Cervical Dystonia Research Articles

Conversion to AbobotulinumtoxinA Increases Waning Time and Efficacy for Cervical Dystonia.

Symptom re-emergence before re-injection negatively impacts cervical dystonia (CD) patients receiving botulinum toxin type A (BoNT-A) therapy. Longer waning time is associated with abobotulinumtoxinA (abo-BoNT-A) as compared to onabotulinumtoxinA (ona-BoNT-A)/incobotulinumtoxinA (inco-BoNT-A) formulations. To compare waning time and treatment outcomes when chronically injected CD patients experiencing early waning despite being optimized on BoNT-A (ona-BoNT-A/inco-BoNT-A) were converted to abo-BoNT-A. Thirty-three chronically injected CD participants with a waning time of ≤8 weeks were converted to abo-BoNT-A (1:2.5 dose ratio) for three injections every 12-weeks. The second and third injection patterns were kinematically optimized. Participants were converted back to their original BoNT-A for the fourth injection (1:2.5) using the same third abo-BoNT-A pattern. Participant-perceived waning times were collected post-injections. Clinical scales (Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS)) and kinematic measures were collected 12-weeks post-injection and at three peak effect time-points. Compared to baseline, waning time (12-22 days) significantly increased following all abo-BoNT-A treatments (P < 0.005) but was not significantly different at the fourth injection (original BoNT-A reconversion). TWSTRS sub-scores significantly reduced following all abo-BoNT-A treatments (P < 0.0001) and at peak effect following the third injection compared to original BoNT-A. Dysphagia and muscle weakness were reported and comparable to safety of original BoNT-A formulations. Optimized patients experiencing waning had significant improvement in the peak benefit as well as the duration of effect when converted to abo-BoNT-A. This effect was toxin dependent as reconversion to the original BoNT-A using the kinematically optimized pattern failed to produce an improvement in waning.

Effects of Functional Electrical Stimulation with and without Kinesiotherapy on Pain, Range of Motion and Quality of Life in Patients with Cervical Dystonia; A Randomized Clinical Trial

Methods: This study was a Randomized Controlled Trial conducted at The University of Lahore Teaching Hospital, University Institute of Physical Therapy, Lahore. n= 84 patients with Cervical Dystonia were recruited in this study using non- probability convenient sampling technique. Patients suffering with Cervical Dystonia who aged between 30 till 50 years were randomly assigned into two groups, 42 patients in each group. First Group A which was the control group which was treated with Functional Electrical Stimulation and routine physical therapy only while Group B was the Experimental group which was treated with Functional Electrical Stimulation also with kinesiotherapy and routine physical therapy. Both the groups were evaluated and assessed using the Toronto Western Spasmodic Torticollis Rating Scale, the Pain Numerating Scale, the 36- item short form health survey( SF-36), Neck Disability index and range of motion of neck flexion, neck extension and neck rotation was measured using universal goniometer. Results: Functional Electrical Stimulation combined with kinesiotherapy given to the experimental group showed more improvement in range of motion, quality of life , functional disability and the symptom of the pain also was reduced in the experimental group as compared to the control group. The mean values showed that there was a statistically significant difference in different variables between both the groups. When the scores( scores at baseline and at 16th week) for Toronto Western Spasmodic Torticollis Rating Scale for both the groups were compared it showed statistical difference between both the groups(p&lt;0.05). Conclusion: Despite the fact that cervical dystonia has central neurological etiology, this study concludes that multimodal kinesiotherapy program which included stretching and relaxation, active exercises in addition to Functional Electrical Stimulation and Routine Physical Therapy tempts to have beneficial effects on a patient suffering from Cervical Dystonia. It showed beneficial effects on pain, quality of life, functional disability and range of motion of patients with cervical dystonia. Key Words: Functional Electrical Stimulation, Kinesiotherapy, Cervical Dystonia, Pain, Rang of Motion, Quality of life

Identifying safety zone of invasive procedures in the sternocleidomastoid muscle using ultrasonography.

