Cognitive Decline in Severe Intractable Epilepsy

• Published in: Epilepsia (Copenhagen) 2005-11, Vol.46 (11), p.1780-1787
• Main Authors: Thompson, Pamela J., Duncan, John S.
• Format: Article
• Language: English
• Subjects: Adult; Anticonvulsants. Antiepileptics. Antiparkinson agents; Biological and medical sciences; Cognition Disorders - diagnosis; Cognition Disorders - epidemiology; Cognitive decline; Comorbidity; Epilepsy; Epilepsy - diagnosis; Epilepsy - epidemiology; Epilepsy - therapy; Epilepsy, Tonic-Clonic - diagnosis; Epilepsy, Tonic-Clonic - epidemiology; Epilepsy, Tonic-Clonic - therapy; Female; Follow-Up Studies; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Humans; Intelligence; Longitudinal Studies; Magnetic Resonance Imaging; Male; Medical sciences; Nervous system (semeiology, syndromes); Neurology; Neuropharmacology; Neuropsychological Tests - statistics & numerical data; Neurosurgery; Pharmacology. Drug treatments; Prognosis; Regression Analysis; Retrospective Studies; Seizures; Severity of Illness Index; Skull, brain, vascular surgery; Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases; Syncope - diagnosis; Syncope - epidemiology; Treatment Outcome; United Kingdom - epidemiology
• ISSN: 0013-9580; 1528-1167
• DOI: 10.1111/j.1528-1167.2005.00279.x

Purpose: To explore the relation between seizure‐related variables and cognitive change in patients with severe intractable epilepsy. Methods: A retrospective analysis of data from 136 patients who had undergone a cognitive assessment on two occasions at an interval of ≥10 years. Cognitive measures included tests of memory and executive skills in addition to intelligence quotients (IQ). Details were available regarding seizure type and frequency in the intertest interval. Results: Cognitive decline was severe and occurred across a wide range of cognitive functions. The frequency of generalised tonic–clonic seizures was the strongest predictor of decline. Complex partial seizure frequency was associated with a decline in memory and executive skills but not in IQ. Seizure‐related head injuries and advancing age carried a poor cognitive prognosis, whereas periods of remission were associated with a better cognitive outcome. Early age at onset was not implicated, and duration of epilepsy was a much less potent predictor of cognitive decline than has been reported in cross‐sectional studies. No evidence indicated that a higher level of cognitive function protected against cognitive decline. Conclusions: Our findings, together with those from animal studies and surgically treated patients, suggest that seizures can have a direct adverse effect on cognition and that good seizure control even after years of intractability can have a beneficial impact on cognitive prognosis. This study was based on individuals who merited two cognitive assessments ≥10 years apart and hence is biased in favor of those with the most severe forms of refractory epilepsy and those with decline.