Muscle weakness and wasting may be evaluated objectively by dynamometry and compound ultrasound imaging. We have measured the voluntary isometric strength of the quadriceps muscles of healthy women in their 70s (n = 25) and in their 20s (n = 25) and have compared it with the mid-thigh cross-sectional area of the same muscles. The two groups of women showed similar variability when strength was measured on consecutive days (coefficients of variation: 8%). The older women were 35% weaker than the young women (P less than 0.001) and their quadriceps cross-sectional area was 33% less (P less than 0.001). Quadriceps strength and cross-sectional area were correlated (r = 0.66, P less than 0.001, elderly; r = 0.53, P less than 0.01, young) and the principal axis of the relationship was closely similar for the two groups of women. There is therefore no difference in the intrinsic strength of the quadriceps muscles of healthy women in their third and eighth decades. This report also provides normative data for the objective evaluation of quadriceps weakness and/or wasting in female patients. The techniques involved are straightforward, the dynamometer is easily made, and compound ultrasound imaging is widely available.

Size and strength of the quadriceps muscles of old and young women

Chronic neuromuscular diseases may affect all major respiratory muscles groups including inspiratory, expiratory, and bulbar, and respiratory complications are the major cause of morbidity and mortality. Untreated, many of these diseases lead inexorably to hypercapnic respiratory failure, precipitated in some cases by chronic aspiration and secretion retention or pneumonia, related to impairment of cough and swallowing mechanisms. Many measures are helpful including inhibition of salivation, cough-assist techniques, devices to enhance communication, and physical therapy. In addition, ventilatory assistance is an important part of disease management for patients with advanced neuromuscular disease. Because of its comfort, convenience, and portability advantages, noninvasive positive pressure ventilation (NPPV) has become the modality of first choice for most patients. Patients to receive NPPV should be selected using consensus guidelines, and initiation should be gradual to maximize the chances for success. Attention should be paid to individual preferences for interfaces and early identification of cough impairment that necessitates the use of cough-assist devices. For patients considered unsuitable for noninvasive ventilation, invasive mechanical ventilation should be considered, but only after a frank but compassionate discussion between the patient, family, physician, and other caregivers.

Pulmonary complications of chronic neuromuscular diseases and their management.

THE muscular dystrophies comprise several groups of inherited disorders with a wide variation between the groups in the distribution and severity of muscle involvement.1 The respiratory muscles, in...

Practical problems in the respiratory care of patients with muscular dystrophy.

In six patients with Cushing's syndrome and three with steroid myopathy, the clinical, functional, biochemical and structural characteristics of myopathy are described. Proximal muscle weakness occurred in all the patients, preferentially affected the lower limbs and was accompanied by muscle wasting in all but one patient. Force measurements confirmed quadriceps weakness in every patient. Vastus lateralis muscle biopsies showed light microscopic abnormalities in two of three patients with steroid myopathy and one of five patients with Cushing's syndrome. Type II fibre atrophy was the commonest abnormality. Reduced type II mean fibre areas occurred in all the patients with steroid myopathy and were common in Cushing's syndrome patients. Type I mean fibre areas were also reduced in two of the former group and one of the latter group and two further patients in this group had areas at the lower end of the normal range. Abnormalities in electron microscopy, mitochondrial function tests and chemical content of skeletal muscle were frequent and are described and discussed. A plasma creatine kinase activity (CK) at the lower end of the normal range, a myopathic electromyogram (EMG) and a raised 24-h urinary 3-methylhistidine/creatinine ratio on a creatine free diet were other characteristic findings in both groups of patients.

Corticosteroid myopathy: a clinical and pathological study

One hundred and seven patients with polymyositis or dermatomyositis were followed for an average of 5 years. In 100 patients it was possible to evaluate the effect of treatment with steroids or a combination of steroids and immunosuppressive drugs. Fifty patients improved, 50 did not. Compared with the treatment-resistant group the treatment-responsive patients were of younger age, did not have an associated malignancy or cardiac disease and began treatment within 24 months after the onset of muscular weakness. In the treatment-responsive group the degree of improvement was correlated to the mean dose of steroids given during the first 3 months of treatment. Eighty-seven per cent of surviving responsive patients had no or slight disability at the end of the investigation. The mortality rate was 23% and was highest in the treatment-resistant group. Comparison between different treatment programs was possible and based on the results, a treatment schedule could be recommended. The principles of this schedule are: During the first month high doses of prednisone or prednisolone should be given daily. From the second month, an alternate-day administration can be employed. Tapering to maintenance dose should be gradual and slow. The treatment period should be long. The mean duration in the present series was 27 months.

