====== Deep brain stimulation infections ======

[[Infection]] related to the [[deep brain stimulation]] (DBS) [[hardware]] causes significant [[morbidity]]: hardware explantation may be required; initial disease symptoms such as [[tremor]], [[rigidity]], and [[bradykinesia]] may recur; and the [[medication]] requirements for adequate disease management may increase. These morbidities are of particular concern given that published DBS-related infection rates have been as high as 23%. However, the key [[risk factor]]s for and the potential preventive measures against these infections remain largely uncharacterized. 
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Primalani et al. performed a retrospective review to evaluate the effectiveness of an antibiotic envelope to reduce SSI in DBS surgeries. This study included all DBS surgeries performed between August 2020 to May 2022 using a single-use, multifilament, antibiotic-coated mesh envelope wrapped around the DBS implantable pulse generator (IPG)(TYRX™ Absorbable Antibacterial Envelope, Medtronic Fridley, MN, USA). Standardized infection-prevention measures were applied and various patient-specific and surgery-specific factors were analyzed.44 patients were analyzed with 26 (59.1 %) primary implantations and 18 (40.9 %) revision surgeries. The median age was 65 years old with an average follow-up of 13.5 months (range of 3-24 months). The mean Body Mass Index was 24.0 (range 16.7-35.6). 8 (18.2 %) patients had underlying diabetes mellitus. There were only 2 (4.5 %) SSIs reported with neither involving the subcutaneous IPG and antibiotic envelope. 1 superficial-incisional SSI (2.3 %) was from a prior retro-auricular abscess around a lead wire requiring antibiotics and subcutaneous implant transposition. The other was a deep-incisional SSI (2.3 %) from repetitive trauma causing delayed scalp wound dehiscence and lead-wire extrusion, requiring antibiotics and wound revision. Both subjects were discharged well with no implants removed. The antibiotic envelope, therefore, appears to be a safe and well-tolerated adjunct that may reduce SSIs in DBS surgery. Further prospective work with larger sample sizes in a multi-institution setting is required
((Primalani N, Lan LC, Ang SYL, Ng WH, Rui WK. An antibiotic envelope to reduce infections in deep brain stimulation surgery. J Clin Neurosci. 2023 Jan;107:162-166. doi: 10.1016/j.jocn.2022.10.031. Epub 2022 Nov 19. PMID: 36414528.)).
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Feldmann et al. from the [[Charité]]-[[Berlin]], retrospectively analyzed [[incidence]] and [[infection]] characteristics in [[adult patient]]s who underwent two-staged [[DBS]] surgery with temporary externalization of [[lead]]s between January 2008 and November 2019. They focused on whether patients had participated in local field potential (LFP) recordings, and evaluated incidence of [[infection]]s at 3 months and 1 year after the surgery based on medical records. Infection rates were compared to major DBS studies and reports focusing on the risk of infection due to externalization of DBS leads. Results were visualized using descriptive statistics.

Between January 2008 and November 2019, DBS surgery was performed in 528 patients (389/139 patients in the LFP/non-LFP group), mainly for movement disorders such as Parkinson's disease (308), dystonia (93), and essential tremor (86). Of the patients, 72.9% participated in LFP recordings. The incidence of infections in the acute postsurgical phase (3 months) was 2.46% and did not differ significantly between the LFP group (1.8%) and the non-LFP group (4.32%). The overall incidence after 1 year amounted to 3.6% (19 patients) with no difference between LFP/non-LFP groups. Incidence rates reported in the literature show a large variety (2.6-10%), and the incidence reported here is within the lower range of reported incidences.

This study demonstrates that DBS is a surgical procedure with a low risk of [[infection]] in a large patient cohort. Importantly, it shows that LFP recordings do not have a significant effect on the incidence of infections in patients with externalization. With a representative cohort of more than 380 patients participating in LFP-recordings, this underlines LFP as a safe method in research and supports further use of this method, for example, for the development of adaptive stimulation protocols
((Feldmann LK, Neumann WJ, Faust K, Schneider GH, Kühn AA. Risk of Infection after Deep Brain Stimulation Surgery with Externalization and Local-Field Potential Recordings: Twelve-Year Experience from a Single Institution. Stereotact Funct Neurosurg. 2021 May 10:1-9. doi: 10.1159/000516150. Epub ahead of print. PMID: 33971662.)).
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In a retrospective review of 203 patients who underwent implantation of a DBS at Riverside University Health System Medical Center, [[Moreno Valley]], . For initial electrode placement, patients underwent either unilateral or bilateral electrode placement with implantation of the IPG at the same surgery and IPG replacements occurred as necessary. For patients with unilateral electrodes, repeat surgery for placement of contralateral electrode was performed when desired. Preoperative preparation with ethyl alcohol occurred in all patients while use of intra-operative vancomycin powder was surgeon dependent. All patients received 24 hours of postoperative antibiotics. Primary endpoint was surgical wound infection or brain abscess located near the surgically implanted DBS leads. Infections were classified as early (<90 days) or late (>90 days). Infectious organisms were recorded based on intra-operative wound cultures. Number of lead implantations, IPG replacements and choice of presurgical, intra-operative, and postsurgical antibiotics were recorded and outcomes compared.

