Use of surface electromyography to assess and select patients with idiopathic dystonia for bilateral pallidal stimulation

Fathoming the scientific paradox of intangibles: protocol reappraisal for optimizing cognitive outcomes in faciocraniosynostosis-an institutional experience

BACKGROUND

The critical nature of normal intracranial pressure (ICP) and proper airway function in early brain development, particularly in the first 5 years, are well established. These elements are compromised in faciocraniosynostoses and potentially affect neurological growth. The impact of variations in ICP and airway on cognitive development remains underappreciated and challenging to quantify.

OBJECTIVE

The primary aim of this study was to assess the efficacy and safety of a comprehensive early surgical intervention institutional protocol in children (0-5 years) with syndromic faciocraniosynostosis.

METHODS

We retrospectively analyzed our comprehensive surgical protocol in children who consecutively underwent cranial vault and midface procedures for syndromic craniosynostosis between July 2015 and January 2024, focusing on those who underwent both calvarial and midface surgeries before the age of 5 years.

SURGICAL PROTOCOL

Our treatment algorithm prioritized posterior calvarial distraction (PCVD) as the initial intervention for children with faciocraniosynostoses. Frontal orbital advancement and remodeling (FOAR) is preferred to address aesthetic concerns and ICP in older children. Midface distraction was performed for clinically significant airway compromise.

RESULTS

The cohort included 31 children with a mean age of 18.8 months at the initial surgery. The primary procedures included PCVD (n = 16), robotic-assisted frontofacial advancement (RAFFA) (n = 5), robotic-assisted midface distraction (RAMD) (n = 6), and FOAR (n = 4). The second procedure (n = 25) included RAFFA (n = 5), RAMD (n = 13), and FOAR (n = 7). The third procedure (n = 11) included RAMD (n = 1), FOAR (n = 9), and repeat PCVD (n = 1). The mean age of the patients at the final surgery was 57.5 months.

CONCLUSION

This comprehensive strategy addresses both cranial and midface issues and the challenge of optimizing cognitive development within the critical developmental window.

Pallidal and Cortical Oscillations in Freely Moving Patients With Dystonia

OBJECTIVES

To evaluate the correlation between the pallidal local field potentials (LFPs) activity and the cortical oscillations (at rest and during several motor tasks) in two freely moving patients with generalized dystonia and pallidal deep brain stimulation (DBS).

MATERIALS AND METHODS

Two women with isolated generalized dystonia were selected for bilateral globus pallidus internus (GPi) DBS. After the electrodes' implantation, cortical activity was recorded by a portable electroencephalography (EEG) system simultaneously with GPi LFPs activity, during several motor tasks, gait, and rest condition. Recordings were not performed during stimulation. EEG and LFPs signals relative to each specific movement were coupled together and grouped in neck/upper limbs movements and gait. Power spectral density (PSD), EEG-LFP coherence (through envelope of imaginary coherence operator), and 1/f exponent of LFP-PSD background were calculated.

RESULTS

In both patients, the pallidal LFPs PSD at rest was characterized by prominent 4-12 Hz activity. Voluntary movements increased activity in the theta (θ) band (4-7 Hz) compared to rest, in both LFPs and EEG signals. Gait induced a drastic raise of θ activity in both patients' pallidal activity, less marked for the EEG signal. A coherence peak within the 8-13 Hz range was found between pallidal LFPs and EEG recorded at rest.

CONCLUSIONS

Neck/upper limbs voluntary movements and gait suppressed the GPi-LFPs-cortical-EEG coherence and differently impacted both EEG and LFPs low frequency activity. These findings suggest a selective modulation of the cortico-basal ganglia network activity in dystonia.

Dystonia and Cerebellum: From Bench to Bedside

Dystonia pathogenesis remains unclear; however, findings from basic and clinical research suggest the importance of the interaction between the basal ganglia and cerebellum. After the discovery of disynaptic pathways between the two, much attention has been paid to the cerebellum. Basic research using various dystonia rodent models and clinical studies in dystonia patients continues to provide new pieces of knowledge regarding the role of the cerebellum in dystonia genesis. Herein, we review basic and clinical articles related to dystonia focusing on the cerebellum, and clarify the current understanding of the role of the cerebellum in dystonia pathogenesis. Given the recent evidence providing new hypotheses regarding dystonia pathogenesis, we discuss how the current evidence answers the unsolved clinical questions.

