Spontaneously changing muscular activation pattern in patients with cervical dystonia

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.

Involvement of obliquus capitis inferior muscle in dystonic head tremor

INTRODUCTION

Head tremor is a common feature in cervical dystonia (CD) and often less responsive to botulinum neurotoxin (BoNT) treatment than dystonic posturing. Ultrasound allows accurate targeting of deeper neck muscles.

METHODS

In 35 CD patients with dystonic head tremor the depth and thickness of the splenius capitis (SPL), semispinalis capitis and obliquus capitis inferior muscles (OCI) were assessed using ultrasound. Ultrasound guided EMG recordings were performed from the SPL and OCI.

RESULTS

Burst-like tremor activity was present in both OCI in 25 and in one in 10 patients. In 18 patients, tremor activity was present in one SPL and in 2 in both SPL. Depth and thickness of OCI, SPL and semispinalis capitis muscles were very variable.

CONCLUSION

Muscular activity underlying tremulous CD is most commonly present in OCI. Due to the variability of muscle thickness, we suggest ultrasound guided BoNT injections into OCI.

Dystonia as a patterned motor malflow

The definition of dystonia has been renewed repeatedly but always within the context of overactive muscle contractions. In dystonia the muscles unnecessary for a motion fail to be adequately suppressed because of the loss of central motor control, resulting in inappropriate movements or abnormal postures ("overflow phenomenon"). This represents, however, only one side of the disrupted motor control. Some patients complain of the inability to activate muscles necessary for the intended task despite the lack of motor paresis, as best exemplified by the apraxia of eyelid opening. The author has ever coined the term "negative dystonia" for this phenomenon, which occurs hypothetically as a result of failed central motor flow and is often co-existent with overflow. Negative dystonia has a fixed pattern and sensory trick may be effective to ameliorate the symptom just as in the case of conventional dystonia. Hence we can speculate that the overflow and flow failure are the two sides of the same coin, both being caused by the loss of motor control. The current hypothesis is that dystonia is a representation of the patterned motor malflow (malicious flow) due to the loss of motor control.

The occurrence of lateral shift in cervical dystonia

Aim of this study is to identify factors contributing the occurrence of neck lateral shift (LS) in patients with cervical dystonia (CD). A retrospective analysis focused on the treatment with botulinum toxin (BTX) was conducted on 38 consecutive idiopathic CD patients comparing subjects with and without LS. The main result was the evidence of a significantly higher BTX inter-side dose difference in patients with LS suggesting that this uncommon phenotype may be an artifact of chronic therapy with BTX.

Selective peripheral denervation for cervical dystonia: long-term follow-up

OBJECTIVE

61 procedures with selective peripheral denervation for cervical dystonia were retrospectively analysed concerning surgical results, pain, quality of life (QoL) and recurrences.

METHODS

The patients were assessed with the Tsui torticollis scale, Visual Analogue Scale (VAS) for pain and Fugl-Meyer scale for QoL. Evaluations were performed preoperatively, early postoperatively, at 6 months, then at a mean of 42 (13-165) months. All patients underwent electromyogram at baseline, which was repeated in cases who presented with recurrence of symptoms after surgery.

RESULTS

Six months of follow-up was available for 55 (90%) of the procedures and late follow-up for 34 (56%). The mean score of the Tsui scale was 10 preoperatively. It improved to 4.5 (p<0.001) at 6 months, and 5.3 (p<0.001) at late follow-up. VAS for pain improved from 6.5 preoperatively to 4.2 (p<0.001) at 6 months and 4 (p<0.01) at late follow-up. The Fugl-Meyer score for QoL improved from 43.3 to 46.6 (p<0.05) at 6 months, and to 51.1 (p<0.05) at late follow-up. Major reinnervation and/or change in the dystonic pattern occurred following 29% of the procedures, and led in 26% of patients to reoperation with either additional denervation or pallidal stimulation.

