Kevin R. Volz

Relationship Between Intraneural Vascular Flow Measured With Sonography and Carpal Tunnel Syndrome Diagnosis Based on Electrodiagnostic Testing

The purpose of this study was to document and analyze intraneural vascular flow within the median nerve using power and spectral Doppler sonography and to determine the relationship of this vascular flow with diagnosis of carpal tunnel syndrome based on electrodiagnostic testing.

Morphologic Characterization of Intraneural Flow Associated With Median Nerve Pathology

A prospective cohort of 47 symptomatic patients who reported for nerve conduction studies and 44 asymptomatic controls was examined with sonography to evaluate the median nerve. Doppler studies of the median nerve were collected with handheld sonography equipment and a 12-MHz linear broadband transducer. Strict inclusion criteria were established for assessing 435 waveforms from 166 wrists. Two sonographers agreed that 245 waveforms met the a priori criteria and analyzed the corresponding data. Spectral Doppler waveforms provided direct quantitative and qualitative data for comparison with indirect provocative testing results. These Doppler data were compared between the recruitment groups. No statistical difference existed in waveforms between the groups (P < .05). Trending of the overall data indicated that as the number of positive provocative tests increased, the mean peak systolic velocity within the carpal tunnel (mid) also increased, whereas the proximal mean peak systolic velocity decreased. However, by using multiple provocative tests as an indirect comparative measure, researchers may find mean peak spectral velocity at the carpal tunnel inlet a helpful direct measure in identifying patients with carpal tunnel syndrome.

Use of contrast-enhanced sonography to investigate intraneural vascularity in a cohort of Macaca fascicularis with suspected median mononeuropathy.

The purpose of this study was to provide clinical evidence of the use of contrast‐enhanced sonography in detecting and quantifying changes in intraneural vascularity due to median mononeuropathy.

Carpal tunnel syndrome severity staging using sonographic and clinical measures

Ultrasonography may be valuable in staging carpal tunnel syndrome severity, especially by combining multiple measures. This study aimed to develop a preliminary severity staging model using multiple sonographic and clinical measures.

A Mixed-Method Approach to Evaluating the Association Between Myofascial Trigger Points and Ankle/Foot Pain Using Handheld Sonography Equipment A Pilot Study

This mixed-method blinded research study used high-frequency diagnostic medical sonography (DMS) to document myofascial trigger points (MTrPs) associated with ankle/foot pain. A total of 17 symptomatic and 8 asymptomatic participants provided 500 MTrP areas for palpation. Forty-nine of these MTrP areas (including 16 tender points, 15 palpable MTrPs, and 18 palpated and imaged MTrPs) were compared with the patient’s ankle/foot pain, collected with the SF-12 Health Survey, Victorian Institute of Sports Assessment–Achilles questionnaire, and a visual analog scale. Qualitative analyses of the participants’ histories were used to understand the context of the data collected. The mean area of the 18 imaged MTrPs was 0.09 cm2, and they appeared inhomogeneous and hypoechoic. Those with right-sided MTrPs were statistically significant for those with reported pain. Participants with left-sided MTrPs did not demonstrate a significant correlation to reported pain. The results demonstrated a promising possible diagnostic approach using sonography to evaluate MTrPs in the ankle/foot for documenting myofascial pain. In addition, elastography and transducer frequencies >12 MHz are proposed as a DMS technique to increase overall diagnostic yield.

Longitudinal Design for Sonographic Measurement of Median Nerve Swelling with Controlled Exposure to Physical Work Using an Animal Model

In the study described here, we examined the feasibility of a longitudinal design to measure sonographically swelling of the median nerve caused by controlled exposure to a work task and to evaluate the relationship of changes in morphology to diagnostic standards. Fifteen macaques, Macaca fascicularis, pinched a lever in various wrist positions at a self-regulated pace (8 h/d, 5 d/wk, 18-20 wk). Nerve conduction velocity (NCV) and cross-sectional area (CSA) were measured every 2 wk from baseline through working and a 6-wk recovery. Trending across all subjects revealed that NCV slowed and CSA at the carpal tunnel increased in the working arm, whereas no changes were observed in CSA either at the forearm or for any measure in the non-working arm. There was a small negative correlation between NCV and CSA in the working arm. This study provides validation that swelling can be observed using a longitudinal design. Longitudinal human studies are needed to describe the trajectory of nerve swelling for early identification of median nerve pathology.

