Diego Turo

Ultrasonic Characterization of the Upper Trapezius Muscle in Patients with Chronic Neck Pain

Myofascial trigger points (MTrPs) are palpable, tender nodules in taut bands of skeletal muscle that are painful on compression. MTrPs are characteristic findings in myofascial pain syndrome (MPS). The role of MTrPs in the pathophysiology of MPS is unknown. Localization, diagnosis, and clinical outcome measures of painful MTrPs can be improved by objectively characterizing and quantitatively measuring their properties. The goal of this study was to evaluate whether ultrasound imaging and elastography can differentiate symptomatic (active) MTrPs from normal muscle. Patients with chronic (>3 months) neck pain with spontaneously painful, palpable (i.e., active) MTrPs and healthy volunteers without spontaneous pain (having palpably normal muscle tissue) were recruited for this study. The upper trapezius muscles in all subjects were imaged, and the echotexture was analyzed using entropy filtering of B-mode images. Vibration elastography was performed by vibrating the muscle externally at 100 Hz. Color Doppler variance imaging was used to quantify the regions of color deficit exhibiting low vibration amplitude. The imaging measures were compared against the clinical findings of a standardized physical exam. We found that sites with active MTrPs (n = 14) have significantly lower entropy (p < 0.05) and significantly larger nonvibrating regions (p < 0.05) during vibration elastography compared with normal, uninvolved muscle (n = 15). A combination of both entropy analysis and vibration elastography yielded 69% sensitivity and 81% specificity in discriminating active MTrPs from normal muscle. These results suggest that active MTrPs have more homogeneous texture and heterogeneous stiffness when compared with normal, unaffected muscle. Our methods enabled us to improve the imaging contrast between suspected MTrPs and surrounding muscle. Our results indicate that in subjects with chronic neck pain and active MTrPs, the abnormalities are not confined to discrete isolated nodules but instead affect the milieu of the muscle surrounding palpable MTrPs. With further refinement, ultrasound imaging can be a promising objective method for characterizing soft tissue abnormalities associated with active MTrPs and elucidating the role of MTrPs in the pathophysiology of MPS.

A Systematic Comparison Between Subjects With No Pain and Pain Associated With Active Myofascial Trigger Points

To determine whether standard evaluations of pain distinguish subjects with no pain from those with myofascial pain syndromes (MPS) and active myofascial trigger points (MTrPs) and to assess whether self‐reports of mood, function, and health‐related quality of life differ between these groups.

Office-Based Elastographic Technique for Quantifying Mechanical Properties of Skeletal Muscle

Our objectives were to develop a new, efficient, and easy‐to‐administer approach to ultrasound elastography and assess its ability to provide quantitative characterization of viscoelastic properties of skeletal muscle in an outpatient clinical environment. We sought to show its validity and clinical utility in assessing myofascial trigger points, which are associated with myofascial pain syndrome.

Dry Needling Alters Trigger Points in the Upper Trapezius Muscle and Reduces Pain in Subjects With Chronic Myofascial Pain

To determine whether dry needling of an active myofascial trigger point (MTrP) reduces pain and alters the status of the trigger point to either a non–spontaneously tender nodule or its resolution.

Novel Use of Ultrasound Elastography to Quantify Muscle Tissue Changes After Dry Needling of Myofascial Trigger Points in Patients With Chronic Myofascial Pain

To compare a mechanical heterogeneity index derived from ultrasound vibration elastography with physical findings before and after dry‐needling treatment of spontaneously painful active myofascial trigger points in the upper trapezius muscle.

