Daytime predictors of sleep disordered breathing in children and adolescents with neuromuscular disorders

Sleep disordered breathing with or without nocturnal hypercapnic hypoventilation is a common complication of respiratory muscle weakness in childhood neuromuscular disorders. Nocturnal hypercapnic hypoventilation as a sign of respiratory muscle fatigue, portends a particularly poor prognosis. We aimed at identifying daytime predictors of sleep disordered breathing at its onset and sleep disordered breathing with nocturnal hypercapnic hypoventilation. Forty-nine children and adolescents (11.3+/-4.4 years) with progressive neuromuscular disorders were studied with inspiratory vital capacity, peak inspiratory pressure, arterial blood gases, polysomnography, and a ten-item symptoms questionnaire. Daytime respiratory function was prospectively compared with polysomnographic variables. Sleep disordered breathing was found in 35/49 patients (71%). Twenty-four (49%) had sleep disordered breathing with nocturnal hypercapnic hypoventilation. Inspiratory vital capacity and peak inspiratory pressure, but not symptom score, correlated with sleep disordered breathing and severity of nocturnal hypercapnic hypoventilation. Sleep disordered breathing-onset was predicted by inspiratory vital capacity<60% (sens. 97%, spec. 87%). Sleep disordered breathing with nocturnal hypercapnic hypoventilation was predicted by inspiratory vital capacity<40% (sens. 96%, spec. 88%) and PaCO(2)>40 mmHg (sens. 92%, spec. 72%,). Sleep disordered breathing can reliably be predicted from simple daytime respiratory function tests, which, if applied systematically, will improve recognition of nocturnal respiratory failure.

Evaluation of postural tremor of finger for neuromuscular diseases and its application to the classification

The purpose of this study is to verify the features of the power spectrum of postural tremors for neuromuscular disease patients and to classify the postural tremors. The subjects were 88 neuromuscular disease patients (30 Parkinson disease (PD), 25 cerebellar disease (CER), 7 multiple sclerosis (MS), 7 neuropathy (NEU), 10 motor neuron disease (MND), 9 myopathy (MYO)). The control subjects were 12 normal young persons and 10 normal aged persons. Postural tremor was detected by accelerator sensor. Postural tremor was recorded under the two postural conditions: The subjects maintained the index finger without or with a weight load of 50 g in a horizontal position while looking at a visual target in front of the tip of the index finger. The power spectrum was calculated by an auto-regressive model (AR model). The peak frequency and the peak power were evaluated under the two conditions. Two frequency components of 8-12 Hz and 20-25 Hz appeared in the postural tremor of both normal subjects and neuromuscular disease patients. The difference of the postural tremor between the subjects mainly appeared in the 8-12 Hz component during the postural tremor with a weight load. MYO patients belonged to one group (called as group P1) due to lower peak power, CER patients belonged to one group (called as group P2) due to higher peak power, and PD and MS patients belonged to one group (called as group P3) due to lower peak frequency and higher peak power. NER and MND patients belonged to one group (called as group N which meant normal group). These results suggested that the peak frequency and the peak power of the 8-12 Hz component were changed by the conditions of both spinal reflex system and central nervous system. An oscillator within the central nervous system produced the underlying frequency of 8-12 Hz component, while the amplitude of 8-12 Hz component was governed by both spinal reflex system and central nervous system. In conclusion, the classification of postural tremor for neuromuscular disease patients was a useful index to elucidate the mechanism of tremor oscillation and to assist in clinical diagnosis of neuromuscular disease.

Hereditary neuromuscular diseases

This article presents the actual classification of neuromuscular diseases based on present expansion of our knowledge and understanding due to genetic developments. It summarizes the genetic and clinical presentations of each disorder together with CT findings, which we studied in a large group of patients with neuromuscular diseases. The muscular dystrophies as the largest and most common group of hereditary muscle diseases will be highlighted by giving detailed information about the role of CT and MRI in the differential diagnosis. The radiological features of neuromuscular diseases are atrophy, hypertrophy, pseudohypertrophy and fatty infiltration of muscles on a selective basis. Although the patterns and distribution of involvement are characteristic in some of the diseases, the definition of the type of disease based on CT scan only is not always possible.

