Tremulous cervical dystonia is likely to be familial: clinical characteristics of a large cohort

Isolated Cervical Dystonia: Diagnosis and Classification

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.

Early-onset inherited dystonias versus late-onset idiopathic dystonias: Same or different biological mechanisms?

Dystonia syndromes encompass a heterogeneous group of movement disorders which might be differentiated by several clinical-historical features. Among the latter, age-at-onset is probably the most important in predicting the likelihood both for the symptoms to spread from focal to generalized and for a genetic cause to be found. Accordingly, dystonia syndromes are generally stratified into early-onset and late-onset forms, the former having a greater likelihood of being monogenic disorders and the latter to be possibly multifactorial diseases, despite being currently labeled as idiopathic. Nonetheless, there are several similarities between these two groups of dystonia, including shared pathophysiological and biological mechanisms. Moreover, there is also initial evidence of age-related modifiers of early-onset dystonia syndromes and of critical periods of vulnerability of the sensorimotor network, during which a combination of genetic and non-genetic insults is more likely to produce symptoms. Based on these lines of evidence, we reappraise the double-hit hypothesis of dystonia, which would accommodate both similarities and differences between early-onset and late-onset dystonia in a single framework.

Tremor is associated with familial clustering of dystonia

INTRODUCTION

Dystonia is a movement disorder of variable etiology and clinical presentation and is accompanied by tremor in about 50% of cases. Monogenic causes in dystonia are rare, but also in the group of non-monogenic dystonias 10-30% of patients report a family history of dystonia. This points to a number of patients currently classified as idiopathic that have at least in part an underlying genetic contribution. The present study aims to identify clinical and demographic features associated with heritability of yet idiopathic dystonia.

METHODS

Seven hundred thirty-three datasets were obtained from the DysTract dystonia registry, patients with acquired dystonia or monogenic causes were excluded. Affected individuals were assigned to a familial and sporadic group, and clinical features were compared across these groups. Additionally, the history of movement disorders was also counted in family members.

RESULTS

18.2% of patients reported a family history of dystonia. Groups differed in age at onset, disease duration and presence of tremor on a descriptive level. Logistic regression analysis revealed that tremor was the only predictor for a positive family history of dystonia (OR 2.49, CI = 1.54-4.11, p < 0.001). Tremor turned out to be the most common movement disorder in available relatives of patients, and presence of tremor in relatives was associated with tremor in index patients (X²(1) = 16.2, p < 0.001).

CONCLUSIONS

Tremor is associated with an increased risk of familial clustering of dystonia and with a family history of tremor itself. This indicates a hereditable dystonia-tremor syndrome with a clinical spectrum ranging from tremor-predominant diseases to dystonia.

Functional and Idiopathic Cervical Dystonia in Two Family Members: A Challenging Diagnosis

Background:

Cervical dystonia (CD) often occurs in the same family.

Case report:

A 40-year-old woman presented with a longstanding history of CD and signs of inconsistency at history taking and neurological examination; her 65-year-old mother was diagnosed instead with idiopathic CD, which had begun 7 years after the onset of CD in her daughter.

Discussion:

Idiopathic and functional CD share common clinical and endophenotypic traits, making the differential diagnosis particularly challenging. A complete examination is warranted.

The Effect of Escitalopram on Central Serotonergic and Dopaminergic Systems in Patients with Cervical Dystonia, and Its Relationship with Clinical Treatment Effects: A Double-Blind Placebo-Controlled Trial

