title: Temporal anteroinferior encephalocele: An underrecognized etiology of temporal lobe epilepsy?
abstract: OBJECTIVE
  To report the increasing frequency with which temporal anteroinferior encephalocele is a cause of adult temporal lobe epilepsy, to illustrate the clinical and imaging characteristics of this condition, and to report its surgical treatment in a series of 23 adult patients.
  
  
  METHODS
  Epilepsy patients diagnosed with temporal anteroinferior encephalocele from January 2006 to December 2013 in a national epilepsy reference center were included in this noninterventional study.
  
  
  RESULTS
  Twenty-three epilepsy patients (14 female, mean age 43.8 years) were diagnosed with temporal anteroinferior encephalocele in our institute. Thirteen patients had ≥2 encephaloceles; 7 cases presented bilaterally. The estimated frequency of this condition was 0.3% among MRI examinations performed due to newly diagnosed epilepsy (n = 6) and 1.9% among drug-resistant patients referred to our center (n = 17). Nine patients with local encephalocele disconnection (n = 4) or anterior temporal lobectomy and amygdalohippocampectomy (n = 5) have become seizure-free (Engel 1) for a mean 2.8 years (range 3 months-6.2 years) of follow-up. Three patients with local encephalocele disconnection were almost seizure-free or exhibited worthwhile improvement. Histologically, all 12 surgical patients had gliosis at the base of the encephalocele; some had cortical laminar disorganization (n = 5) or mild hippocampal degeneration (n = 1).
  
  
  CONCLUSIONS
  The possibility of a temporal encephalocele should be considered when interpreting MRI examinations of patients with medically intractable focal epilepsy. These patients can significantly benefit from unitemporal epilepsy surgery, even in cases with bilateral encephaloceles.
authors.affiliation: From the Departments of Clinical Radiology (T.S., R.V.), Neurology (L.J., R.K.), Clinical Neurophysiology (E.M.), and Neurosurgery (A.I.), Kuopio University Hospital, Finland; and the Institute of Clinical Medicine (T.S., E.M., R.K., R.V.), University of Eastern Finland, Kuopio.
authors.forename: Taavi
authors.initials: T
authors.lastname: Saavalainen
authors.affiliation: From the Departments of Clinical Radiology (T.S., R.V.), Neurology (L.J., R.K.), Clinical Neurophysiology (E.M.), and Neurosurgery (A.I.), Kuopio University Hospital, Finland; and the Institute of Clinical Medicine (T.S., E.M., R.K., R.V.), University of Eastern Finland, Kuopio.
authors.forename: Leena
authors.initials: L
authors.lastname: Jutila
authors.affiliation: From the Departments of Clinical Radiology (T.S., R.V.), Neurology (L.J., R.K.), Clinical Neurophysiology (E.M.), and Neurosurgery (A.I.), Kuopio University Hospital, Finland; and the Institute of Clinical Medicine (T.S., E.M., R.K., R.V.), University of Eastern Finland, Kuopio.
authors.forename: Esa
authors.initials: E
authors.lastname: Mervaala
authors.affiliation: From the Departments of Clinical Radiology (T.S., R.V.), Neurology (L.J., R.K.), Clinical Neurophysiology (E.M.), and Neurosurgery (A.I.), Kuopio University Hospital, Finland; and the Institute of Clinical Medicine (T.S., E.M., R.K., R.V.), University of Eastern Finland, Kuopio.
authors.forename: Reetta
authors.initials: R
authors.lastname: Kälviäinen
authors.affiliation: From the Departments of Clinical Radiology (T.S., R.V.), Neurology (L.J., R.K.), Clinical Neurophysiology (E.M.), and Neurosurgery (A.I.), Kuopio University Hospital, Finland; and the Institute of Clinical Medicine (T.S., E.M., R.K., R.V.), University of Eastern Finland, Kuopio. ritva.vanninen@kuh.fi.
authors.forename: Ritva
authors.initials: R
authors.lastname: Vanninen
authors.affiliation: From the Departments of Clinical Radiology (T.S., R.V.), Neurology (L.J., R.K.), Clinical Neurophysiology (E.M.), and Neurosurgery (A.I.), Kuopio University Hospital, Finland; and the Institute of Clinical Medicine (T.S., E.M., R.K., R.V.), University of Eastern Finland, Kuopio.
authors.forename: Arto
authors.initials: A
authors.lastname: Immonen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D038481:Anterior Temporal Lobectomy / Q000379:methods; D015331:Cohort Studies; D004569:Electroencephalography; D004677:Encephalocele / Q000150:complications / Q000473:pathology* / Q000601:surgery; D004833:Epilepsy, Temporal Lobe / Q000209:etiology / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019291:Skull Base / Q000473:pathology*; D013702:Temporal Lobe / Q000473:pathology*; D016896:Treatment Outcome; D055815:Young Adult