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CHAPTER 85: Seizures in the Intensive Care Unit 779

CHAPTER Seizures in the Intensive intracranial hemorrhage, sepsis, cardiac arrest, or CNS infection. 11-15 In
one series, 8% of hospitalized comatose patients were found to be in
15
85 Care Unit electrographic status epilepticus, up to 34% of patients in neurological
ICUs, and other series of patients with altered mental status found 37%
15
Katharina M. Busl to have nonconvulsive seizures. Of all patients with status epilepticus,
16
17
Thomas P. Bleck about 80% have nonconvulsive status epilepticus. Seizures are probably
even more frequent in the pediatric ICU, as children in the first year of
life have the highest incidence of SE of any age group studied. 8
KEY POINTS Table 85-1 summarizes the most common causes of SE in adults and
children in the community. An analysis of 204 cases of SE in Virginia
• Seizures are a relatively common occurrence in the intensive care revealed that the primary etiology in children was infection with fever,
unit (ICU), but may be difficult to recognize. followed by remote symptomatic epilepsy, and subtherapeutic levels of
• Seizures that persist longer than 5 to 7 minutes should be treated anticonvulsant drugs. In adults, cerebrovascular disease and low anti-
to prevent progression to status epilepticus. epileptic drug levels were the most prevalent causes. A recent study
8
• Three major factors determine outcome in status epilepticus: type from Brazil found anticonvulsant noncompliance to be the main cause
of seizure, cause, and duration. of SE in patients with a prior history of epilepsy, and CNS infection,
• Electroencephalographic (EEG) monitoring to titrate therapy stroke, and metabolic disturbances predominated in the group without
18
should be implemented in seizing patients who do not awaken previous seizures. A prospective study of neurologic complications in
medical ICU patients determined that two-thirds of patients had a
promptly after institution of antiepileptics, even if tonic-clonic 1
motor activity resolves. vascular, infectious, or neoplastic explanation for their seizures ; meta-
bolic and toxic etiologies are common in the ICU as well. A review of
• Lorazepam is a preferred agent for initial treatment, followed by 100 cases of nonconvulsive SE (NCSE) demonstrated that 14% were due
consideration of additional agents for long-term management or to acute neurologic events, 28% due to acute systemic causes, and 31% due
to “break” status epilepticus. to epilepsy, with the remainder due to multiple causes or a cryptogenic
• Patients with refractory status epilepticus require intubation, etiology, and among patients with NCSE in a comatose state, hypoxia
19
mechanical ventilation, and aggressive treatment with antiepilep- (42%) and stroke (22%) were the most common etiologies. In medical
15
tics titrated to the EEG. ICU patients, electrographic seizures or periodic epileptiform discharges
• The underlying cause of the seizure disorder must be sought in were detected in 22% of patients, with the predominant underlying disease
13
tandem with treatment of the seizure disorder itself. state being sepsis. It is important to realize that the frequency of diagnos-
ing NCSE will rise with implementation of continuous EEG monitoring by
6% to 8% accounting for the increment of investigations. 20
A prospective study of neurologic complications in medical ICU
Seizures are a relatively common occurrence in the ICU, complicating patients showed that having one seizure in the ICU doubled mortal-
the course of about 3% of adult ICU patients admitted for nonneurologic ity. At least 20% of patients with status epilepticus die, 21,22 and up to
1
conditions. Status epilepticus (SE) may be the primary indication for 61% of patients developing SE during hospitalization do not survive.
1
23
admission, or it may occur in any ICU patient during a critical illness. SE in and of itself confers a mortality rate of 26% to adults older than
Seizures are second to metabolic encephalopathy as a cause of neuro- 16 years and 38% to those 60 years and older. Multiple reports corrobo-
8
logical complications (28.1%). A seizure may be the first indication of a rate an especially poor outcome in the elderly. 15,24 The mortality rate of
1
central nervous system (CNS) complication or the result of overwhelm- SE in children is 3% in the general population and 6% in the ICU, and
25
ing systemic disease. Seizures in the setting of critical illness are often
difficult to recognize and require a complex diagnostic and management
strategy. Delay in recognition and treatment of seizures is associated
with increased mortality, thus the rapid diagnosis of this disorder is TABLE 85-1 Causes of Status Epilepticus Presenting From the Community
2
mandatory. Conventionally, status epilepticus referred to a protracted Adults Children
seizure episode or multiple frequent seizures lasting 30 minutes or Prior Seizures No Prior Seizures Prior Seizures No Prior Seizures
longer. However more recently, revised definitions have suggested to
consider seizures lasting for 5 minutes or longer as status epilepticus, Common causes
3-5
and newer guidelines define status epilepticus as five minutes or more Subtherapeutic Ethanol-related Subtherapeutic Febrile seizures
of either continuous clinical and/or electrographic seizure activity, or anticonvulsant anticonvulsant
recurrent seizure activity without recovery between seizures. 6 Ethanol-related Drug toxicity Intractable epilepsy CNS infection
While most seizures will terminate spontaneously within a few
minutes, only half of seizure episodes lasting 10 to 29 minutes will Intractable epilepsy CNS infection Head trauma
5
stop spontaneously and aggressive treatment should be administered to Head trauma
7
prevent ongoing SE. 8 CNS tumor
less common causes
EPIDEMIOLOGY AND OUTCOME
CNS infection Metabolic aberration Anoxic brain injury CNS infection
Limited data are available on the epidemiology of seizures in the ICU. A Metabolic aberration Stroke Head trauma Intractable epilepsy
10-year retrospective study of all ICU patients with seizures at the Mayo
Clinic revealed that 7 patients had seizures per 1000 ICU admissions. Drug toxicity Metabolic aberration Metabolic aberration
8
Our 2-year prospective study of medical ICU patients identified 35 with Stroke
seizures per 1000 admissions. The incidence of generalized convulsive CNS tumor
1
SE (GCSE) in the United States is estimated to be up to 195,000 episodes
per year, but it is unknown how many of these patients require care in Head trauma
9
an ICU. The incidence of SE in the elderly is almost twice that of the CNS, central nervous system.
general population. Nonconvulsive seizures and NCSE are present Adapted with permission from Bleck TP, Dunatov CJ. Seizures in critically ill patients. In: Shoemaker WC, Ayres
10
in a large proportion of comatose patients with traumatic brain injury, SM, Grenvik A, Holbrook PR, eds. Textbook of Critical Care. 4th ed. Philadelphia, PA: WB Saunders; 2000.

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