Variation by diagnostic and practice pattern groups in the mobility outcomes of inpatient rehabilitation programs for children and youth

BACKGROUND AND PURPOSE

The purpose of this study was to describe variation in functional mobility outcomes among children and youth with different diagnoses and belonging to groups with different practice patterns from an inpatient pediatric rehabilitation hospital setting.

SUBJECTS

A sample of 138 individuals between the ages of 1 and 22 years (mean=9.4, SD=5.3) was enrolled.

METHODS

Physical therapists administered the "Mobility" domain of the Pediatric Evaluation of Disability Inventory at the time of admission and at the time of discharge. Mobility level (combined admission and discharge scores) and amount of change between and within 4 diagnostic groups (traumatic brain injury, non-traumatic brain injury, orthopedic, and neurological) and 5 neuromuscular and musculoskeletal practice pattern groups were calculated, and post hoc analyses were done for specific contrast comparisons.

RESULTS

Mobility scores between admission and discharge for all subgroups were different. Practice pattern groups were useful for identifying variations in level of motor performance. Diagnostic groups best described differences in mobility change during inpatient rehabilitation.

DISCUSSION AND CONCLUSION

The use of practice patterns as grouping categories may enhance our understanding of variation in clinical outcomes of children during inpatient rehabilitation.

Concentric-needle versus macro EMG. II. Detection of neuromuscular disorders

OBJECTIVE

Little is known about the relation and sensitivity of macro-EMG (MA-EMG) compared with concentric-needle EMG (CN-EMG) in the detection of neuromuscular disorders.

METHODS

CN-EMGs and MA-EMGs were recorded from the right brachial biceps muscle of 40 healthy subjects, aged 17-83 years, 20 patients with neurogenic disorders, aged 25-75 years, and 20 patients with myopathy, aged 18-76 years. Motor unit action potentials (MUAPs) were examined.

RESULTS

In patients with neurogenic disorders CN-MUAP duration, CN-MUAP amplitude, percent polyphasia, MA-MUAP amplitude, MA-MUAP area and fibre density were significantly increased. In patients with myopathy, only fibre density was significantly increased. In patients with neurogenic disorders, the sensitivity of CN-EMG was 80%, and that of MA-EMG 85%. In myopathies, the sensitivity was 50% for each technique. Pooling the results of both EMG techniques, the sensitivity increased to 90% in patients with neurogenic disorders, and to 65% in myogenic disease.

CONCLUSIONS

MA-EMG has a similar sensitivity in the detection of neuromuscular disorders as CN-EMG. Particularly when myopathy is suspected, both techniques should be applied if one is unrevealing.

MRI of Neuromuscular Disease: The Basics

Neuromuscular diseases are numerous and challenging to a variety of clinicians because patients may present to a variety of caregivers with nonspecific complaints. Difficulties in diagnosis and treatment toughen the management of this group. Advancements in the ability to see muscle lesions with magnetic resonance imaging (MRI) introduce radiologists to this complex field and at the same time confront clinicians with new issues, such as if and when to tap this technology on behalf of their patients. Like other published reviews on this topic, this article summarizes the current literature regarding MRI applications and limitations in neuromuscular diseases. It also asks, Given the obvious increment that MRI affords the evaluation of neuromuscular conditions, why is the test not applied more often?

Perioperative considerations for patients with musculoskeletal and neuromuscular disorders

This article first presents a brief description of musculoskeletal disease, then the anesthetic drugs that can trigger distress, and finally recommendations for perioperative nursing care based on pathophysiology and preservation of strength and function. The administration of a variety of anesthetic agents can exacerbate symptoms or result in unpredictable untoward effects on patients with musculoskeletal disease. Neuromuscular diseases result in diminished muscle strength. These deviations in structure and function must be considered when drafting a successful plan of care.

