Changes of medium-latency SEP-components following peripheral nerve lesion

Area of Science:

• Neuroscience
• Somatosensory System
• Cortical Plasticity

Background:

• Animal studies show cortical reorganization after peripheral nerve lesions, with adjacent nerve fields expanding into denervated areas.
• This reorganization in cats led to increased somatosensory evoked potentials (SEPs) when intact neighboring nerves were stimulated.

Purpose of the Study:

• To investigate if similar post-traumatic plastic cortical reorganization occurs in humans following nerve lesions.
• To record SEPs from intact neighboring hand nerves in patients with nerve lesions.

Main Methods:

• Somatosensory evoked potentials (SEPs) were recorded from intact neighboring hand nerves in 29 patients with hand nerve lesions.
• Paired median nerve stimulation was used in 12 healthy subjects to explore SEP changes.

Main Results:

• 55.2% of patients showed reduced or eliminated N35, P45, and N60 SEP components.
• Patients with double nerve lesions exhibited more SEP changes than those with single lesions (85.7% vs. 34.2%).
• Paired stimulation in healthy subjects revealed suppressed N20, P25, and P45 amplitudes and increased N35 and N60 responses.

Conclusions:

• The study found no evidence of collateral innervation in humans as suggested by animal models.
• Results indicate a loss of secondary SEP components in cortical areas surrounding denervated regions in humans.