Skeletal Deformity in Patients With Unilateral Coronal Craniosynostosis: Perceptions of the General Public

Study Design

A two-alternative forced choice design was used to gather perceptual data regarding unicoronal synostosis (UCS).

Objective

Cranial vault remodeling aims at improving the aesthetic appearance of infants with UCS by reshaping the forehead and reducing the potential for psychosocial discrimination. People's perception of craniofacial deformity plays a role in the stigma of deformity. The purpose of this study is to examine the relationship between objective skull deformity in UCS patients and laypersons' perception of skull normality.

Methods

Forty layperson skull raters were recruited from the general public. Skull raters were asked to categorize 45 infant skull images as normal or abnormal. Twenty-one of the images were UCS skulls, and 24 were normal skulls. Skulls were displayed briefly on a computer to simulate a first impression scenario and generate a perceptual response. A χ ² analysis and mixed-effects regression model were used to analyze the response data.

Results

Members of the general public were good at distinguishing between skull groups, χ ² (1) = 281.97, P < .001. In addition, skull raters' responses were predicted by the severity of deformity in the UCS skulls (b = -0.10, z = -2.6, P = .010, CI: -0.18, -0.02). A skull with a deformity value of 2.8 mm (CI: 1.8, 4.1) was equally likely to be rated normal or abnormal.

Conclusions

This is the first study to investigate the relationship between objective skull deformity in UCS and public perception. Laypersons were good at distinguishing the difference between normal and UCS skulls, and their perceptions of normality were predicted by the degree of skull deformity.

Deep brain stimulation for myoclonus dystonia syndrome: a meta-analysis with individual patient data

Good outcomes have been reported in deep brain stimulation (DBS) for myoclonus-dystonia syndrome (M-D), a heritable disease characterized by childhood-onset myoclonic jerks and dystonia in the upper body. This meta-analysis was to evaluate the clinical outcomes consecutively, compare the stimulation targets, and identify potential prognostic factors. A systematic literature search was performed on PubMed, Web of Science, and Embase. The primary outcome was the percent improvement in Burke-Fahn-Marsden Dystonia Rating Scale movement (BFMDRS-M) scores for dystonia and Unified Myoclonus Rating Scale (UMRS) scores for myoclonus at the last follow-up visit. BFMDRS-disability scores of the patients were also summarized. Pearson correlation analyses were performed to identify the myoclonus and dystonia outcome predictors. Thirty-one studies reporting 71 patients were included. There were significant improvements in BFMDRS-M and BFMDRS-disability scores in each time category and at the last follow-up visit. Mean improvement (%) in UMRS was 79.5 ± 18.2, and 94.1% of the patients showed > 50% improvement in UMRS scores at the last follow-up visit. There was a significant trend toward improved myoclonus outcome with older age at onset and shorter disease duration. Most of the adverse events were mild and transient, and pallidal stimulation seemed to be better with respect to fewer stimulation-induced events. Based on the current data, DBS is effective for even the severe M-D. Surgery at an early stage may predict a better outcome. Although targets do not serve as the outcome predictors, pallidal stimulation may be preferred due to fewer stimulation-induced events.

