Status Epilepticus: Current Treatment
`Strategies
`
`Edward M. Manno, MD1
`
`The Neurohospitalist
`1(1) 23-31
`© The Author(s) 2011
`Reprints and permission:
`sagepub.com/journalsPermissions.nav
`DOI: 10.1177/1941875210383176
`http://nhos.sagepub.com
`()SAGE
`
`Abstract
`Status epilepticus is a neurological emergency that is commonly encountered by the neurohospitalist Successful treatment depends
`upon the recognition of prolonged seizure activity and the acute mobilization of available resources. Pharmacologic treatment
`regimens have been shown to decrease the time needed for successful control of seizures and have provided for the rapid
`administration of anticonvulsant medications. Treatment strategies have evolved so that clinicians can administer effective doses
`of medication by whatever routes of administration are immediately available. Traditional algorithms for the treatment of status
`epilepticus have used a stepwise approach to the administration of first-, second-, and third-order medications. More recent options
`have included aggressive anesthetic doses of medications while second-line medications are being titrated.
`
`Keywords
`seizures, status epilepticus, neurological emergencies
`
`Treatment of refractory status epilepticus (RSE) requires
`anesthetic doses of anticonvulsant medication. Early adminis-
`tration of these medications may allow for more successful
`treatment of very recalcitrant forms of status epilepticus. Sig-
`nificant questions remain as to the depth and duration of treat-
`ment for RSE.
`
`Definition
`
`Status epilepticus (SE) can be defined as a seizure of sufficient
`duration to overcome the inherent cellular mechanisms
`designed to terminate the seizure.' Thus, SE becomes a self-
`sustaining process. The International League against Epilepsy
`originally defined SE as 30 minutes of sustained seizure activ-
`ity or 2 or more seizures during this time period without the
`full recovery of the patient.2 Pathologically, however, hippo-
`campal neurons begin to die after 30 minutes of sustained
`seizure activity.3 The limitation of this definition thus sug-
`gests that treatment should not be initiated until pathological
`damage has already been demonstrated.
`Newer operational definitions have suggested that seizures
`lasting longer than 5 minutes are unlikely to discontinue spon-
`taneously and should be treated.4 This is a more useful defini-
`tion since treatment for SE is not delayed. In addition,
`individual unprovoked seizures can on occasion be observed
`and may not warrant aggressive treatment.
`
`epilepticus (GCSE) is the most commonly encountered
`form of SE. Nonconvulsive SE can represent an evolved
`stage of previous GCSE or can occur in complex partial
`status epilepticus (CPSE).
`GCSE is easily recognizable, presenting with generalized
`tonic or clonic activity. As seizures continue, the overt signs
`and symptoms of GCSE may become more repressed and dif-
`ficult to recognize. Treiman5 described this as subtle NCSE. In
`this form of SE, clinical signs may be difficult to ascertain,
`thus requiring close neurological assessment. Subtle signs of
`NCSE may include nystagmus, eye twitching, and/or subtle
`rhythmic finger or toe movements. Husain et a16 reported a
`sensitivity of 100% of NCSE in patients with remote risk
`factors for seizures and ocular movement disorders and rec-
`ommended urgent electroencephalographic (EEG) monitoring
`in these patients. Lothman7 described electrographic and
`physiological changes that may parallel the development of
`these subtle neurological findings.
`Identification of patients with NCSE has also grown in
`importance since the report that a significant percentage of
`patients with head trauma will develop nonconvulsive sei-
`zures during their ICU stay. Vespa et alb recommended
`
`Neurological Intensive Care Unit, Cerebrovascular Center, Cleveland,
`Ohio, USA
`
`Classification and Recognition
`SE can be categorized into convulsive and nonconvulsive
`status epilepticus (NCSE). Generalized convulsive status
`
`Corresponding Author:
`Edward. M. Manno, MD, Neurological Intensive Care Unit, Cerebrovascular
`Center, 9500 Euclid Avenue/S80, Cleveland, OH 44195, USA
`Email: MANNOE@ccf.org (cid:9)
`ARGENTUM Exhibit 1068
` Argentum Pharmaceuticals LLC v. Research Corporation Technologies, Inc.
