We studied electrophysiological and morphological properties of the Aα- and Aβ-fibers in the regenerating sciatic nerve to establish whether these fiber types regenerate in numerical proportion and ...whether and how the electrophysiological properties of these fiber types are adjusted during regeneration.
Compound action potentials were evoked from isolated sciatic nerves 12 weeks after autografting. Nerve fibers were gradually recruited either by increasing the stimulus voltage from subthreshold to supramaximal levels or by increasing the interval between two supramaximal stimuli to obtain the cumulative distribution of the extracellular firing thresholds and refractory periods, respectively. Thus, the mean conduction velocity (MCV), the maximal charge displaced during the compound action potential (
Q
max), the mean firing threshold (
V
50), and the mean refractory period (
t
50) were determined. The number of myelinated nerve fibers and their fiber diameter frequency distributions were determined in the peroneal nerve.
Mathematical modeling applied to fiber recruitment and diameter distributions allowed discrimination of the Aα- and Aβ-fiber populations. In regenerating nerves, the number of Aα-fibers increased fourfold while the number of Aβ-fibers did not change. In regenerating Aα- and Aβ-fibers, the fiber diameter decreased and
V
50 and
t
50 increased. The regenerating Aα-fibers' contribution to
Q
max decreased considerably while that of the Aβ-fibers remained the same. Correlation of the electrophysiological data to the morphological data provided indications that the ion channel composition of both the Aα- and Aβ-fibers are altered during regeneration. This demonstrates that combining morphometric and electrophysiological analysis provides better insight in the changes that occur during regeneration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Spinal nerve root avulsions frequently occur in brachial plexus injuries caused by traction. Such lesions are considered to afflict the central nervous system (CNS) and are, therefore, believed to be ...beyond surgical repair. The present experimental study was initiated to challenge this hypothesis. The ventral rootlets of C-7 were avulsed from the spinal cord in 28 cats via an anterior approach and subsequently reimplanted into the cord at the site of origin. In nonoperated control cats and cats undergoing reimplantation, electrophysiological experiments were performed and horseradish peroxidase was administered to the spinal nerve on the reimplanted side after survival times ranging from 6 to 293 days. Spinal cord sections in all cats were stained for neurofilament, acetylcholinesterase (AChE), Nissl, and glial fibrillary acidic protein. Horseradish peroxidase-labeled ventral horn motoneurons were found as early as 14 days after reimplantation and their number increased with time. On Days 209 and 293, the number of labeled neurons equaled the number of labeled ventral horn neurons in the two control cats that did not undergo surgery. Starting on Day 6 after reimplantation, the appearance of the ventral horn and the white matter in the neurofilament, AChE, and Nissl-stained sections changed as a result of the CNS response to the injury. A return to their normal appearance could be observed in these stainings from Day 209 onward. Glial fibrillary acidic protein-positive astrocytic tissue was consistently found in the ventral horn and in the white matter reimplantation area. From Day 69 onward, electrophysiological stimulation of the spinal nerve C-7 on the reimplanted side elicited an electromyogram response in the spinodeltoid muscle. The latency and threshold intensity of the C-7 responses were initially increased but equalized to match the nonoperated controls between 98 and 122 days after reimplantation. The results of this study show that functional regeneration of ventral horn neurons after root avulsion and subsequent reimplantation in the cat is possible.
This study focuses on the capacity of motor axons to elongate from the spinal cord through an autologous nerve graft into a spinal nerve. Applying a ventral surgical approach, C7 ventral roots were ...avulsed from the cord in 12 cats. Autologous saphenous nerve grafts were implanted into the cord at the ventral root outlet site and coaptated to the spinal nerve. Outgrowth of axons was studied at survival times 7, 14, 30, 60 and 120 days, respectively. The results showed horseradish peroxidase positive motoneurons in the C7 ventral horn after retrograde labeling, as well as neurofilament and acetylcholinesterase positive axons in the entire trajectory from spinal cord to spinal nerve. Neurotization of the C7 spinal nerve started between 14 and 30 days after graft implantation. In addition electrophysiology provided evidence that outgrowing axons had re‐established functional contact with the spinodeltoid muscle at 120 days after implantation.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
25.