Deep brain stimulation for myoclonus-dystonia syndrome with double mutations in DYT1 and DYT11

Myoclonus-dystonia syndrome (MDS) is a rare autosomal dominant inherited disorder characterized by the presentation of both myoclonic jerks and dystonia. Evidence is emerging that deep brain stimulation (DBS) may be a promising treatment for MDS. However, there are no studies reporting the effects of DBS on MDS with double mutations in DYT1 and DYT11. Two refractory MDS patients with double mutations were treated between 2011 and 2015 in our center. Genetic testing for DYT1 and DYT11 was performed through polymerase chain reaction amplification and direct sequencing of the specific exons of genes. For the first patient, initial bilateral ventral intermediate thalamus nucleus (Vim) DBS was performed. Because of worsening dystonia after initial improvement in symptoms, subsequent bilateral globus pallidus internus (GPi) DBS was offered at 43 months after initial surgery, which reversed the deterioration and restored the motor function. For the second patient, initial improvement in motor symptoms and quality of life was sustained at the follow-up 6 months after bilateral Vim DBS treatment. Thus, DBS may be an effective therapeutic option for MDS, even in patients with double mutations. Moreover, GPi DBS may be used as a supplementary treatment when initial Vim DBS fails to control MDS symptoms.

The aesthetic outcome of surgical correction for sagittal synostosis can be reliably scored by a novel method of preoperative and postoperative visual assessment

BACKGROUND

Aims of surgical correction for isolated sagittal synostosis are functional and aesthetic. Multiple surgical techniques exist; however, reliable assessment of aesthetic outcome is poorly documented, limiting direct comparisons. The pinched appearance of the temporal regions is particularly challenging to correct. A visual analogue scale was designed to grade skull shape in patients who had total or subtotal calvarial remodeling for isolated sagittal synostosis.

METHODS

Twenty-two assessors graded preoperative and postoperative photographs from 42 consecutive cases of sagittal synostosis under a single surgeon. Five aspects were graded (i.e., narrow elongated skull, frontal bossing, temporal pinching, occipital bullet, and overall shape) from 0 (normal) to 100 (severe). Interobserver and intraobserver agreement were analyzed by calculating within-subject standard deviation, coefficient of variation, and intraclass correlation coefficient. Linear regression analysis determined predictors of outcome.

RESULTS

Surgery improved outcome dramatically across all five aspects of skull shape, with a 72.6 to 76.4 percent decrease in severity score. Improvements in severity score were greater after total calvarial remodeling, and type of calvarial remodeling (total versus subtotal) was an independent predictor of outcome in all aspects of skull shape (p≤0.001). Temporal pinching was improved in a subset of patients who also had onlay bone grafts in this region.

CONCLUSIONS

Calvarial remodeling is a powerful technique for improving skull shape. A panel can detect gross and subtle aesthetic changes after surgical correction of sagittal synostosis using a visual analogue scale, with moderate interobserver and intraobserver agreement. This provides a tool for future outcome assessment.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Uncommon applications of deep brain stimulation in hyperkinetic movement disorders

Background

In addition to the established indications of tremor and dystonia, deep brain stimulation (DBS) has been utilized less commonly for several hyperkinetic movement disorders, including medication-refractory myoclonus, ballism, chorea, and Gilles de la Tourette (GTS) and tardive syndromes. Given the lack of adequate controlled trials, it is difficult to translate published reports into clinical use. We summarize the literature, draw conclusions regarding efficacy when possible, and highlight concerns and areas for future study.

Methods

A Pubmed search was performed for English-language articles between January 1980 and June 2014. Studies were selected if they focused primarily on DBS to treat the conditions of focus.

Results

We identified 49 cases of DBS for myoclonus-dystonia, 21 for Huntington's disease, 15 for choreacanthocytosis, 129 for GTS, and 73 for tardive syndromes. Bilateral globus pallidus interna (GPi) DBS was the most frequently utilized procedure for all conditions except GTS, in which medial thalamic DBS was more common. While the majority of cases demonstrate some improvement, there are also reports of no improvement or even worsening of symptoms in each condition. The few studies including functional or quality of life outcomes suggest benefit. A limited number of studies included blinded on/off testing. There have been two double-blind controlled trials performed in GTS and a single prospective double-blind, uncontrolled trial in tardive syndromes. Patient characteristics, surgical target, stimulation parameters, and duration of follow-up varied among studies.

Discussion

Despite these extensive limitations, the literature overall supports the efficacy of DBS in these conditions, in particular GTS and tardive syndromes. For other conditions, the preliminary evidence from small studies is promising and encourages further study.

