Skin erosion in deep brain stimulation procedures: Using the temporalis muscle to treat this complication - A technical note.

BACKGROUND: Skin erosion is a common complication after deep brain stimulator procedures. Despite being a relatively common event, there is no standard surgical technique or a widely accepted guideline for managing this kind of complication.
METHODS: We describe a case of cutaneous erosion in the connector's site of deep brain stimulation case, surgically managed with anterior displacement of the connectors and overlapping and wrapping the connections within the temporal muscle.
RESULTS: Postoperatively, the patient did well and achieved complete resolution of the skin erosion, with no signs of infection or new skin lesions.
CONCLUSION: This technique demonstrated to be effective in this case in the long-term follow-up. Copyright:

INTRODUCTION

Deep brain stimulation (DBS) has become increasingly common for patients with disabling symptoms due to movement disorders such as Parkinson’s disease, dystonia, and tremor.[5,9] Thus, the number of adverse events related to the surgical procedure has also increased.[7] Despite being an increasingly performed procedure, some adverse events are still not fully understood, once clinical trials are typically conducted for a short time, and serious adverse events are relatively infrequent.[24]

Skin erosion is the loss of epidermis over the implants (leads, internal pulse generator, wires, or extensions), exposing hardware and predisposing to local infections. Skin complications are the most common hardware-related complications, ranging from 1% to 15%.[11,21,23,28] Erosions occur most commonly at the connector site, particularly when it is located over the mastoid region.[14,16]

Therefore, the authors describe a case of cutaneous erosion in DBS implants that were managed using a technique not yet described in the literature.

CASE REPORT

We present the case of a 62-year-old female diagnosed with Parkinson’s disease with 10 years of the onset of the first symptoms. A 5 years of the initial diagnosis she developed on and off motor fluctuations, which responded initially to the optimized clinical treatment. About 2 years after, she was still experiencing frequent on and off periods associated with dyskinesias. This patient was assessed again by a movement disorders neurologist and was referred to the DBS surgical counseling. She underwent a full subthalamic nucleus DBS implant procedure in November 2018. In January 2019, during her recovery, she fell and sustained a minor head trauma, with abrasions on the lateral incision located close to the connector’s site without wound dehiscence. In March 2019, an erosion of the connectors site [Figure 1] without evident associated infection or discharge was promptly identified when patient came for normal follow-up (FU) appointment. The surgical treatment was promptly performed on the same day, with careful debridement and release of the electrodes, connectors, and extensions to mobilize them anteriorly below the temporalis muscle that was incised to allow creating a space underneath it. By producing this space, the DBS connectors were inserted here being involved and wrapped by the most anterior part of the temporal muscle [Figures 2 and 3] to minimize the risk of further erosions. Unabsorbable sutures with Nylon were used to keep the muscle over the implants. We felt at the time of the procedure that by trying to cover the implants with local soft tissue without using a skin flap would be a reasonable choice minimizing a more extensive procedure. 500 mg of vancomycin powder (VP) was used on the surgical site, followed by 4 weeks of oral antibiotics (ceftriaxone). Follow-up of this case was unremarkable, without evidence of new erosions or infection of the neurostimulation hardware until the submission of this manuscript. No microorganisms were identified following swabs collected from the intraoperative procedure.

Figure 1:

Skin erosion at the connector’s site.

Figure 2:

Exposure of the leads and connectors. Debridement and release of adhesions.

Figure 3:

Anteriorization of connectors and the extensions and placement underneath the splitted temporal muscle. Implants envolved and wrapped by the temporal muscle with topical vancomycin powder and secured with unabsorbable nylon sutures.

DISCUSSION

DBS is an effective and established treatment for movement disorders.[2,12,18-20,27] Any surgical procedure with implants carries a risk of complications derived from the foreign body inserted in the patients. DBS procedures introduced a new series of possible complications related to its hardware. Infection, malfunction, lead migration, or system fracture can increase patient morbidity and should be considered when assessing and also consenting patients with regard to risks/benefits of this therapy.[7,10,14] The use of DBS for less frequent indications or conditions, such as Tourette’s syndrome, cluster headache, and refractory partial epilepsy, was found to bear a higher incidence of hardware-related infections than the most usual and established indications such as Parkinson’s disease and other movement disorders.[16]

Several techniques were described in the literature for the management of scalp erosions related to brain stimulation implants. The most commonly used treatments are debridement and simple skin closure followed by antibiotics, as well as removal and/or replacement of parts of the system.[8,14] Simple skin closure after surgical debridement is often performed by many centers as an attempt to save the implants in patients that are having benefits provided by the therapy. Also trying to save and keep these costly implants can be an effective and potentially less expensive option. Some centers, on the other hand, precede with removal of parts of the system or in some cases all the hardware.

