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Tissue Response:Nerve: Page 7

Chambered Cuff Electrode.

Electrode was designed to form isolated chambers around the nerve to confine stimulus to restricted zones.

Nerve Injury with Cuff type Electrodes

Typically, investigators have reported no outward signs of nerve trauma. The concern is how to interpret these findings in relationship to safety of cuff type electrodes.
In the upper right panel is shown an image of a typical “crescent type region” It is characterized by having numerous thinly myelinated large axons, a loose axon packing density, interneural fibrous tissue, and subperineual thickening. Macrophages do not seem to be present in the “crescent type regions”. These “crescent type regions” are characteristically crescent in shape and positioned on a superficial region of the fascicle. In the panel on the lower right is a cross-section from a “normal” fascicle.
The most common type of mechanically induced injury is manifested as subperineurial crescents of endoneurial connective tissue. These areas of increased connective tissue were most frequently situated at the periphery of the fascicles and occasionally were accompanied by degenerating axons, localized axonal loss, and remyelinating axon profiles [8]. The subperineurial crescents may be adaptive to some degree since they closely resemble ‘Renaut bodies’ (hyaline-appearing, loosely-textured, whorled, cell-sparse structures found in the subperineurial space) [13]. Weis et al. [14] reported an association between the development of Renaut bodies and nerve entrapment, and proposed that these structures may serve as a pressure-absorbing cushion for entrapped nerve.


Agnew, W.F., and D.B. McCreery. "Principles of safe and effective nerve stimulation", In: New perspectives in sacral nerve stimulation, edited by U. Jonas, and V. Grunewald. London: Martin Dunitz, 2002, pp. 29-42

 

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