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The relationship between anaerobic lactate threshold and plasma catecholamines during incremental exercise in hereditary spastic paraplegia.

Lower limb muscle chronic hyperactivity in hereditary spastic paraplegia (HSP) is the consequence of motor corticospinal tract involvement, which in turn has been hypothesized to be of mitochondrial origin. In order to assess skeletal muscle aerobic metabolism and sympathetic response during exercise in 10 HSP patients, we evaluated their blood lactate and catecholamine levels during an incremental workload bicycle exercise. Lactate, but not epinephrine or norepinephrine, levels were significantly higher in the HSP patients than in control subjects, in both resting conditions and during exercise. In the patients, the anaerobic lactate threshold was reached prematurely (at 50% of the predicted normal maximal power output) when compared to normal controls. This finding was not related to any specific muscle morphology or histochemical activity. Although other factors, including chronic spasticity and muscle deconditioning, have to be considered in the interpretation of our data, our results suggest the possible involvement of a mitochondrial mechanism, independently of sympathetic system overactivation, in exercising skeletal muscle of HSP patients.

Adult↗

[Familial spastic paraplegia with syndrome of continuous muscle fiber activity (Isaacs)].

A woman aged fifty-three developed paraparesis at the age of 4, which progressed slowly and required crutches by the age of 30. At the age of 51, muscle stiffness involved bilateral hands and arms gradually. At the age of 53, she suffered from painful spasms in right deltoid muscle. Her two brothers had spastic paraplegia without other neurological deficits. Her paternal grandfather and maternal grandmother were cousins. Slight dementia was noted (WAIS: IQ, 79). Her posture was stiff and muscles of upper limbs were in a persistent contraction; Subcutaneous tissue was thin, and muscles were well-defined and firm. There was moderate muscle weakness of legs and hands. Continuous fasciculations and myokymias were recognized in muscles of the arms and the limb girdles. Muscle tone was considerably increased especially in the bilateral arms. The deep tendon reflexes were exaggerated with extensor plantar responses. Profuse sweating affected palms, soles and backs. No sensory disturbance was appreciated. There was no myotonic responses to percussion of muscles. Following laboratory data were normal; thyroid functions, CSF studies, anti HTLV-I antibody and long chain fatty acid in red blood cells, myelography and brain CT except for increased basal metabolic rate (53%). Electromyographic study in the arms and hands revealed spontaneous motor unit activities including doublets at rest and increased proportion of polyphasic potentials and high amplitude potentials in voluntary contraction. Biopsy of right quadriceps femoris muscle showed hypertrophy of type I fibers and angulated atrophy of type II fibers. Continuous muscle activities in upper limbs did not change at sleep or with intravenous administration of 7 mg diazepam.(ABSTRACT TRUNCATED AT 250 WORDS)

Electromyography↗

Improving calf muscle strength in patients with spastic equinovarus deformity by transfer of the long toe flexors to the Os calcis.

The split tibialis anterior tendon transfer (SPLATT), Achilles tendon lengthening, and toe flexor release are proven and effective procedures for correcting a spastic equinovarus deformity of the foot. Paresis is a prominent feature of upper motoneuron syndrome. Lengthening the Achilles tendon, although necessary to correct the equinus, further weakens the gastrocnemius-soleus muscle group. The calf paresis commonly results in the need for an ankle-foot orthosis (AFO) during ambulation. Previous studies have shown that despite the correction of the equinovarus deformity, only one third of patients were able to ambulate without an AFO. The need for continued use of an AFO was because of insufficient calf strength to stabilize the tibia during late stance when the body mass is anterior to the ankle joint. This study prospectively evaluated the results of transfer of the flexor hallucis longus (FHL) and flexor digitorum longus (FDL) to the os calcis in 30 patients. The transfer was done in an effort to augment the strength of the gastrocnemius-soleus muscle complex. Twenty-five patients in group I (the control group) underwent SPLATT, Achilles tendon lengthening, and toe flexor release. Thirty patients in group II (the study group) underwent the identical procedures plus the additional FHL and FDL transfer to the os calcis. Postoperatively, the varus and toe flexion deformities were corrected in all feet. In group II, two feet had a mild residual equinus that did not interfere with ambulation. Of the 11 patients who were not independent community ambulators in group I, 7 (64%) improved ambulatory status by at least one level after surgery. Of the 15 patients who were not independent community ambulators in group II, 14 (93%) improved ambulatory status by at least one level after surgery. In group I, 10 of 25 (40%) of the patients were brace free at follow-up. In group II, 21 of 30 (70%) were brace free at follow-up (c2, P =.025). These results indicate that the addition of an FHL and FDL transfer to the os calcis at the time of SPLATT, Achilles tendon lengthening, and toe flexor release improves calf strength and allows greater increase in function and less reliance on orthotics.

Achilles Tendon↗

Prevalence of spasticity post stroke.

