Chronic inflammatory demyelinating polyradiculoneuropathy-associated tremor: Phenotype and pathogenesis

Area of Science:

• Neurology
• Neurophysiology
• Movement Disorders

Background:

• Tremor in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is frequently underrecognized.
• The underlying pathophysiology of CIDP-related tremor is not fully understood.

Purpose of the Study:

• To evaluate the characteristics of tremor in CIDP patients.
• To test the hypothesis that peripheral inputs affect central motor processing in CIDP tremor.
• To assess tremor variability in CIDP using the tremor stability index (TSI).

Main Methods:

• Prospective recruitment of 24 CIDP patients from neuromuscular clinics.
• Exclusion of alternative causes for neuropathy and tremor.
• Clinical assessment, surface electromyography (EMG), and accelerometry for tremor analysis.
• Correlation analysis between nerve conduction studies and tremor characteristics.

Main Results:

• 66% of CIDP patients exhibited mild upper limb postural and action tremor.
• Tremor spectral peaks varied across muscles, with higher frequencies in proximal muscles.
• Tremor correlated with ulnar nerve F-wave latency and median nerve sensory amplitude.
• The tremor stability index (TSI) was significantly higher in CIDP patients compared to essential tremor.

Conclusions:

• Postural tremor is a common manifestation in CIDP.
• CIDP tremor appears to have central generation but is influenced by peripheral nerve abnormalities.
• High beat-to-beat variability and frequency gradation suggest a complex pathophysiology for CIDP tremor.
• Findings may aid clinicians in diagnosing neuropathic tremor.