Seizures

Department of the Navy
Bureau of Medicine and Surgery

True seizures, also called epileptic seizures, are caused by the sudden, uncontrolled discharge of a group of neurons in the cerebral cortex. These may affect the entire cortex, causing a generalized seizure, or may begin focally or regionally, and cause a partial seizure. An epileptic seizure can be triggered by a single event, or may be due to a chronic tendency (diathesis) to cause seizures. Epilepsy is a condition with recurring epileptic seizures. The following three cardinal characteristics set seizures apart from other episodic behaviors or sudden losses of function, regardless of the cause or type of seizure:

• Sudden or abrupt onset.

• Stereotype.

• Irrelevance to the environment or situation.

Generalized versus Partial (focal)

Seizures that begin focally are called partial seizures. A simple partial seizure does not affect consciousness. Complex partial seizures originate in cortical areas that control thoughts, images, or emotions without external signs of somatic involvement.

• Some partial seizures may spread from the initial focal onset over several seconds, and this may appear behaviorally to be a gradual onset, but the initial focal features are sudden, and even the spread takes seconds, not a long time.

• Complex partial seizures may begin with unusual thoughts, autonomic symptoms, or repetitive behaviors. The same sequence is followed exactly with every attack. Dreamy or fugue-like behaviors that respond to the environment, interactive conversations, or directed violence are never seizures.

• The patient will recall an aura or prodrome as the first manifestation of an actual seizure, before the seizure progresses to a more intense stage. Since every partial seizure tries to become a convulsion, it is critical to remember that an aura is a seizure. If auras continue, the seizures are not completely controlled.

• Generalized seizures involve the entire cortex. These may be secondarily generalized, by spreading from a focal onset, or may be primarily generalized, involving the entire cortex from the outset. One special type of generalized seizure, called absence seizure, causes very brief staring spells. These spells last for only a few seconds. Since they are generalized cerebral seizures, all consciousness is suspended during the seizure. Absence seizures particularly affect children between the ages of 3 and 12, and they may occur dozens to hundreds of times a day.

• The most commonly encountered seizure in a military population is the generalized tonic clonic seizure. A tonic seizure first has a generalized tonic phase lasting 1 to 5 seconds, followed by a series of accelerating generalized symmetrical clonic movements. (Note: there is no such thing as a "tonic-clonic movement." There is a tonic posture, and then there are clonic movements.) Observers may not detect a seizure until the clonic phase is underway. However, the sequence is important if it can be recognized and documented.

• Syncope may conclude with a few clonic jerks, but does not include a tonic phase. Hysterical seizures may often have very convincing jerking movements, but usually omit the tonic phase, which is less well known.

Treatment and General Principles

Treatment for seizures has become more complicated as a large number of seizure medications have become available, and have relatively specific uses for particular kinds of seizures. This section will not give detailed guidance on the diagnosis and treatment of seizures because of the many varied considerations involved. However, general points will be covered to clarify diagnostic and treatment issues. Referral to a neurologist must be obtained for the complete diagnostic work-up and initiation of therapy. Here are some general principles the GMO should keep in mind involving the diagnosis and treatment of seizures:

• Seizures are a symptom. Find out the cause of the seizures.

• Partial seizures suggest focal lesions.

• An EEG clarifies the physiologic features of the seizure and may clarify focal characteristics, but cannot show anatomic lesions.

• A CT or MRI demonstrate anatomy and many types of lesions, but not physiology

• Most seizures can be controlled with a single drug.

• The most common reasons for seizures to occur despite treatment are either not using the most effective drug for the specific seizure or using too low a dose.

• The most effective drugs for absence seizures are valproate or ethosuximide.

• The most effective drugs for partial seizures and generalized tonic-clonic seizures are carbamazepine, phenytoin, and valproate.

• Phenobarbital and primidone are not first line drugs for any form of seizure.

• Plasma drug levels are useful for monitoring compliance and fluctuations in the patient's metabolism of the drug. Over time, induction or drug-drug interactions may alter drug levels in circulation. However, drug levels are only adjuncts and guidelines in managing therapy, they are not targets that can predict drug efficacy or side effects.

Most first seizures that occur in a military population will be generalized tonic-clonic convulsions. The first step is to protect the patient from injury, and not to make the situation worse. After placing the patient on the deck or floor, turn him or her on the side, and place something soft under the head. The jaws will usually be clenched. Do not place anything hard, like a tongue blade (even if padded) between the teeth. Ensure the airway, breathing, and circulation (ABC’s) are maintained as well as the safety of the patient.

