兔坐骨神经高压电损伤后早期电生理改变的实验研究

目的 研究家兔坐骨神经高压电损伤后早期电生理的变化规律。方法 新西兰家兔48只,分成2组。实验组40只,以1万V高压电电击右下肢,于伤后即刻、3、7、14、21d共5个时间组检测实验兔右下肢的肌电图（EMG）、运动神经传导速度（MNCV）、复合肌肉电位（CMAP）和皮层体诱发电位（SEP）。正常对照组8只家兔不作任何处理。结果 20只兔右侧坐骨神经的MNCV、CMAP、SEP在伤后3d全部测不出,提示为完全损伤。20只兔随伤后时间的推移,坐骨神经的MNCV逐渐减慢;CMAP和SEP的潜伏期逐渐延长,波幅逐渐降低。提示为不全损伤。两者肌电图失神经电位的变化则相似。结论 家兔坐骨神经被高压电击伤后早期的肌电图神经电图改变呈进行性加重。     

Application of quinidine on rat sciatic nerve decreases the amplitude and increases the latency of evoked responses

Purpose

Multi-modality electrophysiological techniques were performed to assess the effects of quinidine on peripheral nerve conduction.

Methods

Twenty-seven rats were treated with 1, 3, and 5 μmol quinidine in 0.1 ml 5 % glucose. The mixed-nerve somato-sensory evoked potential (M-SSEP), dermatomal-SSEP (D-SSEP), and compound muscle action potentials (CMAP) were evoked and recorded. After positioning Gelfoam strips saturated with quinidine and 5 % glucose around the left and right sciatic nerves, potentials were measured at baseline, immediately after treatment, every 15 min for the 1st hour, and every 30 min for the next 3 h. After 2 weeks, the walking behaviors and potentials were again analyzed and myelinated fibers in the sciatic nerve were counted.

Results

Quinidine applied directly to sciatic nerves reduced the amplitude and prolonged the latency in SSEPs and CMAP, compared to baseline and the contralateral right limbs (controls). This persisted for at least 4 h. After 2 weeks, electrophysiological tests and walking behavior showed no significant difference between the controls and experimental limbs. There was also no difference in the number of myelinated fibers in the sciatic nerves.

Conclusions

Quinidine decreases amplitude and prolongs latency in the sciatic nerve in a dose-related manner without local neural toxicity.     

LLLT actives MMP-2 and increases muscle mechanical resistance after nerve sciatic rat regeneration

The purpose of this study was to analyze the low-level laser therapy (LLLT) on metalloproteinase expression and the mechanical strength of skeletal muscle regeneration after peripheral nerve injury. Rats were subjected to crush injury of the right sciatic nerve, followed by LLLT (830 nm, 35, 70, 140, and 280 J/cm²) for 21 consecutive days. Functional gait analysis was performed at weekly intervals and the animals were sacrificed after the last evaluation at day 21 for collection of the gastrocnemius muscles, which were submitted to analysis of resistance, and the tibialis anterior, for evaluation of metalloproteinase-2 (MMP-2). The results were statistically analyzed at a significance level of 5%. The irradiated groups showed a significant decrease in the sciatic functional index and a significant increase in the mechanical strength when compared to the injured group with no treatment (p?<?0.05), with no significant difference among the energy densities used. While no difference among groups was observed for the activity of MMP-2 in pro-active band, at the intermediate band, the activity was significantly higher (p?<?0.05) for the groups irradiated with 35, 70, and 140 J/cm², and at the active band, the activity was significantly more intense in the group irradiated with 280 J/cm². The present study demonstrated that injury of the sciatic nerve, with consequent muscle denervation, are benefited by the laser therapy, which restores neuromuscular function, active MMP-2 and increases the maximum breaking strength.     