Nerve root repair Thomeer, Ralph T W M; Malessy, Martijn J A; Marani, Enrico
Journal of neurosurgery
96, Issue:
1 Suppl
Journal Article
Traumatic root avulsions of the brachial plexus constitute a devastating lesion resulting in loss of function of the upper limb and carry a large emotional and socioeconomic impact. In this ...literature survey, the different factors involved in root avulsion are discussed in combination with various surgical techniques for repair of experimental ventral root avulsion. Until now repair of root avulsions did not generate unequivocal proof of recovery of limb function, particularly of the hand. More experimental studies are needed to assess the efficacy of several repair techniques, the optimal timing for surgery, and the complications associated with spinal cord manipulation.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Acromesomelic dysplasias are skeletal disorders that disproportionately affect the middle and distal segments of the appendicular skeleton. We report genetic mapping studies in four families with ...acromesomelic dysplasia Maroteaux type (AMDM), an autosomal recessive osteochondrodysplasia. A peak LOD score of 5.1 at recombination fraction 0 was obtained with fully informative markers on human chromosome 9. In three of the four families, the affected offspring are products of consanguineous marriages; if it is assumed that these affected offspring are homozygous by descent for the region containing the AMDM locus, a 6.9-cM AMDM candidate interval can be defined by markers D9S1853 and D9S1874. The mapping of the AMDM locus to human chromosome 9 indicates that AMDM is genetically distinct from the two other mapped acromesomelic dysplasias, Hunter-Thompson type and Grebe type, which are caused by mutations in CDMP1 on human chromosome 20.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Object The aim of this retrospective study was to evaluate the restoration of shoulder function by means of supra-scapular nerve neurotization in adult patients with proximal C-5 and C-6 lesions due ...to a severe brachial plexus traction injury (BPTI). The primary goal of brachial plexus reconstructive surgery was to restore the biceps muscle function and, secondarily, to reanimate shoulder function. Methods Suprascapular nerve neurotization was performed by grafting the C-5 nerve in 24 patients and by accessory or hypoglossal nerve transfer in 29 patients. Additional neurotization involving the axillary nerve could be performed in 18 patients. Postoperative needle electromyography studies of the supraspinatus, infraspinatus, and deltoid muscles showed signs of reinnervation in most patients; however, active glenohumeral shoulder function recovery was poor. In nine (17%) of 53 patients supraspinatus muscle strength was Medical Research Council (MRC) Grade 3 or 4 and in four (8%) infraspinatus muscle power was Grade 3 or 4. In 18 patients in whom deltoid muscle reinnervation was attempted, MRC Grade 3 or 4 function was demonstrated in two (11%). In the overall group, eight patients (15%) exhibited glenohumeral abduction with a mean of 44 ± 17° (standard deviation SD) (median 45°) and four patients (8%) exhibited glenohumeral exorotation with a mean of 48 ± 24° (SD) (median 53°). In only three patients (6%) were both functions regained. Conclusions The reanimation of shoulder function in patients with proximal C-5 and C-6 BPTIs following supra-scapular nerve neurotization is disappointingly low.
We studied electrophysiological and morphological properties of the Aalpha- and Abeta-fibers in the regenerating sciatic nerve to establish whether these fiber types regenerate in numerical ...proportion and whether and how the electrophysiological properties of these fiber types are adjusted during regeneration. Compound action potentials were evoked from isolated sciatic nerves 12 weeks after autografting. Nerve fibers were gradually recruited either by increasing the stimulus voltage from subthreshold to supramaximal levels or by increasing the interval between two supramaximal stimuli to obtain the cumulative distribution of the extracellular firing thresholds and refractory periods, respectively. Thus, the mean conduction velocity (MCV), the maximal charge displaced during the compound action potential (Q(max)), the mean firing threshold (V(50)), and the mean refractory period (t(50)) were determined. The number of myelinated nerve fibers and their fiber diameter frequency distributions were determined in the peroneal nerve. Mathematical modeling applied to fiber recruitment and diameter distributions allowed discrimination of the Aalpha- and Abeta-fiber populations. In regenerating nerves, the number of Aalpha-fibers increased fourfold while the number of Abeta-fibers did not change. In regenerating Aalpha- and Abeta-fibers, the fiber diameter decreased and V(50) and t(50) increased. The regenerating Aalpha-fibers' contribution to Q(max) decreased considerably while that of the Abeta-fibers remained the same. Correlation of the electrophysiological data to the morphological data provided indications that the ion channel composition of both the Aalpha- and Abeta-fibers are altered during regeneration. This demonstrates that combining morphometric and electrophysiological analysis provides better insight in the changes that occur during regeneration.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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