Respiratory abdominal muscle recruitment and chest wall motion in myotonic muscular dystrophy.

Abdominal muscles are selectively active in normal subjects during stress and may increase the potential energy for inspiration by reducing the end-expiratory lung volume (EELV). We hypothesized that a similar process would occur in subjects with myotonic muscular dystrophy (MMD), but would be less effective, because of to their weakness and altered chest wall mechanics. Fine-wire electromyography (EMG) of the transversus abdominis (TA), internal oblique (IO), external oblique, and rectus abdominis was recorded in 10 MMD and 10 control subjects. EMG activity, respiratory inductive plethysmography, and gastric pressure were recorded during static pressure measurement and at increasing levels of inspiratory resistance breathing. EELV was reduced and chest wall motion was synchronous only in controls. Although the TA and IO were selectively recruited in both groups, EMG activity of the MMD group was twice that of controls at the same inspiratory pressure. In MMD subjects with mildly reduced forced vital capacity, significant differences can be seen in abdominal muscle recruitment, wall motion, work of breathing, and ventilatory parameters.

Health-related quality of life in peripheral neuropathy.

It is now possible for the clinician to use multidimensional measures to assess the quality of life of their patients. Some of the more widely used instruments to measure HRQOL are the Medical Outcomes Study Short Form 36, the Nottingham Health Profile, the Sickness Impact Profile, and the World Health Organization Quality of Life instrument. Potential uses of quality of life assessment tools include: (1) monitoring the health and social status of a given population, (2) evaluating health care policy, (3) conducting clinical trials, (4) assessing the effectiveness of rehabilitation services, (5) justifying the allocation of limited social and health care resources, and (6) tailoring management to the needs of the patient.

Magnetic resonance imaging of denervated muscle: comparison to electromyography.

The purpose of the study is to further assess the usefulness of short TI (time to inversion) recovery (STIR) magnetic resonance imaging (MRI) in detecting denervation of skeletal muscle compared to needle electromyography (EMG). Ninety subjects with clinical evidence of peripheral nerve injury or radiculopathy underwent STIR MRI and EMG of the affected limb. In 74 (82%) of these subjects, a positive correlation was found between STIR MRI and EMG (P < 0.009). STIR MRI has a relative sensitivity of 84% and specificity of 100% for detecting denervation. A subset of 28 subjects underwent quantitative assessments of signal intensity ratio (SIR) from the STIR MRI. The rank order correlation coefficient between the SIR and abnormal spontaneous activity on EMG was 0.70 (P < 0.001). Increased signal intensity on STIR MRI corresponds closely with spontaneous activity on EMG in denervated muscle. Although less sensitive than EMG in detecting muscle denervation, STIR MRI may be a useful adjunctive diagnostic tool in this setting.

Pursed lips breathing improves ventilation in myotonic muscular dystrophy.

OBJECTIVE: To determine the effects of pursed lips breathing on ventilation, chest wall mechanics, and abdominal muscle recruitment in myotonic muscular dystrophy (MMD). DESIGN: Before-after trial. SETTING: University hospital pulmonary function laboratory. PARTICIPANTS: Eleven subjects with MMD and 13 normal controls. INTERVENTION: Pursed lips breathing. OUTCOME MEASURES: Electromyographic (EMG) activity of the transversus abdominis, external oblique, internal oblique, and rectus abdominis was recorded with simultaneous measures of gastric pressure, abdominal plethysmography, and oxygen saturation. Self-reported sensations of dyspnea, respiratory effort, and fatigue were recorded at the end of each trial. RESULTS: Pursed lips breathing and deep breathing led to increased tidal volume, increased minute ventilation, increased oxygen saturation, reduced respiratory rate, and reduced endexpiratory lung volume. Dyspnea, respiratory effort, and fatigue increased slightly with pursed lips breathing. EMG activity of the transversus abdominis and internal oblique muscles increased in MMD only and was associated with an increase in gastric pressure. CONCLUSIONS: Pursed lips breathing and deep breathing are effective and easily employed strategies that significantly improve tidal volume and oxygen saturation in subjects with MMD. Abdominal muscle recruitment does not explain the ventilatory improvements, but reduced end-expiratory lung volume may increase the elastic recoil of the chest wall. Further clinical studies are needed to ascertain if the ventilatory improvements with pursed lips breathing and deep breathing improve pulmonary outcomes in MMD.

