Onion-bulb patterns predict acquired or inherited demyelinating polyneuropathy.

Area of Science:

• Neuropathology
• Nerve Biopsy Analysis
• Demyelinating Diseases

Background:

• Onion-bulbs (OB) are characteristic Schwann cell changes in demyelinating polyneuropathies.
• OBs occur in both inherited and acquired forms of these nerve disorders.
• Understanding OB patterns may help differentiate neuropathy types.

Purpose of the Study:

• To investigate the correlation between onion-bulb (OB) patterns and the classification of neuropathies as acquired or inherited.
• To determine if OB morphology can predict the underlying cause of demyelinating polyneuropathy.

Main Methods:

• Analysis of 131 nerve biopsy samples rich in onion-bulbs (OBs).
• Grading of OB patterns (generalized, mixed, focal) and inflammation by pathologists blinded to clinical history.
• Classification of neuropathies into inherited (n=49) or acquired (n=82) based on clinical data.

Main Results:

• Generalized OB patterns were significantly more common in inherited neuropathies (34/49) compared to acquired (17/82) (P<0.001).
• Mixed OB patterns were predominantly found in acquired neuropathies (48/82) versus inherited (6/49) (P<0.001).
• Inflammation was more frequent in acquired neuropathies (54/82) than inherited (14/49) (P=0.004).

Conclusions:

• Generalized onion-bulb patterns are associated with inherited demyelinating neuropathies.
• Mixed onion-bulb patterns are indicative of acquired demyelinating neuropathies.
• OB patterns reflect the distribution of Schwann cell involvement and correlate with electrophysiological findings in different neuropathy types.