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Biomedical subjects

T R Swift

Publications and source records attributed to T R Swift.

At least 37 records · Page 2Linked to original sources
PubMed1988

Growth of skeletal muscle from patients with amyotrophic lateral sclerosis transplanted into nude mice.

We studied the fate of skeletal muscle obtained from patients with amyotrophic lateral sclerosis (ALS) after transplantation into immunodeficient nude mice. The transplanted muscle consistently survived in the nude mice without immunological rejection. The myofibers in these muscles underwent degeneration, followed by regeneration, maturation, and eventual functional innervation by the mouse motor neurons. The ability to grow diseased human muscle successfully over a prolonged period in nude mice offers an in vivo model to study the etiology of ALS and possibly of other neuromuscular disorders.

Aged↗
PubMed1987

Ice pack test for myasthenia gravis.

A common symptom of myasthenia gravis is eyelid ptosis. Often, the edrophonium test is negative, particularly in ocular myasthenia gravis. Myasthenic weakness is often improved by cold. We applied ice packs to the eye in 10 myasthenic patients and 7 disease controls. Eight of 10 patients with myasthenia gravis improved, whereas none of the controls improved. The ice pack test is useful in the diagnosis of myasthenia gravis.

Adolescent↗
PubMed1986

Dural sarcoidosis presenting with transient neurologic symptoms.

Despite the propensity of sarcoid granulomas to be clustered around blood vessels, transient ischemic attacks and strokes are rare. A 43-year-old man had recurrent transient dysarthria and right hemiparesis; a biopsy specimen showed neurosarcoidosis. There was complete resolution of both symptomatology and the subdural sarcoid mass lesion with the administration of corticosteroid therapy.

Adult↗
PubMed1986

Increased motor neuron projection during development does not increase the number of neuromuscular synapses.

We investigated in developing embryos whether the total number of neuromuscular synapses is determined by the muscle or by the number of innervating motor neurons. The superior oblique muscle of duck embryos was hyperinnervated by preventing the naturally occurring death of trochlear motor neurons using immunoglobulin G from patients with acquired myasthenia gravis. In spite of a significant increase in the number of motor neurons innervating the muscle, a corresponding increase in the number of neuromuscular synapses did not occur. These results suggest that the total number of synapses in a muscle is independent of the number of innervating motor neurons and that it is determined intrinsically by the muscle itself.

Animals↗
PubMed1984

The droopy shoulder syndrome.

We found that patients with thoracic outlet syndrome have: (1) low-set, "droopy" shoulders and long swan neck; (2) pain in the neck, shoulder, chest, arms, or hands; (3) aggravation of symptoms by downward traction and relief by propping up the arms; (4) occurrence in women; (5) absence of abnormal vascular, neurologic, and electrical findings; (6) a Tinel's sign over the brachial plexus; and (7) T-2 vertebra visible above the shoulders on lateral cervical spine films. In our experience, droopy shoulder syndrome has accounted for most cases of thoracic outlet syndrome but is largely unrecognized by physicians. Recognition of this syndrome should lead to a better understanding of the underlying pathophysiology and prevent unnecessary surgery.

Adult↗
PubMed1984

Tinnitus from intracranial hypertension.

Five patients had unilateral tinnitus from increased intracranial pressure of different etiologies. In each case, the tinnitus was produced by a venous bruit and could be decreased by Valsalva's maneuver, head turning to the ipsilateral side, or by light pressure over the ipsilateral jugular vein. Correction of the increased intracranial pressure obliterated the tinnitus. Turbulence, created as blood flows from the hypertensive intracranial portion into the low pressure of the jugular bulb, is proposed as the mechanism producing the tinnitus.

Adult↗
PubMed1983

Myasthenia gravis immunoglobulin augments motor neuron survival without producing muscle paralysis.

Effects of sera or immunoglobulins from patients with acquired myasthenia gravis on motor neuron survival during critical stages of embryonic development were investigated in the trochlear nucleus-superior oblique muscle system of white Peking duck embryos. A significant increase in motor neuron survival occurred following application of myasthenia gravis sera or myasthenic immunoglobulin during the period of embryonic death of motor neurons. There was no reduction in limb or extraocular muscle movement in treated embryos. Trochlear motor neuron survival persisted after sera or immunoglobulin treatment was discontinued. The total number of muscle fibers and acetylcholine receptors were unchanged following immunoglobulin treatment. Myasthenic immunoglobulin is therefore unique in preventing motor neuron death without producing muscle paralysis and in promoting a prolonged augmentation of motor neuron survival. It is concluded that factors other than muscle activity may also control neuron survival during embryogenesis. Previous studies of myasthenic sera in muscle have shown effects only postsynaptically. This is the first demonstration that myasthenic immunoglobulin affects structures in the central nervous system.

Animals↗
PubMed1982

Effect of height on nerve conduction velocity.

