Evaluation of new instruments for screening and diagnosis of tics and tic disorders in a well-characterized sample of youth with tics and recruited controls.

Tics and tic disorders can significantly impact children, but limited screening tools and diagnostic challenges may delay access to care. The current study attempted to address these gaps by evaluating sensitivity and specificity of the Motor or Vocal Inventory of Tics (MOVeIT), a tic symptom screener, and the Description of Tic Symptoms (DoTS), a brief diagnostic assessment for tic disorders. Children (n=100, age 6-17 years old) with tic disorders attending a Tourette specialty clinic and a community-recruited sample without tics completed a gold-standard assessment by a tic expert; these evaluations were compared to child self-report and parent and teacher report versions of the MOVeIT, and child and parent versions of the DoTS. The parent and child MOVeIT met or exceeded pre-specified 85% sensitivity and specificity criteria for detecting the presence of tics when compared to a gold-standard tic expert diagnosis. The Teacher MOVeIT had lower sensitivity (71.4%) but good specificity (95.7%) for identifying any tic symptoms compared to gold standard. For determination of the presence or absence of any tic disorder, sensitivity of both parent and child DoTS was 100%; specificity of the parent DoTS was 92.7% and child DoTS specificity was 75.9%. More work may be needed to refine the teacher MOVeIT, but it is also recognized that tic expression may vary by setting. While the MOVeIT and DoTS parent and child questionnaires demonstrated adequate sensitivity and specificity for determining the presence of tics and tic disorders in this well-defined sample, additional testing in a general population is warranted.

Design of a Multisite Study Assessing the Impact of Tic Disorders on Individuals, Families, and Communities.

BACKGROUND: Tic disorders, including Tourette syndrome, are complex, multisymptom diseases, yet the impact of these disorders on affected children, families, and communities is not well understood. METHODS: To improve the understanding of the impacts of Tourette syndrome, two research groups conducted independent cross-sectional studies using qualitative and quantitative measures. They focused on similar themes, but distinct scientific objectives, and the sites collaborated to align methods of independent research proposals with the aim of increasing the analyzable sample size. RESULTS: Site 1 (University of Rochester) was a Pediatric Neurology referral center. Site 2 (University of South Florida) was a Child Psychiatry referral center. A total of 205 children with tic disorders were enrolled from both studies. The University of Rochester also enrolled 100 control children in order to clearly isolate impacts of Tourette syndrome distinct from those occurring in the general population. The majority of children with tic disorders (n = 191, 93.1%) had Tourette syndrome, the primary population targeted for these studies. Children with Tourette syndrome were similar across sites in terms of tic severity and the occurrence of comorbid conditions. The occurrence of psychiatric comorbidities in the control group was comparable with that in the general pediatric population of the United States, making this a well-justified comparison group. CONCLUSIONS: Through collaboration, two sites conducting independent research developed convergent research methods to enable pooling of data, and by extension increased power, for future analyses. This method of collaboration is a novel model for future epidemiological research of tic disorders.

Quantitative telemedicine ratings in Batten disease: implications for rare disease research.

OBJECTIVE: To determine if remote administration of the Unified Batten Disease Rating Scale (UBDRS) Physical Impairment subscale by telemedicine is reliable and feasible across a broad range of disease severity. METHODS: For the majority (n = 10) of subjects, the examination was performed by a nonphysician who had been trained to perform the examination but not to score the subjects. A trained rater scored the subjects via live video; a second trained rater performed a separate examination in person and scored that examination. For 3 telemedicine evaluations, examinations were performed and scored by a trained rater while a second trained rater simultaneously scored the subjects via live video. Reliability was determined by intraclass correlation coefficient (ICC). RESULTS: Subjects (n = 13) represented a wide range of disease severity. Remote administration of the UBDRS Physical Impairment subscale had high interrater reliability across all subjects (ICC = 0.94). When only the subjects (n = 10) who had been examined by the nonphysician and scored remotely were included in the analysis, the reliability was unchanged (ICC = 0.95). CONCLUSIONS: The UBDRS Physical Impairment subscale is reliable and feasible for remote administration. Telemedicine has the potential to be a useful tool in rare neurologic disease research and clinical assessment.

Quantifying physical decline in juvenile neuronal ceroid lipofuscinosis (Batten disease).

