Histological characteristics of sternoclavicular beta 2-microglobulin amyloidosis and clues for its histogenesis. (1/399)

BACKGROUND: The pathogenesis of beta 2-microglobulin amyloidosis (A beta 2m) has yet to be fully elucidated. METHODS: We describe the distribution and extent of A beta 2m deposition and macrophagic infiltration in cartilage, capsule, and synovium of sternoclavicular joints obtained postmortem from 54 patients after 3 to 244 (median 46) months of dialysis. Twenty-four nonuremic patients served as a control group. The diagnosis of amyloidosis (A) rested on a positive Congo Red staining (typical birefringence) and that of A beta 2m on positive immunostaining of the A deposits with a monoclonal anti-beta 2m antibody. The size of A deposits was measured. RESULTS: A beta 2m was detected in 32 (59%), and non-beta 2m amyloid (Anon beta 2m) was detected in an additional 8 (15%) of the 54 dialyzed patients. A beta 2m deposits were present in the cartilage of all A beta 2m (+) patients (100%). They were localized solely in the cartilage in 27% of the cases, either as a thin patchy layer or as a continuous thicker layer (identified as stage I). A beta 2m was additionally present in the capsule and/or synovium without macrophages in 27% of the cases (identified as stage II). The correlation between the size of cartilaginous deposits and dialysis duration (P = 0.02) as well as with the prevalence (P = 0.03) and size of capsular deposits (P = 0.02) suggests that stage II is a later stage of A deposition. Clusters of macrophages were detected around capsular and synovial amyloid deposits in 46% of the cases (identified as stage III). The longer duration of dialysis in those with stage III as well as the relationship between the size of the A beta 2m deposits and the prevalence of macrophagic infiltration suggests that stage III is the last stage of A beta 2m deposition. Marginal bone erosions were observed in 9 out of 12 patients with stage III deposits. Their size was correlated with that of cartilaginous deposits (P = 0.01). Among the 24 control patients, Anon beta 2m was detected in 12 patients (cartilage 100%, capsule 8%, synovium 30%). CONCLUSIONS: The earliest stage of A beta 2m deposition occurs in the cartilage. A beta 2m subsequently extends to capsule and synovium. These two first stages do not require macrophage infiltration. Macrophages are eventually recruited around larger synovial or capsular deposits in the final stage. Marginal bone erosions develop in this late stage.  (+info)

The prevalence and CT appearance of the levator claviculae muscle: a normal variant not to be mistaken for an abnormality. (2/399)

BACKGROUND AND PURPOSE: The levator claviculae muscle is an infrequently recognized variant in humans, occurring in 2% to 3% of the population, and has rarely been reported in the radiologic or anatomic literature. The importance of this muscle to radiologists is in distinguishing it from an abnormality; most commonly, cervical adenopathy. After discovering this muscle on the CT scans of two patients during routine clinical examinations, we conducted a study to determine the prevalence and appearance of the muscle on CT studies. METHODS: We evaluated 300 CT scans that adequately depicted the expected location of the muscle. The most superior level in which the muscle could be identified and the apparent location of insertion on the clavicle were recorded for all subjects in whom the muscle was detected. RESULTS: Seven levator claviculae muscles were identified in six subjects (2%). It was bilateral in one, on the left in four, and on the right in one. It was identified up to the level of the transverse process of C3 in all cases. The insertion was the middle third of the clavicle for two muscles and the lateral third of the clavicle for the remaining five muscles. CONCLUSION: Because the levator claviculae muscle will most likely be encountered during a radiologist's career, it is important to recognize this muscle as a variant and not as an abnormality.  (+info)

Cervical electromyographic activity during low-speed rear impact. (3/399)

Whiplash motion of the neck is characterized by having an extension-flexion motion of the neck. It has been previously assumed that muscles do not play a role in the injury. Eight healthy males were seated in a car seat mounted on a sled. The sled was accelerated by a spring mechanism. Muscle electromyographic (EMG) activity was measured by wire electrodes in semi-spinalis capitis, splenius capitis, and levator scapulae. Surface EMG activity was measured over trapezius and sternocleidomastoideus. Wavelet analysis was used to establish the onset of muscle activity with respect to sled movement. Shorter reaction times were found to be as low as 13.2 ms from head acceleration and 65.6 ms from sled acceleration. Thus the muscles could influence the injury pattern. It is of interest that clinical symptoms are often attributed to muscle tendon injuries.  (+info)

Effect of gaze on postural responses to neck proprioceptive and vestibular stimulation in humans. (4/399)

1. We studied the effect of gaze orientation on postural responses evoked by vibration of neck dorsal muscles or by galvanic stimulation of the vestibular system during quiet standing in healthy humans. Various gaze orientations were obtained by different combinations of horizontal head-on-feet (-90, -45, 0, 45, 90 deg) and eye-in-orbit (-30, 0, 30 deg) positions. The instantaneous centre of foot pressure was recorded with a force platform. 2. With a symmetrical position of the vibrator relative to the spine, neck muscle vibration elicited a body sway in the direction of the head naso-occipital axis when the eyes were aligned with it. The same result was obtained both during head rotations and when the head and trunk were rotated together. 3. For lateral eye deviations, the direction of the body sway was aligned with gaze orientation. The effect of gaze was present both with eyes open and eyes closed. After long-lasting (1 min) lateral fixation of the target the effect of gaze decreased significantly. 4. Postural responses to galvanic vestibular stimulation tended to occur orthogonal to the head naso-occipital axis (towards the anodal ear) but in eight of the 11 subjects the responses were also biased by the direction of gaze. 5. The prominent effect of gaze in reorienting automatic postural reactions indicates that both neck proprioceptive and vestibular stimuli are processed in the context of visual control of posture. The results point out the importance of a viewer-centred frame of reference for processing multisensory information.  (+info)

