Approach to Seizures

Primer

Seizures are sudden, uncontrolled electrical disturbances in the brain. The presentation can vary from uncontrolled jerking movement (tonic-clonic seizures) to something as subtle as a momentary loss of awareness (absence seizure).

Epilepsy

An epileptic seizure is a transient occurrence of signs and symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Epilepsy is a disorder of the brain characterized by an enduring predisposition to generate epileptic seizures. Epilepsy is not a single disease, but rather a collection of disorders that have in common the epileptic seizure event.

What's the difference between seizures and epilepsy?

Although the two terms are often used simultaneously, they do not mean the same thing:
  • Seizure = a single event
  • Epilepsy = 2 or more unprovoked seizures
    • Seizures caused by metabolic (e.g. - hypoglycemia, hyponatremia), toxic (e.g. - uremia), or substance use (alcohol withdrawal seizures) does not count towards a diagnosis of epilepsy

Triggers and Risk Factors

Triggers for seizures include:

  • Sleep deprivation
  • EtOH/substance abuse
  • Stress
  • Infection
  • Hypoglycemia
  • Hyponatremia
  • Premenstrual period
  • Head injury

Risk factors include:

  • Family history of seizures/epilepsy
  • Personal history of febrile seizures
  • Personal history of CNS infection (meningitis/encephalitis)
  • Head trauma with post-concussive symptoms or loss of consciousness
  • Perinatal hypoxia/head trauma
  • Structural brain lesions
  • Personal history of developmental delay
  • Co-morbid conditions: alcoholism or renal failure
  • Diabetes (and insulin use, which increases risk for hypoglycemic seizures)

Status Epilepticus

Status epilepticus is defined as when there is more than 5 minutes of a continuous seizure OR there are 2 or more discrete seizures in which there is incomplete recovery of consciousness. Lorazepam is the first line in-hospital treatment for status epilepticus.

Diagnostic Criteria

A pratical definition of epilepsy is if the patient meets 1 of the following:[1]

  1. At least 2 unprovoked (or reflex) seizures occurring greater than 24 hours apart
  2. 1 unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after 2 unprovoked seizures, occurring over the next 10 years
  3. Diagnosis of an epilepsy syndrome

Types

Seizures can either be generalized or focal (partial). Any focal seizure can evolve into a bilateral convulsive seizure. A focal seizure usually evolves into a bilateral seizure when the head begins to turn to the direction contralateral to the hemisphere of seizure origin.

Focal

Focal seizures are:

  • Limited to one hemisphere
  • More discretely localized
  • May spread to the other hemisphere, and becomes a generalized epileptic seizure
  • The patient may have partial or complete amnesia
  • The seizures may involve motor activity/automatisms, which are coordinated, repetitive actions that seem purposeful, but are no voluntary
  • Lip smacking, licking, fumbling with hands (tardive dyskinesia) can be seen
  • These can begin as focal seizures without impairment of consciousness

Focal seizures can be further classified into:

  1. Impairment of consciousness (also known as complex partial seizures or focal dyscognitive)
  2. No impairment of consciousness (also known as simple partial seizures)
    • Have auras
    • There is intact awareness and they are aware of seizure occuring
    • Have observable motor (focal motor seizure) or autonomic features (autonomic seizure, such as increased heart rate, sweating)

Generalized

Generalized seizures involve both cerebral hemispheres. There are 6 types of generalized epileptic seizures:

  1. Tonic = sustained contraction
  2. Atonic = complete loss of sustained contraction (drop seizures)
  3. Clonic = contracting/relaxing
  4. Myoclonic = brief contraction
  5. Absence = nothing happening, blank stare (note: it is rare for an absence seizure to last longer than 15 seconds[2])
  6. Tonic-Clonic = sustained contraction plus contracting/relaxing

History

Taking a history for seizures is important, as this will help you determine the etiology and type of seizure.

  • How did the patient feel after the seizure? How long did it take for the patient to get back to baseline condition? Was there confusion (post-ictal confusion?)
  • Was any there any warning noted before the seizure? If so, what kind of warning occurred?
  • What was the patient doing during the seizure?
  • Was the patient able to relate to the environment during the seizure and/or does the patient have recollection of the seizure?
  • How long did the seizure last?
  • How frequently do the seizures occur?
  • Is anything known to precipitate the seizures?
  • Has the patient shown any response to therapy for the seizures?

