Pavel Haninec

Undulating course of nerve fibres and bands of Fontana in peripheral nerves of the rat

SummaryThe undulating course of nerve fibres and the optical effect of that course, i.e. the bands of Fontana, were studied in the peripheral nerves of the adult rat using light microscopy. The arrangement of collagen fibres in the endoneurium of these nerves was evaluated using transmission and scanning electron microscopy. No nerve fibres undulation was noted on the intracranial sections of the cranial nerves or on the spinal roots. In their endoneurium a few, irregularly arranged collagen fibrils were found. In contrast, the nerve fibres undulation and Fontanas bands were a constant feature in the peripheral course of the nerve trunks. They were discernible in vivo and on excised unfixed as well as fixed nerves. The nerve fibres follow a sine-curve course of variable frequence and amplitude. Exposed in vivo, the nerve fibres retained their wave-like course even after removal of the epineurium and perineurium. The endoneurium of these nerves contained numerous undulating longitudinally oriented bundles of collagen fibrils. These findings suggest that the undulating course of the nerve fibres in peripheral nerves is conditional upon the quantity and arrangement of their endoneurial collagen fibrils. When the nerve was stretched in the course of movement, the undulation became straightened out until it disappeared. Conversely, nerve shortening enhanced the undulation. Thus the wave-like alignment of the nerve fibres represents a physiological reserve length for nerve stretching.

Morphological evidence of collateral sprouting of intact afferent and motor axons of the rat ulnar nerve demonstrated by one type of tracer molecule

In our experimental paradigm we sutured the distal stump of a transected musculocutaneous nerve to an intact ulnar nerve of the rat in an end-to-side fashion. We demonstrated the formation of collateral sprouts from intact afferent and motor axons by application of one type of molecule conjugated by two different fluorophores (Fluoro-Ruby and Fluoro-Emerald). Fluoro-Ruby and Fluoro-Emerald were applied distal to end-to-side suture into fresh cut ends of the ulnar and musculocutaneous nerves, respectively. Formation of collateral sprouts was evidenced by findings of mixed (a yellow to orange color) fluorescence labeling of spinal motoneurons and dorsal root ganglia neurons. Colocalization of two different tracers retrogradely transported to the neurons was verified by the individual green and red fluorescence profiles analyzed by means of the computer-assisted image-analyzing system. Our results unequivocally demonstrate that a nerve stump attached to an intact nerve can induce collateral sprouting of both afferent and motor axons.

Non-specific cholinesterase activity of the developing peripheral nerves and its possible function in cells in intimate contact with growing axons of chick embryo

The results presented here demonstrate non‐specific cholinesterase (nChE) activity in the developing peripheral nerves of chick embryos at stages 25–26 according to Hamburger and Hamilton (1951, J. Morphol. 88, 49–92). Under the light microscope the use of simultaneous staining for nChE activity and silver proteinate impregnation revealed the axons to be surrounded by cells exhibiting nChE activity in the main nerve trunks and in the growing tips of nerves. Nerve branches arising from the main nerve trunks contained cells with positive reaction for nChE activity, too. Electron‐dense particles of the reaction product indicating nChE activity were found in the rough endoplasmic reticulum and in the perinuclear envelope of cells in close contact with growing nerve fibers and their growth cones. The same distribution of nChE activity was found in cells which were located near to nerve fasciculi but without direct contact with axons. Surprisingly, the cells in close contact with axons and their growth cones exhibited the end product of nChE activity in the outer part of their plasma membrane. The cells enveloping axons within the nerve trunks were apparently Schwann cells, while those around the growth cones at nerve tips could be identified as Schwann cells and/or mesenchymal cells of the hindlimb. The nChE reaction product was also detected in the axolemma of nerve fibers and their growth cones. The distribution of nChE activity in the developing peripheral nerves of chick embryos suggests that these molecules may influence the process of axonal elongation and locomotion. Several possible mechanisms of nChE action on growing axons can be presumed: (i) intracellular Ca2+ level regulation; (ii) providing an adhesive substrate; (iii) butyrate production affecting the cell metabolism and the distribution of neurotubules and neurofilaments. It is also assumed that nChE molecules are involved in the interactions of nerve fibers with Schwann cells and/or mesenchymal cells as well as in interneuronal interactions.

Morphometric analysis of early regeneration of motor axons through motor and cutaneous nerve grafts.