Expanding the role of hospice care in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive, ultimately fatal, motor neuron disease that poses a myriad of clinical and end-of-life problems. The needs of advanced ALS patients are well suited to the interdisciplinary, multi-modality setting of hospice, where comprehensive palliative strategies may ease suffering and allow the patient to die with dignity in the home. Unfortunately, hospice services are far underutilized in this setting. There is a great need to increase awareness of both patients and clinicians regarding the effectiveness of hospice in the care of advanced ALS patients.

Neuropathic pain in Charcot-Marie-Tooth disease.

OBJECTIVES: To determine the frequency and extent to which subjects with Charcot-Marie-Tooth (CMT) disease report pain and to compare qualities of pain in CMT to other painful neuropathic conditions. STUDY DESIGN: Descriptive, nonexperimental survey, using a previously validated measurement tool, the Neuropathic Pain Scale (NPS). PARTICIPANTS: Participants were recruited from the membership roster of a worldwide CMT support organization. MAIN OUTCOME MEASURES: NPS pain descriptors reported in CMT were compared with those reported by subjects with postherpetic neuralgia (PHN), complex regional pain syndrome, type 1 (CRPS-1), also known as reflex sympathetic dystrophy, diabetic neuropathy (DN), and peripheral nerve injury (PNI). RESULTS: Of 617 CMT subjects (40% response rate), 440 (71%) reported pain. with the most severe pain sites noted as low back (70%), knees (53%), ankles (50%), toes (46%), and feet (44%). Of this group, 171 (39%) reported interruption of activities of daily living by pain; 168 (38%) used non-narcotic pain medication and 113 (23%) used narcotics and/or benzodiazepines for pain. The use of pain description was similar for CMT, PHN, CRPS-1, DN, and PNI in terms of intensity and the descriptors hot, dull, and deep. CONCLUSIONS: Neuropathic pain is a significant problem for many people with CMT. The frequency and intensity of pain reported in CMT is comparable in many ways to PHN, CRPS-1, DN. and PNI. Further studies are needed to examine possible pain generators and pharmacologic and rehabilitative modalities to treat pain in CMT.

The effect of age and temperature on mdx muscle fatigue.

We have studied the in vitro contractile and fatigue characteristics of extensor digitorum longus (EDL) muscles from 8- and 62-week-old dystrophin-deficient (mdx) and control mice at 20 degrees C and 35 degrees C. There were no differences in fatigability at 20 degrees C, but at 35 degrees C the dystrophin-deficient muscles demonstrated increased fatigability compared to controls, with the older mice exhibiting the greatest fatigue. These results suggest a temperature-related mechanism of myofibrillar fatigue in dystrophin-deficient EDL muscles.

Effects of aging and voluntary exercise on the function of dystrophic muscle from mdx mice.

To understand how exercise affects the contractile function of dystrophic muscle, we examined the effect of long-term voluntary exercise on mdx mice and related these effects to our findings in sedentary aging mice. Although the mdx mouse is the genetic homolog for Duchenne muscular dystrophy, it does not demonstrate the same progression in limb muscle dysfunction as Duchenne muscular dystrophy as it ages. We postulated that the sedentary lifestyle of this animal plays an important role in its minimal phenotypic expression. To examine the effect of exercise, eight C57BL/10 (C57) and eight mdx mice were allowed to run ad libitum for one year. Forty sedentary mdx mice and 40 sedentary C57 from one month to 18 months of age were used as controls. Contractile characteristics of the extensor digitorum longus and soleus muscles and morphometric characteristics of the mice were examined. The mdx mice ran approximately 45% fewer kilometers per day than C57 mice. Long-term voluntary running had beneficial training effects on both the old mdx mice and their C57 controls. The exercise ameliorated the age-associated loss in tension production that was observed in the soleus of sedentary mdx and sedentary C57 mice. There was a 9% reduction in the fatigability of the extensor digitorum longus muscle of the old mdx mice after the exercise. Despite these improvements, the old mdx mice exhibited significant functional deficits compared with their C57 controls. Our hypothesis, that long-term voluntary exercise would have a beneficial training effect on control mice and a deleterious effect on mdx mice as they aged, was not supported by this study. This study shows that dystrophin-less muscles from sedentary mice display significant signs of muscle damage, yet can respond beneficially to low-level voluntary running in a manner similar to that of the C57 control.

