Work-Related Musculoskeletal Disorders Report, Workshop Summary, and Workshop Papers (1999) / Chapter Skim
Currently Skimming:
Biological Response of Peripheral Nerves to Loading: Pathophysiology of Nerve Compression Syndromes and Vibration Induced Neuropathy
Biological Response of Peripheral Nerves to Loading: Pathophysiology of Nerve Compression Syndromes and Vibration Induced Neuropathy
Pages 98-115
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 98... ...
Basic knowledge of the microanatomy of the peripheral nerve and the neuron and their complex reactions to compression are essential to understanding, preventing, and treating nerve compression 1nJurles. Structure and Ffunction of Peripheral Nerves Microanatomy The neuron consists of the nerve cell body which is located in the anterior horn of the spinal cord (motor neuron)
|
From page 99... ...
The normal propagation of impulses in the nerve fibers as well as the communication and nutritional transport system in the neuron - axonal transport - require a sufficient energy supply. ares · 1 1 .q ~ ~ · 1 1 1 1 1 · 1 ~ · ~1 ~ lithe peripheral nerve therefore contains a well developed m~crovascular system with vascular plexa in all connective tissue layers of the nerve (Lundborg ~ 970, 1 975~.
|
From page 100... ...
Experimental devices for nerve compression in animals Various methods have been used to induce an acute or chronic compression of a peripheral nerve in animal models. There are advantages and disadvantages with all used methods.
|
From page 101... ...
mmHg 20 30 40 50 80 150 500 1000 kPa 2.7 4.0 5.3 6.7 10.7 20.0 66.7 133.3 Nerve Compression - Acute Effects (Hours) Low-magnitude extraneural compression can decrease intraneural microvascular flow, impair axonal transport, and alter nerve structure and function in animal experiments.
|
From page 102... ...
. Static extraneural pressures of 4.0 kPa caused a decline in nerve function.
|
From page 103... ...
To model chronic nerve compression other investigators have placed short silicon tubes of~varying internal diameters or loose ligatures around the rat sciatic or sural nerve (Mackinnon et al. 1984' Mosconi et al.
|
From page 104... ...
Histology of Human Nerve Compression A biopsy of the nerve is likely to lead to permanent nerve dysfunction, therefore there are few human histologic studies of nerves at common sites of compression. In a few case reports (surgical resection of nerve, autopsy with known disease)
|
From page 105... ...
Animal models have been developed to evaluate the events taking place in peripheral nerves following vibration exposure. Acute vibration (82 Hz, peak-to-peak magnitude of 0.21 mm)
|
From page 106... ...
Such changes may occur to the meclian nerve in the carpal tunnel among people exposed to vibration. Nerve Excursion in Nerve Compression Syndromes Longitudinal gliding of the nerve trunk occurs normally during joint motions and has been measured using ultrasound in humans or with markers placed in the nerve in cadavers.
|
From page 107... ...
Significant findings: increasing wrist extension and to a lesser degree wrist flexion, increasing forearm supination, and increasing metacarpophalangeal deviation from 45 degrees flexion increase extraneural pressure in the carpal tunnel. Finger loading also increases carpal tunnel pressure in normal subjects and in cadavers.
|
From page 108... ...
Extraneural pressures in healthy humans performing repetitive tasks at the workplace are unknown. In a rat model, exposure of the hind limb to vibration for 4 to 5 hours per day for 5 days can cause intraneural edema, structural changes in myelinated and unmyelinated fibers in the sciatic nerve, as well as functional changes of both nerve fibers and non-neuronal cells.
|
From page 109... ...
Vibration induced neurophysiological and electron microscopical changes in rat peripheral nerves. Occup Environ Med ~ 994; 5 I: ~ 30- ~ 35.
|
From page 110... ...
Sensibility testing in peripheral nerve compression syndromes-A human experimental study in humans. ~ Bone loins Surg 1983; 65A:632 Gordon SL, Blair SI, Fine Ll (editors)
|
From page 111... ...
Dahlin LB: Anatomy, Function, and Pathophysiology of Peripheral Nerves and Nerve Compression. Hand Clinics 1996; 12~2~:~85-193.
|
From page 112... ...
Pathology of the flexor tendon sheath in the spontaneous carpal tunnel syndrome. ~ Hand Surg, British Volume, 1987; 12~2~:229-232.
|
From page 113... ...
Lundborg G Permeability of intraneural microvessels and perineurium following acute, graded experimental nerve compression.
|
From page 114... ...
Ultrastructural changes in peripheral nerves of the fingers of three vibration-exposed persons with Raynaud's phenomenon. Scand ~ Work Environ Health 1988; 14:31-35.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.