Dysfunctions of the sternocleidomastoid (SCM) muscle, such as myofascial syndrome, torticollis, and cervical dystonia, have been treated using several invasive procedures. In such situations, it is possible to injure the adjacent nerves. This study aimed to demonstrate the course of these nerves in healthy volunteers using ultrasound. The great auricular nerve (GAN), spinal accessory nerve (SAN), transverse cervical nerve (TCN), and supraclavicular nerve (SCN) were scanned by ultrasonography in 26 healthy volunteers. The neck was scanned in the supine position with the head turned 45° to the contralateral side. The cervical plexus was detected in half of the SCM muscle. Each nerve was then traced to the level of contact with the anterior border of the SCM muscle. The following features of the nerves were recorded bilaterally: vertical and horizontal positions of each nerve at the posterior border of the SCM and the cross-sectional area and depth of each nerve at the reference line and anterior border of the SCM. The mean proportions of GAN, SAN, TCN, and SCN were 26%, 26%, 48%, and 80%, respectively near the posterior border, whereas they were 18%, 23%, and 51% for GAN, SAN, and TCN, respectively, at the level of the reference line. Notably, SCN was not visible at the level of the reference line. The mean TCN proportion was 47% at the anterior border of the SCM. The precise location of the nerves and their relationship with the SCM muscle should be considered during invasive procedures. It is recommended that the procedure be performed in the lower half of the SCM muscle, which refers to 50 to 80% of the proportions in our study.

Psychiatric Symptoms in Women with Focal Cervical Dystonia - Exploring New Pathophysiological Pathways

So far there is not much research considering female sex as a risk factor for developing focal cervical dystonia and concomitant psychiatric symptoms such as anxiety. New research proposes ideas of CD baseline pathophysiology targeting neurobiological mechanisms of gamma aminobutyric acid GABAergic function underlying sexual dimorphism and psychiatric symptoms as an intrinsic factor of the disease itself. Our research examines the connection between motor and non-motor symptoms in female patients suffering from focal cervical dystonia and their response to treatment, cit- ing the available literature and hypothesising whether it can be linked to previously described alterations in GABA levels.

Validation of a guideline to reduce variability in diagnosing cervical dystonia

BackgroundCervical dystonia is characterized by a variable pattern of neck muscle involvement. Due to the lack of a diagnostic test, cervical dystonia diagnosis is based on clinical examination and is therefore subjective. The present work was designed to provide practical guidance for clinicians in confirming or refuting suspected cervical dystonia.MethodsParticipants were video recorded according to a standardized protocol to assess 6 main clinical features possibly contributing to cervical dystonia diagnosis: presence of repetitive, patterned head/neck movements/postures inducing head/neck deviation from neutral position (item 1); sensory trick (item 2); and red flags related to conditions mimicking dystonia that should be absent in dystonia (items 3–6). Inter-/intra-rater agreement among three independent raters was assessed by k statistics. To estimate sensitivity and specificity, the gold standard was cervical dystonia diagnosis reviewed at each site by independent senior neurologists.ResultsThe validation sample included 43 idiopathic cervical dystonia patients and 41 control subjects (12 normal subjects, 6 patients with isolated head tremor, 4 with chorea, 6 with tics, 4 with head ptosis due to myasthenia or amyotrophic lateral sclerosis, 7 with orthopedic/rheumatologic neck diseases, and 2 with ocular torticollis). The best combination of sensitivity and specificity was observed considering all the items except for an item related to capability to voluntarily suppress spasms (sensitivity: 96.1%; specificity: 81%).ConclusionsAn accurate diagnosis of cervical dystonia can be achieved if, in addition to the core motor features, we also consider some clinical features related to dystonia mimics that should be absent in dystonia.

NOTCH2NLC GGC Repeat Expansion Presenting as Adult-Onset Cervical Dystonia.

FIGURE S1. Skin biopsy. P62 immunohistochemistry staining demonstrating dense, dot-like brown-colored inclusions in the nuclei of fibroblasts and cells of appendage (arrow-heads) (A). Electron microscopy shows intranuclear non-membrane bound inclusions (arrows) in the nucleus of an appendage cell (B) and a fibroblast (C). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Driving Impairment in Movement Disorders.

Driving may be adversely affected by any movement disorder, but has been mostly studied in Parkinson's disease (PD). Few studies have addressed driving impairment in patients with Huntington's disease (HD); driving in other movement disorders such as dystonia, blepharospasm and Tourette syndrome (TS) has not been adequately evaluated. The aim of this review is to summarize the findings of driving impairment in movement disorders and evaluate the usefulness of clinical tools in guiding clinicians whether to refer patients for driving assessment. A review of literature was performed on PubMed and articles on driving and movement disorders were identified using a Boolean phrase. We were able to identify 66 articles that fulfilled the target subject: impairment of driving in PD, cervical dystonia, blepharospasm, HD and TS. We also included articles discussing the role of driving rehabilitation in patients with movement disorders. Driving is often impaired in patients with PD and other movement disorders not only due to motor symptoms but also because of cognitive and behavioral co-morbidities. Certain screening tools may be helpful in guiding the clinician in referring the patients for driving assessment.