Quality of life. Issues for persons with neuromuscular diseases.

Improving quality of life has always been a goal of rehabilitation medicine. However, health care providers often do not know much about the quality of life of individuals with neuromuscular diseases, nor what factors are critical to achieving a good quality of life. Lack of knowledge about subjective quality of life factors can negatively influence expectations and selection of treatments. In the most glaring cases, a physician's subjective but incorrect assessment of a disabled individuals' quality of life may prevent life-sustaining interventions. As a group, the quality of life of individuals with NMD is not much different than nondisabled controls and is substantially better than presumed by the general public and, often times, by health care workers. Nevertheless, their quality of life is reduced in certain areas. Surprisingly, level of disability is not a critical factor that significantly alters life satisfaction. Presumably, this is because physical functioning has been adequately managed. The greatest problems that individuals with neuromuscular disease identified were: lack of information about the disease and services; poor coordination of services; negative attitudes; and a diminished expectation of their potential. In addition, people with severe disabilities had significant problems obtaining, financing, and managing personal care attendants. Factors related to a good quality of life were related to perceived control, perceived health status, but not disability. The more that people could do for themselves, either on their own or with personal care assistants, assistive devices, and use of technology, the better their quality of life.

Animal models of neuromuscular diseases: pathophysiology and implications for rehabilitation.

This article explains how animal models can be utilized to develop rehabilitation approaches to minimize the pathophysiology of neuromuscular diseases (NMD). Homologous animal models can be used to understand the pathogenesis of each NMD and the effect of physical interventions. Much of the current work using animals has been conducted to show how gene therapy could be used to ameliorate these diseases. Although we applaud this work, animal models should also be used to determine how the phenotypic expression of the disease can be modified by such physical interventions as exercise, stretching, and immobilization. Methods that can be experimentally applied to animals but not to humans can be used to determine the underlying causes of the pathologic process and to identify potential therapies for NMD.

Employment profiles in neuromuscular diseases.

Consumer and rehabilitation provider factors that might limit employment opportunities for 154 individuals with six slowly progressive neuromuscular diseases (NMD) were investigated. The NMDs were spinal muscular atrophy (SMA), hereditary motor sensory neuropathy (HMSN), Becker's muscular dystrophy (BMD), facioscapulohumeral muscular dystrophy (FSHD), myotonic muscular dystrophy (MMD), and limb-girdle syndrome (LGS). Forty percent were employed in the competitive labor market at the time of the study, 50% had been employed in the past, and 10% had never been employed. The major consumer barrier to employment was education. Other important factors were type of occupation, intellectual capacity, psychosocial adjustment, and the belief by most individuals that their physical disability was the only or major barrier to obtaining a job. Psychological characteristics were associated with level of unemployment. However, physical impairment and disability were not associated with level of unemployment. There also were differences among the types of NMDs. Compared with the SMA, HMSN, BMD, and FSHD groups, the MMD and LGS groups had significantly higher levels of unemployment, lower educational levels, and fewer employed professional, management, and technical workers. Nonphysical impairment factors such as a low percentage of college graduates, impaired intellectual function in some individuals, and poor psychological adjustment were correlated with higher unemployment levels in the MMD group. Unemployment in the LGS group was correlated with a failure to complete high school. Major provider barriers to employment were the low level of referrals to Department of Rehabilitation by physicians and the low percentage of acceptance into the State Department of Rehabilitation. The low rate of acceptance was primarily attributable to the low number of referrals compounded by a lack of counselor experience with individuals with NMD. Both consumer and provider barriers may contribute to the lack of interest in obtaining a job.

Profiles of neuromuscular diseases. Myotonic dystrophy.

