Number Of Motor Fibers Research Articles

Preconditions for the Successful Segmental Step-Wise Reconstruction of the Global Function of the Upper Extremity in Case of the Complete Brachial Plexus Injury (Case Report)

Background. The prognosis of recovery of the distal muscles (dM) of the upper extremity (UE) in complete brachial plexus injuries (cBPI) after any selective nerve transfer (NT) is poor. Free functioning muscle transfer (FFMT) is deprived of the disadvantages of NT. By combining NT and FFMT one can achieve recovery of the global functionality of UE in cBPI.
 Objective: to define theoretical and clinical preconditions for each stage (S) of the segmental reconstruction of UE in cBPI.
 Materials and Methods. 38 years old male patient 3 months after cBPI underwent NT (S1) of the phrenic to musculocutaneous nerve; branches of the spinal accessory nerve were transferred to axillary and suprascapular nerves. 36 months after S1 the patient underwent wrist (WA) and trapeziometacarpal arthrodesis (TMCA) (S2). 43 months after S1 the patient underwent FFMT of the gracilis muscle (S3). Clinical and neurological, electroneuromyographic (EMG), and X-ray examinations were carried out within the expected time to achieve the expected result after the corresponding stages of reconstruction. Results. 26 months after S1 m. biceps brachii and m. deltoideus recovered to M4; m. supra-infraspinatus ineffectively recovered to M3. A stable arthrodesis effect in WA and TMCA was achieved after 42 months in general. Poor clinical and EMG recovery of the gracilis muscle (S3) within the expected time led to indefinite postponement of S4, with clinical and EMG control every 3 months.
 Conclusions. Clinical signs of functional recovery cannot be a prerequisite for using a primary recipient nerve as a secondary donor nerve; the number of motor fibers in the donor nerve must be confirmed by objective data of morphometric and histochemical express methods; theoretical preconditions of the “sitting donor” technique appear to be the most promising in terms of recovery of dM of UE.

A nerve too far?

The neurotisation of peripheral nerves following avulsion brachial plexus injuries has given hope for patients with a condition which used to be incurable. The use of ipsilateral extraplexus nerve transfer is limited by the number of motor fibres that are available. The idea of transferring the

Partial Recovery of Respiratory Function and Diaphragm Reinnervation following Unilateral Vagus Nerve to Phrenic Nerve Anastomosis in Rabbits

Respiratory dysfunction is the leading cause of mortality following upper cervical spinal cord injury (SCI). Reinnervation of the paralyzed diaphragm via an anastomosis between phrenic nerve and a donor nerve is a potential strategy to mitigate ventilatory deficits. In this study, anastomosis of vagus nerve (VN) to phrenic nerve (PN) in rabbits was performed to assess the potential capacity of the VN to compensate for lost PN inputs. At first, we compared spontaneous discharge pattern, nerve thickness and number of motor fibers between these nerves. The PN exhibited a highly rhythmic discharge while the VN exhibited a variable frequency discharge pattern. The rabbit VN had fewer motor axons (105.3±12.1 vs. 268.1±15.4). Nerve conduction and respiratory function were measured 20 weeks after left PN transection with or without left VN-PN anastomosis. Compared to rabbits subjected to unilateral phrenicotomy without VN-PN anastomosis, diaphragm muscle action potential (AP) amplitude was improved by 292%, distal latency by 695%, peak inspiratory flow (PIF) by 22.6%, peak expiratory flow (PRF) by 36.4%, and tidal volume by 21.8% in the anastomosis group. However, PIF recovery was only 28.0%, PEF 28.2%, and tidal volume 31.2% of Control. Our results suggested that VN-PN anastomosis is a promising therapeutic strategy for partial restoration of diaphragm reinnervation, but further modification and improvements are necessary to realize the full potential of this technique.

Anatomical feasibility of vagus nerve esophageal branch transfer to the phrenic nerve.

