Pulse‐Generator Rejection of Probable Allergic Origin in Deep Brain Stimulation: A Rare Complication Successfully Managed with a Polytetrafluoroethylene‐Covered Device

Deep brain stimulation (DBS) is an effective treatment for movement disorders, however, it is not without hardware‐related complications. Among these, pulse‐generator (PG) allergy is extremely rare and poses a diagnostic challenge, since it can mimic other more common skin complications ¹ , ² , ³ , ⁴ , ⁵ , ⁶ , ⁷ and skin patch tests can be inconclusive. Here, we report a case of severe DBS PG rejection in a patient with Parkinson's disease (PD) managed by reimplanting a PG with an expanded polytetrafluoroethylene (ePTFE) covering.

Case Report

A 59‐year‐old man, diagnosed with PD in 2010, underwent bilateral subthalamic DBS surgery in September 2022, with the PG (Activa PC; Medtronic, Minnesota, USA) implanted in the left pectoral subcutaneous area. The procedure was uneventful, however, 4 months later, he developed swelling and skin erosion involving the pectoral pouch with PG exteriorization. A wound surgical cleaning with PG removal was performed and a new device of the same model was placed in a left abdominal pouch. Although the microbiological study was negative, the patient underwent a course of empirical antibiotic treatment. The complication seemed resolved, but recurred in August 2023 with abdominal wound swelling and erythema (Fig. 1A).

FIG. 1.

(A) An ill‐defined erythematous plaque with a reticular appearance was identified in the skin overlying the pulse‐generator. Progressively, herniation and spontaneous externalization of the device was observed in parallel with the erythematous inflammation of the skin. (B) Intraoperative image showing the sequence of the pulse‐generator covering with an expanded polytetrafluoroethylene membrane before its implantation into the pectoral pouch.

The patient was then evaluated by the dermatology department. Infection was ruled out and a skin biopsy was performed. Based on the clinical and histopathological characteristics, telangiectatic reticular erythema versus hypersensitivity reaction was suspected. Standard patch test series by the Spanish Contact Dermatitis Research Group were positive for potassium dichromate and for beryllium chloride. According to information provided by the PG manufacturer, the device was composed of stainless steel, titanium, silicone, polyetherimide, parylene, and polyurethane, therefore, our patch test results were considered to be of unknown relevance. Topical therapy with corticosteroids and calcineurin inhibitors was started and led to a temporary improvement. The lesions, however, significantly worsened in November 2023, so the abdominal PG was explanted leaving the two extension leads coiled in the previous pectoral subcutaneous pouch. New microbiological studies were negative. The wound finally healed completely without further treatment; however, the patient required treatment with an apomorphine subcutaneous pump because of a drastic worsening of his parkinsonian symptoms.

A decision was made to reimplant a new device covered with an ePTFE patch according to the experience of a few published cases of cardiac pacemaker allergy. A latest generation rechargeable PG model (Percept RC; Medtronic) was chosen for its smaller size and greater durability, with the same composition as the previous PG, according to the manufacturer (available at www.medtronic.com). Reimplantation was performed in the previous pectoral pouch, and the patch (Gore Preclude*) was watertight sutured around the case using 4/0 silk (Fig. 1B). During the subsequent 12 months of follow‐up, no further complications have arisen. DBS works well with monopolar configuration, and the patient is able to cope with his occupational and social activities, including riding his motorcycle (Video 1).

VIDEO 1.

The video demonstrates a neurological examination of the patient following the implantation of the expanded polytetrafluoroethylene‐covered device. A significant control of parkinsonian symptoms, specifically bradykinesia, is evident.

Discussion

Allergic reactions to DBS PG are extremely rare, and their incidence is still unknown. ⁵ In similar devices, as spinal neurostimulators and cardiac pacemakers, allergic events were, respectively, reported in 0.1% and 0.2% of patients, the most common allergens being polyurethane, silicon, titanium, nickel, and platinum. ⁵ , ⁶ , ⁸ , ⁹

Allergy to metal implants may pose a diagnostic challenge since detailed information regarding their precise composition is often unavailable, therefore, relevance of positive patch test results is difficult to determine. False‐negative results, particularly for titanium, are possible, with high rates of negative patch tests as reported in pacemakers allergies. ⁶ Robledo‐Nolasco et al ⁶ recommended diagnostic criteria for pacemaker allergies, such as exteriorization of the device within the first 6 months post‐implantation, repeated implant rejections, negative microbiological cultures, and no recurrence after implantation of a generator covered with gold or ePTFE. Our case met these criteria, therefore, an allergic reaction was suspected.

One case of DBS PG allergy has been published that was resolved by reimplanting a custom‐made silicone‐covered case. ⁴ In that report, the authors describe a fairly similar clinical sequence as in our patient: initial skin erosion over the PG, removal and reimplantation in the abdomen, new implant rejection, inconclusive patch tests, and definitive solution with a covered device.

There are currently no guidelines for the management of allergy to DBS implants. In pacemaker allergies, batteries coated with gold (not available for DBS implants), as well as silicone or ePTFE‐covered have been used. ⁶ , ⁸ To our knowledge, this is the first published case of DBS PG allergy successfully managed with an ePTFE‐covered device. Based on our experience, this approach is safe, more cost‐effective than other alternatives and, most importantly, does not interfere with Percept RC PG performance, allowing wireless adjustments and monopolar configuration if necessary. We recommend using a rechargeable PG to reduce the number of replacements in the long term. PG‐allergy could be more frequent than expected in DBS‐patients. Early diagnosis and treatment, once infection has been ruled out, are essential to achieve a satisfactory outcome.

Author Roles

(1) Research project: A. Conception, B. Organization, C. Execution; (2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique, C. Visualization and Preparation of Final Version.

J.A.: 1A, 1B, 1C, 3A, 3C

B.B.: 1C, 3B

P.J.G.: 1A, 1B, 3B

M.A.P.: 1B, 1C, 3B

J.S.: 1B, 3B

J.C.: 1A, 1C, 3B, 3C

Disclosures

Ethical Compliance Statement: We confirm that institutional review board or ethics committee approval was not required for this case report. All procedures performed were in accordance with the ethical standards of our institution, and with the 1964 Helsinki Declaration and its later amendments. The patient signed the corresponding informed consent for the publication of this case report and all iconographic and video materials. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Funding Sources and Conflicts of Interest: All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest in the subject matter or materials discussed in this manuscript. No specific funding was received for this work.

Funding Disclosures for the Previous 12 Months: The authors declare that there are no additional disclosures to report.

Data Availability Statement

Data sharing not applicable to this article as no datasets were generated or analysed during the current study.