Ninety-two individuals with myotonic dystrophy (MD) were evaluated prospectively over a 10-yr period and separated into two types, 75 noncongenital (NC-MD) and 17 congenital (C-MD) MD. Muscle weakness was relatively mild and similar in both types, 4.0 +/- 0.7 manual muscle test (MMT) scores for NC-MD and 3.8 +/- 0.7 in C-MD. However, weakness was progressive in the former, -0.36 MMT units per decade, and nonprogressive in C-MD. Weakness was usually generalized in both types, with no significant differences between upper and lower extremities or the proximal and distal muscles. Flexor and extensor differences were variable. Quantitative strength measurements showed a similar pattern but were more sensitive showing marked strength losses of 40-50% in muscle groups with MMT scores of four or more. There was a high frequency (47%) of relatively mild, nonprogressive scoliosis in C-MD, whereas spine deformity was unusual in NC-MD. Contractures, usually at the ankles, were also more common in C-MD. In NC-MD and C-MD, respectively, there was a low frequency of severe restrictive lung disease (14 and 20%) but a high percentage of significant electrocardiographic (ECG) abnormalities (75 and 81%), including conduction defects. There was a marked difference between the two types of MD in intellectual and cognitive function. Seventy-five percent of C-MD subjects showed impairment, frequently severe, compared with 35% impairment, usually mild, for NC-MD individuals. Functional evaluation was not markedly affected, but timed motor performance showed significant disability especially for individuals with C-MD.

Profiles of neuromuscular diseases. Facioscapulohumeral muscular dystrophy.

Data were collected prospectively over a 10-yr period from 53 subjects with facioscapulohumeral muscular dystrophy (FSHD) to provide a profile of impairment and disability. Manual muscle testing (MMT) indicated greater involvement of proximal musculature, although a subgroup demonstrated early weakness of the ankle dorsiflexors. Asymmetry of upper extremity musculature was noted, with greater weakness of selected dominant limb muscle groups. Weakness, in general, was relatively mild, with an overall mean MMT score of 3.7 units. The rate of strength loss was quite slowly progressive, a decline of only -0.22 MMT units per decade of age. An early age of onset was associated with greater likelihood of more severe and progressive weakness. Isometric and isokinetic quantitative strength testing revealed that all muscle groups were 36-68% weaker than a control population. Although nearly 50% of the subjects had vital capacity evidence of restrictive lung disease, only 13% had severe involvement, and only 22% had a history of pulmonary complications. There was no age or disease duration effect on pulmonary function measurements or complications. As with the other neuromuscular diseases, maximal expiratory pressure measurements were more sensitive than other pulmonary function tests. Abnormal electrocardiogram findings were rare and minor and not related to overt cardiac disease. Contractures were rare and mild. Thirty-five percent of the patients had spine deformity; however, most had hyperlordosis. Intellectual function was normal, and there were few abnormalities on personality tests. Functional testing demonstrated wide variation in disability with FSHD, but motor weakness uniformly translated into impaired motor performance skills. This profile demonstrates the clinical heterogeneity of FSHD.

Profiles of neuromuscular diseases. Spinal muscular atrophy.

Forty-five individuals with spinal muscular atrophy (SMA) types II and III were evaluated prospectively over a 10-yr period to develop an impairment and disability profile. SMA II subjects showed marked weakness and progressive decline of strength. Mean manual muscle test (MMT) score for all muscles combined was 2.3 +/- 0.6, with a decline in strength of -0.24 MMT units per decade. SMA III individuals had a relatively static or very slowly progressive course and were far stronger. Mean MMT score for all muscles combined was 3.8 +/- 0.7, and the decline in strength per decade was not significant. In both types proximal weakness was greater than distal, but there was greater involvement of the lower extremities and the extensor muscle groups only in SMA II. Contractures, progressive scoliosis, and restrictive lung disease (RLD) were present in most of the SMA II individuals, but these complications were rare in SMA III. Maximal expiratory pressures were affected earlier and to a greater degree than vital capacity. Seventy-eight percent of those with SMA II had scoliosis with a mean Cobb angle of the primary curve of 62 +/- 37 degrees. Forty-one percent had severe RLD, and 17% had moderate RLD. In both types, 63% had abnormal electrocardiograms although most had minor findings. Timed motor performance and functional evaluations indicated that muscle weakness translated to substantial disability in both SMA II and III, with more severe impairment noted in SMA II. Neither type was associated with abnormal means scores on intellectual and neuropsychologic test batteries.

