Multiple Sclerosis (MS) is a chronic disease affecting the central nervous system, including the brain and spinal cord. MS causes the immune system to mistakenly attack the protective layer around nerve fibers, a process called demyelination. Seizures are sudden, uncontrolled electrical disturbances in the brain that cause changes in behavior, movements, feelings, and consciousness. While seizures are not a universal symptom of MS, the disease increases an individual’s susceptibility to experiencing them.
Establishing the Connection
Seizures are observed more frequently in the MS population compared to the general public. Studies indicate that people with MS are approximately two to three times more likely to experience seizures than those without the condition. While the prevalence of epilepsy (recurrent unprovoked seizures) is around 0.76% to 3% in the general population, it rises to an estimated 2% to 5% among individuals with MS.
The occurrence of seizures is often linked to the extent of overall brain damage associated with MS. Patients with a higher burden of brain lesions, as seen on magnetic resonance imaging (MRI), have a greater likelihood of experiencing a seizure event. The risk also appears to be higher in those with a longer disease duration or a more progressive form of MS.
Seizures may manifest at any point in the disease course. In some rare instances, a seizure can be the first noticeable neurological event before a formal MS diagnosis is established.
The Neurological Basis of Seizures
The connection between MS and seizures is rooted in physical damage to brain tissue. MS lesions, particularly those in or adjacent to the cerebral cortex (the brain’s outer layer), are strongly implicated in triggering epileptic activity. These lesions can act as epileptogenic foci, which are areas of brain tissue capable of generating seizures.
The process of demyelination and the subsequent inflammatory response disrupt the brain’s normal inhibitory and excitatory balance. Scar tissue, known as gliosis, forms around the MS plaques, altering the pathways through which electrical signals travel. This structural damage can impair the normal dampening mechanisms, leading to a state of neuronal hyperexcitability.
Specific support cells, called astrocytes, also play a role. Astrocytes maintain the environment around neurons, regulating water, potassium ions, and neurotransmitter levels. Research suggests that in MS patients with seizures, astrocytes show reduced ability to perform these regulatory functions, promoting an imbalance that favors electrical over-firing.
Identifying Seizure Types and Triggers
The type of seizure experienced by an MS patient is typically determined by the location of the causative MS lesion. Focal seizures, which begin in one specific part of the brain, are the most common type observed. These focal seizures can manifest as focal aware, where the person remains conscious, or focal impaired awareness, where consciousness is altered.
In some cases, a focal seizure can quickly spread across the entire brain, resulting in a focal to bilateral tonic-clonic seizure (formerly known as a grand mal seizure). Approximately 60% of MS patients who experience seizures have these focal types.
While the underlying MS lesion provides the vulnerability, external factors can act as immediate triggers for a seizure event. These factors can lower the seizure threshold in susceptible individuals:
- Severe fatigue
- Emotional stress
- Acute infections that cause a high fever
- Lack of adequate sleep
- Significant changes in electrolyte balance
It is important to distinguish epileptic seizures from paroxysmal symptoms. These are sudden, short-lived neurological events caused by temporary nerve misfiring rather than abnormal electrical discharges. Examples include tonic spasms or sudden, stabbing pain, which may be treated with anti-seizure medications despite not being true epileptic events.
Therapeutic Approaches
The management of seizures in the context of MS generally follows the same principles as treating epilepsy in the general population. Anti-epileptic drugs (AEDs) are the standard course of treatment for controlling seizure activity. Commonly prescribed AEDs include levetiracetam, lamotrigine, and carbamazepine.
The choice of medication must be individualized, taking into account potential interactions with a patient’s existing MS disease-modifying therapies (DMTs). Since some AEDs may exacerbate common MS symptoms like fatigue or cognitive slowing, a careful balance is sought to minimize side effects.
Treatment may also involve addressing underlying seizure triggers, such as ensuring proper sleep hygiene and managing fever or infection aggressively. In cases where seizures are directly linked to an acute MS relapse, treating the relapse with standard therapies, such as corticosteroids, may help resolve the seizure activity.
The goal of therapy is to achieve seizure freedom with a well-tolerated medication that does not negatively interact with other necessary MS treatments. Regular monitoring and follow-up with a neurologist are necessary to adjust the treatment plan as the disease evolves.