Low-level laser therapy improves repair following complete resection of the sciatic nerve in rats

The aim of this study is to analyze the effects of low-level laser therapy (LLLT) on the regeneration of the sciatic nerve in rats following a complete nerve resection. Male Wistar rats were divided into a control injury group, injury groups irradiated with a 660-nm laser at 10 or 50 J/cm², and injury groups irradiated with an 808-nm laser at 10 or 50 J/cm². Treatment began 24 h following nerve resection and continued for 15 days. Using the sciatic functional index (SFI), we show that the injured animals treated with 660 nm at 10 and 50 J/cm² had better SFI values compared with the control injury and the 808-nm groups. Animals irradiated with the 808-nm laser at 50 J/cm² show higher values for fiber density than do control animals. In addition, axon and fiber diameters were larger in animals irradiated with 660 nm at 50 J/cm² compared to the control group. These findings indicate that 660-nm LLLT is able to provide functional gait recovery and leads to increases in fiber diameter following sciatic nerve resection.     

Post-tetanic transcranial motor evoked potentials augment the amplitude of compound muscle action potentials recorded from innervated and non-innervated muscles

Background Context

Transcranial electrical stimulation used to produce motor evoked potentials (TES-MEPs) and subsequent compound muscle action potential (CMAP) recording is widely used to monitor motor function during surgery when there is risk of damaging the spinal cord. Nonetheless, some muscles do not produce CMAP amplitudes sufficient for intraoperative monitoring.

Acute Electrophysiological Effect of Pulsed Gallium–Arsenide Low-Energy Laser Irradiation on Isolated Frog Sciatic Nerve

We evaluated the acute electrophysiological effects of low-energy pulsed laser irradiation on isolated frog sciatic nerve measured by extracellular recording technique. A pulsed gallium–arsenide (GaAs) laser (wavelength: 904 nm, pulse duration 220 ns, peak power per pulse: 27 W, spot size: 0.28 cm², total applied energy density: 0.005–2.5 J/cm²) was used for the experiment. Sixty isolated nerves were divided into six groups (n=10), each of which received a different laser dose. In each group, action potentials were recorded before laser irradiation which served as the control data. The extracellular action potentials were recorded for each combination of 1, 3, 5, 7, 10, 13 and 15 minutes of irradiation time and 4, 8, 16, 32, 64 and 128 repetition frequency by using a BIOPAC MP 100 Acquisition System Version 3.5.7 (Santa Barbara, USA). Action potential amplitude, area, duration and conduction velocity were measured. Statistical evaluation was performed using repeated measures variance analysis by SPSS 9.0. There were no statistically significant differences for action potential amplitude, area and conduction velocity among the laser groups and control data (p>0.05). The study showed that low-energy GaAs irradiation at 4–128 Hz repetition frequencies administered for irradiation times of 1–15 min generates no effect on action potential amplitude, area, duration and conduction velocity in isolated frog sciatic nerve. Paper received 26 February 2001; accepted after revision 24 August 2001.     

Analysis of the variation in low-level laser energy density on the crushed sciatic nerves of rats: a morphological,quantitative, and morphometric study

The objective of this study was to evaluate three energy densities of low-level laser therapy (LLLT, GaAlAs, 780 nm, 40 mW, 0.04 cm²) for the treatment of lesions to peripheral nerves using the sciatic nerve of rats injured via crushing model (15 kgf, 5.2 MPa). Thirty Wistar rats (♂, 200–250 g) were divided into five groups (n?=?6): C—control, not injured, and irradiated; L0—injured nerve without irradiation; L4—injured nerve irradiated with LLLT 4 J/cm² (0.16 J); L10—injured nerve irradiated with LLLT 10 J/cm² (0.4 J); and L50—injured nerve irradiated with LLLT 50 J/cm² (2 J). The animals were sacrificed 2 weeks after the injury via perfusion with glutaraldehyde (2.5%, 0.1 M sodium cacodylate buffer). The nerve tissue was embedded in historesin, cut (3 μm), mounted on slides, and stained (Sudan black and neutral red). The morphological and quantitative analysis (myelin and blood capillary densities) and morphometric parameters (maximum and minimum diameters of nerve fibers, axon diameter, G-ratio, myelin sheath thickness) were assessed using the ImageJ software. ANOVA (parametric) or Kruskal-Wallis (nonparametric) tests were used for the statistical analysis. Groups L0, L4, L10, and L50 exhibited diminished values of all the quantitative and morphometric parameters in comparison to the control group. The morphological, quantitative, and morphometric data revealed improvement after injury in groups L4, L10, and L50 (irradiated groups) compared to the injured-only group (L0); the best results, in general, were observed for the L10 group after 15 days of nerve injury.     

