[Clinical significance of dystrophin test for patients with various neuromuscular diseases--immunofluorescence and immunoblot analyses of dystrophin abnormalities]

The dystrophin test was performed on skeletal muscle specimens from 81 cases with various neuromuscular diseases by using two new monoclonal antibodies. The results were compared with those obtained by using four polyclonal antibodies. These monoclonal and polyclonal antibodies were raised against various portions of the dystrophin molecule. On immunohistochemical analysis, the two new monoclonal antibodies showed the same staining pattern as the four polyclonal antibodies. Non-specific immunostaining of the cytoplasm, often seen with polyclonal antibodies, was not observed with monoclonal antibodies. With the application of monoclonal antibodies, the connective tissue sometimes showed non-specific immunostaining which originated from the second fluorescent antibody. On immunoblot analysis, one of the two monoclonal antibodies, antibody 4-4 C 5, showed weak immunoreactivity, and the 400 kDa dystrophin band was not detected. Three cases out of 15 with Duchenne muscular dystrophy (DMD), and one case out of 3 with limb-girdle type muscular dystrophy which had previously been diagnosed on the basis of clinical data, were found to have non-dystrophin-related muscular dystrophy, and Becker muscular dystrophy (BMD), respectively. Three and two of five cases were diagnosed as DMD and BMD, respectively, though clinical diagnosis had not been possible because they were too young. Clinical diagnosis of congenital muscular dystrophy was confirmed in 9 patients by the dystrophin test. Only one of three certain DMD carriers had a so-called mosaic staining pattern. We conclude that all six antibodies are useful tools for the diagnosis of neuromuscular diseases, because of their high specificity for dystrophin.

Item assessment in the development of a diagnostic motor performance test for myopathy in children

The authors conducted an assessment study of newly developed motor performance items for the diagnosis of myopathy. 17 children who had had muscle biopsy for this diagnosis in the recent past were administered 14 items based on the measurement of static, dynamic and explosive muscle strength and muscle endurance. Individual items did not have perfect discriminative power, but the results were encouraging enough to warrant detailed study with combinations of the items, so that in future fewer children will have to undergo unnecessary muscle biopsies.

Preliminary observations on the neuromuscular abnormalities in patients with organ failure and sepsis

OBJECTIVE

To estimate the incidence and nature of neuromuscular abnormalities in a representative group of ITU patients.

DESIGN

Prospective sequential study.

SETTING

Teaching hospital ITU.

PATIENTS

23 patients who eventually stayed > 7 days on ITU who had no contraindication to muscle biopsy and whose relatives gave informed consent.

MEASUREMENTS AND RESULTS

Muscle histopathology, neurophysiological studies, record of all drugs administered, APACHE II score, organ system failure score, presence or absence of sepsis, clinical evaluation of neuromuscular problems, time to hospital discharge. Heterogeneous neuromuscular abnormalities were present in 22 out of 23 patients studied and included axonal neuropathy, denervation, generalised fibre atrophy, non-specific myopathy and necrotising myopathy.

CONCLUSION

Neuromuscular abnormalities are almost invariable in longstay intensive care patients and the resulting weakness may seriously delay hospital discharge. Various abnormalities were seen but no obvious aetiological factors were identified. The origin of the abnormalities is probably multifactorial.

Content validity of the In-Hand Manipulation Test

Object manipulation skills are a vital area for client assessment in occupational therapy, but in-hand manipulation skills are not specifically included in any standardized tests of hand function for children. The In-Hand Manipulation Test (IMT) was developed for use by occupational therapists with preschool and young school-age children. Assessment of the IMT's content validity was an important precursor to further development of the test. Twenty-four certified occupational therapists rated young children's performance during administration of the IMT before completing a content validity survey about the test. Overall, the IMT's content validity was supported by the feedback from the raters. A final test length of 50 items with two trials per item was considered acceptable, provided that the test takes no longer than 20 to 30 min to administer. The therapists were positive about the content and structure of the rating scale and the approach used in presenting activities to the children. Some issues related to functional validity of some skills or the proportions of in-hand manipulation skills were raised. Further development of the IMT for clinical and research use seems warranted. Revisions to the test will be made, and another pilot study will be conducted before normative data collection. Training for administering and scoring the test will incorporate the recommendations on the basis of this study's results.

