A seizure is a sudden, uncontrolled burst of electrical activity in the brain that can cause changes in thinking, movement, consciousness, behavior, or feelings. While uncommon after surgery, understanding their potential origins is important. Seizures range from subtle changes in awareness to generalized convulsions with loss of consciousness. Most seizures last less than two minutes, though some can be prolonged and require immediate medical attention.
Immediate Surgical Influences
Certain aspects of the surgical procedure or the body’s immediate physiological responses can directly contribute to seizures. Some anesthetic agents, such as isoflurane, sevoflurane, and ketamine, can lower the seizure threshold in susceptible individuals, potentially triggering seizures during induction or emergence from anesthesia. Rapid changes in their concentration in the brain can also play a role.
Fluid shifts and surgical stress can lead to electrolyte imbalances, which trigger seizures. For instance, low sodium levels (hyponatremia) can result from excessive intravenous fluid administration or the body’s stress response. Imbalances in calcium (hypocalcemia) and magnesium (hypomagnesemia) can also disrupt normal electrical signaling, causing seizures.
In neurosurgery, direct manipulation or irritation of brain tissue during the procedure can cause seizures. This is relevant in surgeries involving brain tumors or other intracranial lesions. The acute stress response to surgery, characterized by the release of hormones like cortisol and inflammatory cytokines, can also impact neurological stability.
Underlying Patient Vulnerabilities
A patient’s pre-existing health conditions or characteristics can increase their risk of seizures after surgery. Individuals with a history of neurological conditions, such as epilepsy, previous strokes, or brain tumors, are more susceptible. For example, patients with epilepsy may experience breakthrough seizures if their anti-seizure medication regimen is altered during the perioperative period due to factors like being unable to eat or drink before surgery.
Systemic medical conditions can predispose individuals to seizures. Uncontrolled diabetes, kidney failure, or severe liver disease can heighten seizure risk. Infections, even those not directly affecting the brain, can trigger seizures in vulnerable patients.
The patient’s medication history is important. Certain medications, including some antidepressants like bupropion and tricyclic antidepressants, or antipsychotics such as clozapine and chlorpromazine, can lower the seizure threshold. Abrupt withdrawal of anti-seizure medications before or after surgery can lead to seizure recurrence.
Age plays a role in seizure vulnerability. Both very young and very old patients may have different physiological responses and underlying conditions that increase their risk of seizures following surgery. For instance, epilepsy onset is more common in children and older adults.
Post-Operative Complications
New issues arising after surgery can lead to seizures, and prompt recognition and treatment of these complications are important. New blood clots or bleeding in the brain, known as stroke or ischemia, can occur post-operatively and cause seizures. Hemorrhagic strokes, caused by a burst artery, are associated with a higher incidence of seizures compared to ischemic strokes.
Post-surgical infections, especially those affecting the central nervous system like meningitis or encephalitis, trigger seizures. These infections cause inflammation and can disrupt normal brain activity.
An accumulation of blood in or around the surgical site, known as a hematoma (e.g., epidural or subdural hematoma), can put pressure on the brain and directly cause seizures. Such hematomas can lead to abnormal electrical activity due to irritation of brain tissue. Brain swelling, or edema, is another complication where inflammation and fluid buildup increase intracranial pressure, potentially resulting in seizures.
Medication-related issues post-surgery can induce seizures. This includes adverse reactions to newly prescribed post-operative medications. Withdrawal from substances like alcohol or benzodiazepines, if discontinued abruptly before or after surgery, can precipitate severe withdrawal seizures.
Insufficient oxygen supply to the brain, or hypoxia/anoxia, is a post-operative complication that can lead to seizures. Brain cells are sensitive to oxygen deprivation, and prolonged lack of oxygen can result in brain damage and seizure activity.