Sciatic nerve course in adult patients with unilateral developmental dysplasia of the hip: implications for hip surgery

Background

Sciatic nerve injury is a disastrous adverse complication of surgery and can cause debilitating pain, functional impairment and poor quality of life. Patients with developmental dysplasia of the hip (DDH) have a high incidence of sciatic nerve injury after total hip arthroplasty (THA). A better understanding of the course of the sciatic nerve in patients with DDH may help minimise the risk of sciatic nerve injury after THA.

Methods

A total of 35 adult patients with unilateral DDH were enrolled in this retrospective study. We reviewed the patients’ computed tomography (CT) scans, which included the area from the iliac crest to below the lesser trochanter. The distance between the sciatic nerve and regional anatomic landmarks in four different sections on CT scans was measured to identify the course of the sciatic nerve.

Results

The distance from the sciatic nerve to the spine’s midline was shorter on the affected side than on the healthy side (p < 0.05); the same difference was also detected in the distance to the ilium/ischium outside the true pelvis (p < 0.05). The distance to the greater trochanter was longer on the affected side (p < 0.05). However, the two sides showed no significant difference in the distance from the sciatic nerve to the lesser trochanter (p > 0.05).

Conclusions

For patients with unilateral DDH, the sciatic nerve was located near the ischium and ilium but relatively far from the femur of the affected hip joint, compared to its location on the healthy side. These findings reveal that sciatic nerve becomes shorter in the affected low-limb and is relatively unlikely to be directly injuried using the posterolateral approach in patients with unilateral DDH.     

Use of enhanced stimulation voltage to determine the severity of compressive peripheral nerve injury

BACKGROUND: The aim of this study was to investigate whether enhanced stimulation voltage could be a predictor of the extent of injury in acute compressive peripheral nerve trauma. METHODS: The femoral nerves were exposed on both sides, in 11 anesthetized rabbits. Supramaximal stimulation voltage was used to produce a maximal-amplitude compound muscle action potential (CMAP) from the quadriceps femoris muscle. Afterward, the left femoral nerve was clipped for 1 minute, and the right femoral nerve for 5 minutes to produce an acute compressive injury. Immediately after removal of the clip, the proximal and distal sides of the clippage site were stimulated by gradually increased voltage until CMAPs were obtained. The same procedure was repeated at the 30th and 60th minutes. The ratio of the CMAP amplitudes obtained from proximal and distal stimulation was measured to establish a classification. RESULTS: The stimulation voltages and amplitudes of the CMAPs before clippage were similar with the after-clippage values obtained from distal stimulation (p > 0.05), but the after-clippage values obtained from proximal stimulation were different in both sides (p < 0.05). Doubled stimulation voltage was enough to obtain CMAPs on the left side, but eightfold the initial level was required on the right side. The amplitude ratios recovered to preinjury levels in all of the subjects on the left side, but only two showed recovery on the right side (p < 0.001). Histopathologically, there was axonal compression without discontinuity on the left side, whereas the fibers were dispersed on the right side. CONCLUSION: Stimulation voltage was found to discriminate the severity of the lesion in experimental peripheral nerve injury. Proximal to distal amplitude ratio seems to be a prognostic factor when the injury is less severe.     