Neuromuscular diseases in children

Our understanding of neuromuscular disorders has advanced considerably in recent years with developments in molecular genetic techniques. In some conditions we now know the basic pathological defect and, in many, prenatal diagnosis is now available. This review considers the common clinical problems that confront clinicians.

Development of muscle power in preterm infants: individual trajectories after term age

In a longitudinal study individual trajectories were traced for the developing relationship between active and passive muscle power in preterm (n = 37) and fullterm (n = 20) infants from term to 24 weeks (corrected) age. Such trajectories should enable the identification of those infants at highest risk for later neurological dysfunctions. This contention is supported by the findings of this study: those preterm infants who showed marked discrepancies between the two sorts of muscle power or rigidity in both beyond 12 weeks corrected age were most likely to manifest neurological problems at 52 weeks of age.

The electrodiagnostic examination with myopathies

The values and limitations of the electrodiagnostic examination in assessing patients with possible myopathies are discussed. Limitations include: (1) no findings are specific for muscle disease; (2) the particular changes may be quite diverse; (3) myopathies of different etiologies may have the same presentation, whereas the same myopathy may have different presentations at different times; (4) a specific myopathy cannot be diagnosed; and (5) the ability to diagnose myopathy may be seriously compromised by the presence of certain disorders. Benefits include: (1) widespread muscle sampling; (2) help in determining most appropriate muscle for biopsy; (3) ascertaining, to some extent, the type of myopathy present, depending on the particular findings; (4) distinguishing entities often confused clinically with myopathies; (5) recognizing abnormalities (e.g., myotonic discharges) otherwise undetectable. Both the clinical and electrodiagnostic presentations of myopathies are discussed. Regarding the latter, the potential or actual changes seen with each component of the electrodiagnostic assessment (nerve conduction studies, late responses, repetitive stimulation studies, needle electrode examination, quantitative electromyographic studies) is reviewed.

Comparison of in vitro contracture testing with ryanodine, halothane and caffeine in malignant hyperthermia and other neuromuscular disorders

In vitro exposure of living skeletal muscle to ryanodine has been proposed as a potentially specific test for malignant hyperthermia (MH). In this study we have compared in vitro contracture responses to halothane, caffeine and ryanodine in skeletal muscle specimens obtained from 155 patients attending for diagnosis of susceptibility of MH and also from six patients having muscle biopsy for diagnosis of other neuromuscular disorders. Although the ryanodine contracture test was not specific for MH, the results suggest it may greatly aid (in conjunction with the standard halothane and caffeine contracture tests) the accurate phenotyping of individuals that is essential for the further genetic analysis of MH.

Clinical neurophysiology of generalized polyneuropathy

Clinical electrophysiologic measures derive from sound neurophysiologic principles and provide sensitive, objective information useful in the evaluation of generalized polyneuropathy. The electrodiagnostic examination includes sensory and motor nerve conduction studies, evaluation of late responses, and needle electromyography. These measures represent an extension of the neurologic examination. Clinicians use electrodiagnostic information to confirm clinical findings, localize specific abnormalities to a degree not clinically possible, and identify the underlying pathophysiology. Although the primary role of clinical electromyography is diagnostic, test results are sufficiently sensitive to identify subclinical findings and to monitor small changes related to disease progression or treatment response. In some peripheral disorders, electrodiagnostic information provides the most sensitive indicator of prognosis. Classification of generalized polyneuropathy using electrophysiologic information focuses the differential diagnosis, directs the subsequent evaluation, and often suggests a specific diagnosis or class of disorders. Several of the most common treatable polyneuropathies were rarely diagnosed 25 years ago. Awareness of these disorders relates to increased utilization of clinical electrophysiology and identification of characteristic electrodiagnostic features that result in their recognition.