Deep brain stimulation suppresses pallidal low frequency activity in patients with phasic dystonic movements

Deep brain stimulation of the globus pallidus internus alleviates involuntary movements in patients with dystonia. However, the mechanism is still not entirely understood. One hypothesis is that deep brain stimulation suppresses abnormally enhanced synchronized oscillatory activity within the motor cortico-basal ganglia network. Here, we explore deep brain stimulation-induced modulation of pathological low frequency (4-12 Hz) pallidal activity that has been described in local field potential recordings in patients with dystonia. Therefore, local field potentials were recorded from 16 hemispheres in 12 patients undergoing deep brain stimulation for severe dystonia using a specially designed amplifier allowing simultaneous high frequency stimulation at therapeutic parameter settings and local field potential recordings. For coherence analysis electroencephalographic activity (EEG) over motor areas and electromyographic activity (EMG) from affected neck muscles were recorded before and immediately after cessation of high frequency stimulation. High frequency stimulation led to a significant reduction of mean power in the 4-12 Hz band by 24.8 ± 7.0% in patients with predominantly phasic dystonia. A significant decrease of coherence between cortical EEG and pallidal local field potential activity in the 4-12 Hz range was revealed for the time period of 30 s after switching off high frequency stimulation. Coherence between EMG activity and pallidal activity was mainly found in patients with phasic dystonic movements where it was suppressed after high frequency stimulation. Our findings suggest that high frequency stimulation may suppress pathologically enhanced low frequency activity in patients with phasic dystonia. These dystonic features are the quickest to respond to high frequency stimulation and may thus directly relate to modulation of pathological basal ganglia activity, whereas improvement in tonic features may depend on long-term plastic changes within the motor network.

Surgical treatment of myoclonus dystonia syndrome

Myoclonus dystonia (M-D) syndrome is a heritable movement disorder characterized by myoclonic jerks and dystonia primarily of the upper extremities. M-D remains poorly responsive to pharmacological treatment. Emerging reports suggest good response to DBS of the internal globus pallidus (GPi) and ventral intermediate nucleus (VIM) of the thalamus. This study aimed to appraise the value of these two DBS targets by evaluating reports available in the literature. A systematic search of published case reports and case series was performed on Medline and Embase. Responses to DBS were evaluated. Myoclonus was assessed with the Unified Myoclonus Rating Scale (UMRS) and dystonia by the Burke-Fahn-Marsden dystonia rating scale (BFMDRS). The primary outcome of interest was the relative improvements noted with GPi, compared to VIM stimulation. A total of 17 publications yielded 40 unique cases, with mean follow-up of 27.2 months. All patients demonstrated improvements in myoclonus scores, with 93.5% showing at least a 50% improvement in UMRS. The mean improvement in myoclonus scores was 72.6%. In contrast, dystonia scores were improved in 87.9% of patients, with 72.7% reporting at least a 50% improvement in BFMDRS. The mean improvement in dystonia scores was 52.6%. Improvements in myoclonus scores were similar for both GPi (75.7%) and VIM (70.4%; P = 0.27). However, the improvements in dystonia scores were greater with GPi (60.2%), compared to VIM (33.3%; P = 0.03). Although both targets achieve similar improvements in myoclonus, GPi stimulation may be a preferred target because it may achieve greater improvements in dystonia, compared to VIM stimulation.

