Denervation and reinnervation of fast and slow muscles. A histochemical study in rats.

A histochemical study, using myosin-adenosine triphosphatase activity at pH 9.4, was conducted in soleus and plantaris muscles of adult rats, after bilateral crushing of the sciatic nerve at the sciatic notch. The changes in fiber diameter and per cent composition of type I and type II fibers plus muscle weights were evaluated along the course of denervation-reinnervation curve at 1, 2, 3, 4 and 6 weeks postnerve crush. The study revealed that in the early denervation phase (up to 2 weeks postcrush) both the slow and fast muscles, soleus and plantaris, resepctively, atrophied similarly in muscle mass. Soleus increased in the number of type II fibers, which may be attributed to "disuse" effect. During the same period, the type I fibers of soleus atrophied as much or slightly more than the type II fibers; whereas the type II fibers of plantaris atrophied significantly more than the type I fibers, reflecting that the process of denervation, in its early stages, may affect the two fiber types differentially in the slow and fast muscles. It was deduced that the type I fibers of plantaris may be essentially different in the slow (soleus) and fast (plantaris) muscles under study. The onset of reinnervation, as determined by the increase in muscle weight and fiber diameter of the major fiber type, occurred in soleus and plantaris at 2 and 3 weeks postcrush, respectively, which confirms the earlier hypotheses that the slow muscles are reinnervated sooner than the fast muscles. It is suggested that the reinnervation of muscle after crush injury may be specific to the muscle type or its predominant fiber type.

Motor power differences within the first two weeks post-SCI in cervical spinal cord-injured quadriplegic subjects.

The purpose of this study was to confirm the clinical impression that motor power significantly changed within the first 2 weeks after a spinal cord injury (SCI) and to determine the time for motor power assessment within the first 2 weeks post injury that best correlated with motor power determined 6 months post-SCI. Our hypothesis was that within the first 2 weeks postinjury, the manual muscle test (MMT) scores would change significantly from the < or = 24 h examination and that the post-24 h evaluations of strength would have a higher correlation with the 6 month measure of motor outcome than the evaluation of strength performed < or = 24 h after SCI. The biceps, extensor carpi radialis, triceps, flexor digitorum profundus, and interosseous muscle strength was measured in 40 subjects using the MMT (muscles graded 0/5 to 5/5) at < or = 24 h, 72 h, 1 week, 2 weeks, 3 months, and 6 months post-SCI. Upper extremity motor index scores (MIS) obtained at the four testing periods within 2 weeks of injury were analyzed using a Friedman analysis of variance with Duncan's post-hoc tests to identify significant differences. Separate analyses were performed on subgroupings of the total sample based on the strength of the most rostral key muscle having less than antigravity strength. There were three groups evaluated: initial MMT 0/5 (n = 22), initial MMT 1-1.5/5 (n = 17), and initial MMT 2-2.5/5 (n = 13).(ABSTRACT TRUNCATED AT 250 WORDS)

Wrist strength measured by myometry as an indicator of functional independence.

The purpose of this study was to show that independence of self care activities of motor complete quadriplegic patients related better to the force of contraction of the wrist extensor (WE) muscles measured by a hand held myometer than to the manual muscle test (MMT) for grades 3 to 5. The patients (n = 24), identified by having unilaterally or bilaterally functional WE muscle (MMT > or = 3/5) with bilateral elbow extensor (EE) muscles < 3/5, were evaluated at 2 to 6 months after injury for four feeding activities utilizing the Quadriplegia Index of Function (QIF). We found 54% were independent drinking from a cup, 58% using a spoon or fork, 13% cutting food, and 23% pouring liquids. Comparisons were made between right, left, and bilateral mean myometry scores and median MMT scores for each of the QIF activities. The independent group of patients had myometry scores 54 to 140% greater (p < 0.05) than those patients dependent in the self care activity except when the right or left WE myometric score was analyzed for cutting food (p = 0.1). MMT comparisons showed no significant median score differences in any activity performed. There were no patients with only one WE muscle > or = 3/5 (n = 9) who were able to cut food or pour liquids independently. In conclusion, myometry appeared to be a better indicator than the MMT for some self care activities evaluated utilizing the Quadriplegia Index of Function.

