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Biomedical subjects

E R Hackett

Publications and source records attributed to E R Hackett.

At least 19 recordsLinked to original sources
PubMed1998

Methylene blue.

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Central Nervous System↗
PubMed1986

Surgery for lesions of the brachial plexus.

Current diagnostic workup and surgical management of stretch injuries, gunshot wounds, lacerations, iatrogenic injuries, tumors, and thoracic outlet syndromes involving the brachial plexus are reviewed. Use of appropriate radiologic and electrodiagnostic studies to work up such patients is summarized as is selected literature concerning the more controversial aspects of their management. Some of the arguments both for and against operation on stretch injuries are presented and it is concluded that surgery can be of value for well-selected patients. Although a number of patients with gunshot wounds involving the plexus recover spontaneously, many still require an operation. Experience with tumors arising from the plexus suggests the need for early and relatively aggressive removal. Use of magnification and intraoperative recording permits removal of some but not all neurofibromas without further deficit. Timing for repair of lacerating injuries to the plexus, as well as iatrogenic injuries, selection of the few patients with thoracic outlet syndrome who require operation, and a brief review of plexus neuropathy are also presented. Importance of evaluating individual plexus injuries in terms of how complete or incomplete loss is in the distribution of each individual element is stressed. Development of intraoperative stimulation and recording methods to help sort out lesions, use of magnification for repair, and improved grafting techniques where gaps result from resection have helped to restimulate interest in managing these patients.

Action Potentials↗
PubMed1975

Progression of partial experimental injury to peripheral nerve. Part 1: Periodic measurements of muscle contraction strength.

Isometric measurements of muscle contraction in response to single as well as tetanic volleys of supramaximal stimuli were recorded from the limbs of 32 monkeys with noninjured or partially lacerated tibial nerves. Nerve action potentials (NAP) and muscle action potentials (MAP) were also determined at intervals varying from 1 hour to 52 weeks after injury. Limbs with mobilized noninjured nerve sustained small but definite decreases in muscle contraction strength particularly if the interval between operations was brief. Partially lacerated nerves had immediate averaged decreases in single twitch and supramaximal contraction strengths of 32.8% and 30.4% despite maintenance of NAP velocity. One week following injury, muscle contraction had decreased by another 21.6% and 19.7% respectively while NAP velocity was decreased by 18.5%. Measurements were also reduced at 2, 4, and 8 weeks and to a lesser degree at 12 weeks; at 24 and 36 weeks, muscle contraction was less than pre-injury data but not when compared to recordings 15 minutes after injury. Values recorded at 52 weeks reflected partial reinnervation of Achilles musculature. Studies over a 24-hour period following partial laceration demonstrated significant further decreases in muscle power by 8 hours. The authors conclude that nerve activity following partial laceration fluctuates as function diminishes during the early hours to weeks following injury.

Action Potentials↗
PubMed1975

Reappraisal of timing for exploration of civilian peripheral nerve injuries.

Operative as well as electrophysiologic experience with 213 major nerve injuries over the last 8 years and primate experiments form the basis of this reappraisal. Those lesions in continuity resected (58 of 172) usually had no response to stimulation or nerve action potential (NAP) at 8 weeks or longer after injury but were not necessarily complete lesions on clinical examination or electromyography. Axonal organization and maturity were of such poor quality that functional regeneration would not have resulted. Despite preoperative evidence of an incomplete lesion, operative studies confirmed a complete lesion in 21 instances. In 103 lesions NAP's could be recorded and, where neurolysis was done, recovery was acceptable in 91 percent. Many of these lesions had appeared complete on preoperative evaluation. Nerves transected by glass and repaired primarily had superior electrical and functional recovery to those repaired secondarily, although variations in clinical settings prevented statistical analysis. Experimental work in 20 primates with glass-wounded nerves favored primary repair, for NAP, evoked muscle action potential, and strain gauge studies of muscle power were superior in 14. Lesions in continuity should have exploration delayed until 8 weeks so that physiologic decisions regarding need for resection and repair can be made. Transecting injuries should be explored primarily, those without contusinve element repaired immediately, and those with contusion repaired 3 weeks after injury.

Action Potentials↗