`IPR2016-00204
`
`EXHIBIT
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`/22d-a
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`24 (cid:9)
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`The Neurohospitalist 1(1)
`
`continuous EEG monitoring in unconscious patients with
`head trauma during their first week. Claassen9 described
`electrographic seizures in one third of patients with intracer-
`ebral hemorrhage undergoing continuous EEG monitoring.
`Seizures were associated with cortical and expanding hemor-
`rhages and had worse outcomes.
`CPSE, the most common form of NCSE, starts focally but
`spreads rapidly to involve other portions of the brain. Patients
`may present confused or combative or in a "twilight state"
`characterized by bizarre behavior and automatisms.10 Initially
`CPSE was thought to be benign, but more recent evidence has
`suggested that aggressive treatment is necessary to avoid cel-
`lular loss and long-term neuropsychological consequences.3
`Myoclonic SE presents as multifocal myoclonus. It occurs
`after severe neurological insults including anoxia and in toxic
`and metabolic states. Prognosis is generally considered poor
`and there is a debate as to whether this represents a true form
`of SE or is a marker for dying and degenerating neurons.1
`A recent study, however, reported neurological improvement
`beyond a vegetative state in 6 patients with postanoxic status
`after therapeutic hypothermia.11
`Absence and focal forms of SE are generally benign and
`will not be addressed. However, the neurohospitalist on
`occasion may need to differentiate nonepileptic or pseudos-
`tatus from SE. Clinical features that may distinguish pseu-
`dostatus from SE include nonrhythmic movements, pelvic
`thrusting, and biting of the tip of the tongue compared with
`the side of the tongue, which is most commonly encoun-
`tered with SE.
`
`Epidemiology
`The incidence of SE has been estimated to be about 60 cases
`per 100 000 population with a mortality of 9 patients per
`100 000 population.7-1° This extrapolates to approximately
`150 000 cases per year in the United States, accounting for
`40 000 deaths per year,12 making SE one of the most com-
`monly encountered neurological emergencies.13'14
`There is a bimodal distribution of SE, with most cases
`occurring in patients less than 1 year of age or older than
`60 years of age. Mortality varies between 7% in the pediatric
`group up to 28% in the elderly.15 Mortality increases with age,
`the duration of SE, and the underlying cause. Worse outcomes
`have been documented after global anoxia, acute stroke,
`trauma, infections, and metabolic disturbances. Patients with
`alcohol or anticonvulsant withdrawal, tumors, and previous
`epilepsy appear to have better outcomes.15
`It is difficult to ascertain how much of the above-listed
`morbidity and mortality can be directly attributed to SE. The
`underlying disease process is oftentimes the primary source
`of morbidity and mortality. The consequences of SE alone,
`however, can be significant. The primary concern is that epi-
`lepsy will develop in about 20% to 40% of patients after a
`single episode of SE. In addition, prolonged seizure activity
`has profound neuropsychological consequences. A chronic
`
`encephalopathy has been described with marked global and
`hippocampal atrophy.'
`
`Pathophysiology
`Brain slice preparations suggest that the development of SE
`includes both an initiation and a maintenance phase.16 SE can
`be initiated through excessive excitatory stimulation but is
`maintained through the lack of appropriate y-aminobutyric
`acid (GABA)—mediated neuronal suppression. This failure
`to suppress the initial excitatory focus may be due to the
`development of changing GABA isoforms. With sustained
`seizure activity, hippocampal GABAA isoforms with different
`pharmacologic properties may develop. This has clinical
`importance since it has been postulated to explain the resis-
`tance to benzodiazepines that develops during SE over time.'?
