Deep brain stimulation in Parkinson’s: patient selection, pathways and pitfalls

Webinar summary

Deep brain stimulation (DBS) has become an established therapy for people with Parkinson’s disease whose symptoms can no longer be adequately managed with medication alone.

But how can teams select the right candidates, how can they prepare them for the process, and what can go wrong?

Patient selection

NICE guidelines recommend DBS be offered to people with advanced disease whose symptoms are “not adequately controlled” by the best medical therapy.

Nicola Pavese, professor of clinical neuroscience at Newcastle University, outlined the 5-2-1 criteria, which have been proposed as a method to recognise advanced Parkinson’s. The patient, he explained, has advanced disease, and may be considered for DBS, if they meet one of the following:

• taking levadopa at least five times a day
• having at least two hours with OFF symptoms a day
• having at least one hour of troublesome uncontrolled dyskinesia a day

DBS candidates should also have at least four to five years of disease duration, to ensure they have a correct diagnosis. They should also either be experiencing bothersome symptoms, despite taking high-doses of medications, or significant side effects.

“One important thing is that patients still need to respond to dopaminergic medications. DBS does the same as a large dose of dopaminergic medication, so unless there is a good response to medications, DBS is not going to help,” said Nicola, adding that tremor was the only exception.

“Very often, tremor is not responsive to dopaminergic medication, but still responds very well to DBS.” In this scenario, clinicians can consider DBS if the tremor is medication refractory and interfering with quality of life.

DBS should not be considered if the person is not fit for surgery and being over 75 years old.

Moderate cognitive impairment, the presence of gait and balance problems in the ON state, and poor ON states are all contraindications. “They do not improve with DBS, and can get worse,” said Nicola.

Pathway from referral to surgery

In the UK, there are 17 centres providing DBS surgery, and a multidisciplinary team (MDT) approach is the gold standard. “DBS nurses play a central role in the patient pathway, from pre-DBS assessment through surgery and life-long care,” said Joseph Candelario-Mckeown, DBS nurse specialist, at University College London Hospitals

The first appointment, he explained, is usually a consultation with a neurology consultant. They will establish the patient’s suitability for DBS, consider the potential target, and refer them for a pre-procedure assessment with a DBS nurse specialist.

At the pre-procedure assessment, the nurse specialist will get to know the patient. They will establish the main symptoms that impact on the person’s quality of life, their psychosocial, and cognitive status.

The nurse will also ensure the patients has been given written information about the levodopa challenge test, which involves a 12-hour wash out period and predicts the likely benefit of DBS.

Investigations include a range of scales and questionnaires, such as PDQ-39, MDS UPDRS, and the Parkinson’s sleep scale, as well as neuropsychology assessment, MRI, and speech therapy assessment.

“If the patient has psychiatric issues, we refer them to psychiatrists before we put them forward to the MDT,” said Joseph.

The next step is an MDT consultation, during which the levadopa challenge test, neuropsychology, and MRI results are reviewed, and any red flags discussed. If they decide to offer the surgery, they determine the appropriate target and discuss the potential side effects and surgical complications.

Surgical candidates are then seen in a nurse-led, pre-surgical consultation. At admission, dopamine agonist and anticholinergic medications are withheld, and an NGT is inserted for the intra-operation administration of levadopa. Medications are restarted as soon as the patient wakes up.

What can go wrong?

Moving on to talk about the potential pitfalls, Antonella Macerollo, consultant neurologist at The Walton Centre in Liverpool, said a device compatibility issues were very rare, but significant. They include, for example, hypersensitivity or allergic reactions to the device’s metal components or insulating materials. In most cases, the device is completely removed.

Lead migration and electrode deformation may also occur, resulting in reduced efficacy.

The post-DBS surgery management is complex, Antonelle went on. “The most important challenge after surgery is working on the balance of increasing the simulation and reducing the pharmacological therapy. It requires several adjustments, including possible failures.”

There may be periods where non-motor symptoms, such as depression and low mood, worsen before they improve. Ensuring patients and their families are aware of these challenges from the outset helps set realistic expectations, she added.

Side effects tend to be surgery-related, such as infection, oedema, pain and swelling or skin erosion at the surgical site, or, in rare cases, seizures.

Stimulation-related side effects can include muscle spasms, paraesthesia, dysarthria, and problems with balance. Antonelle said: “All these side effects related to the stimulation can be improved with stimulation adjustments.”

Many patients gain weight following the surgery, especially if they were severely dyskinetic beforehand, as they are using fewer calories on a daily basis. And, in rare cases, patients do not respond to the device.

Managing expectations

Preparing people for DBS is as much about managing expectations as it is clinical assessments.

It is important, Antonelle said, to ensure patients are aware that it is not a cure, that they understand the risk and the potential side effects, and that they are not expecting a “quick and effortless improvement”.

“An MDT approach is fundamental. The nurses, the physios, and the therapists, together with the neurologist and the neurosurgeon, need to be involved.

“It is important to explore the patient's priorities and the goal of the DBS, for example, motor fluctuation and dyskinesia. It is important the goals of clinician and the priority of the patients match. If this can be clarified before the surgery, it is the most important step,” said Antonelle.