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Seizures

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.

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Seizures

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  1. Seizures Mark Wahba August 7, 2003

  2. 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

  3. Sub-presentations • Status epilepticus • Febrile Seizures • Medical management acute and chronic

  4. Outline • Definitions • Classification of seizures • Pathophysiology • Clinical Features • Postictal state • Emergency Department Management • Summary

  5. Definitions

  6. Seizure • “clinical manifestation of excessive, abnormal cortical neuron activity” Rosen’s p.1445 • Not a diagnosis but a series of signs and symptoms

  7. Epilepsy • “recurring seizures without consistent provocation” Rosen’s p1445

  8. 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

  9. Classification of Seizures

  10. Primary seizure Idiopathic/Genetic Epilepsy Secondary seizure aka reactive seizure Response to certain toxic, pathophysiologic, or environmental stress Not epilepsy Primary and Secondary

  11. Generalized Electrical activity simultaneously involves both cerebral hemispheres Loss of consciousness Partial (Focal ) Electrical activity limited to part of one cerebral hemisphere Generalized and Partial

  12. Partial Seizure • Simple Partial • Consciousness is maintained • Partial with secondary Generalization • Starts partial then becomes generalized • Complex Partial • Consciousness is impaired

  13. Cryptogenic Seizure • Thought to be secondary but identifiable cause found

  14. Febrile Seizure • 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

  15. Pathophysiology

  16. Pathophysiology • Not completely understood • Knowledge is from animal studies • Electrical or pharmacologic stimulation applied to the brain cortex

  17. 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

  18. Partial: Less recruitment and ictal activity does not cross the midline Recruitment

  19. Why? • Unclear • Disruption of normal structure: congenital, maturational, acquired • Disruption of local metabolic or biochemical function

  20. 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

  21. Why is consciousness altered? • Ictal discharge reaches below the cortex • Enters brainstem and effects the reticular activating system

  22. 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

  23. How are seizures confirmed? • Electroencephalography (EEG)

  24. Clinical Features Primary Seizures

  25. Simple Partial • Specific function of initiating neurons determines the clinical manifestation of the ictal event

  26. motor somato-sensory special sensory autonomic psychic focal clonic movements paresthesias visual, auditory, olfactory, gustatory sweating, flushing sense of déjà vu, fear Features

  27. 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

  28. Generalized Seizures • Loss of consciousness • No aura • May have a vague prodrome or dysphoric state prior • Convulsive or Non-Convulsive

  29. Convulsive Generalized Seizures • ‘Grand-Mal’ • generalized hypertonus • “rhythmic, violent contractions of multiple, bilateral, symmetric muscle groups”

  30. posterior shoulder dislocation, # thoracic spine vertebral bodies • transient apnea • incontinence: urinary > fecal • followed by postictal state, headache, drowsiness that may last for hours

  31. Nonconvulsive Generalized Seizures • Absence or ‘Petit mal’ • Myoclonic • Tonic • Atonic

  32. 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

  33. Myoclonic and Tonic Seizures • Sudden, brief muscle group contractions • If entire body involved: ‘drop attack’ • No postictal state

  34. Atonic Seizure • Loss of muscle tone • May cause ‘drop attack’

  35. Clinical Features Secondary seizures

  36. Caused by Metabolic Derangements

  37. Hypoglycemia • Most common metabolic cause of seizure activity • Plasma glucose level <45mg/dL or 2.5mmol/L • Extremes of age particularly susceptible

  38. 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

  39. Osmolar Disorders • Hyponatremia Na<120mmol/l • Rate of decline is factor • Treat slowly: increase Na by 0.5mmol/h • Treat with 3% NaCl only if seizing

  40. Osmolar Disorders • Hypernatremia Na>160mmol/l • Usually due to dehydrating illness • Correct slowly

  41. others • Hypocalcemia, Hypoparathyroidism • Hypomagnesemia • Nonketotic Hyperosmolar Hyperglycemia • Uremic Encephalopathy in renal failure • Hypothyroidism • Thyrotoxicosis • High anion gap acidosis • Hypertensive Encephalopathy • Acute Intermittent Porphyria

  42. Infectious Causes

  43. Infectious Causes • Independent of febrile mechanism • Usually CNS infections

  44. Meningitis • 15-40% of pts will seize • More common at extremes of age • Partial seizures > general

  45. Meningoencephalitides • Usually partial motor • Postictal paralysis common esp. with herpetic infections • Presenting sign in 1/3 of cerebral abscesses

  46. Other • Neurocysticercosis: parasite in immigrants from Latin America • Latent syphilis • Primary HIV disease and its infections

  47. Drugs and Toxins

  48. Antimicrobials Neuroleptics Sympathomimetics Anticholinergics: tricyclics, antihistamines cocaine amphetamines PCP Withdrawal:alcohol, BZD Overdose: ASA,theophylline, INH, Li, phenytoin Insecticides Rodenticides hydrocarbons Drugs and Toxins

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