Histological reaction to percutaneous epidural neurostimulation: initial and long-term results.

Percutaneously inserted spinal epidural neurostimulation has been derived as a simplified safe alternative to surgically implanted, dorsal column stimulation that is used in the effective treatment and control of spasticity and intractable pain. Twenty-seven tissue specimens from fifteen patients having had percutaneous epidural neurostimulation systems implanted were studied with the aid of light microscopy. The biopsies from tissues around the cables, around the receivers, and at the actual site of epidural stimulation (at the metallic contact), were studied at time intervals varying from one week to two years postimplantation. Long-term results, which only show dense fibrous encapsulation of the cables and the receiver, substantiate clinical belief regarding the "histological safety" of this electronic modality.