Functional Electrical Stimulation in Paraplegic Spastic Patients

Abstract: We are reporting on the clinical and physiological effects of 8 months of functional electrical stimulation (FES) of the quadriceps femoris muscle on 10 paraplegic patients. Each patient had muscle biopsies, computed tomography (CT) muscle diameter measurements, and knee extension strength testing both before and after 8 months of FES training. Skin perfusion was documented through infrared telethermography and xenon clearance; muscle perfusion was recorded through thallium scintigraphy. After 8 months of FES training, the baseline skin perfusion showed an 86% increase; muscle perfusion was augmented by 87%. Muscle fiber diameters showed an average increase of 59% after 8 months of FES training. Muscles in patients with spastic paresis showed an increase in aerobic and anaerobic muscle enzymes up to the normal range of healthy humans. The increment in muscle area, as visible on CT scans of the quadriceps femoris muscle, was 30%. Using FES, we were able to improve metabolism and to induce positive trophic changes in our patients' lower extremities. In spastic paraplegics, rising and walking achieved through FES are much better training than FES ergometer training. Larger muscle masses are activated, and the heart rate is increased; therefore, the impact on cardiovascular fitness and metabolism is much greater. This effectively addresses and prevents the problems that result from inactivity in paraplegic patients.     

Standing Up with Denervated Muscles in Humans Using Functional Electrical Stimulation

The use of electrical stimulation for denervated muscles is still considered to be a controversial issue by many rehabilitation facilities and medical professionals because prior clinical experience has shown that treating denervated muscle tissue using exponential current over a long time period constitutes an impossible task. Despite this fact, we managed to evoke tetanic contractions in denervated muscle using a long duration stimulation with anatomically shaped electrodes and sufficiently high amplitudes. The pulse amplitudes, which were being used for this purpose, exceeded by far the MED-GV and EC regulations (300 mJ/impulse). For this reason, an application has recently been submitted to have the EC regulations changed accordingly. It takes a tetanic contraction to achieve the desired muscle fiber tension, constituting a hypertrophic stimulus. It is also an appropriate means of exercise, which is capable of creating the metabolic and structural conditions needed (e.g, increased mitochondrial volume and capillary density) to obtain satisfactory muscle performance. With patients suffering from a complete spinal cord injury at level D12/L1, having motor and sensory loss in both lower extremities, we were able to train denervated muscle using long-duration stimulation, evoking single muscle contractions at first, soon followed by tetanic contractions against gravity. To increase the efficacy of this functional electrical stimulation (FES) strengthening program, we used ankle weights. With daily FES training over a period of 1-2 years, denervated muscle was exercised until it produced torques between 16 and 38 Nm in the m. quadriceps. With that muscle force, it is possible to stand up from a sitting position in parallel bars. Our results show that denervated muscle in humans is indeed trainable and can perform functional activities with FES. Furthermore, this method of stimulation can assist in decubitus prevention and significantly improve the mobility of paraplegics.     

In vivo assessment of conduction velocity and refractory period of denervated muscle fibers

Stimulation needle electromyography was used to study the muscle fiber conduction velocity and refractory period in 4 patients with long-term denervation of the lower limb muscles due to lesion of the conus cauda or cauda equina (2 untrained and 2 trained by functional electrical stimulation). In untrained patients, the results demonstrated that propagation velocity is reduced and refractory period of the muscle fiber is increased with time of denervation. The patients performing electrical stimulation training showed higher conduction velocities and reduced refractory period despite longer lasting denervation. This suggests that electrical stimulation training is effective to improve the electrical properties of the muscle fiber. Since the obtained data show a good correlation to other clinical tests and biopsy investigations, this method could serve as an additional measurement technique to specify the status of the denervated muscle. Further animal experiments and clinical studies are necessary to proof the results in comparison to more invasive established techniques.     

Electrical stimulation treatment of dog's denervated orbicularis oculi muscle

In this investigation, the electrophysiology and pathology of denervated orbicularis oculi muscles have been studied in dogs during chronic electrical stimulation. The orbicularis oculi muscles were unilaterally denervated in 8 dogs, and 4 of these muscles were directly stimulated on a daily basis for 75 days. No difference in minimum stimulus intensities evoking orbicularis oculi muscle twitch contraction appeared between denervated treated and nontreated muscles. A significant reduction of minimum stimulus intensities evoking upper eyelid complete closure (blink), however, was found in the denervated treated muscles between 10 and 30 days (p less than 0.01). At 28 and 75 days, orbicularis oculi muscle biopsies showed no difference in muscle fiber diameter between denervated treated and nontreated muscles. At 75 days, type II muscle fiber distribution, however, was significantly increased in denervated treated muscles compared with denervated nontreated muscles (p less than 0.01). These findings of orbicularis oculi muscle electrophysiology were consistent with a transient reversal of denervation changes by electrical stimulation, partially supported by muscle biopsies.     