Inclusion and exclusion criteria for DBS in dystonia

When considering a patient with dystonia for deep brain stimulation (DBS) surgery several factors need to be considered. Level B evidence has shown that all motor features and associated pain in primary generalized and segmental dystonia are potentially responsive to globus pallidus internus (GPi) DBS. However, improvements in clinical series of ≥ 90% may reflect methods that need improvement, and larger prospective studies are needed to address these factors. Nevertheless, to date the selection criteria for DBS-specifically in terms of patient features (severity and nature of symptoms, age, time of evolution, or any other demographic or disease aspects)--have not been assessed in a systematic fashion. In general, dystonia patients are not considered for DBS unless medical therapies have been previously and extensively tested. The vast majority of reported patients have had DBS surgery when the disease was provoking important disability, with loss of independence and impaired quality of life. There does not appear to be an upper age limit or a minimum age limit, although there are no published data regarding the outcome of GPi DBS for dystonia in children younger than 7 years of age. There is currently no enough evidence to prove that subjects with primary--generalized dystonia who undergo DBS at an early age and sooner rather than later after disease onset may gain more benefit from DBS than those undergoing DBS after the development of fixed skeletal deformities. There is no enough evidence to refuse or support consideration of DBS in patients with previous ablative procedures.

Reconstruction of unicoronal plagiocephaly with a hypercorrection surgical technique

Object

Successful surgical repair of unicoronal plagiocephaly remains a challenge for craniofacial surgeons. Many of the surgical techniques directed at correcting the stigmata associated with this craniofacial deformity (for example, ipsilateral supraorbital rim elevation [vertical dystopia], ipsilateral temporal constriction, C-shaped deformity of the face, and so on) are not long lasting and often result in deficient correction and the need for secondary revision surgery. The authors posit that the cause of this relapse was intrinsic deficiencies of the current surgical techniques. The aim of this study was to determine if correction of unilateral coronal plagiocephaly with a novel hypercorrection surgical technique could prevent the relapse of the characteristics associated with unicoronal plagiocephaly.

Methods

The authors performed a retrospective analysis of 40 consecutive patients who underwent surgical repair of unicoronal plagiocephaly at their institution between 1999 and 2009. In all cases, the senior author (S.R.B.) used a hypercorrection technique for surgical reconstruction. Hypercorrection consisted of significant overcorrection of the affected ipsilateral frontal and anterior temporal areas in the sagittal and coronal planes. Demographic, perioperative, and follow-up data were collected for comparison. The postsurgical appearance of the forehead was documented clinically and photographically and then evaluated and scored by 2 independent graders using the expanded Whitaker scoring system. A relapse was defined as a recurrence of preoperative features that required secondary surgical correction.

Results

The mean age of the patients at the time of the operation was 13 months (range 8–28 months). The mean follow-up duration was 57 months (range 3 months to 9.8 years). The postsurgical hypercorrection appearance persisted on average 6–8 months but gradually dissipated and normalized. No patients exhibited a relapse of unicoronal plagiocephalic characteristics that required surgical correction. In all cases the aesthetic results were excellent. Only 3 patients required reoperation for the management of persistent calvarial bone defects (2 cases) and removal of a symptomatic granuloma (1 case).

Conclusions

Our study demonstrates that patients who undergo unicoronal plagiocephaly repair with a hypercorrection surgical technique avoid long-term relapse. Our results suggest that the surgical technique used in the correction of unilateral coronal synostosis is strongly associated with the prevention of postsurgical relapse and that the use of this novel method decreases the need for surgical revision.

Restoration of erect posture by deep brain stimulation of the globus pallidus in disabling dystonic spinal hyperextension

Dystonia is a movement disorder notoriously difficult to treat. While primary dystonia is classically considered to respond well to deep brain stimulation (DBS), treatment of secondary dystonia yields variable results. Patient selection should be done on a case-by-case basis. Clearly, there is a need to accumulate additional information with regard to prognostic factors that may aid neurosurgeons in selecting those patients in whom the disorder is most likely to respond favorably to pallidal DBS.

The authors report the case of a 29-year-old man with secondary dystonia due to perinatal hypoxia. The most prominent symptom was what we have termed ectatocormia—that is, severe, fixed truncal hyperextension and retrocollis, exacerbated by phasic, twisting movements of the trunk and head. This made it impossible for the patient to maintain a normal upright posture or to walk. The patient underwent bilateral DBS of the globus pallidus internus (GPi), and the authors observed impressive improvement in motor abilities and function. The patient's body adopted the normal upright posture and he became able to walk again, 4 months after the commencement of GPi stimulation.