`Alternatively, SE may be sustained through excitatory
`N-methyl-D-aspartate (NMDA)—mediated neuronal stimula-
`tion. NMDA antagonists have been suggested as a possible
`pharmacologic strategy in the treatment of SE.18
`
`Treatment of Status Epilepticus: Practical
`Aspects
`General Principles
`The primary focus of treatment is the immediate termination of
`the seizure. Accumulating clinical evidence and overwhelming
`experimental evidence have shown that early seizure control
`improves long-term outcome.''' 9'20 In addition, seizures become
`more recalcitrant to treatment as SE progresses.21 Seizures can
`be terminated with relatively low doses of medications if treated
`early. Alldredge et a122 reported that almost 60% of SE was con-
`trolled with 2 to 4 mg of lorazepam when given by emergency
`medical services prior to arrival to the emergency department.
`Adequate resources need to be mobilized quickly with a
`sense of urgency from the involved physicians and support
`staff. Since the most effective method to terminate seizures
`is early treatment, rapid response teams, emergency medicine,
`critical care, or hospitalist personnel should be contacted
`immediately. For personnel not familiar with SE, a useful
`comparison is to suggest that the reverberating circuit encoun-
`tered in SE is similar to the cardiac circuit involved in ventri-
`cular tachycardia.'
`Treatment needs to be initiated as soon as medication is
`available by whatever route is available. Good intravenous
`access is imperative but in some circumstances may not be
`immediately available. Several medications can be given
`intramuscularly, rectally, or sublingually. Table 1 provides the
`dosages of medications that can be given acutely and by the
`most common routes used for those medications when intrave-
`nous access is not immediately available.
`An evaluation to simultaneously identify the underlying
`cause of the seizure and the treatment of secondary complica-
`tions should be initiated. Seizure history and details surrounding
`
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`25
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`Table I. Medication Dosages and Routes of Administration for the
`Treatment of Status Epilepticus
`
`Medication (cid:9)
`
`Route
`
`Dose
`
`Lorazepam (cid:9)
`
`Intravenous
`
`Diazepam (cid:9)
`
`Intravenous
`
`Diazepam
`Midazolam
`Phenytoin
`Fosphenytoin
`Fosphenytoin
`Phenobarbital
`Valproate
`Levetiracetam
`
`Rectal gel
`Intramuscular
`Intravenous
`Intravenous
`Intramuscular
`Intravenous
`Intravenous
`Intravenous
`
`PE, phenytoin equivalents.
`
`4-8 mg initial
`0.1-0.2 mg/kg loading
`5-20 mg initial
`0.15 mg/kg loading
`0.2-0.5 mg/kg initial
`0.07-0.3 mg/kg initial
`20-30 mg/kg loading
`20-30 PE/kg loading
`500-1500 PE initial
`20-30 mg/kg loading
`20 mg/kg loading
`1000-2500 mg initial
`
`the onset and initiation of the seizure can provide helpful diag-
`nostic clues. Changes in medication or alcohol or illicit drug use
`should be ascertained. An exam should focus on possible signs of
`trauma. Routine laboratory studies should be sent including tox-
`icology and antiepileptic drug levels. SE secondary to electrolyte
`abnormalities (ie, hyponatremia, hypocalcemia) can only be suc-
`cessfully treated by correcting the underlying electrolyte
`abnormality. A bedside glucose can be obtained quickly. Thia-
`mine and glucose can be administered quickly if hypoglycemia
`is present. Neuroimaging should be obtained as soon as the
`patient is able to travel and seizures have been controlled. There
`should be a low threshold to obtain cerebrospinal fluid.'
`
`Management Principles
`The management of SE follows the principles of life support.
