investigate how variation in patient (e.g., clinician subject) anatomy (e.g., rib morphology), examiner anatomy (e.g., finger size), needle direction, and specific rib being used for intercostal blocking influences patient safety. It is our hope that future publications will use this PAI technique to further explore and compliment epidemiological studies concluding that needling of muscular TrPs, including into those muscles that require intercostal blocking, can be performed safely, with minimal risk^[3,8,9,15] and with an acceptable level of confidence among properly trained professionals.

CONCLUSION

PAI is a valuable tool in demonstrating low procedural risk to clinician subjects that perform TrPDN or TrPI in muscles that require the intercostal blocking technique. Future study is required to determine meaningful shifts in, and minimal standards of, clinician subject confidence for safe patient application of TrPDN or TPI on muscles requiring intercostal blocking.