Clinical neurophysiology of disorders of the neuromuscular junction

This is a review of the neurophysiological techniques used clinically to demonstrate abnormalities of neuromuscular transmission. The use of these tests in myasthenia gravis, Lambert-Eaton myasthenic syndrome, congenital myasthenic syndromes, and other conditions with disturbed neuromuscular transmission is presented.

[Respiratory monitoring during sleep]

A review of respiratory disorders of sleep with the possible related clinical alterations are described. Techniques and methods used in non-invasive respiratory monitoring during sleep are presented. Diagnostic events and therapeutic approaches are discussed related to special patient groups: the obstructive sleep apnoea syndrome, asthma, chronic obstructive pulmonary disease and neuromuscular diseases.

Neurologic findings in neonates with intrauterine cocaine exposure

To determine the effects of prenatal cocaine exposure on intrauterine growth and neurologic function, 30 term infants were evaluated prospectively: 14 cocaine-exposed and 16 unexposed. Cocaine-exposed infants had significantly lower mean birth weights, birth lengths, and head circumferences than urine-negative controls. Neurologic abnormalities among cocaine-exposed newborns included hypertonia of any type (86% vs 33%), axial hypertonia (79% vs 19%), plantar extension (46% vs 19%), and coarse tremor (57% vs 12%). The degree of hypertonia was sufficiently severe to warrant a diagnosis of "hypertonic tetraparesis" in 64% of cocaine-exposed and 12% of unexposed infants (P = .007). This diagnosis was highly correlated to small head size (r = 0.48; P = .01). Persistent tonic downward gaze was evident in two neurologically abnormal cocaine-exposed newborns. Gaze abnormalities improved slightly over the next 3 weeks of observation. One such infant re-evaluated at 6 months of age revealed resolution of tonic downward gaze and neurologic findings. We conclude that prenatal cocaine exposure is associated with tone and movement abnormalities in newborn infants.

Pathophysiological studies of neuromuscular function in subacute organophosphate poisoning induced by phosmet

A 51 year old man developed progressive cranial and proximal muscle weakness, hyperreflexia and mental change. The disorder progressed over 9 days following the fifth weekly spraying with the organophosphate (OP) insecticide, phosmet, with limited symptoms of acute toxicity. Marked decremental responses of 50-80% on slow and fast rates of stimulation were improved to 15% by edrophonium or neostigmine. Intracellular recordings at the endplate region of intercostal muscle revealed small miniature endplate potentials (mepps), reduced mean acetylcholine sensitivity and normal membrane potentials. Electronmicroscopy revealed degeneration and regeneration of the endplates. This study demonstrates that OP poisoning due to phosmet can produce a subacute postsynaptic neuromuscular syndrome without marked symptoms of acute toxicity.

Temporal and spatial parameters of gait in children. II: Pathological gait

Temporal and spatial parameters of gait were measured in 72 children with anomalous walking patterns as a result of neuromuscular impairment, 21 with childhood hemiplegia, 27 with congenital paraplegia and 24 with miscellaneous neuromotor disorders. Measurements were compared with those for a group of normal children. In all three groups, step length, average maximum foot-velocity and walking speed were reduced, double support time was increased, while cadence deviated from normal in both directions. Hemiplegic children varied considerably in their measured side-to-side gait asymmetries, suggesting a range of gait abnormalities not specified by subjective means alone. Measured gait parameters were significantly related to Hoffer grade of functional mobility in paraplegic children. Objective gait analysis using established temporal and spatial measurements is of clinical value in the management of childhood neuromuscular disorders.