`Airway management may be as simple as positioning the
`patient to allow for adequate ventilation.23 Oral or nasophar-
`yngeal airways can be placed to ensure airway patency. Bag
`mask ventilation with supplementary oxygen is usually ade-
`quate to avoid significant hypoxemia. Most single seizures
`will resolve by the time resources are mobilized, leaving the
`decision at that point for observation or elective endotracheal
`intubation.24 Prolonged seizures, however, may lead to acute
`airway obstruction and carry a high risk of aspiration. The tim-
`ing of intubation is a clinical decision but usually occurs after
`large doses of sedative medications are given. Rhabdomyolysis
`can occur with SE. Succinyl choline should be avoided in this
`circumstance, given the risk of developing life-threatening
`hyperkalemia. Neuromuscular paralysis may mask subclinical
`seizure activity, and thus the shortest acting neuromuscular
`agent available should be used.
`Adequate intravenous access is crucial for medication
`administration but can be difficult to obtain in the seizing
`patient. Several medications can be given intramuscularly,
`rectally, or sublingually until intravenous access can be ini-
`tiated. Central access may be needed if vasopressor support
`is required.
`
`Medications given in doses to treat SE may cause
`hemodynamic compromise. The neurohospitalist needs to be
`aware of the hemodynamic effects of the medications given
`and be prepared for cardiac arrhythmias, hypotension, or bra-
`dycardia. Frequent monitoring of blood pressure is important.
`Electrocardiographic monitoring should also be available.
`Most patients will be treated in the emergency department
`or in a critical care unit.
`It is important to give medications as soon as possible in
`doses adequate to terminate seizures. Since early termination
`of seizures is crucial to prevent the development of SE, it is
`more important to start a medication that is immediately
`available than to delay treatment while waiting for a medica-
`tion to arrive from pharmacy. The neurohospitalist should
`maximize the dosing of a single drug to high therapeutic or
`supratherapeutic drug levels before adding a second or third
`agent. Standardized protocols for anticonvulsant medica-
`tions have been shown to decrease the time needed to control
`seizure activity.25
`One of the most difficult decisions facing the neurohospi-
`talist is when and how to obtain EEG monitoring. GCSE over
`time may lose the physical features that identify continual sei-
`zure activity. In several instances, overt physical signs of sei-
`zure activity will become attenuated and eventually lost
`despite ongoing electrical seizure activity. In addition, CPSE
`can be clinically difficult to identify and may require EEG
`monitoring. The decision to obtain an emergent EEG is thus
`a clinical one and is oftentimes based on the resources avail-
`able at the hospital. In general if all clinical signs of SE can be
`aborted quickly with first- or second-line drugs, it is unlikely
`that continued seizure activity will be present. However, pro-
`longed treatment and any subtle signs of possible activity
`should prompt urgent EEG evaluation. Patients who remain
`pharmacologically paralyzed should similarly be monitored.
`The availability of EEG monitoring is often a problem.
`When EEG monitoring is not available and there are concerns
`that a patient may be in NCSE, it may be prudent to place the
`patient under a short-acting anesthetic (ie, propofol, thiopen-
`tal) until monitoring can be arranged and the sedative medica-
`tions discontinued. The decision to do this must be weighed
`against the potential side effects of this treatment.
`
`Pharmacological Treatment
`First-Line Medications
`Benzodiazepines are the first medications to be used and are
`the mainstay of treatment. They function by stimulating
`GABAA receptor subunits. This leads to inhibition of neural
`transmission through chloride channel—induced hyperpolari-
`zation of the resting cell membrane!' At high levels, benzo-
`diazepines function in a manner similar to phenytoin.26
`The 3 benzodiazepines used in the treatment of SE are dia-
`zepam, lorazepam, and midazolam. Each drug has slightly dif-
`ferent properties and routes of administration. Diazepam
`
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`The Neu rohospitalist I ( 1 )
`
`achieves higher brain concentrations with an onset of action of
`about 30 seconds. It is, however, highly lipid soluble, leading
`to rapid redistribution and decreases in brain concentrations.
`Clinical effectiveness is only about 20 minutes. Relapse rate
`is high and thus a second drug is required if diazepam is used
`as a first-line drug.27 Diazepam can be given rectally in gel
`form and intramuscularly.
