Regional cerebral blood flow correlates of the severity of writer's cramp symptoms

Writer's cramp is a type of idiopathic focal dystonia with incompletely understood pathophysiology. Recent studies provide evidence that one element might be a sensory processing defect. We performed a PET study with O(15) H(2)O to find out in which brain areas activity correlates with the severity of writer's cramp symptoms. METHODS: We studied 10 patients with writer's cramp and 10 age- and gender-matched control subjects. There were seven conditions, each repeated twice: rest, writing, tapping with index finger for 2, 3, 4, and 5 min. For each scan, we obtained EMG recordings from the flexor digitorum superficialis (FDS), extensor indicis proprius (EIP) muscles, and a subjective score of severity of dystonia. Scans were realigned, normalized, smoothed, and analyzed using SPM99. Analysis included both intra- and intergroup comparisons and a correlation analysis where we used EMG recordings and subjective dystonia score as covariates. RESULTS: Random effect analysis of the writing task showed overactivity of the primary sensory cortex and no significant underactivity. Correlation analysis of dystonia patients showed activation of SI when we used the subjective dystonia score as a covariate, and activation of both the SI and primary motor cortex when the normalized EMG score of FDS was used. CONCLUSION: While some overactivity of MI is not surprising, overactivity of SI is more dramatic and suggests a primary deficit in processing sensory feedback. Writer's cramp may arise in part as a dysfunction of sensory circuits, which causes defective sensorimotor integration resulting in co-contractions of muscles and overflow phenomena.     

Task-specific plasticity of somatosensory cortex in patients with writer's cramp

Focal dystonias such as writer's cramp are characterized by muscular cramps that accompany the execution of specific motor tasks. Until now, the pathophysiology of focal dystonia remains incompletely understood. Recent studies suggest that the development of writer's cramp is related to abnormal organization of primary somatosensory cortex (SI), which in turn leads to impaired motor function. To explore contributions of SI on mechanisms of task specificity in focal dystonia, we investigated dynamic alterations in the functional organization of SI as well as sensory-motor gating for rest, left- and right-handed writing and brushing in writer's cramp patients and healthy controls. The functional organization of somatosensory cortex was assessed by neuromagnetic source imaging (151 channel whole-head MEG). In accordance with previous reports, distances between cortical representations of thumb and little finger of the affected hand were smaller in patients compared to healthy subjects. However, similar to healthy controls, patients showed normal modulation of the functional organization of SI as induced by the execution of different motor tasks. Both in the control subjects and patients, cortical distances between representations of thumb and little finger increased when writing and brushing compared to the resting condition. Although, cramps only occured during writing, no differences in the organization of SI were seen among motor tasks. Our data suggest that despite alterations in the organization of primary somatosensory cortex in writer's cramp, the capability of SI to adapt dynamically to different tasks is not impaired.     

Treatment of cervical dystonia and focal hand dystonia by high cervical continuously infused intrathecal baclofen: a report of 2 cases

We describe 2 patients, one with cervical dystonia (CD) combined with focal hand dystonia (writer's cramp) and another with idiopathic CD, who were unresponsive to oral medications and became resistant to botulinum toxin type A and B injections. Both patients were successfully treated with high cervical (C1-3) continuously infused intrathecal baclofen (ITB). Neck range of motion (ROM) was measured by using a 3-dimensional electromagnetic cervical ROM system. Pain, disability, and severity were assessed by using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). The patient with CD and writer's cramp did well on a continuous baclofen dose of 186.1 microg/d. Her total TWSTRS score improved significantly, her electromagnetic measurements showed an increased in total neck flexion and extension, and her handwriting improved. Unfortunately, this patient (a heavy smoker) developed small cell carcinoma of the lung and died 9 months after her pump was placed. Total TWSTRS score and electromagnetic measurements also significantly improved after pump implant in the patient with CD. He continues to do well on a periodic bolus dose using a combination of 50 microg of baclofen and 25 microg of hydromorphone (Dilaudid) every 4 hours. Our findings suggest the potential usefulness of this therapy in other patients with focal dystonia. To our knowledge, this is the first reported successful treatment of CD and CD combined with writer's cramp with high cervical continuously infused ITB.     