The contribution of molecular genetics in the diagnosis and management of neuromuscular disorders

It is true that the recent advances in molecular genetics have generated a medical revolution. This is especially true for the inherited neuromuscular disorders. There have been many spectacular recent discoveries with new genes being found and their protein products identified. One of the most remarkable aspects of this progress is the nexus which has developed between the basic discovery and its clinical application. As soon as a new genetic mutation is reported, the information may be used immediately to establish the molecular diagnosis for that disorder in any part of the world which has a DNA laboratory. This is done by using primers derived from the published DNA sequences using the polymerase chain reaction (PCR). This development is of immense value for the clinician as it provides an exact molecular diagnosis often with prognostic information and the test results can be used for genetic counselling and prenatal diagnosis. One of the unexpected outcomes of this work has been the surprising variation which has been shown to exist between genotype and phenotype. Previously, one mutation was believed to be responsible for one clinical disorder. However, it is now known that one genotype may be responsible for a variety of phenotypes and vice versa. In the field of neuromuscular disorders the most notable advances have occurred for Duchenne muscular dystrophy and the related dystrophinopathies and for the group of limb girdle muscular dystrophies, especially the subgroup of sarcoglycanopathies. Other areas are the congenital myopathies, the 'channel-opathies' and the mitochondrial cytopathies. In this review the most commonly used molecular genetic and immunocytochemical methods using antibodies to the protein product are outlined together with the principles of their application in the neuromuscular clinic. Included are the provisos and pitfalls which need to be kept in mind in the interpretation of DNA results for each patient.

Management of pulmonary complications in neuromuscular disease

The clinician working with patients with neuromuscular disease should be aware of the effects of muscle weakness on the respiratory system. Symptoms may present insidiously and can result in progressive loss of function, respiratory failure, and even death. A number of techniques, including several forms of mechanical ventilation as well as physical aids to assist airway hygiene, are available and are effective in improving symptoms and survival in appropriately selected patients with neuromuscular disease.

The role of physiatry in the management of neuromuscular disease

Patients with neuromuscular disease (NMD) are complex and pose a myriad of clinical problems. Management is best carried out by a team consisting of physicians, physical, occupational, and speech therapists, social workers, vocational counselors, and psychologists, among others. Physiatrists are well-suited to this type of multi-disciplinary care and can play a significant role in the care of these patients.

Management of cardiac complications in neuromuscular disease

Cardiovascular complications are common and varied in neuromuscular diseases. Knowledge of the complications specific to each disease is essential for appropriate screening for cardiovascular disease. Appropriate treatment of complications varies between neuromuscular diseases and draws primarily on experience from patients without neuromuscular disease. This article details the known cardiovascular complications and treatments for some of the major neuromuscular diseases.

Electrodiagnosis in neuromuscular disease

This article provides a general approach to the electrodiagnostic evaluation of the patient with neuromuscular disease. The electrodiagnostic findings in patients with various forms of peripheral neuropathy, motor neuron disease, neuromuscular junction disorders, and myopathy are presented. The pediatric electrodiagnostic evaluation is also discussed.

Vocational perspectives and neuromuscular disorders

The present study analyses the actual occupational situation, vocational handicaps and past labour career of a group of about 1000 Dutch patients suffering from a neuromuscular disorder (NMD). On the basis of the likelihood of a substantial employment history and sufficient numbers of patients, four types of NMD were selected: dystrophia myotonica (DM), hereditary motor and sensory neuropathy, (HMSN), spinal muscular atrophy (SMA) and myasthenia gravis (MG). Results show that a labour career is in reach of most NMD patients, even for those with severe limitations. It is concluded that physical limitations seem not to be decisive in that respect. The loss of the quality of communication, the loss of mental abilities and the effect of the diseases on the facial expression, as with some DM patients, are also important for chances on the labour market. Though the labour participation of NMD patients tends to decrease after the age of 34, the availability of work adaptations makes it possible to prolong the labour career. Analysis of the actual work situation of NMD patients shows that both disorder-related limitations and work characteristics play an important role in the amount of physical work problems encountered. It is argued that physical labour has to be regarded as generally unsuitable for NMD patients. This has implications for the sort and level of education to be attained by NMD patients. Career counselling as a focus point for the choice of an educational programme may improve labour market opportunities as well as quality of employment of NMD patients. Allowing for and accepting the possible effects of the disorder in the work situation are considered to be important in respect to labour participation and work satisfaction of workers with NMD. Reducing time pressure demands and increasing the freedom to organize one's work, are measures to be given especial consideration.

The Facial Disability Index: reliability and validity of a disability assessment instrument for disorders of the facial neuromuscular system

BACKGROUND AND PURPOSE

Disorders of the facial neuromuscular system can result in marked disfigurement of the face and difficulties in activities of daily living such as eating, drinking, and communicating. No systematic means of measuring the disability associated with facial nerve disorders exists. The purpose of this investigation was to examine the reliability and construct validity of the Facial Disability Index (FDI), a disease-specific, self-report instrument for the assessment of disabilities of patients with facial nerve disorders.

