What are the prognostic factors in Lennox-Gastaut syndrome (LGS)?

Updated: Nov 09, 2018
  • Author: Koshi A Cherian, MD; Chief Editor: Amy Kao, MD  more...
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Answer

Although approximately 20-30% of children with Lennox-Gastaut syndrome (LGS) are free from neurologic and neuropsychologic deficits prior to onset of symptoms (ie, idiopathic LGS), these problems inevitably appear during the evolution of LGS. Factors associated with more common or more severe mental retardation include the following:

  • An identifiable etiology (ie, symptomatic LGS)

  • Onset of symptoms before age 12-24 months

  • More frequent seizures

Average intelligence quotient (IQ) score is significantly lower in patients with symptomatic LGS than in those with cryptogenic LGS (ie, patients for whom no cause of LGS can be identified but a cause is suspected). In one study, IQ testing showed variable degrees of mental retardation in 66% of the cryptogenic group and in 76% of the symptomatic group at first examination. At the last examination, mental retardation was found in 95% of the cryptogenic group and in 100% of the symptomatic group.

A significant correlation exists between age of onset of seizures and mental deterioration. In one study, almost 98% of the patients who had an onset of seizures before age 2 years had definite cognitive impairment, compared with 63% of those with onset after age 2 years.


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