Prospective study on the Eustachian tube function during Frenzel maneuver in a hypobaric/hyperbaric pressure chamber.

INTRODUCTION: The Frenzel maneuver describes a technique for middle ear equalizing which is frequently used by apnea divers. It offers advantages compared to the most commonly used techniques such as the Valsalva or Toynbee maneuver. Until now, there is insufficient literature about the pressure dynamics and Eustachian tube (ET) function during the Frenzel maneuver. The aim of the present study was to characterize the ET function during the Frenzel maneuver. MATERIALS AND METHODS: By means of an established standardized profile of compression and decompression in a hypo/hyperbaric pressure chamber, we examined different parameters such as the ET opening pressure (ETOP), ET opening duration (ETOD), and ET opening frequency (ETOF) in 11 experienced apnea divers and compared them to the parameters during the Valsalva and Toynbee maneuver. RESULTS: Standard values for ETOP, ETOD, and ETOF could be established for the Frenzel maneuver under standardized conditions in a hypo/hyperbaric pressure chamber. Compared to the Frenzel maneuver, ETOP was higher and ETOD longer (both p < 0.001) during the Valsalva maneuver whereas ETOP was lower and ETOD shorter (both p < 0.001) during the Toynbee maneuver. No difference regarding ETOF was observed between the Frenzel, Valsalva, and Toynbee maneuver. DISCUSSION: The Frenzel maneuver was shown to be at least as effective as the Valsalva maneuver concerning ET opening. We believe that knowledge of the Frenzel technique might facilitate the pressure equalization during diving and recommend implementation of an appropriate equalization training in apnea and scuba diving education.

Long-term therapy with botulinum toxin in facial synkinesis: Retrospective data analysis of data from 1998 to 2018.

OBJECTIVES: Treatment with botulinum toxin A (BoNT) is the therapy of choice for many patients with facial synkinesis. Repeated injections relieve hypertonicity and hyperkinesis of reinnervated mimic muscles. Aim of the study was to prove if the injection regime and dosage of BoNT change during long-time therapy. DESIGN: Retrospective analysis of patients´ data, who were treated for synkinesis with BoNT from 1998 to 2018. SETTING: Tertiary referral facial nerve centre. PARTICIPANTS: Injection pattern of BoNT was based on clinical symptoms, observations of the specialist and on previous treatment pattern. Onabotulinumtoxin (OnaBoNT), Incobotulinumtoxin (IncoBoNT) and Abobotulinumtoxin (AboBoNT) were available for treatment. Patients consulted our department for following treatment as soon as the symptoms re-occurred. MAIN OUTCOME MEASURES: Change in dosage and injection pattern, the time intervals between treatments over the entire therapy period. RESULTS: Seventy-three patients were repeatedly injected. The median number of treatments was 18, the median treatment interval was 3.0 months. During the initial treatment, orbicularis oculi and the mentalis muscles were the most frequently injected muscles (94%). During repeated treatment, the number of injected muscles increased significantly (P < .0001), whereas the dose per muscle remained stable. The initial dose was 24 U (95%-CI 22-27 U) for OnaBoNT and IncoBoNT; 69 U for AboBoNT(95%-CI 44-94 U). We observed a significant increase in dosage for OnaBoNT and IncoBoNT (P < .0001) during the long-term therapy. The time intervals between treatments were stable for all three BoNT preparations (P > .05). CONCLUSIONS: We observed significant change in treatment dose and injection pattern of BoNT in patients with facial synkinesis. These results provide an orientation in dose finding and injection regimen of BoNT in the long-term course of therapy.

Motor, sensitive, and vegetative recovery in rats with compressive spinal-cord injury after combined treatment with erythropoietin and whole-body vibration.

BACKGROUND: Physical therapy with whole body vibration (WBV) following compressive spinal cord injury (SCI) in rats restores density of perisomatic synapses, improves body weight support and leads to a better bladder function. The purpose of the study was to determine whether the combined treatment with WBV plus erythropoietin (EPO) would further improve motor, sensory and vegetative functions after SCI in rats. METHODS: Severe compressive SCI at low thoracic level was followed by a single i.p. injection of 2,5µg (250 IU) human recombinant EPO. Physical therapy with WBV started on 14th day after injury and continued over a 12-week post injury period. Locomotor recovery, sensitivity tests and urinary bladder scores were analysed at 1, 3, 6, 9, and 12 weeks after SCI. The closing morphological measurements included lesion volume and numbers of axons in the preserved perilesional neural tissue bridges (PNTB). RESULTS: Assessment of motor performance sensitivity and bladder function revealed no significant effects of EPO when compared to the control treatments. EPO treatment neither reduced the lesion volume, nor increased the number of axons in PNTB. CONCLUSIONS: The combination of WBV + EPO exerts no positive effects on hind limbs motor performance and bladder function after compressive SCI in rats.

