Functional connectivity of dissociation in patients with psychogenic non-epileptic seizures
- Sylvie J M van der Kruijs1,2,
- Nynke M G Bodde1,
- Maarten J Vaessen2,3,
- Richard H C Lazeron1,
- Kristl Vonck4,
- Paul Boon1,4,
- Paul A M Hofman1,2,3,
- Walter H Backes2,3,
- Albert P Aldenkamp1,2,5,
- Jacobus F A Jansen2,3
- 1Epilepsy Centre Kempenhaeghe, Heeze, The Netherlands
- 2School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
- 3Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands
- 4Reference Centre for Refractory Epilepsy, Ghent University Hospital, Ghent, Belgium
- 5Department of Neurology, Maastricht University Medical Centre, Maastricht, The Netherlands
- Correspondence to Dr J F A Jansen, Department of Radiology, Maastricht University Medical Centre, PO Box 5800, 6202 AZ Maastricht, The Netherlands;
Contributors Conception and design, analysis and interpretation of data: SJMvdK, NMGB, MJV, RHCL, WHB, APA and JFAJ. Drafting the article and revising it critically for important intellectual content: SJMvdK, NMGB, RHCL, MJV, WHB, APA and JFAJ. Final approval of the version to be published: SJMvdK, NMGB, MJV, RHCL, KV, PB, PAMH, WHB, APA and JFAJ.
- Received 19 June 2011
- Revised 12 September 2011
- Accepted 17 September 2011
- Published Online First 5 November 2011
Introduction Psychogenic non-epileptic seizures (PNES) resemble epileptic seizures, but lack epileptiform brain activity. Instead, the cause is assumed to be psychogenic. An abnormal coping strategy may be exhibited by PNES patients, as indicated by their increased tendency to dissociate. Investigation of resting-state networks may reveal altered routes of information and emotion processing in PNES patients. The authors therefore investigated whether PNES patients differ from healthy controls in their resting-state functional connectivity characteristics and whether these connections are associated with the tendency to dissociate.
Methods 11 PNES patients without psychiatric comorbidity and 12 healthy controls underwent task-related paradigms (picture-encoding and Stroop paradigms) and resting-state functional MRI (rsfMRI). Global cognitive performance was tested using the Raven's Matrices test and participants completed questionnaires for evaluating dissociation. Functional connectivity analysis on rsfMRI was based on seed regions extracted from task-related fMRI activation maps.
Results The patients displayed a significantly lower cognitive performance and significantly higher dissociation scores. No significant differences were found between the picture-encoding and Stroop colour-naming activation maps between controls and patients with PNES. However, functional connectivity maps from the rsfMRI were statistically different. For PNES patients, stronger connectivity values between areas involved in emotion (insula), executive control (inferior frontal gyrus and parietal cortex) and movement (precentral sulcus) were observed, which were significantly associated with dissociation scores.
Conclusion The abnormal, strong functional connectivity in PNES patients provides a neurophysiological correlate for the underlying psychoform and somatoform dissociation mechanism where emotion can influence executive control, resulting in altered motor function (eg, seizure-like episodes).
- Psychogenic non-epileptic seizures
- functional MRI
- functional connectivity
- executive control, neuropsychology
- clinical neurology
- electrical stimulation
- functional imaging
- cognitive neuropsychology
- head injury
- motor neuron disease
Funding JFAJ was funded by VENI research grant 916.11.059 from The Netherlands Organization for Scientific Research (NWO) and The Netherlands Organization for Health Research and Development (ZonMw). APA is supported by the National Epilepsy Foundation (NEF), Zeist, the Netherlands.
Competing interests None.
Patient consent Obtained.
Ethics approval Medical Ethical Committee of Maastricht University (ref. 10-3-045).
Provenance and peer review Not commissioned; externally peer reviewed.