Editing Deep brain stimulation (section)

== Adverse effects ==
[[Image:Parkinson surgery.jpg|thumb|260px|The brain can shift slightly during [[stereotactic surgery]], leading to complications.]]
The possible negative effects of DBS can be divided into two categories: short-term in the immediate post operative period, and long-term on the scale of months to years.

Hardware related compliations include [[intracranial hemorrhage|bleeding inside the head]] (1–2%), infection (5%)  skin erosion (0.5%), lead migration (1.5%), lead fracture (1.5%), IPG malfunction (1%), which may require repositioning or a stay in the neurological [[intensive care unit]]. Long term negative effects of the device include an increased risk of decreased mental function and [[dementia]] beyond that typically seen with chronic neurologic disorders.<ref>{{cite journal | vauthors = Doshi PK | title = Long-term surgical and hardware-related complications of deep brain stimulation | journal = Stereotactic and Functional Neurosurgery | volume = 89 | issue = 2 | pages = 89–95 | date = April 2011 | pmid = 21293168 | doi = 10.1159/000323372 | s2cid = 10553177 }}</ref> Tourette's syndrome and epilepsy are more at risk of hardware related complications, with Parkinson's having the lowest rates, possibly due to abnormal mechanical positioning and picking behaviors associated with the former two conditions.<ref name = "Complications 2017"/> Delayed brain edema can occur after lead placement, but is usually self limited.<ref>{{cite journal |last1=de Cuba |first1=CM |title=Idiopathic delayed-onset edema surrounding deep brain stimulation leads: Insights from a case series and systematic literature review. |journal=Parkinsonism & Related Disorders |date=November 2016 |volume=32 |pages=108–115 |doi=10.1016/j.parkreldis.2016.09.007 |pmid=27622967|hdl=11577/3313586 |hdl-access=free }}</ref>

Because the brain can shift slightly during surgery, the electrodes can become displaced or dislodged, though electrode misplacement can be suspected by lack of clinical effect when the leads are turned on and a sudden dramatic increase in electrode [[Electrical impedance|impedance]]. The displacement can be physically located using [[CT scan]], which would then guide a repeat intervention for repositioning. After surgery, swelling of the brain tissue, mild disorientation, and sleepiness are normal. After 2–4 weeks, the [[Surgical suture|sutures]] are removed and the neurostimulator is activated.<ref>{{cite journal |last1=Deuschl |first1=G |last2=Herzog |first2=J |last3=Kleiner-Fisman |first3=G |title=Deep brain stimulation: postoperative issues. |journal=Movement Disorders |date=June 2006 |volume=21 Suppl 14 |pages=S219-37 |doi=10.1002/mds.20957 |pmid=16810719}}</ref>

Expectations can impact surgical outcomes, with individuals that had more positive expectations generally having better motor outcomes. Bradykinesia was in particular responsible to verbal suggestions. The placebo response rate in the Parkinson's population similar to other neurologic diseases at 16% (range 0-55%). Conversely, those that had unrealistic expectations surrounding surgery because they anticipated improvement and symptoms that are not typically addressed by neurostimulation, reported being unhappy about the outcome as well. With regards to particular symptoms, expectations of improvements in motor symptoms and medication reduction were mostly met, whereas expectations regarding non-motor issues such as speech, balance, and walking problems were not.<ref>{{cite journal |last1=Mameli |first1=F |last2=Zirone |first2=E |last3=Girlando |first3=R |last4=Scagliotti |first4=E |last5=Rigamonti |first5=G |last6=Aiello |first6=EN |last7=Poletti |first7=B |last8=Ferrucci |first8=R |last9=Ticozzi |first9=N |last10=Silani |first10=V |last11=Locatelli |first11=M |last12=Barbieri |first12=S |last13=Ruggiero |first13=F |title=Role of expectations in clinical outcomes after deep brain stimulation in patients with Parkinson's disease: a systematic review. |journal=Journal of Neurology |date=November 2023 |volume=270 |issue=11 |pages=5274–5287 |doi=10.1007/s00415-023-11898-6 |pmid=37517038|pmc=10576668 }}</ref>

MRIs can be obtained after the procedure when necessary, but they have to be done under strict guidelines due to risks such as heating of the leads and to a lesser degree lead migration. The current FDA approved manufacturer (Medtronic) recommendations are interrogation of the system prior to the MRI; assessment of [[electrical impedance|impedance]] to rule out short or open [[Balanced circuit|circuits]] and compromise of system integrity; that the DBS be off, programmed at zero volts, bipolar mode with the magnetic switch disabled, only a 1.5-T MRI head transmit/receive coil with specific absorption rate of less than 0.1 W/kg in the head. Multiple centers have found these guidelines to be overly cautious.<ref>{{cite journal |last1=Bronstein |first1=JM |title=Deep brain stimulation for Parkinson disease: an expert consensus and review of key issues. |journal=Archives of Neurology |date=February 2011 |volume=68 |issue=2 |page=165 |doi=10.1001/archneurol.2010.260 |pmid=20937936|pmc=4523130 }}</ref>