MRI evidence of mesial temporal sclerosis in patients with psychogenic nonepileptic seizures.

To the Editor: A number of epidemiologic studies have confirmed the importance of postnatal insults as a cause of epilepsy.1 Neuroimaging has been an increasingly important diagnostic tool, and it has been stated that the demonstration of “epileptogenic lesions” strongly supports the diagnosis of epilepsy in these individuals.2 The article by Benbadis et al. is a timely reminder of the pitfalls of diagnosing epilepsy based on neuroimaging findings alone.3 As the authors stated, EEG remains the standard diagnostic test in these and cases of suspected epilepsy. Whereas many risk factors for psychogenic nonepileptic seizures have been identified,4 isolated psychogenic nonepileptic seizures in patients with CNS lesions have only rarely been reported.5,6 Benbadis et al.’s patients presented with a history of “seizures” and were found to have brain lesions (MTS).3 The opposite situation, namely patients with a CNS lesion who present with stereotypic symptoms that are assumed to represent epilepsy, is an equally difficult and probably a more common dilemma. The diagnosis of epilepsy in these patients, as with the cases reported by Benbadis et al., is frequently based on history and “confirmed” by the demonstration of CNS abnormalities on neuroimaging.3 We recently had four patients with well-defined CNS lesions and “refractory seizures” referred to us for epilepsy surgery in whom appropriate EEG studies showed only psychogenic nonepileptic seizures (table). Psychogenic nonepileptic seizures in the absence of epilepsy have been reported in children with head injuries but have not been well studied in adults with CNS lesions.5 All our patients had clinical manifestations that were “neurologically correct” with the paretic side being the one initially involved at the onset of the psychogenic attacks. In contrast, focal psychogenic neurologic symptoms (paralysis, dysesthesias) in patients without CNS lesions seem to randomly involve either right or left sides of the body.6 None of our patients had epilepsy; all had a positive seizure induction that reproduced their “typical seizures.” Attacks were often but not always precipitated by situations of stress; all patients felt that the residual neurologic deficits limited their ability to cope with life situations. Neuroimaging in each case showed obvious lesions involving cortex and underlying white matter (figure). Telemetry evaluation showed no epileptogenic abnormalities in any of them. However, previous EEG in one postcraniotomy case had been incorrectly interpreted as showing “epileptogenic” abnormalities which in retrospect represented breech rhythms. Whereas patients with psychogenic seizure series are predominantly adults, particularly women, psychogenic seizures and CNS lesions seem to be more common in boys5 and men.