Parkinson’s Disease

Parkinson’s disease is a progressive condition of the nervous system. It develops when nerve cells that produce dopamine (a chemical messenger that helps make movement smooth and automatic) gradually break down in a small area of the brain called the substantia nigra. As dopamine levels fall, movement becomes slower, smaller in scale, and harder to initiate.

By the time the first visible symptoms appear, a substantial number of these cells have usually already been lost. This is why Parkinson’s disease is often present for some time before diagnosis, and why care focuses on managing the condition effectively over time rather than on a single decisive treatment.

Parkinson’s disease is not the same as “parkinsonism.” Other conditions, including multiple system atrophy, progressive supranuclear palsy and drug-induced parkinsonism, can produce similar symptoms but respond very differently to treatment. Distinguishing between them is one of the most important parts of assessment, because the surgical options that help Parkinson’s disease do not help these other conditions.

No two patients experience Parkinson’s disease in exactly the same way, but a characteristic pattern of symptoms is usually recognizable:

• Resting tremor: shaking of a hand, jaw or leg, most noticeable when the limb is relaxed and supported
• Rigidity: stiffness that makes movement feel resisted
• Bradykinesia: slowness of movement, including smaller handwriting, a quieter voice and reduced arm swing while walking
• Postural instability: impaired balance and an increasing tendency to fall, usually appearing later in the condition
• Changes in speech and swallowing
• Non-motor symptoms: disturbed sleep, loss of sense of smell, constipation, low mood and, in later stages, changes in thinking or memory

Tremor is the symptom most people associate with Parkinson’s disease, but it is often slowness and stiffness that have the greatest effect on daily life — and a meaningful proportion of patients never develop a prominent tremor at all. Non-motor symptoms deserve attention too: sleep disturbance, low mood and constipation frequently appear years before the motor symptoms and can affect quality of life as much as the movement problems do.

Levodopa (a medication that replaces dopamine) remains the most effective treatment for Parkinson’s disease, and for the first years it often works very well. Over time, however, each dose tends to last a shorter time, and the gap before the next dose begins to show. Patients often describe their day in terms of “on” periods, when medication is working well, and “off” periods, when it is not.

Raising the dose can reduce “off” time, but it often brings on dyskinesia (involuntary, flowing movements that appear when medication levels peak). Patients can then find themselves caught between two unsatisfactory states, with a narrowing window in which they feel fully like themselves. This pattern (a real response to levodopa that no longer lasts long enough, with dyskinesia at higher doses) is one of the clearest signals that a surgical evaluation may be worthwhile. It is not a sign that treatment has been left too late; it is typically the stage at which deep brain stimulation was designed to help.

A surgical evaluation for Parkinson’s disease is typically considered when several of the following apply:

• A diagnosis of Parkinson’s disease for at least five years
• A clear, meaningful response to levodopa, but one that wears off sooner than it used to
• Involuntary movements (dyskinesia) related to the higher medication doses now needed
• Tremor that has not responded adequately to medication
• No severe, uncontrolled psychiatric illness and no significant memory or thinking difficulties
• General health sufficient for a planned neurosurgical procedure

Candidacy is always decided on an individual basis, following full neurological and, where appropriate, neuropsychological assessment.

The main surgical option for Parkinson’s disease is deep brain stimulation, in which thin electrodes are placed in a precisely targeted area of the brain and connected to a small, implanted pulse generator. Continuous, adjustable electrical stimulation helps to regulate the abnormal brain signaling responsible for tremor, stiffness and slowness. Full details of the DBS procedure are described on our Deep Brain Stimulation page.

For patients whose main problem is a medication-resistant tremor rather than the broader motor picture of Parkinson’s disease, MR-guided focused ultrasound (MRgFUS) may also be considered. This is described on our MRgFUS page.

Surgery does not replace medication. In most patients it allows medication to work better, often at a lower and steadier dose, and it does not remove the ongoing value of physical therapy.

Assessment before any surgical decision typically includes:

• A detailed history of symptom onset and progression, and a full current medication list
• Neurological examination using standardized motor rating scales
• Levodopa response testing: assessing motor symptoms both “on” and “off” medication, since the pattern of response is one of the strongest predictors of how a patient may respond to DBS
• High-resolution brain MRI
• Neuropsychological and mood assessment, which is a routine and necessary part of evaluation before DBS
• Blood tests and other investigations to exclude other contributing causes

Deep brain stimulation does not cure Parkinson’s disease and does not stop it from progressing. In appropriately selected patients, it can help to:

• Lengthen the “on” periods when medication is working well
• Reduce tremor, rigidity and slowness during those periods
• Reduce medication-induced involuntary movements (dyskinesia)
• Allow a meaningful reduction in overall daily medication dose, in many cases

Treatment goals vary between patients, and individual results may differ. Symptoms that are less likely to improve include balance problems that persist even in the best “on” state, freezing of gait that does not respond to medication, and cognitive symptoms. Being clear about this distinction before surgery is central to setting realistic expectations.

Deep brain stimulation is a neurosurgical procedure and carries real, though uncommon, risks, including bleeding within the brain, infection around the implanted hardware, lead movement or fracture, seizure, and stimulation-related side effects such as changes in speech, balance or mood. Many stimulation-related side effects can be reduced or resolved through reprogramming, which is one practical advantage of a reversible, adjustable system. Individual risk depends on age, overall health and other factors, and is discussed in detail during consultation rather than presented as a single figure that applies to everyone.

Recovery and device programming are described in full on our Deep Brain Stimulation page. In general, stimulation is not switched on immediately, and programming is carried out gradually over several sessions in coordination with adjustments to medication. Ongoing physical therapy, and structured long-term follow-up, are an integral part of care after surgery rather than an optional extra.