Bilateral and multiple cavitation sounds during upper cervical thrust manipulation

Abstract

BackgroundThe popping produced during high-velocity, low-amplitude (HVLA) thrust manipulation is a common sound; however to our knowledge, no study has previously investigated the location of cavitation sounds during manipulation of the upper cervical spine. The primary purpose was to determine which side of the spine cavitates during C1-2 rotatory HVLA thrust manipulation. Secondary aims were to calculate the average number of pops, the duration of upper cervical thrust manipulation, and the duration of a single cavitation.MethodsNineteen asymptomatic participants received two upper cervical thrust manipulations targeting the right and left C1-2 articulation, respectively. Skin mounted microphones were secured bilaterally over the transverse process of C1, and sound wave signals were recorded. Identification of the side, duration, and number of popping sounds were determined by simultaneous analysis of spectrograms with audio feedback using custom software developed in Matlab.ResultsBilateral popping sounds were detected in 34 (91.9%) of 37 manipulations while unilateral popping sounds were detected in just 3 (8.1%) manipulations; that is, cavitation was significantly (P < 0.001) more likely to occur bilaterally than unilaterally. Of the 132 total cavitations, 72 occurred ipsilateral and 60 occurred contralateral to the targeted C1-2 articulation. In other words, cavitation was no more likely to occur on the ipsilateral than the contralateral side (P = 0.294). The mean number of pops per C1-2 rotatory HVLA thrust manipulation was 3.57 (95% CI: 3.19, 3.94) and the mean number of pops per subject following both right and left C1-2 thrust manipulations was 6.95 (95% CI: 6.11, 7.79). The mean duration of a single audible pop was 5.66 ms (95% CI: 5.36, 5.96) and the mean duration of a single manipulation was 96.95 ms (95% CI: 57.20, 136.71).ConclusionsCavitation was significantly more likely to occur bilaterally than unilaterally during upper cervical HVLA thrust manipulation. Most subjects produced 3–4 pops during a single rotatory HVLA thrust manipulation targeting the right or left C1-2 articulation; therefore, practitioners of spinal manipulative therapy should expect multiple popping sounds when performing upper cervical thrust manipulation to the atlanto-axial joint. Furthermore, the traditional manual therapy approach of targeting a single ipsilateral or contralateral facet joint in the upper cervical spine may not be realistic.

Unilateral and Multiple Cavitation Sounds During Lumbosacral Spinal Manipulation

“…We found the mean duration of a single pop to be 2.69 milliseconds during a lumbosacral HVLA thrust manipulation. This value is very similar to the 4-millisecond duration reported by Reggars and Pollard 28 for the "average length of joint crack sounds," the 5.66-millisecond duration for the mean duration of a single pop during upper cervical thrust manipulation, and 4.13 milliseconds during cervicothoracic junction thrust manipulation reported by Dunning et al 25,26 Although Herzog et al 3 reported triphasic "cavitation signals" with a mean duration of 20 milliseconds, it is unclear whether this value represents a single PS or multiple PSs. However, in our study, we calculated the time interval between the beginning of the ascent of the first energy burst and the end of the descent of the last energy burst of a PS event for the duration of a single pop.…”

“…The results of our study are difficult to compare directly with the previous studies 2, 17,25,28 on this topic. Similarly, Cramer et al 2 reported 93.5% of the PSs to have occurred on the upside facet articulations and with just 1.43 PSs per participant.…”

“…Skin-mounted accelerometers were secured bilaterally 25 mm lateral to the midline of the L5-S1 interspace (Fig 2) before the lumbosacral HVLA thrust manipulation delivery. The accelerometers were connected to a data acquisition system (Focusrite Scarlett 2i2 [Focusrite Audio Engineering Ltd, High Wycombe, United Kingdom], 96 KHz, 24-bit conversion) and a MacBook Pro (Apple, Cupertino, California) laptop with Audacity software for audio acquisition 25 with a sampling frequency set at 96 000 Hz. The Audacity software normalized automatically the audio energy to values ranging between -1 and +1 (no unit of measurement).…”

“…As described in our previous studies, 25,26 the duration of the thrusting procedure was considered the time interval between the beginning of first pop and the end of the last pop (Fig 6).…”

“…24 Moreover, in a previous study, Cramer observed a direct relation between the popping sound and the gapping phenomena but not how much the joint gapped. 25 Notably, Kawchuk et al 15 found a void within the joint that persists after the sound production that could explain the ZJ gapping after HVLA thrust manipulation observed by Cramer et al 24,25 More recently, another research group tried to analyze the PS phenomenon using sound wave signals processed by a time-frequency analysis. 8,26 The authors observed that the sound was composed of single and multiple energy releases (ie, single versus multi-peak sounds).…”