Airgun inter-pulse noise field during a seismic survey in an Arctic ultra shallow marine environment

Offshore oil and gas exploration using seismic airguns generates intense underwater pulses that could cause marine mammal hearing impairment and/or behavioral disturbances. However, few studies have investigated the resulting multipath propagation and reverberation from airgun pulses. This research uses continuous acoustic recordings collected in the Arctic during a low-level open-water shallow marine seismic survey, to measure noise levels between airgun pulses. Two methods were used to quantify noise levels during these inter-pulse intervals. The first, based on calculating the root-mean-square sound pressure level in various sub-intervals, is referred to as the increment computation method, and the second, which employs the Hilbert transform to calculate instantaneous acoustic amplitudes, is referred to as the Hilbert transform method. Analyses using both methods yield similar results, showing that the inter-pulse sound field exceeds ambient noise levels by as much as 9 dB during relatively quiet conditions. Inter-pulse noise levels are also related to the source distance, probably due to the higher reverberant conditions of the very shallow water environment. These methods can be used to quantify acoustic environment impacts from anthropogenic transient noises (e.g., seismic pulses, impact pile driving, and sonar pings) and to address potential acoustic masking affecting marine mammals.

Time domain formulation of the equivalent fluid model for rigid porous media.

A set of equations has been derived which corresponds to the time domain formulation of the equivalent fluid model. It models the propagation of an acoustic pulse in rigid frame porous material accounting for both viscous and thermal effects. It has been shown analytically and confirmed numerically that the equations can be reduced to those published previously in the limit of long and short duration pulses. Numerical solutions have been found for different pulse durations and the results have been compared with other time domain models.

Dynamics of soundscape in a shallow water marine environment: a study of the habitat of the Indo-Pacific humpback dolphin.

The underwater acoustic field is an important ecological element for many aquatic animals. This research examines the soundscape of a critically endangered Indo-Pacific humpback dolphin population in the shallow water environment off the west coast of Taiwan. Underwater acoustic recordings were conducted between late spring and late fall in 2012 at Yunlin (YL), which is close to a shipping lane, and Waisanding (WS), which is relatively pristine. Site-specific analyses were performed on the dynamics of the temporal and spectral acoustic characteristics for both locations. The results highlight the dynamics of the soundscape in two major octave bands: 150-300 Hz and 1.2-2.4 kHz. The acoustic energy in the former frequency band is mainly associated with passing container vessels near YL, while the latter frequency band is from sonic fish chorus at nighttime in both recording sites. In addition, large variation of low frequency acoustic energy throughout the study period was noticed at WS, where the water depths ranged between 1.5 and 4.5 m depending on tidal cycle. This phenomenon suggests that besides certain sound sources in the environment, the coastal soundscape may also be influenced by its local bathymetry and the dynamics of the physical environment.

Ultrasonic tissue characterization of the upper trapezius muscle in patients with myofascial pain syndrome

Myofascial trigger points (MTrPs) are palpable, tender nodules in skeletal muscle that produce symptomatic referred pain when palpated. MTrPs are characteristic findings in myofascial pain syndrome (MPS). The role of MTrPs in the pathophysiology of MPS is unknown. Objective characterization and quantitative measurement of the properties of MTrPs can improve their localization and diagnosis, as well as lead to clinical outcome measures. MTrPs associated with soft tissue neck pain are often found in the upper trapezius muscle. We have previously demonstrated that MTrPs can be visualized using ultrasound imaging. The goal of this study was to evaluate whether texture-based image analysis can differentiate structural heterogeneity of symptomatic MTrPs and normal muscle.

Elastography and tactile imaging for mechanical characterization of superficial muscles

Quantification of the mechanical properties of muscle is of significant clinical interest. Local changes in the mechanical properties of muscle are often associated with clinical symptoms. In particular, myofascial trigger points (MTrPs) are a very common, yet poorly understood and overlooked, cause of nonarticular musculoskeletal pain. MTrPs are localized, stiff, hyperirritable tender nodules, palpated in taut bands of skeletal muscle. Objective validated measures of the mechanical properties of MTrPs could potentially be a clinical outcome measure. We are investigating ultrasound shear wave elastography and tactile imaging as complementary objective methods to assess the mechanical properties of MTrPs. In an ongoing clinical study, we recruited 50 subjects (27 healthy controls and 23 with symptomatic chronic neck pain and active MTrPs). The upper trapezius muscles in these subjects were imaged using shear wave elastography using an external vibration source with varying frequency in the range [50–200] H...