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Biomedical subjects

R W Gilliatt

Publications and source records attributed to R W Gilliatt.

At least 55 records · Page 3Linked to original sources
PubMed1972

Nerve conduction during Wallerian degeneration in the baloon.

Conduction in the lateral popliteal nerve of the baboon was studied during the course of Wallerian degeneration. Six nerves were examined. In each case the muscle response to nerve stimulation and the ascending nerve action potential were recorded daily until the nerve became inexcitable. The muscle response to nerve stimulation disappeared after four to five days, but ascending nerve action potentials could be recorded for a further two to three days. There was no change in maximal motor conduction velocity or in distal latency until the muscle response to nerve stimulation was severely reduced in amplitude. At this stage there was a consistent increase in distal latency, sometimes associated with a mild reduction in maximal motor velocity in the leg. There was no change in the velocity of ascending nerve action potentials. Histological studies confirmed the presence of degeneration in the terminal parts of the intramuscular nerve fibres at a time when the proximal parts of the same fibres were relatively normal.

Action Potentials↗
PubMed1972

Recovery of nerve conduction after a pneumatic tourniquet: observations on the hind-limb of the baboon.

A small pneumatic cuff inflated around the knee was used to produce tourniquet paralysis in baboons. A cuff pressure of 1,000 mm Hg maintained for one to three hours produced paralysis of distal muscles lasting up to three months. Nerve conduction studies showed that most of the motor fibres to the abductor hallucis muscle were blocked at the level of the cuff and that they conducted impulses normally in their distal parts. There was a significant correlation between the duration of compression and that of the subsequent conduction block. When tested two to three weeks after the tourniquet, the amplitude of the response of m. abductor hallucis to nerve stimulation distal to the cuff was usually slightly reduced compared with the precompression figure. This was assumed to mean that a small proportion of the motor fibres had undergone Wallerian degeneration as a result of compression. Maximal motor conduction velocity was reduced in recovering nerves. It was also reduced when a cuff pressure of 500 mm Hg was used, which was insufficient to produce persistent conduction block. In such cases a reduced velocity without evidence of block could be demonstrated 24 hours after compression. Ascending nerve action potentials were recorded from the sciatic nerve in the thigh, with stimulation at the ankle. Before compression the fastest afferent fibres had a significantly higher velocity than the fastest motor fibres in the same nerve trunk. Results after compression suggested that the high-velocity afferent fibres had a susceptibililty to the procedure similar to that of the fastest motor fibres.

Action Potentials↗
PubMed1971

Motor and sensory nerve conduction velocity in the baboon: normal values and changes during acrylamide neuropathy.

Nerve conduction velocity and the amplitude of nerve and muscle action potentials have been measured in the median and anterior tibial nerves of normal adult and infant baboons. The effect of altered temperature on velocity has also been investigated. Seven adult baboons were intoxicated with acrylamide. In animals given 10-15 mg/kg/day, the gradual development of a peripheral neuropathy was accompanied by a decline in the amplitude of both muscle and nerve action potentials. There was also a gradual fall in conduction velocity. In some cases maximal motor velocity in the median nerve fell by as much as 34%, and in the anterior tibial nerve by as much as 49%, the largest falls being seen in animals showing the greatest reductions in response amplitude. Histological studies, reported elsewhere, have shown that the main pathological change in our animals was a degeneration of the peripheral nerves, with little demyelination. Fibre diameter histograms indicated that large fibres were particularly severely affected, and it seems likely that the reduced maximal conduction velocities were due to this selective loss of large-diameter fibres.

Acrylamides↗
PubMed1970

Wasting of the hand associated with a cervical rib or band.

