What Tests Are Required Before DBS Surgery?
In brief
Evaluation for deep brain stimulation is not based on a single scan or examination. It usually includes confirmation of the Parkinson’s diagnosis, an assessment of medication response, brain imaging, cognitive and psychological testing and a general medical review.
The purpose is to determine whether DBS is likely to address the patient’s main symptoms and whether surgery can be performed safely.
Evaluation by a movement-disorders neurologist
The first step is usually a detailed review by a neurologist experienced in movement disorders.
The assessment considers:
Whether the diagnosis is consistent with Parkinson’s disease
Which symptoms improve with medication
The duration and severity of “off” periods
Dyskinesia and medication side effects
Tremor, rigidity and bradykinesia
Gait, balance, speech and swallowing
The patient’s expectations from DBS
Symptoms that do not respond to levodopa, particularly longstanding balance, speech or swallowing problems, may also be less likely to improve with DBS.
What is the levodopa challenge test?
During a levodopa challenge, motor symptoms are evaluated in an “off-medication” state and again after an appropriate dose of levodopa.
The team compares tremor, stiffness, slowness and movement scores between the two examinations. A clear levodopa response generally supports the expectation that DBS may improve similar motor symptoms, although tremor can sometimes respond to DBS even when medication response is limited.
Medication should only be withheld according to the DBS centre’s instructions.
Why is neuropsychological testing performed?
Neuropsychological testing assesses areas such as:
Memory
Attention
Language
Problem-solving
Processing speed
Mood and behaviour
The aim is not to “pass or fail” an intelligence test. It is to identify cognitive or psychological factors that may affect surgical suitability, target selection, informed consent and postoperative support.
Preoperative neuropsychological assessment is strongly recommended as part of DBS evaluation.
Is a brain MRI required?
Brain MRI is commonly used to:
Exclude unexpected structural abnormalities
Assess brain anatomy
Identify significant atrophy or vascular changes
Plan the electrode target and safe trajectory
A CT scan may also be obtained for surgical planning, frame localisation or MRI–CT fusion. The exact imaging protocol varies between DBS centres.
What other medical tests may be needed?
Depending on age and medical history, evaluation may include:
Blood tests
Electrocardiogram
Chest imaging when indicated
Anaesthesia assessment
Review of anticoagulants and other medications
Infection screening
Additional cardiology or respiratory assessment
These investigations assess the safety of anaesthesia and surgery rather than the likely neurological benefit of DBS.
Who makes the final decision?
The results are usually reviewed by a multidisciplinary team that may include:
A movement-disorders neurologist
A functional neurosurgeon
A neuropsychologist or psychiatrist
An anaesthesiologist
Specialist DBS nurses and programming staff
In my discussions with patients, I emphasise that these tests are not unnecessary barriers. Each one answers a different question: whether DBS can help, whether it can be performed safely and how treatment should be individualised.
What should an international patient prepare?
Patients seeking assessment from another country should ideally provide:
Neurology reports
Current medication list with doses and timing
Previous brain MRI images
Videos showing “on” and “off” periods when requested
Prior cognitive or psychiatric reports
Relevant medical and surgical history
An online review can help organise the process, but it does not always replace the examinations required before surgery.
Frequently asked questions
Does a good levodopa response guarantee a good DBS result?
No. It is an important indicator, but target accuracy, symptom profile, cognition, programming and disease progression also influence outcomes.
Can DBS be performed without neuropsychological testing?
Protocols differ, but cognitive and psychological assessment is strongly recommended before proceeding.
How long does the evaluation take?
It may be completed over one or several visits depending on the centre, required tests and whether the patient is travelling internationally.
Conclusion
Preoperative DBS assessment combines neurological, cognitive, psychological, imaging and general medical information.
The aim is not simply to confirm that surgery is technically possible. It is to determine whether DBS addresses the patient’s priorities and whether the expected benefits justify the individual risks.
Dr Kaan Tuğberk ÖzdemirNeurosurgeon – İzmir, Türkiye
This article provides general information and does not replace an individual multidisciplinary DBS assessment.
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