Facial Nerve Repair by Muscle-Vein Conduit in Rats: Functional Recovery and Muscle Reinnervation.

The facial nerve is the most frequently damaged nerve in head and neck traumata. Repair of interrupted nerves is generally reinforced by fine microsurgical techniques; nevertheless, regaining all functions is the exception rather than the rule. The so-called "postparalytic syndrome," which includes synkinesia and altered blink reflexes, follows nerve injury. The purpose of this study was to examine if nerve-gap repair using an autologous vein filled with skeletal muscle would improve axonal regeneration, reduce neuromuscular junction polyinnervation, and improve the recovery of whisking in rats with transected and sutured right buccal branches of the facial nerve. Vibrissal motor performance was studied with the use of a video motion analysis. Immunofluorescence was used to visualize and analyze target muscle reinnervation. The results taken together indicate a positive effect of muscle-vein-combined conduit (MVCC) on the improvement of the whisking function after reparation of the facial nerve in rats. The findings support the recent suggestion that a venal graft with implantation of a trophic source, such as autologous denervated skeletal muscle, may promote the monoinnervation degree and ameliorate coordinated function of the corresponding muscles.

Numbers of Axons in Spared Neural Tissue Bridges But Not Their Widths or Areas Correlate With Functional Recovery in Spinal Cord-Injured Rats.

The relationships between various parameters of tissue damage and subsequent functional recovery after spinal cord injury (SCI) are not well understood. Patients may regain micturition control and walking despite large postinjury medullar cavities. The objective of this study was to establish possible correlations between morphological findings and degree of functional recovery after spinal cord compression at vertebra Th8 in rats. Recovery of motor (Basso, Beattie, Bresnahan, foot-stepping angle, rump-height index, and ladder climbing), sensory (withdrawal latency), and bladder functions was analyzed at 1, 3, 6, 9, and 12 weeks post-SCI. Following perfusion fixation, spinal cord tissue encompassing the injury site was cut in longitudinal frontal sections. Lesion lengths, lesion volumes, and areas of perilesional neural tissue bridges were determined after staining with cresyl violet. The numbers of axons in these bridges were quantified after staining for class III ß-tubulin. We found that it was not the area of the spared tissue bridges, which is routinely determined by magnetic resonance imaging (MRI), but the numbers of axons in them that correlated with functional recovery after SCI (Spearman's ρ > 0.8; p < 0.001). We conclude that prognostic statements based only on MRI measurements should be considered with caution.

Neutralizing BDNF and FGF2 injection into denervated skeletal muscle improve recovery after nerve repair.

BACKGROUND: After facial nerve injury and surgical repair in rats, recovery of vibrissal whisking is associated with a high proportion of mono-innervated neuro-muscular junctions (NMJs). Our earlier work with Sprague Dawley (SD)/Royal College of Surgeons (RCS) rats, which are blind and spontaneously restore NMJ-monoinnervation and whisking, showed correlations between functional recovery and increase of fibroblast growth factor-2 (FGF2) and brain-derived neurotrophic factor (BDNF) in denervated vibrissal muscles. METHODS: We used normally sighted rats (Wistar), in which NMJ-polyinnervation is highly correlated with poor whisking recovery, and injected the vibrissal muscle levator labii superioris (LLS) with combinations of BDNF, anti-BDNF, and FGF2 at different postoperative periods after facial nerve injury. RESULTS: Rats receiving anti-BDNF+FGF2 showed low NMJ-polyinnervation and best recovery of whisking amplitude. CONCLUSIONS: Restoration of target reinnervation after peripheral nerve injury requires a complex mixture of trophic factors with a specific time course of availability for each of them.

Experimental Studies on Facial Nerve Regeneration.