Functional indices for sciatic,peroneal, and posterior tibial nerve lesions in the mouse

The sciatic functional index previously described in rats has proven to be a reliable index of functional recovery following sciatic nerve injury and repair. A similar functional assay of sciatic, peroneal, and posterior tibial nerve lesions was developed in a mouse model. Forty-eight C57/BL6 mice were randomly divided into 4 groups: sham surgery, sciatic nerve transection, peroneal nerve transection, and posterior tibial nerve transection. Preoperative and postoperative (48 hours) walking tracks were obtained. The pawprints were analyzed in a blinded fashion for measurements of print length (PL), toe spread (TS), intermediate toe spread (IT), and the orthogonal distance from the toe of one paw to the hind pad of the opposite paw (TOF). Multiple linear regression analysis was performed using these measurements to determine their significance and appropriate weighted contribution to the index formula for each nerve lesion. For the sciatic functional index, changes in the PL (P = 0.0092) and TS (P = 0.0008) were significant, resulting in an R² value of 0.88. For the peroneal functional index, only TS (P < 0.0001) was significant with R² = 0.83. For the posterior tibial index, only PL (P < 0.0001) was significant with R² = 0.89. Formulas for a sciatic, peroneal, and posterior tibial functional index were created based on the coefficients derived from the multiple linear regression analysis. The indices that were developed will allow investigators to assess functional recovery following specific nerve lesions in mice. © 1998 Wiley-Liss, Inc. MICROSURGERY 18:119-124 1998     

Diffusion tensor imaging and tractography of the sciatic and femoral nerves in healthy volunteers at 3T

Background

The aim was to clarify the normal fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the sciatic and femoral nerves at the level of the hip joint and to visualize the neural tracts with diffusion tensor imaging (DTI).

Methods

Twenty-four healthy volunteers (12 men and 12 women, age 20–29 years) underwent DTI for visualization with tractography and quantification of FA and ADC values on a 3 Tesla MRI (b value?=?800 s/mm², motion probing gradient, 11 directions, time to repeat/echo time?=?9000/72.6 ms, axial slice orientation, slice thickness?=?3.0 mm with no inter-slice gap, field of view?=?320?×?320 mm, 96?×?192 matrix, 75 slices, number of acquisitions?=?4). Regions of interest in the sciatic nerve were defined at the femoral head, the S1 root, and the midpoint levels. The femoral nerve was evaluated at 3–4 cm proximal to the femoral head level.

Results

The tractography of the sciatic and femoral nerves were visualized in all participants. The mean FA values of the sciatic nerve were increased distally from the S1 root level, through the midpoint, and to the femoral head level (0.314, 0.446, 0.567, p?=?0.001, respectively). The mean FA values of the femoral nerve were 0.565. The mean ADC values of the sciatic nerves were significantly lower in the S1 root level than in the midpoint and the femoral head level (1.481, 1.602, 1.591?×?10^?3?×?10^?3 mm²/s, p?=?0.001, respectively). The ADC values of the femoral nerve were 1.439?×?10^?3 mm²/s. FA and ADC values showed moderate to substantial inter- and intra-observer reliability without significant differences in gender or laterality.

Conclusion

Visualization and quantification of the sciatic and femoral nerves simultaneously around the hip joint were achieved in healthy young volunteers with DTI. Clinical application of DTI is expected to contribute to hip pain research.

     

Intraoperative Electrophysiological Studies to Predict the Efficacy of Neurolysis After Nerve Injury—Experiment in Rats

Compound muscle action potentials (CMAPs) can be used to analyze injury and recovery of nerve. This standardized study evaluates the value of CMAP analysis in predicting the long-term efficacy of neurolysis. CMAP amplitude is also used to determine the optimal extent of neurolysis. The left peroneal nerves of 30 rats were crushed. CMAPs were recorded for both crushed (left) and control (right) nerves. Fifteen rats underwent neurolysis 3 months post crush injury; the remaining 15 were sham controls and did not undergo neurolysis. CMAP measurements were taken after: (1) release of the nerve from the fascia, (2) opening the epineurium, and (3) opening the perineurium. At 3 months post crush injury, opening the epineurium resulted in a statistically significant increase in CMAP. CMAP increase with perineurial neurolysis was greater than with fascial release of the nerve but was not statistically different from that of epineurial release. At 5 months post crush injury, recovery of crushed nerves that underwent neurolysis was 90% and significantly less at 70.5% in rats not treated with neurolysis, according to CMAP analysis. Two conclusions can be made from this study. First, intraoperative neurophysiologic studies can monitor the immediate results of neurolysis and predict long-term results in the injured nerve. Second, epineurotomy is important in neurolysis, improves the function of the nerve, less invasive, and a slightly more effective technique than perineurotomy.     