Profiles of neuromuscular diseases. Design of the protocol.

The purpose of this 10-yr investigation was to develop comprehensive impairment and disability profiles of the clinical characteristics of seven neuromuscular diseases: spinal muscular atrophy, hereditary motor sensory neuropathy, Duchenne muscular dystrophy, Becker's muscular dystrophy, facioscapulohumeral muscular dystrophy, limb-girdle syndrome, and myotonic dystrophy. Based on the World Health Organization's classification of disablement, as applied to neuromuscular diseases, impairment was evaluated by measurements of strength, range of motion, spine deformity, cardiac and pulmonary function, and intellectual capacity. Disability was evaluated by measures of mobility and upper extremity function, cardiopulmonary adaptations, cardiac and pulmonary complications, and psychosocial adjustment.

Profiles of neuromuscular diseases. Limb-girdle syndromes.

Sixty-six individuals with Limb-Girdle Syndrome (LGS) were evaluated over a 10-yr period and classified into three types: 19 severe autosomal recessive muscular dystrophy of childhood (ARMDC), alternatively referred to by some as SCARMD, 18 autosomal dominant late onset (ADLO), and 29 pelvifemoral (PF) individuals. ARMDC subjects showed the greatest weakness, 2.5 +/- 1.0, mean Manual Muscle Test (MMT) grade for all muscles combined, and the only significant progression of loss of strength, -0.59 MMT unit decline per decade. Strength loss in ADLO and PF types was about the same, 3.7 +/- 0.7 and 4.0 +/- 0.7 grades, respectively. Quantitative strength measurements in ADLO and PF types were more sensitive than MMTs, showing losses of 30-40% strength in muscle groups with MMT grades of 4 or higher. All three types showed greater proximal and lower extremity weakness but usually no difference between flexor and extensor strength. There was a high percentage (44%) of mild very slowly progressive scoliosis in ARMDC, but spine deformity was unusual in ADLO and PF (11%) LGS. Contractures were few, slowly progressive, and usually mild in severity in all types, although more frequent in ARMDC. There also was a low frequency of severe restrictive lung disease in all types (10%) but a high percentage of electrocardiogram abnormalities (62-73%). The most common electrocardiogram abnormalities were increased R/S ratio in V1 and infranodal conduction defects. Intellectual and cognitive functions were within normal limits. Mobility and extremity function reflected the strength differences between the ARMDC and other types of LGS. Eight-five percent of ARMDC individuals relied on a wheelchair for all or part of their mobility, and all were unable to complete timed motor performance tests within the 99th percentile range for controls.

Profiles of neuromuscular diseases. Hereditary motor and sensory neuropathy, types I and II.

Data were collected prospectively for an impairment and disability profile for 86 hereditary motor and sensory neuropathy, types I and II (HMSN) subjects over a 10-yr period. Our data confirm that HMSN is a slowly progressive disorder that has a very heterogeneous phenotypical expression. The disorder was characterized primarily by diffuse muscle weakness with prominent distal atrophy. The mean manual muscle test (MMT) strength grade for all muscle groups combined was 3.9 +/- 0.7 MMT units. There was a slowly progressive decline in strength, only -0.15 MMT units per decade. Distal muscle groups were weaker than proximal muscles, and the decline in strength of the ankle muscles was greater than for the proximal muscles. There was no side dominance. Anthropometric data revealed that distal atrophy may be masked by subcutaneous fat in female subjects. On average, HMSN subjects produced 20-40% less force than normal controls, using quantitative isometric and isokinetic strength measures, even when MMT scores were normal. Pulmonary and cardiac abnormalities were uncommon, as were spine deformity and joint contractures. Only 1 individual had severe restrictive lung disease, and 12 (14%) had a history of significant respiratory complications with no age or disease duration effect. As with the other neuromuscular diseases, maximum expiratory pressure was more affected than forced vital capacity. Fourteen individuals (30%) had abnormal electrocardiograms, and six (7%) had a history of significant cardiovascular complications with no age or disease duration effect. Kyphosis was the major spine deformity. Cardiopulmonary responses to exercise testing were markedly abnormal, showing reduced aerobic capacity. Functional evaluations and timed motor performance tests showed only mild disability in most individuals. With timed motor performance testing muscle weakness translated to impaired motor performance skills. Overall, mean scores on intellectual function and neuropsychologic profiles were normal.