This report, along with others, emphasizes that the GPi as an ideal target for alleviating axial tonic symptoms. The presence of normal MR imaging findings, a phenotypical purity of predominantly dystonic symptoms, and a younger age seem to favor a positive outcome.

A biomechanical study on the effect of premature fusion of the frontosphenoidal suture on orbit asymmetry in unilateral coronal synostosis

OBJECTIVE

The coronal ring of patients with unilateral coronal synostosis (UCS) presents premature fusion. This study aims to elucidate whether or not the dynamic behavior of the orbit in response to intracranial pressure (ICP) differs between patients in whom the premature fusion exists only in the frontoparietal suture (FPS) and those in whom the premature fusion extends to the frontosphenoidal suture (FSS).

METHODS

A total of 15 UCS patients were included in the present study. Patients in whom premature fusion was seen inside the FPS and those in whom premature fusion extended to the FSS were categorized as FP Only (4.2 +/- 1.4 m/o) and FP + FS groups (4.6 +/- 2.2 m/o), respectively. On the basis of computed tomography (CT) data, computer-aided design models were produced. Pressure of 15 mm Hg was applied to the neurocranium of each skull model to simulate ICP. Using the finite element method, the displacements presented by each model's orbits were calculated. Displacements of the two groups were compared.

RESULTS

The orbit demonstrated greater displacement in the FP Only group than in the FP + FS group, suggesting that premature closure of the FSS disturbs growth of the orbit in response to ICP.

CONCLUSION

In performing surgical treatment for UCS, the degree of fusion that the FSS presents should be evaluated carefully. In cases in which the FSS presents premature fusion, it is recommended to release the fusion at an early stage of cranial growth to improve the appearance of the orbital region.

Removing ECG noise from surface EMG signals using adaptive filtering

Surface electromyograms (EMGs) are valuable in the pathophysiological study and clinical treatment for dystonia. These recordings are critically often contaminated by cardiac artefact. Our objective of this study was to evaluate the performance of an adaptive noise cancellation filter in removing electrocardiogram (ECG) interference from surface EMGs recorded from the trapezius muscles of patients with cervical dystonia. Performance of the proposed recursive-least-square adaptive filter was first quantified by coherence and signal-to-noise ratio measures in simulated noisy EMG signals. The influence of parameters such as the signal-to-noise ratio, forgetting factor, filter order and regularization factor were assessed. Fast convergence of the recursive-least-square algorithm enabled the filter to track complex dystonic EMGs and effectively remove ECG noise. This adaptive filter procedure proved a reliable and efficient tool to remove ECG artefact from surface EMGs with mixed and varied patterns of transient, short and long lasting dystonic contractions.

Neck muscle synergies during stimulation and inactivation of the interstitial nucleus of Cajal (INC)

The interstitial nucleus of Cajal (INC) is thought to control torsional and vertical head posture. Unilateral microstimulation of the INC evokes torsional head rotation to positions that are maintained until stimulation offset. Unilateral INC inactivation evokes head position-holding deficits with the head tilted in the opposite direction. However, the underlying muscle synergies for these opposite behavioral effects are unknown. Here, we examined neck muscle activity in head-unrestrained monkeys before and during stimulation (50 muA, 200 ms, 300 Hz) and inactivation (injection of 0.3 mul of 0.05% muscimol) of the same INC sites. Three-dimensional eye and head movements were recorded simultaneously with electromyographic (EMG) activity in six bilateral neck muscles: sternocleidomastoid (SCM), splenius capitis (SP), rectus capitis posterior major (RCPmaj.), occipital capitis inferior (OCI), complexus (COM), and biventer cervicis (BC). INC stimulation evoked a phasic, short-latency ( approximately 5-10 ms) facilitation and later ( approximately 100-200 ms) a more tonic facilitation in the activity of ipsi-SCM, ipsi-SP, ipsi-COM, ipsi-BC, contra-RCPmaj., and contra-OCI. Unilateral INC inactivation led to an increase in the activity of contra-SCM, ipsi-SP, ipsi-RCPmaj., and ipsi-OCI and a decrease in the activity of contra-RCPmaj. and contra-OCI. Thus the influence of INC stimulation and inactivation were opposite on some muscles (i.e., contra-OCI and contra-RCPmaj.), but the comparative influences on other neck muscles were more variable. These results show that the relationship between the neck muscle responses during INC stimulation and inactivation is much more complex than the relationship between the overt behaviors.

