Seizure

From Anvita Health Wiki

Contents 1 More Specific Terms 2 Introduction 3 Classification 4 Etiology 5 Epidemiology 6 Pathology 7 History 8 Clinical-manifestations 9 Laboratory 10 Diagnostic-procedures 11 Radiology 12 Complications 13 Differential-diagnosis 14 Management 15 More General Terms 16 Additional Terms 17 References

More Specific Terms

• alcohol withdrawal seizure
• atypical (hysterical, psychogenic) seizure or pseudoseizure
• epilepsy
• febrile seizure
• partial seizure
• primary generalized seizure
• seizures in the elderly
• status epilepticus
• Todd's paralysis

Introduction

• A seizure is a sudden change in behavior accompanied by motor, sensory, psychic or autonomic changes. Seizures may last seconds to minutes or persist in the case of status epilepticus. Epilepsy is the tendency towards recurrent seizures.

Classification

• eee International classification of epileptic seizures

Etiology

• pharmaceutical agents: (see drugs causing seizures)
• central nervous system infections ( meningoencephalitis)

• fever with seizures is Herpes
• toxoplasmosis
• cysticercosis
• syphilis
• tuberculosis

• head trauma

• loss of consciousness for at least 1 hour
• penetrating trauma causing cortical injury

• 5% without dura penetration
• 50% with dura penetration & severe head injury

• early within 1 week (usually within 24 hours)

• focal seizures

• late - after 3 months - usually generalized, 70% chronic
• 18 months for glial scar to develop
• seizures occur on impact [5]

• brain tumor

• onset generally 35-55 years
• 10% of adult onset seizures
• astrocytoma, meningioma, CNS lymphoma ( AIDS), metastatic lung cancer
• 15% of brain tumors present with seizures

• cysts
• vascular

• stroke - generally embolic

• seizures may result from previously asymptomatic stroke [8]
• acute hemorrhagic stroke

• vasculitis

• lupus erythematosus
• polyarteritis nodosa

• AV malformations - Sturge Weber syndrome

• birth injury
• degenerative diseases of the CNS

• multiple sclerosis
• tuberous sclerosis
• Alzheimer's disease
• lipidosis ( Tay-Sachs)

• genetic disorders
• cerebral malformations
• metabolic disorders

• hypoglycemia, hyperglycemia
• hypocalcemia
• hyponatremia
• pyridoxine deficiency
• porphyria

• drug or alcohol withdrawal

• alcohol 6-36 hours after cessation
• barbiturate withdrawal
• benzodiazepine withdrawal

• toxic chemicals

• carbon monoxide poisoning
• lead poisoning
• alcohol
• illicit drugs: cocaine, amphetamines
• prescription drugs

• fever

• generally 6 months to 3 years of age
• related to rise in temperature
• increased incidence with infections with:

• gram negative rods
• roseola
• varicella

• syncope

• most often occurs following phlebotomy
• syncopal event precedes seizure

• eclampsia
• allergic

• immunizations
• insect bites

• idiopathic (65-70%)
• precipitants of seizures in patients with seizure disorder

• lack of sleep
• non-compliance
• infection
• pharmacologic agents
• stress

Epidemiology

• seizures most common in patients > 60 years of age

Pathology

• initiation

• hyper-excitable neurons in pathologic tissue
• normal neurons, with environmental abnormalities

• propagation - recruitment of normal neurons

• cortex to subcortex & thalamus

• tonic phase of focal seizure

• cortex to brainstem

• loss of consciousness
• generalized motor activity

• brainstem & thalamus to cortex

• generalized onset seizure
• loss of consciousness

• clonic phase occurs after development of inhibitory circuits

• termination

• inhibitory circuitry
• neurotransmitter depletion
• energy source depletion

History

• timing of onset, duration, description of seizure, past seizures, compliance with medications, aura, incontinence, salivation, vomiting, aspiration, post-ictal weakness, prodrome, history of TIA, stroke or migraine, fever/ chills, diabetes, family history
• eyewitness accounts of stiff limbs, twitches of all limbs, facial color, drooling, head deviation may be correct 1/2 of the time [10]

