People who start showing signs of Lennox-Gastaut syndrome later in life seem to be able to maintain their cognitive and functional abilities, a study has found.
The results of the study, “Cognitive and functional status in late-onset Lennox–Gastaut syndrome: Variation on a classic phenotype,” were published in Epilepsy & Behavior.
Lennox-Gastaut syndrome (LGS) is a rare form of epilepsy characterized by different types of seizures, cognitive impairments, and behavioral problems. Although LGS normally manifests itself during childhood, there have been reports of people who remained undiagnosed until their second decade of life.
“Cognitive impairment in LGS is nearly universal, and behavioral problems have been reported in almost all patients leading to a life of dependency. Better cognitive outcomes have been previously reported with onset of LGS in the second decade of life, (…) but these observations have not been characterized in detail,” the researchers wrote.
In their study, the researchers — from the University of Texas Health Science Center in collaboration with investigators from the Baylor College of Medicine and the University of Florida — described eight cases of late-onset LGS (defined as seizure onset after 10 years of age). Despite having abnormal brain activity associated with the disease, the patients experienced mild cognitive impairments and were able to maintain some degree of independence.
All eight patients (five women and three men) included in the study experienced different types of seizures, including generalized tonic-clonic, atonic, tonic, myoclonic, and atypical absence, which tended to be refractory, or failed to respond, to anti-seizure medications.
The patients exhibited abnormal patterns of brain activity consistent with LGS on electroencephalograms, but they appeared normal in magnetic resonance imaging scans.
Half of the patients had completed high school, two went to college, and two acquired college degrees. Moreover, all of them were able to maintain some independence and to engage in normal daily activities.
“We speculate that a variation of the classic phenotype [manifestation] of LGS can present with preserved cognitive and functional status, often with onset in the second decade of life, and associated with normal brain imaging,” the researchers wrote.
The team also noted that even though people with LGS with “high-functioning” status make up less than 10% of all LGS patients seen in clinical practice, “it is important to identify such patients on a prospective basis for the purposes of effective counseling and for providing direction to appropriate resources and employment opportunities.”
“Further studies comparing characteristics of patients with cognitively and functionally intact late-onset LGS with typical adult patients with LGS may help identify risk factors affecting intellectual and functional outcomes in these patients,” the researchers added.