The relationship between the functional abilities of patients with cervical spinal cord injury and the severity of damage revealed by MR imaging.

BACKGROUND AND PURPOSE: The appearance of the damaged spinal cord after injury correlates with initial neurologic deficit, as determined by the American Spinal Injury Association grade and manual muscle test score, as well as with recovery, as assessed by manual muscle test scores. The purpose of this study was to determine whether the presence of spinal cord hemorrhage and the size and location of spinal cord edema on MR images is predictive of functional recovery in survivors of cervical spinal cord injury (SCI). METHODS: The degree of damage to the cervical spinal cord was measured on the MR images of 49 patients who underwent imaging within 72 hours of sustaining SCI. The effects of hemorrhage and length/location of edema on changes in the value of the motor scale of the functional independence measure (FIM) were assessed on admission to and discharge from rehabilitation. RESULTS: Patients without spinal cord hemorrhage had significant improvement in self-care and mobility scores compared with patients with hemorrhage. There was no significant effect of spinal cord hemorrhage on changes in locomotion and sphincter control scores. The rostral limit of edema positively correlated with admission and discharge self-care scores and with admission mobility and locomotion scores. Edema length had a negative correlation with all FIM scales at admission and discharge. CONCLUSION: The imaging characteristics of cervical SCI (hemorrhage and edema) are related to levels of physical recovery as determined by the FIM scale. Imaging factors that correlate with poor functional recovery are hemorrhage, long segments of edema, and high cervical locations.

Functional MR imaging of the human cervical spinal cord.

BACKGROUND AND PURPOSE: Although research with functional MR imaging of the brain has proliferated over the past 5 years, technical limitations, such as motion, chemical shift, and susceptibility artifacts, have impeded such research in the human spinal cord. The purpose of this investigation was to determine whether a reliable functional MR imaging signal can be elicited from the cervical spinal cord during simple motor activity. METHODS: Subjects performed three different motor tasks that activate different segments of the spinal cord. Gradient-echo-planar imaging on a 1.5-T clinical unit was used to image cervical spinal cords of human subjects. Another group of subjects was imaged while performing isometric exercise to study the relationship between the blood oxygenation level-dependent (BOLD) signal and applied force. RESULTS: Task-dependent BOLD activity was detected in all subjects. Signal amplitude varied between 0.5% and 7%. Moreover, a linear relationship was found between the applied force and the signal amplitude during isometric exercise. While regions of activation were distributed throughout the spinal cord, concentrated activity was found in the anatomic locations of expected motor innervation. CONCLUSION: The functional MR imaging signal can be reliably detected with motor activity in the human cervical spinal cord on a 1.5-T clinical unit. The location of neural activation has an anatomic correspondence to the myotome in use. The strength of the BOLD signal is directly proportional to the level of muscular activity.

Compensatory hypertrophy of the soleus in tumor-bearing rats.

Compensatory hypertrophy of the rat soleus was compared between normal rats (N) and rats bearing a non-metastasizing mammary tumor (TB). Two weeks after the tumor inoculation, introduced subcutaneously on the midline of the upper back, the two groups of rats underwent unilateral tenotomy of the plantaris and gastrocnemius muscles to induce functional overload or compensatory hypertrophy of the soleus. One week later, the body weight (BW), wet muscle weights (MW), percent of Type I (slow-twitch) and Type II (fast-twitch) muscle fibers and contractile parameters of the isometric twitch (Pt) and tetanic (Po) tensions were evaluated. The TB animals did not show any signs of cancer cachexia. The sham-operated control soleus muscles of the two groups were similar in wet MW, maximum isometric Pt and Po. The latent period (LP), the contraction time (CT), the half relaxation time (HRT) and the number of Type I (slow-twitch) fibers were increased significantly. The hypertrophied muscles in the N and TB rats showed significant declines in the maximum isometric Pt, compared to their respective controls. These data suggest that the compensatory hypertrophy of muscle is expressed similarly in both the normal and tumor-bearing rats but that it interferes with the generation of isometric twitch tension in the muscle.