Peripheral nerve damage is a frequent consequence of trauma, tumor surgery or diseases. Clinical results of functional reinnervation after the application of cutaneous grafts are still unsatisfactory. Differences in the extracellular matrix are considered to be one of the factors responsible for poor results of motor axon reinnervation through the cutaneous graft. To verify these differences, we compared morphological features of the motor axons regenerating through the graft prepared from the saphenous nerve and the motor branch of the femoral nerve. Eighteen female adult rats (Wistar) were used in experiments. The saphenous nerve, the femoral nerve, and its main motor branch were exposed under deep anesthesia with ketamine and xylazine. The nerve graft (10 mm) prepared from the saphenous nerve was applied between the stumps of the transected motor branch of the femoral nerve in the 6 rats. In the next 6 rats, the nerve graft (10 mm) harvested from the motor branch of the femoral nerve was inserted between stumps of the transected motor branch of the femoral nerve on the contralateral side. All rats were perfused with Zambonis fixative solution 14 days after grafting. The samples of grafts and the intact motor branch (n = 6) were dissected and embedded in Durcupan ACM. Semithin sections stained with Toluidine Blue were used for morphometric analysis of myelinated axons by means of computer-assisted image analysis system. Ultrathin sections counterstained with uranyl acetate were viewed and photographed in an electron microscope. The number of myelinated motor axons showing early regeneration under conditions of the cutaneous and motor nerve grafts was similar. The diameter of axons and thickness of their myelin sheaths were significantly smaller when the axons regenerated into the saphenous nerve in contrast to the motor graft. Morphometric analysis of early regeneration of myelinated motor axons suggests that the cutaneous and motor branches of the femoral nerve provide different conditions not for the growth but for the maturation of motor axons.

Reinnervation of the rat musculocutaneous nerve stump after its direct reconnection with the C5 spinal cord segment by the nerve graft following avulsion of the ventral spinal roots: a comparison of intrathecal administration of brain-derived neurotrophic factor and Cerebrolysin

Experimental model based on the C5 ventral root avulsion was used to evaluate the efficacy of brain-derived neurotrophic factor (BDNF) and Cerebrolysin treatment on motor neuron maintenance and survival resulted in the functional reinnervation of the nerve stump. In contrast to vehicle, BDNF treatment reduced the loss and atrophy of motor neurons and enhanced the regrowth axon sprouts into the distal stump of musculocutaneous nerve. However, the axon diameter of the myelinated fibers was smaller than those of control rats. The morphometric results were related to a low score in behavioral test similar to vehicle-treated rats. Cerebrolysin treatment greatly protected the motor neurons against cell death. Moreover, morphometric features of myelinated axons were better than those of rats treated with vehicle or BDNF. The mean score of grooming test suggested better results of the functional motor reinnervation than after BDNF administration. The majority of rescued motor neurons regenerating their axons through nerve graft in both BDNF- and Cerebrolysin-treated rats expressed choline acetyltransferase immunostaining. The results demonstrate that BDNF has more modest effects in preventing the death of motor neurons and functional recovery of injured motor nerve after root avulsion than Cerebrolysin.

Dorsal root entry zone (DREZ) localization using direct spinal cord stimulation can improve results of the DREZ thermocoagulation procedure for intractable pain relief.

&NA; The dorsal root entry zone (DREZ) thermocoagulation for intractable pain after brachial plexus avulsion was performed in 21 patients. Good results in pain relief (relief of more than 75% of preoperative pain) were achieved in 62% of patients, whereby fair results (relief of 25–75% of preoperative pain) in 38% of patients. There was no patient with poor result (relief of less than 25% of preoperative pain). Complication rate was 14%. The whole patient population was subdivided into two groups (Group 1 and Group 2). Direct spinal cord bipolar stimulation and registration with the goal to localize DREZ was performed in the Group 2 consisting of 12 patients (n=12). The point on the spinal cord surface where no response after stimulus of low intensity was obtained was the site (the posterolateral sulcus) we identified as the most suitable point for the placement of radiofrequency thermocoagulation electrode. Comparing with the Group 1 consisting of nine patients (n=9), where the localization of DREZ by evoked potentials was not performed, significantly better effect of pain relief was recorded (P<0.05, odds ratio 10). There was no statistically significant difference (P>0.7) in complication rate in Group 1 and Group 2. Described electrophysiological technique is very helpful in identifying of DREZ and, in combination with microsurgical technique, can create DREZ thermocoagulation more effective.

