Clinical differences between patients with psychogenic nonepileptic seizures and functional motor disorder

Why a patient might present with psychogenic nonepileptic seizures (PNES) as opposed to another functional neurological symptom is unknown. A recent review suggested that patients with PNES and functional motor disorders (FMD) differ on demographic and clinical factors of potential aetiological and mechanistic significance, arguing they might represent different disorders, though direct comparisons are limited. We sought to determine whether these factors differed in patients presenting with FMD and PNES at our clinic, as well as whether preceding medical complaints would differ between the two, particularly those affecting the limbs or head.

A retrospective chart review of all presentations with FMD or PNES patients to a functional neurology clinic, collecting demographic and clinical data, including medical and surgical history.

Fifty-six patients with FMD and 52 with PNES were included. Significantly more patients with FMD had functional somatic syndromes (46% vs 27%, p = 0.036) and preceding medical events that affected their limbs than patients with PNES (34% vs 14%, p = 0.013); significantly more patients with PNES had dissociative symptoms (31% vs 4%, p < 0.001) and lifetime suicidal ideation (56% vs 32%, p = 0.013).

These results highlight the substantial comorbidities affecting FMD and PNES, but find clinical differences between the two groups that may be of aetiological or mechanistic significance.