Profiles of neuromuscular diseases. Becker's muscular dystrophy.

Fifteen subjects with Becker's muscular dystrophy (BMD) were studied prospectively over a 10-yr period to provide a profile of impairment and disability. Proximal lower extremity musculature (particularly the hip and knee extensors), ankle dorsiflexors, and neck flexors showed significantly early weakness. Extensor muscle groups were weaker than flexor muscles at the elbow and knee. The mean manual muscle test (MMT) strength grade for all muscle groups combined was 3.7 +/- 0.8 MMT units. There was a slowly progressive decline in strength, only -0.31 MMT units per decade, and the decline was relatively equal in all muscle groups. There was not side dominance. Severe contractures did not appear to be a problem until after transition to a wheelchair, and scoliosis was rare. Restrictive lung disease occurred as a late complication in a small percentage of cases; however, maximal expiratory pressure was significantly reduced early in the disease. Only two individuals (19%) had severe restrictive lung disease and a history of significant respiratory complications. There was a slight but significant decline in forced vital capacity and maximal expiratory pressure with age and disease duration. The cardiomyopathy in BMD appeared to be disproportionately severe in some cases. Eleven individuals (73%) had abnormal electrocardiograms, and five (25%) had a history of significant cardiovascular complication, with no age or disease duration effect. Functional evaluations and timed motor performance tests showed only mild disability in most individuals. Mean intellectual and neuropsychologic function was within normal limits, but with a large variability in intelligence quotient scores. This report and others suggest a tremendous heterogeneity of severity among males with BMD.

Profiles of neuromuscular diseases. Duchenne muscular dystrophy.

One hundred and sixty-two patients with Duchenne muscular dystrophy (DMD) were followed over a 10-yr period to provide a profile of impairment and disability. The median height and weight of DMD boys were normally distributed before ages 9-10, but during the second decade height was markedly reduced, and weight was no longer normally distributed. Younger boys gained more weight than normals, whereas older individuals actually showed weight loss. Manual muscle test (MMT) measurements showed loss of strength in a fairly linear fashion from ages 5-13 yr, -0.25 MMT units per year. Upper extremity muscles were stronger than lower extremity muscles, proximal muscle groups were weaker than distal muscle groups, and extensor muscles were weaker than flexor muscles. There was no side dominance. There was a change in the rate of strength loss at 14-15 yr, and the decline slowed to only -0.06 MMT units per year. Although MMT and quantitative strength measurement profiles were similar, the latter were far more sensitive. In general, by the time strength declined to MMT grade 4, isometrically measured strength was 40-50% of normal control values. Joint contractures were rare before age 9, increased in frequency and severity with age, and were present in most individuals older than 13. Lower extremity contractures were strongly related to onset of wheelchair reliance, but there was no association between muscle imbalance around a joint. The prevalence of scoliosis increased between ages 11 and 16, with about 50% of the boys acquiring scoliosis between ages 12 and 15, corresponding to the onset of the adolescent growth spurt. Wheelchair reliance and scoliosis were both age-related. Percent predicted forced vital capacity declined at different yearly rates: ages 7-10, -0.3%; ages 10-20, -8.5%; after age 20, -6.2%. There was a direct relationship between percent predicted FVC and MMT scores. Decreased airway pressures, especially maximal expiratory pressure, appeared earlier than reductions in FVC but followed the same pattern. Thirty percent of the DMD boys had a history of respiratory complications, and the frequency increased with age. Spine deformity did not have a significant additive effect on the age-related decrement in pulmonary function. There was a high occurrence (79%) of abnormal electrocardiograms with age-related progression of some abnormalities, but only 30% of the patients had a history of cardiovascular complications. Functional level grades and timed motor performance measurements had a nonlinear relationship with strength and age.(ABSTRACT TRUNCATED AT 400 WORDS)