Postsurgical Pathologies Associated with Intradural Electrical Stimulation in the Central Nervous System: Design Implications for a New Clinical Device

Abstract

Spinal cord stimulation has been utilized for decades in the treatment of numerous conditions such as failed back surgery and phantom limb syndromes, arachnoiditis, cancer pain, and others. The placement of the stimulating electrode array was originally subdural but, to minimize surgical complexity and reduce the risk of certain postsurgical complications, it became exclusively epidural eventually. Here we review the relevant clinical and experimental pathologic findings, including spinal cord compression, infection, hematoma formation, cerebrospinal fluid leakage, chronic fibrosis, and stimulation-induced neurotoxicity, associated with the early approaches to subdural electrical stimulation of the central nervous system, and the spinal cord in particular. These findings may help optimize the safety and efficacy of a new approach to subdural spinal cord stimulation now under development.

Chronic tissue response to untethered microelectrode implants in the rat brain and spinal cord

“…However, immunohistological data from spinal cord [32] electrode implants is very rare. In most studies, epidural [33], or subdural [34, 35] stimulation approaches are taken in human subjects due to the high risk of neural trauma that may result from the mechanical stress induced by any rigid body implanted into the spinal cord.…”

Intrathecal Therapeutics: Device Design, Access Methods, and Complication Mitigation

“…We anticipate that the same considerations will hold for leads delivered directly into the intrathecal space. While intradural electrode arrays saw significant clinical use at the origin of spinal cord stimulation in the 1960s and 1970s , placement was by surgical open durotomy and it is only recently that research has begun into new forms of the intradural approach . It is very likely that extension of the existing percutaneous methods for accessing the intrathecal space will eventually be used for placement of specially designed stimulator leads, in much the same way that recording leads have long been inserted there to monitor spinal cord evoked potentials .…”

In Vivo Measurements of the Frequency-Dependent Impedance of the Spinal Cord

“…�ere is at present no spinal cord equivalent of a direct brain stimulation (DBS) system, in that virtually all of the SCS devices now in clinical use are implanted in the epidural space and thus encounter fundamental performance limits dictated by the presence of the intervening layer of CSF. �e approach that we have proposed and are investigating [57] seeks to circumvent this limitation through direct intradural stimulation, and to re-introduce that method [58] as a clinical option employed against intractable neuropathic pain and the spasticity arising from spinal cord injury [59]. �is would represent a significant departure from the status quo, wherein intradural placement of a stimulator lead is either an inadvertent result of attempted epidural placement [60] or, rarely, an intentional means of having the body of the lead serve as a dural substitute [61].…”