`Midazolam is rarely used as a first-line drug for SE but is
`commonly used as a continuous intravenous infusion for
`RSE. It can be used acutely and is frequently used because
`of physician familiarity and its many routes of administration.
`These include the intramuscular, rectal, sublingual, and nasal
`routes. Midazolam is commonly used out of hospital or with
`children since parents can be trained in administration of this
`medication. It has, however, a very short half-life with a high
`recurrence rate of seizures.27
`Lorazepam is considered the benzodiazepine of choice for
`the treatment of individual seizures and SE. It has a slightly
`longer onset of action, approximating 2 minutes; however, it
`is less lipid soluble than diazepam and has a duration of action
`greater than 12 hours. The results of the Veterans Affairs Sta-
`tus Epilepticus Cooperative Study Group suggested improved
`seizure control with lorazepam,28 although direct comparisons
`of benzodiazepines have shown little difference.29 Lorazepam
`has fewer hypotensive effects and is generally better tolerated
`than diazepam. Initial doses are usually 4 to 10 mg with a
`maximum dose of 0.2 mg/kg. The loading dose for seizure
`control in the VA Cooperative Study was 0.1 mg/kg. Dosages
`for all medications are provided in Table 1.
`
`Second-Line Medications
`Phenytoin or its phosphate ester prodrug fosphenytoin are
`considered the second-line medications with the most use in
`the treatment of SE. Phenytoin is a barbiturate-like compound
`that controls seizure activity by decreasing the recovery rate of
`voltage-activated sodium channels. It is highly protein bound,
`and only the free portion is active. Phenytoin is metabolized
`by the liver and has saturable pharmacokinetics.3° Other med-
`ications that can affect protein binding can have significant
`effects on free phenytoin activity. Thus, levels need to be fol-
`lowed carefully.
`The initial loading dose for phenytoin is 20 mg/kg given
`in non—glucose-containing solutions. If seizures have not
`been terminated by the completion of the loading dose,
`another dose of 10 mg/kg can be given. The goal is to achieve
`supratherapeutic levels (25-30 1.1g/mL) before considering an
`additional medication.31 Concerns of overdosing phenytoin
`are probably overstated, and most side effects will abate as
`levels decrease. Patients previously on phenytoin should be
`given half of the loading doses until phenytoin levels can
`be obtained.
`The side effect profile of phenytoin is primarily cardiovas-
`cular, with hypotension, bradycardia, and QT prolongation
`being common. A drop in systolic blood pressure of greater
`
`than 10 mm Hg occurred in a majority of patients loaded with
`fosphenytoin in one retrospective study.32 Most effects are
`correlated with the infusion rate (maximum rate 50 mg/min)
`and are decreased as the infusion rate is decreased. Physiolo-
`gical monitoring including a continuous electrocardiogram
`(ECG) is required during infusion. These effects are largely
`attributable to the diluent propylene glycol used to increase
`the solubility of phenytoin. There is also a direct medication
`effect on the cardiovascular system.31 The most worrisome
`concern with the use of phenytoin is the severe tissue necrosis
`that can occur with extravasation. The "purple glove syn-
`drome" has been reported in almost 6% of patients receiving
`phenytoin infusions.33
`Fosphenytoin is a phosphate ester prodrug of phenytoin
`that was developed to attenuate the significant side effect
`profile of phenytoin. It is water soluble and therefore can be
`given intramuscularly. It can be administered at a rate of
`150 mg/min. Loading doses are the same as phenytoin and
`may have slightly fewer cardiovascular effects.34 There has
`been some debate about the bioavailability of fosphenytoin
`to phenytoin since the conversion time is about 15 minutes.
`More recent data, however, suggest increased bioavailability
`of fosphenytoin in direct comparison to phenytoin.35 Given
`that fosphenytoin can be given intramuscularly and at a faster
`rate with fewer side effects, it is now preferred over phenytoin
`despite the increased cost. Intramuscular use of fosphenytoin
`has not been directly tested in SE.
