Establishing Reference Values in the Neuromuscular Ultrasound Laboratory Using the e-Norms Method: A Feasibility...

Area of Science:

• Neuromuscular Ultrasound
• Diagnostic Imaging
• Reference Value Establishment

Background:

• Standard neuromuscular lab reference values require healthy controls, but nerve size varies and muscle echo intensity (EI) is device-specific.
• Establishing reliable reference values is crucial for accurate diagnosis in neuromuscular diseases.

Purpose of the Study:

• To derive reference values using the e-norms method by extrapolating from a studied sample.
• To compare these derived values with existing published reference values.
• To assess the diagnostic accuracy of muscle EI in differentiating myopathic conditions.

Main Methods:

• Retrospective analysis of nerve and muscle ultrasound data from 2018-2023 at a tertiary referral center.
• Plotting nerve cross-sectional area (CSA) and muscle EI, deriving statistics from the e-norms curve plateau.
• Comparing nerve size reference values and using receiver operator characteristics curves for muscle EI diagnostic accuracy.

Main Results:

• Analysis included 1124 nerves and 1154 muscles from 109 and 99 subjects, respectively.
• Derived nerve CSA reference values showed concordance with other studies, particularly for leg nerves.
• Muscle EI, using e-norms, achieved 85% sensitivity and 92% specificity in discriminating myopathic from healthy subjects.

Conclusions:

• The e-norms method is a feasible and effective approach for establishing reference values in neuromuscular ultrasound laboratories.
• This method aids in accurate diagnosis and management of neuromuscular disorders.