Botulinum toxin injections reduce associative plasticity in patients with primary dystonia

Botulinum toxin injections ameliorate dystonic symptoms by blocking the neuromuscular junction and weakening dystonic contractions. We asked if botulinum toxin injections in dystonia patients might also affect the integrity of sensorimotor cortical plasticity, one of the key pathophysiological features of dystonia. We applied a paired associative stimulation protocol, known to induce long‐term potentiation–like changes in the primary motor cortex hand area to 12 patients with cervical dystonia before and 1 and 3 months after botulinum toxin injections to the neck muscles. Primary motor cortex excitability was probed by measuring transcranial magnetic stimulation‐evoked motor evoked potentials before and after paired associative stimulation. We also measured the input–output curve, short‐interval intracortical inhibition, intracortical facilitation, short afferent inhibition, and long afferent inhibition in hand muscles and the clinical severity of dystonia. Before botulinum toxin injections, paired associative stimulation significantly facilitated motor evoked potentials in hand muscles. One month after injections, this effect was abolished, with partial recovery after 3 months. There were significant positive correlations between the facilitation produced by paired associative stimulation and (1) the time elapsed since botulinum toxin injections and (2) the clinical dystonia score. One effect of botulinum toxin injection treatment is to modulate afferent input from the neck. We propose that subsequent reorganization of the motor cortex representation of hand muscles may explain the effect of botulinum toxin on motor cortical plasticity. © The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.     

Change in the pattern of cervical dystonia might be the cause of benefit loss during botulinum toxin treatment

The muscular patterns of cervical dystonia were identified by polymyographic recordings in 76 patients before botulinum toxin treatment. The leading muscles were considered to be those which started dystonic movement and which showed constant and maximal activity during all dystonic movements. The dystonic muscles were repeatedly treated by local Injections of botulinum toxin. Sixteen patients showed (after repeated injections) loss of the benefit of local applications of botulinum toxin after various periods of time. Repeated polymyographic recordings were performed in these patients during the loss of the benefit of injected botulinum toxin. In four patients repeated polymyographic recordings showed an Identical pattern of cervical dystonia, but the activity of previously injected muscles was apparently decreased. In 12 patients only minimum or no activity was recorded in muscles which had previously been treated with botulinum toxin, but the pattern of cervical dystonia was changed. Different patterns of cervical dystonia with different leading muscles, but with identical directions of head deviation, were observed in six patients. In another six patients, the head deviation direction was to the opposite side and was accompanied by a change of the leading muscle and a change of the muscular pattern of dystonia. These results suggest either that dystonic activity from the cerebral generator changes to new effectors during the peripheral blockade of primary dystonic muscles, or that a change of generators at different levels of the CNS occurs. It may be neccessary to carry out repeated polymyographic recordings throughout the period of loss of benefit of previously successful local botulinum toxin injections.     

Long-term follow-up by video of cervical dystonia treated with botulinum toxin

We have analysed video recordings of 21 patients with cervical dystonia treated with botulinum toxin. Fourteen patients have a record both of their response shortly after injections were commenced and between four years five months and six years seven months later. Our analysis shows that the long term outcome is often better than the initial response. We suggest that chronic treatment with botulinum toxin allows different muscles to those initially injected to be identified as contributors to the dystonia. Subsequent injection of these muscles leads to further improvement. It implies that cervical dystonia is a more widespread disorder of motor control, rather than simply limited to a few muscles.     

Accuracy of muscle localization without EMG: implications for treatment of limb dystonia

Although botulinum toxin is an effective treatment for focal dystonia, the importance of electromyography (EMG) in identifying muscles and guiding injections is unclear. The authors examined the accuracy of muscle localization in 38 muscles in patients with focal hand dystonia without EMG guidance. Only 37% of needle placement attempts reached the target muscles or muscle fascicles. This study demonstrates that EMG guidance is needed for correct localization of desired muscles.     

