Rigid spine syndrome. A type I fiber myopathy

The rigid spine syndrome is an unusual disorder characterized by nonprogressive mild axial and proximal muscle weakness, flexion contractures of the neck and spine, scoliosis, and joint contractures. The biopsy specimen from the patient described in this report shows type I fiber hypotrophy and predominance. This contrasts with previous reports that describe connective tissue proliferation as the major histologic abnormality.

Reconstructive hand surgery in tetraplegia, stroke, and cerebral palsy: some basic concepts in physiology and neurology

The examination of hands in tetraplegia, stroke, and cerebral palsy must include evaluation of the state of the ligaments the muscles available for motors for tendon transfer, and, most important, the areas of sensibility. The test for two point discrimination is the most valuable in providing information regarding both exteroception and proprioception. Done properly, this test provides more useful information than any other used currently.

Pathophysiology of hyperkalemia induced by succinylcholine

SCh is unequivocally contraindicated in the management of patients who have sustainded thermal trauma or direct muscle trauma and those who have neurologic disorders involving motor deficits, including tetanus. The mechanism is clear in some, but not all, of these conditions, and is related to increased chemosensitivity of the muscle membrane due to the development of receptor sites in extrajunctional areas. Though SCh induces a small release of K+ in normal muscle, it produces a potentially lethal efflux in the presence of increased sensitivity. This K+-releasing action of SCh begins about 5 to 15 days after injury and persists for 2 to 3 months in patients who have sustained burns or trauma, and perhaps 3 to 6 months in patients with upper motor neuron lesions.

Connective tissue response to immobility. Correlative study of biomechanical and biochemical measurements of normal and immobilized rabbit knees

The biomechanical changes in rabbit knee contractures were measured after 9 weeks of immobilization. These results were correlated with the biochemical composition of periarticular connective knee tissue of the same knees. The loss of total hexosamine correlates significantly with joint stiffness on an animal-to-animal basis. Total hexosamine also correlates with the energy required cyclicly to flex and to extend the experimental joints. Of the individual glycosaminoglycan fractions, only hyaluronic acid showed significant correlation with the biomechanical data. The possible mechanism of contracture formation was postulated based on these results.

A forme fruste of the pterygium syndrome?

A case of a girl with popliteal webbing associated with limited extension of the knee, flexion contractures of the third, fourth, and fifth digits, hypothrophia of leg musculature, and absent tendon reflexes in the legs is reported. Between 19 months and 6 years of age, the digital contractures, popliteal webbing, and limitation of knee extension progressively improved. This is the first reported instance of this combination of signs and the first report of regression of some of these physical findings.

Twitch potentiation by potassium contractures in single muscle fibres of the frog

1. The modifications of isometric twitches after K contractures have been studied in single muscle fibres from frog muscles.2. The twitch was greatly enhanced and somewhat prolonged after a conditioning K contracture. This potentiating effect was more evident in fibres having low values of the ratio control twitch tension/tetanus tension (P/P(0)).3. In most of the fibres, the time course of the decay of the potentiation phenomenon could be represented by the sum of three negative exponentials with average half-times of 9.1, 40 and 485 sec.4. Between 3 and 10 min after the onset of the twitch potentiation the resting potential and action potential were unchanged.5. Mn blocked the K contractures and prevented the onset of the twitch potentiation.6. 40-140 sec after inducing a K contracture with 30 or 40 mM-K, a second exposure to the same [K] evoked a tension equivalent only to 57% of the first one. This partial refractoriness of the fibres is not seen when both contractures were elicited with 190 mM-K, and contrasts with the full recovery and potentiation of the twitch after a K contracture.

Biphasic potassium contractures in frog muscle fibers

Potassium-induced contractures were studied in single fibers from the semitendinosus muscle of Rana pipiens. Contractures elicited by solutions containing 60-117 mM potassium and 120 mM chloride were biphasic, consisting of a rapid initial contraction with a duration at 23 degrees C of less than 1 sec followed by a slow response with a duration of many seconds. At 13 degrees C, the initial response was greatly prolonged so that the two responses virtually fused into a single smooth contracture. Membrane potential in high potassium, high chloride solutions underwent a transient peak depolarization, probably as a result of time-dependent changes in membrane conductance during depolarization. It is proposed that this complex time course of depolarization gives rise to the biphasic contracture response.