J.Z. Heckmatt

Ultrasound imaging in the diagnosis of muscle disease

A comparative study has been done of the static B-scan ultrasound appearance of the quadriceps muscle of the thigh in 60 new patients attending our muscle clinic and in 60 control children. In the control subjects there was good visualization of bone and fascia, which stood out clearly against the background of echo-free muscle tissue. Striking change was found in children with neuromuscular disease. Muscular dystrophies were associated with an increase in the intensity of echo reflected from the muscle substance, with corresponding loss of bone echo. Spinal muscular atrophies and neuropathies also showed an increase in muscle echo along with atrophy of the muscle and increase in depth of subcutaneous tissue. Various congenital myopathies also showed changes. Infants with hypotonia from nonneuromuscular causes had normal scans. Severity of change on the scan did not relate to functional disability, and some children had good function yet strikingly abnormal scans. Three degree of change on the scan correlated with the degree of disruption of muscle architecture on biopsy. Ultrasound imaging has proved to be a useful, noninvasive screening tool in the investigation of children with neuromuscular disease.

Sleep studies and supportive ventilatory treatment in patients with congenital muscle disorders.

Eight ambulant children aged 6-13 years, four with congenital myopathy, two with congenital muscular dystrophy and two with the rigid spine syndrome, presented with recurrent chest infections, morning headaches, shallow breathing at night, or respiratory failure. Polysomnography confirmed the presence of nocturnal hypoxaemia with oxygen saturation on average less than 90% for 49% of sleep and less than 80% for 19% of sleep accompanied with severe hypoventilation. Additionally there was sleep disturbance characterised by an increased number of wake epochs from deep sleep (in comparison to 10 non-hypoxaemic subjects). The severity of sleep hypoxaemia did not correlate with symptoms. Treatment with night time nasal ventilation was started and repeat polysomnography showed normal overnight oxygen saturation and a reduced number of wake epochs during deep sleep. It is important to be vigilant for sleep hypoventilation in these patients and sleep studies should be part of the routine respiratory evaluation. Treatment with nasal ventilation is effective in reversing the nocturnal respiratory failure without significant disturbance to life style.

PROLONGATIÓN OF WALKING IN DUCHENNE MUSCULAR DYSTROPHY WITH LIGHTWEIGHT ORTHOSES; REVIEW OF 57 CASES

Fifty‐seven boys with Duchenne muscular dystrophy aged between 6 years 3 months and 13 years 6 months, who were at the point of losing the ability to walk or had recently done so, were fitted with lightweight knee‐ankle‐foot orthoses to re‐establish walking. 47 walked well and independently in their orthoses, achieving good stability and confidence. 20 are still ambulant; the other 27 stopped walking at intervals ranging from eight to 48 months. Prolongatión of walking prevented the development of scoliosis, joint contractures and deformities and also benefited the boys psychologically.

Prevention of rapidly progressive scoliosis in Duchenne muscular dystrophy by prolongation of walking with orthoses.

We reviewed the incidence and severity of scoliosis in 93 boys with Duchenne muscular dystrophy who had been rehabilitated in light-weight knee-ankle-foot orthoses at the point of loss of ambulation, between the ages of 6 and 12 years. There was an inverse relationship between the severity of the scoliosis and the age walking was lost in the orthoses. The scoliosis was less severe in the 20 boys (22%) who walked in their orthoses beyond 13 years of age than in those who stopped walking in their orthoses before 13 years. There was also a rapid deterioration in the scoliosis between the ages of 13 and 15 years in boys who had stopped walking in their orthoses before the age of 13 years, while in comparison, boys of the same age who were ambulant in their orthoses beyond 13 years showed a much slower rate of deterioration. These results strongly suggest that walking in orthoses beyond the age of 13 years prevented rapid progression of scoliosis between 13 and 15 years of age, ie, during the pubertal growth spurt. (J Child Neurol 1988;3:269-274).