Treatment of focal dystonia with botulinum toxin A

Local injections with Botulinum toxin A (BtxA) are safe and effective in the treatment of focal dystonia. In cervical dystonia and blepharospasm, BtxA injections have become the treatment of choice. However, good results have also been reported with oromandibular dystonia, spasmodic dysphonia and writer's cramp. In cervical dystonia, muscles for injection are selected by clinical presentation or in complex forms with EMG guidance. Several studies have shown that 500 units Dysport are safe and effective in the treatment of cervical dystonia. In blepharospasm, injections are performed in the periorbital part of the orbicularis oculi muscle with good results for 12-14 weeks. The most frequently employed starting dose is 120 units Dysport per eye, divided in three periorbital injection sites. In case of levator inhibition, the pretarsal part of the orbicularis oculi muscle should be injected in a lower dose. EMG guidance is not necessary. By contrast, BtxA treatment of spasmodic dysphonia and writer's cramp require EMG-guided injections in order to avoid side-effects. Dose recommendations for the various types of dystonia are given in the text. In up to 5% of patients with dystonia, the development of neutralising antibodies is reported following repetitive injections with BtxA. Patients with antibodies had a shorter interval between injections, more "boosters", a higher dose per 3-month interval, and a higher total dose injected. In case of neutralizing antibodies against the A toxin, the treatment with Botulinum toxin B (Neurobloc) is a possible alternative.     

Restoring balance in focal limb dystonia with botulinum toxin

Focal task-specific dystonia of the hand is rare in the general population, where it usually manifests as writer's cramp, but seems relatively common among musicians. The disability may be so severe as to prevent writing altogether or to end a professional musician's career. The cause is usually unknown but it is thought to be primarily a basal ganglia disorder with dysfunction of cortical-striatothalamic-cortical circuits. Abnormalities have been found in cortical movement preparation, intracortical inhibition, sensory and motor maps, and patterns of cortical activation during movement. Much evidence supports disordered processing of sensory information with disturbed sensorimotor integration. Underlying this may be maladaptive neural plasticity mechanisms. Treatment is difficult. Oral medications are generally ineffective and have troublesome side-effects. Intensive rehabilitation techniques based on neural plasticity theory show promise but are rarely available and are time-intensive. Botulinum toxin injections appear to be effective in writer's cramp and musician's dystonia, at least initially; long-term benefit is less common. Despite definite improvement, some patients abandon treatment because the gain is insufficient for meaningful function: this is particularly so for musicians. Much of the benefit from botulinum toxin injection comes from simply reducing muscle overactivity through muscle paralysis, restoring balance to motor control. However, some evidence suggests that botulinum toxin injections can produce transient improvement in some of the various cortical abnormalities described, probably through alteration of sensory input from the periphery, by direct and indirect means. These changes in cortical function might be usefully combined with those brought about by sensorimotor retraining programs, but such studies are awaited.     

Movement disorders and botulinum toxin in neurology

Botulinum toxin has been a useful treatment in many movement disorders and more recently in other non-neurological motor dysfunctions for more than 15 years. Here, we review the various indications in neurology, mainly in the field of movement disorders. From 1973 to 2002, we searched the Medline database on this topic. We selected the most useful and relevant papers, with a special interest in dystonia. We summarized the results in the main indications (spasmodic torticollis, bleparospasm, hemifacial spasm) and in other manifestations such as writer's cramp, oromandibular dystonia, tremor, tics and myoclonus. We discuss the data of literature and compare them with the experience of the French movement disorders groups.     