CONCLUSIONS

Selective peripheral denervation remains a surgical option in the treatment of cervical dystonia when conservative measures fail. Although the majority of patients experience a significant relief of symptoms, there is a substantial risk of reinnervation and/or change in the pattern of the cervical dystonia.

Electrophysiological and structural MRI correlates of dystonic head rotation in drug-naïve patients with torticollis

INTRODUCTION

We tested whether a change in head/neck position initiates head deviation in drug-naïve patients with cervical dystonia and to identify the electrophysiological and neuroanatomical correlates of dystonic head rotation.

METHODS

Twenty-five consecutive drug-naïve patients with cervical dystonia and 25 healthy controls underwent the simultaneous surface electromyographic (EMG) recording of sternocleidomastoid (SCM) muscle contractions during head/neck position changes, blink reflex recovery cycle (BRrc), DAT-SPECT, and advanced structural neuroimaging analysis using voxel-based morphometry (VBM).

RESULTS

Surface EMG recordings of SCM muscle activity during changes in head/neck position demonstrated an insignificant asymmetric low amplitude of the SCM muscle contractions in the horizontal position in both patients and controls, but an asymmetric high amplitude in SCM muscle contractions leading to abnormal head movements in vertical positions in patients with cervical dystonia. All controls had a symmetric low increase in amplitude of SCM muscle contractions in response to changes in head/neck position. VBM analysis in 19 patients showed abnormal decreases of gray matter (GM) volume in the bilateral motor (localized in the homunculus of the head) and premotor cortices when compared to controls. In addition, the side of these neuroanatomical changes was asymmetrically related to abnormal head deviations in these patients. All subjects had normal results during BRrc and DAT-SPECT.

CONCLUSIONS

The passage from inactive horizontal position to active vertical head/neck posture initiates head deviation in drug-naïve patients with cervical dystonia, and the anatomical correlates of this dystonic head rotation is a restricted abnormal pattern of GM changes in the motor cortices.

[Clinical characteristics and treatment of dystonia]

Dystonia is defined as a syndrome of sustained muscle contractions, frequently causing twisting and repetitive movements, or abnormal postures. Its diagnosis is based on clinical characteristics. In dystonia, the pattern of abnormal posture or movement tends to be constant during the short term even if its severity fluctuates. This stereotypy often helps differentiate dystonia from psychogenic reaction. Dystonia may appear only during some specific task (task specificity) especially in its early phase, although it often becomes obscure during the long clinical course, resulting in persistent dystonic posture. Sensory trick or geste antagoniste means the change of severity triggered by some sensory input Overflow phenomenon is the activation of muscles unnecessary to a task, hampering purposeful movement. Symptoms tend to be milder in the morning, with large individual variation of its duration (morning benefit). Symptoms of dystonia may abruptly appear or disappear (flip-flop phenomenon). Cocontraction, believed as an essential feature of dystonia, reflects a loss of reciprocal inhibition of muscle activities, causing involuntary simultaneous contractions of agonists and antagonists. "Negative dystonia," still an unaccepted feature of dystonia, is defined as non-paretic loss of central driving of muscle activities necessary to a task. Apraxia of lid opening/closure, paretic form of hand dystonia, dropped head syndrome, camptocormia, Pisa syndrome, cervical dystonia with limited range of head movement, or mandibular dystonia without cocontractions of masticatory muscles, can be explained with this concept at least in a subset of cases. Treatment of dystonia includes medication, botulinum toxin injection, intrathecal baclofen, surgical intervention, acupuncture and other alternative therapies, rehabilitation, and psychotherapy. Oral medication is usually an adjunct to more potent therapeutic options except for some specific indications like dopa-responsive dystonia. Botulinum toxin is usually the treatment of choice for focal dystonia. Deep brain stimulation can be considered for both focal and non-focal phenotypes of dystonia.

