Differences in illness perceptions between patients with non-epileptic seizures and functional limb weakness

Illness perceptions play an important role in the onset and maintenance of symptoms in functional neurological symptom disorder (conversion disorder). There has, however, been little work examining differences between subtypes of this disorder. We therefore aimed to compare illness perceptions of patients with non-epileptic seizures (NES) and those with functional weakness (FW) with matching neurological disease controls to examine their specificity.

The Illness Perception Questionnaire Revised (IPQ-R) was completed by patients with functional limb weakness, non-epileptic seizures and patients with neurological disease causing limb weakness and epilepsy in two separate case control studies.

Patients with FW (n=107), NES (=40), Epilepsy (n=34) and neurological disease causing limb weakness (NDLW) (n=46) were included in the analysis. Both FW and NES patients reported a low level of personal control, understanding of their symptoms and a tendency to reject a psychological causation of their symptoms. However NES patients rejected psychological causes less strongly than FW patients (P<.01). Patients with NES were also more likely to consider their treatment to be more effective (P<.01). None of these differences appeared in a similar comparison between patients with epilepsy and patients with NDLW.

Although patients with NES tended, as a group, to reject psychological factors as relevant to their symptoms, they did so less strongly than patients with functional limb weakness in these cohorts. This has implications for both the way in which these symptoms are grouped together but also the way in which treatment is approached.