Intramuscular desmoid tumor (musculoaponeurotic fibromatosis) in two horses. (5/399)

Intramuscular desmoid tumors (musculoaponeurotic fibromatosis) were discovered in two young adult horses. The tumor in one horse was in the lateral cervical musculature, and that in the second horse occurred in the pectoral musculature. Histopathologic features were similar in both horses and included proliferation of fibroblasts and cells expressing muscle actin (myofibroblasts), with extensive dissecting fibrosis within muscle. These features are similar to those of desmoid tumors in humans, particularly those also known as musculoaponeurotic fibromatosis. Dissection of these lesions revealed a single central (horse No. 1) or multiple central (horse No. 2) fluid-filled cavities with associated sterile inflammation. The presence of these cavities supports the hypothesis that equine desmoid tumors are traumatic in origin, possibly occurring at sites of injections or bursal rupture. Surgical excision of the tumor in horse No. 1 was apparently curative, but the extent of the tumor in horse No. 2 precluded surgical excision.  (+info)

Use of a platysma myocutaneous flap for the reimplantation of a severed ear: experience with five cases. (6/399)

CONTEXT: The traumatic loss of an ear greatly affects the patient because of the severe aesthetic deformity it entails. The characteristic format of the ear, with a fine skin covering a thin and elastic cartilage, is not found anywhere else in the human body. Thus, to reconstruct an ear, the surgeon may try to imitate it by sculpting cartilage and covering it with skin. OBJECTIVE: To use a platysma myocutaneous flap for the reimplantation of a severed ear in humans. DESIGN: Case report. SETTING: Emergency unit of the university hospital, Faculty of Medicine, Ribeirao Preto - USP. CASE REPORT: Five cases are reported, with whole ear reimplantation in 3 of them and only segments in 2 cases. The surgical technique used was original and was based on the principle of auricular cartilage revascularization using the platysma muscle. We implanted traumatically severed auricular cartilage into the platysma muscle. The prefabricated ear was later transferred to its original site in the form of a myocutaneous-cartilaginous flap. Of the 5 cases treated using this technique, 4 were successful. In these 4 cases the reimplanted ears showed no short- or long-term problems, with an aesthetic result quite close to natural appearance. In one case there was necrosis of the entire flap, with total loss of the ear. The surgical technique described is simple and utilizes the severed ear of the patient. Its application is excellent for skin losses in the auricular region or for the ear itself, thus obviating the need for microsurgery or the use of protheses or grafts.  (+info)

Differences in expression of acetylcholinesterase and collagen Q control the distribution and oligomerization of the collagen-tailed forms in fast and slow muscles. (7/399)

The collagen-tailed forms of acetylcholinesterase (AChE) are accumulated at mammalian neuromuscular junctions. The A(4), A(8), and A(12) forms are expressed differently in the rat fast and slow muscles; the sternomastoid muscle contains essentially the A(12) form at end plates, whereas the soleus muscle also contains extrajunctional A(4) and A(8) forms. We show that collagen Q (ColQ) transcripts become exclusively junctional in the adult sternomastoid but remain uniformly expressed in the soleus. By coinjecting Xenopus oocytes with AChE(T) and ColQ mRNAs, we reproduced the muscle patterns of collagen-tailed forms. The soleus contains transcripts ColQ1 and ColQ1a, whereas the sternomastoid only contains ColQ1a. Collagen-tailed AChE represents the first evidence that synaptic components involved in cholinergic transmission may be differently regulated in fast and slow muscles.  (+info)

Frequency analysis of EMG activity in patients with idiopathic torticollis. (8/399)

The pathophysiology of idiopathic dystonic torticollis is unclear and there is no simple test that confirms the diagnosis and excludes a psychogenic or voluntary torticollis in individual patients. We recorded EMG activity in the sternocleidomastoid (SCM) and splenius capitis (SPL) muscles of eight patients with rotational torticollis and eight age-matched controls, and analysed the signals in the frequency and time domains. All control subjects but one showed a significant peak in the autospectrum of the SPL EMG at 10-12 Hz, which was absent in all patients with torticollis. Conversely, patients with torticollis had evidence of a 4-7 Hz drive to the SPL and SCM that was absent in coherence spectra from controls. The pooled cumulant density estimates revealed a peak in both groups, and within the patient group there was a second narrow subpeak with a width of 13 ms. The activity in the SCM and SPL was in phase in the patients but not in the controls. The lack of any phase difference and the suggestion of short-term synchronization between SCM and SPL are consistent with an abnormal corticoreticular and corticospinal drive in dystonic torticollis. Clinically, the pattern of SPL EMG autospectra and of SCM-SPL coherence may provide a sensitive and specific feature distinguishing dystonic from psychogenic torticollis.  (+info)