Insufficient recovery after injury of a peripheral motor nerve is due to (1) inappropriate pathfinding as a result of axonal regrowth to inappropriate targets, (2) excessive collateral axonal branching at the lesion site, and (3) polyinnervation of the neuromuscular junctions (NMJs). The rat facial nerve model is often used because of its simple and reliable readout to measure recovery of function (vibrissal whisking). Over the last decades scientists have concentrated their efforts to combat mostly NMJ polyinnervation, because it turned out to be very difficult to reduce collateral axonal branching and impossible to navigate thousands of axons toward the original fascicles. In the past, several groups of scientists concentrated their efforts to reduce the activity-dependent polyinnervation of NMJs by electrical stimulation of the muscles (square 0.1 msec pulses at 5 Hz). The results showed no recovery of functions and a severe reduction in the number of innervated NMJs to approximately one fifth of those observed in intact animals. More recent experiments, however, have shown that motor recovery improved significantly following mechanical stimulation of the denervated facial muscles (vibrissal and orbicularis oculi) and that restored functions could invariably be linked to reduced polyinnervation at the NMJ while the number of innervated NMJ remained the same. These results suggest that clinically feasible and effective therapies could be developed and tested in the near future. Anat Rec, 302:1287-1303, 2019. © 2019 Wiley Periodicals, Inc.

Effect of surgically guided axonal regrowth into a 3-way-conduit (isogeneic trifurcated aorta) on functional recovery after facial-nerve reconstruction: Experimental study in rats.

BACKGROUND: The "post-paralytic syndrome" after facial nerve reconstruction has been attributed to (i) malfunctioning axonal guidance at the fascicular (branches) level, (ii) collateral branching of the transected axons at the lesion site, and (iii) intensive intramuscular terminal sprouting of regenerating axons which causes poly-innervation of the neuromuscular junctions (NMJ). OBJECTIVE: The first two reasons were approached by an innovative technique which should provide the re-growing axons optimal conditions to elongate and selectively re-innervate their original muscle groups. METHODS: The transected facial nerve trunk was inserted into a 3-way-conduit (from isogeneic rat abdominal aorta) which should "guide" the re-growing facial axons to the three main branches of the facial nerve (zygomatic, buccal and marginal mandibular). The effect of this method was tested also on hypoglossal axons after hypoglossal-facial anastomosis (HFA). Coaptational (classic) FFA (facial-facial anastomosis) and HFA served as controls. RESULTS: When compared to their coaptation (classic) alternatives, both types of 3-way-conduit operations (FFA and HFA) promoted a trend for reduction in the collateral axonal branching (the proportion of double- or triple-labelled perikarya after retrograde tracing was slightly reduced). In contrast, poly-innervation of NMJ in the levator labii superioris muscle was increased and vibrissal (whisking) function was worsened. CONCLUSIONS: The use of 3-way-conduit provides no advantages to classic coaptation. Should the latter be impossible (too large interstump defects requiring too long interpositional nerve grafts), this type of reconstruction may be applied. (230 words).

Effect of Pulsed and Continuous Ultrasound Therapy on the Degree of Collateral Axonal Branching at the Lesion Site, Polyinnervation of Motor End Plates, and Recovery of Motor Function after Facial Nerve Reconstruction.

The aim of the present study is to test whether ultrasound therapy of muscles denervated by nerve injury would improve the quality of their reinnervation by reduction of the collateral axonal branching at the lesion site and poly-innervation degree at the neuromuscular junctions. After transection and suture of the buccal branch of the facial nerve, pulsed or continuous type of ultrasound therapy was applied to the paralyzed whisker pad muscles of rats in the course of 2 months. Instead of reduction, we found a significant increase in the collateral axonal branching after continuous ultrasound therapy when compared to the branching determined after pulsed or sham ultrasound therapy. Both types of ultrasound therapy also failed to reduce the proportion of polyinnervated end plates in the reinnervated facial muscles. Accordingly, continuous ultrasound therapy failed to restore any parameter of the motor performance of the vibrissal hairs. Application of pulsed ultrasound therapy promoted slight improvements of the functional parameters angular velocity and acceleration. The inhomogeneous structural and functional results achieved after both types of ultrasound therapy let us conclude that further studies are required to evaluate its effects on peripheral nerve regeneration. Anat Rec, 302:1314-1324, 2019. © 2019 Wiley Periodicals, Inc.