Capillary fiber ratio and electrolyte content of compensatory hypertrophied rat soleus.

Capillary-to-fiber ratio and the content (mu moles/g muscle) of Na, K, Mg, Ca and Zn was measured in compensatory hypertrophied (CH) soleus muscles of adult Sprague-Dawley rats. The soleus hypertrophy was induced by unilateral tenotomy of the gastrocnemius and the plantaris muscles. Seven days after synergistic tenotomy the compensatory hypertrophied Soleus muscles showed no difference in the capillary-fiber ratio, Sr-extractable calcium ([Ca]Ext.) or the total content of Na, K, Mg and Zn. However, compared to the contralateral control side, the CH muscles showed an increase in the wet muscle weight (31.6%, P less than 0.01) and a significant decline (57.1%, P less than 0.05) in the residual calcium ([Ca]Res.) and 43.2% (P less than 0.05) decrease in the total calcium ([Ca]Total) content. It is concluded that during compensatory hypertrophy of skeletal muscles, the residual Ca reserves are significantly depleted, which may lead to a lower isometric tension generation in the muscle.

Closed reduction of traumatic cervical spine dislocation using traction weights up to 140 pounds.

The purpose of this study was to demonstrate that Gardner-Wells skull tong traction up to 140 lb was both safe and effective in reducing dislocation, without fractures, of facet joints involving the C4-C7 vertebral bodies when applied by experienced practitioners in a spinal cord injury center under close scrutiny. Twenty-four awake patients were selected for the study (age range, 16-82 years). These patients were evaluated for the number of millimeters (7-17 mm) of dislocation as measured from the posterior aspect of the superior vertebral body to the posterior aspect of the inferior vertebral body at the level of injury. The maximum weight required to produce the reduction of the facet joints and the time from the onset of traction were recorded. The patients' neurologic status was monitored before traction, after each increment in weight applied, and after reduction. Careful examination of motor function and sensation was done and recorded at each interval. The 24 patients with cervical spine dislocation of the facet joints underwent successful reduction with traction weights (range, 10-140 lb). Seventeen patients required weights of more than 50 lb. The traction procedures lasted for a period of 8-187 minutes per procedure. Worsening neurologic status did not occur in any of the patients involved in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Neurologic outcome of early versus late surgery for cervical spinal cord injury.

STUDY DESIGN: A prospective analysis evaluating neurologic outcome after early versus late surgery for cervical spinal cord trauma. OBJECTIVES: The study was conducted to determine whether neurologic and functional outcome is improved in traumatic cervical spinal cord-injured patients (C3-T1, American Spinal Injury Association grades A-D) who had early surgery (<72 hours after spinal cord injury) compared with those patients who had late surgery (>5 days after spinal cord injury). SUMMARY OF BACKGROUND DATA: There is considerable controversy as to the appropriate timing of surgical decompression and stabilization for cervical spinal cord trauma. There have been numerous retrospective studies, but no prospective studies, to determine whether neurologic outcome is best after early versus late surgical treatment for cervical spinal cord injury. METHODS: Patients meeting appropriate inclusion criteria were randomized to an early (<72 hours after spinal cord injury) or late (>5 days after spinal cord injury) surgical treatment protocol. The neurologic and functional outcomes were recorded from the acute hospital admission to the most recent follow-up. RESULTS: Comparison of the two groups showed no significant difference in length of acute postoperative intensive care stay, length of inpatient rehabilitation, or improvement in American Spinal Injury Association grade or motor score between early (mean, 1.8 days) versus late (mean, 16.8 days) surgery. CONCLUSIONS: The results of this study reveal no significant neurologic benefit when cervical spinal cord decompression after trauma is performed less than 72 hours after injury (mean, 1.8 days) as opposed to waiting longer than 5 days (mean, 16.8 days).