Effects of Functional Electrical Stimulation on Denervated Laryngeal Muscle in a Large Animal Model

Bilateral vocal fold paralysis (BVCP) is a life‐threatening condition that follows injury to the Recurrent Laryngeal nerve (RLn) and denervation of the intrinsic laryngeal musculature. Functional electrical stimulation (FES) enables restoration and control of a wide variety of motor functions impaired by lower motor neuron lesions. Here we evaluate the effects of FES on the sole arytenoid abductor, the posterior cricoarytenoid (PCA) muscle in a large animal model of RLn injury. Ten horses were instrumented with two quadripolar intramuscular electrodes in the left PCA muscle. Following a 12‐week denervation period, the PCA was stimulated using a once‐daily training session for 8 weeks in seven animals. Three animals were used as unstimulated controls. Denervation produced a significant increase in rheobase (P < 0.001). Electrical stimulation produced a 30% increase in fiber diameter in comparison with the unstimulated control group (33.9 ± 2.6 µm FES+, 23.6 ± 4.2 µm FES?, P = 0.04). A trend toward a decrease in the proportion of type 1 (slow) fibers and an increase in type 2a (fast) fibers was also observed. Despite these changes, improvement in PCA function at rest was not observed. These data suggest that electrical stimulation using a relatively conservative set of stimulation parameters can reverse the muscle fiber atrophy produced by complete denervation while avoiding a shift to a slow (type 1) fiber type.     

Clinical Utility of Tc-99m MIBI SPECT/CT for Preoperative Localization of Parathyroid Lesions

We aimed to demonstrate the role of SPECT/CT in preoperative localization of parathyroid lesions in patients with hyperparathyroidism who had technetium-99m (Tc-99m) methoxyisobutylisonitrile (MIBI) dual-phase parathyroid scintigraphy. We evaluated retrospectively the scintigraphic data of 103 patients who had parathyroidectomy after Tc-99m MIBI dual-phase parathyroid scintigraphy with SPECT/CT. The planar and SPECT/CT images were evaluated separately to determine their efficacy in localizing parathyroid lesions. These results were then compared with surgical data. There were 84 female and 19 male patients whose mean age was 54?±?12 years. A total of 115 parathyroid lesions in 103 patients were resected during operations. In 87 patients, with both planar and SPECT/CT images, a total of 100 lesions could be detected correctly. In 11 patients, only SPECT/CT images could show 13 subcentimetric lesions. In three patients, three lesions were evaluated as parathyroid lesions both with planar and SPECT/CT images, but according to histopathologic evaluation, they came out to be nonparathyroidal lesions. In two patients, two parathyroid lesions could not be detected preoperatively neither with planar nor with SPECT/CT images. The lesion-based sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87 %, 99 %, 97.1 %, 95.3 %, and 95.8 % for planar images and 98.3 %, 99 %, 97.4 %, 99.4 %, and 98.8 % for SPECT/CT images, respectively. Tc-99m MIBI parathyroid scintigraphy should be a diagnostic modality of choice in preoperative evaluation of patients with hyperparathyroidism. SPECT/CT has an incremental value both in demonstrating subcentimetric lesions and in accurately localizing lesions anatomically.     

Prevention of quadriceps wasting after immobilization: an evaluation of the effect of electrical stimulation

