Transcript Seizures - Calgary Emergency Medicine

Seizures
Mark Wahba
August 7, 2003
Statistics
• 10% of population will have 1 seizure in
their lifetime
• 6% of population will have at least 1
afebrile seizure in their lifetime
• Incidence of epilepsy in the population
is <1%
• 1% of ED visits is for seizures
Sub-presentations
• Status epilepticus
• Febrile Seizures
• Medical
management acute
and chronic
Outline
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Definitions
Classification of seizures
Pathophysiology
Clinical Features
Postictal state
Emergency Department Management
Summary
Definitions
Seizure
• “clinical manifestation of excessive,
abnormal cortical neuron activity” Rosen’s
p.1445
• Not a diagnosis but a series of signs
and symptoms
Epilepsy
• “recurring seizures without consistent
provocation” Rosen’s p1445
Ictal
• “pertaining to, marked by, or due to a
stroke or an acute epileptic seizure”
Dorland’s Pocket Medical Dictionary 25th Ed. 1995 W.B. Saunders
Company
Classification of Seizures
Primary and Secondary
• Primary seizure
• Idiopathic/Genetic
• Epilepsy
• Secondary seizure
• aka reactive seizure
• Response to certain
toxic,
pathophysiologic, or
environmental
stress
• Not epilepsy
Generalized and Partial
• Generalized
• Electrical activity
simultaneously
involves both
cerebral
hemispheres
• Loss of
consciousness
• Partial (Focal )
• Electrical activity
limited to part of one
cerebral hemisphere
Partial Seizure
• Simple Partial
• Consciousness is
maintained
• Complex Partial
• Consciousness is
impaired
• Partial with secondary Generalization
• Starts partial then becomes generalized
Cryptogenic Seizure
• Thought to be secondary but identifiable
cause found
Febrile Seizure
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Most common pediatric seizure
2-5% of children between 6mo -5years
20-30% have at least 1 recurrence
Impt. to differentiate febrile seizure from
seizure with fever
Pathophysiology
Pathophysiology
• Not completely
understood
• Knowledge is from
animal studies
• Electrical or
pharmacologic
stimulation applied
to the brain cortex
Recruitment
• Generalized:
• “when the initiating neurons’ abnormal,
increased electrical activity activates adjacent
neurons and propagates until the thalamus
and other subcortical structures are recruited”
Rosen’s p.1446
Recruitment
• Partial:
• Less recruitment and ictal activity does not
cross the midline
Why?
• Unclear
• Disruption of normal structure:
congenital, maturational, acquired
• Disruption of local metabolic or
biochemical function
Neurotransmitters
• acetylcholine-excitatory to cortical
neurons
• gamma-aminobutyric acid (GABA)inhibitory to cortical neurons
• changes in concentration of these NTs
may produce membrane depolarization,
then hyperpolarization, then recruitment
Why is consciousness altered?
• Ictal discharge reaches below the cortex
• Enters brainstem and effects the
reticular activating system
Why does the seizure stop?
• hyperpolarization subsides
• electrical discharges terminate
• “Due to reflex inhibition, loss of
synchrony, neuronal exhaustion,
alteration of the local balance of ACH
and GABA in favor of inhibition” Rosen’s p.
1446
How are seizures confirmed?
• Electroencephalography (EEG)
Clinical Features
Primary Seizures
Simple Partial
• Specific function of initiating neurons
determines the clinical manifestation of
the ictal event
Features
• motor
• focal clonic
movements
• somato-sensory
• special sensory
• paresthesias
• visual, auditory,
olfactory, gustatory
• sweating, flushing
• sense of déjà vu,
fear
• autonomic
• psychic
Complex Partial
• Impairment but not loss of
consciousness
• Amnesia, but may be responsive during
seizure
• Automatisms: lip smacking, swallowing
• Aura: taste, smell, visual
• Maintain high cortical functioning
Generalized Seizures
• Loss of consciousness
• No aura
• May have a vague prodrome or
dysphoric state prior
• Convulsive or Non-Convulsive
Convulsive Generalized Seizures
• ‘Grand-Mal’
• generalized hypertonus
• “rhythmic, violent contractions of
multiple, bilateral, symmetric muscle
groups”
• posterior shoulder dislocation, #
thoracic spine vertebral bodies
• transient apnea
• incontinence: urinary > fecal
• followed by postictal state, headache,
drowsiness that may last for hours
Nonconvulsive Generalized Seizures
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Absence or ‘Petit mal’
Myoclonic
Tonic
Atonic
Absence Seizures
• Begin in childhood
• Sudden cessation of normal, conscious
activity
• dissociative state lasting secs to min
• sudden termination of such state
• No postictal state
Myoclonic and Tonic Seizures
• Sudden, brief muscle group
contractions
• If entire body involved: ‘drop attack’
• No postictal state
