Does the guidance method affect the doses of botulinum toxin in writer's cramp?

PURPOSE

Botulinum neurotoxin (BoNT) injections are the main medical treatment of writer's cramp. When the outcome is favourable, patients usually receive injections several times per year in the long-term. However, we know little about the course of BoNT doses and nothing about the impact of the guidance method on the clinical outcome or injection strategy.

METHODS

We studied, in the long-term, the doses of BoNT and the target muscles in a group of patients with writer's cramp, according to the guidance method (electrical stimulation or ultrasound). Patients received at least three injection cycles guided by electrical stimulation, followed by at least three injection cycles guided by ultrasound.

RESULTS

Twenty-four patients were included. More target muscles were injected after switching to ultrasound guidance, especially the flexor carpi ulnaris and the flexor carpi radialis. The mean dose by muscle was lower when ultrasound guidance was used. When using electrical stimulation guidance, the dose in the flexors of the fingers decreased in the long-term, but increased in the flexors of the wrist. The course of the BoNT doses and of the number of target muscles per cycle were not the same during the first period (electrical stimulation) and the second period (ultrasound).

CONCLUSIONS

Switching to ultrasound guidance, the BoNT dose decreased, mainly in the flexors of the wrist. Based on the results of our study, we suggest a starting dose in several muscles (flexor carpi ulnaris, flexor carpi radialis, flexor digitorum profundus and flexor pollicis longus).

Comprehensive analysis of non-motor symptoms and their association with quality of life in Writer's cramp

OBJECTIVE

Limited studies have focused on non-motor symptoms (NMS) in patients with Writer's cramp (WC). The current study aimed to examine the frequency of NMS and their association with health-related quality of life (HR-QoL) in patients with WC.

METHODS

A total of 80 patients with WC and 69 healthy controls (HCs) were enrolled. Motor symptoms was assessed by Burke-Fahn-Marsden dystonia rating scale and NMS was evaluated through several specific scales, including Hamilton depression rating scale-24 items (HDRS-24), Hamilton anxiety rating scale, Epworth sleepiness scale, Pittsburgh sleep quality index, fatigue severity scale (FSS), numerical rating scale for pain, and Montreal cognitive assessment. The HR-QoL was assessed using 36-item short form health survey (SF-36), which can be divided into physical component summary (PCS) and mental component summary (MCS). Multiple linear regression was used to analysis the association between each NMS and HR-QoL.

RESULTS

The patients presented more symptoms of depression, anxiety, poor quality of sleep, excessive daytime sleepiness, and fatigue than the HCs. The most frequent NMS in patients with WC was anxiety (51.25%) and depression (46.25%) symptoms. We found that motor symptoms had no association with HR-QoL. Higher scores of HDRS-24 were associated with lower scores of SF-36 in PCS and MCS. Meantime, higher scores of FSS were significantly associated with lower scores of SF-36 in MCS.

CONCLUSION

The NMS was prevalent in patients with WC, with frequent anxiety and depression symptoms. Depression symptoms and fatigue had a strongly negative impact on HR-QoL and deserve attention in clinic practice.

Investigating DYT1 in a Taiwanese dystonia cohort

BACKGROUND/PURPOSE

A heterozygous three-nucleotide (GAG) in-frame deletion in the TOR1A gene causes the rare disease, dystonia (DYT1), which typically presents as focal limb dystonia during adolescence, then spreads to other limbs. This study investigated the frequency and clinical features of DYT1 in a Taiwanese dystonia cohort.

METHODS

We performed targeted next generation sequencing in 318 patients with primary dystonia. We identified one DYT1 family with various types of dystonia, and we described the clinical presentations observed in this family during a 30-year follow-up. We compared the clinical characteristics to those reported in previous studies on DYT1 from 2000 to 2020.

RESULTS

Among 318 patients, we identified only one DYT1 patient (0.3%) with an autosomal dominant family history of dystonia. The proband was a 43-year-old man that experienced progressive onset of focal lower limb dystonia from age 11 years. The disease spread caudal-rostrally to the upper limbs and cervical muscles. Prominent cervical dystonia was noted during follow-up, which was an atypical presentation of DYT1. Clinical assessments of other family members showed intrafamily variability. The proband's father and an affected sibling demonstrated only mild right-hand writer's cramp. A systematic review of previously reported DTY1 cases showed that Asian patients had a higher frequency of cervical dystonia (44.8%) than groups of Ashkenazi Jews (35%) and Non-Jewish Caucasians (30.5%) (P = 0.04).

