The clinical and electroencephalographic (EEG) findings of 73 (43 female and 30 male) patients diagnosed with pattern-sensitive epilepsy between 1950 and 1999 were evaluated at the Mayo Clinic, Rochester, MN. The latest seizure and quality-of-life outcomes were determined by contacting patients and relatives by letter or telephone. Seizures, generally absence, myoclonic, or generalized tonic-tonic, began at a mean age of 12.8 years (range, 0.6-32.9 years). Paroxysmal epileptiform discharges in the EEG elicited by patterns were generalized in two-thirds of patients and restricted to posterior head regions in one-third. Patterns that elicited seizures included television in 30 (41%) patients), and environmental objects (eg. window screens, garments, tablecloths, and ceiling tiles) in 29 (40%). An associated photosensitivity was absent in 8 (11%) patients. Complete seizure remission occurred in 25 (45%) of 55 patients followed for >5 years, with a median age at remission of 24 years. Of 58 patients who responded to quality-of-life-related questions, more than two-thirds were not disabled by seizures, and educational achievement, occupational status and family life were unaffected. Pattern-sensitive epilepsy is a recognized subtype of the visually provoked reflex epilepsies. [1]

COMMENT. It is fitting that this comprehensive study of pattern-sensitive epilepsy is reported from the Mayo Clinic. The late Dr Reginald Bickford, who founded the electroencephalography laboratory at the Mayo Clinic, was the first to report visual pattern sensitivity in a child with seizures [2]. The patient, a 6-year-old boy, had absence attacks precipitated by gazing at window screens or patterns of vertical, but not horizontal, parallel black and white lines. He also was sensitive to intermittent photic stimulation. While photosensitive and pattern-sensitive epilepsy share common characteristics, subtle differences are noted. Pattern-sensitive patients without photosensitivity have a higher incidence of focal symptomatic epilepsies, neurologic abnormalities, and focal EEGs (Ped Neur Briefs Nov 1994) [3]. The EEG in pattern-sensitive children shows focal epileptiform discharges in occipital regions, whereas photosensitive patients have generalized polyspike-wave and spike-wave complexes. The Mayo Clinic authors also consider pattern-sensitive epilepsy to represent a distinct subtype of visually-induced reflex epilepsy, warranting routine testing in EEG recordings, and especially in patients with absence, myoclonic, or generalized tonic-clonic seizures. Whereas almost 50% of the patients with pattern-sensitive epilepsy in the Mayo Clinic study achieve complete seizure remission, a group of patients with typical absence seizures triggered by photosensitivity fail to remit, in a recent report from Istanbul, Turkey. [4]