Atonic Seizure
• Loss of muscle tone
• May cause ‘drop attack’
Clinical Features
Secondary seizures
Caused by Metabolic
Derangements
Hypoglycemia
• Most common metabolic cause of
seizure activity
• Plasma glucose level <45mg/dL or
2.5mmol/L
• Extremes of age particularly susceptible
Ketotic Hypoglycemia
• Most common cause of childhood
hypoglycemia
• Small for age kids
• “Episodes of symptomatic hypoglycemia
during periods of caloric deprivation or under
provocation by a ketogenic diet” Rosen’s p.1448
• Hypoglycemia and ketonuria
• Dietary management
Osmolar Disorders
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Hyponatremia Na<120mmol/l
Rate of decline is factor
Treat slowly: increase Na by 0.5mmol/h
Treat with 3% NaCl only if seizing
Osmolar Disorders
• Hypernatremia Na>160mmol/l
• Usually due to dehydrating illness
• Correct slowly
others
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Hypocalcemia, Hypoparathyroidism
Hypomagnesemia
Nonketotic Hyperosmolar Hyperglycemia
Uremic Encephalopathy in renal failure
Hypothyroidism
Thyrotoxicosis
High anion gap acidosis
Hypertensive Encephalopathy
Acute Intermittent Porphyria
Infectious Causes
Infectious Causes
• Independent of febrile mechanism
• Usually CNS infections
Meningitis
• 15-40% of pts will seize
• More common at extremes of age
• Partial seizures > general
Meningoencephalitides
• Usually partial motor
• Postictal paralysis common esp. with
herpetic infections
• Presenting sign in 1/3 of cerebral
abscesses
Other
• Neurocysticercosis: parasite in
immigrants from Latin America
• Latent syphilis
• Primary HIV disease and its infections
Drugs and Toxins
Drugs and Toxins
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Antimicrobials
Neuroleptics
Sympathomimetics
Anticholinergics:
tricyclics,
antihistamines
• cocaine
• amphetamines
• PCP
• Withdrawal:alcohol,
BZD
• Overdose:
ASA,theophylline,
INH, Li, phenytoin
• Insecticides
• Rodenticides
• hydrocarbons
Cocaine induced Seizures
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Fever
Rhabdomyolysis
Arrhythmias
Rx: BZD
EtOH Associated seizures
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Overdose
Withdrawal
Must r/o other causes
Rx: BZD
“substitute for the GABA enhancing
effect of ethanol in the CNS” Rosen’s
p.1449
Trauma Associated Seizures
Early
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<1 week post injury
Epi + Sub dural hematomas
Intracerebral Hemorrhage
SAH
Late
• >1week post injury
• 1 year after significant head trauma,
incidence of seizures is increased 12 x
• Severity of head injury is directly
proportional to likelihood of seizures
• 10-15% will develop post traumatic
epilepsy
Malignancy Associated Seizures
Malignancy Associated Seizures
• Primary tumors or metastases
• Usually partial with secondary
generalization
Vasculitic Associated Seizures
Vasculitic Associated Seizures
• Systemic Lupus Erythematosus
• Polyarteritis Nodosa
• Complex partial
Other Neurologic Causes
• Stroke: incidence of seizures 4-15%
• Incidence of epilepsy post stroke is 49%
• Aneurysm and AVM
• Migrainous activation of an epileptic
focus
• MS - 5% of patients
• Neurofibromatosis: café au lait, axillary
freckling
• Tuberous Sclerosis: ash leaf spots,
adenoma sebaceum
• Sturge-Weber syndrome: facial port
wine nevus
• Alzheimer’s Dementia
Gestational Seizures
Gestational Seizures
• Gestational epilepsy
• Hormonal and metabolic changes
unmask underlying epilepsy
• Eclampsia
• Seizures, hypertension, proteinuria,
edema, coma
Pseudoseizures
Pseudoseizures
• Functional
• Not the result of abnormal CNS
electrical activity
• “lower intelligence and have an
underlying anxiety or hysterical
personality disorder” Rosen’s P.1450
• ED evaluation is difficult
• Can co-exist with seizures
Post ictal state
Postictal State
• Decreased level of arousal and
consciousness
• Amnesia
• Headache
• Minutes to hours
• Must monitor and investigate altered
mental status after a seizure
• Airway, pulse oximetry, blood glucose,
cardiac monitoring
• Monitor until recovery
Postictal Paralysis
• “Todd’s Paralysis”
• May follow generalized or complex
partial
• Focal motor deficit
• Lasts up to 24h
• High likelihood of an underlying
structural cause
Neurogenic Pulmonary Edema
• Common, but often subclinical feature of any
CNS insult
• “centrally mediated sympathetic discharge
and generalized vasoconstriction, coupled
with increased pulmonary capillary
membrane permeability” Rosen’s p.1451
• May appear like aspiration pneumonia
• Ventilatory support if necessary
Emergency Department
Management
http://www.seizurerobots.com/
Diagnosis
• Hx of ictal event, known or potential
precipitants and exposures and PMHx
• Thorough Physical Examination
History taking
• 1. Hx of seizures?
