Andrea J. Boon

Evidence-based guideline: Neuromuscular ultrasound for the diagnosis of carpal tunnel syndrome

Introduction: The purpose of this study was to develop an evidence‐based guideline for the use of neuromuscular ultrasound in the diagnosis of carpal tunnel syndrome (CTS). Methods: Two questions were asked: (1) What is the accuracy of median nerve cross‐sectional area enlargement as measured with ultrasound for the diagnosis of CTS? (2) What added value, if any, does neuromuscular ultrasound provide over electrodiagnostic studies alone for the diagnosis of CTS? A systematic review was performed, and studies were classified according to American Academy of Neurology criteria for rating articles of diagnostic accuracy (question 1) and for screening articles (question 2). Results: Neuromuscular ultrasound measurement of median nerve cross‐sectional area at the wrist is accurate and may be offered as a diagnostic test for CTS (Level A). Neuromuscular ultrasound probably adds value to electrodiagnostic studies when diagnosing CTS and should be considered in screening for structural abnormalities at the wrist in those with CTS (Level B). Muscle Nerve 46: 287–293, 2012

Snowboarder’s Talus Fracture Mechanism of Injury

Fracture of the lateral process of the talus is an injury unique to snowboarders and is of particular clinical relevance because it masquerades as an anterolateral ankle sprain and is difficult to detect on standard radiographic views. Misdiagnosis can lead to long-term morbidity in a young and active population, with ensuing severe degeneration of the subtalar joint. To date, the precise mechanism of injury has not been established, making it difficult to identify potential preventive strategies in equipment design or snowboarding technique. Fracture of the lateral process of the talus in snowboarders has been thought to result from pure dorsiflexion and inversion combined with axial loading. We hypothesized, however, that external rotation is a key component of the mechanism of injury. Ten cadaveric ankles were mounted on a materials testing machine in a position of fixed dorsiflexion and inversion. All ankles were loaded to failure axially, with or without combined external rotation. No fractures occurred after axial loading in dorsiflexion and inversion, but six of eight specimens sustained fractures of the lateral process of the talus when similarly loaded with external rotation added, supporting our hypothesis. Further study is needed to evaluate the relationship between various types of snowboarding equipment and fracture mechanism.

Two‐dimensional ultrasound imaging of the diaphragm: Quantitative values in normal subjects

Introduction: Real time ultrasound imaging of the diaphragm is an under‐used tool in the evaluation of patients with unexplained dyspnea or respiratory failure. Methods: We measured diaphragm thickness and the change in thickness that occurs with maximal inspiration in 150 normal subjects, with results stratified for age, gender, body mass index, and smoking history. Results: The lower limit of normal diaphragm thickness at end expiration or functional residual capacity is 0.15 cm, and an increase of at least 20% in diaphragm thickness from functional residual capacity to total lung capacity is normal. A side to side difference in thickness at end expiration of > 0.33 cm is abnormal. Diaphragm thickness and contractility are minimally affected by age, gender, body habitus, or smoking history. Conclusions: This study confirms previous findings in much smaller groups of normal controls for quantitative ultrasound of the diaphragm and provides data that can be applied widely to the general population. Muscle Nerve 47: 884–889, 2013

Ultrasound‐guided needle EMG of the diaphragm: Technique description and case report

We describe an ultrasound (US)‐guided technique for needle examination of the diaphragm and report a case in which the adjuvant use of diagnostic US in conjunction with electrophysiologic studies provided additional information regarding the motion of the diaphragm in a patient who was a potential candidate for phrenic nerve pacing. US imaging provides excellent direct and real‐time visualization of soft tissue, anatomic landmarks, fascial planes, and neurovascular structures. It thereby enhances safety by avoiding accidental needle puncture of vital organs, and it also increases the diagnostic utility of the needle examination. Muscle Nerve 38: 1623–1626, 2008

Efficacy of Intra-Articular Botulinum Toxin Type A in Painful Knee Osteoarthritis: A Pilot Study

To evaluate the efficacy and safety of botulinum toxin type A (BoNT‐A) injected intra‐articularly in 60 subjects with moderate pain and functional impairment secondary to knee osteoarthritis. The study investigators hypothesized that intra‐articular BoNT‐A would result in statistically significant improvements in pain and function at 8 weeks.

Expedited Wound Healing with Noncontact, Low-frequency Ultrasound Therapy in Chronic Wounds: A Retrospective Analysis

OBJECTIVE: To evaluate the clinical role of noncontact, low-frequency ultrasound therapy (MIST Therapy System; Celleration, Eden Prairie, Minnesota) in the treatment of chronic lower-extremity wounds. DESIGN: A retrospective observational study. SETTING: A multidisciplinary, vascular wound-healing clinic. PATIENTS: One hundred sixty-three patients who received MIST Therapy plus standard of care (treatment group) and 47 patients who received the standard of care alone (control group). INTERVENTIONS: All wounds in the control and treatment groups received the standard of wound care and were followed for 6 months. In the treatment group, MIST Therapy was administered to wounds 3 times per week for 90 days or until healed. MAIN OUTCOME MEASURES: Proportion of wounds healed and wound volume reduction. Rate of healing was also quantified using 1-way analysis of variance to determine the slope of the regression line from starting volume to ending volume, where a steeper slope indicates a faster healing rate. Outcomes were evaluated in all wounds and etiology-specific subgroups. MAIN RESULTS: A significantly greater percentage of wounds treated with MIST Therapy and standard of care healed as compared with those treated with the standard of care alone (53% vs 32%; P = 0.009). The slope of the regression line in the MIST arm (1.4) was steeper than the slope in the control arm (0.22; P = .002), indicating a faster rate of healing in the MIST-treated wounds. CONCLUSION: The rate of healing and complete closure of chronic wounds in patients improved significantly when MIST Therapy was combined with standard wound care.