Purpose: The pathophysiology of cervical dystonia (CD) is thought to be related to changes in dopamine and serotonin levels in the brain. We performed a double-blind trial with escitalopram (selective serotonin reuptake inhibitor; SSRI) in patients with CD. Here, we report on changes in dopamine D_2/3 receptor (D2/3R), dopamine transporter (DAT) and serotonin transporter (SERT) binding potential (BP_ND) after a six-week treatment course with escitalopram or placebo. Methods: CD patients had [123I]FP-CIT SPECT (I-123 fluoropropyl carbomethoxy-3 beta-(4-iodophenyltropane) single-photon emission computed tomography) scans, to quantify extrastriatal SERT and striatal DAT, and [123I]IBZM SPECT (I-123 iodobenzamide SPECT) scans to quantify striatal D2/3R BPND before and after six weeks of treatment with either escitalopram or placebo. Treatment effect was evaluated with the Clinical Global Impression scale for dystonia, jerks and psychiatric symptoms, both by physicians and patients. Results: In both patients treated with escitalopram and placebo there were no significant differences after treatment in SERT, DAT or D2/3R BP_ND. Comparing scans after treatment with escitalopram (n = 8) to placebo (n = 8) showed a trend (p = 0.13) towards lower extrastriatal SERT BPND in the SSRI group (median SERT occupancy of 64.6%). After treatment with escitalopram, patients who reported a positive effect on dystonia or psychiatric symptoms had significantly higher SERT occupancy compared to patients who did not experience an effect. Conclusion: Higher extrastriatal SERT occupancy after treatment with escitalopram is associated with a trend towards a positive subjective effect on dystonia and psychiatric symptoms in CD patients.

Longitudinal follow-up with VIM thalamic deep brain stimulation for dystonic or essential tremor

OBJECTIVE

To assess longitudinal tremor outcomes with ventral intermediate nucleus deep brain stimulation (VIM DBS) in patients with dystonic tremor (DT) and to compare with DBS outcomes in essential tremor (ET).

METHODS

We retrospectively investigated VIM DBS outcomes for 163 patients followed at our center diagnosed with either DT or ET. The Fahn-Tolosa-Marin tremor rating scale (TRS) was used to assess change in tremor and activities of daily living (ADL) at 6 months, 1 year, 2-3 years, 4-5 years, and ≥6 years after surgery.

RESULTS

Twenty-six patients with DT and 97 patients with ET were analyzed. Compared to preoperative baseline, there were significant improvements in TRS motor up to 4-5 years (52.2%; p = 0.032) but this did not reach statistical significance at ≥6 years (46.0%, p = 0.063) in DT, which was comparable to the outcomes in ET. While the improvements in the upper extremity tremor, head tremor, and axial tremor were also comparable between DT and ET throughout the follow-up, the ADL improvements in DT were lost at 2-3 years follow-up.

CONCLUSION

Overall, tremor control with VIM DBS in DT and ET was comparable and remained sustained at long term likely related to intervention at the final common node in the pathologic tremor network. However, the long-term ADL improvements in DT were not sustained, possibly due to inadequate control of concomitant dystonia symptoms. These findings from a large cohort of DT indicate that VIM targeting is reasonable if the tremor is considerably more disabling than the dystonic features.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that VIM DBS improves tremor in patients with DT or ET.

The Prevalence of Dystonic Tremor and Tremor Associated with Dystonia in Patients with Cervical Dystonia

The link between dystonia and tremor has been known for decades, but the question of whether they are two separate illnesses or just different manifestations of one disease with the same pathophysiological background remains unanswered. We distinguish two types of tremor in dystonia: dystonic tremor (DT), which appears on the body part affected by dystonia, and tremor associated with dystonia (TAWD), which appears in locations where the dystonia does not occur. In this study, the frequency of occurrence of different forms of tremor was determined by clinical examination in a group of adult-onset isolated cervical dystonia (CD) patients treated with regular local injections of botulinum toxin A in our department. In total, 120 patients were included in the study, of which 70 (58.3%) had DT of the head. TAWD was, in all 14 cases (11.7%), observed on the upper limbs, in the form of static or intentional tremor. The aim of this study was to point out the presence of TAWD as one of the clinical signs of CD. DT occurred in more than half of the patients and appears to be a relatively common part of the clinical picture in patients with CD.