Acute cervical dystonia induced by one dose of butamirate citrate: A case report and review of literature from Hamad General Hospital Emergency, a tertiary hospital in Qatar

Dystonia is defined as abnormal muscle contraction or twisting or repetitive movements that result in sustained and abnormal posture. Cervical dystonia (CD) is one form of dystonia that involves neck muscles and leads to involuntary movements of the neck and head. Many centrally acting medications such as antipsychotics and antidepressants were reported to cause acute dystonia, as they cause an extrapyramidal side effect. We present the case of a female adult patient who had acute CD after 2 hours of the first dose of butamirate citrate, a centrally acting cough syrup, which rarely causes central nervous side effects. The patient developed neck pain, spasm, and rigidity, which worsened over time. She improved after the first dose of benztropine, an anticholinergic medication which is one of the treatment options for treating CD. This case has shown that even in OTC medications with a good safety profile, critical side effects happen, which indicates that clinicians need to be more attentive to patient’s medication history prior to critical events such as acute CD.

Evaluation of miR-526b-3p, miR-1179, miR-3529-3p, miR-5011-5p as potential diagnostic biomarkers in isolated cervical dystonia

BackgroundCervical dystonia (CD) also named spasmodic torticollis is the most common type of focal dystonias and characterized by abnormal head, neck, and shoulder movements due to involuntary muscular spasm. Although CD is mostly idiopathic, to date, several genes have been associated with CD. However, to the best of our knowledge, microRNAs (miRNAs) which are interacted with CD-associated genes have been not evaluated yet. miRNAs are regulatory small non-coding RNAs and are suggested as potential biomarkers for many diseases through their stability in clinical samples. Therefore, we aimed to assess the expression levels of miRNAs (miR-526b-3p, miR-1179, miR-3529-3p, miR-5011-5p) which are targeted the CD-associated genes, and evaluate their performance as diagnostic biomarkers. MethodsPeripheral blood samples were obtained from 30 patients with isolated CD (ICD) and 25 healthy controls. The expression levels of miR-526b-3p, miR-1179, miR-3529-3p, and miR-5011-5p were analyzed via quantitative real-time PCR (qRT-PCR), and receiver operating characteristic (ROC) curves were generated to evaluate the diagnostic values. ResultsmiR-526b-3p, miR-1179, and miR-3529-3p were significantly up-regulated while miR-5011-5p was significantly down-regulated in ICD patients compared to healthy controls. ROC analysis revealed that all miRNAs, especially miR-1179 and miR-3529-3p were statistically significant with the area under the curve (AUC) of 0.905 and 0.933, respectively. ConclusionAltered expression levels of aforementioned miRNAs may be associated with CD pathogenesis. Our findings suggest using these four miRNAs as remarkable biomarkers in the diagnosis of ICD.

Treatment of tardive dystonia: A review

Tardive dystonia (TD), the second most common but most disabling form of tardive syndrome, was initially described in 1982. It is caused by exposure to dopamine receptor blocking agents including antipsychotics and antiemetics. It most commonly presents as cranial or cervical dystonia. Characteristics suggestive of a TD diagnosis include a young age of onset, male predominance, and the higher prevalence of phasic cervical dystonia and retrocollis. Treatment of TD is limited. In this paper we review the literature on treatment options for TD as well as discussing a strategic approach. Options include use of clozapine which appears to have anti-dystonia properties. Other medications reported on with limited evidence include VMAT2 inhibitors, anticholinergics, clonazepam, and baclofen. Botulinum toxin has been shown to provide relief in TD in a manner similar to primary dystonia. The largest literature is on the use of deep brain stimulation (DBS) of the globus pallidus pars interna which includes blinded studies. We finish with providing an algorithm based on current knowledge.

Dystonia phenomenology and treatment response in migraine.