The effect of height on nerve conduction velocity (NCV) was studied in 41 normal subjects. Peroneal and sural NCV correlated inversely with height and with estimated axonal length, whereas median motor and sensory NCV failed to show any significant relationship to height. These findings are consistent with the hypothesis of abrupt distal axonal tapering in the lower extremities. Recognition of height effect in the legs is clinically significant, since diagnostic sensitivity of NCV determinations is improved when corrected for height differences. Multiple regression equations derived from the sample data allow satisfactory estimation of peroneal NCV, sural NCV, H-reflex latency, and F-wave latency from height (or axonal length), age, and other important predictors.

Adult↗
PubMed1981

Differential diagnosis of acute weakness.

Muscle weakness evolving rapidly over hours to days demands prompt diagnosis and proper treatment to prevent life-threatening respiratory insufficiency. Such weakness usually results from disease affecting some portion of the motor unit, such as poliomyelitis, Guillain-Barré syndrome, botulism, and dyskalemic myopathy. The differential diagnosis of these processes is discussed.

Botulism↗
PubMed1981

Peripheral neuropathy in epileptic patients.

The prevalence of peripheral neuropathy in 186 epileptic patients was 16.7%. The neuropathy was characterized by stocking hypesthesia and reduced Achilles reflexes, and it occurred with all anticonvulsant agents. Electrophysiologic tests indicated slowing of peroneal and sural nerve conduction velocity and prolongation or absence of H reflexes and F responses. The prevalence of neuropathy was not greater in patients receiving phenytoin, and there was no relationship between clinical or electrical abnormalities and blood levels or duration of treatment for either phenytoin or phenobarbital. We did not find a specific relationship between phenytoin usage and peripheral neuropathy in epileptic patients.

Epilepsy↗
PubMed1980

Myelopathy in mucopolysaccharidosis type II (Hunter syndrome).

A 24-year-old man with Hunter syndrome had spastic quadriparesis due to impingement of thickened meninges upon the cervical spinal cord. Tracheal narrowing due to submucosal deposits (presumably mucopolysaccharide) produced serious ventilatory complications during induction of anesthesia and necessitated tracheostomy before surgical decompression of the spinal cord could be attempted. Recognition of compressive myelopathy and tracheal compromise as late complications of Hunter syndrome may promote early therapy and prevent respiratory catastrophe.

Adult↗
PubMed1980

Plasma exchange in myasthenia gravis: electrophysiological studies.

Electrophysiological recordings of evoked muscle action potentials during repetitive stimulation were performed in four female patients undergoing plasmapheresis for myasthenia gravis. Studies were done immediately before and after each exchange and were repeated daily during a series of exchanges and at intervals thereafter. Electrophysiological improvement was seen but was delayed for at least seven days from the start of plasmapheresis therapy. No sudden and substantial improvements were encountered, though anti-receptor antibody titers dropped precipitously. A reversible neuromuscular blocking effect of anti-receptor antibody could not be demonstrated in these patients.

Antibodies↗
PubMed1980

Centric relation: a comparison of muscle-determined position and operator guidance.

Fifteen subjects were used to determine direction and magnitudes of shifts in condylar position when interocclusal records were made by biting hard or easy on a leaf gauge or wax. Electromyographic recordings were made of the temporal and masseter muscles during interocclusal registrations to determine which muscles were most active in seating the condyle when the leaf gauge was used. Results indicated no significant difference in condylar position superoinferiorly between registrations. Biting hard on a leaf gauge caused a significantly more posterior position of the condyle. When this technique is used for obtaining interocclusal registrations, the temporal muscles are more active than the masseters.

Adult↗
PubMed1980

Arm-diaphragm synkinesis: electrodiagnostic studies of aberrant regeneration of phrenic motor neurons.

Arm-diaphragm synkinesis may occur after injury to the proximal portion of the brachial plexus or cervical nerve roots. Regenerating axons of phrenic motor neurons are misdirected to supply limb muscles. Electrodiagnostic investigations of three patients with symptoms referable to upper brachial plexus or cervical roots revealed motor units in either biceps or triceps muscles that discharged during inspiration. These units did not fire during forced or passive expiration or Valsalva maneuver. Activation of these units could not be achieved by volitional contraction of the appropriate arm muscles. The synkinetic motor units were of increased amplitude and duration. Some units contained late components that demonstrated jitter and blocking, as is characteristic of reinnervated motor units. The unwary electromyographer may misinterpret these synkinetic units as incomplete muscle relaxation or some form of abnormal repetitive discharge. Correct identification of these units provides objective evidence of antecedent nerve root or brachial plexus injury.

Adult↗
PubMed1979

Ethylene oxide neurotoxicity: report of four cases and review of the literature.

Four workers were exposed to ethylene oxide gas. Acute encephalopathy occurred in one, and peripheral neuropathy in three, two of whom were symptomatic. Nerve conduction velocity studies were abnormal in three, including the asymptomatic patient. Decreasing the amount of exposure resulted in relief of symptoms. The abnormal nerve conduction studies did not change in two patients who continued to work at a lower level of exposure, whereas the conduction abnormalities improved in the patient who was removed from exposure.

Adult↗