Patients with multiple sclerosis have seizures at two to three times the rate of the age-matched general population. A report from the Mayo Clinic encourages physicians to be alert to the possibility. Seizures do not indicate a worse prognosis for multiple sclerosis (MS); clinical observations show no correlation between frequency of seizures and length or severity of MS. The causes may include:
1. Side effects of medications used to treat MS symptoms. Interferon-beta medications (Avonex and Rebif), Glatiramer acetate (Copaxone), GABA-B agonists (Baclofen), and aminopyridines may cause seizures in rare cases.
2. Demyelination of the cortical neurons.
3. Inflammation in the cortex.
4. Edema (excess fluid) associated with MS lesions.
Seizures can affect any process that is coordinated by the brain. The symptoms range from mild changes in sensations up to unconsciousness and convulsions. They are classified as follows:
1. Simple partial seizures, characterized by changes in sensation and possibly involuntary jerking movements.
2. Complex partial seizures, characterized by altered consciousness and loss of awareness. Staring into space and non-purposeful motions are common.
3. Absence seizures (petit mal). These cause staring and subtle body movements, and often loss of consciousness.
4. Myoclonic seizures, with sudden jerks of the arms and legs.
5. Atonic seizures, which cause falls from a sudden loss of muscle tone.
6. Tonic-clonic seizures (grand mal). These are the most intense type, characterized by loss of consciousness, shaking, and loss of bladder control.
Partial seizures are more common in multiple sclerosis patients, and cleared up spontaneously in nearly half the patients in a recent study. However, even mild seizures can affect quality of life, and can be dangerous during certain activities such as driving. Anti-epileptic medication is effective for many, but the response is variable. These drugs may have more side effects in MS patients than in others, partly because of interactions with other drugs prescribed for MS symptoms.