Outcome predictors of pallidal stimulation in patients with primary dystonia: the role of disease duration

Pallidal deep brain stimulation (DBS) is currently the most effective treatment for advanced, medically refractory dystonia. However, factors predicting clinical outcome are not well defined. We reviewed the clinical records of 39 consecutive patients with medically refractory primary dystonia who underwent pallidal DBS implants. Thirty-five patients were implanted bilaterally and four unilaterally. Seven patients had fixed skeletal deformities (FSD). The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) scores at baseline, 3 and 12 months after DBS were used to evaluate clinical outcome. We investigated the outcome predictive role of several demographic and clinical factors. FSD patients had a significantly inferior outcome at 12 months, mostly affected by axial scores. All other patients (n = 32) showed a remarkable improvement (median BFMDRS percentage improvement = 87.8). Only disease duration showed a significant correlation with DBS outcome at 3 and 12 months. No other demographic and baseline clinical features predicted DBS outcome. This study confirms that patients with primary, medically refractory dystonia are generally outstanding candidates for pallidal DBS, with the possible exception of axial FSD. Patients with shorter duration of disease may expect a better general outcome. No particular predictive value should be assigned to age at onset, age at surgery, severity of disease, DYT1 status and the presence of phasic or tonic involuntary movements.

The sensory and motor representation of synchronized oscillations in the globus pallidus in patients with primary dystonia

In 15 patients with primary dystonia (six cervical and nine generalized dystonias) who were treated with bilateral chronic pallidal stimulation, we investigated the sensorimotor modulation of the oscillatory local field potentials (LFPs) recorded from the pallidal electrodes. We correlated these with the surface electromyograms in the affected muscles. The effects of involuntary, passive and voluntary movement and muscle-tendon vibration on frequency ranges of 0-3 Hz, theta (3-8 Hz), alpha (8-12 Hz), low (12-20 Hz) and high beta (20-30 Hz), and low (30-60 Hz) and high gamma (60-90 Hz) power were recorded and compared between cervical and generalized dystonia groups. Significant decreases in LFP synchronization at 8-20 Hz occurred during the sensory modulation produced by voluntary or passive movement or vibration. Voluntary movement also caused increased gamma band activity (30-90 Hz). Dystonic involuntary muscle spasms were specifically associated with increased theta, alpha and low beta (3-18 Hz). Furthermore, the increase in the frequency range of 3-20 Hz correlated with the strength of the muscle spasms and preceded them by approximately 320 ms. Differences in modulation of pallidal oscillation between cervical and generalized dystonias were also revealed. This study yields new insights into the pathophysiological mechanisms of primary dystonias and their treatment using pallidal deep brain stimulation.

Deep brain stimulation in the globus pallidus to treat dystonia: electrophysiological characteristics and 2 years' follow-up in 10 patients

Deep brain stimulation (DBS) was applied in the internal segment of the globus pallidus (GPi) to treat dystonia in 10 patients. One year after surgery the Burke-Fahn-Marsden movement scores were significantly lower than preoperative values (P=0.01). Two years after surgery the mean decrease reached 65% (P=0.001) with no motor symptoms worsening. Single unity activity was recorded in the operating room: GPi cells discharged with tonic (n=19; 29%), irregular (n=32; 48%), or burst-like activity (n=15; 23%) and fired with a mean discharge rate of 39 Hz+/-22. Some neurons demonstrated an oscillatory activity with periods lasting several seconds. Pairs of pallidal cells (n=8) recorded simultaneously displayed discharge synchronization. Movement modulated 64.4% of the cells tested, with increases in firing in 89% of cells and decreases in firing in 10% of cells. GPi cells responded to flexion and extension movements and to several passive manipulations indicating an important sensory role in dystonia. GPi neurons fired in advance of the electromyography (EMG) when the surface EMG was recorded simultaneously with the neuronal activity. Spectral analysis of the co-contracting muscles during dystonia demonstrated prominent high peaks at a low frequency band (20 Hz) during involuntary and voluntary movements. The high amplitude EMG profile recorded at rest diminished to very low values with GPi stimulation, allowing an ease of voluntary contractions. We conclude that DBS in the GPi is a reliable surgical technique for dystonia. GPi cells discharge with distinct electrophysiological characteristics that may explain some of the symptoms in dystonia. EMG recording in the operating room helps to determine which DBS contacts produce the best benefit.