OBJECTIVES: To establish the prevalence of spasticity 12 months after stroke and examine its relationship with functional ability. DESIGN: A cohort study of prevalence of spasticity at 12 months post stroke. SETTING: Initially hospitalized but subsequently community-dwelling stroke survivors in Liverpool, UK. SUBJECTS: One hundred and six consecutively presenting stroke patients surviving to 12 months. MAIN OUTCOME MEASURES: Muscle tone measured at the elbow using the Modified Ashworth Scale and at several joints, in the arms and legs, using the Tone Assessment Scale; functional ability using the modified Barthel Index. RESULTS: Increased muscle tone (spasticity) was present in 29 (27%) and 38 (36%) of the 106 patients when measured using the Modified Ashworth Scale and Tone Assessment Scale respectively. Combining the results from both scales produced a prevalence of 40 (38%). Those with spasticity had significantly lower Barthel scores at 12 months (p < 0.0001). CONCLUSION: When estimating the prevalence of spasticity it is essential to assess both arms and legs, using both scales. Despite measuring tone at several joints, spasticity was demonstrated in only 40 (38%) patients, lower than previous estimates.

Aged↗

Concept of spastic hypertonia.

This introductory article highlights the definition of spastic hypertonia, and briefly introduces the reader to the incidence and most frequent causes of spastic hypertonia. The article also discusses the functional losses caused by spastic hypertonia that will be reviewed more thoroughly in the following articles. Also discussed is the neural physiology and the locations of the structural lesions within the central nervous system that are involved in spastic hypertonia, with an emphasis on the different clinical presentations depending on the location of the lesion.

Humans↗

Intraoperative monitoring during selective posterior rhizotomy: technique and patient outcome.

We evaluated intraoperative electromyographic (EMG) results among 110 pediatric patients with spastic cerebral palsy who underwent selective posterior rhizotomy. We analyzed surgical outcomes for 60 of these patients who returned for follow-up assessment between 4 and 17 months postoperatively. Reduction in muscle tone (resistance to passive movement), increased range of motion and improvements in functional skills were seen at follow-up. To control for possible changes due to development, participation in therapy, or instability of measurements, 30 rhizotomy patients were evaluated twice during a baseline period of several months prior to surgery. No significant changes were found between these two measurement sessions during the baseline control period suggesting that the rhizotomy surgery itself caused the postoperative improvements. These intraoperative EMG monitoring techniques have been adopted at many other centers but variations in specific methods and EMG criteria have developed subsequently among major hospitals where selective posterior rhizotomy is performed. These variations in neurophysiologic methods and recent controversy about the usefulness of such intraoperative EMG monitoring created a need for us to publish our standard EMG selection technique. We describe here, in detail, methods for nerve rootlet testing and selection.

Cerebral Palsy↗

Initial motor unit recruitment in patients with spastic hemiplegia.

Lesions of the first motor neuron provoke abnormal voluntary movements. To clarify the central nervous system mechanisms underlying these changes we analyzed the behavior of the first motor unit recruited during a minimal effort tonic contraction of the deltoid and abductor digiti minimi manus muscles in patients with hemiplegia due to cerebrovascular lesions in the distribution of the middle cerebral artery. We compared data from paretic and healthy muscles in the same subject. The onset and recruitment intervals determined for the single motor unit yielded the range of control. The first recruited motor unit had a lower baseline firing rate and the second recruited motor unit potential appeared significantly earlier (p < 0.01) in plegic than in healthy muscles. Both changes affected distal more than proximal locations. Recordings from plegic muscles, particularly at distal locations, also disclosed a lowered range of control. These findings suggest that in hemiplegic patients the central nervous system loses its ability to modulate the frequency of firing during minimal effort voluntary movements so that distal muscles tend to behave like proximal muscles.

Aged↗

Objective measurement of muscle strength in children with spastic diplegia after selective dorsal rhizotomy.

OBJECTIVES: To examine changes in isometric muscle strength at the elbow, knee, and ankle at 6 months and 1 year after selective dorsal rhizotomy (SDR) and to determine if SDR altered the frequency of muscle cocontraction. DESIGN: Prospective outcome study of a consecutive sample. SETTING: Children's hospital. PATIENTS: Ten children with spastic diplegia (7 independent and 3 dependent ambulators who used assistive devices) and 8 age-matched controls. INTERVENTIONS: SDR; physical and occupational therapy; elbow, knee, and ankle measured for flexion and extension strength during three 10-second isometric contractions for each muscle group; and monitored cocontraction measured via muscle electrodes. MAIN OUTCOME MEASURES: Absolute and normalized values of isometric strength; and alterations in the frequency of cocontraction at 6 months and 1 year postoperatively. RESULTS: Children with spastic diplegia showed significantly weaker knee extensors, ankle dorsiflexors, and ankle plantarflexors than age-matched controls. There were no significant differences in strength between the 2 groups in the elbow flexors, elbow extensors, and knee flexors. Isometric strength did not increase or decrease significantly after SDR. Cocontraction during knee extension was normalized after SDR, whereas cocontraction during ankle plantarflexion was unchanged by SDR in the majority of children. CONCLUSION: SDR did not result in a significant decrease in muscle strength in ambulatory children with spastic diplegia. The normalization of the electromyographic patterns at the knee and not the ankle after SDR lends support to the premise that in children with cerebral palsy cocontraction is multifaceted, representing a volitional strategy to enhance control, as well as a disorder of the mechanisms that govern patterns of muscle activity.

