Most of us with DBS don't want to consider the possibility of acquiring a DBS-related infection. On the one hand, we want to learn all the details as we assume that knowledge is power. On the other hand, sometimes we only want to know the bare minimum, realizing that knowledge can cause undue anxiety.
Thankfully, I haven’t experienced a DBS-related infection, but I have met a number of patients who have. It’s not fun, but fortunately it's usually not deadly. The following is what you need to know (or perhaps more than you need to know) about DBS infections.
Infectious Disease Specialist’s Perspective: What You Need to Know About Deep Brain Stimulation Infections
by Ryan Oyer, MD
This information is from the presentation made by Ryan Oyer, MD, Fellow, Division of Infectious Diseases, University of Colorado, Presentation to the Bionic Brigade (Denver’s DBS Support Group) on March 9, 2012.
When do bacterial infections occur?
Bacterial infection occurs when pathogenic bacteria gain access to otherwise sterile body compartments and multiply.
What are the post surgical infection rates?
Although post surgical infections are common, there is not one central organization that maintains a database of infection rates. The “best guess” rates are as follows
• Deep brain stimulators (DBS)~5%
• Published range 0-22%
You indicated that human skin is colonized by billions of bacteria. What skin colonizers are the most common cause of post-surgical infection?
• Staphylococcus aureus (MSSA, MRSA)
• Staphylococcus epidermidis (MSSE, MRSE, coagulase neg staph (CoNS))
• Propionibacterium acnes (P.acnes)
What factors influence the incidence of DBS infection?
• Host factors (comorbidities such as diabetes, malnutrition, anemia): increase the risk of infection.
• The length of surgery: The longer the surgery, the more likely the chance of infection.
• Use of prophylactic antibiotic administration: decreases the risk of infection.
• Type of skin preparation of Iodine vs. Chlorhexadine: Chlorhexadine decreases infection.
• Razor vs. clippers: The use of clippers decreases rates of infection relative to razors.
• Handling hardware: the more that it’s handled, the higher the risk of infection.
• Staged procedures with externalization of hardware: increase the risk of infection.
• Topical antibiotics to wound at closure: One study has shown a decrease in infection with the use of a topical antibiotic.
• Curved vs. straight incision: Curved incision decreases rates of infection relative to straight incision.
• Placement of hardware in relation to incision: Hardware under a flap with a curved incision vs. directly under the incision has a lower infection rate.
How is DBS hardware infection diagnosed?
The clinical signs and symptoms are:
• Warmth (calor)
• Pain (dolor)
• Redness (rubor)
• Swelling (tumor)
• Headache, fever, altered mental status (especially brain abscesses)
• Malaise, poor appetite, night sweats
• Poor wound healing, prolonged wound discharge
• Wound “dehiscence” (separation)
• Erosion of any hardware through skin
• Cellulites (skin inflammation caused by infection)
How are DBS infections treated?
DBS infections are treated by surgery and IV antibiotics.
• Most often, surgery to explant (remove) some or all of the hardware will be recommended.
• If the infection is thought to involve only soft tissue and not hardware, an oral/IV antibiotic course may be entertained without surgery.
• Many physicians will try to salvage the intracranial electrodes by treating with a course of IV antibiotics prior to explantation, especially if infection is located at IPG or extension.
• If intracranial infection is seen on imaging (or suspected), the intracranial electrodes must be explanted.
Does bacterial species influence treatment decisions?
• Yes, mainly it influences antibiotic choice and sometimes affects surgery.
• Staph species are the most common cause of DBS infection. Staph aureus- aggressive bacteria is nearly impossible to get off hardware, requiring surgery.
MSSA- methicillin sensitive staphylococcus aureus
MRSA- methicillin resistant staphylococcus aureus. These bacteria are of the same species, but MRSA has additional genes which make it resistant to some antibiotics.
Coagulase negative staph (coag negative staph) is a less aggressive cousin of S.aureus, sometimes can sterilize hardware without surgery.
CoNS or Staph epidermidis
Why is staph infection so difficult to treat?
• Staph is sticky. It has proteins/sugars on its surface that bind firmly to tissues and hardware.
• Staph (and others) produce “biofilm” which makes delivering adequate concentrations of antibiotics to the cell surface very difficult.
• Dental plaque (tartar) is a biofilm.
How are long-term IV antibiotics administered?
• There are no “official” guidelines to follow.
• The literature suggests IV antibiotics should be given for 2-6 weeks.
• You do not need to be in the hospital.
• PICC lines (Peripherally Inserted Central Catheters) are generally used for long-term IV antibiotics.
• Home health nurses provide PICC line teaching so daily antibiotic infusions can be given at home.
• Blood tests are checked weekly and reviewed by ID specialists whom should be seen every 2 weeks.
What are the possible complications from PICC lines?
• Blood clot (deep venous thrombosis)
How is it decided what antibiotic to use?
• Ideally bacterial cultures taken from the area of infection in the operating room (tissue/hardware/fluid) will grow bacteria to guide this decision.
• Antibiotic choice is determined from the susceptibility profile of these cultures.
• Generally can narrow to one antibiotic.
• Consideration is made for ease of dosing.
• If cultures are negative, the presumed infection is treated “empirically.”
• For broad spectrum infections, multiple antibiotics are often used.
Which antibiotics are used most often?
Anti-staph agents: Nafcillin, Ceftriaxone, Vancomycin, Daptomycin
Broad spectrum agents: Ertapenem, Zosyn, Cefepime
What you can do to decrease your risk of infection?
Unfortunately, there is not much a patient can do except for the following:
• Good local wound care
• Avoid wound immersion
• Chlorhexadine topical cleaning at home prior to operation
• Choose an experienced neurosurgeon/medical center
Once your infection is treated, when can you get a new DBS?
• Most physicians recommend waiting at least 8-12 weeks after the completion of antibiotic course.
• If hardware is left in place, they recommend the same.
• There is some increased risk of continued infection.