The myositides: the role of imaging in diagnosis and treatment.

The entities encompassing the syndromes collectively known as myopathies and myositis are composed of numerous separate and distinct disorders with a vast spectrum of clinical signs, symptoms, immunopathology, genetic and environmental influences, as well as overall clinical outcome. Classification of the myositides (diseases of skeletal muscle) remains a rather controversial subject due to our lack of complete understanding of this divergent group of disorders. The mainstay of achieving diagnosis of a myopathy has until relatively recently been with a combination of clinical acumen, laboratory assessment, electromyography, and muscle biopsy. The use of modern high-resolution cross-sectional imaging studies is of particular value in confirming the physical findings and identifying suitable sites for biopsy. Imaging is fast becoming an established part of the overall evaluation of myopathies and myositis, helping to delineate the location and extent of the disease process, and it is being recognized as central to a prompt and accurate diagnosis in some cases. Although radiology has mainly been seen to have a subsidiary role in the diagnosis of myositides, newer imaging techniques following recent determined research interests have began to spark a renewed interest in the complex field of skeletal muscle imaging.

Acquired cavo-varus deformity caused by an accessory calcaneus: a case report and literature review.

We describe an unusual cause of an acquired cavo-varus foot deformity produced by progressive enlargement of an accessory calcaneal ossicle. A 13-year-old boy with constitutional plano-valgus flat feet noted a gradual change in foot shape associated with lateral ankle pain on ambulation following an inversion injury 2 years earlier. CT and MRI scans confirmed a large accessory calcaneal ossicle lying within the sinus tarsi, with associated marrow oedema. Following surgical excision of the ossicle, the foot returned to its original shape and the symptoms were alleviated. This is the fifth reported case of an accessory calcaneal ossicle, but the only case that has occurred in a flatfooted individual. We also present the first reported MRI images of the lesion confirming pathological marrow oedema as a response to mechanical stress.

Os peroneum friction syndrome complicated by sesamoid fatigue fracture: a new radiological diagnosis? Case report and literature review.

Injuries to the peroneal tendons are relatively common worldwide but tendon rupture without significant trauma is uncommon. Ankle mechanics can be seriously affected by disruption of one or both of the peroneal tendons although complete rupture can also remain asymptomatic. Accessory ossicles are sesamoid bones and are common findings in routine radiology of the foot and ankle. Although in the vast majority these "os" are normal variants of anatomy, they can lead to painful syndromes and suffer fractures and even undergo degenerative changes in response to overuse and trauma. Although similar syndromes have been discussed in the surgical literature, there is a lack of literature describing the use of modern imaging in the accurate diagnosis and its subsequent assistance towards appropriate management of os peroneum friction syndrome complicated by sesamoid fatigue syndrome. This article presents the plain film, sonographic and magnetic resonance imaging findings in a case of os peroneum friction syndrome complicated by a sesamoid fatigue fracture as well as reviewing the pertinent literature.

Imaging of entrapment and compressive neuropathies.

Although the subject of entrapment and compressive neuropathies is huge, with dedicated textbooks on the subject, this article attempts to provide an up-to-date overview of the role of imaging in the diagnosis of nerve entrapment and compression syndromes. Entrapment and compressive neuropathies are a group of distinct syndromes secondary to physical constriction or irritation affecting peripheral nerves at specific anatomical sites in the body. Most nerve entrapment and compressive syndromes derive from an injury to the neurovascular components in a narrow anatomical passage. Because of their etiological diversity, which includes pressure, angulation, stretch, and friction, the pathophysiology of individual nerve entrapment syndromes differs widely. Neuropathy can result in considerable morbidity. Although the mainstay of achieving diagnosis is with clinical acumen and electrophysiological investigations, the increasing use of modern high-resolution imaging studies is of particular value in confirming physical findings and enabling determination of the extent of injury. Knowledge and familiarity of pertinent anatomy and appropriate choice of imaging modality is important for the radiologist to allow accurate interpretation of site and etiology of nerve entrapment and compression as well as ascertaining possible alternative diagnoses.

Postural changes of the dural sac in the lumbar spines of asymptomatic individuals using positional stand-up magnetic resonance imaging.

STUDY DESIGN: Positional magnetic resonance imaging (MRI) study of control subjects. OBJECTIVES: To determine dimensional changes in the lumbar dural sac as a function of posture, and to establish changes between the supine, erect and seated positions. SUMMARY OF BACKGROUND DATA: Studies using computerized tomography and MRI were done to determine the mechanical effects on the lumbar spinal canal in the different positions. There has been no consecutive study, however, in which normal individuals were investigated for positional changes of the dural sac, including true standing position. METHODS: Thirty-two male asymptomatic volunteers were recruited. The examination was performed using a new MRI system. All subjects were examined with sagittal T2 and axial T1-weighted spin-echo images. The subjects were studied in the supine, standing, and sitting positions. The measurements were made using OSIRIS software (Digital Imaging Unit University Hospital of Geneva, Geneva, Switzerland). On axial images, dural sac cross-sectional area and anteroposterior (AP) dural sac diameter were measured at the level of the L3/4, L4/5, and L5/S1 discs. On midsagittal images, AP dural sac diameter and the upper-endplate angles of L1 and S1 were measured. RESULTS: We found a disc degeneration or disc protrusion in 41% (12/29) of the subjects, but there was no obvious compression of the dural sac. Depending on the postures, the mean dural sac cross-sectional area and AP dural sac diameter changed. At all levels, mean dural sac cross-sectional area in the supine position was significantly smaller than in other postures. The dural area decreased most at the L5/S1 level due to positional change from standing to supine. The largest dural area at the L5/S1 level was in sitting extended. AP dural sac diameter on axial and midsagittal images showed a similar tendency. CONCLUSIONS: A significant posture-dependent difference of the dural sac cross-sectional area at the level of intervertebral disc in asymptomatic volunteers has been demonstrated. When the posture changed from supine to standing position, lumbar dural sac volume expanded by the increased pressure of cerebrospinal fluid, and the dural sac cross-sectional area increased. The smallest values were found in the supine position.