Clinical changes of cervical dystonia pattern in long-term botulinum toxin treated patients

Cervical dystonia (CD) is a complex disorder but the response to long-term botulinum toxin (BTX) therapy is satisfactory in most cases. Bad results are attributed by some authors to changes in muscle activation. Our purpose is to verify if the change in head deviation affects negatively the response to BTX therapy in a long-term follow-up, and if there are any differences in clinical parameters of these patients in comparison to those with stable pattern. From a total of 88 patients evaluated at the Movement Disorders Clinics of Hospital das Clinicas - University of São Paulo School of Medicine between January 1993 and December 2005, 67 were included. In 24 (35.8%) change in pattern of CD was observed, in a medium follow-up period of 80 months. The time between onset of dystonia and the diagnosis of pattern change was 9.7 years. Comparing with patients with no changes in CD pattern, there were no significant statistical differences. Improvement of symptoms around 60% was reported in both groups. In conclusion, the change in head deviation observed in CD was not responsible for bad response to therapy with BTX and there were no significant differences between both groups.

Botulinum toxin: description of injection techniques and examination of controversies surrounding toxin diffusion

The benefits derived from botulinum toxin (BTX) injections may be negated by unintentional weakness of adjacent uninjected muscles. Such weakness may be the result of inaccurate targeting, or diffusion of BTX to surrounding muscles. Several techniques, using electromyographic, endoscopic or imaging guidance are purported to increase the accuracy of targeting. Diffusion of BTX is thought to be influenced by factors such as dose, concentration, injectate volume, number of injections, site and rate of injection, needle gauge, muscle size, muscular fascia, distance of needle tip from the neuromuscular junction, and protein content of the BTX formulation. This article describes techniques that aim to increase the accuracy of BTX injections and examines the controversies surrounding diffusion of BTX following injection.

Deep brain stimulation for treatment of cervical dystonia

Pallidal deep brain stimulation is an efficient treatment option in those patients with cervical dystonia who do not benefit from conservative treatment including local botulinum toxin injections. Given the fact that other surgical treatment options such as selective peripheral denervation are available, it may be considered third-line treatment in most instances. Chronic bilateral pallidal stimulation improves dystonic posture and movements, pain caused by dystonia and disability related to dystonia. Preliminary data on longterm follow-up confirm its beneficial effect in the majority of patients. Given the frequency of cervical dystonia, pallidal deep brain stimulation will play a major role in the future.

Botulinum toxin-A injections for spastic toe clawing

Spastic toe clawing describes extension at the metatarsophalangeal joints of the feet, flexion at the proximal interphalangeal joints and flexion at the distal interphalangeal joints that results from upper motor neuron lesions, such as stroke, intracranial hemorrhage, cervical myelopathy and brain tumors. Even though toe clawing is often asymptomatic, it can be painful. Previous studies have described the efficacy of injections of botulinum toxin type-A (BTX-A) to the long flexors of the toes, but this is often unsatisfactory as high dosages (up to 175 units) have been required, and patients often report significant residual toe clawing. We performed an open label, prospective study to assess the efficacy of BTX-A injections, targeting the long and short flexors of the toes, performed with electrical (motor point) stimulation under electromyographic guidance. Outcome measures, which included timed walking over 20m, objective assessment of toe clawing (modified Ashworth scale and a visual analog scale rating) and patient assessment of functional disability, were assessed before injections and at six-weeks' follow-up. Seven patients (five male and two female) of mean age 51 (range 38-70) were recruited. Four had spasticity from underlying intracranial hemorrhage, the remaining three from cerebral infarct, astrocytoma and post-traumatic cervical myelopathy. The total dose of BTX-A injected for toe clawing ranged from 40 to 90 units. Improvements were observed in all outcome measures except timed walking. Injecting BTX-A to the long and short flexors of the toes, with electrical stimulation under electromyographic guidance, is well tolerated and efficacious in the treatment of toe clawing from spasticity, allowing for lower dosages to be used.