CONCLUSION

Our findings revealed that DYT1 is rare in a Taiwanese dystonia cohort. The presentation of marked cervical dystonia could be the main feature of Asian patients with DYT1.

Botulinum toxin dosing in arm muscles: contextual factors

Botulinum toxin (BT) has been successfully used for many years to treat various muscle hyperactivity disorders including dystonia and spasticity. Its dosing is guided by dosing tables describing target muscles and dose ranges. To refine the BT dosing, we wanted to analyse how contextual factors may influence the injector's final dosing decision.

In a retrospective review of real-life data of 1170 BT treatments, we studied the influence of various contextual factors on the BT doses in 21 arm muscles of 252 patients receiving BT therapy for different muscle hyperactivity disorders.

We found that BT arm doses are significantly higher in treatment of spasticity than in treatment of dystonia. We also found that spontaneous arm dystonia requires higher BT doses in a proximal application pattern, whereas task specific writer's cramp requires considerably reduced BT doses with a distal application pattern. Injections of non-arm muscles influence the BT dosing in arm muscles only marginally.

Our study demonstrates that BT dosing does not only depend on the particularities of the individual target muscle injected, such as its volume and its static or phasic function. BT dosing and its application pattern rather depend on additional contextual factors such as the aetiology and pathophysiology of the muscle hyperactivity treated. These contextual factors need to be included in dosing tables and may improve the outcome of BT therapy.

Botulinum toxin and occupational therapy for Writer's cramp

BACKGROUND

Writer's cramp (WC) is a form of focal hand dystonia, for which focal botulinum neurotoxin (BoNT) injections are the current best therapy. Past studies have shown that some types of rehabilitative therapy can be useful. We hypothesized that BoNT together with a specific type of occupational therapy would be better than BoNT alone for treating WC patients comparing the effects with a patient-rated subjective scale.

METHODS

Twelve WC patients were randomized to two groups. Six received only BoNT therapy and 6 received BoNT & occupational therapy. The occupational therapy involved specific exercises of finger movements in the direction opposite to the dystonic movements during writing. BoNT was injected by movement disorders neurologists in the affected muscles under electromyography-guidance. The primary outcome was the patient-rated subjective scale at 20 weeks. Secondary exploratory outcomes included the writer's cramp rating scale (WCRS), writer's cramp impairment scale (WCIS), the writer's cramp disability scale (WCDS), handgrip strength and kinetic parameters.

RESULTS

The patient-rated subjective scale scores at 20 weeks were not significantly different between the two groups. Significant objective improvement was noted in the BoNT & occupational therapy group, as noted by the decrease (28%) in WCIS scores.

CONCLUSIONS

Improvement of the primary outcome measure, the patient-rated subjective scale, was not achieved. However, significant improvement was found in the BoNT & occupational therapy group in a secondary measure of impairment. Our hypothesis-driven study results are likely limited by small sample size, and further large-scale studies of occupational therapy methods to improve the efficacy of BoNT seems worthwhile.

Improvement of Writer's Cramp from an Old Lesion in the Contralateral Hemisphere with Transient Gait Disturbance After Thalamotomy

BACKGROUND

Stereotactic ventro-oral thalamotomy has been performed in cases of focal task-specific dystonia, including writer's cramp, with excellent outcomes. However, no reports have revealed the outcome of ventro-oral thalamotomy in a patient with a contralateral cerebral lesion. We describe a patient with left-hand writer's cramp with an old lesion in the left hemisphere and transient gait disturbance after right ventro-oral thalamotomy.

CASE DESCRIPTION

A 43-year-old man had a hemorrhage in the left basal ganglia due to cerebral arteriovenous malformation at 22 years of age, and right hemiparesis remained as a sequela. He developed left-handed writing ability; however, he became aware of the stiffness of his left hand and difficulty in writing. Writer's cramp was diagnosed. Medical treatments were not effective, and right ventro-oral thalamotomy was performed. Although his writing ability improved, he could not walk. After performing rehabilitation, his walking completely improved, reaching the level before surgery, after 3 months, and his writer's cramp was completely cured.

CONCLUSIONS

In patients with basal nucleus lesions, gait disturbance may appear transiently after contralateral thalamotomy. It is crucial to fully explain the potential complications, particularly in relation to temporal gait disturbances, and obtain informed consent.

