Autosomal dominant stapes ankylosis with broad thumbs and toes, hyperopia, and skeletal anomalies is caused by heterozygous nonsense and frameshift mutations in NOG, the gene encoding noggin.
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Although fixation of the stapes is usually progressive and secondary to otosclerosis, it may present congenitally, with other skeletal manifestations, as an autosomal dominant syndrome-such as proximal symphalangism (SYM1) or multiple-synostoses syndrome (SYNS1), both of which are caused by mutations in NOG, the gene encoding noggin. We describe a family that was ascertained to have nonsyndromic otosclerosis but was subsequently found to have a congenital stapes ankylosis syndrome that included hyperopia, a hemicylindrical nose, broad thumbs and great toes, and other minor skeletal anomalies but lacked symphalangism. A heterozygous nonsense NOG mutation-c.328C-->T (Q110X), predicted to truncate the latter half of the protein-was identified, and a heterozygous insertion in NOG-c.252-253insC, in which the frameshift is predicted to result in 96 novel amino acids before premature truncation-was identified in a previously described second family with a similar phenotype. In contrast to most NOG mutations that have been reported in kindreds with SYM1 and SYNS1, the mutations observed in these families with stapes ankylosis without symphalangism are predicted to disrupt the cysteine-rich C-terminal domain. These clinical and molecular findings suggest that (1) a broader range of conductive hearing-loss phenotypes are associated with NOG mutations than had previously been recognized, (2) patients with sporadic or familial nonsyndromic otosclerosis should be evaluated for mild features of this syndrome, and (3) NOG alterations should be considered in conductive hearing loss with subtle clinical and skeletal features, even in the absence of symphalangism. (+info)
Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. Plaster or functional splint in gamekeepers thumb.
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A short cut review was carried out to establish whether a plaster of Paris or functional splint was better for treatment of ulnar collateral ligament rupture. Altogether 50 papers were found using the reported search, of which one presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of this paper are tabulated. A clinical bottom line is stated. (+info)
Post-traumatic thumb reconstruction.
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Many options exist for the management of post-traumatic thumb reconstruction. While the single most important factor for determining the most appropriate procedure is the level of the amputation, many other factors must be considered including patient considerations regarding function and cosmesis as well as the nature of the injury and the expertise of the surgeon. Patients must be included in the decision-making process and their needs and expectations must be clearly defined and addressed. The patient who is most concerned with cosmesis rather than function is more likely to be satisfied with a prosthesis than with even the most cutting-edge surgical procedure. (+info)
Sources of signal-dependent noise during isometric force production.
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It has been proposed that the invariant kinematics observed during goal-directed movements result from reducing the consequences of signal-dependent noise (SDN) on motor output. The purpose of this study was to investigate the presence of SDN during isometric force production and determine how central and peripheral components contribute to this feature of motor control. Peripheral and central components were distinguished experimentally by comparing voluntary contractions to those elicited by electrical stimulation of the extensor pollicis longus muscle. To determine other factors of motor-unit physiology that may contribute to SDN, a model was constructed and its output compared with the empirical data. SDN was evident in voluntary isometric contractions as a linear scaling of force variability (SD) with respect to the mean force level. However, during electrically stimulated contractions to the same force levels, the variability remained constant over the same range of mean forces. When the subjects were asked to combine voluntary with stimulation-induced contractions, the linear scaling relationship between the SD and mean force returned. The modeling results highlight that much of the basic physiological organization of the motor-unit pool, such as range of twitch amplitudes and range of recruitment thresholds, biases force output to exhibit linearly scaled SDN. This is in contrast to the square root scaling of variability with mean force present in any individual motor-unit of the pool. Orderly recruitment by twitch amplitude was a necessary condition for producing linearly scaled SDN. Surprisingly, the scaling of SDN was independent of the variability of motoneuron firing and therefore by inference, independent of presynaptic noise in the motor command. We conclude that the linear scaling of SDN during voluntary isometric contractions is a natural by-product of the organization of the motor-unit pool that does not depend on signal-dependent noise in the motor command. Synaptic noise in the motor command and common drive, which give rise to the variability and synchronization of motoneuron spiking, determine the magnitude of the force variability at a given level of mean force output. (+info)
Somatotopic activation in the human trigeminal pain pathway.