SUBJECTS AND METHODS

The FDI was administered to 46 ambulatory patients of the University of Pittsburgh Medical Center's Facial Nerve Center. The relationship of the FDI subscale and total scores with clinical impairment measures was determined, and a comparison of the use of the FDI and subscales of the more general SF-36 was made.

RESULTS

The FDI subscales produced reliable scores (theta reliability: physical function = .88; social/well-being function = .83). Construct validity of the FDI physical function subscale was demonstrated by a correlation with the clinician's physical examination of facial movement. The FDI social/well-being subscale was associated with the FDI physical function subscale and with a clinical assessment of psychosocial status within a subset of the sample (n = 14). The FDI represented the relationship between impairments, disability, and psychosocial status better than the generic SF-36 did.

CONCLUSION AND DISCUSSION

The FDI subscales produce reliable measurements, with construct validity for measuring patient-focused focused disability of individuals with disorders of the facial motor system.

Childhood neuromuscular disorders: a decade's experience in Saudi Arabia

The study describes the pattern of childhood neuromuscular disorders seen in a decade (1982-1992) at King Khalid University Hospital, Riyadh, Saudi Arabia. Similar data are scanty outside Europe and North America, and lacking in Saudi Arabia. Eighty-four children (< or = 16 years) were assigned to an entity of neuromuscular disease following review of the clinical, biochemical and neurophysiological data, and after re-examination of the histological and histochemical features of the muscle biopsies. Of the 84 ascertained cases, 40 (48%) had different forms of muscular dystrophy (MD), 26 (31%) had one of the various types of spinal muscular atrophy (SMA) and two (2.4%) hereditary motor and sensory neuropathy type I. The rest were miscellaneous cases including one (1.2%) with dermatomyositis. Of the dystrophies, severe childhood autosomal recessive muscular dystrophy (SCARMD) was more prevalent (30%) than Duchenne type (25%), conforming with observations from North African countries known to have a high incidence of consanguineous marriages. Family history of other cases of SCARMD included three males and three females, one of whom died at 15 years, and consanguinity was evident in 63%. Congenital MD, inherited in an autosomal recessive pattern, was also common (30%). A history of consanguinity was present in 55%. Of the 26 cases of SMA, type I (Werdnig-Hoffman disease) was the most prevalent (69%). Consanguinity was ascertained in 65% of SMA families and histories revealed another 14 affected siblings. Autosomal recessive forms seem to constitute the bulk of neuromuscular disorders in Saudi Arabia.

The genetic basis of neuromuscular disorders

In the last decade, our knowledge of human diseases genes has been growing rapidly as a result of the availability of resources and techniques for mapping and sequencing the human genome. New disease genes are now reported almost weekly. This review illustrates how the identification of genes involved in neuromuscular disorders has led to the characterization of not only novel genes, but also of a variety of different types of genetic mutation. These observations, which include high deletion frequencies, unstable tandem repeat sequences, genomic duplications and triplet repeat expansions, have facilitated the identification of similar types of mutation in other genetic disorders.

Congenital myopathies

The congenital myopathies (CM) are a group of non or little progressive neuromuscular conditions, often hereditary, delineated by morphological techniques, ie, enzyme histochemistry and electron microscopy. The catalogue of CM entailing well known "classic" conditions as central core disease, nemaline myopathy, and centronuclear myopathy has continuously been expanded, now comprising some 40 conditions. Nosologic advances have occurred with immunohistochemical techniques that show generalized or focal protein abnormalities within muscle fibers of certain CM, but at much slower pace as to localization of CM genes. So far, only those for central core disease, nemaline myopathy, and myotubular myopathy have been reported. Epidemiological rarity and nosographic controversy of CM have contributed to this lack of molecular genetic progress in CM.

Diagnosis in neuromuscular diseases

The diagnosis of neuromuscular diseases can be challenging and successful in the majority of patients, due to advancements in electrophysiology, muscle and nerve biopsy immunohistochemistry, and cytogenetics. This article reviews diverse topics, highlighting these recent achievements, with an emphasis on how they affect the clinical and laboratory diagnosis of specific neuromuscular disorders.