[Motor neuropathy with conduction blocks]

A series of 4 patients with pure, chronic and progressive motor neuropathy whose main clinical characteristics were asymmetric and distal weakness of the upper limbs, myokymia and fasciculations is presented. There were no sensory impairment and amyotrophy was observed in only one case. This picture suggested the diagnosis of motor neuron disease (MND). However, neurophysiologic examination demonstrated the presence of multifocal conduction blocks (CB) of the motor axons which were preferentially located in the proximal nerve segments and always at points atypical to nerve compression. The peripheral sensitive conductions and the somatosensory evoked potentials were normal, even through the nerve segments where the CB were located. Since this is a treatable potentially reversible syndrome, this motor neuropathy with CB should be included in the differential diagnosis of MND.

Neuromuscular complications of sepsis

Sepsis and multiple organ failure are major problems in medical and surgical intensive care units. Critical illness polyneuropathy occurs in 70% of these patients. Difficulty in weaning from the ventilator is an early sign. Electrophysiological studies are necessary to establish the diagnosis; these studies show an axonal degeneration of peripheral nerve fibres. Recovery occurs in weeks or months, depending upon severity. Muscle biopsy reveals denervation atrophy. Sepsis itself does not induce a neuromuscular transmission defect, but neuromuscular blocking agents may increase the severity of critical illness polyneuropathy. If steroids are used in addition to neuromuscular blocking agents, a severe myopathy may result. Other effects on muscle are cachectic myopathy and panfascicular muscle fibre necrosis. A variety of combinations of these conditions may affect the same patient. Only well-designed prospective studies will determine the true effect of these medications on the neuromuscular system in septic patients.

[Mixed cryoglobulinemia and vasculitic neuromyopathy]

Over a period of 25 years, a 67-year-old man again and again developed purpura over the lower legs. When hospitalized because of splenomegaly with thrombocytopenia the diagnosis of idiopathic thrombocytopenic purpura was made. Four years later, after an infection of the upper respiratory tract, purpura again developed, together with a symmetrical sensory-motor polyneuropathy with flaccid paraparesis. Biopsy of the N. suralis revealed a florid leukocytoclastic vasculitis. Morphologically there was severe nerve damage with Wallerian degeneration and subtotal nerve fibre loss. Immunological tests demonstrated essential mixed cryoglobulinaemia of IgG/IgM type. Cryoprecipitates must be considered as the cause of the vasculitis, which in turn produced the nerve lesions and purpura. This case underlines the importance of biopsy diagnosis of peripheral nerve and skeletal muscle, because it may demonstrate a treatable cause of a severe acute neuromyopathy.

Turns-amplitude analysis of the electromyographic recruitment pattern disregarding force measurement. II. Findings in patients with neuromuscular disorders

Turns-amplitude analysis of the electromyographic recruitment pattern was performed on-line in the brachial biceps muscle of 46 patients with neuromuscular disorders using the mean amplitude as an indicator of force. The parameters, peak-ratio (PR) and number of time intervals (TI) from 0 to 1.5 ms, were increased in patients with myopathy. In patients with neurogenic involvement, the characteristic pattern was a decreased PR and a decreased incidence of TI between 0 and 1.5 ms. The results indicate that the two parameters supplement each other as some of the patients were identified only by one or the other. In patients with myopathy, the method had a higher diagnostic yield than the individual motor unit action potential analysis. The method is objective, fast, and reliable.

[Neurometabolic diseases. References for classification, clinical aspects and diagnostic procedures]

Diseases caused by neuro-metabolic or neuro-degenerative disorders often lead to diagnostic difficulties, because of their rarity and numerous quantity. The present report tries to combine older classifications according to anatomic aspects with the newer ones underlying biochemical-functional points of view. Then the most important cardinal symptoms in a synoptic demonstration are put in relation to the most considerable neuro-metabolic disorders. Tables concerning age-related diseases and informations on diagnostic methods of importance are presented.