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As a complement to electromyography (EMG) and Nerve Conduction Studies (NCS), neuromuscular ultrasound (NMUS) is rapidly becoming a standard modality for the diagnosis and treatment of neuromuscular disorders. Also called muscular-skeletal (MSK) or neuro ultrasound, NMUS provides dynamic, high-resolution images of muscles, tendons, ligaments, nerves, and other soft tissues in the body. Unlike MRI or CT scans, NMUS allows clinicians to perform non-invasive, real-time evaluations of muscles and nerves at the bedside, on the sports field, or in remote locations. In conjunction with EMG and NCS studies, NMUS can increase diagnostic capabilities in a non-invasive, painless manner. In addition, they offer real-time ultrasound guidance for needle placement (EMGs, biopsies, injections) in a clinical or outpatient setting.
Neuromuscular ultrasound may be new for many neurologists, physiatrists, and other health professionals focused on neuromuscular disorders, and the technology continues to advance, presenting many new features to consider for EMG professionals. When incorporating NMUS into their practice or upgrading an existing NMUS system, clinicians must understand the essential features and capabilities required to utilize NMUS to its greatest advantage.
Neuromuscular ultrasound is the ideal adjunctive modality to provide invaluable anatomic correlation to EMG physiology
Jeffrey Strakowski, MD.
Clinical Professor, Department of Physical Medicine and Rehabilitation, Ohio State University School of Medicine
The higher the image quality, the more precise the clinical assessment and intervention. Given the complexity and variety of neuromuscular disorders, any NMUS device must offer range frequencies (2 – 18 MHz ) required to best access different anatomical depths. Other features, such as a large image viewing area and a zoom function to enlarge images, will provide clinicians with greater detail and versatility.
Natus InVisus Pro scan – Flexor Pollicis Short Axis
NMUS devices should have several different display modes:
Transducers play the most significant role when using neuromuscular ultrasound. A higher transducer frequency (18 MHz) results in better superficial (near-surface) images, such as nerves closer to the skin. A lower transducer frequency (2 – 5 MHz) results in better deep-structure images, penetrating deeper for clear images of structures such as sciatic nerve or hip muscles. Clinicians can adjust the frequency depending on the issue, making it easy to view both muscle and nerve structures during the same examination.
Transducers come in various shapes and frequencies, each tailored to visualize specific depths and types of tissue. Any NMUS system should include a range of linear, convex (curvilinear), and specialty transducers. Linear transducers are typically more flexible and can be used in various positions. Depending on the situation and clinician preferences, convex transducers may be better for deeper examinations. The unique design of specialty transducers provides higher resolution and can help assess superficial anatomies or structures that are more difficult to access.
Invisus Pro is a compact solution offering actionable information at the point of care.
For many reasons, POC technology is becoming increasingly important for immediate diagnostic results, improving the patient experience, reducing wait times, and streamlining treatment. Portable, lightweight, battery-operated NMUS devices can be used at the bedside, for outpatient examinations, or in remote settings. Tablet-based NMUS devices should fit easily in a clinician’s pocket to ensure mobility and accelerate assessments and diagnoses.
POC assessments via NMUS offer faster diagnosis and treatment consideration when other electrodiagnostic modalities are unavailable or cannot be used. High-performance neuro ultrasound diagnostics may be more accessible to practices in remote or rural areas, offering greater diagnostic capability, safer needle interventions, and real-time monitoring of the patient’s condition.
We can miss important structural information with electrodiagnostic studies, which can remain normal during the first few weeks of nerve injury. That’s where ultrasound can be beneficial. It’s also safe, widely available and relatively inexpensive.
Natalia Gonzalez, MD
Assistant Professor of Neurology, Duke University
Advanced NMUS technology should offer an intuitive interface and easy-to-use controls to minimize the learning curve and help clinicians navigate the system quickly and efficiently when in use. A crucial component in the design of the NMUS device is a responsive touchscreen to facilitate immediate adjustments and swift access to different modes and features.
A robust NMUS interface should present the following:
Clinicians may utilize different EMG systems, so NMUS devices that can keep clinicians from being tethered to brand-specific software. This can often help provide a more cost-effective solution that still meets their unique needs and preferences. This interoperability lowers costs and ensures continuity of care by allowing the use of existing systems and avoiding expensive upgrades or conversions. Devices should have the capability to be docked and used concurrently with most EMG or NCS systems or be used independently while offering seamless uploading of images later.
Neuromuscular technology should provide versatility, portability, and the ability to be used autonomously in various clinical settings and with various EMG systems and software.
In addition to interoperability with different EMG systems, neuromuscular ultrasound tools should offer the ability to perform measurements and annotate images and other reports easily. NMUS technology should utilize the fastest processing times possible to improve responsiveness, save time during examination, and support the clinician’s experience.
Information and reports must be high quality, easy to understand, clinically actionable, and available at the point-of-care. Specific features to look for in this category include:
Selecting the right neuromuscular ultrasound technology can improve health outcomes, enhance the patient’s experience, and lower overall costs. With the right NMUS solution, neurologists, physiatrists, and other clinicians can harness the power of neuromuscular ultrasound to deliver diagnoses and monitor treatments more efficiently, accurately, and safely.
Sources:
1. Walker FO, Cartwright MS, Alter KE, Visser LH, Hobson-Webb LD, Padua L, Strakowski JA, Preston DC, Boon AJ, Axer H, van Alfen N, Tawfik EA, Wilder-Smith E, Yoon JS, Kim BJ, Breiner A, Bland JDP, Grimm A, Zaidman CM. Indications for neuromuscular ultrasound: Expert opinion and review of the literature. Clin Neurophysiol. 2018 Dec;129(12):2658-2679. doi: 10.1016/j.clinph.2018.09.013. Epub 2018 Sep 25. PMID: 30309740.
2. Jin TG, D’Andrea D, Ajroud-Driss S, Franz CK. The accuracy of needle electrode placement by trainees in selected forearm muscles using verification by neuromuscular ultrasound. J Electromyogr Kinesiol. 2021 Oct;60:102573. doi: 10.1016/j.jelekin.2021.102573. Epub 2021 Jul 10. PMID: 34273729.
3. Gonzalez NL, Hobson-Webb LD. Neuromuscular ultrasound in clinical practice: A review. Clin Neurophysiol Pract. 2019 Jul 12;4:148-163. doi: 10.1016/j.cnp.2019.04.006. PMID: 31886438; PMCID: PMC6921231.
4. Hommel AL, Cartwright MS, Walker FO. The use of ultrasound in neuromuscular diagnoses. Neurol Clin Pract. 2017 Jun;7(3):266-273. doi: 10.1212/CPJ.0000000000000368. PMID: 30107010; PMCID: PMC6081967.
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