Dystonia

Dystonia is a neurological condition characterized by abnormal involuntary movements or postures owing to sustained or intermittent muscle contractions. Dystonia can be the manifesting neurological sign of many disorders, either in isolation (isolated dystonia) or with additional signs (combined dystonia). The main focus of this Primer is forms of isolated dystonia of idiopathic or genetic aetiology. These disorders differ in manifestations and severity but can affect all age groups and lead to substantial disability and impaired quality of life. The discovery of genes underlying the mendelian forms of isolated or combined dystonia has led to a better understanding of its pathophysiology. In some of the most common genetic dystonias, such as those caused by TOR1A, THAP1, GCH1 and KMT2B mutations, and idiopathic dystonia, these mechanisms include abnormalities in transcriptional regulation, striatal dopaminergic signalling and synaptic plasticity and a loss of inhibition at neuronal circuits. The diagnosis of dystonia is largely based on clinical signs, and the diagnosis and aetiological definition of this disorder remain a challenge. Effective symptomatic treatments with pharmacological therapy (anticholinergics), intramuscular botulinum toxin injection and deep brain stimulation are available; however, future research will hopefully lead to reliable biomarkers, better treatments and cure of this disorder.

Randomised controlled trial of escitalopram for cervical dystonia with dystonic jerks/tremor

OBJECTIVE

Trials for additional or alternative treatments for cervical dystonia (CD) are scarce since the introduction of botulinum neurotoxin (BoNT). We performed the first trial to investigate whether dystonic jerks/tremor in patients with CD respond to the selective serotonin reuptake inhibitor (SSRI) escitalopram.

METHODS

In a randomised, double-blind, crossover trial, patients with CD received escitalopram and placebo for 6 weeks. Treatment with BoNT was continued, and scores on rating scales regarding dystonia, psychiatric symptoms and quality of life (QoL) were compared. Primary endpoint was the proportion of patients that improved at least one point on the Clinical Global Impression Scale for jerks/tremor scored by independent physicians with experience in movement disorders.

RESULTS

Fifty-threepatients were included. In the escitalopram period, 14/49 patients (29%) improved on severity of jerks/tremor versus 11/48 patients (23%) in the placebo period (P=0.77). There were no significant differences between baseline and after treatment with escitalopram or placebo on severity of dystonia or jerks/tremor. Psychiatric symptoms and QoL improved significantly in both periods compared with baseline. There were no significant differences between treatment with escitalopram and placebo for dystonia, psychiatric or QoL rating scales. During treatment with escitalopram, patients experienced slightly more adverse events, but no serious adverse events occurred.

CONCLUSION

In this innovative trial, no add-on effect of escitalopram for treatment of CD with jerks was found on motor or psychiatric symptoms. However, we also did not find a reason to withhold patients treatment with SSRIs for depression and anxiety, which are common in dystonia.

TRIAL REGISTRATION NUMBER

NTR2178.

Lower serotonin transporter binding in patients with cervical dystonia is associated with psychiatric symptoms

BACKGROUND

Cervical dystonia (CD) is often accompanied by depressive symptoms, anxiety, and jerks/tremor. The dopamine transporter (DAT) binding is related with both depressive symptoms and jerks/tremor in CD. Serotonergic and dopaminergic systems are closely related. As serotonin is involved in the pathophysiology of psychiatric symptoms and jerks, we expected an altered serotoninergic system in CD. We hypothesized that CD is associated with reduced serotonin transporter (SERT) binding, more specific that SERT binding is lower in CD patients with psychiatric symptoms and/or jerks/tremor compared to those without, and to controls. The balance between SERT and DAT binding can be altered in different CD phenotypes.

RESULTS

In 23 CD patients and 14 healthy controls, SERT binding in the diencephalon/midbrain was assessed using [¹²³I]FP-CIT SPECT, with a brain-dedicated system. The specific to non-specific binding ratio (binding potential; BP_ND) to SERT was the main outcome measure. There was a clear trend towards reduced SERT BP_ND in CD patients with psychiatric symptoms compared to those without (p = 0.05). There was no correlation between SERT binding and dystonia, jerks, or anxiety. There was a significant positive correlation between extrastriatal SERT and striatal DAT BP_ND in CD patients with jerks, but not in patients without jerks.

CONCLUSION

CD patients with psychiatric symptoms have lower SERT binding in the midbrain/diencephalon, while dystonia and jerks appear unrelated to SERT binding. The balance between extrastriatal SERT and striatal DAT binding is different in CD with and without jerks.

