Generalized tonic-clonic seizures (GTCS), or grand mal seizures, are one of the most recognized seizures. GTCS are considered generalized seizures that cause bilateral, convulsive muscle contractions and can occur in two distinct phases:

Tonic: the sudden stiffness of muscles 

Clonic: rhythmic jerking of the limbs GTCS are caused by sudden excessive electrical activity that occurs simultaneously in both hemispheres of the brain.

Since the entire brain is involved with no focal onset of the seizure, GTCS will most times generate full-body contortions and usually include a brief loss of consciousness. GTCS is typically a significant form of epilepsy; especially if repeated over time without a known cause. GTCS are distinct from focal seizures, which occur when the seizure originates from a focal point in the brain because GTCS involve the entire brain, which creates a more extensive and vigorous widespread tonic-clonic response.

The standard duration of a GTCS is between one and three minutes in duration. If a seizure lasts longer than five minutes, it is a medical emergency and immediate medical attention should be sought. A seizure that lasts longer than five minutes or if three or more seizures occur sequentially without complete recovery is in a state known as status epilepticus. Status epilepticus is life-threatening emergency that requires urgent medical treatment in the hospital unless rescue medication is taken shortly after the seizure occurred and successfully ends the seizure. Typically, one lone GTCS episode does not require ongoing medical treatments, but recurrent GTCS episodes reliably indicate epilepsy and will more likely than not require daily anti-epileptic medications to control and prevent future episodes. 

Though they can be very frightening to witness, by having medical treatments, safety precautions, and lifestyle modifications, they can be controlled. Knowing the causes, symptoms, and treatments for GTCS makes it easier to keep under control and improve the quality of life for those affected.

Generalized tonic-clonic seizure (GTCS) can have a wide range of underlying conditions and can occur in any age group. While some RTCS arise from identifiable medical conditions, in some cases no defined cause is found, and these are referred to as idiopathic seizures. Being aware of potential causes helps with the diagnosis and management of the condition. The most commonly known causes of GTCS are outlined below:  

1. Genetics: Some GTCS are inherited especially in younger individuals. Some types of epilepsy run in families due to mutations in certain genes affecting the way neurons transmit signals in the brain. In these situations, an individual may have a genetic susceptibility that makes them more likely to have seizures even if they are not stressed.  
2. Traumatic Brain Injury: Injury to the brain from accidents, falls, birth injuries or neurosurgical injuries has the possibility to create structural damage or scar tissue in the brain which can block or change the way electrical impulse travel in the brain and create seizures.  
3. Brain Tumors: Both malignant and benign neck tumors can irritate surrounding brain tissue and change normal neurologic function leading to seizures. In some cases, a tonic-clonic seizure may be the first symptom of a brain tumor that was undiagnosed at the time of the seizure.
4. Stroke: The cause of seizures might be stroke, notably when lobar or both hemispheres are involved (seizures can occur as an immediate or delayed complication months or years post stroke.
5. Central Nervous System Infections: Central nervous system infections such as meningitis, encephalitis, and neurocysticercosis (a parasite that infects the brain) can cause seizures by direct destruction, irritation and/or scarring of the brain tissue. Prompt treatment of CNS infections is essential to avoid long-term complications from these infections.
6. Metabolic Disturbances: Seizures can be triggered by disruptions in the body’s internal chemical states. Common metabolic disease triggers are:
   • Hyponatremia (low sodium)
   • Hypoglycemia (low blood sugar)
   • Hypocalcemia or hypomagnesaemia (low calcium or low magnesium)
   • Kidney or liver failure causing accumulations of toxins that can affect brain functions
7. Drug or Alcohol Withdrawal: Withdrawals from alcohol, benzodiazepines or other recreational drugs after chronic use can lead to seizures. Withdrawals are most common during the detoxing or withdrawal phases and may need medical supervision.
8. Lack of Sleep or Stress: Both acute and chronic sleeping deprivation can decrease the seizure threshold in individuals who are already vulnerable to seizures. Psychological stress, emotional stress, trauma or extreme fatigue can lead to an increased risk of having a seizure, even in those without a previous diagnosis of epilepsy.
9. Congenital or Developmental Abnormalities: Abnormal structural brain anomalies that occur during fetal development or infancy (for example, vascular malformations or abnormality of brain formation) can increase the chances of having seizures later on. Structural anomalies can be identified through neuroimaging studies.
10. Cardiac Factors: Certain heart rhythm problems (arrhythmias), especially those that decrease blood flow to the brain, can result in loss of consciousness or have been known to cause seizures. Rarely, seizures can be provoked by cardiac problems versus neurologic.
11. Toxic or Poisoned: Collectively, all known toxic agents such as carbon monoxide, lead or other heavy metals have the potential to adversely affect the nervous system and result in seizures. Conditions of poisoning (either accidental or environmental) should always be considered in unexplained cases.
12. Hormonal Factors: Hormonal changes have been known to induce seizures. One specific example is catamenial epilepsy, where seizures are more prevalent at certain times in the menstrual cycle due to changes in estrogen and progesterone levels.

