Tests
1st tests to order
anticonvulsant drug blood level
Test
In patients with known epilepsy, poor adherence is the single most common cause of SE.[29]
Result
may be subtherapeutic or absent
toxicology screen
Test
Toxicology should be performed in all cases to unveil any substance misuse/overdose that can lead to seizures and SE.[39]
Result
may be positive for alcohol or potentially epileptogenic substance
comprehensive metabolic panel
Test
Severe electrolyte imbalance, hypoglycemia, and hyperglycemia are treatable and reversible causes of seizures and SE.[32]
Result
may show abnormal glucose and/or other electrolyte abnormalities
CBC
Test
Abnormal CBC results may shed light on the cause of SE. For example, low platelets may indicate intracranial hemorrhage, or elevated white cells may indicate infection as the cause.[32]
Result
may show abnormal levels of red or white cells and platelets
ECG
Test
Arrhythmias or cardiac ischemia may be the result of prolonged SE (and, in rare cases, its cause), and the high risk of these conditions may be under-recognized.[14] Early treatment of these potential complications is of high priority; therefore, serial or continuous ECG monitoring is indicated. Widened QRS complex may suggest overdose of prescribed anti-epilepsy medications including carbamazepine.[14]
Result
may show abnormal heart rhythm or evidence of cardiac ischemia
electroencephalography (EEG)
Test
EEG will have a higher yield when evaluating for nonconvulsive SE and when monitoring response to treatment when patient is rendered iatrogenically comatose.
The presence of an ictal discharge will confirm the diagnosis of persistent subtle generalized SE.
In absence SE, continuous spike-and-wave discharges are usually present, whereas in focal SE with impaired awareness, rhythmic or semirhythmic focal discharges are typically present.
In nonepileptic seizures, the EEG is normal during the attacks. Excessive muscle and movement artifacts are typically seen.
Result
intermittent or continuous focal or generalized ictal discharges
Tests to consider
ABG
Test
Metabolic disturbances (acidosis or alkalosis) may be a complication of SE.[32]
Early recognition and treatment of these conditions is of high importance.
Result
may show abnormal values in the presence of acidosis or alkalosis
CT head
Test
Compared with MRI, CT is faster and easier to do in the emergency room to rule out structural lesions.
Result
may show hemorrhage, evidence of ischemic strokes, edema and tumor, hydrocephalus
lumbar puncture
Test
Should be performed when there is suspicion of encephalitis or meningitis, after a CT scan of the head.[39]
Result
may show high WBC count, high protein, and/or low glucose in the presence of infection
MRI head
Test
Not usually indicated in the acute setting. Serial scans may demonstrate changes consistent with Rasmussen encephalitis in patients (usually children) with simple partial seizures associated with progressive, permanent neurologic disease.
Result
may show hemorrhage, evidence of ischemic strokes, edema, and tumor; hydrocephalus; serial scans showing spread of signal changes and atrophy within the affected hemispheres if Rasmussen encephalitis suspected
continuous EEG (cEEG)
Test
cEEG is recommended by the American Clinical Neurophysiology Society (ACNS) to exclude possible nonconvulsive SE after clinical seizures.[35] The ACNS recommends cEEG for a minimum of 24 hours in critically sick patients with: persistent abnormal mental status following generalized convulsive SE or other clinically evident seizures; acute supratentorial brain injury with altered mental status; fluctuating mental status or unexplained alteration of mental status without known acute brain injury; routine EEG that shows periodic discharges (generalized, lateralized, or bilateral independent) or lateralized rhythmic delta activity; requirement for pharmacologic paralysis (e.g., therapeutic hypothermia protocols, extracorporeal membrane oxygenation), and risk for seizure; clinical paroxysmal events suspected to be seizures, to determine if they are ictal or nonictal.[35] If resources do not permit cEEG monitoring, frequent serial EEGs should be obtained to guide therapy, and physicians may consider transferring the patient to a facility with cEEG capabilities.
Result
intermittent or continuous focal or generalized ictal discharges
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