Tremor in Dystonia: A Cross-sectional Study from India

Background

Tremor is an important phenotypic motor feature in dystonia, but there is limited literature regarding its prevalence and phenomenology.

Methods

This cross-sectional study included 90 patients with adult-onset, isolated dystonia from a tertiary care movement disorder center in India. Patients were assessed for tremor in the head and in different body parts. Surface electromyography studies of tremor were recorded of the involved limb in different positions.

Results

Tremor was present in 41 patients (45.55%) who had dystonia, including 21 of 41 patients (51.21%) with cervical dystonia, 15 of 34 (44.11%) with limb dystonia, and 5 of 15 (33.33%) with cranial dystonia. Significantly later age at presentation (47.19 ± 14.55 years vs. 40.39 ± 13.74 years; P = 0.012) and longer disease duration (5.11 ± 5.85 years vs. 2.60 ± 2.57 years; P = 0.004) were observed in patients with versus without tremor. Upper limb tremor was present in 33 patients, head tremor was present in 14, and leg tremor was present in 2. Tremor was present in 17 of 25 patients (68%) with segmental dystonia and in 6 of 9 (66.66%) with multifocal dystonia. Tremor was least frequent in patients with focal dystonia (18 of 56 patients; 32.14%).

Conclusions

Tremor was common (>45%) in patients with primary adult-onset dystonia. Patients who had tremor were older and had a longer duration of symptoms. Patients with segmental and multifocal dystonia had more tremor than those with focal dystonia. In contrast to some other studies, the current patients had more upper limb tremor than head tremor, and a combination of dystonic tremor and tremor associated with dystonia was more common than isolated dystonic tremor.

The relationship between the dopaminergic system and depressive symptoms in cervical dystonia

PURPOSE

Cervical dystonia (CD) is associated with tremor/jerks (50%) and psychiatric complaints (17-70%). The dopaminergic system has been implicated in the pathophysiology of CD in animal and imaging studies. Dopamine may be related to the motor as well as non-motor symptoms of CD. CD is associated with reduced striatal dopamine D_2/3 (D2/3) receptor and increased dopamine transporter (DAT) binding. There are differences in the dopamine system between CD patients with and without jerks/tremor and psychiatric symptoms.

METHODS

Patients with CD and healthy controls underwent neurological and psychiatric examinations. Striatal DAT and D2/3 receptor binding were assessed using [¹²³I]FP-CIT and [¹²³I]IBZM SPECT, respectively. The ratio of specific striatal to non-specific binding (binding potential; BP_ND) was the outcome measure.

RESULTS

Twenty-seven patients with CD and 15 matched controls were included. Nineteen percent of patients fulfilled the criteria for a depression. Striatal DAT BP_ND was significantly lower in depressed versus non-depressed CD patients. Higher DAT BP_ND correlated significantly with higher scores on the Unified Myoclonus Rating Scale (UMRS). The striatal D2/3 receptor BP_ND in CD patients showed a trend towards lower binding compared to controls. The D2/3 BP_ND was significantly lower in depressed versus non-depressed CD patients. A significant correlation between DAT and D2/3R BP_ND was found in both in patients and controls.

CONCLUSIONS

Alterations of striatal DAT and D2/3 receptor binding in CD patients are related mainly to depression. DAT BP_ND correlates significantly with scores on the UMRS, suggesting a role for dopamine in the pathophysiology of tremor/jerks in CD.

Clinical and demographic characteristics related to onset site and spread of cervical dystonia

BACKGROUND

Clinical characteristics of isolated idiopathic cervical dystonia such as onset site and spread to and from additional body regions have been addressed in single-site studies with limited data and incomplete or variable dissociation of focal and segmental subtypes. The objectives of this study were to characterize the clinical characteristics and demographics of isolated idiopathic cervical dystonia in the largest standardized multicenter cohort.

METHODS

The Dystonia Coalition, through a consortium of 37 recruiting sites in North America, Europe, and Australia, recruited 1477 participants with focal (60.7%) or segmental (39.3%) cervical dystonia on examination. Clinical and demographic characteristics were evaluated in terms of the body region of dystonia onset and spread.