Fluoroscopic, EMG-guided injection of botulinum toxin into the longus colli for the treatment of anterocollis

BackgroundAnterocollis is a form of cervical dystonia characterized by forward neck flexion. While botulinum toxin is the treatment of choice for cervical dystonia, patients with anterocollis, who receive injections into the sternocleidomastoid and anterior scalene muscles, represent a disproportionate number of treatment failures. Deep cervical muscles such as the longus colli likely play an important role in neck flexion but are not routinely injected.ObjectiveTo describe a technique for longus colli injection in cases of anterocollis and to report the clinical outcomes of 10 such injections of botulinum toxin.MethodsThree patients were referred for evaluation and treatment of anterocollis. All had previous treatment failures with sternocleidomastoid/anterior scalene injections or no activity noted on needle EMG investigation of these muscles. All patients received injections of botulinum toxin into the longus colli under fluoroscopic and EMG guidance.ResultsAll patients experienced symptomatic improvement (eight of 10 injections). Two patients reported mild dysphagia without serious complications after dose increases in botulinum toxin.ConclusionsIncomplete muscle selection may be one cause of treatment failures in anterocollis. Deep cervical flexors such as the longus colli represent an under-recognized potential target for symptomatic treatment of anterocollis.     

Muscle selection for treatment of cervical dystonia with botulinum toxin--a systematic review

RationaleCervical dystonia, also called spasmodic torticollis, is the most common form of (primary) dystonia. Intramuscular injections with botulinum toxin are the first line of treatment for cervical dystonia. To optimise the treatment response to botulinum toxin correct muscles should be selected. Clinical evaluation is important for muscle selection but the value of additional tests to identify dystonic muscles remains unclear.ObjectiveTo evaluate all relevant literature regarding the best approach to select dystonic muscles for treatment with botulinum toxin.MethodsWe conducted a systematic review of studies that had investigated methods of selecting muscles for treatment with botulinum toxin. In addition, we compared all prospective botulinum toxin trials using either clinical evaluation or polymyographic electromyography for muscle selection.ResultsForty relevant studies were included and polymyographic electromyography recordings were most often employed. In several studies, polymyographic electromyography revealed a different pattern of muscle involvement compared to that found during clinical evaluation. In one randomized controlled trial polymyographic electromyography significantly improved the outcome of botulinum toxin treatment. A limited number of studies used positron emission tomography – computed tomography imaging or frequency analysis of the electromyography signal to identify dystonic muscles but their effect on the outcome of treatment has never been studied.ConclusionPolymyographic electromyography may improve the outcome of botulinum toxin treatment in cervical dystonia, but evidence is limited and larger studies are needed.     

Utility of an EMG mapping study in treating cervical dystonia

Intramuscular injections of botulinum toxin are the cornerstone of treatment for cervical dystonia. Controversy exists regarding the necessity for EMG-guided injections. We compared the clinical examination of four movement disorder specialists to an electromyographic (EMG) mapping study. Clinical predictions of individual muscle involvement were only 59% sensitive and 75% specific. Muscle hypertrophy, shoulder elevation, and dominant head vector did not bolster clinical accuracy. An EMG mapping study facilitates identification of dystonic muscles in cervical dystonia, which may enhance botulinum toxin therapy.     

Reversible reorganisation of the motor cortical representation of the hand in cervical dystonia.

Previous work has suggested that there may be a widespread disturbance of motor control mechanisms in patients with cervical dystonia. In the present study, we used transcranial magnetic stimulation to investigate the topography of the corticomotor projection to the abductor pollicis brevis (APB) muscle in 10 subjects with idiopathic torticollis. Threshold-adjusted stimuli were delivered at multiple scalp sites during a low-level voluntary contraction of the APB, and maps were generated of motor evoked potential amplitude versus scalp site. The cortical maps for the APB on the side opposite to the direction of head rotation were displaced laterally or posteriorly in all subjects and reverted to a more normal position after botulinum toxin injection of the cervical muscles in 5 subjects. The findings point to a reversible reorganisation of the corticomotor representation of the hand on the same side as the sternocleidomastoid (SCM) muscle that is involved in producing the dystonia. These results provide further evidence for the involvement of cortical centres and for a more widespread abnormality of motor control mechanisms in focal dystonia. The findings also support the notion that head turning is chiefly mediated by the hemisphere ipsilateral to the direction of the head rotation by means of a corticomotor projection to the contralateral SCM.     

An open trial of levetiracetam for segmental and generalized dystonia.

