Chronic polyneuropathy of undetermined cause

Area of Science:

• Neurology
• Pathology

Background:

• Peripheral neuropathy diagnosis can be challenging, with a subset of patients remaining undiagnosed despite thorough investigation.
• Sural nerve biopsy is a key diagnostic tool for peripheral neuropathies.

Purpose of the Study:

• To determine the proportion of chronic polyneuropathy cases remaining undiagnosed after intensive investigation.
• To assess the long-term course and potential for diagnosis on re-examination of these patients.

Main Methods:

• Review of 519 patient case histories with sural nerve biopsies.
• Analysis of clinical features, cerebrospinal fluid (CSF) protein, nerve conduction studies, and biopsy findings.
• Re-examination of a subset of patients after a median of 3 years.

Main Results:

• In 13% of patients (67/519) with symmetrical polyneuropathy >1 year, the cause remained undiagnosed.
• Males were more commonly affected (3:1 ratio), with a mean age of onset of 50.6 years.
• Chronic axonal degeneration was the usual biopsy finding; most patients had mild disability and slow progression.
• Aetiological factors (e.g., malignancy, alcoholism) were identified in 36% of re-examined patients.

Conclusions:

• Intensive investigation successfully diagnoses most chronic polyneuropathies.
• A small percentage of chronic polyneuropathies remain undiagnosed, characterized by slow progression and mild disability.
• Continued follow-up and re-examination can establish a diagnosis in some previously undiagnosed cases.