书写痉挛责任肌群的认定及肉毒毒素治疗的疗效观察

目的　寻找引起患者书写痉挛 (writer scramp)并导致字迹抖动不清的主要责任肌群 ,并同时观察局部注射肉毒毒素 A (botulinumtoxin A ,BTX A)对书写痉挛病症的治疗效果及副反应发生情况。方法　通过对前臂肌群的选择性运动 ,判断各肌群对书写痉挛症状的影响 ,并初步认定责任肌群 ,然后用维库溴铵对初步确定的责任肌群进行选择性注射 ,以进一步确定引起书写痉挛的主要责任肌群 ,最后对已确定的主要责任肌群进行BTX A多点注射 ,观察其疗效及副反应发生情况。结果　本研究发现 ,当前臂旋转肌群运动时会加重书写痉挛症状 ,对该群肌肉注射维库溴铵后可消除痉挛症状。当对旋转肌群进行BTX A注射后 ,受试的 3例患者 (共 5侧患肢 )症状全部得到改善 ,无一例发生可察觉的握力减退及垂腕等副反应。结论　前臂旋转肌群是导致书写痉挛并致使字迹抖动不清的主要责任肌群 ,对其进行BTX A选择性多点注射可获得满意疗效 ,同时还可避免握力减退及垂腕等副反应的发生。     

Elevated beta-N-acetylhexosaminidase activity in focal dystonia fibroblasts.

Specific activities of beta-D-hexosaminidase, alpha-D-mannosidase, beta-D-galactosidase and beta-D-glucuronidase were determined in fibroblasts of patients with writer's cramp and torticollis. These diseases show degenerative neurological disorders similar to those observed in lysosomal diseases. Hexosaminidase specific activities, determined using 4-methylumbelliferyl-beta-N-acetylglucopyranoside and 4-methylumbelliferyl-beta-N-acetylglucopyranoside-6-sulphate as substrates, were significantly higher in the fibroblasts of patients than in controls. No significant differences were observed in the specific activities of the other lysosomal enzymes. The increased hexosaminidase specific activities in torticollis and writer's cramp may be additional markers for these diseases.     

Electroencephalographic spectral power in writer's cramp patients: evidence for motor cortex malfunctioning during the cramp

We investigated cortical activation as reflected in task-related spectral power (TRPow) changes in 8 writer's cramp patients during writing on a digital board and during isometric contraction and compared them to those of 8 age-matched healthy subjects. Scalp EEG was recorded over the contralateral primary sensorimotor area (SM1(c)), and from the ipsilateral sensorimotor area (SM1(i)). The electromyogram (EMG) was recorded from the Extensor Digitorum Communis (Extensor), Flexor Digitorum Superficialis (Flexor), and First Dorsal Interosseous (FDI) muscles. We analyzed (1) handwriting performance, (2) changes in the TRPow confined to alpha and beta band, and (3) the EMG spectral power during both tasks, writing and isometric contraction. During writing, all patients developed writer's cramp. The handwriting in writer's cramp patients was associated with significantly less reduction of the beta-range TRPow and lower frequency of the TRPow reduction compared to controls. No significant differences between patients and controls for the alpha band TRPow reduction during handwriting were observed. During writing, the patients showed higher EMG spectral power than the controls but this difference was at the border of significance. The present results indicate disorder in the motor execution system, in writer's cramp patients, associated with impaired functional beta-network state of the contra- and ipsilateral sensorimotor cortices, most probably due to inadequate modulation of the intracortical inhibition associated with writing.     

Restoring balance in focal limb dystonia with botulinum toxin

Focal task-specific dystonia of the hand is rare in the general population, where it usually manifests as writer's cramp, but seems relatively common among musicians. The disability may be so severe as to prevent writing altogether or to end a professional musician's career. The cause is usually unknown but it is thought to be primarily a basal ganglia disorder with dysfunction of cortical-striatothalamic-cortical circuits. Abnormalities have been found in cortical movement preparation, intracortical inhibition, sensory and motor maps, and patterns of cortical activation during movement. Much evidence supports disordered processing of sensory information with disturbed sensorimotor integration. Underlying this may be maladaptive neural plasticity mechanisms. Treatment is difficult. Oral medications are generally ineffective and have troublesome side-effects. Intensive rehabilitation techniques based on neural plasticity theory show promise but are rarely available and are time-intensive. Botulinum toxin injections appear to be effective in writer's cramp and musician's dystonia, at least initially; long-term benefit is less common. Despite definite improvement, some patients abandon treatment because the gain is insufficient for meaningful function: this is particularly so for musicians. Much of the benefit from botulinum toxin injection comes from simply reducing muscle overactivity through muscle paralysis, restoring balance to motor control. However, some evidence suggests that botulinum toxin injections can produce transient improvement in some of the various cortical abnormalities described, probably through alteration of sensory input from the periphery, by direct and indirect means. These changes in cortical function might be usefully combined with those brought about by sensorimotor retraining programs, but such studies are awaited.     