Anatomic conditions for bypass surgery between rostral (T7-T9) and caudal (L2, L4, S1) ventral roots to treat paralysis after spinal cord injury.

Severe spinal cord injuries cause permanent neurological deficits and are still considered as inaccessible to efficient therapy. Injured spinal cord axons are unable to spontaneously regenerate. Re-establishing functional activity especially in the lower limbs by reinnervation of the caudal infra-lesional territories might represent an effective therapeutic strategy. Numerous surgical neurotizations have been developed to bridge the spinal cord lesion site and connect the intact supra-lesional portions of the spinal cord to peripheral nerves (spinal nerves, intercostal nerves) and muscles. The major disadvantage of these techniques is the increased hypersensitivity, spasticity and pathologic pain in the spinal cord injured patients, which occur due to the vigorous sprouting of injured afferent sensory fibers after reconstructive surgery. Using micro-surgical instruments and an operation microscope we performed detailed anatomical preparation of the vertebral canal and its content in five human cadavers. Our observations allow us to put forward the possibility to develop a more precise surgical approach, the so called "ventral root bypass" that avoids lesion of the dorsal roots and eliminates sensitivity complications. The proposed kind of neurotization has been neither used, nor put forward. The general opinion is that radix ventralis and radix dorsalis unite to form the spinal nerve inside the dural sac. This assumption is not accurate, because both radices leave the dural sac separately. This neglected anatomical feature allows a reliable intravertebral exposure of the dura-mater ensheathed ventral roots and their damage-preventing end-to-side neurorrhaphy by interpositional nerve grafts.

Recovery after spinal cord injury by modulation of the proteoglycan receptor PTPσ.

SCI is followed by dramatic upregulation of chondroitin sulfate proteoglycans (CSPGs) which limit axonal regeneration, oligodendrocyte replacement and remyelination. The recent discovery of the specific CSPGs signaling receptor protein tyrosine phosphatase sigma (RPTPσ) provided an opportunity to refine the therapeutic approach to overcome CSPGs inhibitory actions. In previously published work, subcutaneous (s.c.) delivery of 44 µg/day of a peptide mimetic of PTPσ called intracellular sigma peptide (ISP), which binds to PTPσ and blocks CSPG-mediated inhibition, facilitated recovery after contusive SCI. Since this result could be of great interest for clinical trials, we independently repeated this study, but modified the method of injury as well as peptide application and the dosage. Following SCI at the Th10-segment, 40 rats were distributed in 3 groups. Animals in group 1 (20 rats) were subjected to SCI, but received no treatment. Rats in group 2 were treated with intraperitoneal (i.p.) injections of 44 µg/day ISP (SCI + ISP44) and animals of group 3 with s.c. injections of 500 µg/day ISP (SCI + ISP500) for 7 weeks after lesioning. Recovery was analyzed at 1, 3, 6, 9 and 12 weeks after SCI by determining (i) BBB-score, (ii) foot-stepping angle, (iii) rump-height index, (iv) number of correct ladder steps, (v) bladder score and (vi) sensitivity (withdrawal latency after thermal stimulus). Finally, we determined the amount of serotonergic fibers in the preserved neural tissue bridges (PNTB) around the lesion site. Our results show that, systemic therapy with ISP improved locomotor, sensory and vegetative recovery which correlated with more spared serotonergic fibers in PNTB.

Constitutively reduced sensory capacity promotes better recovery after spinal cord-injury (SCI) in blind rats of the dystrophic RCS strain.

