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

Stendel R, Jahnke U, Straschill M - J Brachial Plex Peripher Nerve Inj (2006)

Bottom Line: Surprisingly 16 of the 29 patients (55.2%) showed a reduction or elimination of N35, P45 and N60.With paired stimulation a suppression of the amplitude of N20, P25 and P45 (p < 0.05; sign test), and a marked increment of N35 (p < 0.05; sign test) and N60 (not significant; sign test) of the second response could be observed.The results of the present investigation do not provide evidence of collateral innervation of peripherally denervated cortical neurons by neurons of adjacent cortical representation areas.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurosurgery, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany. ruediger.stendel@charite.de

ABSTRACT

Background: Animal studies have demonstrated complex cortical reorganization following peripheral nerve lesion. Central projection fields of intact nerves supplying skin areas which border denervated skin, extended into the deafferentiated cortical representation area. As a consequence of nerve lesions and subsequent reorganization an increase of the somatosensory evoked potentials (SEPs) was observed in cats when intact neighbouring nerves were stimulated. An increase of SEP-components of patients with nerve lesions may indicate a similar process of posttraumatic plastic cortical reorganization.

Methods: To test if a similar process of post-traumatic plastic cortical reorganization does occur in humans, the SEP of intact neighbouring hand nerves were recorded in 29 patients with hand nerve lesions. To hypothetically explain the observed changes of SEP-components, SEP recording following paired stimulation of the median nerve was performed in 12 healthy subjects.

Results: Surprisingly 16 of the 29 patients (55.2%) showed a reduction or elimination of N35, P45 and N60. Patients with lesions of two nerves showed more SEP-changes than patients with a single nerve lesion (85.7%; 6/7 nerves; vs. 34.2%; 13/38 nerves; Fisher's exact test, p < 0.05). With paired stimulation a suppression of the amplitude of N20, P25 and P45 (p < 0.05; sign test), and a marked increment of N35 (p < 0.05; sign test) and N60 (not significant; sign test) of the second response could be observed.

Conclusion: The results of the present investigation do not provide evidence of collateral innervation of peripherally denervated cortical neurons by neurons of adjacent cortical representation areas. They rather suggest that secondary components of the excitatory response to nerve stimulation are lost in cortical areas, which surround the denervated region.

No MeSH data available.


Related in: MedlinePlus

Changes of medium-latency SEP-components following nerve lesion. Changes of secondary SEP-components following complete right radial nerve lesion. Primary components (N20, P25) remain unaffected, while N35, P45 and N60 are depressed or abolished, when the intact directly neighbouring hand nerve is stimulated.
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Figure 1: Changes of medium-latency SEP-components following nerve lesion. Changes of secondary SEP-components following complete right radial nerve lesion. Primary components (N20, P25) remain unaffected, while N35, P45 and N60 are depressed or abolished, when the intact directly neighbouring hand nerve is stimulated.

Mentions: The primary SEP-components (N20, P25) of intact hand nerves remained unaffected by lesions of the neighbouring nerves. However, the amplitudes of the secondary, medium-latency components N35, P45 and N60 were markedly reduced or absent in 16 out of 29 patients (55.2%) or in 19 out of 45 nerves (42.2%) studied, whereas no significant differences of latencies could be found (Fisher's exact test, p > 0.05; Table 1). This amplitude change occurred only in those SEP, which were evoked from nerves with supply areas bordering directly the anaesthetic area (Figure 1).


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

Stendel R, Jahnke U, Straschill M - J Brachial Plex Peripher Nerve Inj (2006)

Changes of medium-latency SEP-components following nerve lesion. Changes of secondary SEP-components following complete right radial nerve lesion. Primary components (N20, P25) remain unaffected, while N35, P45 and N60 are depressed or abolished, when the intact directly neighbouring hand nerve is stimulated.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1636633&req=5

Figure 1: Changes of medium-latency SEP-components following nerve lesion. Changes of secondary SEP-components following complete right radial nerve lesion. Primary components (N20, P25) remain unaffected, while N35, P45 and N60 are depressed or abolished, when the intact directly neighbouring hand nerve is stimulated.
Mentions: The primary SEP-components (N20, P25) of intact hand nerves remained unaffected by lesions of the neighbouring nerves. However, the amplitudes of the secondary, medium-latency components N35, P45 and N60 were markedly reduced or absent in 16 out of 29 patients (55.2%) or in 19 out of 45 nerves (42.2%) studied, whereas no significant differences of latencies could be found (Fisher's exact test, p > 0.05; Table 1). This amplitude change occurred only in those SEP, which were evoked from nerves with supply areas bordering directly the anaesthetic area (Figure 1).

Bottom Line: Surprisingly 16 of the 29 patients (55.2%) showed a reduction or elimination of N35, P45 and N60.With paired stimulation a suppression of the amplitude of N20, P25 and P45 (p < 0.05; sign test), and a marked increment of N35 (p < 0.05; sign test) and N60 (not significant; sign test) of the second response could be observed.The results of the present investigation do not provide evidence of collateral innervation of peripherally denervated cortical neurons by neurons of adjacent cortical representation areas.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Neurosurgery, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany. ruediger.stendel@charite.de

ABSTRACT

Background: Animal studies have demonstrated complex cortical reorganization following peripheral nerve lesion. Central projection fields of intact nerves supplying skin areas which border denervated skin, extended into the deafferentiated cortical representation area. As a consequence of nerve lesions and subsequent reorganization an increase of the somatosensory evoked potentials (SEPs) was observed in cats when intact neighbouring nerves were stimulated. An increase of SEP-components of patients with nerve lesions may indicate a similar process of posttraumatic plastic cortical reorganization.

Methods: To test if a similar process of post-traumatic plastic cortical reorganization does occur in humans, the SEP of intact neighbouring hand nerves were recorded in 29 patients with hand nerve lesions. To hypothetically explain the observed changes of SEP-components, SEP recording following paired stimulation of the median nerve was performed in 12 healthy subjects.

Results: Surprisingly 16 of the 29 patients (55.2%) showed a reduction or elimination of N35, P45 and N60. Patients with lesions of two nerves showed more SEP-changes than patients with a single nerve lesion (85.7%; 6/7 nerves; vs. 34.2%; 13/38 nerves; Fisher's exact test, p < 0.05). With paired stimulation a suppression of the amplitude of N20, P25 and P45 (p < 0.05; sign test), and a marked increment of N35 (p < 0.05; sign test) and N60 (not significant; sign test) of the second response could be observed.

Conclusion: The results of the present investigation do not provide evidence of collateral innervation of peripherally denervated cortical neurons by neurons of adjacent cortical representation areas. They rather suggest that secondary components of the excitatory response to nerve stimulation are lost in cortical areas, which surround the denervated region.

No MeSH data available.


Related in: MedlinePlus