RESULTS

Site of dystonia onset was: (1) focal neck only (78.5%), (2) focal onset elsewhere with later segmental spread to neck (13.3%), and (3) segmental onset with initial neck involvement (8.2%). Frequency of spread from focal cervical to segmental dystonia (22.8%) was consistent with prior reports, but frequency of segmental onset with initial neck involvement was substantially higher than the 3% previously reported. Cervical dystonia with focal neck onset, more than other subtypes, was associated with spread and tremor of any type. Sensory tricks were less frequent in cervical dystonia with segmental components, and segmental cervical onset occurred at an older age.

CONCLUSIONS

Subgroups had modest but significant differences in the clinical characteristics that may represent different clinical entities or pathophysiologic subtypes. These findings are critical for design and implementation of studies to describe, treat, or modify disease progression in idiopathic isolated cervical dystonia. © 2016 International Parkinson and Movement Disorder Society.

Tremor entities and their classification: an update

PURPOSE OF REVIEW

This review focuses on important new findings in the field of tremor and illustrates the consequences for the current definition and classification of tremor.

RECENT FINDINGS

Since 1998 when the consensus criteria for tremor were proposed, new variants of tremors and new diagnostic methods were discovered that have changed particularly the concepts of essential tremor and dystonic tremor. Accumulating evidence exists that essential tremor is not a single entity rather different conditions that share the common symptom action tremor without other major abnormalities. Tremor is a common feature in patients with adult-onset focal dystonia and may involve several different body parts and forms of tremor. Recent advances, in particular, in the field of genetics, suggest that dystonic tremor may even be present without overt dystonia. Monosymptomatic asymmetric rest and postural tremor has been further delineated, and apart from tremor-dominant Parkinson's disease, there are several rare conditions including rest and action tremor with normal dopamine transporter imaging (scans without evidence of dopaminergic deficit) and essential tremor with tremor at rest.

SUMMARY

Increasing knowledge in the last decades changed the view on tremors and highlights several caveats in the current tremor classification. Given the ambiguous assignment between tremor phenomenology and tremor etiology, a more cautious definition of tremors on the basis of clinical assessment data is needed.

Dystonia and Tremor: The Clinical Syndromes with Isolated Tremor

BACKGROUND

Dystonia and tremor share many commonalities. Isolated tremor is part of the phenomenological spectrum of isolated dystonia and of essential tremor. The occurrence of subtle features of dystonia may allow one to differentiate dystonic tremor from essential tremor. Diagnostic uncertainty is enhanced when no features of dystonia are found in patients with a tremor syndrome, raising the question whether the observed phenomenology is an incomplete form of dystonia.

METHODS

Known forms of syndromes with isolated tremor are reviewed. Diagnostic uncertainties between tremor and dystonia are put into perspective.

RESULTS

The following isolated tremor syndromes are reviewed: essential tremor, head tremor, voice tremor, jaw tremor, and upper-limb tremor. Their varied phenomenology is analyzed and appraised in the light of a possible relationship with dystonia.

DISCUSSION

Clinicians making a diagnosis of isolated tremor should remain vigilant for the detection of features of dystonia. This is in keeping with the recent view that isolated tremor may be an incomplete phenomenology of dystonia.

Rest and other types of tremor in adult-onset primary dystonia

INTRODUCTION

Knowledge regarding tremor prevalence and phenomenology in patients with adult-onset primary dystonia is limited. Dystonic tremor is presumably under-reported, and we aimed to assess the prevalence and the clinical correlates of tremor in patients with adult-onset primary dystonia.

METHODS

We enrolled 473 consecutive patients with different types of adult-onset primary dystonia. They were assessed for presence of head tremor and arm tremor (rest, postural and kinetic).