`Other medications that could possibly be used in the treat-
`ment of SE include valproic acid and levetiracetam. Valproic
`acid is a short-chain fatty acid that decreases seizure activity
`by prolonging the recovery of voltage-gated sodium channels
`and through effects on GABA metabolism.30 Valproic acid
`can be administered intravenously or rectally. Intravenous
`loading doses of 20 mg/kg have been given at a maximum
`rate of 6 mg/kg/min without hemodynamic compromise.36
`Experience in SE is limited to small series.36-38 In one series
`valproic acid was as effective in terminating SE as pheny-
`toin." Since valproate appears to have few cardiovascular
`effects, it may serve as a second-line drug that could be
`administered in recalcitrant SE prior to giving phenobarbital
`or initiating treatment for RSE.4°
`Levetiracetam inhibits burst firing of neurons without
`affecting normal neural excitability. The exact mechanism
`of this is unknown, but levetiracetam appears to prevent
`hypersyncronization of burst firing and thus propagation of
`seizures. It is metabolized by enzymatic hydrolysis and is
`excreted renally. Dosing needs to be adjusted for renal fail-
`ure.41 Levetiracetam has recently been introduced in intrave-
`nous form and, similar to valproate, appears to have few
`cardiovascular side effects. Side effects are primarily neurop-
`sychiatric, with both agitation and sedation being noted.41 Use
`in SE has been limited to a few case reports 42.43 Doses of
`2500 mg have been shown to be safe and effective when used
`as an additional drug to treat SE." Levetiracetam may be
`particularly effective in absence seizures and CPSE.45
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`Table 2. Intravenous Medications and Dosages for the Treatment of
`Refractory Status Epilepticus
`
`Medication
`
`Midazolam
`
`Pentobarbital
`
`Thiopental
`
`Propofol
`
`Dosage
`
`0.2 mg/kg load
`0.05-2.0 mg/kg/h infusion rate
`5-15 mg/kg load
`0.5-10 mg/kg/h infusion rate
`75- 125 mg load
`1-5 mg/kg/h infusion rate
`3-5 mg/kg load
`I- 15 mg/kg/h
`
`Randomized trials comparing levetiracetam to other first- and
`second-line drugs will need to be performed.
`
`Third-Line Medications
`Phenobarbital is now generally considered a third-line drug in
`the treatment of SE. Phenobarbital is a barbiturate with similar
`properties as the benzodiazepines but is believed to activate a
`varying isoform of the GABAA receptor.21 Phenobarbital is
`used less often due to its long half-life and significant cardior-
`espiratory depressant effects. Dosing is similar to phenytoin.
`
`Refractory Status Epilepticus
`The definition of RSE varies according to the number of med-
`ications used and the time needed to control seizures. For
`practical purposes, RSE occurs when standard loading doses
`of anticonvulsants have proven to be ineffective. RSE has
`been reported to occur in almost one third of patients who are
`being treated for SE.46'47 This percentage may be high
`because of delays in treatment. Some authors have suggested
`that RSE may be avoided with earlier and more aggressive
`treatment.46 RSE requires anesthetic dosages of short-acting
`barbiturates, benzodiazepines, and/or propofol. The dosages
`for these medications are provided in Table 2.
`Midazolam is a short-acting benzodiazepine that is con-
`sidered the first drug of choice of treatment for RSE. It is
`rapidly inducible and has cardiorespiratory side effects that
`are significant but considerably less than encountered with
`propofol or the short-acting barbiturates.48'49 A loading dose
`of 0.2 mg/kg is given with maintenance doses ranging
`between 0.05 and 2.0 mg/kg/h. An escalation of dosing is
`common, as patients may develop a rapid tolerance. Simi-
`larly, withdrawal of this medication will depend upon the
`amount and duration of treatment since benzodiazepine
`withdrawal can complicate treatment if treatment is main-
`tained for an extended period of time. One study comparing
`midazolam to propofol for treatment of RSE found
`improved outcome with midazolam.5° Cost can be limiting.