Next, try to make a diagnosis. Don't be too quick to treat. A single seizure may be caused by alcohol withdrawal, some toxicants, or neurological disease (see causes). It is important to examine the patient as soon as possible after the seizure, for signs of focal deficit or evidence of associated disease. If the seizure is due to alcohol withdrawal, it may be wise to treat the patient with a benzodiazepine drug. Do not initiate antiseizure medications for alcohol withdrawal. If the seizure has stopped and the patient is within an hour of a diagnostic center, do not initiate medication. Let the treatment be initiated by the team who will be treating him or her.

Causes of Single or Transient Seizure

• Alcohol withdrawal

• Drug reaction

• Chemical toxins: hydrocarbons, pesticides, fluorocarbons, etc.

• Head trauma

• Infection: encephalitis, meningitis, malaria

• Cerebral vasculitis

• Eclampsia

• Subarachnoid hemorrhage

• Parenchymal brain hemorrhage

• Embolic cerebral infarction (not common)

Syncope should be distinguished from seizures. Hypotension, hypovolemia, cardiac arrhythmia, sudden increase in vagal tone, and sometimes extreme startling can cause syncope. The commonest cause of syncope, in a military setting is prolonged standing, especially in the heat. Syncope is usually preceded by a sense of lightheadedness or weakness. The fall from syncope is a swooning collapse, whereas with a generalized tonic-clonic convulsion, the patient is usually rigid and falls as though propelled. After the syncopal episode and the victim falls, perfusion is usually rapidly restored and the patient becomes alert fairly rapidly, although he may feel weak for minutes. After a seizure, by contrast, there is a post-ictal period of stupor lasting many minutes to nearly an hour. A patient usually has a headache after a seizure, rare after syncope. Biting and injury to the tongue or lips is common with a seizure, rare in syncope. A patient with a full bladder may urinate during either kind of spell, but it is a bit more common with a seizure.

Continuous clinical or electrical seizures’ lasting more than 30 minutes without an intervening lucid interval is called status epilepticus. This is a neurological emergency. The seizures must be terminated as rapidly as possible to prevent permanent brain damage as well as death from hypoxia, acidosis, rhabdomyolysis, and secondary renal damage. This requires a team approach.

• The first step is aggressive airway support to include intubation if necessary. Pulse oximetry, cardiac monitor, and intravenous access are also necessary. Check a finger stick blood glucose. IV infusion of a benzodiazepine agent such a diazepam or lorazepam in doses sufficient to arrest the convulsion are required, up to 20 mg of diazepam or 8 mg of lorazepam over 5 to 10 minutes. This will almost always stop the convulsion. If it does not, then an anesthesia provider should be requested to induce general anesthesia. The patient will be severely acidotic at this time, for which good ventilation and supplemental oxygen are the main treatments. While one member of the treating team takes blood samples for electrolytes, blood count, glucose, calcium, a toxicology screen, and blood levels of the patient's antiseizure medication (if applicable), another should push 100 mg of thiamine intravenously with an ampule of 50 percent glucose. This should be followed by an ampule of naloxone.

• A member of the team should vigorously seek out the patient's history to identify antecedent events - especially a history of seizures. The most common cause of status epilepticus in the U.S. and Europe is the discontinuation of medication in a person with epilepsy.

• The effects of the initial dose of benzodiazepine will usually wear off after 20 minutes, so a longer acting agent will be required, unless an underlying metabolic cause for the seizure is identified. If the history does not disclose a treatable cause for the seizures, or if the patient usually takes phenytoin, then infuse phenytoin 15-18 mg/kg at a rate of 50 mg/min. Avoid administering phenytoin along with glucose containing solutions since phenytoin precipitates within the tubing. If seizures recur or continue, an additional 7 mg/kg of phenytoin should be given. If seizures still recur or continue, Phenobarbital should be infused at a dose of 20 mg/kg. It is exceedingly rare for the seizure to continue after all this, but if it does, general anesthesia is required.

• If at this point, no cause has been identified, then an imaging study to identify cerebral hemorrhage or mass should be done, rapidly followed by lumbar puncture to identify meningitis or encephalitis.

• Once stabilized, the patient should be transferred to a tertiary care facility for ICU admission.