RESULTS

A total of 262 patients (55.4%) were tremulous: 196 patients presented head tremor, 140 patients presented arm tremor and 98 of them had a combination of head and arm tremor. Of the 140 patients with arm tremor, all presented postural tremor, 103 patients (73.6%) presented also a kinetic component, whereas 57 patients (40.7%) had rest tremor. Rest tremor was unilateral/asymmetric in up to 92.9% of them. Patients with segmental and multifocal dystonia were more likely tremulous than patients with focal dystonia. Dystonic symptoms involving the neck were more frequently observed in patients with head tremor, whereas dystonic symptoms involving the arms were more frequently observed in patients with arm tremor.

DISCUSSION

Here we show that tremor is a common feature of patients with adult-onset primary dystonia. It may involve different body segments, with the head being the most commonly affected site. Arm tremor is also frequent (postural>kinetic>rest), occurring in up to one-third of cases. There is a suggestion of a stronger tendency for spread of dystonic features in patients with associated tremor. Dystonic tremor is under-reported and this underscores the importance of careful clinical examination when assessing tremulous patients without overt dystonia.

The phenotypic spectrum of DYT24 due to ANO3 mutations

Genes causing primary dystonia are rare. Recently, pathogenic mutations in the anoctamin 3 gene (ANO3) have been identified to cause autosomal dominant craniocervical dystonia and have been assigned to the dystonia locus dystonia-24 (DYT24). Here, we expand on the phenotypic spectrum of DYT24 and provide demonstrative videos. Moreover, tremor recordings were performed, and back-averaged electroencephalography, sensory evoked potentials, and C-reflex studies were carried out in two individuals who carried two different mutations in ANO3. Ten patients from three families are described. The age at onset ranged from early childhood to the forties. Cervical dystonia was the most common site of onset followed by laryngeal dystonia. The characteristic feature in all affected individuals was the presence of tremor, which contrasts DYT24 from the typical DYT6 phenotype. Tremor was the sole initial manifestation in some individuals with ANO3 mutations, leading to misdiagnosis as essential tremor. Electrophysiology in two patients with two different mutations showed co-contraction of antagonist muscles, confirming dystonia, and a 6-Hz arm tremor at rest, which increased in amplitude during action. In one of the studied patients, clinically superimposed myoclonus was observed. The duration of the myoclonus was in the range of 250 msec at about 3 Hz, which is more consistent with subcortical myoclonus. In summary, ANO3 causes a varied phenotype of young-onset or adult-onset craniocervical dystonia with tremor and/or myoclonic jerks. Patients with familial cervical dystonia who also have myoclonus-dystonia as well as patients with prominent tremor and mild dystonia should be tested for ANO3 mutations. © 2014 The Authors. Movement Disorders published by International Parkinson and Movement Disorder Society

Rest and other types of tremor in adult-onset primary dystonia

INTRODUCTION

Knowledge regarding tremor prevalence and phenomenology in patients with adult-onset primary dystonia is limited. Dystonic tremor is presumably under-reported, and we aimed to assess the prevalence and the clinical correlates of tremor in patients with adult-onset primary dystonia.

METHODS

We enrolled 473 consecutive patients with different types of adult-onset primary dystonia. They were assessed for presence of head tremor and arm tremor (rest, postural and kinetic).

RESULTS

A total of 262 patients (55.4%) were tremulous: 196 patients presented head tremor, 140 patients presented arm tremor and 98 of them had a combination of head and arm tremor. Of the 140 patients with arm tremor, all presented postural tremor, 103 patients (73.6%) presented also a kinetic component, whereas 57 patients (40.7%) had rest tremor. Rest tremor was unilateral/asymmetric in up to 92.9% of them. Patients with segmental and multifocal dystonia were more likely tremulous than patients with focal dystonia. Dystonic symptoms involving the neck were more frequently observed in patients with head tremor, whereas dystonic symptoms involving the arms were more frequently observed in patients with arm tremor.

DISCUSSION

Here we show that tremor is a common feature of patients with adult-onset primary dystonia. It may involve different body segments, with the head being the most commonly affected site. Arm tremor is also frequent (postural>kinetic>rest), occurring in up to one-third of cases. There is a suggestion of a stronger tendency for spread of dystonic features in patients with associated tremor. Dystonic tremor is under-reported and this underscores the importance of careful clinical examination when assessing tremulous patients without overt dystonia.