This study measured the vagus and phrenic nerves from 12 adult cadavers. We found that the width and thickness of the vagus and phrenic nerves were different in the chest. The distance from the point of the vagus nerve and phrenic nerve on the plane of the inferior border of portal pulmonary arteries (T point) was approximately 7 cm to the diaphragm and was approximately 10 cm to the clavicle level. The number of motor fibers in the vagus nerves was 1 716 ± 362, and the number of nerve fibers was 4 473 ± 653. The number of motor fibers in the phrenic nerves ranged from 3 078 ± 684 to 4 794 ± 638, and the number of nerve fibers ranged from 3 437 ± 642 to 5 071 ± 723. No significant difference was found in the total number of nerve fibers. The results suggest that width, thickness, and total number of nerve fibers are similar between the vagus and phrenic nerves, but the number of motor fibers is different between them.

Variation in nerve autograft length increases fibre misdirection and decreases pruning effectiveness. An experimental study in the rat median nerve

Objectives: In the clinical set, autologus nerve grafts are the current option for reconstruction of nerve tissue losses. The length of the nerve graft has been suggested to affect outcomes. Experiments were performed in the rat in order to test this assumption and to detect a possible mechanism to explain differences in recovery.Methods: The rat median nerve was repaired by ulnar nerve grafts of different lengths. Rats were evaluated for 12 months by behavioural assessment and histological studies, including ATPase myofibrillary histochemistry and retrograde neuronal labelling.Results: It was demonstrated that graft length interferes in behavioural functional recovery that here correlates to muscle weight recovery. Short nerve grafts recovered faster and better. Reinnervation was not specific either at the trunk level or in the muscle itself. The normal mosaic pattern of Type I muscle fibres was never restored and their number remained largely augmented. An increment in the number of motor fibres was observed after the nerve grafting in a predominantly sensory branch in all groups. This increment was more pronounced in the long graft group. In the postoperative period, about a 20% reduction in the number of misdirected motor fibres occurred in the short nerve graft group only.Conclusion: Variation in the length of nerve grafts interferes in behavioural recovery and increases motor fibres misdirection. Early recovery onset was related to a better outcome, which occurs in the short graft group.

Neural asymmetry in male fiddler crabs

In adult male fiddler crabs, Uca pugnax, there is a marked enlargement of the 1st thoracic ganglion and its nerve root on the side of the major cheliped compared to the side of the minor cheliped. Retrograde uptake of cobalt via the cut ends of the motoneurons revealed a significant hypertrophy of their somata and dendritic fields on the major side of the ganglion compared to the minor side in the male fiddler crabs. (In female fiddler crabs which have two minor chelipeds the motoneurons were similar in size on both sides of the ganglion.) Since the number and distribution of motoneuron somata was relatively constant in the two halves of each ganglion, homologies for individual or groups of neurons could be recognized. The number of axon profiles in a cross-sectional montage of the entire nerve root of the major side in a male fiddler crab was several times greater than that of the minor side in random samples which were appropriately scaled in area. In samples of equal areas the axonal density was similar on the major and minor sides, as was also the range of axon diameters; both signify no difference in size of axons between the contralateral nerve roots. Consequently enlargement of the nerve root on the major side is due to a relative increase in the number of axons. This increase is in sensory fibers since the number of motor fibers are bilaterally constant. Thus neural asymmetry in male fiddler crabs involves hypertrophy of the motoneurons and hyperplasia of the sensory neurons associated with the enlarged condition of the major cheliped.

Study of motor units and arrangement of myons of human musculus plantaris.

It was seen in ten specimens that their plantaris muscle had different sizes of myons, whicnother were found. The number of motor units of the plantaris was counted in five subjects after transverse section of the muscle and nervous fibers of each of them. Considering the number of motor fibers as 60% in each nerve, the average value of muscle fibers per motor unit was 372, which is quit a small number. The fact led us to think that the plantaris muscle has a very refined function.