`Some pharmacies will recommend lorazepam as an alterna-
`tive benzodiazepine. However, clinical experience is limited
`for the use of lorazepam in RSE.1
`
`Propofol is a short-acting nonbarbiturate hypnotic used for
`induction. It has the advantages of rapid induction and elimi-
`nation. Since propofol is commonly used for sedation, it is
`usually immediately available in most emergency rooms or
`intensive care units. Loading dose is 3 to 5 mg/kg with main-
`tenance of 1 to 15 mg/kg/h.48,49
`Propofol has fallen into relative disfavor because of
`increasing anecdotal reports of deaths associated with pro-
`longed or excessive use.51-55 Use of propofol in children is a
`black box contraindication. This has been attributed to the
`development of a metabolic acidosis associated with hypoten-
`sion, rhabdomyolysis, and hyperlipidemia. This has been
`labeled the propofol infusion syndrome and may be related
`to a mitochondrial enzymatic deficiency.55 Feeding regimens
`need to account for the large amount of fat administered with
`propofol.
`Pentobarbital, a short-acting barbiturate, is often used to
`treat RSE.49 The initial loading dose is 5 to 15 mg/kg over
`1 hour. Infusion rates can be maintained at 0.5 to 15 mg/kg/h.
`Pentobarbital is considered relatively short acting; however,
`with prolonged usage its duration of action approaches
`the longer lasting phenobarbital. Pentobarbital has signifi-
`cant cardiovascular effects and will most likely require
`additional vasopressor support. All barbiturates are also
`immunosuppressive, which may lead to an increase in noso-
`comial infections.' Thiopental is metabolized to pentobarbi-
`tal. It has the advantage of oftentimes being readily available
`and can be given in 75- to 125-mg boluses. Infusion rates are
`1 to 5 mg/kg/h.56
`Seizures refractory to the above medication regimens may
`respond to ketamine. Ketamine is a noncompetitive NMDA
`antagonist that can serve both neuroprotective and anticonvul-
`sant roles.57 Animal models have suggested a benefit in
`RSE58; however, the effect of ketamine may be time depen-
`dent, with this agent becoming more effective after 60 minutes
`of seizure activity.59 Clinical experience is limited to a few
`case reports.60'61 Ketamine may be used as an adjunctive treat-
`ment; however, its use remains controversial.
`Isoflurane is a volatile anesthetic that can be used for sei-
`zures resistant to all treatments. It has significant cardiovascular
`effects and requires gas scavenging equipment. It can increase
`intracranial pressure. Nonpharmacological treatments that have
`been used at the case report level have included vagal nerve sti-
`mulation, cortical resection, plasmapheresis, hypothermia, and
`electroconvulsive therapy 62-66
`
`Treatment of Status Epilepticus
`The goal of treatment is the immediate cessation of all seizure
`activity. Simultaneously, treatment should focus on prevent-
`ing the recurrence of seizures, identifying the underlying
`cause, and treating any secondary complications.67'68
`Resources need to be mobilized including nursing, pharmacy,
`rapid response teams, and/or other available medical staff. The
`approach to treatment and diagnosis needs to be deliberate and
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`28 (cid:9)
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`The Neurohospitalist 1(1)
`
`Treatment of Status Epilepticus
`
`Single seizure
`initiate
`evaluation
`
`No
`
`O
`
`Seizure >5 min?
