2012 Annual Conference

Nelson, Chenae

US Army-Baylor University Doctoral Program in Physical Therapy; Fort Sam Houston, TX

A common belief regarding trigger point dry needling (TDN) is that eliciting a local twitch response (LTR) is an indicator of successful treatment, however there is sparse evidence to support this claim. Therefore, the primary purpose of this study was to determine if the presence of a LTR during needling was related to clinical improvement and/or improved lumbar multifidus (LM) muscle function in patients with low back pain (LBP). 

Sixty-six participants (39 males) were active duty service members and beneficiaries with LBP (age: 41.3 ± 9.2 years, body mass index: 28.8 ± 4.9 kg/m², months since initial LBP onset = 57.5 ± 83.3 months).

Participants underwent an initial standardized subjective and physical examination, including questionnaires, ultrasound imaging (USI) and pain pressure threshold (PPT) measurements of the LM muscle. USI was performed on the LM muscle at the L4-5 and L5-S1 spinal levels on the symptomatic side while at rest and during a sub-maximal contraction elicited by a contralateral arm lift maneuver. Pain algometry was performed to the LM muscle on the symptomatic side at the L3, L4, and L5 spinal levels.  Therapists palpated bilateral LM muscles, assessing for the presence of trigger points.  Treatment consisted of TDN to the LM muscles bilaterally at L3/L4, L4/L5, and L5/S1. During each needle insertion, therapists recorded whether or not a LTR was felt by the therapist and/or the patient. PPT, USI, and Numeric Pain Rating Scale (NPRS) measurements were collected immediately following TDN. All outcome measures including the Oswestry Disability Index (ODI) were additionally reassessed at a 1-week follow-up. Percent change in LM thickness (contracted-rest/rest) at the most symptomatic level was calculated for each assessment. Planned comparisons were made between the changes in each outcome measure in participants that experienced an LTR vs. those that did not using independent t-tests.

(please see methods)

A LTR occurred on the most symptomatic side in 56 subjects (84.8%) and at the most symptomatic level in 37 subjects (56.1%). Participants who experienced a LTR at the most painful side and level demonstrated significantly greater improvements in pain (p = 0.03) and % LM thickness change (p = 0.001) than those that did not experience a LTR. There were no significant relationships between LTR and 1-week changes in any outcome. 

A LTR during TDN to the LM muscle appears to be an important indicator of immediate improvement in pain and muscle function in patients with LBP. A LTR, however, does not seem to be an important indicator for sustained (1-week) improvements in pain, disability, or muscle function. Future research should investigate the value of LTRs in other muscles and neuro-musculoskeletal conditions.

LTRs during TDN appears to predict immediate clinical improvements, but should not be relied upon as a reliable indicator of lasting changes in patients with LBP.