Clinical-manifestations

• consciousness is generally compromised
• amnesia frequently occurs after seizure
• motor, sensory, psychic or autonomic changes
• most seizures occur in stage 1 sleep
• see specific seizure type

Laboratory

• complete blood count ( CBC)
• serum chemistries

• electrolytes
• serum Ca+2 & serum Mg+2
• serum phosphorous
• serum glucose
• renal function tests
• liver function tests
• antinuclear antibody ( ANA)

• urinalysis & urine toxicology screen
• therapeutic drug monitoring of anticonvulsants
• arterial blood gas ( ABG)
• lumbar puncture with CSF analysis

• indications: fever, altered mental status, severe headache

Diagnostic-procedures

• electroencephalogram ( EEG)

• helps differentiate partial from generalized seizures
• sleep-deprived interictal scalp EEG will show sharp waves, spikes or paroxysmal discharges in most patients with epilepsy
• a normal EEG does not rule out a seizure disorder

• especially so of seizures originating in the medial temporal lobe
• nasopharyngeal recordings or sleep studies may be helpful
• interictal eplileptiform discharges are found on 1st EEG of 25-50% of patients with seizures [5]

• video EEG recording
• 24 hour ambulatory EEG monitoring is generally not helpful

• EKG: evidence of dysrhythmias

Radiology

• magnetic resonance imaging ( MRI) of head

• imaging modality of choice
• all patients

• computed tomography ( CT) of head

• MRI not available
• hemorrhagic stroke suspected

• cerebral angiogram

Complications

• hypoxia & increased muscle activity lead to lactic acidosis
• hypercarbia & respiratory acidosis
• seizure themselves may cause lesions in

• temporal lobe
• amygdala
• hippocampus

• production of minor foci in contralateral hemisphere
• rhabdomyolysis, myoglobinuria & acute renal failure
• hyperpyrexia
• trauma
• aspiration
• recurrent or chronic seizures

• recurrence after a single unprovoked seizure predicted by

• partial seizure
• Todd's paralysis
• family history of epilepsy
• age > 65 years
• abnormal findings on neurological exam
  

• disease interaction(s) of obstructive sleep apnea (OSA) with seizures

Differential-diagnosis

• syncope

• generally no headache, confusion, weakness
• generally no tonic- clonic activity

• narcolepsy

• unconscious, but arousable
• no incontinence
• no tonic- clonic activity

• transient ischemic attack ( TIA)

• consiousness generally not impaired
• generally no tonic/ clonic activity
• may have persistent focal findings

• migraine headache

• duration hours vs 1-2 minutes for seizure
• no tonic- clonic activity
• altered consciousness is rare

• cataplexy

• awake, but no voluntary movement
• no incontinence
• no tonic- clonic activity

• extrapyramidal disorders

• tics - normal Tourette's syndrome
• dystonia - torticollis
• tardive dyskinesia - antipsychotic agents
• chorea - hereditary, infectious
• athetosis - perinatal hypoxia
• hemiballism - subthalamic nuclei injury
• tremor - Parkinson's disease, familial tremor
• myoclonus - associated with sleep

• child breath-holding spells
• hysteria
• paroxysmal vertigo

• duration minutes to days
• nausea, ataxia, tinnitus
• alert after episode

• metabolic encephalopathy
• pseudoseizure

• long duration, 10-30 minutes
• aynchronous movement of arms & legs
• on & off time course

Management

• correction of underlying etiology (first line)
• pharmacologic

• depends upon type of seizure & patient's ability to tolerate side effects
• indications for therapy

• patient with single, unprovoked, generalized tonic-clonic seizure may not require therapy
• 20% recurrence rate in next 5 years if neurologic examination, EEG & MRI are normal
• it is reasonable NOT to start therapy for an initial single seizure, especially if a preventable precipitating event can be identified

• alcohol
• hypoglycemia
• syncope
• fever

• seizures requiring pharmacologic therapy:

• absence seizures
• partial seizures
• seizures associated with juvenile myoclonic epilepsy
• recurrent generalized tonic-clonic seizures
• seizures associated with abnormal EEG