OBJECTIVE: To use the Unified Batten Disease Rating Scale (UBDRS) to measure the rate of decline in physical and functional capability domains in patients with juvenile neuronal ceroid lipofuscinosis (JNCL) or Batten disease, a neurodegenerative lysosomal storage disorder. We have evaluated the UBDRS in subjects with JNCL since 2002; during that time, the scale has been refined to improve reliability and validity. Now that therapies are being proposed to prevent, slow, or reverse the course of JNCL, the UBDRS will play an important role in quantitatively assessing clinical outcomes in research trials. METHODS: We administered the UBDRS to 82 subjects with JNCL genetically confirmed by CLN3 mutational analysis. Forty-four subjects were seen for more than one annual visit. From these data, the rate of physical impairment over time was quantified using multivariate linear regression and repeated-measures analysis. RESULTS: The UBDRS Physical Impairment subscale shows worsening over time that proceeds at a quantifiable linear rate in the years following initial onset of clinical symptoms. This deterioration correlates with functional capability and is not influenced by CLN3 genotype. CONCLUSION: The UBDRS is a reliable and valid instrument that measures clinical progression in JNCL. Our data support the use of the UBDRS to quantify the rate of progression of physical impairment in subjects with JNCL in clinical trials.

Research challenges in central nervous system manifestations of inborn errors of metabolism.

The Research Challenges in CNS Manifestations of Inborn Errors of Metabolism workshop was designed to address challenges in translating potential therapies for these rare disorders, and to highlight novel therapeutic strategies and innovative approaches to CNS delivery, assessment of effects and directions for the future in the treatment of these diseases. Therapies for the brain in inborn errors represent some of the greatest challenges to translational research due to the special properties of the brain, and of inborn errors themselves. This review covers the proceedings of this workshop as submitted by participants. Scientific, ethical and regulatory issues are discussed, along with ways to measure outcomes and the conduct of clinical trials. Participants included regulatory and funding agencies, clinicians, scientists, industry and advocacy groups.

Measurement of upper limb kinematics and joint angle patterns during deep brain stimulation for parkinson's disease.

Therapeutic benefits of subthalamic nucleus (STN) deep brain stimulation (DBS) for motor symptoms of Parkinson's disease (PD) are well-documented. However, the mechanisms underlying motor improvement with DBS remain poorly understood. We tested the hypothesis that STN-DBS-related improvements in voluntary arm movement kinematics are mediated by changes in the velocity and temporal sequencing of proximal joint angles. We evaluated a 56 year old male and 66 year old female with idiopathic Parkinson's disease chronically implanted with bilateral STN-DBS. Patients performed a button press task while off medication in the DBS-on and DBS-off conditions. Movements of the upper limb were recorded using a 3D motion analysis system, and detailed kinematic measures were obtained for the arm and forearm. As expected, reaction and movement times were improved in the DBS-on compared to DBS-off condition. The two subjects differed with regards to the magnitude of their changes in peak linear velocity and peak angular velocities (shoulder flexion extension, shoulder abduction adduction and elbow flexion extension). Surprisingly, both PD patients increased the frequency with which they used a preferred sequence of shoulder and elbow joint activations when in the DBS-on condition. This preferred pattern was adopted with twice the frequency than in the DBS-off condition, and with increased frequency relative to a control group of 9 age-matched controls. These results suggest that STN-DBS may improve movement execution at the cost of flexibility in movement execution strategy.

Subthalamic nucleus stimulation-induced regional blood flow responses correlate with improvement of motor signs in Parkinson disease.

Deep brain stimulation of the subthalamic nucleus (STN DBS) improves motor symptoms in idiopathic Parkinson's disease, yet the mechanism of action remains unclear. Previous studies indicate that STN DBS increases regional cerebral blood flow (rCBF) in immediate downstream targets but does not reveal which brain regions may have functional changes associated with improved motor manifestations. We studied 48 patients with STN DBS who withheld medication overnight and underwent PET scans to measure rCBF responses to bilateral STN DBS. PET scans were performed with bilateral DBS OFF and ON in a counterbalanced order followed by clinical ratings of motor manifestations using Unified Parkinson Disease Rating Scale 3 (UPDRS 3). We investigated whether improvement in UPDRS 3 scores in rigidity, bradykinesia, postural stability and gait correlate with rCBF responses in a priori determined regions. These regions were selected based on a previous study showing significant STN DBS-induced rCBF change in the thalamus, midbrain and supplementary motor area (SMA). We also chose the pedunculopontine nucleus region (PPN) due to mounting evidence of its involvement in locomotion. In the current study, bilateral STN DBS improved rigidity (62%), bradykinesia (44%), gait (49%) and postural stability (56%) (paired t-tests: P < 0.001). As expected, bilateral STN DBS also increased rCBF in the bilateral thalami, right midbrain, and decreased rCBF in the right premotor cortex (P < 0.05, corrected). There were significant correlations between improvement of rigidity and decreased rCBF in the SMA (r(s) = -0.4, P < 0.02) and between improvement in bradykinesia and increased rCBF in the thalamus (r(s) = 0.31, P < 0.05). In addition, improved postural reflexes correlated with decreased rCBF in the PPN (r(s) = -0.38, P < 0.03). These modest correlations between selective motor manifestations and rCBF in specific regions suggest possible regional selectivity for improvement of different motor signs of Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced acute transient dystonia in monkeys associated with low striatal dopamine.

