Definition

A transient disturbance of cerebral function due to synchronized neuronal discharge.

Etiology/Risk Factors

• Provoked (systemic process leading to seizures):
  • Metabolic (hypo/hypernatremia, hypo/hyperglycemia, hypomagnesemia, hypocalcemia, hyperammonemia, hyperthyroidism, uremia, hyperthermia)
  • Cerebrovascular (HTN encephalopathy)
  • Systemic infection
  • Toxic (alcohol withdrawal, barbiturate or benzo withdrawal, drugs of abuse [sympathomimetics, PCP])
  • Medication (tramadol, imipenem, theophylline, bupropion, clozapine, etc.)
• Symptomatic (process localized to brain leading to seizures):
  • Acute symptomatic:
    • Cerebrovascular – ischemic stroke, intracranial hemorrhage, hypoxic-ischemic injury, vasculitis, posterior reversible encephalopathy syndrome (PRES)
    • Infection: meningitis/encephalitis, abscess, neurocysticercosis, fungal infections, TB
    • Autoimmune/paraneoplastic (NMDA receptor encephalitis, SLE, Hashimoto’s, etc.)
    • Structural – tumor, metastases
  • Remote symptomatic – prior stroke, TBI, meningitis/encephalitis, etc.
• Epilepsy syndrome: idiopathic or genetic epilepsy
  • Age 10-40 years: idiopathic, trauma, drugs/withdrawal, metabolic
  • Age 40-60 years: tumor, trauma, drugs/withdrawal
  • Age > 60 years: vascular, tumor, subdural, infection

Differential Diagnosis

Syncope; hyperventilation syndrome; movement disorder; tremor; psychogenic nonepileptic seizure, narcolepsy.

Evaluation

• History: important to question both the patient and bystanders, if possible.
  • Patient background: is this the patient’s first seizure, or have they had seizures before? 
  • Seizure characteristics: presence of preceding aura (e.g., déjà vu, olfactory or gustatory hallucinations, feeling of fear, epigastric rising, visual symptoms); appearance and progression of motor symptoms (head turning, eye deviation [left or right], unilateral or bilateral tonic, clonic, or tonic-clonic activity); loss/alteration of consciousness; seizure duration; presence of tongue biting and/or incontinence; presence and duration of post-ictal confusion/lethargy; post-ictal neurological symptoms, if any
  • Risk factors for seizure 
    • History of febrile seizures
    • Traumatic brain injury
    • CNS infections/neoplasms
    • History of malignancy
    • Family history of epilepsy
    • Gestational/developmental complications (young patients)
  • Seizure triggers
    • Sleep deprivation
    • EtOH withdrawal
    • Drugs
    • Systemic infection
    • Menses 
  • In patients with epilepsy, the most common cause for seizures is medication noncompliance or subtherapeutic levels
• Physical:
  • ABCs, vital signs
  • Look for injuries sustained while seizing: tongue lacerations, shoulder dislocation, head trauma. Assess level of consciousness and do a full neuro exam, looking in particular for any focal neurological deficits that could guide your workup. Focal neurological deficits may indicate an underlying brain lesion, or they may reflect post-ictal (“Todd’s”) paralysis, which should resolve within 48 hours (can be longer for elderly patients, especially if several sedating medications are administered). Persistent encephalopathy may reflect recurrent seizures or status epilepticus
• Labs: glucose, chem panel (including Mg/Ca), CBC, LFTs, ammonia, urinalysis, urine tox screen, AED levels (if known epilepsy; phenytoin, valproic acid, carbamazepine and phenobarbital available immediately)
• Imaging: urgent CT for work-up of first-time seizures to evaluate for hemorrhage, mass, abscess followed by MRI (particularly in patients with focal seizure activity)
• Further workup:
  • EEG can often identify interictal (between seizures) epileptiform discharges, even if no seizure occurs during the recording
    • Note that a normal EEG does not rule-out epilepsy 
    • EEG most sensitive if performed <24 hours after seizure
  • LP is useful in patients with recurrent seizures and/or status epilepticus and who are immunocompromised, febrile, not returning to baseline

Management

• Patient is actively seizing:
  • Give O2 by face mask, position patient on side, suction airway if needed. Protect patient from harming self. Do not try to put oral airway, gauze, etc. into mouth (risk of damage to teeth/injury to provider)
  • Give IV thiamine 100mg and 50mL of 50% dextrose
  • If seizures continue > 2-3 minutes, give one of the following to try to abort the seizure: lorazepam 0.1mg/kg IV at a rate of 2 mg/minute (max 4 mg per dose), or midazolam 10 mg IM. Diazepam 0.2 mg/kg PR or IV is an alternative if lorazepam/midazolam not available 
  • If this fails, see section Status Epilepticus for further management
• Once seizure has terminated:
  • Continue investigating for underlying cause(s) of seizure activity, if not yet elucidated
  • Place patient on seizure precautions (padded bedrails prevent injury during seizure)
  • Watch patient for complications of seizure, particularly lactic acidosis and rhabdomyolysis
  • If post-ictal confusion does not begin to clear within hours, consider medication effect or continued non-convulsive seizure
• When to start anti-epileptic drugs (AEDs):
  • Most start AEDs after the patient’s second unprovoked seizure, given the high risk of recurrence (80%)
  • However, it is reasonable to initiate AED therapy after the first seizure if patient has the following risk factors for recurrence:
    • Evidence of structural brain disease on imaging (e.g. mass lesion)
    • Abnormal neurological exam with focal findings, including intellectual developmental disorder
    • Epileptiform abnormalities on EEG
• Selection of an AED: should be based upon the patient’s seizure type (focal vs generalized) and comorbidities, adjusting as needed to optimize the side effect profile. If there is any uncertainty, consult neurology.
• Driving safety: in some states (e.g., California) it is your legal responsibility as the diagnosing physician to report the patient’s condition to the Department of Public Health. They will, in turn, report this to the DMV

Key points

• A careful history and physical are extremely important in elucidating the underlying cause of a seizure and should guide your workup and treatment plan.
• Focal seizure activity should raise concerns for underlying structural disease, and a thorough workup should be performed to rule this out accordingly.
• The decision of whether or not to initiate AED treatment after the first seizure depends on the patient’s individual risk of recurrence. The specific agent chosen depends upon the type of seizure suffered, the patient’s comorbidities, and the side effect profiles of each agent.