Application of botulinum toxin to clinical therapy: advances and cautions

The therapeutic use of botulinum toxin Type A has followed a novel and unanticipated pathway of applications, from its initial application by Scott to paralyze the extraocular muscles of the eyes to correct strabismus. In the late 1970s, Scott formed a company, called Oculinum Inc, to make botulinum toxin Type A available for this ophthalmic application. From this modest and limited beginning, it has found use for treatment of a plethora of cosmetic, neuromuscular, and skeletal disabilities, including cervical dystonia, blepharospasm, and temporary improvement in the appearance of moderate to severe glabellar lines. Botulinum toxin Type A is now being used as therapy in voiding disorders, migraine and tension-type headache, writer's cramp, and laryngeal muscle hyperactivity syndromes. It has reduced the spasm and pain associated with perianal fissures. It has found application in the reduction of glandular function in severe primary axillary hyperhidrosis and sialorrhea. Additional applications are being studied in the area of pain management based on its apparent ability to inhibit neuropeptide release from nociceptors.     

Focal dystonia in musicians

In conclusion, musicians' focal dystonia is a significant and potentially career-ending neurological condition of which physiatrists and other performing arts medicine clinicians should be aware. Pathology has been identified in the somatosensory cortex, and in the motor cortex and basal ganglia. Although advances have been made in the elucidating some of the pathologic changes in focal dystonia, better understanding is needed. Current treatments such as retraining, splinting, oral medications, and botulinum toxin injections are limited. Therefore, the ultimate goal for focal dystonia is to prevent this disabling disorder of instrumental musicians.     

Use of botulinum toxin type A in neuro-ORL]

Dystonia is the result of abnormal contractions of muscles, which may disturb activities between agonist and antagonist muscles. Since synchronization of laryngeal and masticatory muscles is highly necessary to allow opening and closure of the larynx or the mouth, expression of dystonia is especially exhibited. Focal laryngeal dystonia may disturb phonation, but also breathing or swallowing, which may be difficult to identify. In ORL, the botulinum toxin is used to treat focal dystonias, especially laryngeal (spamodic dysphonia being predominant) and oromandibular dystonias. Beside these indications, intracutaneous injections of botulinum toxin may be helpful in Frey's syndrome in patients with gustatory sweating; injections in the upper esophageal sphincter are also performed in cricopharyngeal dysphagia although this indication is mainly controversial.     

Cervical dystonia: disease profile and clinical management

Cervical dystonia, the most common focal dystonia, frequently results in cervical pain and disability as well as impairments affecting postural control. The predominant treatment for cervical dystonia is provided by physicians, and treatment can vary from pharmacological to surgical. Little literature examining more conservative approaches, such as physical therapy, exists. This article reviews the etiology and pathophysiology of the disease as well as medical and physical therapist management for people with cervical dystonia.     

Effects of Modified Pen Grip and Handwriting Training on Writer's Cramp

Baur B, Fürholzer W, Jasper I, Marquardt C, Hermsdörfer J. Effects of modified pen grip and handwriting training on writer's cramp.

Objective

To evaluate the use of a modified pen grip and subsequent handwriting training in patients with writer's cramp (WC).

Design

Handwriting performance with normal and modified pen grip was examined once in healthy controls and repeatedly in patients with WC (2 baseline tests before training, directly after training, after a 3-month follow-up).

Setting

Ambulatory care for motor writing disorders.

Participants

Patients with WC (n=26) and healthy controls (n=14).

Intervention

Seven sessions of handwriting training with various motor exercises were conducted by an occupational therapist. During training, the patients always used a modified pen grip (stabilized between index and middle finger).

Main Outcome Measures

Writing frequency and fluency, grip force on the pen, writing pressure, Fahn dystonia scale, visual analog scales for impairment and pain.

Results

Patients with WC showed increased writing pressure and grip force before training. Using the modified pen grip caused in both patients with WC and controls a decrease in pressure and grip force. Handwriting training resulted in a further improvement of both parameters in patients with WC. Grip force reduction remained stable over follow-up.