Unilateral intracarotid infusion of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in baboons produces transient contralateral dystonia lasting 2-3 weeks followed by chronic hemiparkinsonism. We now extend this model to Macaca nemestrina and Macaca fascicularis. MPTP was infused unilaterally into the internal carotid artery of two M. nemestrina and 11 M. fascicularis. Effects were assessed with blinded clinical ratings of dystonia and Parkinsonism; [18F]-6-fluoro-DOPA (FDOPA) positron emission tomography; and postmortem measurements of striatal dopamine content. In two M. nemestrina, MPTP 0.4 mg/kg intracarotid produced acute dystonia within 24 h then chronic Parkinsonism starting 3 weeks later. In three M. fascicularis, MPTP 0.4 mg/kg produced acute dystonia within 3-8 h but two others died from large hemispheric infarcts within 1 day. A much lower dose, MPTP 0.1 mg/kg produced no clinical manifestations (n=1), whereas MPTP 0.25 mg/kg produced consistent transient dystonia and ipsiversive turning within 1-3 days followed by chronic Parkinsonism at 3 weeks (n=5). One week after MPTP, striatal FDOPA uptake decreased an average of 69% in M. nemestrina (0.4 mg/kg); and decreased an average of 70+/-21% in M. fascicularis (0.25 mg/kg). Striatal dopamine was reduced an average 66% in the first day (n=2) during acute dystonia, 98% at 3 days (n=1) and 99%+/-2.3% at 2-4 months (n=5). M. nemestrina had a clinical response similar to baboons whereas M. fascicularis seemed more sensitive to MPTP. These findings extend the model of MPTP-induced transient dystonia followed by chronic hemiparkinsonism to M. nemestrina and M. fascicularis and demonstrate that the early dystonic phase is accompanied by striatal dopamine deficiency.

A clinical rating scale for Batten disease: reliable and relevant for clinical trials.

BACKGROUND: Batten disease (juvenile neuronal ceroid lipofuscinosis [JNCL]) is an autosomal recessive neurodegenerative disorder characterized by blindness, seizures, and relentless decline in cognitive, motor, and behavioral function. Onset is in the early school years, with progression to death typically by late adolescence. Development of a clinical instrument to quantify severity of illness is a prerequisite to eventual assessment of experimental therapeutic interventions. OBJECTIVE: To develop a clinical rating instrument to assess motor, behavioral, and functional capability in JNCL. METHODS: A clinical rating instrument, the Unified Batten Disease Rating Scale (UBDRS), was developed by the authors to assess motor, behavioral, and functional capability in JNCL. Children with verified JNCL were evaluated independently by three neurologists. Intraclass correlation coefficients (ICCs) were used to estimate the interrater reliability for total scores in each domain. Interrater reliability for scale items was assessed with weighted kappa statistics. RESULTS: Thirty-one children with confirmed JNCL (10 boys, 21 girls) were evaluated. The mean age at symptom onset was 6.1 +/- 1.6 years, and the mean duration of illness was 9.0 +/- 4.4 years. The ICCs for the domains were as follows: motor = 0.83, behavioral = 0.68, and functional capability = 0.85. CONCLUSIONS: The Unified Batten Disease Rating Scale (UBDRS) is a reliable instrument that effectively tests for neurologic function in blind and demented patients. In its current form, the UBDRS is useful for monitoring the diverse clinical findings seen in Batten disease.

Cortical and subcortical blood flow effects of subthalamic nucleus stimulation in PD.

