Cervical root sonography to differentiate multifocal motor neuropathy from ALS

Area of Science:

• Neurology
• Neurophysiology
• Medical Imaging

Background:

• Multifocal motor neuropathy (MMN) is a rare autoimmune disorder affecting peripheral nerves.
• Diagnosis of MMN often relies on electrophysiological evidence of conduction block, which may not always be present.
• Proximal nerve root abnormalities may indicate MMN even without overt conduction block.

Purpose of the Study:

• To investigate sonographical evidence of focal proximal demyelination in MMN.
• To assess the utility of ultrasound in diagnosing MMN when conduction block is absent.
• To compare cervical nerve root dimensions in MMN patients versus ALS patients and healthy controls.

Main Methods:

• Sonographical assessment of cervical nerve roots (C5, C6) was performed.
• Study included 9 MMN patients, 22 Amyotrophic Lateral Sclerosis (ALS) patients, and 17 control subjects.
• Mean nerve root diameters were measured and compared between groups.

Main Results:

• MMN patients exhibited significantly larger mean diameters of C5 and C6 nerve roots compared to ALS patients and controls.
• Nerve root enlargement was more pronounced on the clinically affected side in MMN patients.
• Sonographical findings were non-specific but showed a trend towards increased nerve root size in MMN.

Conclusions:

• Sonography of cervical nerve roots may reveal suggestive evidence of focal proximal demyelination in MMN.
• Ultrasound can be a valuable adjunctive diagnostic tool for MMN, particularly when conduction block is not evident.
• This imaging technique may support the diagnosis of MMN, aiding clinicians in identifying affected individuals earlier.