Local botulinum toxin injections represent the treatment of choice for most patients with focal dystonia. However, patients with segmental or generalized forms require additional pharmacologic treatment which is often ineffective or limited by intolerable side-effects. An animal study and three case reports suggested antidystonic effects of levetiracetam, a pyrrolidone derivate, whereas a recent open-label study found no improvement in 10 patients with primary idiopathic cervical dystonia. We studied the efficacy of levetiracetam in a daily dose of 3000 mg in 10 consecutive patients with otherwise therapy refractory segmental or generalized dystonia. At 4-week follow-up, none of the patients showed improvement of dystonia, mild side-effects were observed in 3 patients.     

Paramedical treatment in primary dystonia: A systematic review

Dystonia is a disabling movement disorder with a significant impact on quality of life. The current therapeutic armamentarium includes various drugs, botulinum toxin injections, and occasionally (neuro)surgery. In addition, many patients are referred for paramedical (including allied health care) interventions. An enormous variation in the paramedical treatment is provided, largely because evidence‐based, accepted treatment regimes are not available. We have conducted a systematic review of studies that explored the effect of various paramedical interventions in primary dystonia. Only studies that have used clinical outcome measures were included. There were no class A1 or A2 studies and therefore, level 1 or 2 practice recommendations for a specific intervention could not be deducted. Many papers were case reports, mostly with a very limited number of patients and a clear publication bias for beneficial effects of a particular paramedical intervention. Some potentially interesting interventions come from class B studies, which include physical therapy in addition to botulinum toxin injections (BoNT‐A) in cervical dystonia; sensorimotor training and transcutaneous electrical nerve stimulation (TENS) in writer's cramp; and speech therapy added to BoNT‐A injections in laryngeal dystonia. Good quality clinical studies are therefore warranted, which should have the aim to be generally applicable. A design in which the paramedical intervention is added to a current gold standard, for example, BoNT‐A injections in cervical dystonia, is recommended. © 2009 Movement Disorder Society     

Botulinum toxin treatment of cranial-cervical dystonia, spasmodic dysphonia, other focal dystonias and hemifacial spasm.

In the past five years, 477 patients with various focal dystonias and hemifacial spasm received 3,806 injections of botulinum A toxin for relief of involuntary spasms. A definite improvement with a global rating greater than or equal to 2 on a 0-4 scale, was obtained in all 13 patients with spasmodic dysphonia, 94% of 70 patients with blepharospasm, 92% of 13 patients with hemifacial spasm, 90% of 195 patients with cervical dystonia, 77% of 22 patients with hand dystonia, 73% of 45 patients with oromandibular dystonia, and in 90% of 21 patients with other focal dystonia who had adequate follow up. While the average duration of maximum improvement lasted about 11 weeks after an injection (range seven weeks in patients with hand dystonia to 15 weeks in patients with hemifacial spasm), some patients benefited for over a year. Only 16% of the 941 treatment visits with follow up were not successful. Except for transient focal weakness, there were very few complications or systemic effects attributed to the injections. This study supports the conclusion that botulinum toxin injections are a safe and effective therapy for patients with focal dystonia and hemifacial spasm.     

A practical approach to management of focal hand dystonia

Dystonia can be focal, segmental, multifocal, generalized, or hemidystonia. Focal dystonia is localized to a specific part of the body. Overall upper limb is more commonly involved in focal dystonia than lower limb and since it starts from hand, focal hand dystonia (FHD) is a more accepted terminology. Writer''s cramp and musician dystonia are commonest types of FHD. Typically this dystonia is task specific, but in some patients this specificity may be lost over a period of time. Segmental or generalized dystonia may also start as FHD, so a detailed clinical assessment is required, which should be supplemented by relevant investigations. Treatment includes oral medications, injection botulinum toxin, neurosurgery including neurostimulation, and rehabilitation. Role of injection botulinum toxin has been extensively studied in writer''s cramp patients and found to be effective; however, selection of muscles and techniques of injection are crucial in getting best results.     

