Immediate post-operative complications
- e.g. intra-cerebral haematoma, seizures etc.
- Clinical assessment +/- an emergent CT head.
- Stimulation is not typically turned on for several weeks post operatively so any deficits will not represent a stimulation side effect.
- Should the patient require a return to theatre then monopolar diathermy should not be used with DBS in situ.
- Chronic Parkinson’s patient’s can exhibit a dramatic difference in their on and off medication state so it is worth clarifying if they received a dose of L-dopa intra-operatively if they are noted to be akinetic post-op.
- Conversely, transient increases in dyskinesia are not infrequently seen following STN DBS.
Wound problems
- Erosion
- Removal of DBS hardware and interruption of stimulation is not itself without considerable potential morbidity.
- The most common area for problems to occur is over the implantable pulse generator (IPG)
- However, any part of the apparatus can be affected from intracranial electrodes to extension leads and IPG
- It is better to treat erosions early with a wound revision prior to the implant breaking through the skin as the latter almost certainly means the hardware will need to be removed with commensurate morbidity.
- Infection
- Wound infection
- S aureus is the most common infective pathogen
- Units that perform DBS should have an antibiotic protocol.
- Anything more significant than a localized superficial surgical site infection (SSI) has a high chance of requiring removal of at least some of the hardware.
- Typically, even presumed superficial infections are managed more aggressively than other SSIs in the hope of arresting infection spread.
- Superficial wound infection
- 7 days intravenous antibiotics + 2 further weeks of oral therapy.
- Following, antibiotic cessation the patient is then reviewed frequently and any clinical or biological evidence of relapse will normally be managed with surgical explanation of the affected part e.g. IPG and/or extension leads.
- Very occasionally an allergic reaction to metallic hardware masquerading as infection can be seen.
- Re-implantation following an infection
- Many centres will wait 6 months.
- It would be very unusual to re-implant any earlier than 3 months.
- Intracranial infections
- Including brain abscesses can occur, albeit rarely.
- Investigate
- Contrast enhanced CT scan
- MRI can also be obtained with modern DBS systems subject to certain conditions
- Typically this will be seen in the context of infection of the extracranial portion of the electrode combined with new neurological manifestations and imaging showing oedema around the electrodes.
- Differential diagnosis
- Include idiopathic delayed-onset edema (IDE; an area of oedema restricted to the peri-electrode region),
- A rare probable immune-mediated foreign body response which appears self-limiting and can often be managed conservatively with steroids perhaps expediting recovery
- Also rarely described are aseptic intraparencymal cysts, with a possible related immune or inflammatory aetiology.
- However, in both cases intracranial infection should be excluded in the first instance with clinical, biochemical and imaging evaluation.
Implant/hardware malfunction
- If over long time
- Loss of device efficacy
- Tolerance is described over time, and the underlying disease process e.g. Parkinson’s disease also continues to progress.
- It often takes the skillset of an experienced neurologist to distinguish disease symptoms from those attributable to stimulation.
- If acute
- Device malfunction and battery depletion
- A history of trauma or exposure to strong magnetic fields should be sought.
- Device interrogation
- Checking impedances
- Current drain at each of the DBS contacts with the appropriate programmer
- Lead fracture
- Clinical features
- Intermittent symptoms which occur during movements or in certain postures.
- Most common reported site of fracture is the cervical area, involving the extension wires.
- Investigation
- Device interrogation
- Impedance increased
- Impedance low
- ‘Short circuit’ of wires within the lead- in which case they will be abnormally low.
- Plain x-rays
- Might show breakages
- But not all the time
- CT head
- Can be fused with a previous MRI to exclude intra-cranial lead migration, which is unusual.
- ‘Twiddler’s Syndrome’
- Some patients are known to consciously or subconsciously manipulate their IPG in its pocket resulting in twisting and potential dislodgment of implanted electrodes with consequent loss of junction.
- First described in the contest of cardiac pacemakers
- Should be managed expeditiously so as to prevent displacement of the intracranial electrodes.
- Clinical presentation
- Complaining of straining extension cables with associated discomfort, but this is not an emergency and can be referred to the clinic of the operating surgeon.
DBS withdrawal symptoms
- Symptoms
- Motor
- Acute dyskinetic Parkinsonian or dystonic crises and deaths
- Non-motor
- Suicidal ideation
- Depression
- The more benefit the patient derived from stimulation the more marked withdrawal features may be.
- Long term DBS and advanced PD are probable risk factors.
- These can be difficult to manage and prompt recognition
- Involve an experienced neurologist
Stimulation side effects and suicide
- Acute depression
- Stimulation of the limbic components of deep brain basal ganglia structures
- Patients with suicide attempts and/or ideation should be admitted for multi/interdisciplinary care including neuropsychiatric input, and/or medication/stimulation adjustment
- A meta-analysis found that approximately 52% of cases with suicidal ideation and/or attempts were reported to complete suicide following DBS
- These patients are accordingly high risk and should be treated as such- not left to general liaison psychiatry management.
- Other stimulation related side effects
- Vary depending on the electrode location but may commonly include
- Dysarthria,
- Imbalance,
- Tonic muscle contractions,
- Paraesthesiae
- Visual disturbances.
- These can typically be managed with an urgent outpatient review for re-programming
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