Pseudodystonia: A new perspective on an old phenomenon

Abstract

Pseudodystonia represents a wide range of conditions that mimic dystonia, including disorders of the peripheral nervous system, spinal cord, brainstem, thalamus, cortex and non-neurological conditions such as musculoskeletal diseases. Here, we propose a definition of pseudodystonia and suggest a classification based on underlying pathophysiological mechanisms. We describe phenomenology of different forms of pseudodystonia and point to distinctions between dystonia and pseudodystonia as well as challenging issues that may arise in clinical practice. The term pseudodystonia can be used to describe abnormal postures, repetitive movements or both, in which results of clinical, imaging, laboratory or electrophysiological investigations provide definite explanation of symptoms which is not compatible with dystonia. Pseudodystonia can be classified into non-neurological disorders of the musculoskeletal system, disorders of sensory pathways, disorders of motor pathways and compensatory postures in other neurological diseases. Presence of associated neurological findings in the affected body part is the key towards diagnosis of pseudodystonia. Additional supporting features are the presence of fixed postures, the absence of sensory trick, acute mode of onset and severe pain. Worsening on eye closure, traditionally considered typical for pseudodystonia, is not always present and can also appear in dystonia. It is challenging to separate dystonia and pseudodystonia in patients with thalamic lesions or corticobasal syndrome, where abnormal postures coexist with sensory loss. Many cases of pseudodystonia are treatable. Therefore, it is essential to consider pseudodystonia in a differential diagnosis of abnormal postures until a detailed neurological examination rules it out.

Syringomyelia Manifesting With Pseudodystonia: A Case Report

“…The clinical features of coexistent motor and sensory abnormalities such as hemiparesis and impaired sensation, an absence of sensory tricks, acute onset and co-occurring severe pain suggested the diagnosis of pseudodystonia rather than true dystonia. 3 Fixed twitching in the left or right limbs occurred regardless of action or a resting state and had no overflow activity, and these findings were inconsistent with true dystonia. 2 Syringomyelia may manifest with abnormal movements, including dystonia, tremor, and athetosis.…”

“…Pseudodystonia may be caused by various neurological diseases that involve the spinal cord or peripheral nervous system but not the brain; alternatively, pseudodystonia may be caused by non-neurological diseases, including arthritis and other musculoskeletal diseases. 2,3 We report a rare case of pseudodystonia caused by syringomyelia.…”

Botulinum neurotoxin in cervical dystonia revisited — recent advances and unanswered questions

“…Pseudodystonias were revisited by Berlot et al in 2019 and new disorders e.g. fibrodysplasia ossificans progressiva have been recognised as possible misdiagnoses [5,37,38].…”

Cervical dystonia — improving the effectiveness of botulinum toxin therapy

“…These related to: turning the head (torticollis), tilting the head to one side (laterocollis), backwards (retrocollis), or forwards (anterocollis). More than 50% of cases were diagnosed as torticollis, 10-15% as laterocollis or retrocollis, and less frequently anterocollis [24]. The 'Col-Cap' concept (collum-caput = neck-head) was invented on the basis of imaging examinations (CT/MRI of the head, cervical spine and also soft tissues) and functional anatomy.…”