Electromyographic evaluation of cervical dystonia for planning of botulinum toxin therapy

The success of botulinum toxin (BT) injections for treatment of cervical dystonia depends on precise identification of dystonic muscles and on quantification of their dystonic involvement. Conventionally, this is attempted by clinical examination analysing the dystonic head position. In this presentation, a more systematic approach is sought by using an electromyography (EMG)-based evaluation procedure. In 10 consecutive patients with cervical dystonia not previously exposed to BT clinical examination, analysing the dystonic head position was performed to classify patients into four groups with similar dystonic head positions. Additionally, a 2-channel concentric needle EMG was used to measure the amplitudes of dystonic and maximal voluntary activities in sternocleidomastoid (SCM), splenius capitis (SC) and trapezius/semispinalis capitis (T/SS) muscles bilaterally. The ratio between both amplitudes, the dystonia ratio, was used to quantify dystonic muscle involvement. In all patients dystonia ratios could be calculated. In patients with similar head positions, EMG evaluation revealed different qualitative and quantitative dystonic involvement patterns. In six patients, there were discrepancies in identification of dystonic muscles between clinical examination and EMG evaluation. EMG evaluation excluded dystonic involvement in five patients. All excluded muscles were SCM. In one of these patients, additional T/SS involvement was detected by EMG evaluation. In one patient, SC involvement was revealed by EMG evaluation. All dystonic muscle involvement detected by EMG evaluation represented genuine dystonic muscle coactivation rather than compensatory muscle activity. The EMG evaluation presented allows quantitative and qualitative identification of dystonic muscle involvement which cannot be achieved by clinical examination. Both pieces of information may be helpful for optimization of BT therapy.     

Self-reported benefit and weakness after botulinum toxin in dystonia

With this retrospective, single center, chart review study, we investigate the self-reported benefit and weakness after botulinum toxin injections in three different types of dystonia: focal hand dystonia (FHD), blepharospasm and cervical dystonia. We found that the benefit lasts significantly longer in FHD compared to the other two groups.     

Adult-onset primary focal foot dystonia

Although primary focal hand dystonia has been well characterized, primary focal foot dystonia in adults has rarely been reported. Our objective was to describe the clinical phenotype and treatment outcomes in patients with primary, adult-onset focal foot dystonia. To this end we conducted a retrospective study of four consecutive patients (59.5+/-13.5 years, range 44-67) diagnosed over a period of 6 years and followed-up for at least 5 years. Focal foot dystonia resulted in variable physical impairment. Anti-dystonic agents were mildly effective whereas botulinum toxin injections provided substantial benefit when used. Focal primary focal foot dystonia seems to be a rare form of focal dystonia with distinct clinical features that may benefit from treatment with botulinum toxin.     

Coronoidotomy as treatment for trismus due to jaw-closing oromandibular dystonia.

Oromandibular dystonia is a focal dystonia involving the masticatory and/or tongue muscles. This report describes 2 female patients with jaw-closing dystonia treated by surgical resection of the coronoid process. The patients could not open their mouths due to involuntary jaw-closing muscle contraction. We first treated them by injecting lidocaine and alcohol (muscle afferent block) into the masseter and temporal muscles and then botulinum toxin. However, the trismus improved mildly and transitorily. Therefore, coronoidotomy was done under general anesthesia. The jaw opening increased to 50 mm. Coronoidotomy is useful for patients with jaw-closing dystonia in whom other therapies are ineffective.     

Cervical dystonia affects aimed movements of nondystonic segments

Patients with focal dystonia exhibit proprioception abnormalities that can lead to kinematic deficits. Proprioceptive abnormalities are present in both symptomatic and asymptomatic body parts of dystonic patients. To ascertain whether in patients with idiopathic cervical dystonia (CD) movements performed with nondystonic segments display kinematic abnormalities, we studied trajectory formation of out and back arm reaching movements in 10 patients with CD (before and 3 weeks after treatment with Botulinum toxin) and in 10 age‐matched controls. Before treatment, patients with CD showed significant trajectory abnormalities when compared with normal controls. Patients' trajectories were more curved with asymmetrical temporal velocity profiles as well as increased hand path areas, and had longer reversal lags between the out and back segments. Treatment with botulinum toxin improved all the kinematic parameters. These results suggest that in patients with CD, movements performed with nondystonic segments are abnormal. The kinematic abnormalities are likely to derive from long‐standing defective integration of the proprioceptive input, which, in turn, causes general changes in the internal models of limb dynamics. It is plausible that treatment with botulinum toxin partially restores proprioceptive processing and thus, such internal models. © 2009 Movement Disorder Society     