Polymyositis – treatment and prognosis

SUMMARY

Many children with muscular dystrophy are overweight, and although weight control is pursued in some centres it is unusual to encourage severe dietary restriction for fear that it might lead to accelerated loss of muscle. In this study, two overweight boys with muscular dystrophy were monitored by whole-body nitrogen balance, total body potassium, strength and functional measurements during calorie restriction. Both patients were found to have a transient loss of nitrogen on commencing the low caloric intake: thereafter, weight loss was not found to have any deleterious effect on muscle bulk or function in either patient. It is suggested that controlled weight-reduction in obese children with muscular dystrophy is a safe and practical way of losing excess fat, which can improve mobility and self-esteem, and may possibly effect longevity.



RESUME

Reduction de poids chez les garcons atteints de myopaihie



Beaucoup de jeunes myopathes sont obeses et le controle du poids est applique dans quelques centres. Cependant, il est inhabituel de favoriser des regimes stricts par crainte que cela accelere la perte de muscle. Dans cette etude, deux myopathes obeses ont ete suivis en fonction de l'equilibre azote du corps entier, le potassium total, la force et les appreciations fonctionnelles au cours d'une restriction calorique. Une perte transitoire azotee au debut du regime faible en calories a ete notee chez les deux sujets, cependant la perte de poids n'a semble avoir aucun effet nefaste sur la forme ou la fonction du muscle chez l'un ou l'autre des enfants. I1 est suggere qu'une reduction de poids controlee chez les jeunes myopathes obeses est un moyen sur et pratique d'une perte de graisse excessive qui peut ameliorer la mobilite et l'appreciation de soi et qui peut eventuellement agir sur la longevite.



ZUSAMMENFASSUNG

Gewichtsreduktion bei Jungen mit Muskeldystrophie



Viele Kinder mit Muskeldystrophie haben Ubergewicht und in einigen Zentren werden daher Gewichtskontrollen durchgefuhrt. Eine strenge Diat wird jedoch in der Regel nicht empfohlen, da man furchtet, daβ dadurch der Muskelschwund beschleunigt werden konnte. In dieser Studie wurden zwei ubergewichtige Jungen mit Muskeldystrophie unter einer kalorienarmen Diat hinsichtlich ihrer Gesamtstickstoffbilanz und ihres Gesamtkaliums uberpruft und es wurden Kraft- und Funktionsmessungen durchgefuhrt. Beide Patienten hatten zu Beginn der Diat einen vorubergehenden Verlust an Stickstoff. Danach hatte der Gewichtsverlust keinen nachteiligen Effekt auf die Muskelgroβe oder—funktion. Es wird empfohlen, daβ bei adiposen Kindern mit Muskeldystrophie die kontrollierte Gewichtsreduktion ein sicherer und praktikabler Weg ist, uberschussiges Fett abzubauen, wodurch die Beweglichkeit und das Selbstwertgefuhl gebessert und eventuell die Uberlebensdauer erhoht werden konnten.



RESUMEN

Reduccion de peso en ninos con distrofia muscular



Muchos ninos con distrofia muscular tienen sobrepeso y en determinados centros se persigue un control del peso. Sin embargo, no es corriente animar a seguir una dieta restrictiva por miedo a que ello pudiera acelerar la perdida de musculo. En este estudio, dos muchachos con sobrepeso con distrofia muscular fueron monitorizados para el balance de nitrogeno total, potasio corporal total mediciones de fuerza y funcion durante la restriccion calorica. Se ha11o que ambos pacientes tenian una perdida transitoria de nitrogeno al iniciar la restriccion calbrica. A partir de aqui no se vio que le perdida de peso tuviera ningun efecto deletereo sobre la masa muscular o sobre su funcion en ningun paciente. Se sugiere que la reduccion controlada de peso en ninos obesos con distrofia muscular es una manera prlctica e inocua de perder exceso de grasa, lo cual puede mejorar la movilidad y autoestima y puede probablemente afectar a la longevidad.

Weight reduction in boys with muscular dystrophy

Muscle breakdown and repair were measured by metabolic balance techniques in a patient with polymyositis who was being treated with prednisolone and azathioprine Changes in body muscle mass that had been estimated from nitrogen and phosphorus balances correlated with antropometric assessments of thigh muscle mass and quadriceps strength Decline in muscle strength was associated with a net rate of muscle breakdown of 148 g/day Recovery was associated with a net rate of muscle repair of up to 100 g/day Early reduction in corticosteroid treatment appeared to enhance the rate of repair Changes in the isometric contraction force of the quadriceps muscle (but not in clinical symptoms, plasma creatine kinase [CK] or erythrocyte sedimentation rate [ESR] were found to reliably indicate whether the muscle was in a state of breakdown or repair Treatment of the individual patient may be quantitatively monitored by metabolic balance studies or, more simply, by measurement of muscle strength

J. M. Round

Papers

Weight reduction in boys with muscular dystrophy

Muscle breakdown and repair in polymyositis: a case study.