Correlation between hepatic steatosis, hepatic volume, and spleen volume in live liver donors

Introduction

The purpose of this study was to evaluate the changes in liver fatty content and the volumes of liver and spleen after body weight reduction in potential living liver donors.

Materials and methods

Twenty-three potential living donors had fatty livers at pretransplantation sonography and computed tomography (CT). All were advised to undergo body weight reduction by exercise and diet control. A percutaneous core liver biopsy was performed in segment 5 of the liver in 22 donors to evaluate the hepatic fat content before and after body weight reduction. We compared the changes in the liver CT attenuation values and volume changes in the left and right lobes of the liver and the spleen before and after body weight reduction.

Results

The mean (SD) body weight, body mass index, and fatty content of the liver biopsy specimens were 73 (17) kg, 26.8 (4.4), and 16.9% (12.7%), respectively, before body weight reduction and 70 (15) kg, 25.3 (3.8), and 6.6% (3.7%), respectively, thereafter. These changes were significant. The CT attenuation values of the left and right lobes of the liver and spleen were 54 (11), 51 (11), and 52 (5) HU, respectively, before body weight reduction and 60 (8), 58 (6), and 53 (5) HU, respectively, thereafter. The mean CT attenuation value of the left lateral segment was greater than that of the right lobe both before and after body weight reduction. The volume of the left and right lobes and spleen changed from 497 (129) cm³ to 452 (99) cm³, 927 (237) cm³ to 846 (173) cm³, and 185 (65) cm³ to 186 (63) cm³, respectively, thereafter. The right and left lobe volume change ratios were 7.0% (10.6%) and 7.6% (11.1%), respectively, but showed no significant difference. Twenty of the 23 candidates were able to donate part of their liver.

Conclusion

Body weight reduction by exercise and diet control in potential living liver donors is effective to reduce the fatty content of the liver. Reversed percentage of the fatty content and volume of the liver was observed in these donors. The volumes of the right and left lobes of liver decreased significantly after body weight reduction. The volume changes were proportional.     

Unaffected contralateral S1 transfer for the treatment of lumbosacral plexus avulsion

Introduction

This study describes a new surgical strategy for lumbosacral plexus avulsion by transfer of the unaffected contralateral S1 nerve root.

Methods

A surgical reconstruction of the sacral nerve was performed on a 10-year-old boy with left lumbosacral plexus avulsion. The unaffected S1 nerve root (right side) is severed extradurally for transfer. A 25-cm long nerve graft from the common peroneal nerve of the affected side was used as donor nerve. One end of the nerve graft was anastomosed to the proximal stump of the right-sided extradural S1 nerve. The distal end of the nerve graft was divided into two fascicles and anastomosed to the left-sided inferior gluteal nerve and the branch of the sciatic nerve innervating the left-sided hamstrings.

Results

According to motor score of the British Medical Research Council (MRC) system, the strength of glutei and hamstrings improved to the level of M3 1.5 years after surgery.

Conclusions

The extradural S1 nerve root in the unaffected side can be considered as a suitable donor nerve for transfer in patients with root avulsion of the lumbar or sacral nerve plexus.     