In a prospective analysis of 144 patients who underwent DBS, Constantoyannis et al. reported that straight incisions on the scalp increased the risk of infection compared with curvilinear incisions.[8] Zhou et al. also proposed a modified skin incision to reduce skin-related complications. The double C-shaped incision was compared with the traditional incision and was shown to successfully reduce the incidence of skin complications.[28]

In another study with 161 DBS patients, 24 had hardware-related complications. Only one patient had system infection, which occurred in the implanted battery (IPG). Skin erosion occurred in two patients (1.24%), one at the IPG site and one at the connector extension in the retromastoid region. For management of retromastoid erosion, the connector was moved medially to a new occipital bone groove. Skin erosion healed over time without removing the leads and extensions.[15] Staudt et al. presented five cases of scalp erosion at the burr hole site. The average age of the patients was 67 years (53–77 years) and none of them presented signs of systemic infection. Two patients underwent local debridement and primary closure because the scalp defect was <1 cm. However, both had erosion recurrence and were eventually treated with a rotational flap. The remaining three patients underwent debridement and rotational flap as initial treatment. Thus, these five patients underwent a vascularized, tension-free rotational scalp flap with preservation of the electrodes under the pericranium. All patients had healthy flaps, the DBS hardware was functional, and there was no evidence of infection or local pain.[26]

Another case was reported by Lanotte et al., in which one patient presented with a small scalp erosion (2 cm2) after a head trauma, and after excluding the presence of infection, surgical reconstruction was performed. With a portable Doppler, the frontal branch of the right temporal artery was located. The skin covering the device was completely excised and the flap was designed and harvested from the right half of the forehead to the innominate fascia. Another skin triangle was excised to allow flap rotation without tunneling. The donor area was grafted with the skin from the retroauricular region. Three months later, the flap was healthy and without signs of infection.[17]

To prevent hardware erosion, Barrett et al. used an acellular dermal matrix that was surgically placed under the skin of 20 patients who had imminent signs of erosion. None of the patients treated with this technique required new hardware revision or removal surgery.[4] Spiotta et al. presented two different approaches for managing hardware complications. The first technique was used in a 54-year-old patient who presented with erosion and infection at the burr hole site after a minor trauma. For this case, a temporoparietal occipital flap based on the superficial temporal artery with or without scalp expansion was used. In the second approach, in a 65-year-old patient, a scalp fasciocutaneous flap with or without cranioplasty was used, circumventing the prominence of the electrode to prevent future erosion. At the FU appointment 2 weeks later, the wounds were well healed.[25] In a series of 21 patients with skin erosion after placement of DBS, Gómez and Hontanilla also used flaps to cover the skin defect, originating from the scalp itself (rotation flap), latissimus, thigh, or forearm.[13] According to some authors, using VP on the wounds seems to be safe and reduce the incidence of surgical site infections after DBS procedures.[1,22] In one long retrospective study with 242 patients who undergone 245 DBS implantations, the authors showed that the surgical site infection in the group that received intrawound topical VP was 68% lower despite some limitations of this work.[1] Other authors have not shown that the use of VP is beneficial.[6] In our practice, we recommend the use of intrawound VP since it increases the antibiotic concentrations locally[3] without further risks, thus decreasing the incidence of infection.

CONCLUSION

There is no standardized technique for managing scalp erosions in the literature. All methods described for managing this type of complication are valid and have satisfactory results. Many high-volume DBS centers have their own experience and way of resolving hardware complications and especially skin erosions. Despite the lack of a unique or single surgical technique suitable for all cases of skin complications, the most important fact is that each case will probably have a more suitable and personalized treatment option. Surgical flaps demonstrated to be efficient resolving skin erosions and also skin retractions as well. For some cases creating grooves on the skull bone can also be performed to bury the connections. In this particular case report, we demonstrated that mobilizing the connectors anteriorly to be overlapped and wrapped by the temporal muscle was effective in this case without the use of a skin flap. Also using VP seems to be efficient and prevents infection.

Statement of ethics

The authors have no ethical conflicts to disclose. Written informed consent was obtained from the patient for publication of this case report and any accompanying images.