When a patient has a grand mal seizure, also called a generalized tonic-clonic seizure, she experiences a loss of consciousness and muscle control. MedlinePlus explains that patients have muscle contractions and may bite their tongues or cheeks during the seizure. Changes to the brain's electrical activity cause the seizures, disrupting how the brain communicates. With a grand mal seizure, the abnormal electrical activity occurs on both the left and right brain hemispheres.
Injuries to the Brain
The Mayo Clinic's website notes that when the brain becomes injured, either through an accident or illness, a grand mal seizure can occur. One type of brain injury that can cause a seizure is an anoxic brain injury, which results from a lack of oxygen. The decrease in oxygen levels affect the functioning of brain cells. Accidents, like a near drowning incident, or exposure to toxins, such as with carbon monoxide poisoning, can result in an anoxic brain injury. Certain health conditions, such as a stroke and abnormal heart rhythms, can also injure the brain and result in grand mal brain seizures. Traumatic brain injuries, in which an impact damages the brain, can disrupt the brain's electrical activity.
Low Levels of Nutrients in the Blood
If a person has very low levels of certain nutrients in his blood, he can have grand mal seizures, according to the Mayo Clinic's website. For example, if a person has uncontrolled diabetes with low levels of glucose, or sugar, in his blood, then he may have grand mal seizures. Low levels of magnesium, calcium, sodium or vitamin B6 may also result in grand mal seizures. The Merck Manual Home Edition points out that this cause of grand mal seizures commonly occur in patients under age two.
Brain Infections
Certain brain infections can interfere in the brain's electrical activity. Examples of infections that can cause grand mal seizures include encephalitis, meningitis, brain abscess, toxoplasmosis, malaria, tetanus, syphilis, rabies and AIDS. The Mayo Clinic's website notes that a history of one of these infections can also cause grand mal seizures.
Drugs and Alcohol
People who use drugs or alcohol may have grand mal seizures. The Mayo Clinic's website explains that withdrawal can also cause grand mal seizures. Examples of drugs that cause this type of seizure through withdrawal include sedatives, like sleep medications and general anesthetics used for surgery. Amphetamine use or an overdose of cocaine can trigger a grand mal seizure. The Merck Manual Home Edition adds that an overdose of a tricyclic antidepressant may cause a seizure.
Other Causes
Other medical conditions may cause a grand mal seizure. For example, patients who have structural problems in the blood vessels in their brain can have grand mal seizures, according to the Mayo Clinic's website. If an abnormality in the blood vessel results in a rupture, the bleeding in the brain can disrupt the electrical activity. Brain tumors, both cancerous and noncancerous growths, may cause grand mal seizures if they interfere in the brain's electrical communication. Genetic syndromes can also affect the structure of the brain, resulting in the seizures. The genetic syndromes include metabolic disorders, like Tay-Sachs disease.
