As in all other areas of medicine, effective treatment of status epilepticus (SE) is facilitated tremendously by the correct diagnosis! Convulsive SE is rarely a diagnostic difficulty, but nonconvulsive forms, including episodes after generalized seizures, may be difficult to recognize or missed altogether.

Differential diagnosis

Shaking and responding poorly do not always indicate epilepsy. The differential diagnosis of apparent SE includes movement disorders, psychiatric disorders, and other conditions. Treating these conditions as SE may result in significant harm.Table: Differential Diagnosis of SE

Nonepileptic seizures ("pseudoseizures" or "pseudo status") are particularly troublesome. These episodes often occur in patients who also have epileptic seizures. Features that suggest nonepileptic spells include:

• out-of-phase limb movements
• complicated vocalizations
• forced eye closure during the event with resistance to eye opening, eyes are usually open during both partial and tonic-clonic seizures
• tearfulness or sobbing during or after the seizures
• absence of epileptiform features on the EEG during spells and quick return of normal background following termination of the spell (Epileptic seizures cannot be totally excluded because the surface EEG may be unaffected by some epileptic seizures, especially in the frontal lobe

Iatrogenic morbidity is common in these patients, and spells may persist until treatment causes respiratory arrest. The spells often recur. Thorough psychiatric evaluation and treatment are appropriate but not always successful.

History and physical

The patient's history often reveals the cause of a patient's SE. Factors such as trauma, drug overdose, alcohol use, medical illness, stroke, or epilepsy may be uncovered through discussions with the patient's family members and companions or the patient's medical bracelet and personal possessions.

Physical examination focuses on the ascertaining the underlying cause of SE, localizing the neurologic abnormality, and determining whether complications have occurred. Vital signs are crucial given the cardiovascular complications. (Respiratory failure is an occasional complication of SE but more often results from medications.) The general examination can show signs of infection (by fever, nuchal rigidity, or skin lesions) or systemic illness, such as kidney or liver disease. Signs of head injury or coagulopathy are also important. The neurologic examination also assesses whether seizures are actually continuing in subtle ways.

Laboratory studies

Appropriate laboratory studies include:

• search for metabolic abnormalities, particularly of sodium, calcium, magnesium, and glucose
• kidney, liver, and coagulation assays
• toxicology screening
• anticonvulsant levels and arterial oxygen tension (but treatment must begin before these levels are known)
• blood gas and prolactin levels (to check for the possibility of pseudoseizures)
• pregnancy test for women of childbearing age (partially for purposes of counseling about effects and implications)
• assessment for eclampsia in pregnancy
• urgent computed tomography (CT) scans in cases with asymmetric neurologic exam, seizures with a focal origin, or head injury
• lumbar puncture, if there is any suggestion of central nervous system (CNS) infection or when SE is of unknown cause or difficult to control

EEG

Generalized convulsive SE is diagnosed without an EEG, and treatment begins without it. An EEG is necessary for the diagnosis of nonconvulsive SE, although treatment may begin based on clinical suspicion. EEGs are mandatory when a patient does not respond to initial treatment, because it may be impossible to ascertain clinically whether the patient is postictal or whether electrographic status epilepticus is continuing, requiring further aggressive treatment.

Adapted from: Drislane FW. Status epilepticus. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 149-172.
With permission from Elsevier (www.elsevier.com)
Reviewed and revised January 2004 by Thaddeus Walczak, MD, MINCEP® Epilepsy Care, Minneapolis, MN

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