Sensory Tricks in Pantothenate Kinase-Associated Neurodegeneration: Video-Analysis of 43 Patients

Abstract

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.

Keywords: PKAN; alleviating maneuvers; secondary dystonia; sensory tricks.

Figure 1

Sensory tricks in PKAN: touching specific parts of the face (A,F), mantis sign (B–E), using an object (G), headband (H,I), wings posture (J), lobster pincers (K), self‐hug (L), placing contralateral arm above the forearm (M), and complex tricks (N,O).