Ultrasonography Detection of Local Twitch Response During Dry Needling
Condition: Healthy Participants
Study type: Interventional

Summary: 
      Background: One treatment of Muscle trigger points (MTrPs) is deep dry needling (DN) with the
      purpose of obtaining local twitch responses (LTRs), which are highly effective in releasing
      MTrPs. In DN procedures the mechanisms associated with LTRs and the LTR intensities required
      for optimal clinical results are poorly understood, especially in relation to range of motion
      after intervention. Therefore, evaluating the intensity of LTRs is relevant for implementing
      DN in different clinical settings, such as in patients with muscular or neurological
      dysfunctions. One way to assess muscle contractions and LTRs is through ultrasound video
      analysis.

      The aim of this report was to evaluate the reliability of semi-automatic LTR intensities
      tracking during dry needling by assessing ultrasound signals with an image processing method,
      in addition to evaluating the relationship between LTR intensities and muscle elasticity.

      Method: Young males without signs or symptoms of musculoskeletal pain were included. Primary
      outcome measure was the LTR intensities determined by percentage change of muscle thickness.
      The secondary outcome measures were the muscle elasticity of medial gastrocnemius and
      hamstring, previous and posterior DN in both lower limbs for each subject. Three LTRs,
      detected by a physical therapist and ultrasound assessment, were induced by inserting a
      filament needle into muscle latent trigger points in medial gastrocnemius. The intensities of
      LTRs were measured by assessing ultrasound images using an optical flow method and through
      comparisons with manual detection.
    

Detailed description: 
      The aim of this report was to evaluate the reliability of semi-automatically tracking local
      twitch responses (LTR) intensities during dry needling by assessing ultrasound signals with
      an optical flow method designed to estimate movement of ROIs, in addition to evaluating the
      relationship between LTR intensities and muscle elasticity.

      Experimental protocol and measurements For each subject, the ROM of the medial gastrocnemius
      (MG) and hamstring (HA) was determined in both lower limbs using weight bearing and the
      active knee extension test, respectively, using a universal goniometer. For the knee
      extension test, 180° were subtracted from the obtained range, and the values were presented
      as negative. Both tests present excellent intra- and inter-rater reliability.

      All participants were placed in a prone position with the ankle locked at 90º. Latent MTrPs
      were identified in both MG using according the presence of a palpable taut band and
      hypersensitive spot in the palpable taut band as diagnostic criteria. The ultrasound
      transducer was positioned over the MG muscle using a fixing device that was composed of a
      thermoplastic polymer, with enough space for the dry needling (DN) technique to be performed.

      The deep DN was administered by a physical therapist with three years of experience in the
      technique. The ultrasound video (SonoSite Titan; Sonosite, Bothell, WA, USA) was recorded at
      60 frames per second captured through an external capture device from Epiphan Systems Inc.
      (Ottawa, Ontario, Canada). According to the perception of the physical therapist and the
      ultrasound assessment, the filament needle was inserted into the MTrP to achieve three LTRs.
      Posterior to DN application, the ROMs of the MG and HA were measured.

      The recorded ultrasound video was examined by the Camtasia software (Tech-Smith Corp, Okemos,
      MI, USA) to select three LTRs for latter analysis. Each LTR was tracked by the Lucas-Kanade
      optical flow (LKOF) algorithm with affine optic flow extension [12]. All analyses were
      performed using the Matlab® 2014 software (Mathworks Inc., Natick, MA, USA). For tracking
      muscle thickness, two ROIs (size 250 x 70 pixels) positioned on the superficial and deep
      aponeurosis were manually selected.

      Muscle thickness was normalized as a percentage of recruitment using the following equation:
      (thickness contracted-thickness rest/thickness rest)*100. For manual tracking of LTRs, the
      recorded ultrasound video was analyzed in the Matlab® 2014 software. Peak muscle thickness
      was determined by selecting muscle borders using hyperechoic aponeurosis lines.
    

Intervention name(s): detection of local twitch response intensities during dry needling
Intervention type(s): Procedure
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science