3D visualization and simulation of frontoorbital advancement in metopic synostosis

OBJECTIVES

Current multislice computed tomography (CT) technology can be used for diagnosis and surgical planning applying computer-assisted three-dimensional (3D) visualization and surgical simulation. The usefulness of a technique for surgical simulation of frontoorbital advancement is demonstrated here in a child with metopic synostosis.

MATERIALS AND METHODS

Postprocessing of multi-slice CT data was performed using the software 3D slicer. 3D models were created for the purpose of surgical simulation. These allow planning the course of the osteotomies and individually placing the different bony fragments by an assigned matrix to simulate the surgical result. Photo documentation was obtained before and after surgery. Surgical simulation of the procedure allowed determination of the osteotomy course and assessment of the positioning of the individual bony fragments.

CONCLUSIONS

Computer-assisted postprocessing and simulation is a useful tool for surgical planning in craniosynostosis surgery. The time-effort for segmentation currently limits the routine clinical use of this technique.

Pallidal deep brain stimulation in patients with cranial-cervical dystonia (Meige syndrome)

Idiopathic cranial-cervical dystonia (ICCD) is an adult-onset dystonia syndrome affecting orbicularis oculi, facial, oromandibular, and cervical musculature. ICCD is frequently difficult to treat medically. Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is a highly effective treatment for idiopathic generalized dystonia, however less is known about the effect of GPi DBS on ICCD. In this article, we present the results from a pilot study assessing the effect of GPi DBS in a series of patients with ICCD. Six patients underwent bilateral stereotactic implantation of DBS leads into the sensorimotor GPi. Patients were evaluated with the Burke-Fahn-Marsden dystonia rating scale (BFMDRS) and Toronto western spamodic torticollis rating scale (TWSTRS) before surgery and 6 months postoperatively. At 6 months, patients showed a 72% mean improvement in the BFMDRS total movement score (P < 0.028, Wilcoxin signed rank test). The mean BFMDRS disability score showed a trend toward improvement (P < 0.06). The total TWSTRS score improved 54% (P < 0.043). Despite improvement in dystonia, mild worsening of motor function was reported in previously nondystonic body regions with stimulation in 4 patients. Although GPi DBS was effective in these patients, the influence of GPi DBS on nondystonic body regions deserves further investigation.

Deep brain stimulation in childhood: an effective treatment for early onset idiopathic generalised dystonia

BACKGROUND

Early onset idiopathic generalised dystonia is a progressive and profoundly disabling condition. Medical treatment may ameliorate symptoms. However, many children have profound, intractable disability including the loss of ambulation and speech, and difficulties with feeding. Following the failure of medical management, deep brain stimulation (DBS) of the globus pallidus internus (GPi) has emerged as an alternative treatment for the disorder.

METHODS

We describe four children who presented with dystonia.

RESULTS

Following the failure of a range of medical therapies, DBS systems were implanted in the GPi in an attempt to ameliorate the children's disabilities. All children found dystonic movements to be less disabling following surgery. Compared with preoperative Burke, Fahn and Marsden Dystonia Rating Scale scores, postoperative scores at 6 months were improved.

CONCLUSIONS

DBS is effective in improving symptoms and function in children with idiopathic dystonia refractory to medical treatment. Whilst surgery is complex and can be associated with intraoperative and postoperative complications, this intervention should be considered following the failure of medical therapy.