Klippel-Trénaunay Syndrome Need for Careful Clinical Classification

Klippel‐Trénaunay syndrome (KTS) is a rare congenital malformation characterized by a triad of clinical presentations: (1) capillary malformations manifesting as a “port wine stain”; (2) limb hypertrophy; and (3) venous varicosities. It is distinguished from Parkes‐Weber syndrome by the absence of substantial arteriovenous shunting. Due to the clinical implications of an arteriovenous fistula, differentiation between the two syndromes is important, as the prognosis and treatment greatly differ. We present a series of 5 cases of suspected KTS, while emphasizing the difficulties in distinguishing KTS from Parkes‐Weber syndrome without diagnostic imaging and underscoring the importance of accurately classifying patients with the appropriate syndrome.

Longitudinal Analysis of Median Nerve Perfusion Using Spectral Doppler in a Working Animal Model

Carpal tunnel syndrome (CTS) is a form of median mononeuropathy (MMN) of the wrist that has become the most common nerve entrapment syndrome of the upper limbs. During the acute phase of CTS, the median nerve becomes hyperemic and enlarged as it begins to be compressed by the transverse carpal ligament; however, continual compression ultimately leads to median nerve ischemia. The objective of this study was to longitudinally quantify the amount of perfusion of the median nerve using spectral Doppler in a working animal model, as the cohort prospectively increased their risk of MMN through a repetitive pinching task. The results of the study provided low-level evidence that the use of spectral Doppler to accurately detect longitudinal changes in vascularity within the median nerve may be diagnostically inadequate. As the subjects in the study moved through the working and nonworking stages of study, spectral Doppler alone proved to lack the level of sensitivity needed to detect physiologic changes within the nerve. This outcome, although inconclusive when it comes to detecting changes in median nerve vascularity, does suggest the need for this method to be analyzed in conjunction with other sonographic features and provocative testing.

Establishing an Imaging Protocol for Detection of Vascularity within the Median Nerve Using Contrast-Enhanced Ultrasound

This preclinical study was conducted to develop discrete sonographic instrumentation settings and also safe contrast dosing that would consistently demonstrate perineural vascularity along the median nerve. This set of imaging studies was conducted with a convenience cohort of young adult female monkeys (Macaca fascicularis). Sonographic equipment settings and dosing were refined throughout the imaging series to ensure consistent contrast-enhanced ultrasound imaging. A mechanical index of 0.13 was consistently used for imaging. Perineural vessels were imaged with a suspension solution of 0.04 mL Definity/0.96 mL saline introduced over 5 minutes for a total dose of 0.8 mL of contrast solution. Blinded studies of high and low dose contrast, along with saline injections, were correctly identified by two experienced sonographers. This preclinical study established adequate equipment settings and dosing that allowed for a valid demonstration of vascularity surrounding the median nerve.

Utilization of Sonography Compared With Magnetic Resonance Imaging in Determining the Cross-Sectional Area of the Median Nerve in a Sample of Working Macaca fascicularis A Preclinical Study

A preclinical study of 15 Macaca fascicularis monkeys was conducted to determine (1) the ability of detecting median mononeuropathy (MMN) within the median nerve after a work intervention and (2) the relationship between the layers of the median nerve during an acute inflammatory process by using sonography in conjunction with magnetic resonance imaging (MRI). Cross-sectional areas (CSAs) were imaged using MRI and sonography proximal to the carpal tunnel inlet (defined by the most distal portion of the radius) and further distal into the carpal tunnel (defined by the most proximal portion of the pisiform) at the prework exposure stage. CSAs measured on the outer edge of the median nerve were obtained from both modalities, at both anatomical locations. An intermodality t test demonstrated no statistical differences between the two sets of measurements (radius, P ≤ .15; pisiform, P ≤ .46). At the postwork exposure stage, sonographic measurements were obtained on the outer and inner borders of the median nerve at both anatomical levels. A two-tailed t test showed statistically significant differences within the carpal tunnel comparing pre- and postwork CSA measurements (radius, P ≤ .01; pisiform, P ≤ .297). The epineurial layer area was then determined as the difference between outer-border and inner-border CSAs. Pearson correlations between the epineurial layer and overall median nerve CSA within the carpal tunnel demonstrated a strong positive correlation that was statistically significant (r = 0.97; P ≤ .01) after postwork exposure. Possible factors contributing to this acute phase of MMN could be hyperemia within the layers of the nerve and the development of Renault bodies. This work would need to be translated to human studies for further confirmation of the anatomic and clinical significance of this effect.