• 2. If no, was the event witnessed?
Differential Diagnosis
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Syncope
Hyperventilation
Breath holding
Toxic state: DTs
Metabolic state:
hypoglycemia
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TIA
Narcolepsy
Movement disorders
Psychogenic illness
COLD
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Character-type of seizure
Onset-when, what was pt doing
Location-where
Duration-how long
seizure
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Abrupt onset-no aura
Brief duration-usually <120s
Altered mental status
Purposeless activity
Unprovoked
Postictal state
Previous Seizures
• Focus on:
• Anticonvusant level, med
noncompliance, med change
• Drugs, etoh
• Drug-drug interactions
• Change in ictal pattern
• Cause for lowered seizure threshold
Physical Examination
• Medic alert
• Hypertension,
tachycardia, tachypnea
• Tongue biting
• Shoulder dislocation
• Back pain
• Urinary or fecal
incontinence
• Neurocutaneous signs
Lab
• Stat glucose is vital
• in neurologically N, healthy pt: little
value
• Medically ill: labs
• Anticonvulsant levels
• Tox screen if suspicion of abuse
• BHCG if eclampsia suspected
• Meningitis or SAH: LP if no inc. ICP
Lab abnormalities
• Hypoglycemia- cause/effect?
• Lactic Acidosis
• Rhabdomyolysis
First time seizure
• Never assume it is idiopathic
• 46% will need admission
• Focus on medical, toxicologic,
neurologic cause
First time seizure:
CT scan in the department?
• if you suspect a ‘serious structural
lesion’
Suspect a ‘serious structural lesion’?
• New focal deficit
• Persistent altered
metal status
• Fever
• Trauma
• Persistent headache
• History of cancer
• Anticoagulant use
• Suspicion or known
AIDS
• Age > 40
• Partial onset seizure
• Increased ICP
First time Seizure
• Scan as an outpatient if:
• Complete recovery and no apparent
cause of seizure found
• If follow up questionable: scan in ED
Recurrent Seizures
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Initial stabilization same
Most common cause is med noncompliance
Must measure anticonvulsant levels
Supratherapeutic levels of phenytoin and
carbamazepine may cause seizures
• Be careful about giving loading dose before
checking a serum level
• Hx and PE
Known or Recurrent Epilepsy:
CT scan in dept?
• Same considerations as with first time
seizure
• Also:
• Change in seizure pattern
• Prolonged post-ictal state
Management
Stabilization
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Monitored bed
Oxygen
Pulse oximetry
Heart rate monitor, BP cuff
IV access
Airway
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Anticipatory
Gag reflex suppressed
+/- vomiting
Left lateral decubitus
?Bite block to prevent tongue biting and
to allow suctioning
• +/- nasopharyngeal airway
Apneic or airway threat
• If O2 sat<90% or inability to protect
airway
• Endotracheally intubate
• BZD for induction
• If trismus, may need neuromuscular
blockade
Think:
• If seizure lasts longer than 5 minutes it
is unlikely to stop
• should start thinking about status
epilepticus
• Treat ASAP
Drug Rx of SE
• Starting Rx ASAP has been correlated
with a better response rate to drug Rx,
and lower morbidity
– Lowenstein DH, Alldredge BK
Neurology 1993 (43): 483-8
• < 30 min - 80% stopped
• > 120 min - < 40% stopped
but - retrospective review;
• ? groups comparable
stolen from Dr. S. Bernbaum
Reversible causes
• Hypoglycemia
• Isoniazid
• Eclampsia
• Dextrose
• Pyridoxine
• Magnesium
Medications
• First Line: Benzodiazepines IV
• Directly enhance GABA-mediated neuronal
inhibition
• affect both clinical and electrical
manifestations of seizures
• Terminate seizure activity in 75-90% of pts
• May cause hypotension and respiratory
depression
Lorazepam (Ativan)
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0.1mg/kg/IV
1-2mg/min
Up to 10mg
Peds: 0.05mg to 0.1mg/kg IV
Longer duration of seizure suppression
Diazepam (Valium)
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0.2mg/kg IV
at 2mg/min
up to 20mg
Peds: 0.2-0.5mg/kg IV/IO/ET or 0.51.0mg PR
• Works well rectally, endotracheally,
