Table 1.

Ultrasound Findings in Polyneuropathies and Motor Neuron Diseases

Condition	Key Ultrasound Findings
Charcot-Marie Tooth Disease	Demyelinating forms have CSAs 2.0-4.0× that of controls in the median and ulnar nerves. Axonal forms have CSA 1.5-2.0× that of controls in the median and ulnar nerves. The sural nerve is only enlarged in children.
Multifocal Motor Neuropathy	Patchy increased CSA with inter- and intra-nerve variability; includes the brachial plexus Focal nerve enlargements can differentiate MMN from ALS Nerve enlargement does not correlate well with conduction block
Guillain-Barre Syndrome	Nerves may be enlarged before changes are detected by electrodiagnosis Nerve enlargement is reversible with recovery
Chronic Inflammatory Demyelinating Polyneuropathy	Patchy nerve enlargement The site of focal enlargement does not always correlate with slowed conduction velocity
Diabetic Polyneuropathy	Nerve changes are subtle and not particularly helpful for diagnosis Intrinsic foot muscle atrophy can be readily detected
Vasculitic Polyneuropathy	Minor increase in nerve CSA Can guide selection of nerve biopsy site
Amyloid Polyneuropathy	No standard abnormalities yet defined
Acromegaly	Diffuse enlargement of nerve CSA
Leprosy	Ulnar nerve CSA enlargement Increased epineurial thickness Increased vascularity
Spinal Muscular Atrophy	Patchy increase in muscle echotexture Increased subcutaneous tissue thickness
Amyotrophic Lateral Sclerosis	Normal to slightly decreased nerve CSA Muscle atrophy and increased echogenicity Ultrasound is more sensitive for the detection of fasciculations than visual inspection or EMG Diaphragm thinning and increased echogenicity May be a responsive biomarker of disease progression