Glioblastoma is an aggressive form of brain cancer characterized by its rapid growth and infiltration into surrounding brain tissue. One of the most common symptoms is the occurrence of seizures—sudden, uncontrolled electrical disturbances in the brain. Seizures can be the first sign of the cancer, leading to its initial diagnosis. The tumor’s presence disrupts the brain’s normal functions, and managing these seizures becomes a parallel challenge alongside primary cancer treatment.
Understanding Why Glioblastomas Trigger Seizures
A primary cause is the tumor’s physical presence and growth. As the mass expands, it exerts pressure on and irritates healthy neurons. This irritation is compounded by peritumoral edema (swelling in the surrounding tissue), which increases intracranial pressure and makes seizures more likely.
The tumor is not a contained mass; its cells actively infiltrate healthy brain tissue. This infiltration disrupts the organized neuronal networks responsible for normal brain function. This creates pathways for disorganized electrical signals to propagate.
Glioblastomas also create neurochemical imbalances. The tumor and surrounding cells can release excessive amounts of glutamate, an excitatory neurotransmitter, while reducing gamma-aminobutyric acid (GABA), the brain’s primary inhibitory neurotransmitter. This shift towards excitation over inhibition lowers the seizure threshold.
The tumor’s high metabolic demand changes local blood flow and can compromise the blood-brain barrier. This barrier normally protects the brain, but it becomes leaky near the tumor. This breakdown allows substances to enter the brain, contributing to inflammation and neuronal irritation that can trigger seizures.
Identifying Seizure Activity in Glioblastoma Patients
Seizures in glioblastoma patients vary depending on the tumor’s location and size. A common type is the focal seizure, originating in one area of the brain. These may involve involuntary jerking of a limb, sensory changes like strange smells, or emotional shifts, and can occur with or without a loss of awareness. If the electrical disturbance remains localized, the person might remain fully conscious but unable to control the symptoms.
When seizure activity spreads to both sides of the brain, it is a generalized seizure. The most recognized type is the tonic-clonic seizure, where a person loses consciousness, their body stiffens, and they experience jerking muscle contractions. Some seizures are more subtle, presenting as moments of staring or confusion that can be mistaken for cognitive changes from the tumor itself.
A detailed account from the patient or a caregiver helps identify the seizure type and its origin. To confirm the diagnosis, physicians use an electroencephalogram (EEG), which records the brain’s electrical signals via scalp electrodes. This test allows neurologists to see the characteristic patterns of a seizure.
Neuroimaging helps correlate seizure activity with the tumor. Magnetic resonance imaging (MRI) and computed tomography (CT) scans show the glioblastoma’s location, size, and any surrounding swelling. Mapping the EEG findings to the tumor’s location on an MRI can confirm the glioblastoma is the cause of the seizures.
Managing Seizures in the Context of Glioblastoma
The primary management for glioblastoma-related seizures is antiepileptic drugs (AEDs), with the goal of controlling seizure activity with minimal side effects. Clinicians select an AED carefully, considering potential interactions with chemotherapy agents, like temozolomide, and radiation therapy.
Side effect profiles are a major consideration, as some AEDs cause fatigue, dizziness, or cognitive slowing, which can overlap with tumor symptoms. For instance, levetiracetam is a common AED that can cause mood changes or irritability. The choice of medication is tailored to the individual, balancing seizure control against potential side effects.
Whether to use AEDs prophylactically—to prevent a first seizure—is a subject of clinical debate. Current guidelines do not recommend giving these drugs to every patient upon diagnosis. This approach avoids exposing patients who may never have a seizure to the potential side effects of the medication.
Treatments aimed directly at the tumor also help manage seizures. Surgical resection to remove as much of the tumor as safely possible can alleviate pressure and reduce or eliminate seizures. Radiation and chemotherapy can also decrease seizure frequency by shrinking the tumor and reducing inflammation.
In rare situations where seizures are prolonged or occur in rapid succession, a condition known as status epilepticus, immediate medical intervention is required to stop the seizure and prevent brain damage.
Living with Glioblastoma and Seizures: Impact and Support
Living with glioblastoma and seizures presents significant challenges. The unpredictability of seizures can impact a patient’s quality of life, compounding the difficulties posed by the cancer. This can lead to a loss of independence, particularly the ability to drive, as jurisdictions require a seizure-free period before driving is permitted. This restriction can create feelings of isolation and dependence on others for transportation.
Beyond the physical event, the condition can affect cognitive function, memory, and mood. Patients may experience increased fatigue and difficulty with concentration. The fear of having a seizure in public can lead to social withdrawal and anxiety, causing patients to avoid activities they once enjoyed.
Navigating these challenges requires a multidisciplinary care team. This team includes neuro-oncologists, neurologists, nurses, social workers, and therapists who work together to manage both the cancer and its symptoms. This integrated approach addresses medical needs alongside emotional and practical support.
Supportive care is important for patients and their families. This includes education on seizure safety precautions, such as creating a safe environment to minimize injury. Support groups and counseling can provide a space for patients and caregivers to share experiences and coping strategies, while reliable educational materials help empower individuals to be active participants in their care and make informed decisions.