To describe the phenomenology of cervical dystonia (CD) in patients with migraine and the effect of its treatment on migraine frequency. Preliminary studies demonstrate that treatment of CD with botulinum toxin in those with migraine can improve both conditions. However, the phenomenology of CD in the setting of migraine has not been formally described. We conducted a single-center, descriptive, retrospective case series of patients with a verified diagnosis of migraine who were referred to our movement disorder center for evaluation of co-existing, untreated CD. Patient demographics, characteristics of migraine and CD, and effects of cervical onabotulinumtoxinA (BoTNA) injections were recorded and analyzed. We identified 58 patients with comorbid CD and migraine. The majority were female (51/58 [88%]) and migraine preceded CD in 72% (38/53) of patients by a mean (range) of 16.0(0-36)years. Nearly all the patients had laterocollis (57/58) and 60% (35/58) had concurrent torticollis. Migraine was found to be both ipsilateral and contralateral to the dystonia in a comparable proportion of patients (11/52 [21%] vs. 15/52 [28%]). There was no significant relationship between migraine frequency and dystonia severity. Treatment of CD with BoTNA reduced migraine frequency in most patients (15/26 [58%] at 3 months and 10/16 [63%] at 12 months). In our cohort, migraine often preceded dystonia symptoms and laterocollis was the most described dystonia phenotype. The lateralization and severity/frequency of these two disorders were unrelated, but dystonic movements were a common migraine trigger. We corroborated previous reports that cervical BoTNA injections reduced migraine frequency. Providers treating patients with migraine and neck pain who are not fully responding to typical therapies should screen for possible CD as a confounding factor, which when treated can reduce migraine frequency.

Abhimanyu Mahajan, MD, MHS, and Ludy C. Shih, MD, MMSc, FAAN, FANA

Dr. Abhimanyu Mahajan is Assistant Professor of Neurological Sciences in the Rush Parkinson's Disease and Movement Disorders program at Rush University Medical Center in Chicago, IL. After medical school in Mumbai, India, Dr. Mahajan obtained a Masters in Epidemiology with a concentration in aging at the Johns Hopkins Bloomberg School of Public Health and a certificate in gerontology from the Johns Hopkins Center of Aging and Health in Baltimore, MD. He completed his Neurology Residency at Henry Ford Hospital in Detroit and Movement Disorders fellowship at the University of Cincinnati, where he was the 2019 Dystonia Medical Research Foundation (DMRF) clinical fellow. Dr. Mahajan has received funding from the DMRF, Sunflower Parkinson's Disease Foundation, and the Parkinson's Foundation. He is a member of the 2022 Movement Disorders Society (MDS) LEAP class. For his work on cervical dystonia and substance abuse using the Dystonia Coalition database, he received the 2018 American Academy of Neurology (AAN) Young Investigators Award. He received the 2018 Junior Investigator Award from the Parkinson Study Group for his work using magnetoencephalography in cervical dystonia. His efforts on exploring the clinical relationship between cancer and Parkinson's disease, biological opposites, led to the 2020 AAN Alliance Award: Founders. Currently, he serves on the AAN Graduate Education Subcommittee, AAN Movement Disorders Measurement Workgroup, and the MDS Dystonia Study Group.

Secondary dystonia following parenchymal brain tumors

BackgroundSecondary dystonia has been associated with diverse etiologies. Dystonia associated with brain tumors has not been well characterized. ObjectivesTo characterize dystonia and relationship with parenchymal brain tumors. MethodsWe present six patients (1.03%) with dystonia related to parenchymal brain tumors, among 580 screened cases. ResultsContralateral hemidystonia was observed in four cases, followed by focal limb (n = 1) and cervical dystonia (n = 1). Dystonia presented during the phase of tumor growth in four cases, and following tumor treatment in two, one case had re-emergent dystonia. Tumors were low-grade (WHO I or II) and located in the basal ganglia (n = 3), cortical areas (n = 2), thalamus (n = 1) and cerebral peduncle (n = 1). ConclusionsSecondary dystonia may be caused by brain tumors in diverse locations including basal ganglia, cortex and thalamus. It may be the presenting symptom of brain tumor or follow surgical resection combined with ancillary therapy.

Gut Microbiome Composition in Dystonia Patients.

