Seizures (Case 54)

Published on 24/06/2015 by admin

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Seizures (Case 54)

Julie Robinson-Boyer MD

Case: A 22-year-old woman was brought in by ambulance. She was at home sitting on the couch when her mother said that she became confused, her eyes rolled back, and then she fell to the floor and started shaking. She had been up late the night before studying for an exam. Upon arrival at the ED she was initially sleepy but then returned to her baseline mental status. During the episode she bit her tongue and had urinary incontinence. Her mother says she had a seizure once as a baby, associated with a fever. She had a normal birth history, normal development, and no prior medical problems. There is no family history of seizures.

Differential Diagnosis

Generalized tonic-clonic seizure

Simple partial seizure

Complex partial seizure

Psychogenic non-epileptic seizure (PNES)

Status epilepticus (SE)

 

Speaking Intelligently

When encountering a patient with a suspected seizure, be sure the patient is stabilized. Then obtain a detailed history and perform a physical and neurologic examination. Consider the differential diagnosis of seizure versus other acute-onset neurologic events, such as syncope, stroke/transient ischemic attack (TIA), and migraine. It is important to find out if the patient has a prior history of seizures and is already being treated with antiepileptic drugs. If the episode is determined to be a seizure, then search for an acute cause, including metabolic abnormalities (hypoglycemia), fever or infection, intoxications (alcohol or drugs), organic lesions (tumor, stroke), and noncompliance with antiepileptic medications. A blood glucose level, blood counts, and electrolyte panels may be helpful in determining the cause of the seizure. In the ED setting, a non-contrast CT scan of the head is the initial imaging modality of choice. If meningitis is suspected, an LP should be performed, usually preceded by a CT scan of the head. Subsequently, you can pursue an MRI of the brain and EEG to complete the workup. The decision whether to treat with antiepileptic medications may vary depending on the characteristics of each individual case.

 

PATIENT CARE

Clinical Thinking

• Seizures are classified as either partial seizures (in which there is a focal or localized onset), generalized seizures (in which the seizure begins bilaterally), or special epileptic syndromes.

Partial seizures are further classified into simple seizures (when there is no alteration in consciousness) and complex seizures (when there is an alteration in consciousness).

Generalized seizures are separated into those that are truly generalized in onset (primary generalized seizures) from those that begin locally and then spread to become generalized (secondarily generalized seizures).

• Classification of seizures is important, because it allows the clinician to make predictions regarding the prognosis and to choose the best medication to treat that specific seizure type.

• A diagnosis of epilepsy is made when a patient has recurrent (two or more) seizures that are unprovoked.

• After a diagnosis of epilepsy is made, one must determine if the presentation fits known patterns of epilepsy syndromes.

• An epilepsy syndrome is a disorder characterized by similar seizure types, clinical features, neurologic abnormalities, and EEG pattern, with a somewhat predictable clinical course and response to antiepileptic drugs.

• Depending on the seizure classification or epilepsy syndrome, one can gain clues as to the underlying etiology of the seizure. Primary generalized epilepsies are most likely genetic or idiopathic, and are not associated with underlying structural abnormalities. On the other hand, partial seizures or secondarily generalized seizures are typically the result of an underlying brain lesion, such as congenital malformations, tumors, prior strokes, traumatic brain injury, or mesial temporal sclerosis.

History

• The history should include detailed questions regarding the characteristics of the seizure, including the prodrome(s), initial manifestations, pattern of evolution, postictal symptoms, level of consciousness, and associated bowel/bladder incontinence or tongue biting. If the patient loses consciousness during the seizure, a witness may be able to provide these details.

• The initial manifestations and pattern of evolution of the seizure can provide clues as to the localization of seizure onset. A history of a preceding aura is also important, as it provides a clue that the seizure is probably focal in origin, with the type of aura providing clues as to the location of the seizure focus. For example, a preceding epigastric aura suggests onset in the mesial temporal lobe.

• Additional information that should be obtained includes birth history; prior episodes of seizure; febrile seizure; history of head trauma, meningitis, or encephalitis; social history including alcohol and/or drug use; and a family history of epilepsy.

Physical Examination

• In adult patients the physical exam is usually unrevealing.

• A focal neurologic sign on exam, such as a hemiparesis, indicates an underlying brain lesion.

• In infants and children the physical exam is important, because one may find dysmorphic features or cutaneous abnormalities that may provide clues as to an underlying disease.

Tests for Consideration

Laboratory studies: Blood glucose, CBC, and electrolyte panel (particularly sodium) should aid in the initial evaluation for a patient with seizure, to identify any acute cause. A urine toxicology screen and a blood alcohol level may be useful in the appropriate clinical setting.

$7, $11, $12, $21, $15

EEG: An EEG records electrical activity from the cerebral cortex and is the most sensitive tool for the diagnosis of epilepsy. It can provide support for the diagnosis of epilepsy, aids in epilepsy classification, and is valuable in determining the risk for seizure recurrence. A normal EEG, however, does not exclude the diagnosis of epilepsy. Sleep deprivation, photic stimulation, or hyperventilation can be used to increase the likelihood of recording EEG abnormalities.

$170

LP: Should be obtained, if the patient is febrile or has meningeal signs, to evaluate for evidence of CNS infection.

$272

Cardiac stress tests, Holter monitors, tilt-table testing, or sleep studies: May be indicated to evaluate some of the non-epileptic disorders.

$297, $65, $298, $795

IMAGING CONSIDERATIONS

→ Neuroradiology: A brain imaging scan should be obtained to rule out the presence of organic lesions, including tumors, stroke, cysticercosis, mesial temporal sclerosis, or other structural abnormalities. CT scanning is easy to obtain, has widespread availability, and is usually the initial study of choice in the ED setting. Brain MRI provides increased sensitivity for lesions that would be missed by CT, such as mesial temporal sclerosis or small tumors.

$334, $534

 

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Generalized Tonic-Clonic Seizure