interosseously
Midazolam (Versed)
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2.5-5.0mg IV
0.2mg/kg IM
Peds: 0.15mg/kg IV then 2-10ug/kg/min
Works well IM
Second line
• anticonvulsants
Phenytoin (Dilantin)
• suppresses neuronal recruitment
• does not suppress electrical activity at
the ictogenic focus
• No sedation or resp depression
• May cause hypotension if given rapid IV
• Takes 30min to infuse
Phenytoin
• 20mg/kg IV at <50mg/min
• Peds: 20mg/kg IV at 1mg/kg/min
• If pt subtherapeutic:
• May give loading dose IV or PO to
boost serum levels
Fosphenytoin
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Phenytoin prodrug
Water soluble
May be administered quickly
Better tolerated, more safe, more stable
than phenytoin
• More difficult to monitor, delayed
hypotension
Fosphenytoin
• 15-20 PE/kg at 100-150mg PE/min
• PE: phenytoin sodium equivalent
• Peds: not established
Phenobarbital
• third-line
• in pediatrics is second-line therapy
• CNS depressant decreases both ictal
and physiologic cortical electrical
activity
• anticipate: sedation and depression of
respiratory drive and BP
Phenobarbital
• 20mg/kg IV at 60-100mg/min
• Ped: same
• May give as IM loading dose
Eclampsia
• Magnesium is not an anticonvulsant
• 4-6g IV followed by 1-2g/h infusion with
hydralazine
• Unexplained efficacy
• BZD effective short term
• Phenytoin may be efficacious-teratogenic
• Should consult Obs/Gyn or have established
protocol
Status Epilepticus
• continuous or rapidly repeating seizures
• no consensus on exact definition - “abn prolonged”
– “no recovery between attacks”
– “20-30 min” --> injury to CNS neurons
– more practical definition: since isolated tonic clonic seizures rarely last > few minutes ...
consider Status if sz > 5 min or 2 discrete sz with
no regaining of consciousness between
• vs. serial sz - close together - regained
consciousness in between
stolen from Dr. S. Bernbuam
CNS damage can occur
• uncontrolled neuronal firing
• excess glutamate (exitatory NT)
• this sustained high influx of calcium ions
into neurons leads to cell death
(“excitotoxicity”)
stolen from Dr. S. Bernbaum
Management of ‘Status’
• Valproate: PR, increases GABA conc.
• Valproate IV 25mg/kg in future
• Barbiturate Coma
Barbiturate coma
• works well but suppresses all brainstem
function
• Neuro, ICU consults recommended: resp
arrest, myocardial depression, hypotension,
dec ICP, dec cerebral perfusion
• phenobarbital 20mg/kg IV at 60mg/min
• pentobarbital 10-15mg/kg IV load then 0.51.0mg/kg/hr infusion
• Need intubation and ventilatory support,
cardiac monitoring, invasive hemodynamic
monitoring, +/- pressors = ICU
Midazolam and Propofol
• midazolam 0.2mg/kg bolus then
0.045mg/kg/h infusion
• propofol 1mg/kg bolus then 2mg/kg/h
infusion
• Hypotension
• Intubation and ICU
Isoflurane Anaesthesia
• Final alternative in refractory status
• Anaesthesia involved
• BZD induction agent + lidocaine
pretreatment
• ICU
Not moving = Not seizing?
• NO
• Visual manifestations of convulsive ictus
are extinguished by neuromuscular
blockade.
• Need electroencephalographic
monitoring arranged
Disposition
• Individualized for pt.
• Home, home with GP follow, neuro
consult in ED, neuro follow up
• Shouldn’t drive for 6 months
• Law varies from province to province
Summary
• Several types of and many causes for
seizures
• History is important
• First seizure likely needs imaging
• Treat immediately
• If seizure lasts >5min think status
epilepticus
• “Sub” areas to consider: febrile seizures,
status epilepticus
References
• Dorland’s Pocket Medical Dictionary 25th Ed. 1995 W.B.
Saunders Company
• Neuroimaging in the emergency department patient presenting
with seizures, Neurology 47:26, 1996.
• Rosen’s Emergency Medicine 5th edition, Marx et al. Mosby,
Toronto, 2002
• Emergency Medicine Secrets 3rd Ed. Markovchick et al. Hanley
& Belfus, Philadelphia 2003
• Seizures in the Emergency Department, Nicholl J.S. et al
http://www.emedicine.com/neuro/topic694.htm
• Status Epilepticus, Stan Bernbaum MD CCFP-EM, May 31,
2001, http://www.calgaryhealthregion.ca/em/