`
`1Yes (cid:9)
`
`Yes
`
`IV lorazepam
`
`O. (cid:9)
`
`
`
`IV phenytoin/fosphenytoin
`
`Establish
`IV access
`I No
`
`Consider
`alternative
`routes of
`administration
`of
`
`Diazepam
`Midazolam
`Fosphenytoin
`
`4
`Valproate
`
`C) Consider
`
`Phenobarbital
`
`(cid:9)
`
`4
`Levetiracetam
`
`S
`E
`
`z
`U
`R
`E
`S
`
`C
`0
`N
`T
`
`N
`U
`
`Refractory status
`epilepticus
`
`I
`Midazolam
`infusion
`
`Propofol
`infusion
`
`Alternative treatment
`
`Ketamine
`
`Isoflurane
`
`3
`Thiopental
`pentobarbital
`infusions
`
`Figure I. Algor'thm for the treatment of status epilepticus. Treatment can proceed along several different pathways to obtain the most imme-
`diate seizure control. See Table I and 2 for medication routes and dosages.
`
`methodical. One possible pharmacological algorithm is
`provided in Figure 1.
`The first task is to determine whether the patient is in SE.
`As mentioned, it is unlikely that continuous seizure activity
`will spontaneously abort after 5 minutes, and any prolonged
`seizure activity should prompt treatment. A prolonged postic-
`tal period after a single or recurrent seizure can make this a
`difficult decision. If there is any suspicion of subclinical sei-
`zure activity, treatment for SE should continue until EEG
`monitoring can be arranged.
`Lorazepam is considered the benzodiazepine of choice for
`the initial treatment of seizures given its pharmacokinetic and
`safety profile. Initial doses should be 4 to 10 mg intrave-
`nously. A loading dose of 0.1 to 0.2 mg/kg should be given
`if seizures are not aborted within 2 to 3 minutes. Diazepam
`or midazolam can also be given but will require the addition
`of a second-line medication. If intravenous access is not
`immediately available, rectal, sublingual, or intramuscular
`benzodiazepines can be administered. Similarly, fosphenytoin
`can be given intramuscularly while intravenous access is
`being obtained.
`If a loading dose of a benzodiazepine is given, it is most
`likely that airway management will require endotracheal intu-
`bation. At this point if seizures continue, one option is to move
`immediately to treatment of RSE (pathway 1 in Figure 1).
`Patients could be given an inducing dose of either propofol
`
`or thiopental and be maintained with an infusion until a
`second-line drug can be added and EEG monitoring can
`evaluate the effectiveness of therapy.
`A second option is to add a second-line medication prior to
`moving to treatment for RSE (pathway 2 in Figure 1). This
`option has been advocated by some authors in an attempt to
`avoid endotracheal intubation.23 However, I warn against
`excessive delays in effective treatment while second-line
`drugs are administered to avoid intubation. Support for this
`argument is provided by the observation that second- and
`third-line medications have decreasing effectiveness for the
`treatment of SE.67
`A third option is to move immediately to loading doses of
`phenobarbital if second-line medications are ineffective
`(pathway 3 in Figure 1). Mayer et a146 have argued that the
`ineffectiveness of second- and third-line medications probably
`reflects a delay in treatment that has made control of seizure
`activity more difficult. This pathway represents the historical
`pathway used in the treatment of SE. A loading dose of phe-
`nobarbital, however, mandates a prolonged hospital course.
`If second- and third-line medications are ineffective, the
`treatment regimen proceeds to treatment for RSE. This man-
`dates EEG monitoring and the titrating of anesthetic levels
`of medications. Opinion has moved away from prolonged
`treatment with propofol in favor of midazolam; however,
`large comparison trials have not been undertaken. In my
`
`Page 00006
`
`

`
`Manno (cid:9)
`
`29
`
`experience, propofol in low doses may serve as a relatively
`safe adjunctive mediation.
`Many questions remain as to the optimal treatment of
`RSE. The depth of induction of anesthetic doses of medica-
`tions is debatable. In practice, medication is usually titrated
`to a burst suppression pattern on EEG monitoring. Smith and
`Bleck,69 however, have argued that all seizure activity should
`be suppressed and that treatment is not adequate until the EEG
`has been rendered flat line.
`The duration of treatment is similarly unknown. Tradi-
`tional teaching has