Cross section of nerve where a spiral cuff had been implanted for seven months (top). Empty outer area is where the cuff had been. Narrow layer of encapsulation tissue can be seen around the nerve and the cuff.
In the lower right, a cross section of a nerve with two wraps of a spiral cuff around it is shown.

CNR: Cuff to Nerve Ratio is shown at top of the table.
At 7 to 11 Months after implantation , no detectable impairment were detected.
" Type-1 response." - These nerves exhibit the thin myelin that is associated with axonal regeneration and remyelination.
“ Type-2 response” - Axonal swelling and distension were also observed. Distended axons generally show an extremely thin myelin sheath whereas regenerated or remyelinated axons show a reduced, but still substantial sheath. The density and distribution of myelinated axons appears normal in these nerves.
“ Type-3 response”- If no apparent loss of myelinated axon density was found at the distal level, the effect at the cuff level most likely due to Schwann cell proliferation rather than to axonal loss. Nerves with an apparent low myelinated axon density at the cuff level but none at the distal level.
“ Type -4 response” - Nerves that exhibit an apparent low myelinated axon density at both the cuff and distal levels.
Conclusion - insult was random and could not be attributed to CNR- most likely due to the implant procedure.