Seizures After Anesthesia
Seizures After Anesthesia Can Have Many Causes
Seizure as a Complication of Anesthesia
Seizures after anesthesia are rare, but they are recognized as a potential complication.
Anesthetic medications act on the central nervous system, so it is not surprising that various medicines influence the seizure threshold. Some of the medications used during anesthesia lower the threshold, making them more likely. Others raise the threshold, making fits afterward less likely. Further, there can be direct toxic effects of some medications, such as local anesthetics, that cause seizures when absorbed in large amounts into the bloodstream.
Who Is at Risk?
When seizures do occur in the postoperative period, they happen most often to those who already have epilepsy or other related disorders.
They are most common in people whose seizures are not well controlled before surgery and in patients who are undergoing brain surgery.
Seizure after surgery and anesthesia can rarely occur as random events. An occurrence in a postoperative patient who doesn’t already have a disorder should prompt a search for structural or chemical brain abnormalities.
Prevention in Epileptics
If you have epilepsy and your surgery is elective, you should work closely with your neurologist to optimize your anti-epilepsy drugs prior to surgery. Good control with stable doses of medication will decrease the risk of seizures after surgery.
It will also be important to have a meeting ahead of time with an anesthesiologist or nurse working in a pre-op clinic. Make sure they know about your epilepsy and current medications. The standard pre-op instructions may say not to take any medication, but you should specifically ask about seizure medications, especially if you are prone to them if you miss a dose of medicine.
Also, if you have motion sickness or known issues with nausea and vomiting after anesthesia or with pain medications, ask for a prescription for an anti-nausea medicine with your pain meds. If you can’t keep your drugs down, you are more likely to have an episode in the first few days after surgery.
Pre-Existing Risk Factors
- Pre-existing epilepsy or seizure disorder, especially if poorly controlled
- Lengthy surgery or surgery that lasts longer than the effectiveness of the last dose of medication in epileptics
- Pre-existing brain abnormality such as a tumor, aneurysm or scarring
- Alcoholism and alcohol withdrawal
- Illicit drug use
- Local anesthesia in large doses
- Certain anesthetics in combination with any of the above
Causes in Non-Epileptics
When a seizure occurs after surgery in someone who hasn’t had previous history, several reasons would initially be suspected.
- Alcohol withdrawal may be the most common reason.
- Chemical or electrolyte abnormalities can be a rare cause.
- A previously unknown or undiagnosed brain tumor or other problem may exist.
- Seizure is a known complication of an overdose of local anesthetics like lidocaine.
Further workup will depend on the suspected reason.
If alcohol-withdrawal is suspected, the patient will usually be admitted to the ICU and medications ordered to counteract the dangerous effects of withdrawal.
Involvement of a neurologist is recommended in cases where the cause is not obvious.
Anesthesia Meds That Probably Make Seizure More Likely
Anesthesia Meds That Probably Make Seizure Less Likely
Undetermined or Varies by Situation
Other Inhaled Agents
From the Operating Room...
Of note, in my residency, I had a young man (with no history of seizure) experience a grand mal seizure as he woke from general anesthesia for a testicular tumor excision. Blood work did not show any abnormality, but since his testicular biopsy was positive for cancer, we ordered a CT scan of the brain. He was found to have a lesion on his brain, probably unrelated to his cancer, that was almost certainly the seizure focus. He had a past history of methamphetamine drug abuse, but his drug screen after surgery was negative for stimulants. He did on further questioning report previous trauma to the head which could have accounted for the lesion seen on imaging. We published this experience as a case report in a leading anesthesia journal, since the anesthesia gas we used was still fairly new and had unknown potential to lower the seizure threshold.
- Hilty, CA and Drummond, JC; Seizure-like Activity on Emergence from Sevoflurane Anesthesia; Anesthesiology: Nov 2000; 93(5); 1357-9.
The Bottom Line
- Seizures after surgery are sufficiently rare that you should only really consider them a possibility if you have a pre-existing condition that puts you at higher risk.
- If you drink alcohol in excessive amounts or have had signs and symptoms of withdrawal in the past, make sure the anesthesiologist and surgeon are aware of this.
- If you are an epileptic, make sure your neurologist is aware that you have scheduled surgery. Ask if you need a blood test to check the levels of your medicine. Find out when you should take your medication before and after surgery and discuss this with the anesthesiologist before undergoing surgery.
- If you use drugs, be honest. We can deal with many situations, but if we have to play a guessing game, we are less likely to be successful.
- Discuss all medication and other medical conditions with the anesthesiologist, especially if you take medication that is known to affect your blood chemistry and electrolytes (diuretics, for example).