Eighteen male and 20 female patients who underwent reconstruction of their anterior cruciate ligament (ACL) with a flap from the patellar tendon were randomly assigned into either closed cast, isometric muscle training and electric stimulation (ES group), or closed cast and isometric training alone (control group). The degree of quadriceps wasting was determined from computerized tomographic scans (CT) before and 6 weeks after surgery. Electrical stimulation was given with a battery operated stimulator that produced a rectangular asymmetric balanced biphasic pulse shape. The pulse rate was 40 Hz and the pulse width 300 microseconds. Patients received 30 min of stimulation three times daily during 5.5 weeks. Female control patients showed a larger decrease in quadriceps area on CT than male control patients (P less than .001). No significant difference was found between male electrically stimulated patients and control patients. In female patients, there was on the contrary, a highly significant difference in favor of electrical stimulation (P less than .001) When the different parts of the quadriceps were studied, a significantly lower degree of atrophy of the vastus medialis was found after electrical stimulation. Vastus lateralis did not show any difference. Measurements of CT attenuation, pre- and post-operatively, showed a decrease in attenuation of 17% for the vastus medialis and lateralis of the operated leg after immobilization, indicating an increase in fat content. In the rectus femoris, however, there was an increase in attenuation of 14.6%. Percutaneous muscle biopsies from the vastus lateralis obtained before, one week after, and 6 weeks after surgery revealed that the cross-sectional area of the individual muscle fibers decreased less in the electrically stimulated than in controls, but the difference was not significant. There were no differences between the two groups in the activity of an oxidative enzyme, citrate synthase, or a glycolytic enzyme, phosphofructokinase (PFK). We conclude that females reacted more favorably than males to electrical stimulation of quadriceps during an immobilization period after knee surgery.     

Stable muscle atrophy in long-term paraplegics with complete upper motor neuron lesion from 3- to 20-year SCI

STUDY DESIGN: Unrandomized trial. OBJECTIVES: To investigate the structural and functional relationships and the progression of muscle atrophy up to 20 years of spastic paraplegia. SETTING: Clinical follow-up in Vienna, Austria; muscle biopsies analyzed by light microscopy in Padova and by electron microscopy (EM) in Chieti, Italy. METHODS: Force was measured as knee extension torque; trophism by computer tomography scan; tissue composition and fiber morphology by histopathology and EM. RESULTS: In the long-term group of patients (17.0+/-2.6 years), force and size of thigh muscles were only slightly different from those of mid-term subjects (2.2+/-0.5 years). Histology and ultrastructure confirm that the difference in average size of muscle fibers between long-term and mid-term paralyzed leg muscles is actually very small. In addition, muscle fibers maintain the striated appearance characteristic of normal skeletal fibers even after 14-20 years of paralysis. Ultrastructural alterations of the activating and metabolic machineries, and the presence of fibers with lower motor neuron denervation features, may explain the low-force output and the reduced endurance of paretic muscles. CONCLUSION: The stable muscle atrophy that characterizes long-lasting spastic paraplegia suggests that there are no upper-time limits to begin a training program based on functional electrical stimulation.     

感觉神经保护延缓失神经性肌萎缩的实验研究

目的研究感觉神经延缓失神经肌萎缩的作用。方法成年雄性SD大鼠40只,随机分成两组,实验组(n=20)即感觉神经移植保护组,对照组(n=20)即纯失神经组。第一阶段:对照组仅横断肌皮神经。实验组完成近端锁骨上神经和远端肌皮神经吻合。第二阶段:第一阶段术后6个月,实验组及对照组完成胸小肌运动神经分支与肌皮神经远端的吻合。第二阶段术后4周及8周内,分别测定大鼠理毛实验、运动单位电位、肌肉湿重、肌肉HE染色、运动终板染色计数等。结果实验组术后第4及8周运动单位电位波幅明显高于对照组,电流刺激敏感度明显优于对照组。二头肌湿重恢复率、肌纤维直径、肌纤维截面积恢复率、运动终板数明显优于对照组。理毛实验于术后第2周时优势明显。结论近端感觉神经与远端运动神经端端吻合可有效延缓失神经肌肉萎缩。     

An experimental study on denervated muscle atrophy--effect of electrostimulation and comparison with immobilization muscle atrophy

The efficacy of causing muscle atrophy was compared among denervation, arthrodesis and tenotomy in rat anterior tibial muscle. Reduction of wet weight was most pronounced in denervated muscle and least in arthrodesed muscle. Histochemical investigation by ATPase stain revealed that atrophy of Type 1 and Type 2 fiber was more severe in denervated muscle group than in the other two groups. Type 2 fiber atrophy was dominant in denervated muscle and in arthrodesed muscle. Type 1 fiber atrophy was dominant in tenotomized muscle. The effect of electrostimulation on denervated muscle was investigated. Electrostimulation significantly reduced the degree of denervation atrophy. Four weeks after severance of peroneal nerve, tibial nerve-crossing was done and electrostimulation was continued for eight weeks. Recovery of wet weight of re-innervated muscle with electrostimulation was significantly better than that without electrostimulation. Electrostimulation applied to denervated muscle reduced the progress of atrophy and improved the recovery after nerve repair.     