BACKGROUND: We compared functional, electrophysiological and morphological parameters after SCI in two groups of rats Sprague Dawley (SD) rats with normal vision and blind rats from a SD-substrain "Royal College of Surgeons" (SD/RCS) who lose their photoreceptor cells after birth due to a genetic defect in the retinal pigment epithelium. For these animals skin-, intramuscular-, and tendon receptors are major available means to resolve spatial information. OBJECTIVE: The purpose of this study was to check whether increased sensitivity in SD/RCS rats would promote an improved recovery after SCI. METHODS: All rats were subjected to severe compression of the spinal cord at vertebra Th8, spinal cord segment Th10. Recovery of locomotion was analyzed at 1, 3, 6, 9, and 12 weeks after SCI using video recordings of beam walking and inclined ladder climbing. Five functional parameters were studied: foot-stepping angle (FSA), rump-height index (RHI) estimating paw placement and body weight support, respectively, number of correct ladder steps (CLS) assessing skilled hindlimb movements, the BBB-locomotor score and an established urinary bladder score (BS). Sensitivity tests were followed by electrophysiological measurement of M- and H-wave amplitudes from contractions of the plantar musculature after stimulation of the tibial nerve. The closing morphological measurements included lesion volume and expression of astro- and microglia below the lesion. RESULTS: Numerical assessments of BBB, FSA, BS, lesion volume and GFAP-expression revealed no significant differences between both strains. However, compared to SD-rats, the blind SD/RCS animals significantly improved RHI and CLS by 6 - 12 weeks after SCI. To our surprise the withdrawal latencies in the blind SD/RCS rats were longer and the amplitudes of M- and H-waves lower. The expression of IBA1-immunoreactivity in the lumbar enlargement was lower than in the SD-animals. CONCLUSION: The longer withdrawal latencies suggest a decreased sensitivity in the blind SD/RCS rats, which promotes better recovery after SCI. In this way our results provide indirect support to earlier work showing, that hypersensitivity and chronic pain after contusive SCI impair the recovery of locomotor function.

The effect of myelotomy following low thoracic spinal cord compression injury in rats.

Myelotomy is a surgical procedure allowing removal of extravasated blood and necrotic tissue that is thought to attenuate secondary injury as well as promote recovery in experimental spinal cord injury (SCI) models and humans. Here we examined in rat whether myelotomy at 48 h after low-thoracic compressive SCI provided any benefit over a 12 week period. Compared to animals receiving SCI alone, myelotomy worsened BBB scores (p < 0.05) and also did not improve plantar stepping, ladder climbing, urinary bladder voiding or sensory function (thermal latency) during the 12-week period. Quantitative analyses of tissue sections at 12 weeks showed that myelotomy also did not reduce lesion volume nor alter immunohistochemical markers of axons in spared white matter bridges, microglia, astrocytes or serotinergic fibres. However, myelotomy reduced synaptophysin expression, a marker of synaptic plasticity. We conclude that further studies are required to evaluate myelotomy after SCI. (142 words).

Early and continued manual stimulation is required for long-term recovery after facial nerve injury.

INTRODUCTION: We previously have shown that manual stimulation (MS) of vibrissal muscles for 2 months after facial nerve injury in rats improves whisking and reduces motor end plate polyinnervation. Here, we seek to determine whether discontinuing or delaying MS after facial-facial anastomosis (FFA) leads to similar results. METHODS: Rats were subjected to FFA and received MS for (1) 4 months (early and continued), (2) the first but not the last 2 months (discontinued), or (3) the last 2 months (delayed). Intact animals and those not receiving MS (no MS) were also examined. RESULTS: Early and continued MS restored whisking amplitude to 43°, a value significantly higher compared with the discontinued, delayed, and no MS groups (32°, 24°, and 10°, respectively). Motor end plate polyinnervation occurred in all experimental groups but was significantly higher in the delayed group. DISCUSSION: Early and continued MS results in better recovery than when it is either discontinued or delayed. Muscle Nerve 57: 100-106, 2018.

Putative roles of soluble trophic factors in facial nerve regeneration, target reinnervation, and recovery of vibrissal whisking.

It is well-known that, after nerve transection and surgical repair, misdirected regrowth of regenerating motor axons may occur in three ways. The first way is that the axons enter into endoneurial tubes that they did not previously occupy, regenerate through incorrect fascicles and reinnervate muscles that they did not formerly supply. Consequently the activation of these muscles results in inappropriate movements. The second way is that, in contrast with the precise target-directed pathfinding by elongating motor nerves during embryonic development, several axons rather than a single axon grow out from each transected nerve fiber. The third way of misdirection occurs by the intramuscular terminal branching (sprouting) of each regenerating axon to culminate in some polyinnervation of neuromuscular junctions, i.e. reinnervation of junctions by more than a single axon. Presently, "fascicular" or "topographic specificity" cannot be achieved and hence target-directed nerve regeneration is, as yet, unattainable. Nonetheless, motor and sensory reinnervation of appropriate endoneurial tubes does occur and can be promoted by brief nerve electrical stimulation. This review considers the expression of neurotrophic factors in the neuromuscular system and how this expression can promote functional recovery, with emphasis on the whisking of vibrissae on the rat face in relationship to the expression of the factors. Evidence is reviewed for a role of neurotrophic factors as short-range diffusible sprouting stimuli in promoting complete functional recovery of vibrissal whisking in blind Sprague Dawley (SD)/RCS rats but not in SD rats with normal vision, after facial nerve transection and surgical repair. Briefly, a complicated time course of growth factor expression in the nerves and denervated muscles include (1) an early increase in FGF2 and IGF2, (2) reduced NGF between 2 and 14days after nerve transection and surgical repair, (3) a late rise in BDNF and (4) reduced IGF1 protein in the denervated muscles at 28days. These findings suggest that recovery of motor function after peripheral nerve injury is due, at least in part, to a complex regulation of nerve injury-associated neurotrophic factors and cytokines at the neuromuscular junctions of denervated muscles. In particular, the increase of FGF2 and concomittant decrease of NGF during the first week after facial nerve-nerve anastomosis in SD/RCS blind rats may prevent intramuscular axon sprouting and, in turn, reduce poly-innervation of the neuromuscular junction.

