New on PubMed:

Investigation of the regeneration potential of the recurrent laryngeal nerve (RLN) after compression injury, using neuromonitoring.

Moskalenko V, Hüller M, Gasser M, Demidchik Y, Thiede A, Timm S, Ulrichs K, Hamelmann W.

Department of General and Visceral Surgery, Hospital of the Johannes Gutenberg-University Mainz, Langenbeckstr. 1, D-55131, Mainz, Germany. moskalenko@tut.by

INTRODUCTION:

The aim of this study was to investigate the regeneration potential of RLN after the compression of the nerve, without disrupting its continuity, using neuromonitoring.

METHODS: In the first operation, the RLN and nervus vagus of adult Goettingen minipigs were dissected free, and the neuromonitoring parameters (amplitude, threshold and lag time of signal) were measured. Injury of the RLN was induced using a "bulldog" clamp. When the signal was no longer detectable, after the 15 min regeneration phase, the operation was finished. The neuromonitoring studies (see above) were repeated in a second operation 6 months later. RESULTS: (1) After the first operation, acute clamping of the RLN led to a reduction in the amplitude of the neuromonitoring signal; the lag time and the threshold of signal remained. Complete restitution of the signal was observed during the first regeneration phase. Repeated clamping led to complete disappearance of the signal. (2) During the second operation, i.e., after 6 months of regeneration, the neuromonitoring signals of both RLN and nervus vagus were detected in 93% of the GMP. No statistical differences (p = 0.17) were noticed between the amplitude of the RLN before the nerve injury (first operation) and after nerve regeneration (second operation). A significant increase in the lag time (p <>

PMID: 18751999 [PubMed - indexed for MEDLINE]

Regeneration: Sensory vs Motor nerves?

Comparison of the fastest regenerating motor and sensory myelinated axons in the same peripheral nerve
Mihai Moldovan1, Jesper Sørensen1,2 and Christian Krarup1,

Brain 2006 129(9):2471-2483; doi:10.1093/brain/awl184

Functional outcome after peripheral nerve regeneration is often poor, particularly involving nerve injuries far from their targets. Comparison of sensory and motor axon regeneration before target reinnervation is not possible in the clinical setting, and previous experimental studies addressing the question of differences in growth rates of different nerve fibre populations led to conflicting results. We developed an animal model to compare growth and maturation of the fastest growing sensory and motor fibres within the same mixed nerve after Wallerian degeneration. Regeneration of cat tibial nerve after crush (n = 13) and section (n = 7) was monitored for up to 140 days, using implanted cuff electrodes placed around the sciatic and tibial nerves and wire electrodes at plantar muscles. To distinguish between sensory and motor fibres, recordings were carried out from L6–S2 spinal roots using cuff electrodes. The timing of laminectomy was based on the presence of regenerating fibres along the nerve within the tibial cuff. Stimulation of unlesioned tibial nerves (n = 6) evoked the largest motor response in S1 ventral root and the largest sensory response in L7 dorsal root. Growth rates were compared by mapping the regenerating nerve fibres within the tibial nerve cuff to all ventral or dorsal roots and, regardless of the lesion type, the fastest growth was similar in sensory and motor fibres.