Electrical stimulation of denervated muscles: first results of a clinical study

To evaluate the effects of electrical stimulation on denervated muscles in spinal cord injured humans, the EU Project RISE was started in 2001. The aims of this project are: to design and build sufficient stimulators; to develop stimulation protocols by means of mathematical models, animal experiments, and practice in humans with denervated lower limbs; to develop examination methods and devices for evaluation of electrical stimulation training effects; and to acquire basic scientific knowledge on denervated and stimulated denervated muscle. In the clinical study 27 spinal cord injured individuals were included, furthermore 13 pilot patients participated. After a series of initial examinations they underwent an electrical stimulation program for their denervated lower limb muscles. Some of the patients have already follow up examinations. A marked increase of muscle mass and quality was observed, the trophic situation of the denervated lower limbs had improved obviously.     

Levator ani muscle in women with genitourinary prolapse: Indirect assessment by muscle histopathology

The objective of this study was to assess the state of innervation in levator ani muscle sites using muscle histopathology. Asymptomatic women and patients with genitourinary prolapse were included. Histopathologic analysis allows indirect assessment of a muscle's innervation. Therefore, levator ani muscle was collected in a standardized fashion during abdominal surgery and frozen in the operating room using isopentane slush cooled by liquid nitrogen. Serial sections of levator ani muscle in cross-section were studied with standard histochemical and immunohistochemical techniques. The staining patterns from these histochemical techniques allowed quantitative determination of the ratios of fiber types I, IIA, and IIB and their fiber diameters. Objective assessment of fiber type grouping was performed. The distribution of both fiber type percentage and diameter were non-parametric. Therefore, the Mann-Whitney U-test was used to analyze the data for statistical differences between the means for these variables. There was no statistical difference in levator ani muscle fiber type percentage and diameter in patients with prolapse and/or urinary incontinence when compared to asymptomatic women. Levator ani muscles have a higher proportion of slow fibers (66%) than found in other human female muscle (48%). There was no evidence for denervation/reinnervation in any of the biopsy specimens. In this study, levator ani muscle biopsies from incontinent and/or prolapse patients were neither denervated nor reinnervated. © 1996 Wiley-Liss, Inc.     

用纤颤电位波幅衡量失神经肌肉萎缩程度的临床研究

目的研究失神经支配肱二头肌纤颤电位波幅的变化规律，并探索其与肌肉萎缩程度的关系。方法１９９５年８月～１９９６年１２月，检测１７３块因臂丛神经损伤致完全失神经支配的肱二头肌纤颤电位并计算其波幅；６３例在检测同一部位取肌组织送病理检查。被检肌肉行ＡＴＰ酶染色，测定Ｉ、Ｉ型肌纤维面积。结果纤颤电位的波幅和肌纤维的横断面积与失神经时间呈负相关；失神经后第５、６个月及１年以后为纤颤电位波幅的显著下降期；失神经后第４个月为肌纤维的显著萎缩期。纤颤电位的波幅与肌纤维的横截面积呈正相关；男性纤颤电位的波幅及ＩＩ型肌纤维面积均较女性为高（Ｐ＜０．０５）。结论纤颤电位波幅与肌纤维萎缩状态相一致，可作为评估肌肉萎缩程度的定量指标     

Effects of Carnitine on Preconditioned Latissimus Dorsi Muscle at Different Burst Frequencies

A bstract Exercise and electrical stimulation may result in a decrease in carnitine levels associated with preconditioned latissimus dorsi muscles. Therefore, the effects of exogenous carnitine were studied in a model of latissimus dorsi muscle contraction. Twelve dogs were studied. Under anesthesia, the latissimus dorsi was placed around an implantable mock circulation system. The muscle was made fatigue-resistant with the aid of chronic low-frequency electrical stimulation. Six animals received carnitine 0.15 mmol/kg; the other six served as control. The muscles were stimulated with 20, 43, and 85 Hz pulse training. During the 90-minute stimulation period, the pressure that developed in the mock circulation was measured at 15 minute intervals. The changes in ATP and lactate levels were measured every 30 minutes. Stimulations at 20 and 43 Hz did not result in any change in pressure or metabolic data over the course of 90 minutes of stimulation. When the 85 Hz burst was applied, ATP levels decreased, while lactate levels increased, with an associated drop in pressure in the control group. ATP and lactate levels were, respectively, 13.8 ± 1.4 μmol/g and 15.0 ± 4.0 μmol/g in the carnitine group and 10.3 ± 1.1 μmol/g and 23.0 ± 3.0 μmol/g in the control group at the end of 90 minutes (p < 0.05). The pressure at the same time interval was 74 ± 4 mmHg in the control group, and 85 ± 3 mmHg in the carnitine group (p < 0.05). In this study, we demonstrated that carnitine administration enhances muscle performance in terms of metabolic and pressure changes during high-frequency electrical stimulation at 85 Hz.     