Dystonia is a movement disorder in which patients have involuntary abnormal movements or postures. Non-motor symptoms, such as psychiatric symptoms, sleep problems and fatigue, are common. We hypothesise that the gut microbiome might play a role in the pathophysiology of the (non-)motor symptoms in dystonia via the gut-brain axis. This exploratory study investigates the composition of the gut microbiome in dystonia patients compared to healthy controls. Furthermore, the abundance of neuro-active metabolic pathways, which might be implicated in the (non-)motor symptoms, was investigated. We performed both metagenomic and 16S rRNA sequencing on the stool samples of three subtypes of dystonia (27 cervical dystonia, 20 dopa-responsive dystonia and 24 myoclonus-dystonia patients) and 25 controls. While microbiome alpha and beta diversity was not different between dystonia patients and controls, dystonia patients had higher abundances of Ruminococcus torques and Dorea formicigenerans, and a lower abundance of Butyrivibrio crossotus compared to controls. For those with dystonia, non-motor symptoms and the levels of neurotransmitters in plasma explained the variance in the gut microbiome composition. Several neuro-active metabolic pathways, especially tryptophan degradation, were less abundant in the dystonia patients compared to controls. This suggest that the gut-brain axis might be involved in the pathophysiology of dystonia. Further studies are necessary to confirm our preliminary findings.

Social cognition in cervical dystonia

BackgroundWhilst traditionally considered a movement disorder, it is now generally accepted that cervical dystonia (CD) presents with additional non-motor symptoms which significantly impact quality of life. Our study primarily aimed to explore social cognition and levels of psychological distress in individuals with CD, in comparison to age- and sex-matched healthy controls. Methods20 participants with CD attending a specialist movement disorders clinic were recruited. 20 age and sex matched neurologically healthy controls were recruited in parallel. Participants completed the Hospital Anxiety and Depression Scale, and two novel social cognition tasks: The Cambridge Mindreading Face-Voice Battery (CAFMB) and the Edinburgh Social Cognition Test (ESCoT). ResultsParticipants with CD exhibited poorer complex emotion recognition abilities for visual and auditory stimuli, compared to controls on the CAFMB task. Participants with CD did not differ significantly from controls on performance on cognitive or affective Theory of Mind tasks, or interpersonal or intrapersonal understanding of social norms, as measured by the ESCoT. The proportion of depressive symptoms was significantly higher for participants with CD than controls. 40% of participants with CD reported clinically elevated depressive symptoms, and 60% reported clinically elevated anxiety. Poorer understanding of emotional facial expressions was associated with higher levels of depression in the CD group. ConclusionsSignificant between-group differences between participants with CD and controls suggests socio-cognitive dysfunction is an important aspect of the non-motor syndrome of CD. Findings highlight the need for assessment of and intervention for both social cognitive difficulties and psychological distress in individuals with CD.

Impaired trunk control and its relationship with balance, functional mobility, and disease severity in patients with cervical dystonia.

Impaired trunk control is common in neurological disorders; however, trunk control has not been examined in patients with cervical dystonia (CD). Therefore, the primary aim was to compare trunk control between patients with CD and healthy people. The secondary aim was to investigate the relationship between trunk control and balance, functional mobility, and disease severity in patients with CD. ]This cross-sectional study included 32 patients with CD and 32 healthy people. Trunk control was compared using the trunk impairment scale (TIS) that consists of three subscales: static sitting balance, dynamic sitting balance, and trunk coordination between two groups. Balance was assessed using Berg Balance Scale, four square step test, and one-leg stance test. The Timed Up and Go Test was measured to determine functional mobility. Toronto Western Spasmodic Torticollis Rating Scale was used to evaluate disease severity.]></AbstractText> <AbstractText Label="RESULTS"><![CDATA[ Patients with CD demonstrated worse performance on the TIS-total with TIS-dynamic sitting subscale and TIS-trunk coordination subscale (p < 0.001, p < 0.001, and p < 0.001), except for TIS-static sitting subscale (p = 0.078) compared to healthy people. TIS-total scores had moderate to strong correlations with balance, functional mobility, and disease severity (range r between 0.786 and 0.536, p < 0.05 for all). There was no correlation between TIS-total scores and disease severity (p = 0.102). Patients with CD had impaired trunk control, especially in dynamic sitting balance and trunk coordination. Impaired trunk control was also associated with balance and functional mobility but not disease severity. These findings suggest that trunk control deficits should receive attention in the assessment and treatment of patients with CD.

DYT30 due to VPS16 Mutation: An Etiology of Childhood-Onset Generalized Dystonia.

DYT30 due to VPS16 Mutation: An Etiology of Childhood-Onset Generalized Dystonia.