• early therapy has no effect on long-term prognosis [9]

• start with single agent, increase until seizures are controlled or adverse effects occur
• therapeutic monitoring for anticonvulsive agents

• important for patients with:

• indadequate seizure control
• signs or symptoms of toxicity

• appropriate dose is dose that controls seizures in the absence of adverse effects, regardless of serum levels

• non-compliance is most important cause of seizures in epileptic patients
• consider withdrawing anticonvulsant therapy for patients

• without seizures for 2 years with normal EEG
• known precipitant of seizures without underlying brain disease
• anticonvulsive therapy should be tapered, not abruptly discontinued

• relapse after stopping anticonvulsants in adults is 25-60% over 2 years [5]
• 30-40% of patients do not respond to anticonvulsants [5]
• see specific seizure type for specific agents

• surgery

• referral for patients not controlled by medication

• failure to control seizures despite adequate trials of 2 appropriate anticonvulsants [5]

• surgical resection of epileptic focus can provide relief or cure

• vagus nerve stimulation

• treatment option for medically refractory seizures in patients not candidates for traditional surgery

• notification of health department

• seizure-free for 6 to 12 months before a patient with seizure disorder can legally drive (Calif); differs in different states [6]

• patient education:

• avoid swimming, heights, driving, operating heavy equipment
• keep seizure diary for return visits to physician

• risk of congenital malformations is higher in offspring of epileptic mothers

• risk increases slightly with anticonvulsive therapy [5%]
• all anticonvulsive agents implicated
• maximal fetal risk during 1st 6 weeks of gestation
• folic acid (1 mg/day) should be administered throughout pregnancy

• supplement Ca+2 & vitamin D in women ( bone mineral density may be reduced by anticonvulsants [7])

• Follow-up:

• every 3-6 months to evaluate seizure control

More General Terms

• disease/disorder primarily affecting brain
• sign/symptom

Additional Terms

• International classification of epileptic seizures
• seizures in the elderly

References

1. Harrison's Principles of Internal Medicine, 13th ed. Companion Handbook, Isselbacher et al (eds), McGraw-Hill Inc. NY, 1995, pg 829-39
2. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 1034-35
3. Alan Gelb, UCSF, Department of Emergency Services, San Francisco General Hospital, 1998
4. Chan & Winkle, Diagnostic History & Physical Examination, Current Clinical Strategies Publishing. Laguna Hills, 1996
5. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15 American College of Physicians, Philadelphia 1998, 2006, 2009
6. Journal Watch 22(1):8, 2002 [1]
7. Prescriber's Letter 10(1):4 2003
8. Journal Watch 24(10):79-80, 2004 Cleary P, Shorvon S, Tallis R. Late-onset seizures as a predictor of subsequent stroke. Lancet. 2004 Apr 10;363(9416):1184-6. PMID: [2]
9. Journal Watch 25(15):117, 2005 Marson A, Jacoby A, Johnson A, Kim L, Gamble C, Chadwick D; Medical Research Council MESS Study Group. Immediate versus deferred antiepileptic drug treatment for early epilepsy and single seizures: a randomised controlled trial. Lancet. 2005 Jun 28;365(9476):2007-13. PMID: [3]
10. Thijs RD et al. Transient loss of consciousness through the eyes of a witness. Neurology 2008 Nov 18; 71:1713. PMID: [4]
11. NIH Institute & Center Resources [5]
12. National Guideline Clearinghouse
    - Practice parameter: evaluating an apparent unprovoked first seizure in adults (an evidence-based review). Report of the Quality Standards Subcommittee of the American Academy of Neurology and the American Epilepsy Society. ngc-guideline: [6]
    - Reassessment: neuroimaging in the emergency patient presenting with seizure (an evidence-based review). Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology ngc-guideline: [7]
    - Use of serum prolactin in diagnosing epileptic seizures. Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. ngc-guideline: [8]
    - Seizures-child. (American College of Radiology) ngc-guideline: [9]
    - Care of the patient with seizures. 2nd edition. American Association of Neuroscience Nurses ngc-guideline: [10]

seizure; epileptic seizure