Parkinson’s Disease (PD) is a progressive neurological disorder known for its impact on motor function, causing tremors, stiffness, and slow movement due to the loss of dopamine-producing neurons. Seizures are sudden, uncontrolled electrical disturbances that disrupt normal nerve cell communication, resulting in changes in behavior, movement, or consciousness. While PD is not typically classified as a primary cause of epilepsy, the co-occurrence of seizures in PD patients is a serious clinical concern. The risk of experiencing a seizure is often related to the underlying disease pathology, the medications used to manage PD symptoms, or other co-existing health conditions.
The Relationship Between Parkinson’s and Seizure Activity
The relationship between Parkinson’s and seizure activity is generally considered an association rather than a direct cause-and-effect link. Studies indicate that individuals with PD have a significantly higher risk of experiencing seizures compared to the general population, suggesting that the neurodegenerative process of PD may lower the brain’s seizure threshold. The underlying neurodegeneration extends beyond the dopamine-producing cells, leading to widespread neural vulnerability. The abnormal accumulation of the protein alpha-synuclein into Lewy bodies, a hallmark of PD, can affect cortical regions and potentially increase neuronal excitability. This pathological process, combined with a disrupted balance of neurotransmitters like dopamine and gamma-aminobutyric acid (GABA), creates a brain environment more susceptible to disorganized electrical activity.
Medication Side Effects as a Potential Trigger
A relevant cause of seizures in Parkinson’s patients is related to the medications used for symptom management. Several antiparkinsonian drugs can lower the seizure threshold, especially when present at high concentrations or when abruptly stopped.
Amantadine, used to treat dyskinesia and motor symptoms, is known to rarely precipitate or worsen seizure activity. Since the drug’s elimination relies on kidney function, patients with renal impairment risk drug accumulation and toxicity, which can lead to seizures and even status epilepticus. High-dose use of Carbidopa-Levodopa presents another complex mechanism. Carbidopa can bind to Vitamin B6 (pyridoxine), a cofactor necessary for producing the inhibitory neurotransmitter GABA, and high doses can lead to a functional deficiency, provoking seizures. Furthermore, sudden reduction or discontinuation of dopaminergic agents, such as dopamine agonists, can trigger Dopamine Agonist Withdrawal Syndrome, which may destabilize the central nervous system.
Underlying Neurological Conditions and Systemic Causes
Seizures in PD patients are often an acute symptomatic event caused by a co-existing neurological or systemic issue, common in an older patient population. Vascular events, such as mini-strokes or cerebral ischemia, are a significant cause of seizures in this demographic. The resulting damage to brain tissue can create an epileptogenic focus, causing seizures independently of the PD pathology.
Severe neurocognitive decline and dementia are also linked to an elevated seizure risk in PD patients. The widespread neurodegeneration associated with dementia increases the brain’s susceptibility to seizures. Systemic metabolic disturbances, including severe electrolyte imbalances or episodes of low blood sugar, can also acutely disrupt brain function and trigger a seizure.
Diagnosis and Treatment Approach
Diagnosing a seizure in a PD patient can be challenging because certain PD-related motor features, such as severe dyskinesia or tremor, can mimic seizure activity. Clinicians rely on diagnostic tools to differentiate between a true seizure and complex movement disorders. An electroencephalogram (EEG) is a standard tool used to record the brain’s electrical activity during a suspected event. Brain imaging, such as an MRI, is also performed to identify structural causes like a recent stroke, tumor, or evidence of infection.
The primary treatment principle is to first identify and address the underlying cause. This may involve adjusting PD medication dosages, treating an infection, or stabilizing metabolic imbalances. Standard anti-epileptic drugs (AEDs) are typically reserved for confirmed epilepsy or unprovoked seizures, as some AEDs can potentially worsen PD motor symptoms.