Traumatic focal posterior tibialis muscle denervation.

The purpose of this case presentation is to demonstrate posterior tibialis muscle (PTM) denervation as a cause of traumatic plantarflexion inversion weakness. In a 42-year-old woman, severe pain, swelling, and ecchymosis over the medial aspect of her left ankle developed after she twisted it while playing tennis. Plantarflexion inversion weakness developed (grade 3/5). The strength of all other muscle groups of the lower extremity was normal. Her pin and light touch sensation were normal in the left lower extremity. Deep tendon reflexes were equal and active at both knees and ankles. A magnetic resonance image of the left leg, ankle, and foot performed 1 month after injury demonstrated an intact posterior tibialis tendon behind the medial malleolus and edema-like increased signal intensity in the PTM on the T1-weighted image consistent with denervation. On electromyographic testing, there were continuous fibrillation and positive sharp wave potentials in every site tested in the PTM without any voluntary motor unit activity. The left extensor hallucis, left gastrocnemius, and lumbar paraspinal muscles were normal. In conclusion, combined magnetic resonance imaging and electromyographic studies supported denervation of the PTM as the cause of plantarflexion inversion weakness, rather than posterior tibialis tendon rupture in this patient.

Muscle atrophy in rheumatoid arthritis.

The purpose of this paper is to describe some research opportunities in the area of muscle atrophy secondary to arthritis. Future research should utilize quantitative methods of evaluating muscle atrophy such as computerized tomography or ultrasonography. The gross muscle atrophy should be further characterized by muscle fiber type measurements. These techniques as well as biochemical determinations should be utilized to identify mechanisms of muscle atrophy as well as determine ideal methods for reversing muscle atrophy and weakness.

Disseminated fat necrosis: a rehabilitation challenge.

Disseminated fat necrosis (DFN) is a rare complication of pancreatic disease characterized by subcutaneous nodules, visceral effusions, osseous intramedullary fat necrosis, and arthritis. The rehabilitation of a 33-year-old patient with DFN is described here. The patient had a history of alcoholic pancreatitis for which she underwent a subtotal pancreatectomy. Three months later she developed subcutaneous nodules and migratory polyarthralgias. The diagnosis of DFN as the etiology of her arthritis was confirmed by synovial fluid analysis; in addition, magnetic resonance imaging of her long bones revealed multiple marrow infarcts. She was nonambulatory and required assistance with transfers because of severe joint pain. Treatment included local ice, prednisone, methadone, instruction on joint preservation and proper body mechanics, and ambulation with weight-bearing as tolerated with an assistive device. At the patient's discharge, her joint inflammation was clinically improved but not resolved, and she was independent in transfers and ambulation with a walker for short distances. Despite ongoing inflammation, functional improvement was accomplished through a rehabilitation program emphasizing partial weight-bearing ambulation rather than strengthening exercises.

Neuromuscular disease: rehabilitation and electrodiagnosis. 1. Anatomy and physiology of nerve and muscle.

This article of the Self-Directed Physiatric Education Program to assist practitioners and trainees in physical medicine and rehabilitation identifies the anatomy and physiology of nerve, neuromuscular junction, and muscle as they relate to rehabilitation of diseases affecting these structures. Structural relationships of the spinal roots, peripheral nerves, motor units, and muscle fibers are outlined, with structural, functional, and electrodiagnostic correlations. Features of nerve and muscle biochemistry and physiology are reviewed as they relate to common neurological diseases, age, and sex. The spontaneous potentials, motor unit activities, and nerve conduction abnormalities found in diseases of nerve and muscle also are described.

Cosmetic, functional, independent: self-help aids.

Self-help orthotics have been developed to assist functional activities for high-level spinal cord injured patients. The goal of rehabilitation has been to do this with as little intrusion on independence and cosmesis as possible. This paper describes devices to help a patient with C6 quadriplegia independently place his own utensils and eat with an almost normal appearance. The new self-help aids are made from standard silverware, a rivet, and two one-eighth-inch Kydex loops. The loops are riveted centrally on the utensil, allowing for free rotation. The device was evaluated on a patient with C6, complete quadriplegia. The subject demonstrated independence in donning and doffing the device and in eating with an almost normal appearance.