Nine patients are described with unilateral wasting of the hand muscles associated with elongated C7 transverse processes or with rudimentary cervical ribs. In three patients there was selective wasting of the lateral part of the thenar pad, accompanied by mild weakness of the other hand muscles. In four patients all the hand muscles were wasted, but this was more marked in the lateral part of the thenar pad than elsewhere. In two patients wasting was uniformly distributed throughout the hand. Weakness and wasting in the forearm was only present in four patients and was relatively mild. Sensory loss, when present, affected mainly the inner side of the forearm. Nerve conduction studies revealed no abnormality in the distal part of the median nerve, but some patients had reduced or absent sensory action potentials when the fifth finger was stimulated. In all nine patients a sharp fibrous band was found at operation, which extended from an elongated C7 transverse process or from a rudimentary cervical rib to the region of the scalene tubercle on the first rib. The fibrous band caused angulation of the C8 and T1 roots in five patients, and of the lower trunk of the brachial plexus in three. Pathological changes were frequently visible in affected nerves at the site of angulation. Division of the fibrous band relieved pain and paraesthesiae in eight patients and arrested muscle wasting and weakness in nine patients. There was, however, only slight recovery of power in affected muscles; wasting in the hand appeared to be unchanged after periods of up to eight years.

Action Potentials↗
PubMedDate not supplied

Sensory conduction studies in the early recognition of nerve disorders.

Early investigations into sensory conduction are reviewed and related to recent and ongoing research, specifically with relation to the early detection of nerve disorders. Current study on entrapment neuropathies and on the assessment of minor sensory conduction changes is presented. It is concluded that, in the early recognition of nerve disease, the clinical orientation of the electromyographer is essential to proper test interpretation.

Electrodiagnosis↗
PubMedDate not supplied

F waves in patients with hand wasting caused by a cervical rib and band.

In five patients with unilateral wasting of the hand muscles as a result of cervical rib and band, F waves were recorded from the hypothenar muscles following stimulation of the ulnar nerve at the wrist. Twelve healthy control subjects were also examined. F-wave latency was consistently increased in the affected hands of the patients, compared with results from the unaffected and control hands. This increase persisted after removal of the cervical band in four patients and was thought to be mainly due to degeneration of fast-conducting fibers. In the fifth patient, F-wave latency decreased after operation, suggesting recovery of a local conduction block in the proximal part of the nerve.

Action Potentials↗
PubMedDate not supplied

Supernormal excitability of human sensory fibers after ischemia.

Weak electrical stimuli were applied to sensory fibers of the median nerve at the wrist, and the ascending action potentials were recorded at the elbow. This was done with or without a preceding conditioning stimulus to test for supernormal excitability to the second stimulus. In the resting nerve, supernormal excitability was present from 3 to 20 msec after a conditioning shock. After a period of ischemia, excitability was both exaggerated and prolonged. This observations confirms the presence in sensory fibers of a phenomenon previously described in motor fibers.

Action Potentials↗
PubMedDate not supplied

Conduction velocity and conduction block after experimental ischaemic nerve injury.

The effect of ischaemic nerve injury on conduction in the tibial branch of the sciatic nerve has been studied in rabbits. Ischaemic nerve damage wa produced in 40 animals by ligation of the common and external or the internal and external iliac arteries. Conduction in the motor fibres to the small foot muscles was examined at internals after operation, with nerve stimulation in the thigh and at the ankle. Ascending nerve action potentials in the tibial nerve were also studied. In 8 animals there was evidence o widespread degeneration of myelinated fibres; muscle action potentials could not be activated by nerve stimulation nerve action potentials were absent. In contrast there were 14 animals in which arterial ligation appeared to produce little, if any, nerve degeneration; in this group there was no significant change in motor or afferent velocity. The remaining 18 animals showed changes of intermediate severity. While nerve degeneration was extensive, it was never complete, and in 9 nerves examined 5 - 11 days after surgery, conduction block between the thigh and ankle could be demonstrated in surviving fibres. In the other 9 nerves there was no block in surviving fibres but maximal motor velocity was significantly reduced. In no case did the conduction block affect more than a minority of the motor fibres, the remainder undergoing complete degeneration. This was in keeping with the histological appearances which showed a relatively small amount of paranodal and segmental demyelination compared with the amount of Wallerian degeneration.

Action Potentials↗