Computed tomography in dystrophia myotonica

Variability in human quadriceps muscles: quantitative study and review of clinical literature

Knowledge of variations in normal human thigh musculature is important for the interpretation of various clinical and biomedical investigations. In this study, cross-sections from whole thighs of 34 cadavers were analyzed qualitatively and morphometrically. Sections were cut from right and left limbs at three levels in the region often used for muscle biopsy. Measurements were made of limb circumferences and cross-sectional areas of the three vasti and of the femur, and of the extent of overlap and fusion between the vasti on the lateral aspect of the thigh. Limb circumference proved to be a good predictor of total cross-sectional area of the quadriceps muscle. Large individual variations were found for most measurements but especially for the amount of fusion between the muscle bellies of vastus lateralis and vastus intermedius. Significant differences were found for most variables between the three levels, but there were few differences between sides except for the cross-sectional area of vastus lateralis which was greater on the right at the most distal level. These variations in size and form of thigh musculature should be considered when interpreting data obtained from muscle biopsy, imaging, biomechanical, electromyographic, and functional studies of the human thigh. Review of the literature on variability of quadriceps muscle and its clinical relevance showed a diversity of approaches but insufficient definitive data suitable for interpreting functional outcomes in response to exercise or following surgery. Further work is suggested combining current anatomical datasets with advanced imaging techniques capable of determining muscle fiber orientation and fiber type composition, and including 3D reconstruction.

CT muscle imaging and the clinical assessment of neuromuscular disease

Twenty patients with neurogenic disorders, polymyositis, or muscular dystrophies were assessed clinically and by CT imaging of limb, limb girdle, and trunk muscles, using a standard protocol. On each side of these patients 26 movements were graded by the MRC scale, and 20 muscles were assessed by CT imaging. The clinical and CT findings could be compared, in a blind evaluation, in 10 muscles on each side. A quantitative assessment of the CT muscle images were also made. The CT images showed striking abnormalities, even in many muscles of normal strength by clinical testing. Asymmetrical involvement of muscles was found in all the disorders studied, even when not suspected on clinical examination. Muscles in patients with muscular dystrophy were more abnormal than those in patients with neurogenic disorders. In polymyositis the attenuation values were intermediate to the other two groups. A "washed-out" appearance with very low attenuation values was very suggestive of muscular dystrophy. Involvement of paraspinal and rectus abdominis muscles was uncommon in neurogenic disorders. The gracilis muscle was relatively resistant to degeneration. CT imaging can enhance the clinical assessment of patients with neuromuscular disease, often revealing unexpected abnormalities.

Imaging techniques in myotonic dystrophy. A comparative study of ultrasound, computed tomography and magnetic resonance imaging of skeletal muscles

Limb and trunk muscles of 57 patients with the juvenile or adult form of myotonic dystrophy were studied by imaging techniques (ultrasound, computed tomography, magnetic resonance imaging). Typical findings were atrophy of the tibialis anterior and triceps brachii muscles and fatty degeneration of the vastus intermedius, sartorius, tibialis anterior and soleus muscles as well as of medial head of the gastrocnemius muscle. Magnetic resonance imaging was the most sensitive technique in depicting mesenchymal muscle alterations, followed by computed tomography and ultrasound. The data support that imaging is more sensitive in detecting the myopathy than measurement of the creatine kinase activity.

An unusual familial muscle disorder

Autosomal dominant inheritance of an unusual muscle disease is reported in a family. The pathological appearance, of regularly arranged markedly atrophic muscle fibres without other evidence of disturbed innervation, are similar in each case. However, the onset of the disease, its distribution and its progression has varied within the family.

CT muscle scanning in the evaluation of patients with spinal muscular atrophy (SMA)

One hundred patients with spinal muscular atrophy (SMA) were assessed by CT scanning using a standardised technique. The spectrum of CT abnormality occurring in SMA was observed and by overall analysis the patients were divided into 4 groups. While the CT appearances of these groups correlated well with clinical assessment of severity of disease, the disease process was usually much more widespread than clinical examination suggested. CT abnormality was first observed in the leg and gluteal muscles, progressing to the posterior spinal, thigh, shoulder girdle and sternomastoid muscles. Hypertrophy of sartorius and gracilis was observed in a significant number of patients. Fascial planes were preserved in involved muscles in over half of the patients, even in late-stage disease. Asymmetrical muscle involvement was seen with increasing frequency as the disease process increased in extent as evaluated by CT scanning. There was no discernible difference in the CT appearances in those patients who clinically had limb-girdle, facioscapulohumeral or scapuloperoneal distribution of weakness.

Muscle CT, biopsy and EMG in diagnosis of neuromuscular diseases

The diagnostic value of EMG and muscle biopsy has been compared with muscle CT in 53 patients with neuromuscular diseases. CT concordance with clinical diagnosis was found in 62% of myopathies and was highest in Duchenne PMD and scapulo-peroneal myopathy and very low in metabolic and inflammatory myopathies. In neurogenic diseases muscle CT agreed with clinical diagnosis in 63% of patients: the highest concordance was found in acquired polyneuropathies.

CT and the diagnosis of myopathies. Preliminary findings in 42 cases

A total of 42 patients with myopathies underwent CT scans in order to study the relationship between CT images and clinical findings. CT is a valuable diagnostic aid to distinguish primary from neurogenic myopathies, to facilitate directed biopsy and finally to classify the disease according to the degree and extent of the muscular lesion.

Atrophy of sacrospinal muscle groups in patients with chronic, diffusely radiating lumbar back pain

After surgery necessitated by lumbar back pain syndromes, radiolucency verified by CT may appear in the sacrospinal muscle group on the operated side. This radiolucency represents muscular atrophy and is in its most severe form a result of the replacement of muscle tissue with adipose tissue. Such muscular atrophy appeared in the present series in 31 out of all 156 patients (19.9%) and in 29 out of 94 patients operated on because of radiating lumbar back pain (30.9%). The radiological appearance, extent, and HU values of this muscular atrophy are presented in detail. Only weak correlations with the multitude of clinical symptoms and signs were found in this retrospective study. The effects of irreversible muscular atrophy on the indications for surgery and physiotherapy are discussed.