Investigations

  • CBC, LFTS, electrolytes (hyponatremia can lead to seizures), extended lytes (Hypocalcemia, hypercalcemia, and hypomagnesemia can lead to seizures[3])
  • Albumin (specific for starting highly protein bound drugs, phenytoin, valproic acid)
  • Substance screen
  • CT Head (looking for masses)
  • MRI (looking for medial temporal sclerosis, MRI > CT in showing lesions associated with epilepsy)
  • EEG (only abnormal in 50% of cases, so it neither confirms nor denies diagnosis of epilepsy)

Neuroimaging

Mesial temporal sclerosis

Mesial temporal sclerosis (or hippocampal sclerosis) is scarring in the inner portions of the temporal lobe, especially in the CA1 and CA2 regions of the hippocampus. It is the most common pathological finding in patients with intractable temporal lobe epilepsy (TLE).[4]

Focal cortical dysplasias (FCD)

Focal cortical dysplasias (FCD) are a heterogeneous group of disorders of cortical formation, which are one of the most common causes of epilepsy and can be associated with hippocampal sclerosis and cortical glioneuronal neoplasms.[5]

Treatment

Safety

Ensure the ABCs are monitored closely and that supplemental oxygen is available. Make sure the patient is not at risk of falling, and remove restrictive clothing. Do not place anything in the patient’s mouth unless it is a bite block or an oropharyngeal airway (OPA) to protect the tongue.

Benzodiazepines

First-line treatment is with benzodiazepines IV until seizures are controlled:

  • Lorazepam 2mg q2-5minutes PRN, or
  • Midazolam 2mg q2-5minutes PRN, or
  • Diazepam 5mg q2-5minutes PRN

If there is difficulty with IV access, lorazepam, midazolam, and diazepam can all be given IM. PR delivery can also be considered. PO benzodiazepines should not be used unless they are alert and have a normal mental status.

Seizure Prophylaxis

  • Load with phenytoin 1000mg (standard), but you should do a weight-based dosing of 20mg/kg
    • Phenytoin overdose results in horizontal nystagmus on physical exam
  • Then phenytoin 300mg PO daily, measuring a dilantin level several days later
  • Valproic Acid (VPA) / Divalproex (DVP) (Epival) is also a broad spectrum agent and first line for generalized epilepsy syndromes. It is teratogenic though, and newer agents like lamotrigine, topiramate, and levetiracetam (e.g. - 500mg PO BID) are more appropriate for women of child-bearing age.

Status Epilepticus

Status Epilepticus Treatment

Medications Management
• Lorazepam 2-4mg IV push
• If ongoing seizure activity after 5 minutes, repeat x1, give phenytoin 20mg/kg, give simultaneously 		• ABCs
• Pin prick blood glucose
• Thiamine 100mg IM/IV prior to administrations of dextrose
• Give 1 amp D50W if glucose low or unknown
• Cardiac monitor
• Obtain bloodwork
• If ongoing seizure activity, consult ICU for intubation and infusion of either: midazolam OR propofol • Give bolus medications until seizure stops
• For breakthrough seizures, re-bolus and increase rate of infusions
• Begin continuous EEG monitoring if IV infusion used or patient does not wake up rapidly with resolution of convulsions
• For ongoing seizure activity, add additional agents via IV or NG tube, e.g. - valproate, levetiracetam, phenobarbital
• Phenytoin (Dilantin) is given as a secondary drug to prevent recurrent seizures, because of lorazepam's short half life 		• Obtain neuroimaging when convulsions stop
• Consider lumbar puncture/antibiotics if there is a clinical suspicion of infection

References

1) Fisher, R. S., Acevedo, C., Arzimanoglou, A., Bogacz, A., Cross, J. H., Elger, C. E., ... & Hesdorffer, D. C. (2014). ILAE official report: a practical clinical definition of epilepsy. Epilepsia, 55(4), 475-482.
2) Posner E. (2013). Absence seizures in children. BMJ clinical evidence, 2013, 0317.
3) Nardone, R., Brigo, F., & Trinka, E. (2016). Acute symptomatic seizures caused by electrolyte disturbances. Journal of Clinical Neurology, 12(1), 21-33.
4) Spano, V. R., & Mikulis, D. J. (2011). Mesial temporal sclerosis in epilepsy. CMAJ, 183(15), E1151-E1151.
5) https://pubmed.ncbi.nlm.nih.gov/25296548/