Status epilepticus: pseudoseizures were more likely if fits were atypical.

Clinical bottom line (level 4)

  1. Pseudoseizures were more likely in patients with a psychiatric history, an unexplained illness or attacks thought to be atypical.
  2. Patients that called out or resisted examination were more likely to have pseudoseizures.
  3. An extensor plantar response made a pseudoseizure less likely.
  4. Iatrogenic complications in patients with pseudoseizure were common - over half had a respiratory arrest.
Howell et al: Quarterly Journal of Medicine 1989; 71 (266): 507-519
Expires November 2003

The study

Setting: university hospital, UK

26 patients (aged ?, 62% female) 13 patients with pseudoseizures mimicking status epilepticus (i.e. misdiagnosed with status epilepticus and treated with repeated or continual parenteral short-acting sedatives or anticonvulsants), compared with 13 control patients with status epilepticus

Non-independent unblinded reference standard, applied in all patients from a consecutive inappropriate spectrum.
Reference standard:
  • diagnosed by senior neurologist using clinical, neurophysiological ± ictal EEG.
Diagnostic test: clinical findings

The evidence


diagnostic test pseudoseizure status epilepticus LR+
(95% CI)		 LR-
(95% CI)
psychiatric history 10 1 10
(1.5 to 67) 		0.25
(0.092 to 0.68)
unexplained illness 8 0 infinity
(3.0 to infinity) 		0.38
(0.19 to 0.76)
attacks thought atypical by staff 13 2 6.5
(1.8 to 23) 		0.0
(0.0 to 0.22)
conscious yet having seizure with bilateral motor activity 8 1 8.0
(1.2 to 55) 		0.42
(0.21 to 0.84)
vocalisation 8 2 4.0
(1.0 to 15) 		0.45
(0.22 to 0.94)
extensor plantar during seizures 4 11 0.36
(0.16 to 0.85) 		4.5
(1.2 to 17)
resisting examination 9 2 4.5
(1.2 to 17) 		0.36
(0.16 to 0.85)
total 13 13

  • Complications in patients with pseudoseizures:
    • respiratory arrest 8/13 (61%: 95% CI: 32% to 91%)
    • infection: 8/13: (54%: 95% CI: 31% to 92%)
  • At follow-up (mean of 23 months (ranged 11 to 54), 9/13 were on anticonvulsants (69%: 95% CI: 34 to 90).

Comments

  1. The study was a case-control study.
  2. Wide confidence intervals due to small numbers in study. Also not a representative sample of patients (pre-selected and retrospective).
  3. A study in Oxford found 86/2500 patients with epilepsy had status (3.4%: 95% CI: 2.7 to 4.2) over ~ 20 years i.e an uncommon disease and difficult to get large numbers to compare with pseudoseizures.

Citation

  1. Howell SJ, Owen L, Chadwick DW: Pseudostatus epilepticus. Quarterly Journal of Medicine 1989; 71 (266): 507-519
Search Terms: reference in review article
Contributor: Chris Ball and Clare Wotton, November 2000
Reviewer:

Clinical Question.
Patient status epilepticus
Intervention or Exposure clinical findings
Outcome pseudoseizures