Sonography in carpal tunnel syndrome

Introduction: Our objective in this study was to assess the diagnostic utility of the median nerve cross‐sectional area (CSA) at the wrist, the wrist–forearm ratio, and the wrist–forearm difference in patients with and without carpal tunnel syndrome (CTS). Methods: Individuals with electrodiagnostically proven CTS and asymptomatic control subjects were recruited prospectively from among patients referred to our electrodiagnostic laboratory. Blinded measurements of CSA were made from transverse sonographic images of the median nerve at the wrist (pisiform) and mid‐forearm. Results: Fifty‐five cases and 49 controls were recruited. Wrist median nerve CSA (15 vs. 9 mm2; P < 0.0001), wrist–forearm ratio (3.09 vs. 1.90 mm2; P < 0.0001), and wrist–forearm difference (10 vs. 4 mm2; P < 0.0001) were all significantly larger in CTS cases (areas under the curve = 0.89, 0.82, and 0.88, respectively). Conclusions: Median nerve CSA at the carpal tunnel inlet and wrist–forearm difference provides the best discrimination between patients with CTS and controls according to receiver operator characteristic (ROC) analysis. Age, gender, height, weight, and wrist size have no effect on CSA. Muscle Nerve, 2011

Motor Evoked Potential Monitoring during Cryoablation of Musculoskeletal Tumors

PURPOSE To describe the use of intraprocedural motor evoked potential (MEP) monitoring to minimize risk of neural injury during percutaneous cryoablation of perineural musculoskeletal tumors. MATERIALS AND METHODS A single-institution retrospective review of cryoablation procedures performed to treat perineural musculoskeletal tumors with the use of MEP monitoring between May 2011 and March 2013 yielded 59 procedures to treat 64 tumors in 52 patients (26 male). Median age was 61 years (range, 4-82 y). Tumors were located in the spine (n = 27), sacrum (n = 3), retroperitoneum (n = 4), pelvis (n = 22), and extremities (n = 8), and 21 different tumor histologies were represented. Median tumor size was 4.0 cm (range, 0.8-15.0 cm). Total intravenous general anesthesia, computed tomographic guidance, and transcranial MEP monitoring were employed. Patient demographics, tumor characteristics, MEP findings, and clinical outcomes were assessed. RESULTS Nineteen of 59 procedures (32%) resulted in decreases in intraprocedural MEPs, including 15 (25%) with transient decreases and four (7%) with persistent decreases. Two of the four patients with persistent MEP decreases (50%) had motor deficits following ablation. No functional motor deficit developed in a patient with transient MEP decreases or no MEP change. The risk of major motor injury with persistent MEP changes was significantly increased versus transient or no MEP change (P = .0045; relative risk, 69.8; 95% confidence interval, 5.9 to > 100). MEP decreases were 100% sensitive and 70% specific for the detection of motor deficits. CONCLUSIONS Persistent MEP decreases correlate with postprocedural sustained motor deficits. Intraprocedural MEP monitoring helps predict neural injury and may improve patient safety during cryoablation of perineural musculoskeletal tumors.

Complications of needle electromyography: Hematoma risk and correlation with anticoagulation and antiplatelet therapy

Electromyography (EMG) is considered a relatively safe procedure based primarily on clinical experience. Literature review reveals few reported complications from bleeding or hematoma formation. No evidence‐based guidelines exist for EMG procedures in patients who are taking anticoagulant or antiplatelet medications. The purpose of this study was to determine if patients taking anticoagulant or antiplatelet agents exhibit an increased risk of hematoma formation after routine needle EMG of the tibialis anterior muscle when compared to controls. Study subjects underwent routine needle EMG of the tibialis anterior muscle followed by ultrasound examination to evaluate for the presence of hematoma formation. A mean of 30.8 min elapsed between needle insertion and ultrasound evaluation. A total of 101 patients who were taking warfarin were studied. They had International Normalized Ratio (INR) values at or above 1.5, and two were found to have small, subclinical hematomas. Of 57 patients taking clopidogrel and/or aspirin, 1 was found to have a small, subclinical hematoma. In the control group (51 patients taking neither class of medication), no hematomas were found on ultrasound. This study suggests that hematoma formation from a standard needle EMG is rare. In addition, hematoma formation in our study group of patients on anticoagulant or antiplatelet medications was also uncommon, and no patients with documented hematomas experienced symptoms. These findings should be considered when determining the feasibility of electrodiagnostic evaluation of patients who are taking anticoagulant or antiplatelet medications. Muscle Nerve, 2008

Hematoma risk after needle electromyography.

Introduction: Although needle electromyography (EMG) appears to be a relatively safe procedure based primarily on clinical experience, no evidence‐based guidelines exist for EMG procedures in patients taking anticoagulant or antiplatelet medications. We sought to determine whether there is an increased risk of hematoma formation after EMG of potentially high‐risk muscles in patients taking anticoagulant or antiplatelet agents. Methods: After undergoing routine EMG, if any of seven predetermined high‐risk muscles were tested, study subjects then underwent ultrasound to evaluate for hematoma formation. Results: Patients were divided into three groups based on medication (warfarin, aspirin/clopidogrel, no blood‐thinning medication), with at least 100 muscles examined per group. Two small, subclinical hematomas were seen on ultrasound; there was no difference in hematoma risk between groups (P = 0.43). Conclusions: Our findings suggest that hematoma formation from standard needle EMG is rare even in high‐risk muscles, which have been avoided historically in anticoagulated patients. Muscle Nerve 45: 9–12, 2012