Sensory root level recovery in patients with Frankel A quadriplegia.

This prospective study was designed to demonstrate root level recovery of sensation in the zone of partial preservation in patients with C4 through C8, Frankel A spinal cord injuries. Subjects were evaluated for pin (n = 18) and light touch (n = 17) sensation. All subjects had normal sensation at the level of injury, and decreased or absent sensation at all levels caudal to that level within the zone of partial preservation; they had absent sensation at all levels below the zone of partial preservation. After the initial examination, patients were evaluated weekly for four weeks, and then at 2, 3, 6, 12, 18, and 24 months postinjury. Six of 18 patients recovered pin sensation and five of 17 recovered light touch within three months of injury. Most subjects who recovered had injuries from C5 through C8. Eleven of 12 C4 patients did not recover pin sensation, and 11 of 11 failed to recover light touch. However, five of six C5 to C8 patients recovered both pin and light touch. The p values (Fisher-Exact tests) for the C4 vs C5 to C8 groups were .004 and .001 for pin and light touch, respectively. In conclusion, approximately 30% of the total population improved one sensory root level, with the C5 to C8 injured patients comprising the majority of this improvement.

Overwork-induced axonal hypertrophy in the soleus nerve of the rat.

Effect of overwork, induced by synergistic tenotomy (bilateral tenotomy of the gastrocnemius and the plantaris muscles) of the soleus muscle, was evaluated on areas of the large myelinated axons (LMA) (greater than 19.5 micron 2), in the soleus nerve (the tibial nerve branch innervating the soleus muscle) of the rat. Three lots (n = 12-16) of young adult male (body weight of 275 to 325 g), Sprague-Dawley rats were used. One lot of 16 animals was kept as normal, while the other two underwent bilateral L4 or L5 spinal nerve sectioning. Six to seven animals each from the normal, L4-, and L5 neurectomized animals underwent bilateral synergistic tenotomy of the soleus so that the soleus was retained as the sole plantar-flexor of the ankle joint. The remaining animals were kept as normal or neurectomized control groups. Thus, the six groups studied were normal control (n = 9); normal synergistically tenotomized (n = 7); L4 neurectomized control (n = 8); L4 neurectomized and synergistically tenotomized (n = 6); L5 neurectomized control (n = 8); and L5 neurectomized and synergistically tenotomized (n = 7). Seven days after surgery, the soleus muscles were used to evaluate the muscle weights. The soleus nerves were evaluated for the number plus areas of the LMA by computerized planimetric procedures. The data revealed a 13.9% (p less than 0.05) increase in areas of the LMA in the L5 neurectomized control group; whereas the L5 neurectomized and synergistically tenotomized group showed a 39.6% (p less than 0.01) increase in areas of the LMA.(ABSTRACT TRUNCATED AT 250 WORDS)

Muscle fiber atrophy after cast immobilization in the rat.

The purpose of this study was to evaluate the effect of 6 weeks of bilateral cast immobilization on the adult Wistar rat plantarflexors. Knee and ankle joints were fixed in the neutral position, under sodium pentobarbital anesthesia. Controls (n = 7) and cast-immobilized (n = 7) rats were sacrificed at 6 weeks after the onset of the experimental period. The muscles were evaluated for muscle weight, protein content, and fiber histochemistry. There was equal weight loss in the gastrocnemius, soleus, and plantaris muscles, and greater loss of myofibrillar protein than of sarcoplasmic protein concentrations. Fiber atrophy of types I and II was equal in the soleus, and that of type II was greater than the type I atrophy in both regions of the plantaris. All soleus and 2 plantaris muscles demonstrated fiber damage. The results of this experiment suggest that the degree of fiber atrophy is specific to the fiber type and to its location in different muscles or muscle regions.