Objective: To describe a specific dystonic feature associated with corticobasal degeneration(CBD).
Background: Dystonia is common in atypical parkinsonian disorders such as multiple system atrophy, progressive supranuclear palsy and corticobasal degeneration. Clinical recognition of specific dystonic features may assist in the differential diagnosis of atypical parkinsonian disorders and in distinguishing them from Parkinson’s disease (1). Its clinical phenomenology, including body distribution, timing of appearance, and relationship to dopaminergic and other medications may vary considerably within and between atypical parkinsonian disorders.
There had been no systematic analysis of specific types of dystonia occurring in different types of Parkinsonism. One reason for this is that a mixture of different types of dystonia may occur in one individual and most types of Parkinsonian syndromes. There had been no direct correlation of the type of dystonia to pathology or genetics.
Method: This is an observational study. Over a period of 20 years of Neurological practice we have observed a particular pattern of hand dystonia occurring more frequently in CBDS/CBD. Clinical characteristics of this pattern are described below.
Results: Dystonic posture is often unilateral affecting all five digits. No corelation to handedness.
Typically, medial three digits are flexed at proximal interphalangeal joints and to a lesser degree at distal interphalangeal joints. Second digit (Index finger) and thumb are extended. This unique combination of flexion of some and extension of other digits give the impression of pointing a pistol or making hand gesture in which a person uses their hand to mimic a hand gun
We have observed that this specific finger flexion/extension dystonia in the same hand to be associated more commonly in CBD though this pattern is seen infrequently in other types of parkinsonian syndromes. This type of specific dystonia does not occur consistently in CBD but when we noted the pistol sign in a patient with parkinsonian syndrome, majority of the time they fulfilled the criteria for CBD/CBS
Conclusion: In this 20 year observational study we found the pistol sign is a helpful clinical feature when present in identifying patients with CBD. Diagnosis of CBD was undertaken based on published clinical criteria and not pathologically confirmed. Pistol sign is more frequently associated with but not exclusive to CBD.
References: 1
Luca Marsili a, Matteo Bologna b c, Maja Kojovic d, Alfredo Berardelli b c, Alberto
J. Espay a, Carlo Colosimo e
Dystonia in atypical parkinsonian disorders
Parkinsonism & Related Disorders; Volume 66, September 2019, Pages 25-33
To cite this abstract in AMA style:
S H. Wimalaratna. The Pistol Sign [abstract]. Mov Disord. 2023; 38 (suppl 1). https://www.mdsabstracts.org/abstract/the-pistol-sign/. Accessed June 14, 2025.« Back to 2023 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/the-pistol-sign/