Efficacy and safety of repeated doses of botulinum toxin type B in type A resistant and responsive cervical dystonia

Efficacy of botulinum toxin type B (BoNT B) for the treatment of type A-resistant (AR) and non-A-resistant (NAR) cervical dystonia (CD) has been demonstrated in several single injection studies. There is little data available on long-term therapy with repeated injection sessions and it is unknown if AR and NAR patients respond in a similar manner over time. To evaluate the long-term efficacy and safety of BoNT B in AR and NAR CD patients, we carried out a prospective, open-label study examining 10 repeated dosing sessions of BoNT B in 34 patients with CD (15 AR and 19 NAR). Dosing was started at 10,000 units and could be increased to 25,000. Assessments included the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) and a patient global assessment at each baseline (injection) and Week 4 (peak effect) visit. Change in TWSTRS total was the primary efficacy end point. Data was analyzed using repeated-measures analysis of variance. BoNT B therapy resulted in an overall significant improvement of CD (P<0.001) and improvement was seen in all 10 individual sessions (2.5 years). The magnitude of response decayed over time (P<0.001). There was no difference between AR and NAR patients with regard to dose, treatment effect, or decay in response. The AR group perceived (patient global) treatment as being less effective (P=0.047). Dry mouth frequency decreased with each session despite increasing doses whereas flu-like syndrome and weakness increased. BoNT B therapy provides long-term benefit for CD patients but the magnitude of response diminishes over time. The cause of this decay is probably multifactorial. AR and NAR CD patients respond in a similar fashion.

Botulinum toxin A for the treatment of cervical dystonia

Idiopathic cervical dystonia (ICD) is the most common adult-onset focal dystonia. It is characterised by relatively sustained, involuntary contractions of neck muscles. Injections of botulinum toxin (BTX)-A are safe and effective for the treatment of ICD, and have substantially improved its treatment. BTX-A is manufactured by Allergan Pharmaceuticals in the US and Ireland, and is distributed as Botox. In Europe, BTX-A is manufactured and distributed by Ipsen Pharmaceuticals as Dysport. Success rates for BTX-A injections for ICD ranges 64-90%, with 76-93% of injected patients experiencing pain reduction. Side effects are generally mild and include dysphagia and neck weakness.

Reduction of cervical dystonia after an extended course of chiropractic manipulation: a case report

OBJECTIVE

The diminution of the signs and symptoms of cervical dystonia following an extended course of specific chiropractic manipulation is described.

CLINICAL FEATURES

A 38-year-old man had gross anterior-lateral torticollis, focal dystonia of the head and neck, and radicularlike pains which failed to respond to physical therapy, medication, and injection.

INTERVENTIONS AND OUTCOMES

Two specific spinal manipulative technique systems unique to the chiropractic profession (Applied Biostructural Therapy [ABT] and Atlas Coccygeal Technique [ACT]) were applied to the patient. The patient's grading on a modified cervical dystonia scale dropped from a grade 16 to a grade 5 after an extended course of these specific chiropractic manipulative techniques.

CONCLUSIONS

The application of Advanced Biostructural Therapy and Atlas Coccygeal chiropractic techniques for management of cervical dystonia is presented. Substantial reduction in the cervical dystonia rating scale was observed with this approach, even after standard medical interventions had failed.

Automated assessment of cervical dystonia

We developed an automated and objective method to measure posture and voluntary movements in patients with cervical dystonia using Fastrack, an electromagnetic system consisting of a stationary transmitter station and four sensors. The junction lines between the sensors attached to the head produced geometrical figures on which the corresponding aspects of the head were superimposed. The head position in the space was reconstructed and observed from axial, sagittal, and coronal planes. Four patients with cervical dystonia and 6 healthy subjects were studied. Each patient was representative of one of the typical patterns of cervical dystonia. The study allowed the authors to collect quantitative data on posture and range of motion of the head. This pilot study demonstrates the efficacy of the Fastrack system to objectively measure the head position in cervical dystonia patients.