A Fully Implantable Miniaturized Liquid Crystal Polymer (LCP)-Based Spinal Cord Stimulator for Pain Control

Spinal cord stimulation is a therapy to treat the severe neuropathic pain by suppressing the pain signal via electrical stimulation of the spinal cord. The conventional metal packaged and battery-operated implantable pulse generator (IPG) produces electrical pulses to stimulate the spinal cord. Despite its stable operation after implantation, the implantation site is limited due to its bulky size and heavy weight. Wireless communications including wireless power charging is also restricted, which is mainly attributed to the electromagnetic shielding of the metal package. To overcome these limitations, here, we developed a fully implantable miniaturized spinal cord stimulator based on a biocompatible liquid crystal polymer (LCP). The fabrication of electrode arrays in the LCP substrate and monolithically encapsulating the circuitries using LCP packaging reduces the weight (0.4 g) and the size (the width, length, and thickness are 25.3, 9.3, and 1.9 mm, respectively). An inductive link was utilized to wirelessly transfer the power and the data to implanted circuitries to generate the stimulus pulse. Prior to implantation of the device, operation of the pulse generator was evaluated, and characteristics of stimulation electrode such as an electrochemical impedance spectroscopy (EIS) were measured. The LCP-based spinal cord stimulator was implanted into the spared nerve injury rat model. The degree of pain suppression upon spinal cord stimulation was assessed via the Von Frey test where the mechanical stimulation threshold was evaluated by monitoring the paw withdrawal responses. With no spinal cord stimulation, the mechanical stimulation threshold was observed as 1.47 ± 0.623 g, whereas the stimulation threshold was increased to 12.7 ± 4.00 g after spinal cord stimulation, confirming the efficacy of pain suppression via electrical stimulation of the spinal cord. This LCP-based spinal cord stimulator opens new avenues for the development of a miniaturized but still effective spinal cord stimulator.

Spinal Cord Stimulator for Treating Chemotherapy-induced Peripheral Neuropathy

BACKGROUND: Chemotherapy-induced peripheral neuropathy (CIPN) is not only one of the most common adverse experiences of cancer survivors, but it is also one which has the greatest effect on quality of life. Ultimately, CIPN can lead to unwanted modification of treatment such as chemotherapy dose reductions or termination of treatment altogether. CASE REPORT: We present a case of a 47-year-old man with severe bilateral CIPN resistant to conservative management, who was successfully treated with spinal cord stimulation. CONCLUSION: Spinal cord stimulation can be an effective treatment for CIPN resistant to conservative management. KEY WORDS: Spinal cord stimulator, chemotherapy induced neuropathy, peripheral neuropathy

Exposed Hardware: A True Contraindication for a Spinal Cord Stimulator? A Case Report and Review of the Literature

BACKGROUND: Infection is one of the most common complications of spinal cord stimulator (SCS) implantation and causes severe morbidity for the patients and is costly for the health system and insurance. Every effort to minimize the risk of infection Post-SCS implantation has to be made. CASE REPORT: A 55-year-old man suffered right arm brachial plexus avulsion and subdural hematoma requiring a craniotomy and subsequently a cranioplasty with a metal mesh in 1998. Over the years he developed significant neuropathic pain which was controlled with a combination medication regimen until recently. In our clinic, a trial of cervical SCS showed significant improvement of pain. The consulting neurosurgeon, while evaluating his skull, noticed a very small skin defect, exposing a metal plate with no signs of infection. Based on that, he refused to implant the SCS. The patient is now seeking alternative treatment methods. CONCLUSION: Well-designed animal/human studies investigating the effects of exposed hardware for seeding infection to remote implants in the body are required to scientifically extrapolate if exposed hardware is a true contraindication for implanting an SCS or other devices in the body. KEY WORDS: Spinal cord stimulator, brachial plexus injury, complex regional pain syndrome, exposed hardware, surgical infection