Dynamic causal modeling revealed dysfunctional effective connectivity in both, the cortico-basal-ganglia and the cerebello-cortical motor network in writers' cramp

Writer's cramp (WC) is a focal task-specific dystonia characterized by sustained or intermittent muscle contractions while writing, particularly with the dominant hand. Since structural lesions rarely cause WC, it has been assumed that the disease might be caused by a functional maladaptation within the sensory-motor system. Therefore, our objective was to examine the differences between patients suffering from WC and a healthy control (HC) group with regard to the effective connectivity that describes causal influences one brain region exerts over another within the motor network. The effective connectivity within a network including contralateral motor cortex (M1), supplementary motor area (SMA), globus pallidus (GP), putamen (PU) and ipsilateral cerebellum (CB) was investigated using dynamic causal modeling (DCM) for fMRI. Eight connectivity models of functional motor systems were compared. Fifteen WC patients and 18 age-matched HC performed a sequential, five-element finger-tapping task with the non-dominant and non-affected left hand within a 3 T MRI-scanner as quickly and accurately as possible. The task was conducted in a fixed block design repeated 15 times and included 30 s of tapping followed by 30 s of rest. DCM identified the same model in WC and HC as superior for reflecting basal ganglia and cerebellar motor circuits of healthy subjects. The M1-PU, as well as M1-CB connectivity, was more strongly influenced by tapping in WC, but the intracortical M1-SMA connection was more facilitating in controls. Inhibiting influences originating from GP to M1 were stronger in controls compared to WC patients whereby facilitating influences the PU exerts over CB and CB exerts over M1 were not as strong. Although the same model structure explains the given data best, DCM confirms previous research demonstrating a malfunction in effective connectivity intracortically (M1-SMA) and in the cortico-basal ganglia circuitry in WC. In addition, DCM analysis demonstrates abnormal reciprocal excitatory connectivity in the cortico-cerebellar circuitry. These results highlight the dysfunctional cerebello-cortical as well as basalganglio-cortical interaction in WC.

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Effective connectivity in writer`s cramp differs under sequential finger movements.

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We found a deficient inhibitory pallido-cortical connectivity in writer`s cramp.

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We found a diverging effective connectivity in the cortico-cerebellar loop.

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We found a diverging effective connectivity in the cortico-basal ganglia pathway.

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Pathophysiological interaction between the cerebellum and the basal ganglia.

Focal task specific dystonia: a review and update

In this review, we summarize recent advances in understanding the etiology, risk factors and pathophysiology of focal task specific dystonia (FTSD), movement disorders characterized by abnormal motor activation during the performance of specific, repetitive actions. We focus on two common FTSD, musician’s dystonia and writer’s cramp. FTSD may pose a threat to the patient’s livelihood, and improved therapeutic treatments are needed.

Writer's cramp in spinocerebellar ataxia Type 1

Dystonia can be encountered in a small subset of patients with spinocerebellar ataxia (SCA), but task specific dystonia is extremely rare. We report a case of a 48-year-old male with confirmed SCA Type 1 (SCA1) with mild progressive cerebellar ataxia and a prominent and disabling Writer's cramp. This case highlights the ever-expanding phenotypic heterogeneity of the SCA's in general and SCA1 in particular.

Differences in active range of motion measurements in the upper extremity of patients with writer's cramp compared with healthy controls

STUDY DESIGN

Exploratory case-control study.

INTRODUCTION

Writer's cramp (WC) is a type of focal hand dystonia. The central nervous system plays a role in its pathophysiology, but abnormalities in the affected musculoskeletal components may also be relevant.

PURPOSE OF THE STUDY

We compared the active range of motion (ROM) in patients with WC and healthy volunteers (HVs) and correlated the findings with disease duration and severity.

METHODS

Affected limb joints were measured with goniometers. Patients were assessed at least 3 months after their last botulinum toxin (botulinum neurotoxin) injection, and strength was clinically normal. t tests were used to compare the ROMs of WC with matched HVs. The Spearman correlation coefficient assessed the relationship of active ROMs to the disease duration and handwriting subscore of the Dystonia Disability Scale.

RESULTS

ROMs of D1 metacarpophalangeal (MCP) joint extension as well as D2 and D5 MCP flexion were significantly smaller in WC, and distal interphalangeal joint extension in D3 and D5 was significantly greater compared with HVs. There were negative correlations between D2 MCP flexion and disease duration and with Dystonia Disability Scale.