The effect of body weight-supported treadmill training on muscle morphology in an individual with chronic, motor-complete spinal cord injury: A case study

OBJECTIVE: The purpose of this pilot study was to examine the effects of 4 months of thrice-weekly body weight-supported treadmill training (BWSTT) on skeletal muscle morphology in a woman (age 27 y) with chronic, motor-complete (ASIA B) spinal cord injury (SCI). METHODS: The participant performed passive thrice-weekly BWSTT for 4 months (48 total sessions) with manual assistance from therapists. Muscle biopsies of the vastus lateralis were taken prior to the beginning of the training program as well as following the completion of 4 months of training. Histochemical analysis was utilized to evaluate changes in muscle fiber size and type following training. RESULTS: At baseline, vastus lateralis muscle biopsies showed evidence of fiber atrophy and fiber type redistribution typical of persons with SCI, with mean fiber areas (and % distributions) of type I, type IIa and type IIx fibers being 3474 microm2 (1.3%), 3146 microm2 (30.8%) and 1284 microm2 (68.0%), respectively. Following training, there were increases in treadmill walking speed (pre: 1.0km/h; post: 2.5km/h) and distance walked/session (pre: 500m; post: 1875m). Vastus lateralis mean fiber area increased by 27.1% and type I fiber % distribution increased to 24.6%, whereas type IIa and type IIx fiber % distributions both decreased following training. CONCLUSION: These data indicate that 4 months of thrice-weekly BWSTT improved muscle morphology in an individual with chronic, motor-complete SCI.     

Reanimation of paralyzed laryngeal muscles by electrical stimulation synchronized with inspiration.

OBJECTIVE: To determine the effects of electrical stimulation on denervated cat posterior cricoarytenoid (PCA) muscle. STUDY DESIGN AND SETTING: This study was conducted on six cats with PCA muscle denervation. All animals were sacrificed 12 weeks after surgery and the glottal area in the live animals and the fiber diameters of PCA muscle were obtained. RESULTS: Signals synchronized with inspiration were recorded and transmitted to stimulate PCA muscle. The abduction of the paralyzed vocal cord during inspiration was observed; this allows enough flow of air through the larynx to maintain the respiration. The stimulated fiber diameters of PCA muscle were different from that of nonstimulated (P < 0.01). Although all denervated muscles were degenerated, electrical stimulation was used to prevent muscular atrophy. CONCLUSIONS: This study indicates that electrical stimulation of the PCA muscle synchronized with inspiration could restore the abduction of a paralyzed vocal cord and prevent the denervated muscles from atrophying. SIGNIFICANCE: Electrical stimulation synchronized with inspiration may lead to reanimation of paralyzed laryngeal muscles.     

Muscle fiber regeneration in human permanent lower motoneuron denervation: relevance to safety and effectiveness of FES-training, which induces muscle recovery in SCI subjects

Morphologic characteristics of the long-term denervated muscle in animals suggest that some original fibers are lost and some of those seen are the result of repeated cycles of fiber regeneration. Muscle biopsies from lower motoneuron denervated patients enrolled in the EU Project RISE show the characteristics of long-term denervation. They present a few atrophic or severely atrophic myofibers dispersed among adipocytes and connective tissue (denervated degenerated muscle, DDM). Monoclonal antibody for embryonic myosin shows that regenerative events are present from 1- to 37-years postspinal cord injury (SCI). After 2- to 10-years FES-training the muscle cryosections present mainly large round myofibers. In the FES-trained muscles the regenerative events are present, but at a lower rate than long-term denervated muscles (myofiber per mm2 of cryosection area: 0.8 +/- 1.3 in FES vs. 2.3 +/- 2.3 in DDM, mean +/- SD, P = 0.011). In our opinion this is a sound additional evidence of effectiveness of the Kern's electrical stimulation protocol for FES of DDM. In any case, the overall results demonstrate that the FES-training is safe: at least it does not induce more myofiber damage/regeneration than denervation per se.     