Social cognition deficits are associated with lower quality of life in cervical dystonia: A single centre study

Background and objectivesPatients with cervical dystonia (CD) demonstrate significant non-motor symptoms including sensory, psychiatric and cognitive features. It has been shown that the non-motor symptoms have a major influence on quality of life. Social cognition, particularly deficits in Theory of Mind (ToM), can affect the development of interpersonal relationships, understanding of social situations and can affect patient outcomes.We used the “Faux Pas” measure of social cognition to assess ToM in patients with CD and compared this with quality of life, disease severity and psychiatric symptoms. MethodsPatients with adult-onset idiopathic isolated cervical dystonia were assessed using the “Faux Pas” questionnaire. Validated questionnaires were used to assess mood symptoms (BAI/BDI and HADS) and quality of life (CDIP-58). Disease-specific disability, motor severity and psychosocial symptoms were measured using TWSTRS2. Faux pas results were compared with published healthy control values. Results32 participants (19 female) were included with a mean age of 57.7 years. 20 participants met criteria for excess mood symptoms (anxiety and/or depression). Mean CDIP-58 was 31.9. There was no relationship between faux pas outcomes and motor severity. However, correlation analyses showed that participants who performed worse on the faux pas questionnaire had lower quality of life. ConclusionThe non-motor symptoms, including social cognition, are often neglected. We have demonstrated that low quality of life in CD is associated with to abnormal social cognition. Clinicians should be mindful of these symptoms, particularly in patients reporting low treatment satisfaction.

Cortical mechanisms of sensory trick in cervical dystonia

Patients with cervical dystonia (CD) often show an improvement in dystonic posture after sensory trick (ST), though the mechanisms underlying ST remain unclear. In this study, we aimed to investigate the effects of ST on cortical activity in patients with CD and to explore the contribution of motor and sensory components to ST mechanisms. To this purpose, we studied 15 CD patients with clinically effective ST, 17 without ST, and 14 healthy controls (HCs) who mimicked the ST. We used electroencephalographic (EEG) recordings and electromyography (EMG) data from bilateral sternocleidomastoid (SCM) muscles. We compared ST-related EEG spectral changes from sensorimotor and posterior parietal areas and EMG power changes between groups. To better understand the contribution of motor and sensory components to ST, we tested EEG and EMG correlates of three different conditions mimicking ST, the first without skin touch (“no touch” condition), the second without voluntary movements (“passive” condition), and finally without arm movements (“examiner touch” condition).Results showed ST-related alpha desynchronization in the sensorimotor cortex and theta desynchronization in the sensorimotor and posterior parietal cortex. Both spectral changes were more significant during maneuver execution in CD patients with ST than in CD patients without ST and HCs who mimicked the ST. Differently, the “no touch”, “passive”, or “examiner touch” conditions did not show significant differences in EEG or EMG changes determined by ST execution/mimicking between CD patients with or without ST. A higher desynchronization within alpha and theta bands in the sensorimotor and posterior parietal areas correlated with a more significant activity decrease in the contralateral SCM muscle, Findings from this study suggest that ST-related changes in the activity of sensorimotor and posterior parietal areas may restore dystonic posture and that both motor and sensory components contribute to the ST effect.

Does Pallidal Physiology Determine the Success of Unilateral Deep Brain Stimulation in Cervical Dystonia?

Pallidal deep brain stimulation is a well-known surgical treatment for cervical dystonia. The resolution of dystonia typically requires bilateral pallidal stimulation, but in some instances, unilateral stimulation has been successful. In such instances, generally, the stimulated hemisphere was contralateral to the dystonic sternocleidomastoid, but rarely it was ipsilateral. We sought for the physiological features that determine the basis for success and laterality of deep brain stimulation for cervical dystonia with prominent torticollis. We found that pallidal physiology such as high burst to tonic ratio and significant interhemispheric differences in the neuronal firing rate and regularity are critical determinants of successful treatment with unilateral deep brain stimulation. We also found that higher lateralized differences in pallidal physiological parameters predict more robust improvement. In three out of four patients, the stimulation of the hemisphere ipsilateral to the dystonic sternocleidomastoid muscle was effective. These patients did not have any structural brain abnormalities on clinically available imaging studies. One patient responded to the unilateral deep brain stimulation in the hemisphere contralateral to the dystonic sternocleidomastoid. This patient had a structural putamen lesion on brain MRI. These results provide objective parameters determining the success of pallidal deep brain stimulation for treatment of cervical dystonia. The results also depict differences in the pallidal physiology in patients where ipsilateral versus contralateral deep brain stimulation was effective.