06. Seizure

Resident Editor: Jesse Fitzpatrick, MD

Faculty Editor: Paul Garcia, MD

BOTTOM LINE

✔ All patients with new seizures should get a basic laboratory workup, head imaging, and (if these are unrevealing) EEG.

✔ Initiation of an AED after a first unprovoked seizure provides only modest benefit, reducing the short-term, but not long-term risk of recurrence; the decision should incorporate patient preference.

✔ Neurology referral is required in cases of recurrent seizure, if an AED is started, or if an underlying neurologic etiology is found.

Background

  • Incidence 8-10% of the population over a lifetime.1
  • 1 in 6 patients who present with a single seizure will have an identifiable cause.2
  • Risk factors include stroke, meningitis/encephalitis, electrolyte abnormalities, hypoglycemia, central nervous system tumors, and traumatic brain injury.

Classification

  • Seizures were reclassified in 2017 into three main categories by location of origin: focal onset, generalized onset, and unknown onset. Seizures are further classified by motor vs non-motor, aware vs non-aware, and whether a focal seizure becomes bilateral. A comprehensive description of the new classification system can be found at: https://www.epilepsy.com/article/2016/12/2017-revised-classification-seizures
  • Status epilepticus is defined as a continuous seizure for >5 minutes or multiple seizures in that timeframe without a return to baseline.

Differential Diagnosis

  • Stroke or transient ischemic attack
  • Syncope
  • Migraine
  • Psychogenic non-epileptic seizures
  • Narcolepsy with cataplexy
  • Panic attack

Evaluation

  • History: Detailed seizure history (events prior, onset, focality, duration, loss of awareness, post-ictal state), review predisposing conditions (head trauma, drugs/etoh, stroke).
  • Exam: ABCs, vital signs, full neurologic exam. Look for evidence of injury during a seizure.
  • Laboratory: There is little data to support routine laboratory workup, however, it is reasonable to obtain BMP with Ca/Mg, glucose, CBC, +/- toxicology, +/- pregnancy test. 
  • Other testing:2-4
    • MRI (preferred) or CT should be obtained (yield 10%). Immediate imaging is indicated when serious structural brain legions are suspected and can be considered in patients with partial-onset seizures or those >40 years old. 
    • Unless initial evaluation reveals a cause, an EEG should be obtained in the first 48 hours (yield 29%,) but can be done as an outpatient (unless there is a concern for status epilepticus). 
    • Lumbar puncture need not be routinely performed but is reasonable in the febrile patient if meningitis is suspected, or in an immunocompromised patient. 

Treatment

  • Acute management: Usually self-limited, initial goals are to assess ABCs, get a POC glucose, and create a safe space. Do not insert anything into the oral cavity. In cases of status epilepticus, initiate the following management steps.
    • Ativan 2mg IV, can repeat q2min X1-2 doses if no response. If no IV access can give midazolam 10mg IM/buccal/nasal or rectal diazpam (diastat) 10mg.  
    • Fosphenytoin 20mg/kg at 150mg/min in saline or dextrose. 
    • Call neurology and see management of “status epilepticus” in the hospitalist handbook. 
  • Initiation of an AED:
    • AAN guidelines recommend shared decision-making regarding starting an AED after a first unprovoked seizure.3
    • AEDs reduce recurrent seizure risk in the first 2 years (35% risk reduction) after a first unprovoked seizure but do not change recurrence rates after 3 years.3
    • A delay in initiating AEDs after a first unprovoked seizure does not change long-term remission rates.3
    • In nearly all cases, AEDs should be initiated after a recurrent seizure.

Referral

It is reasonable to seek expert consultation after a first unprovoked seizure. Expert consultation should be sought after recurrent seizures, the first seizure when an uncorrectable provoking factor is identified, or if an AED is initiated. 

Reporting

All conditions characterized by the unexpected loss of consciousness in a patient aged 14 or older must be reported to the Department of Public Health utilizing a Confidential Morbidity Report. Typically, driving is not allowed for 3 months following a seizure unless there is a reason to be confident that there will not be a recurrence. 

Prognosis

  • The risk for recurrent seizure after a first unprovoked seizure is highest in the first 2 years and ranges from 21-45%.3
  • The risk of recurrence is higher in patients with a positive EEG, abnormal imaging, or nocturnal seizure. 3

*The preceding information applies only to adults and should not be applied to children.

References

Hauser WA, Annegers JF, Rocca WA. Descriptive epidemiology of epilepsy: contributions of population-based studies from Rochester, Minnesota. Mayo Clin Proc 1996;71:576-586.

Adams SM, Knowles PD. Evaluation of a first seizure. Am Fam Physician 2007;75:1342-1347.

Krumholz A, Shinnar S, French J, Gronseth G, Wiebe S. Evidence-based guideline: Management of an unprovoked first seizure in adults: Report of the Guideline Development Subcommittee of the American Academy of Neurology and the American Epilepsy Society. Neurology 2015;85:1526-1527.

Krumholz A, Wiebe S, Gronseth G, Shinnar S, Levisohn P, Ting T, Hopp J, Shafer P, Morris H, Seiden L, Barkley G, French J, Quality Standards Subcommittee of the American Academy of N, American Epilepsy S. Practice Parameter: evaluating an apparent unprovoked first seizure in adults (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology and the American Epilepsy Society. Neurology 2007;69:1996-2007.