SEIZURE DISORDERS IN CHILDREN

See also Febrile Seizures

I. "Idiopathic epilepsy" = several distinct syndromes

  1. All consist of recurrent sz (any type; 1 type us. predominates) w/o identifiable cause
  2. "Petit-mal" epilepsy:
  1. Us. presents in young, otherwise well child
  2. Absence sz (staring, arrested activity)
  3. Sz often triggered by hyperventilation
  4. Us. nl neuro px, intelligence
  5. In its pure form, almost never due to structural lesion
  6. 80% of pts have no sz after puberty
  7. 10% have persistent absence sz
  8. 10% go on to have tonic-clonic sz
  1. "Photosensitive" epilepsy
  1. Us. presents in late childhood/adolescence
  2. Sz triggered by flickering lights
  3. Myoclonic or tonic-clonic sz
  1. "Benign focal epilepsy of childhood" ("Sylvian sz")
  1. Partial motor sz, esp. clonus of facial mm.
  2. Often occur during sleep
  3. Nl neuro px, intelligence
  1. "Grand-mal epilepsy"
  1. Onset up to adolescence
  2. Tonic-clonic sz; first one often triggered by fever
  3. From 1 sz/yr up to >3/wk
  4. Us. can't identify precipitant
  5. T-C sz run risk of anoxic brain damage; greater risk in kids; also higher incidence of intellectual impairment, behavior G's, rarely ataxia or spasticity

II. Diagnostic modalities:

  1. EEG--specific patterns for the various syndromes
  1. 30% of pts with Grand-mal have nl interictal EEG
  1. Brain imaging (CT or MRI)
  1. Usually normal in idiopathic epilepsy, except for lesions representing anoxic damage due to prior seizures
  2. Somewhat controversial as to when/if needs to be done in children with unexplained seizures
    1. One recommendation (I don't remember where) was to do it for recurrent seizures other than absence
    2. Clinically significant findings were seen on brain imaging in 8% of pts in one retrospective review of 500 children presenting to an emergency department with new-onset (non-febrile) seizures (Peds. 111:1, 2003--JW).  Sig. risk factors for clinically significant findings on brain imaging were:
      1. Sickle-cell anemia
      2. Bleeding disorders
      3. Closed head injuries
      4. Age < 33mos and focal seizures
  1. Blood chemistry: Glu, Lytes, Ca, Mg, Pb
  1. If also have MR, check urine AA/organic acids
  1. Generally no focal neurol. findings in idiopathic epilepsy except for post-ictal G's: Babinsky, DTRs, anisocoria

III. Diff. Dx:

  1. Neurocutaneous syndromes--May see phacomata on fundoscopy
  2. Space-occupying intracranial lesions, e.g. tumors, vascular malformations
  3. "Pseudoseizuser"--e.g. conversion disorder or malingering; can coexist with real seizures.
  4. Benign paroxysmal vertigo
  5. Other: migraine, cardiac syncope, narcolepsy

IV. Acute seizure management in children

  1. ABCs! Us. just need oral airway, O2, suction
  2. Position pt on side
  3. Draw blood for Glu, Lytes, Ca, Mg, & drug levels
  4. If hypoglycemia is possible, give D20W 2ml/kg
  5. Diazepam 0.3mg/kg IV over 2-3min up to 10mg
  1. may cause transient resp. depression necessitating ventilatory assistance
  2. Lasts 30-60min, so also give an anticonvulsant with longer t-1/2, especially if diazepam doesn't stop the sz, e.g.
  1. Intranasal Midazolam 0.2mg/kg was as effective as IV Diazepam at dose above in a randomized trial of 44 kids with febrile sz x > 10min duration (BMJ 321:83, 2000--JW)
  2. Phenobarbital 10mg/kg IV over 2-3min
  3. If sz continues >10min with above tx, repeat dose of diazepam or repeat phenobarb to total of 20mg/kg or give dilantin 20mg/kg over 15-20min with EKG monitoring
  4. If sz persist >30min without regaining consc. on meds, call anesthesia & give slow IV Amobarbital; be prepared to intubate

V. Tx of idiopathic epilepsy:

  1. Begin with 1 drug @ low dose, dose until sz disappear or until toxicity appears or blood levels exceed therapeutic range.
  2. If either of the latter occur, add 2nd drug or try new one alone
  3. Maintain tx until sz-free x 3-4y; less if very young
  1. Relapse occurs after d/c in 10-15%
  1. When d/c-ing, taper over months
  2. Role of EEG in anticonvulsant d/c is controversial
  3. Monitor levels of anticonvulsants--note that most have very long t-1/2
  4. Anticonvulsant meds:
  1. No sig diff. in safety in older kids. Can combine 2 or 3 of these; never all 4
  2. Petit mal--Ethosuximide 1st; Add Phenobarb or Acetozolamide for 2nd-line
  3. Phenobarb--1st choice in preschoolers; not necessarily so in older kids. Can cause hyperactivity requiring G in drugs; also question of lowering intelligence over long-term.
  4. Also P-barb derivatives mephobarbitol & primidone
  5. Dilantin (diphenylhydantoin, "DPH", phenytoin)--can cause acromegalic facies. Hard to control blood level. OD causes nau/vom, druwsiness, pseudodementia, & ataxia.
  6. Carbamazepine ("CMZ")--must monitor CBC & LFTs; antidepressant f/x (?)
  7. Valproic acid--hepatotoxic, esp. in preschoolers
  8. Felbamate--May cause aplastic anemia (none reported in pts > 13yo as of 2000), somnolence, nausea, vomiting, & gait abnormalities
  9. Gabapentin
  10. Lamotrigine--Causes sig. skin rashes in 12%; can progress to Stevens-Johnson Sd. or toxic epidermal necrolysis
  11. Tiagabine
  12. Topiramate
  13. Vigabatrin--Investigational as of 2000

VI. Long term outcomes

  1. Results of a Finnish study that followed 245 children with epilepsy for 30y showed that 64% had been sz-free for > 5y at final f/u and most were not on meds (NEJM 338:1715, 1998--JW)
  2. Other good prognostic signs (don't know source where I got this):
    1. Antisz meds begun early after dx
    2. Nl neuro px
    3. >1 type of sz
    4. Onset late in childhood