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Functional magnetic resonance imaging was used to image pain-associated activity in three levels of the neuraxis: the medullary dorsal horn, thalamus, and primary somatosensory cortex. In nine subjects, noxious thermal stimuli (46 degrees C) were applied to the facial skin at sites within the three divisions of the trigeminal nerve (V1, V2, and V3) and also to the ipsilateral thumb. Anatomical and functional data were acquired to capture activation across the spinothalamocortical pathway in each individual. Significant activation was observed in the ipsilateral spinal trigeminal nucleus within the medulla and lower pons in response to at least one of the three facial stimuli in all applicable data sets. Activation from the three facial stimulation sites exhibited a somatotopic organization along the longitudinal (rostrocaudal) axis of the brain stem that was consistent with the classically described "onion skin" pattern of sensory deficits observed in patients after trigeminal tractotomy. In the thalamus, activation was observed in the contralateral side involving the ventroposteromedial and dorsomedial nuclei after stimulation of the face and in the ventroposterolateral and dorsomedial nuclei after stimulation of the thumb. Activation in the primary somatosensory cortex displayed a laminar sequence that resembled the trigeminal nucleus, with V2 more rostral, V1 caudal, and V3 medial, abutting the region of cortical activation observed for the thumb. These results represent the first simultaneous imaging of pain-associated activation at three levels of the neuraxis in individual subjects. This approach will be useful for exploring central correlates of plasticity in models of experimental and clinical pain. (+info)
Train-of-four nerve stimulation in the management of prolonged neuromuscular blockade following succinylcholine.
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Four patients, all possessing an atypical form of plasma cholinesterase, developed prolonged paralysis following succinylcholine administration. The clinical management of all four cases was facilitated by monitoring the train-of-four stimulus. All patients showed marked "fade" of the train-of-four ratio, the initial ratios of the fourth to the first twitches being 50 per cent or less, indicating variable degrees of nondepolarizing neuromuscular blockade. Reversal of paralysis with anticholinesterase agents was completely successful in three cases, but only partially effective in the fourth because of the probable presence of a mixture of both depolarizing block and nondepolarizing block. In such a situation, caution in the interpretation of the train-of-four ratio is necessary, since this test measures only the nondepolarizing component of the block. Whether or not reversal with anticholinesterase drugs is attempted, clinical estimates of neuromuscular function, such as head lift, vital capacity, and inspiratory force, must be carefully correlated with train-of-four values. If reversal is attempted, the brief action of edrophonium provides a useful clinical trial. (+info)
Shortening-induced depression of voluntary force in unfatigued and fatigued human adductor pollicis muscle.
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The goals of this study were to investigate adductor pollicis muscle (n = 7) force depression after maximal electrically stimulated and voluntarily activated isovelocity (19 and 306 degrees /s) shortening contractions and the effects of fatigue. After shortening contractions, redeveloped isometric force was significantly (P < 0.05) depressed relative to isometric force obtained without preceding shortening. For voluntarily and electrically stimulated contractions, relative force deficits respectively were (means +/- SE) 25.0 +/- 3.5 and 26.6 +/- 1.9% (19 degrees /s), 7.8 +/- 2.2 and 11.5 +/- 0.6% (306 degrees /s), and 23.9 +/- 4.4 and 31.6 +/- 4.7% (19 degrees /s fatigued). The relative force deficit was significantly smaller after fast compared with slow shortening contractions, whereas activation manner and fatigue did not significantly affect the deficit. It was concluded that in unfatigued and fatigued muscle the velocity-dependent relative force deficit was similar with maximal voluntary activation and electrical stimulation. These findings have important implications for experimental studies of force-velocity relationships. Moreover, if not accounted for in muscle models, they will contribute to differences observed between the predicted and the actually measured performance during in vivo locomotion. (+info)
True aneurysm of a thumb digital artery in a radiographer: a case report.
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True aneurysms of the digital artery are very rare. We report a case of true aneurysm of a proper digital artery of the right thumb in a radiographer. Treatment by ligation and excision resulted in complete relief of symptoms. (+info)