Muscle & nerve
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In the belief that changes in the adductor reflex (AR) may be helpful in evaluating lumbar root and plexus lesions, expression of the AR was studied in 43 healthy human subjects. ARs elicited with an electronic reflex hammer were recorded from the inner side of the proximal thigh using needle and surface electrodes, and patellar reflexes (PRs) were recorded simultaneously. These reflexes were obtained by tapping the ipsilateral medial aspect of the knee, the contralateral patellar tendon, the ipsilateral and contralateral anterior superior iliac spines, and the Achilles tendon. ⋯ By contrast, the PR could only be elicited by a tap to the ipsilateral patellar tendon. ARs have somewhat different features than other well-known tendon reflexes such as the PR and are recorded consistently when a needle electrode is used, being elicited from both distal and proximal areas of the legs by tapping the Achilles tendon or anterior superior iliac spines unilaterally or bilaterally. Their role in evaluating lumbar root disease and monitoring adductor spasticity merits investigation.
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Case Reports
Neoplastic lumbosacral radiculoplexopathy in prostate cancer by direct perineural spread: an unusual entity.
Neoplastic lumbosacral plexopathy occurs with some abdominal and pelvic malignancies. Patients present with severe pain radiating from the low back down to the lower extremities, and this progresses to weakness. ⋯ We describe two cases of lumbosacral radiculoplexopathy from infiltrative prostate cancer without evidence of other pelvic or extraprostatic spread. The probable etiology of tumor spreading along prostatic nerves into the lumbosacral plexus (i.e., perineural spread) is discussed as are the potential mechanisms for this unusual mode of cancer dissemination.
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Carbamates are reversible inhibitors of acetylcholinesterase, and some also inhibit neuropathy target esterase (NTE), the target in organophosphate-induced delayed polyneuropathy. However, based on mechanistic considerations, these carbamates were thought to be unable to initiate polyneuropathy. Consequently, clinical reports of polyneuropathy associated with carbamate exposures have been disregarded. ⋯ Alternatively, a preexisting subclinical neuropathy in these individuals may have been amplified by carbamates, as observed in animal models. We suggest that individuals with underlying neuropathy (e.g., diabetics) who are poisoned by carbamates should be followed closely. In addition, procedures for the current risk assessment of carbamate pesticides may need to be reconsidered.
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Excessive or extreme lengthening contractions have a well-characterized depressive effect on skeletal muscle isometric force. In addition to producing force, active muscles must often shorten in order to meet the power requirements of locomotion and other physical activities. However, the impact of lengthening contractions on muscle power is poorly understood. ⋯ Consequently, soleus peak power fell 37% after lengthening, a 2.5-fold greater decline than noted for the isometric treatment. Under the conditions studied here, the excessive power loss following lengthening contractions was due to force and velocity deficits of approximately equal relative magnitude. Because power represents the ability of the muscle to perform work, reductions in both force and shortening velocity should be considered when evaluating and treating lengthening-induced skeletal muscle injuries.