Conclusions

Results suggest that patients with WC benefit from the use of the modified pen grip in combination with handwriting training.     

Use of chemodenervation in dystonic conditions

Dystonia, an uncommon movement disorder that causes sustained muscle contractions and painful body positions, is a difficult diagnostic challenge; misdiagnosis is common. Classification may include etiology, area of physical involvement, or age of onset. Bodily distribution is varied, and dystonias can present as primary (genetic) or secondary (caused by other disease processes or use of neuroleptic drugs). Although there is no cure, the use of botulinum toxins for chemodenervation provides symptomatic relief and is considered the treatment of choice in focal dystonia. The dose of botulinum toxin may be titrated to provide significant relief for 12 weeks or more.     

Focal dystonia following soft tissue injury: three case reports with long-term outcome

Three cases of focal dystonia are described which followed upper extremity injuries. Each patient developed a dystonic posturing in that limb; two patients improved when their initial condition was addressed. Various authors have proposed that focal dystonia represents a limited form of generalized dystonia, which is believed to result from a disturbance of striatopallidal-thalamic input to the supplementary motor area (SMA)--a vital executive area for motor control. An alternative hypothesis is offered; that is, a similar dysfunction of the SMA could be the result of altered sensory information from a painful limb disturbing the crucial integration between sensory input and motor performance. The following three examples of such integration are provided: (1) the long loop or transcortical reflex, (2) input of distinctive somatosensory neurons to the SMA, and (3) the projection of proprioceptive and tactile sensory input into peripheral receptive fields of the motor cortex.     

Structural, functional and molecular imaging of the brain in primary focal dystonia--a review

Primary focal dystonias form a group of neurological disorders characterized by involuntary, sustained muscle contractions causing twisting movements and abnormal postures. The estimated incidence is 12-25 per 100,000. The pathophysiology is largely unclear but genetic and environmental influences are suspected. Over the last decade neuroimaging techniques have been applied in patients with focal dystonia. Using structural, functional and molecular imaging techniques, abnormalities have been detected mainly in the sensorimotor cortex, basal ganglia and cerebellum. The shared anatomical localisations in different forms of focal dystonia support the hypothesis of a common causative mechanism. The primary defect in focal dystonia is hypothesised in the motor circuit connecting the cortex, basal ganglia, and cerebellum. Imaging techniques have clearly enhanced current knowledge on the pathophysiology of primary focal dystonia and will continue to do so in the future.     

Botulinum toxin A in the management of focal muscle overactivity in children with cerebral palsy

Cerebral palsy comprises a heterogenous group of neurological disorders representing a continuum of pathologies and clinical phenotypes. Although cerebral palsy is not a focal disorder, it is appropriate to treat identified focal problems as long as the intervention is goal directed. This paper reviews principles of managing muscle imbalance in the growing, changing child using a range of complementary, carefully timed intervention options. Over the past two decades these options have increasingly included intramuscular injection of botulinum toxin-A to manage focal spasticity and dystonia. The predictable movement patterns and postures characteristic of spasticity enable a systematic clinical rationale to be developed to determine the role of botulinum toxin-A to manage the spasticity and subsequently improve function. The management of dystonia with botulinum toxin-A is more complex, particularly when spasticity and dystonia are present in combination. An active therapy programme remains central to the management of movement problems in the child with cerebral palsy, including task-specific motor training, maintenance of muscle lengths, and improved muscle strength, aiming to achieve carry over improvements that persist beyond the pharmacological effects of the botulinum toxin-A. A series of case examples are presented to highlight the role of botulinum toxin-A in the overall management of the child with focal muscle hyperactivity.     

Botulinum toxin therapy for neurologic disorders.

In the last 20 years, the therapeutic uses of botulinum toxin, a potent neurotoxin, have been investigated. The agent produces chemical denervation of muscle, thereby causing atrophy and weakness. Studies have shown that injection of this agent is an effective therapy for focal dystonias, particularly blepharospasm, hemifacial spasm, and torticollis. Investigation continues into the role of botulinum toxin in the treatment of anismus, detrusor-sphincter dyssynergia, writers' cramp, and other disorders in which focal weakening of selected muscles could be useful.