Abstracts

Patients with objective evidence of epileptic seizures (ES) are often difficult to separate from those with psychogenic nonepileptic seizures (PNES) on the basis of neurocognitive testing. This difficulty has been attributed to subtle neurological damage or diminished ability to handle emotional stress (Wilkus, Dodrill, [amp] Thompson, 1984; Binder et al., 1998). Green and colleagues (2001) recently demonstrated that effort, as quantified by modern symptom validity testing, often explains more variance in neurocognitive test performance than does the presence of the neurocognitive disorder itself. To date, only one group has studied the effects of effort on testing in patients with ES and PNES (Binder et al., 1998), but these studies were done with tests that may be less sensitive than more recently validated tests. This study is meant to re-examine the role that objectively-quantified effort plays in mediating performance of these groups on neurocognitive testing.
Fifty-seven patients consecutively referred for continuous video-EEG monitoring for evaluation of apparent uncontrolled seizures at the University of Washington were administered the Word Memory Test as part of a comprehensive epilepsy neuropsychological evaluation. Patients were classified on the basis of their ictal EEG recordings and behavioral presentation as experiencing ES (n=32; evidence of definite EEG abnormalities), PNES (n=14; episodes of unresponsiveness or behavioral abnormality in the absence of EEG changes), nonepileptic spells of other origin (NESO: n=5; spells related to other causes, such as syncope), or indeterminate spells (IS: n=6; no spells during monitoring or subjective feelings only, in the absence of EEG abnormality and without unresponsiveness or behavioral abnormality).
The majority (64%) of PNES patients [quot]failed[quot] symptom validity testing. In marked contrast, the ES and indeterminate groups failed such tests at rates of 13% for ES, 17% for IS, and 0% for NESO. These differences are far greater than those expected by chance (p [lt] .001) and far exceed the rates of symptom validity failures reported in other studies using older techniques.
For the majority of PNES patients in this sample, behavioral or emotional difficulties are more likely to explain neurocognitive test performance than actual neurocognitive deficits. These results strongly suggest that newer tests of symptom validity should be employed in neuropsychological evaluations of patients with apparent uncontrolled seizures. Further exploration of these results may assist in the psychometric differentiation of patients with PNES from patients with ES. Moreover, we should gain a better understanding of the extent to which the difficulty differentiating these groups may be a function of effort rather than the hypothesized occult neuropathology reported in the histories of patients with PNES.