Restoration of Paralyzed Orbicularis Oculi Muscle Function by Controlled Electrical Current

A canine model of facial nerve paralysis was studied to apply controlled electrical current to the peripherally denervated orbicularis oculi muscle, in the attempt to effectively restore the absent function of this denervated muscle. After unilateral facial nerve neurotmesis was performed in eight dogs, the denervated orbicularis oculi muscles of four dogs were electrically stimulated for 75 postoperative days (40 min/day). Denervated and normal orbicularis oculi muscles were electrophysiologically studied and compared with the Student t test. During the study period, minimum closure of denervated treated orbicularis oculi muscles was evoked with average stimulus strength (80-ms duration) of 1.61 ± 0.22 log mA × ms. not significantly different from that of denervated nontreated or normal orbicularis oculi muscles. From days 10 through 30 only, maximum closure of denervated treated orbicularis oculi muscles was achieved with mean pulse strength (80-ms duration) of 2.37 ± 0.09 log mA × ms, significantly lower (P <. 01) than that evoking the same type of contraction from denervated nontreated muscles (80-ms duration, mean 2.83 ± 0.10 log mA × ms). In addition, denervated treated muscle pulse strength eliciting maximum contraction was not significantly different from that of normal orbicularis oculi muscles during the same period. This finding was not observed, however, from day 40 through the end of the study. This investigation demonstrates (1) the transient reversal of denervation changes of paralyzed orbicularis oculi muscle by daily electrical stimulation, and (2) the feasibility of restoring orbicularis oculi muscle function by controlled electrical current.     

Functional electrical stimulation of long-term denervated, degenerated human skeletal muscle: estimating activation using T2-parameter magnetic resonance imaging methods

Abstract:  Functional electrical stimulation (FES) of long-term denervated, degenerated human skeletal muscle has proven to be a suitable method for improving a number of physiological parameters. The underlying mechanisms of activation of a denervated muscle fiber can be described with suitably modified and extended Hodgin-Huxley type models, coupled with three-dimensional (3D) finite element models of the surrounding electrical field. Regions of activation within a muscle can be determined using a 3D computer model. However, simulation results have not yet been validated experimentally. During and immediately after exercise, muscle shows increased T2-relaxation times. It is thus possible to estimate muscle activation noninvasively and spatially resolved with the magnetic resonance imaging (MRI) method of T2 mapping, which was, therefore, chosen as a suitable validation approach. Six patients were scanned prior to FES training with a multislice multiecho MSME-sequence at 3 Tesla and then asked to perform one of their regular daily training-sessions (leg extensions). Subjects were then repositioned in the MR-scanner and two to five postexercise scans were recorded. Pre- and postexercise scans were coregistered and T2-parameter maps were calculated. Regions of interest (ROIs) were drawn manually around quadriceps femoris and its antagonists. Activation was detected in all patients. In well-trained patients, activation in the quadriceps was found to be considerably higher than in its antagonists. These experimental results will help further improve existing models of FES of denervated degenerated human skeletal muscle.     

Restoration of muscle volume and shape induced by electrical stimulation of denervated degenerated muscles: qualitative and quantitative measurement of changes in rectus femoris using computer tomography and image segmentation

Abstract:  This study demonstrates in a novel way how volume and shape are restored to denervated degenerated muscles due to a special pattern of electrical stimulation. To this purpose, Spiral Computer Tomography (CT) and special image processing tools were used to develop a method to isolate the rectus femoris from other muscle bellies in the thigh and monitor growth and morphology changes very accurately. During 4 years of electrical stimulation, three-dimensional (3D) reconstructions of the rectus femoris muscles from patients with long-term flaccid paraplegia were made at different points in time. The growth of the muscle and its changes through the time period are seen in the 3D representation and are measured quantitatively. Furthermore, changes in shape are compared with respect to healthy muscles in order to estimate the degree of restoration. The results clearly show a slow but continuing muscle growth induced by electrical stimulation; the increase of volume is accompanied by the return of a quasi-normal muscle shape. This technique allows a unique way of monitoring which provides qualitative and quantitative information on the denervated degenerated muscle behavior otherwise hidden.