Development and clinical significance of the musculus dorsoepitrochlearis in men

Musculus dorsoepitrochlearis is a typical muscle variation, which, if in full extent, is represented by the muscular or fibromuscular slip detached from the anteroinferior border of the musculus latissimus dorsi. It passes over the axilla under the axillary fascia crossing the medial side of the brachial plexus and continues as a septum intermusculare mediale brachii distally to the medial epicondyle of humerus. Its full extent is rarely developed—the connection into the intermuscular septum being mostly absent. Muscular slips from the musculus latissimus then insert on various structures in the axilla, often on the crest of greater tubercle of humerus or into the musculus pectoralis major (this variation is known as the axillary arch of Langer) or to other neighboring structures (coracoid process, fasciae of muscles). In our observations, 209 patients with traumatic lesions of the brachial plexus underwent surgical procedure. The presence of the musculus dorsoepitrochlearis has been observed. It was found in the form of various slips from the musculus latissimus dorsi in 4 patients. In 3 of those 4 patients, the innervation was derived from the nervus thoracodorsalis. We also presented 2 case reports of patients with clinical symptoms caused by compression of nerves in the axilla by the dorsoepitrochlear strip. Clin. Anat. 22:481–488, 2009.

Rescue of rat spinal motoneurons from avulsion-induced cell death by intrathecal administration of IGF-I and Cerebrolysin.

Ventral root avulsion results in the loss of motoneurons in the corresponding spinal cord segment. In the present experiments we have tested effects of insulin-like growth factor-I (IGF-I) and Cerebrolysin on survival of avulsed motoneurons after their chronic intrathecal administration in the adult rats. We have found that avulsion of the C5 ventral roots results in significant loss of motoneurons in the same spinal cord segment due mainly to apoptosis. In comparison to the untreated control rats, the amount of motoneuron survival in avulsed ventral horn was significantly higher after 4 weeks intrathecal administration of IGF-I or Cerebrolysin. No significant differences were observed between effects of IGF-I and Cerebrolysin in our experimental model. The results suggest that both IGF-I and Cerebrolysin can reduce avulsion-induced loss of adult rat motoneurons.

Types and severity of operated supraclavicular brachial plexus injuries caused by traffic accidents

BackgroundBrachial plexus injuries occur in up to 5% of polytrauma cases involving motorcycle accidents and in approximately 4% of severe winter sports injuries. One of the criteria for a successful operative therapy is the type of lesion. Upper plexus palsy has the best prognosis, whereas lower plexus palsy is surgically untreatable. The aim of this study was to evaluate a group of patients with brachial plexus injury caused by traffic accidents, categorize the injuries according to type of accident, and look for correlations between type of palsy (injury) and specific accidents.MethodsA total of 441 brachial plexus reconstruction patients from our department were evaluated retrospectively (1993 to 2011). Sex, age, neurological status, and the type and cause of injury were recorded for each case. Patients with BPI caused by a traffic accident were assessed in detail.ResultsTraffic accidents were the cause of brachial plexus injury in most cases (80.7%). The most common type of injury was avulsion of upper root(s) (45.7%) followed by rupture (28.2%), complete avulsion (16.9%) and avulsion of lower root(s) (9.2%). Of the patients, 73.9% had an upper, 22.7% had a complete and only 3.4% had a lower brachial plexus palsy. The main cause was motorcycle accidents (63.2%) followed by car accidents (23.5%), bicycle accidents (10.7%) and pedestrian collisions (3.1%) (p < 0.001). Patients involved in car accidents had a higher percentage of lower avulsion (22.7%) and a lower percentage of upper avulsion (29.3%), whereas cyclists had a higher percentage of upper avulsion (68.6%) based on the data from the entire group of patients (p < 0.001). Lower plexus palsy was significantly increased in patients after car accidents (9.3%, p < 0.05). In the two main groups (car and motorcycle accidents), significantly more upper and fewer lower palsies were present. In the bicycle accident group, upper palsy was the most common (89%).ConclusionStudy results indicate that the most common injury was an upper plexus palsy. It was characteristic of bicycle accidents, and significantly more common in car and motorcycle accidents. The results also indicate that it is important to consider the potential of a brachial plexus injury after serious traffic accidents and to examine both upper extremities in detail even if some motor function is preserved.

Localization of dipeptidylpeptidase IV and alkaline phosphatase in developing spinal cord meninges and peripheral nerve coverings of the rat

Localization of dipeptidylpeptidase IV was studied in the spinal cord meninges and peripheral nerve coverings of fetal and postnatal rats. In the same sections, the localization of alkaline phosphatase was monitored.