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. The authors of Reference 1 report that the optimum choice of anti-epileptic drugs and duration of treatment is not clear.
In population-based studies of 1,843 MS patients, 59 developed seizures after the diagnosis of multiple sclerosis, while 11 developed seizures before the MS diagnosis. It is not clear whether the two conditions were related in those patients who developed seizures first.
The Mayo Clinic web site recommends medical advice for anyone who experiences a first seizure.
References:
1. Kelley BJ et al, “Seizures in patients with multiple sclerosis: Epidemiology, pathophysiology and management”, CNS Drugs. 2009; 23(10): 805-815.
2. More information on seizures:
http://www.mayoclinic.com/health/epilepsy/DS00342
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.