Cerebral Palsy↗

Residual spasticity after selective posterior rhizotomy.

The technique used in performing selective posterior rhizotomies to treat spastic cerebral palsy remains controversial. One hundred nine children who had undergone selective posterior rhizotomies were studied 6 months after their surgery. Their residual spasticity was correlated to the number of roots and whether or not abnormally responding roots were left, in order to validate the surgical technique used to treat spastic cerebral palsy at most neurosurgical centers in North America. The children were divided into three groups (group A: children who had their L2-S1 roots tested and selectively lesioned, n = 15; group B: children who had their L2-S2 roots tested and selectively lesioned, n = 62; group C: children who had their L2-S2 roots tested and whose lesioning was directed both by the response to the stimulation and mapping of the S1-S3 dorsal roots for afferent pudendal nerve activity, n = 32). Clinically significant residual spasticity was present in the gastrocnemius in 33% of the group A children, 11% of the group B children, and 6% of the group C children. We found that there was no significant increase in residual spasticity in the group C children when abnormally responding roots were not cut in order to preserve pudendal nerve activity. This study shows that the inclusion of the S2 roots decreases the amount of residual spasticity (P < 0.01). It also shows that leaving abnormally responding S2 roots to preserve pudendal nerve activity does not affect the incidence of postoperative spasticity (P > 0.1).

Adolescent↗

[Epidemiology of pes varus and/or equinus one year after a first cerebral hemisphere stroke: apropos of a cohort of 86 patients].

OBJECTIVE: To determine the frequency and the functional consequences of varus equinus in stabilized vascular hemiplegia. METHODS: Prospective cohort study of 86 hemiplegic patients. All patients consecutively admitted for a first hemispheral stroke between July 2001 and January 2002 were included. The evaluation consisted in a clinical examination and a descriptive study of gait. The functional capacity of patients with and without varus equinus were compared using the Barthel index, the New Functional Ambulation Classification (NFAC), the confortable ten meters gait speed and gait perimeter. RESULTS: The incidence of varus equinus was 18%. There was no difference in gait speed (0.8 m/s), NFAC or Barthel index between patients with or without varus equinus. Patients with varus equinus had had more specialized, intensive and prolonged rehabilitation. The only prognostic factor that could be identified was the motor impairment and the existence of spasticity. DISCUSSION: The mechanism of varus equinus is thought to be mainly the over-activity of gastrocnemius and solaris compared to that of the tibialis anterior, associated to the weakness of fibular muscles. The role of tibialis posterior is thought to be less important. The frequency of varus equinus after a first hemispheral stroke was low and the consequences were limited. This could be in part explained by the access of these patients to early, specialized and prolonged rehabilitation care.

Aged↗

Management of spasticity in adults: practical application of botulinum toxin.

Spasticity, characterized by increased muscle tone, exaggerated stretch reflexes, and abnormal limb posture, is a common sequel of central nervous system pathology. Historically, medicinal treatments have been of limited efficacy. This review discusses the clinical features of spasticity, the functional and pathological consequences, and treatment. It reviews the most common patterns of spasticity encountered in the upper and lower limbs and focuses on focal treatment of spastic muscles with the three commercially available botulinum toxins Botox, Dysport, and Myobloc/NeuroBloc. It addresses practical details such as muscle selection and identification, drug dilution, and doses.

Anti-Dyskinesia Agents↗

Electromyographic studies in calves with spastic paresis.

As part of the investigation into the cause of spastic paresis in cattle, electromyographic studies were done in a number of calves with spastic paresis of one limb and in a number of normal calves. The calves with spastic paresis were also studied at various intervals after total neurectomy of the tibial nerve or tenotomy of the Achilles tendon structure. A marked increase in activity was perceptible in a number of muscles but characteristic changes in the EMG were not observed.

Achilles Tendon↗

Beyond Ashworth. Electrophysiologic quantification of spasticity.

Spasticity is a hallmark of upper motor neuron lesion, which is easily identified but is difficult to quantify and treat. The Ashworth scale lacks reliability. Available biomechanical and electrophysiologic studies offer a more reliable measure of spastic hypertonia but have limited clinical utility. A uniformly acceptable, reliable, and practical measure of spasticity continues to elude the clinician. This chapter reviews the basic neuroanatomy and physiology of the stretch reflex and the pathophysiology of the spasticity. Current biomechanical and electrophysiological techniques are used to quantify spasticity.

Afferent Pathways↗