Anastomotic patterns of the facial parotid plexus (PP): A human cadaver study.

Details of the human facial parotid plexus (PP) are not readily accessible during ordinary anatomical teaching because of insufficient time and difficulties encountered in the preparation. For parotid and facial nerve surgery however, precise knowledge of PP is of crucial importance. The aim of this study was therefore to provide more details of PP in anatomic specimens. Following anatomical dissection, its location, syntopy and morphology were analyzed in 158 cervico-facial halves of 95 cadavers. The facial nerve (FN) divides into a larger temporo-facial and a smaller cervico-facial trunk. Both trunks branch, form PP, and thus form connections along six distinctive anastomotic types. These anastomoses may explain why accidental or essential severance of a supposed terminal facial branch fails to result in the expected muscle weakness. However, whereas earlier anatomical and clinical studies report connections between both trunks in 67-90% of the cases, our data indicate the presence of anastomoses only in 44%. One reason for this difference may be found in our microscope-assisted dissection in infratemporal regions from which the parotid gland has been removed. Thereby we tracked both FN-trunks in both directions - distally and proximally - and determined the exact origin of all terminal FN branches. This lower rate of occurrence of connections between both trunks reduces the chances of luckily preserved muscle innervation and enhances the risk of facial palsy after transection of a terminal branch. Accordingly, precise anatomical knowledge on PP should be renewed and transection of facial nerve branches avoided.

Comparison of trophic factors' expression between paralyzed and recovering muscles after facial nerve injury. A quantitative analysis in time course.

After peripheral nerve injury, recovery of motor performance negatively correlates with the poly-innervation of neuromuscular junctions (NMJ) due to excessive sprouting of the terminal Schwann cells. Denervated muscles produce short-range diffusible sprouting stimuli, of which some are neurotrophic factors. Based on recent data that vibrissal whisking is restored perfectly during facial nerve regeneration in blind rats from the Sprague Dawley (SD)/RCS strain, we compared the expression of brain derived neurotrophic factor (BDNF), fibroblast growth factor-2 (FGF2), insulin growth factors 1 and 2 (IGF1, IGF2) and nerve growth factor (NGF) between SD/RCS and SD-rats with normal vision but poor recovery of whisking function after facial nerve injury. To establish which trophic factors might be responsible for proper NMJ-reinnervation, the transected facial nerve was surgically repaired (facial-facial anastomosis, FFA) for subsequent analysis of mRNA and proteins expressed in the levator labii superioris muscle. A complicated time course of expression included (1) a late rise in BDNF protein that followed earlier elevated gene expression, (2) an early increase in FGF2 and IGF2 protein after 2 days with sustained gene expression, (3) reduced IGF1 protein at 28 days coincident with decline of raised mRNA levels to baseline, and (4) reduced NGF protein between 2 and 14 days with maintained gene expression found in blind rats but not the rats with normal vision. These findings suggest that recovery of motor function after peripheral nerve injury is due, at least in part, to a complex regulation of lesion-associated neurotrophic factors and cytokines in denervated muscles. The increase of FGF-2 protein and concomittant decrease of NGF (with no significant changes in BDNF or IGF levels) during the first week following FFA in SD/RCS blind rats possibly prevents the distal branching of regenerating axons resulting in reduced poly-innervation of motor endplates.