Fatigue fracture of a DBS extension cable: a pictorial review

Non-deep brain stimulation (DBS) lead hardware complications are quite uncommon. They are observed more with tremor and dystonia patients due to constant strain on the neck region. However, occurrence of such complication over a two-decade period has not been reported. Twenty years after DBS implantation, a patient presented with a wear and tear fracture in the extension cable, which we describe as a fatigue fracture of the extension cable. Delayed hardware complications following DBS implantation is an under-reported entity due to follow-up compliance over the long term. Reporting such complications is essential to understand the durability of the hardware, and to anticipate and manage implant failure.

Managing Lead Fractures in Deep Brain Stimulation for Movement Disorders: A Decade-Long Case Series from a National Neurosurgical Centre

Background: Deep brain stimulation (DBS) is an effective treatment for movement disorders, but its long-term efficacy may be undermined by hardware complications such as lead fractures. These complications increase healthcare costs and necessitate surgical revisions. The frequency, timing, and clinical factors associated with lead fractures remain poorly understood. Objective: This study aimed to determine the incidence, timing, and clinical factors associated with lead fractures in a large cohort of DBS patients over a 10-year period. Methods: This retrospective study analyzed data from 325 patients who underwent bilateral DBS implantation at the National Centre for Neurosurgery from 2013 to 2023. The analysis specifically focused on 17 patients who experienced lead fractures during the long-term follow-up period. Results: Among the 325 patients, lead fractures were identified in 17 patients (5.23%), affecting 18 electrodes. The majority of cases involved patients with Parkinson's disease (76.5%) or dystonia (23.5%), with an average age of 59.17 ± 8.77 years. Nearly all patients with lead fractures had a history of trauma. Additionally, two cases were associated with active engagement in sports, particularly activities involving movements like pulling up on a horizontal bar, while Twiddler's Syndrome was identified in two other cases. All electrode fractures required surgical revision. Conclusions: Lead fractures, while rare, remain a significant complication in DBS systems. Precise surgical techniques, early detection, and advancements in DBS hardware design may help to mitigate this risk. Future innovations, such as durable leads or wireless systems, may improve long-term outcomes in DBS therapy for movement disorders.

Preliminary Experience with a Four-Lead Implantable Pulse Generator for Deep Brain Stimulation

BACKGROUND

Implantable pulse generators (IPGs) store energy and deliver electrical impulses for deep brain stimulation (DBS) to treat neurological and psychiatric disorders. IPGs have evolved over time to meet the demands of expanding clinical indications and more nuanced therapeutic approaches.

OBJECTIVES

The aim of this study was to examine the workflow of the first 4-lead IPG for DBS in patients with complex disease.

METHOD

The engineering capabilities, clinical use cases, and surgical technique are described in a cohort of 12 patients with epilepsy, essential tremor, Parkinson's disease, mixed tremor, and Tourette's syndrome with comorbid obsessive-compulsive disorder between July 2021 and July 2022.

RESULTS

This system is a rechargeable 32-channel, 4-port system with independent current control that can be connected to 8 contact linear or directionally segmented leads. The system is ideal for patients with mixed disease or those with multiple severe symptoms amenable to >2 lead implantations. A multidisciplinary team including neurologists, radiologists, and neurosurgeons is necessary to safely plan the procedure. There were no serious intraoperative or postoperative adverse events. One patient required revision surgery for bowstringing.

CONCLUSIONS

This new 4-lead IPG represents an important new tool for DBS surgery with the ability to expand lead implantation paradigms for patients with complex disease.

The Safety of Micro-Implants for the Brain

Technological advancements in electronics and micromachining now allow the development of discrete wireless brain implantable micro-devices. Applications of such devices include stimulation or sensing and could enable direct placement near regions of interest within the brain without the need for electrode leads or separate battery compartments that are at increased risk of breakage and infection. Clinical use of leadless brain implants is accompanied by novel risks, such as migration of the implant. Additionally, the encapsulation material of the implants plays an important role in mitigating unwanted tissue reactions. These risks have the potential to cause harm or reduce the service of life of the implant. In the present study, we have assessed post-implantation tissue reaction and migration of borosilicate glass-encapsulated micro-implants within the cortex of the brain. Twenty borosilicate glass-encapsulated devices (2 × 3.5 × 20 mm) were implanted into the parenchyma of 10 sheep for 6 months. Radiographs were taken directly post-surgery and at 3 and 6 months. Subsequently, sheep were euthanized, and GFAP and IBA-1 histological analysis was performed. The migration of the implants was tracked by reference to two stainless steel screws placed in the skull. We found no significant difference in fluoroscopy intensity of GFAP and a small difference in IBA-1 between implanted tissue and control. There was no glial scar formation found at the site of the implant’s track wall. Furthermore, we observed movement of up to 4.6 mm in a subset of implants in the first 3 months of implantation and no movement in any implant during the 3–6-month period of implantation. Subsequent histological analysis revealed no evidence of a migration track or tissue damage. We conclude that the implantation of this discrete micro-implant within the brain does not present additional risk due to migration.

Experience to prevent wire tethering in deep brain stimulation from a single center

OBJECTIVE

To analyze the causes of wire tethering in deep brain stimulation (DBS) and propose ways to prevent it.

METHODS

A total of 70 consecutive patients (140 electrodes) operated for DBS in our department from September 2017 to December 2019 were analyzed to document wire tethering, respectively, in the initial period (September 2017-June 2018) and the late period (July 2018-December 2019). The patients come back to our clinic 1 month postoperatively to turn on the equipment and followed up any time postoperatively face to face.

RESULTS

Wire tethering was divided into mild, moderate and severe. The frequency of mild wire tethering was 12.5% (2/16) in the initial period and 9.3% (5/54) in the late period. The frequency of moderate wire tethering was 12.5% (2/16) in the initial period and 3.7% (2/54) in the late period. There was only one patient suffered from severe wire tethering in the initial period and none in the late period. There was a significant difference between the initial (31.3%) and the late (13%) periods in the frequency of total wire tethering.

CONCLUSIONS

Wire tethering is a rare but serious hardware complication in DBS which should be noteworthy. Improving surgical skill when implanted the extension wire and inventing new material covering extension wire can prevent wire tethering.

Motor Cortex Stimulation Reversed Hypernociception, Increased Serotonin in Raphe Neurons, and Caused Inhibition of Spinal Astrocytes in a Parkinson's Disease Rat Model

Persistent pain is a prevalent symptom of Parkinson’s disease (PD), which is related to the loss of monoamines and neuroinflammation. Motor cortex stimulation (MCS) inhibits persistent pain by activating the descending analgesic pathways; however, its effectiveness in the control of PD-induced pain remains unclear. Here, we evaluated the analgesic efficacy of MCS together with serotonergic and spinal glial modulation in an experimental PD (ePD) rat model. Wistar rats with unilateral striatal 6-OHDA and MCS were assessed for behavioral immobility and nociceptive responses. The immunoreactivity of dopamine in the substantia nigra and serotonin in the nucleus raphe magnus (NRM) and the neuronal, astrocytic, and microglial activation in the dorsal horn of the spinal cord were evaluated. MCS, without interfering with dopamine loss, reversed ePD-induced immobility and hypernociception. This response was accompanied by an exacerbated increase in serotonin in the NRM and a decrease in neuronal and astrocytic hyperactivation in the spinal cord, without inhibiting ePD-induced microglial hypertrophy and hyperplasia. Taken together, MCS induces analgesia in the ePD model, while restores the descending serotonergic pathway with consequent inhibition of spinal neurons and astrocytes, showing the role of MCS in PD-induced pain control.