Scoliosis in Spinal Muscular Atrophy: Review of 63 Cases

We reviewed the incidence and severity of scoliosis in 37 patients with the intermediate type and 26 with the mild type of spinal muscular atrophy. In the intermediate type, scoliosis has an early onset and rapid progression before puberty, and a spinal fusion will be needed in virtually all cases. This rapid progression occurred despite routine use of a spinal brace. Hip dislocation was frequently present but, in most cases, was secondary to the pelvic tilt and did not contribute to the scoliosis. In the mild type, the scoliosis was more variable. In the 30% of patients who had scoliosis, progression was rapid during puberty but only in those who had lost ambulation. Of the four children with the intermediate type and the seven with the mild type who walked in light-weight orthoses, progression of scoliosis was slow, except in those who had lost ambulation. The ultimate effect of walking in orthoses is difficult to assess because of small numbers, but it seems to slow or at least delay progressive scoliosis. (J Child Neurol 1989;4:118-123).

A randomized controlled trial of early surgery in duchenne muscular dystrophy

We performed a randomized controlled trial of early surgical treatment of contractures in 20 boys with Duchenne muscular dystrophy, age 4-6 yr. Surgery consisted of release of hip flexors, removal of iliotibial bands, and lengthening of tendo Achilles bilaterally. All patients were monitored for at least 12 months post-randomization, and assessed quantitatively for muscle strength and function. Surgery corrected the deformities, but had no beneficial effect on strength or function. Indeed, data in the second year showed more rapid deterioration of function in some of the operated boys. There appeared to be continued evolution of pathology following surgery, as assessed by sequential muscle ultrasound and muscle biopsy. We cannot recommend this type of surgery as a routine treatment.

CORRELATION OF CLINICAL AND DELETION DATA IN DUCHENNE AND BECKER MUSCULAR DYSTROPHY, WITH SPECIAL REFERENCE TO MENTAL ABILITY

We report the results of screening for molecular deletions in 164 boys with DMD and BMD and correlation of deletions with clinical features. A deletion was detected in 100 cases (61%) by Southern blot hybridization analysis with cDNA probes. Thirty-eight different deletions and two duplications were identified. All deletions except one (deletion of exons 48-53) found in males with DMD disrupted the translational reading frame of the gene; however, six deletions in boys with BMD were out of frame. The same deletion in different individuals was found to occur with or without mental impairment, and many different deletions were associated with mental retardation. We were able to ascertain a series of boys [from this study and a previous one (Hodgson S V, Hart K, Abbs S, et al. Correlation of clinical and deletion data in Duchenne and Becker muscular dystrophy. J Med Genet 1989; 26: 682-693)] without significant mental retardation who had deletions which, when combined, covered the whole region of the gene in which deletions are commonly found, and within which region individual deletions can be associated with mental retardation.

Ultrasound Imaging and Directed Needle Biopsy in the Diagnosis of Selective Involvement in Muscle Disease

Four children investigated for neuromuscular disorder by routine ultrasound imaging showed selective involvement within the quadriceps femoris muscle, with involvement of the vasti and sparing of the rectus femoris. This was confirmed by concurrent needle biopsy of the two muscles. Real-time ultrasound imaging is quick, noninvasive, readily accepted by children, and has the advantage over CT scans of being practical for routine outpatient use. Needle biopsy is relatively atraumatic and enables one to select specific superficial and deep muscles for concurrent biopsy. ( J Child Neurol 1987; 2:205-213).

Cerebral ventricular dilation in congenital myotonic dystrophy

Ultrasonography or computed tomography scanning of the brain was performed in 10 infants with congenital myotonic dystrophy between the age of 1 day and 2 months, and showed intracranial abnormalities in all. Ventricular dilation was diagnosed in eight (80%), subarachnoid hemorrhage in one, and white matter infarcts in one. The common finding of ventricular dilation is probably related to developmental brain abnormality dating back to fetal life, because it was already present in three infants scanned on the first day of life. Neonatal asphyxia was present in seven infants, associated with intraventricular hemorrhage in two. The relationship between these changes and mental retardation, which is a common feature in this disease, is unclear.

Use of nerve conduction velocity to determine gestational age in infants at risk and in very-low-birth-weight infants

Nerve conduction velocity was used to measure gestational age in at risk and very-low-birth-weight neonates. The method gave highly significant correlations with gestational estimates by the Dubowitz score and with confirmed maternal dates; 86% of the estimates agreed within two weeks with confirmed maternal dates. The method is valid in babies 30 weeks old or younger and is reproducible after the first postnatal week. There was no difference in babies small for gestational age. The technique was estimated to predict gestation with a standard deviation of +/- 1.14 weeks.