Isolated Cervical Dystonia: Diagnosis and Classification

Abstract

This document presents a consensus on the diagnosis and classification of isolated cervical dystonia (iCD) with a review of proposed terminology. The International Parkinson and Movement Disorder Society Dystonia Study Group convened a panel of experts to review the main clinical and diagnostic issues related to iCD and to arrive at a consensus on diagnostic criteria and classification. These criteria are intended for use in clinical research, but also may be used to guide clinical practice. The benchmark is expert clinical observation and evaluation. The criteria aim to systematize the use of terminology as well as the diagnostic process, to make it reproducible across centers and applicable by expert and non‐expert clinicians. Although motor abnormalities remain central, increasing recognition has been given to nonmotor manifestations, which are incorporated into the current criteria. Three iCD presentations are described in some detail: idiopathic (focal or segmental) iCD, genetic iCD, and acquired iCD. The relationship between iCD and isolated head tremor is also reviewed. Recognition of idiopathic iCD has two levels of certainty, definite or probable, supported by specific diagnostic criteria. Although a probable diagnosis is appropriate for clinical practice, a higher diagnostic level may be required for specific research studies. The consensus retains elements proven valuable in previous criteria and omits aspects that are no longer justified, thereby encapsulating diagnosis according to current knowledge. As understanding of iCD expands, these criteria will need continuous revision to accommodate new advances. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Therapeutic Benefit of Sensory Trick in Cervical Dystonia

“…Unlike the Dystonia Coalition database, 17 the CD PROBE registry 9 protocol with data collected from 2009 to 2012 did not require data to be collected on involvement of body regions beyond head and neck or on presence of other phenomenology. This limits our ability to classify subjects in the CD PROBE registry using 2023 criteria 4 . It is possible that a poor response to sensory trick could be because those subjects did not have idiopathic isolated CD.…”

“…Sensory tricks are thought to be most effective early on in the disease course and may completely alleviate posturing and associated disability in some individuals 2,3 . Their importance in CD is demonstrated by their inclusion as a supportive diagnostic criterion 4 . Imaging and neurophysiology studies suggest that sensory tricks act via modulation of the abnormal network by peripheral sensory feedback, in particular by involvement of the sensorimotor cortex 5 .…”

“…2,3 Their importance in CD is demonstrated by their inclusion as a supportive diagnostic criterion. 4 Imaging and neurophysiology studies suggest that sensory tricks act via modulation of the abnormal network by peripheral sensory feedback, in particular by involvement of the sensorimotor cortex. 5 A study using functional MRI showed increased functional connectivity of sensorimotor network in CD subjects without a sensory trick, while an effective sensory trick was associated with a decrease in connectivity in the same network.…”

New developments in diagnostics and treatment of adult-onset focal dystonia

“…This study provides a recommendation for cervical dystonia, in which is proposed to reserve the diagnosis of focal cervical dystonia for those patients in which only muscles that move the neck are involved [6 ▪ ] (Table 1). Recently, the MDS has published a consensus statement regarding the classification of idiopathic cervical dystonia, differentiating between the two levels ‘definite’ and ‘probably’ idiopathic cervical dystonia [8 ▪▪ ]. Supportive criteria and exclusion criteria for cervical dystonia diagnosis were identified (Tables 2 and 3).…”

“…Supportive criteria and exclusion criteria for cervical dystonia diagnosis were identified (Tables 2 and 3). Additionally, required criteria are also provided for diagnosis of genetic and acquired cervical dystonia [8 ▪▪ ].…”