Effect of the rate of prestretching a peripheral nerve on regeneration potential after transection and repair

We tested the influence of nerve stretch injury on nerve regeneration after cutting and suturing. An external fixator was used to lengthen the femur, and consequently the sciatic nerve, progressively, by 3mm/day (5%/day: group I) or 5mm/day (9%/day: group II). In both groups the total lengthening was 15mm, corresponding to approximately 23%–28% elongation of the sciatic nerve. Seven days after initiating nerve lengthening, the external fixator was removed and the nerve was transected and sutured. At 2, 4, 6, or 8 weeks after this suturing, semithin sections were prepared from the sciatic and tibial nerves. Although regeneration of nerve fibers was observed beginning at 2 weeks in all groups, nerve regeneration showed a delay only in group II at 6 weeks, when group I showed nerve regeneration as good as in the unstretched control group. Differences in nerve regeneration after nerve lengthening at different rates were considered the result of mechanical nerve injury, nerve degeneration, ischemia, and fibrosis, all made worse with more rapid lengthening. Nerve lengthening at a more moderate rate (3mm/day) did not appear to compromise regeneration.     

A comparison of the passage of regenerating axons through old degenerated nerve autografts and fresh nerve autografts in rats

Summary We have compared the passage of regenerating axons through old degenerated nerve autografts and fresh nerve autografts in two groups of Sprague Dawley rats. In one group the right sciatic nerve was divided and repaired with the graft taken from the distal segment of the left sciatic nerve, which had been severed 15 weeks before. In the other group the right sciatic nerve was repaired with the graft taken from the intact left sciatic nerve. Eight weeks later the myelinated axons were counted at three different locations in the grafted right sciatic nerve in both groups. The old degenerated nerve autografts were less effective in allowing the passage of regenerating axons than the fresh nerve autografts, but the difference was not great. This provides justification for the use of old degenerated nerve as an additional graft where a large number of autogenous nerve grafts are required, such as in the operative treatment of injuries to the brachial plexus.

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Résumé Les auteurs ont effectué un travail destiné à évaluer la possibilité du passage d'axones de régénération au travers d'autogreffes de nerfs dévitalisés depuis un certain temps, comparativement à celui d'autogreffes nerveuses fraîches. Dans ce but, une expérimentation a été menée sur deux groupes de rats blancs Sprague Dawley. Dans un des deux groupes, on a sectionné les nerfs sciatiques droits et on y a ensuite greffé les segments distaux de nerfs sciatiques gauches prélevés quinze semaines auparavant. Dans l'autre groupe, on a greffé sur les nerfs sciatiques droits sectionnés des segments prélevés sur les nerfs sciatiques gauches intacts. Après 8 semaines, on a comparé dans les deux groupes les axones myélinisés à trois endroits différents des nerfs sciatiques droits greffés: l'extrémité distale du segment proximal, le milieu de la greffe et l'extrémité proximale du segment distal. Les résultats ont montré que la capacité du nerf dégénéré à laisser passer les axones en régénérescence est 0.79 fois inférieure à celle du nerf frais (p[t]<0.05). Cependant la différence n'est pas très importante. Ceci signifie que des nerfs dégénérés peuvent être utilisés commes greffes complémentaires lorsqu'un grand nombre de greffes nerveuses autogènes est nécessaire, comme c'est le cas pour le traitement chirurgical des lésions du plexus brachial.

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Reprint requests to: H.J. Kim     

Comparative effects of wavelengths of low-power laser in regeneration of sciatic nerve in rats following crushing lesion

Peripheral nerves are structures that, when damaged, can result in significant motor and sensory disabilities. Several studies have used therapeutic resources with the aim of promoting early nerve regeneration, such as the use of low-power laser. However, this laser therapy does not represent a consensus regarding the methodology, thus yielding controversial conclusions. The objective of our study was to investigate, by functional evaluation, the comparative effects of low-power laser (660 nm and 830 nm) on sciatic nerve regeneration following crushing injuries. Twenty-seven Wistar rats subjected to sciatic nerve injury were divided into three groups: group sham, consisting of rats undergoing simulated irradiation; a group consisting of rats subjected to gallium–aluminum–arsenide (GaAlAs) laser at 660 nm (10 J/cm², 30 mW and 0.06 cm² beam), and another one consisting of rats subjected to GaAlAs laser at 830 nm (10 J/cm², 30 mW and 0.116 cm²). Laser was applied to the lesion for 21 days. A sciatic functional index (SFI) was used for functional evaluation prior to surgery and on days 7, 14, and 21 after surgery. Differences in SFI were found between group 660 nm and the other ones at the 14th day. One can observe that laser application at 660 nm with the parameters and methods utilised was effective in promoting early functional recovery, as indicated by the SFI, over the period evaluated.     