Generalized tonic-clonic seizures (GTCS) develop in different ways and, depending on the cause, when they develop may vary.

In genetic epilepsy syndromes, seizures often develop in childhood or adolescence, and usually without identifiable excitement. These seizures develop due to heritable Epileptogenic susceptibility of the brain, making it more likely to sustain abnormal electrical discharges.

Acquired epilepsy can develop at any age and is due to (for example) head injuries, brain infections and/or lesions in the brain, brain tumors or stroke. A person who has had no history of experiencing seizures may all of sudden develop seizures after a traumatic event such as a head injury or stroke.

Provoked seizures are seizures that result from an identifiable event, such as a child developing a single high fevers seizure along with the illness (febrile seizures), drug or alcohol withdrawal seizures, or metabolic related alterations (such as very low sodium or low glucose levels in the blood).

The presence of a single provoked seizure does not constitute an epilepsy diagnosis, however, a series of recurrent unprovoked seizures is usually sufficient for an epilepsy diagnosis.

In rare cases seizures arise as a result of autoimmune disorders (such as autoimmune encephalitis), or develop from no identifiable cause, which is referred to as idiopathic seizures.

Generalized tonic-clonic seizures (GTCS) usually observe highly dramatic and easily identifiable signs. Along with the seizure, many people undergo aura symptoms, which are senses rather than sensations, including experiences such as visual, taste, and smell changes, along with hallucinations or dizziness.

GTCS has two main phases, which are tonic and clonic, and one recovery phase called postictal phase.

 Tonic Phase (10-20 seconds):

• Onset of sudden loss of consciousness and possible fall
• Stiffness of limbs and body
• Temporary pause of breathing that may cause cyanosis of lips or face (blue)
• Yelling out or moaning (forcing air out of lungs) 
• Eyes rolling back in head or fixed in one position
• Jaw may lock or grind teeth  

Clonic Phase (1-2 mins or less):

• Jerking of arms and legs rhythmically
• Bitten tongue or bit inside of cheeks
• Loss of bowel or bladder control
• Frothing or foam from mouth

Postictal Phase (up to thirty minutes or longer):

• Confusion or disorientation
• May sleep deeply or great fatigue
• Headaches & muscle soreness
• Temporary amnesia 
• Difficulty speaking or organizing thoughts

Todd’s Paralysis: This refers to temporary weakness on one side of the body following a seizure. The weakness can last from a few minutes to several hours. While the seizure itself typically lasts 1 to 3 minutes, recovery time varies by individual. If a seizure lasts longer than 5 minutes, or if multiple seizures occur without a return to awareness between them, it is known as status epilepticus—a serious medical emergency.

A full medical assessment is needed to diagnose generalized tonic-clonic seizures (GTCS) and determine the cause and classification of the seizure and exclude other possible etiologies. A typical evaluation process is as follows: 

1. Medical History: The physician will perform a thorough review of the patient’s medical history, including the following information:
   • Number, frequency, length of seizures
   • Description of event (often from witnesses)
   • Any warning signs or auras of a seizure
   • Family history of epilepsy or other neurological conditions
   • Any possible seizure triggers, including stress, lack of sleep, previous substance use
2. Neurological Exam: The examination identifies any evidence of possible underlying brain or nervous system disorders. A complete neurological exam assesses:
   • Reflexes
   • Muscle strength
   • Coordination and balance
   • Sensory function
   • Cognitive function
3. Electroencephalogram (EEG): An EEG reports the electrical activity in the brain. In people with GTCS, the EEG may show generalized spike-and-wave discharges. EEG will help with several aspects of the patient’s evaluation, including: 
   • Confirming the diagnosis of epilepsy   
   • Identifying the type of seizure
   • Providing treatment direction
4. Brain Imaging:
   • MRI (Magnetic Resonance Imaging): Preferred technique to identify structural abnormalities (tumors, scarring, malformations, previous injury).
   • CT scan (Computed Tomography): Commonly used in emergency settings to identify acute findings (bleeding, cysts, and tumors).
5. Blood and Urine Tests: Tests used to identify metabolic derangement (metabolic causes), infectious problems (infectious causes), or exposure to toxic medications or substances that could elicit seizures.
6. Lumbar Puncture (Spinal Tap): If there is concern for an infection such as meningitis or encephalitis, cerebrospinal fluid could be analyzed through a lumbar puncture.
7. Positron Emission Tomography (PET): A PET scan may be ordered to identify the existence of abnormal brain function and can help localize seizure activity, especially if the presentation is complex or confusing.