Cervical dystonia: Improved treatment response to botulinum toxin after referral to a tertiary centre and the use of polymyography

RationaleCervical dystonia is the most common form of (primary) dystonia. The first line of treatment for cervical dystonia is intramuscular injections with botulinum toxin. To optimise the response to botulinum toxin proper muscles selection is required. Pre-treatment polymyographic EMG in addition to clinical evaluation is hypothesised to be a good tool to improve muscle selection and treatment outcome.ObjectiveTo determine the efficacy of botulinum toxin treatment after adjacent polymyographic EMG in cervical dystonia patients referred to our tertiary referral centre with an unsatisfactory response to botulinum toxin treatment elsewhere.MethodsWe performed a retrospective analysis of 40 consecutive second opinion cervical dystonia patients. Standard polymyographic EMG was performed before treatment. We retrieved the Tsui scores and subjective evaluations from the first visit, after 12 weeks and after one year of treatment. In addition, we assessed the final outcome of treatment in our centre based on the records and asked the patients for their personal opinion about the effect of referral to our centre on their treatment response.ResultsAfter one year of treatment there was a significant improvement on both the Tsui scores (p < 0.01) and the subjective treatment evaluation (p < 0.001.) On their last visit 60% of the patients still continued treatment with a reasonable to good response.ConclusionA substantial amount of CD patients with an unsatisfactory response to botulinum toxin improved after polymyography and subsequent treatment with botulinum toxin in a tertiary referral centre.     

Cervical echomyography in cervical dystonia and its application to the monitoring for muscle afferent block (MAB)]

Muscle afferent block (MAB) is an intramuscular injection of 0.5% lidocaine and pure ethanol with a volume ratio of 10:1, introduced as an alternative to botulinum toxin injection for focal dystonia and spasticity. As in the case of botulinum toxin injection, the precise localization of target muscles is crucial to obtain the maximal effect from MAB. For this purpose, we performed ultrasonography of cervical muscles (echomyography) in 20 patients with cervical dystonia (11 men, 9 women; mean age 46.1), with ultrasonograph SSD-5500 (Aloca Co. Ltd., Japan) and a 7.5 MHz linear probe. In untreated subjects, the boundaries of muscles could be easily identified, while they tended to become ambiguous after repeated MAB sessions. At rest, there were involuntary worm-like movements of a specific muscle group observed in all patients. Contrary to our expectation, in all but one patient abnormal contraction was limited only in a part of synergists responsible for the abnormal posture. In normal subjects there was no abnormal contraction at rest, and all the synergists were simultaneously activated by the voluntary neck deviation. Normal subjects could not mimick the pattern of muscle activity in dystonic patients. The echo-guided MAB was performed in 16 patients. We could easily observe the diffusion of lidocaine and ethanol into the targeted muscle, and injected portions of the muscle stopped their activities just after MAB. The effect persisted for 3-4 days in at least 5 out of 10 patients who had follow-up examination. On the other hand, the movement stopped only temporarily after the injection of saline or lidocaine only. In 3 out of 16 patients, some of the uninjected synergists were activated as if to substitute for the treated muscle just after the injection. We conclude that cervical echomyography is useful to investigate the pattern of muscle activity in cervical dystonia and to accurately localize the contracting muscles during MAB.     

Elimination of dysphagia using ultrasound guidance for botulinum toxin injections in cervical dystonia

Introduction: Dysphagia is a common side effect after botulinum toxin injections for cervical dystonia, with an incidence of 10–40%, depending upon the study and dose used. Methods: Our study consisted of 5 preselected women who met criteria for cervical dystonia and subsequent dysphagia after electromyography (EMG)‐guided injections. Injections were performed with ultrasound (US) imaging, and the effects on swallowing were examined. Separately, sternocleidomastoid (SCM) thickness in healthy controls and treated patients was measured. Results: There were 34 episodes of dysphagia over 98 injection sessions using EMG guidance for a cumulative rate of 34.7%. Using US plus EMG guidance, there was 0% dysphagia across 27 injection sessions. SCM thickness was <1.1 cm. Conclusion: US combined with EMG guidance eliminated recurrent dysphagia after botulinum toxin treatment, possibly by keeping the injectate within the SCM. Muscle Nerve 46: 535–539, 2012