Sensory tricks in pantothenate kinase‐associated neurodegeneration: video‐analysis of 43 patients

Background: Sensory tricks are a classic hallmark of primary dystonia and result in specific maneuvers that temporarily improve dystonic posture or movement. Pantothenate kinase-associated neurodegeneration (PKAN) is a progressive neurological disorder that courses with prominent dystonia. Although previously described, sensory tricks are considered to be rare in PKAN. Cases: We reviewed videotaped motor examinations of 43 genetically confirmed patients with PKAN in order to identify and classify sensory tricks. All patients presented some feature of dystonia. Eighteen (42%) had one or more well-structured sensory tricks. Twelve different sensory tricks were identified, eight typical and four atypical (forcible motor): four in cervical dystonia, four in limb dystonia, three in oromandibular dystonia, and one in blepharospasm. A characteristic forcible motor maneuver for oromandibular dystonia (previously described as the "mantis sign") was present in 8 patients. Conclusions: Sensory tricks are common in PKAN, particularly for oromandibular dystonia. The mantis sign may be a useful clue for the diagnosis.