In 31 consecutive patients who were admitted to an epilepsy monitoring
unit, we prospectively determined whether the patients were aware of
having seizures. On admission, all patients stated that they knew of a
t least some of their seizures. Eight of 23 with classifiable epilepti
c seizures recognized that they were occasionally unaware of their sei
zures. During telemetry, following full recovery of consciousness afte
r each seizure, Ne asked the patients whether they had recently had a
seizure. For control purposes, we asked the patients the same question
at random times. Among patients with seizures, there were no false-po
sitive answers. Only 6 of 23 (26%) of the patients with epilepsy were
always aware of their seizures, including complex partial and secondar
ily generalized events, and 7 of 23 (30%) were never aware of any seiz
ures. Self-reporting of seizures was unreliable: Patients reporting th
e lowest baseline frequency of seizures had the highest fraction of un
recognized seizures. Seizure awareness was lowest for patients with te
mporal lobe foci, especially on the left side. Patients with primarily
generalized epilepsy were more likely to be aware of tonic-clonic sei
zures than were patients with secondarily generalized partial seizures
. All four patients with nonepileptic attacks believed that they alway
s knew of their seizures, but only three of the four patients actually
did always know. Unrecognized seizures are frequent and should be con
sidered in patient management and in studies.