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Reports of seizure frequency may be inaccurate in patients with partial epilepsy

20 February, 2008

Asking people who have partial seizures how often they have seizures
does not appear to provide an accurate count, according to a report in
the journal Archives of Neurology.

The
report suggests that reminding patients to record their seizures in a
diary may not help, because patients may be unaware of some seizures.

The
authors write that seizure frequency is the primary outcome measure for
individual treatment and for clinical trials. Seizures can be detected
objectively using video EEG
(electroencephalogram) monitoring; however, because this method is
expensive, it is used only in certain patients for short time periods.
Doctors most often ask patients to keep seizure diaries.

Dr Christian Hoppe and colleagues at the University of Bonn Medical Centre
studied 91 adult with partial seizures who were admitted to a video-EEG
monitoring unit in 2004 and 2005. The group were fitted with electrodes
and monitored by video for an average of 4½ days. All were asked to
keep a seizure diary and to push a warning button summoning a nurse
when they felt a seizure coming. About half (42) were randomly assigned
to receive daily reminders about documenting all seizures during the
monitoring period.

Patients experienced a total of 582
partial seizures during monitoring but did not report 323 of them.
Patients' level of consciousness before the seizure appeared to affect
their reporting rate - 85 per cent of all seizures that occurred during
sleep were unreported, compared with 32 per cent of seizures that
occurred when patients were awake. Of the seizures recorded by
video-EEG, 43 per cent occurred during sleep, while only 13.9 per cent
of seizures reported by patients occurred during sleep.

"Patients
activated the push-button alarm ahead of 51 seizures (8.8 per cent) but
failed to document 17 (33.3 per cent) of these seizures," the authors
write.

Reporting also varied by seizure type. Fifty-one
percent of patients did not document any complex partial seizures,
which arise from a single brain region and impair consciousness; a
total of 73.2 percent of these types of seizures went unreported. This
compares with 26.2 percent of simple partial seizures-which do not
affect awareness or memory - that were not reported.