Boon, Andrea J.

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.

ABSTRACTIntroductionWe sought to determine the specificity of compound muscle action potential (CMAP) durations and amplitudes in a large critical illness neuromyopathy (CINM) cohort relative to controls with other neuromuscular conditions.MethodsFifty‐eight patients with CINM who had been seen over a 17‐year period were retrospectively studied. Electrodiagnostic findings of the CINM cohort were compared with patients with axonal peripheral neuropathy and myopathy due to other causes.ResultsMean CMAP durations were prolonged, and mean CMAP amplitudes were severely reduced both proximally and distally in all nerves studied in the CINM cohort relative to the control groups. The specificity of prolonged CMAP durations for CINM approached 100% if they were encountered in more than 1 nerve.DiscussionProlonged, low‐amplitude CMAPs occur more frequently and with greater severity in CINM patients than in neuromuscular controls with myopathy and axonal neuropathy and are highly specific for the diagnosis of CINM. Muscle Nerve 57: 395–400, 2018

ABSTRACTIntroductionCranial muscle fasciculations may be difficult to detect in amyotrophic lateral sclerosis (ALS). Ultrasound (US) detection of fasciculations in these muscles may have clinical utility.MethodsPatients with suspected ALS were prospectively enrolled. Nerve conduction studies, needle electromyography (EMG), and US examination of cranial muscles were performed. Controls were examined by US only. Fasciculations were counted and scored for each muscle after 10 or 30 seconds.ResultsThere were 84 patients with ALS. Fasciculations were most frequently found in the genioglossus muscle. Overall, detection rates by US and EMG were similar, but US was more likely to detect frequent fasciculations. Fasciculations were rare in controls, seen in 7 of 1,090 (0.6%) muscles. No control had > 5 fasciculations in any muscle.DiscussionFasciculations were frequently detected in cranial muscles of patients with ALS. US was found to be a sensitive method, and was not impaired by factors such as anxiety and the inability of the patient to relax. Muscle Nerve 56: 1072–1076, 2017

ABSTRACTIntroductionUltrasound is increasingly used as an adjunct in the diagnosis of neuromuscular disease by measuring muscle thickness and echointensity (EI). Reproducibility is limited because of variations in scanning technique and proprietary algorithms that alter EI values.MethodsWe developed a standardized scanning protocol and a portable machine without any postimaging processing. Ten subjects underwent scanning of 6 muscles by 3 sonographers on 2 separate days. One of the sonographers repeated the protocol with 4 different machine/transducer combinations. Gray‐scale values were measured from each image with the use of a region of interest (ROI) box.ResultsCombined intraclass correlation coefficients were 0.92 (intra‐rater), 0.88 (inter‐rater), and 0.96 (inter‐system). The biceps had the highest variability (coefficient of variance [COV] 12.7%), and the medial gastrocnemius had the lowest variability (COV 7.4%).ConclusionsWe demonstrate excellent reliability of a reproducible ultrasound system for gray‐scale analysis of muscle that has potential applicability as a screening tool for neuromuscular disease. Muscle Nerve 56: 408–412, 2017

ABSTRACTIntroduction: Needle electromyography (EMG) of the diaphragm carries the potential risk of pneumothorax. Knowing the approximate depth of the diaphragm should increase the test's safety and accuracy. Methods: Distances from the skin to the diaphragm and from the outer surface of the rib to the diaphragm were measured using B mode ultrasound in 150 normal subjects. Results: When measured at the lower intercostal spaces, diaphragm depth varied between 0.78 and 4.91 cm beneath the skin surface and between 0.25 and 1.48 cm below the outer surface of the rib. Using linear regression modeling, body mass index (BMI) could be used to predict diaphragm depth from the skin to within an average of 1.15 mm. Conclusions: Diaphragm depth from the skin can vary by more than 4 cm. When image guidance is not available to enhance accuracy and safety of diaphragm EMG, it is possible to reliably predict the depth of the diaphragm based on BMI. Muscle Nerve 49: 666–668, 2014

ABSTRACTIntroduction: Neuromuscular ultrasound (NMUS), an emerging diagnostic subspecialty field, has become an important extension of the electrodiagnostic examination. However, there are no formal guidelines on how to appropriately report NMUS results. Methods: The AANEM convened an expert panel to develop recommendations for reporting NMUS findings. Results: Providers should describe the reason for referral, the nerves or muscles studied, and normal values as well as numerical values for the results of imaging. Muscle imaging reports should also include a description of how gray‐scale values were calculated. NMUS‐guided needle placement reports should include a description of the length and gauge of needle, the type of probe used, and an indication of how well the patient tolerated the procedure. All reports should clearly state whether the findings were normal or abnormal and include a definitive diagnosis. Conclusions: NMUS reports should provide comprehensive information along with a succinct conclusion, mirroring guidelines for electrodiagnostic reports. Muscle Nerve, 2013