Assessment of Functional Recovery of Sciatic Nerve in Rats Submitted to Low-Level Laser Therapy with Different Fluences. An Experimental Study

Peripheral nerve lesions caused sensory and motor deficits along the distribution of the injured nerve. Numerous researches have been carried out to enhance and/or accelerate the recovery of such lesions. The objective of this study was to assess the functional recovery of sciatic nerve in rats subjected to different fluences of low-level laser therapy (LLLT). Thirty-six animals were randomly divided into four groups: one consisting of sham rats and three others irradiated with progressive fluencies of 10 J/cm², 40 J/cm² and 80 J/cm² of laser AsGaAl (830 nm) for 21 consecutive days. They were evaluated by the Sciatic Functional Index (SFI) method. The crush injury was performed by using a portable device with dead weight of 5,000 g whose load was applied for 10 min. A digital camera was used to record the footprints left on the acrylic track, before surgery and after, on the 7th, 14th, and 21st days. The results also showed that on the 7th day, there was a difference between the groups irradiated with 40 J/cm², when compared with the sham group (p < 0.05). On the 14th day the groups irradiated with 40 J/cm² and 80 J/cm² also presented better results when compared with sham, however, on the 21st day, no inter-group difference was found (p > 0.05). It was possible to observe that the LLLT at fluency of 40 J/cm² and 80 J/cm² had a positive influence on the acceleration of the functional nerve recovery.     

New predictors of complications in carotid body tumor resection

Objective

This study examined the relationship between two new variables, tumor distance to base of skull (DTBOS) and tumor volume, with complications of carotid body tumor (CBT) resection, including bleeding and cranial nerve injury.

Cross-Sectional Study of Weight-Bearing Activity on Proximal Femur Bone Mineral Density

In this cross-sectional study we investigated the effect of compressive and tensile forces applied on the proximal femur during weight-bearing activities. Ninety-seven men (29.9 ± 1.7 years) were divided into two groups: 69 exercisers who had practiced regular high-impact weight-bearing activities for at least 5 years and 28 controls who had been sedentary for at least 5 years. The maximum isometric hip abduction strength was measured. The bone mineral density (BMD) of the femoral neck and the greater trochanter was assessed using dual-energy X-ray absorptiometry (DXA). Controls were considered as the reference population to calculate the Z score. Mean BMD values of the femoral neck were 0.97 g/cm² on both sides in the exercisers and 0.83 g/cm² on the right side and 0.84 g/cm² on the left side in the controls. Mean BMD values of the greater trochanter were 0.86 g/cm² on the right side and 0.87 g/cm² on the left side in the exercisers, 0.73 g/cm² on the right side and 0.72 g/cm² on the left side in the controls. The BMD was significantly higher in exercisers at both trochanteric and cervical sites (P= 0.0001). Both left and right hip abduction strength was significantly greater in the exercisers than in the controls (P < 0.05) and was positively correlated to cervical and trochanteric BMD (P < 0.01). In the exerciser group, the trochanteric Z score was higher than the cervical Z score at both right (P= 0.06) and left (P= 0.002) sides. Therefore, the proximal femoral BMD was significantly greater in exercised subjects as compared with sedentary controls. The difference was observed at the level of both the femoral neck (where it is known anatomically that only compressive gravitational forces are exerted) and the greater trochanter (where it is known that tensile forces are exerted). This result suggests the participation of both compressive and tensile forces in the mechanisms by which exercise influences bone trophicity. Received: 19 November 1997 / Accepted: 7 August 1998