Two hundred and three patients underwent 391 electrode insertions and 244 IPG replacements. Fourteen patients developed an infection (10 early versus 4 late); 12 after implantation surgery (3%) and 2 after IPG replacement surgery (0.8%). No intracranial abscesses were found. Most common sites were the chest and connector. Staphylococcus aureus (MSSA) was the most common organism. Intra-operative vancomycin powder did not decrease infection risk. Vancomycin powder use was shown to increase risk of infection after electrode implantation surgery (Relative Risk 5.5080, p = 0.02063). Complete hardware removal occurred in eight patients, one patient had electrode only removal, three patients with I&D and no removal of hardware, and two patients with removal of IPG and extensor cables only. All patients were treated with postoperative intravenous antibiotics and no recurrent infections were found in patients with hardware left in place.

Infections after DBS implantation and IPG replacement occurred in 3% and 0.8% of patients respectively in the study which is lower than reported historically. Early infections were more common. No intracranial infections were found. Intra-operative use of vancomycin was not shown to decrease risk of infection after electrode implantation surgery or IPG replacement. However, in our study it was shown to increase risk of infection after electrode implantation surgery. Treatment includes antibiotic therapy and debridement with or without removal of hardware. DBS hardware can be safely left in place in select patients who may have significant adverse effects if it is removed
((Bernstein JE, Kashyap S, Ray K, Ananda A. Infections in Deep Brain Stimulator Surgery. Cureus. 2019 Aug 20;11(8):e5440. doi: 10.7759/cureus.5440. PMID: 31632885; PMCID: PMC6797017.))
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Abode-Iyamah et al. from [[Iowa City]], endeavored to identify possible risk factors for DBS-related infection and analyze the efficacy of prophylactic intrawound [[vancomycin powder]] (VP).

They performed a retrospective [[cohort study]] of patients who had undergone primary DBS implantation at a single institution in the period from December 2005 through September 2015 to identify possible risk factors for [[surgical site infection]] (SSI) and to assess the impact of perioperative (before, during, and after surgery) prophylactic [[antibiotic]]s on the SSI rate. They also evaluated the effect of a change in the National Healthcare Safety Network's definition of SSI on the number of infections detected. Statistical analyses were performed using the 2-sample t-test, the Wilcoxon rank-sum test, the chi-square test, Fisher's exact test, or logistic regression, as appropriate for the variables examined

Four hundred sixty-four electrodes were placed in 242 adults during 245 primary procedures over approximately 10.5 years; most patients underwent bilateral electrode implantation. Among the 245 procedures, 9 SSIs (3.7%) occurred within 90 days and 16 (6.5%) occurred within 1 year of DBS placement. Gram-positive bacteria were the most common etiological agents. Most patient- and procedure-related characteristics did not differ between those who had acquired an SSI and those who had not. The rate of SSIs among patients who had received intrawound VP was only 3.3% compared with 9.7% among those who had not received topical VP (OR 0.32, 95% CI 0.10-1.02, p = 0.04). After controlling for patient sex, the association between VP and decreased SSI risk did not reach the predetermined level of significance (adjusted OR 0.32, 95% CI 0.10-1.03, p = 0.06). The SSI rates were similar after staged and unstaged implantations

While most patient-related and procedure-related factors assessed in this study were not associated with the risk for an SSI, the data did suggest that intrawound VP may help to reduce the SSI risk after DBS implantation. Furthermore, given the implications of SSI after DBS surgery and the frequency of infections occurring more than 90 days after implantation, continued follow-up for at least 1 year after such a procedure is prudent to establish the true burden of these infections and to properly treat them when they do occur
((Abode-Iyamah KO, Chiang HY, Woodroffe RW, Park B, Jareczek FJ, Nagahama Y, Winslow N, Herwaldt LA, Greenlee JDW. Deep brain stimulation hardware-related infections: 10-year experience at a single institution. J Neurosurg. 2018 Mar 1:1-10. doi: 10.3171/2017.9.JNS1780. Epub ahead of print. PMID: 29521584; PMCID: PMC6858932.))

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Four hundred twenty patients received 759 new DBS electrodes and 615 new internal pulse generators for the treatment of movement disorders or pain. Nineteen patients (4.5%) had an early (<6 mo) hardware-related infection requiring further surgery. There were no intracranial infections. Four patients presented with extensive cellulitis or wound dehiscence and were treated with total hardware removal. Fourteen patients presented with more localized infections and were treated by removal of the involved components only, followed by intravenously administered antibiotics. In nine of these patients, partial hardware removal successfully resolved the infection without requiring removal of the DBS electrodes. Wound washout alone was attempted in one patient and failed.

Conclusion: In a large series of new DBS hardware implantations, the incidence of postoperative hardware-related infection requiring further surgery was 4.5%. When only one device component was involved, partial hardware removal was often successful
((Sillay KA, Larson PS, Starr PA. Deep brain stimulator hardware-related infections: incidence and management in a large series. Neurosurgery. 2008 Feb;62(2):360-6; discussion 366-7. doi: 10.1227/01.neu.0000316002.03765.33. PMID: 18382313.)).
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