The primary aims of the treatment of generalized tonic-clonic seizures (GTCS) are to diminish the risk of seizure recurrence, side effects, and to maximize overall quality of life. Most patients with GTCS respond well to medical treatment alone, although some patients may require both medical and non-medical treatments.

• Antiepileptic Drugs (AEDs):  Drugs are the first-line treatment of GTCS. Commonly prescribed AEDs include:
  • Valproic acid (Depakote)
  • Levetiracetam (Keppra)
  • Lamotrigine (Lamictal)
  • Topiramate (Topamax)
  • Carbamazepine (Tegretol)

The selection of drug is based on considerations related to the patient, such as factors described above (i.e. age, sex, side effect profile of drug, other medical concerns, pregnancy status, etc.)

Patients may need regular blood tests to ensure that drug concentrations and liver functions are within the normal range. Patients also need to adhere to their medication for effective seizure control.

• Lifestyle Modifications: Patients should also consider making lifestyle changes, such as:
  • Time for sleep (7–8 hours each night)
  • Avoiding alcohol and recreational drugs
  • Reducing stress (e.g. relaxation, counselling and/or therapy)
  • Staying well hydrated
  • Keeping a seizure diary to help identify trends and possible triggers for seizures.
• Safety Precautions: In order to decrease the chance of injury from seizure:
  • Do not swim or bathe alone.
  • Add safety padding to any furniture with sharp edges.
  • Do not drive unless you have been seizure-free for an appropriate period of time (as established by local laws).
  • Wear a bracelet indicating you have epilepsy in case of an emergency.
• Surgery Options: If seizures are drug-resistant (not manageable with medications), the following options may be available: 
  • Vagus Nerve Stimulation (VNS): A device is implanted in the chest that sends mild electrical pulses through the vagus nerve to the brain. Medication is still needed, but it is likely that the dosages used will be lower.
  • Responsive Neurostimulation: A device is implanted into the brain that finds abnormal brain activity and delivers electrical stimulation to that location in order to prevent a seizure from occurring.
  • Epilepsy Surgery: Generally, this is done with focal seizures. However, for a GTCS that starts in one part of the brain and there is a safe way to remove it, surgery may be available.
• Dietary Treatments:
  • A high fat, low-carbohydrate diet that has been shown to be effective, especially in children with drug-resistant epilepsy. 
  • Low-glycemic index diets may also be beneficial for some adults with epilepsy.
  • Dietary treatments should be undertaken under the care of a physician.
• Psychosocial Support:  Epilepsy may have effects on emotional and social aspects of life. Counseling or psychotherapy may help when feelings of anxiety, depression, or stigma become a barrier. Support groups can assist patients and their families, and educational resources to increase understanding and improve knowledge advocacy.
• Emergency Seizure Management: Seizures that go longer than 5 minutes or a person is in status epilepticus are treated with intravenous (IV) medications such as lorazepam or diazepam to stop the seizure, usually in a hospital settings, or prescribed rescue medication administered at home.

Generalized tonic-clonic seizures (GTCS) are a major neurological disorder with significant physical, emotional, and social consequences. They are distressing, but can throughout the proper management, treatment, changes in lifestyle, and the support of family and friends; be controlled.

Understanding what causes the disorder, recognizing symptoms and knowing the medical and non-medical treatments available can allow the patient and caregivers to manage GTCS. Early diagnosis, follow-up care and safety measures will help to minimize risk exposure and lessen the impact of the disorder on quality of life.

For many people, epilepsy may be a life-long diagnosis, but it does not humanize the individual, nor impede the success of the individual as a member of society. With realistic modern treatments and engaging with the appropriate community support, people will be able to lead busy, productive lives with GTCS. If you, or someone who you care for, thinks that they may be experiencing tonic-clonic seizures, see a doctor as soon as possible. Quick recognition and proper treatment are important to minimize the risk of injury associated with seizures, and in rare instances the risk of life-threatening complications.

• Cleveland Clinic. (2023). Tonic‑Clonic (Grand Mal) Seizure: Symptoms & Treatment. Cleveland Clinic. 
• Medicine Editorial Board. (2022). Generalized Tonic‑Clonic Seizures. Medscape.
• Health.com. (2022). How Is Epilepsy Treated? Health.com.
• Mayo Clinic Staff. (2025a, February 1). Tonic‑clonic (grand mal) seizure – Symptoms & causes. Mayo Clinic. 
• Mayo Clinic Staff. (2025b, February 1). Tonic‑clonic (grand mal) seizure – Diagnosis & treatment. Mayo Clinic. 
• Wikipedia contributors. (2025, June). Causes of seizures. Wikipedia, The Free Encyclopedia. Retrieved June 15, 2025, 
• Corbett, F., & Neurology Consortium. (2021). Epilepsy. Wikipedia, The Free Encyclopedia. Retrieved June 15, 2025