DISCUSSION

Abnormalities in ROMs in WC were found. Severity and disease duration correlated with reduced D2 MCP flexion. This may be related to intrinsic biomechanical abnormalities, co-contraction of muscles, or a combination of subclinical weakness and atrophy from repeated botulinum neurotoxin injections.

CONCLUSIONS

Hand biomechanical properties should not be ignored in the pathophysiology of WC.

LEVEL OF EVIDENCE

2c.

Altered brain activation in a reversal learning task unmasks adaptive changes in cognitive control in writer's cramp

Previous receptor binding studies suggest dopamine function is altered in the basal ganglia circuitry in task-specific dystonia, a condition characterized by contraction of agonist and antagonist muscles while performing specific tasks. Dopamine plays a role in reward-based learning. Using fMRI, this study compared 31 right-handed writer's cramp patients to 35 controls in reward-based learning of a probabilistic reversal-learning task. All subjects chose between two stimuli and indicated their response with their left or right index finger. One stimulus response was rewarded 80%, the other 20%. After contingencies reversal, the second stimulus response was rewarded in 80%. We further linked the DRD2/ANKK1-TaqIa polymorphism, which is associated with 30% reduction of the striatal dopamine receptor density with reward-based learning and assumed impaired reversal learning in A + subjects. Feedback learning in patients was normal. Blood-oxygen level dependent (BOLD) signal in controls increased with negative feedback in the insula, rostral cingulate cortex, middle frontal gyrus and parietal cortex (pFWE < 0.05). In comparison to controls, patients showed greater increase in BOLD activity following negative feedback in the dorsal anterior cingulate cortex (BA32). The genetic status was not correlated with the BOLD activity. The Brodmann area 32 (BA32) is part of the dorsal anterior cingulate cortex (dACC) that plays an important role in coordinating and integrating information to guide behavior and in reward-based learning. The dACC is connected with the basal ganglia-thalamo-loop modulated by dopaminergic signaling. This finding suggests disturbed integration of reinforcement history in decision making and implicate that the reward system might contribute to the pathogenesis in writer's cramp.

Thalamic Deep Brain Stimulation for Writer's Cramp

Writer's cramp is a type of idiopathic focal hand dystonia characterized by muscle cramps that accompany execution of the writing task specifically. There has been renewed interest in neurosurgical procedures for the treatment of dystonia over the past several years. In particular, deep brain stimulation (DBS) has received increasing attention as a therapeutic option for patients with dystonia. However, to date, limited reporters made investigations into DBS in relation to the Writer's cramp. In this case, unilateral Ventro-oralis complex (Vo) DBS resulted in a major improvement in patient's focal dystonic movement disorders. Her post-operative Burke-Fahn-Marsden Dystonia Rating (BFMDR) scale demonstrated 1 compared with pre-operative BFMDR scale 4. We conclude that thalamic Vo complex DBS may be an important neurosurgical therapeutic option for Writer's cramp.

The sensory consequences of repetitive strain injury in musicians: focal dystonia of the hand

Some individuals with repetitive strain injury (RSI) develop focal dystonia of the hand (FDh), a disorder of motor control manifested in a specific context during skilled, hand movements. This descriptive study was designed to determine if musicians with FDh had reduced tactile discrimination. Ten healthy adults and ten patients with FDh participated in the study. From the standardized Sensory Integration and Praxis Test, five subtests were selected to measure tactile discrimination. The Paired Wilcoxon Test was used to analyze, meaningful, planned pairwise differences by side and by group. The two groups performed similarly on the three tests measuring tactile motor perception (Finger Identification, Localization and Kinesthesia). However, those with FDh performed significantly worse than the healthy comparison group on two tactile perceptual tasks: (1) Graphesthesia, right affected (P < 0.003) and left unaffected (p < 0.005); and (2) Manual Form Perception (stereognosis) on the right affected (P < 0.002) and left unaffected (P < 0.002). It is possible that the somatosensory differences as measured by tactile discrimination tasks represent some degradation of the hand representation following prolonged, repetitive, near simultaneous sensory stimulation of adjacent digits. Tactile discrimination should be tested in patients with RSI to detect potential risks for developing FDh. Effective treatment of patients with RSI including FDh may need to target the somatosensory deficits in order to restore stress-free motor movements.