Characteristic "Forcible" Geste Antagoniste in Oromandibular Dystonia Resulting From Pantothenate Kinase-Associated Neurodegeneration.

Geste antagonistes are usually considered typical of primary dystonia, although rarely they have been described in secondary/heredodegenerative dystonias. We have recently come across a particular geste antagoniste in 5 of 10 patients with pantothenate kinase-associated neurodegeneration (PKAN) who had prominent oromandibular involvement with severe jaw-opening dystonia. It consists of touching the chin with both hands characteristically clenched into a fist with flexion at the elbows. Because of the resemblance of this geste antagoniste with the praying-like posture of Mantis religiosa, we coined the term "mantis sign." Reviewing videos of PKAN cases in literature, including what is considered the first cinematic depiction of a case of this disorder, 3 additional cases with akin maneuvers were identified. In contrast, examining 205 videos of non-PKAN dystonic patients from our database for the presence of a similar maneuver was unrevealing. Thus, we consider the mantis sign to be quite typical of PKAN and propose it to be added as a clinical hint toward diagnosis.