Muscle & nerve
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Clinical Trial
Intrathecal baclofen for spasticity-related pain in amyotrophic lateral sclerosis: efficacy and factors associated with pain relief.
Clinical signs and symptoms of spasticity include hypertonia, involuntary movements (spasms, clonus), decreased range of motion, contractures, and often spasm-related pain. When spasticity is refractory to medical management, patients may be referred for intrathecal baclofen (ITB) pump placement. We reviewed a cohort of amyotrophic lateral sclerosis (ALS) patients with intractable spasticity requiring ITB to further define the impact of ITB on pain relief in this patient population. ⋯ Six patients (75%) experienced pain score reduction, three of whom had complete pain relief. Postoperative pain reduction was predicted by the degree of pain reduction following preoperative ITB test injection. These results support ITB as a treatment modality for pain associated with spasticity in ALS.
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To test the hypothesis that the anterior horn cells become hypoexcitable in the absence of central drive, we recorded F waves simultaneously from the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM) before and after volitionally inactivating one muscle (target) while periodically contracting the other muscle (control). In 14 healthy subjects, F waves recorded from the target muscle showed a progressive decrease in persistence and amplitude (whether counting all 100 trials or only detectable responses) after muscle relaxation for 1, 3, and 6 hours, followed by a quick recovery upon brief muscle contraction. We conclude that volitional inactivation suppresses the F waves of the target muscle without equally affecting the control muscle innervated by the same nerve. The history of activity of a muscle should therefore be taken into account in clinical testing, especially when the study of a paretic muscle shows abnormal F-wave excitability.
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The effects of various exposures (intensity, duration) of high-intensity focused ultrasound (HIFU) on sciatic nerve conduction were investigated in vivo in rats. The objective was to identify HIFU exposures that produce biological effects ranging from partial to complete conduction block, indicating potential use of HIFU as an alternative to current clinical methods of inducing nerve conduction block. In the study, 26 nerves were exposed and treated with 5-s applications of 5.7-MHZ HIFU with acoustic intensities of 390, 2,255, 3,310, and 7,890 W/cm(2) (spatial peak, temporal peak). ⋯ For nerves treated with the three lower exposures, CMAPs decreased initially within 4 h or 7 days after HIFU treatment and then recovered to their baseline level at 28 days after treatment. For the highest exposure, however, CMAPs remained absent even 28 days after treatment. These exposure-dependent effects of HIFU on nerve function suggest its future potential as a novel treatment for severe spasticity and pain.
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In this prospective study, intraepidermal nerve fiber densities (IENFD) and subepidermal nerve plexus densities (SENPD) were quantified by immunostaining in skin punch biopsies from the distal calf in 99 patients with clinical symptoms of painful sensory neuropathy and from 37 age-matched healthy volunteers. The clinical diagnosis was based on history and abnormal thermal thresholds on quantitative sensory testing (QST). In patients with neuropathy, IENFD and SENPD were reduced to about 50% of controls. ⋯ For SENPD, sensitivity was 0.81 and specificity 0.88. With ROC analysis of both IENFD and SENPD together, the diagnostic sensitivity was further improved to 0.92. The combined examination of IENFD and SENPD is a highly sensitive and specific diagnostic tool in patients suspected to suffer from painful sensory neuropathies but with normal values on clinical neurophysiological studies.