Diagnostic neuromuscular ultrasound to confirm clinical significance of a genetic variant for Charcot-Marie-Tooth type 4C: A case report.

ABSTRACT: Neuromuscular ultrasound (NMUS) has emerged as a beneficial, complementary tool to EMG in the diagnosis of neuromuscular diseases as it provides high-resolution anatomic imaging of peripheral nerves and muscles. It has been used previously as an adjunct to EMG to diagnose Charcot-Marie-Tooth disease (CMT). Here, we present a case of a 64-year-old male with bilateral sensorineural hearing loss of 14 years who presented to an outpatient neuromuscular clinic at a tertiary medical center with very slow progressive paresthesias. This case highlights the application of NMUS to help confirm the presence of a likely CMT type 4C despite indeterminate genetic testing results and challenging EMG results. He had genetic testing which revealed a normal PMP22 gene; however, he had a variant of uncertain significance (VUS) in the SH3TC2 gene which has shown associations with autosomal recessive CMT4C. NMUS revealed mild median and significant tibial nerve uniform enlargement throughout their course. There may also be utility in performing NMUS on similarly affected family members if the same VUS returns for SH3TC2, with consideration of both peripheral nerve and nerve root assessment.

Ultrahigh-frequency ultrasound of fascicles in the common fibular, superficial fibular, and sural nerves.

INTRODUCTION/AIMS: While ultrasound assessment of cross-sectional area and echogenicity has gained popularity as a biomarker for various neuropathies, there is a scarcity of data regarding fascicle count and density in neuropathies or even healthy controls. The aim of this study was to determine whether fascicles within select lower limb nerves (common fibular, superficial fibular, and sural nerves) can be counted in healthy individuals using ultrahigh-frequency ultrasound (UHFUS). METHODS: Twenty healthy volunteers underwent sonographic examination of the common fibular, superficial fibular, and sural nerves on each lower limb using UHFUS with a 48 MHz linear transducer. Fascicle counts and density in each examined nerve were determined by a single rater. RESULTS: The mean fascicle number for each of the measured nerves included the following: common fibular nerve 9.85 (SD 2.29), superficial fibular nerve 5.35 (SD 1.59), and sural nerve 6.73 (SD 1.91). Multivariate linear regression analysis revealed a significant association between cross-sectional area and fascicle count for all three nerves. In addition, there was a significant association seen in the common fibular nerve between fascicle density and height, weight, and body mass index. Age and sex did not predict fascicle count or density (all p > .13). DISCUSSION: UHFUS enabled the identification and counting of fascicles and fascicle density in the common fibular, superficial fibular, and sural nerves. Knowledge about normal values and normal peripheral nerve architecture is needed in order to further understand and identify pathological changes that may occur within each nerve in different disease states.

Mechanisms and Uses of Dietary Therapy as a Treatment for Epilepsy: A Review.

One-third of patients with epilepsy do not respond to antiepileptic drugs and may seek complementary and alternative treatment modalities. Dietary therapies such as the ketogenic diet (KD), the modified Atkins, the medium-chain triglyceride, and the low glycemic index diet have been successfully implemented in some forms of epilepsy and are growing in utilization. The KD is a high-fat, low-protein, low-carbohydrate diet that has been used for various conditions for over a century. Insights into the mechanism of action of these diets may provide more targeted interventions for patients with epilepsy. Knowledge of these mechanisms is growing and includes neuroprotective effects on oxidative stress, neuroinflammation, potassium channels in the brain, and mitochondrial function.