OBJECTIVE: To assess whether subthalamic nuclei (STN) stimulation's primary mechanism of action is to drive or inhibit output neurons. METHODS: Cerebral blood flow responses to STN stimulation were measured using PET in 13 patients with Parkinson disease. Patients were scanned with stimulators off and on (six scans each condition). Clinical ratings, EMG, and videotaping of movements were obtained at each scan. Scans with observable tremor or movement were eliminated from analysis. Brain regions where STN stimulation significantly altered blood flow were identified. RESULTS: STN stimulation increased blood flow in midbrain (including STN), globus pallidus, and thalamus, primarily on the left side, but reduced blood flow bilaterally in frontal, parietal, and temporal cortex. CONCLUSIONS: These data suggest that STN stimulation increases firing of STN output neurons, which increases inhibition of thalamocortical projections, ultimately decreasing blood flow in cortical targets. STN stimulation appears to drive, rather than inhibit, STN output neurons.

Blood flow responses to deep brain stimulation of thalamus.

BACKGROUND AND OBJECTIVE: Deep brain stimulation (DBS) of the ventral intermediate nucleus of the thalamus (VIM) provides remarkable relief of tremor in the limbs contralateral to the side of the brain stimulated. The benefits have been sufficiently dramatic that this is now an accepted clinical treatment of essential as well as other forms of tremor. Despite this clinical benefit, the mechanism of action of DBS remains unknown. In this investigation, we sought to determine the effects of VIM DBS on neuronal function. METHODS: The authors used PET measurements of qualitative regional cerebral blood flow in patients with essential tremor to determine the effects of DBS in the left VIM. Each subject had four to six scans with the arms at rest and DBS turned either on or off during alternate scans. Continuous physiologic monitoring revealed no tremor during any of the scans. The PET images from each subject were aligned, averaged, and coregistered to a standard image oriented in stereotactic space. RESULTS: The authors used subtraction image analysis with statistical parametric mapping methods and a restricted volume search to identify a significantly increased flow response at the site of stimulation in thalamus. An exploratory analysis revealed increased flow in ipsilateral supplementary motor area, a region that receives afferents from VIM. CONCLUSIONS: The increased blood flow at terminal fields of thalamocortical projections suggests that DBS stimulates and does not inactivate projection neurons in VIM thalamus.

Thalamic stimulation reduces essential tremor but not the delayed antagonist muscle timing.

BACKGROUND: Electrical stimulation of the thalamus dramatically reduces essential tremor (ET). It has been hypothesized that the cerebellum and inferior olive are involved in the generation of ET, and thalamic stimulation is presumed to dampen ET through interactions with cerebellar output to the thalamus. Evidence suggests that abnormal timing of agonist and antagonist muscle responses contribute to cerebellar tremor (CbT); however, this relationship has not been investigated for ET. The mechanisms of the tremor and improvement are unknown. OBJECTIVE: To measure the effect of ventral intermediate thalamic stimulation in controlling the ET response to sudden stretch of an agonist muscle and to determine whether, in ET, the timing relationships between the initial agonist and antagonist electromyography (EMG) responses show abnormalities similar to those seen in CbT. METHODS: The authors studied ET subjects (with implanted thalamic stimulators turned off and on) and normal controls as they responded to mechanical torque pulses given at the wrist joint. The wrist joint angle, wrist agonist, and antagonist EMG were recorded. RESULTS: Like CbT, patients with ET showed delayed onsets of antagonist EMG and excessive rebound. Thalamic stimulation reduced the tremor but did not alter the antagonist delay or the rebound. CONCLUSIONS: In ET, antagonist muscle responses to a torque pulse are similar to that in CbT. However, benefit from thalamic stimulation did not alter these EMG responses; therefore, suppression of tremor must be caused by mechanisms other than the re-establishment of normal agonist-antagonist timing.

Basal ganglia dysfunction in Tourette's syndrome: a new hypothesis.

Tourette's syndrome is a neuropsychiatric syndrome with onset in childhood that is characterized by chronic multiple tics. The cause of Tourette's syndrome is unknown, but the pathophysiology most likely involves basal ganglia and frontocortical circuits. A useful scheme of basal ganglia dysfunction should be able to account for the features that make Tourette's syndrome unique, in addition to the features that Tourette's syndrome shares with other disorders. Recent advances in knowledge of basal ganglia functional anatomy and physiology make it possible to hypothesize how specific neural mechanisms relate to specific clinical manifestations of Tourette's syndrome. A model of selection and suppression of competing behaviors by the basal ganglia is presented. The functional anatomy of basal ganglia circuits and new information on dopamine modulation of those circuits provide the basis for hypotheses of basal ganglia dysfunction in Tourette's syndrome.

Basal ganglia motor function in relation to Hallervorden-Spatz syndrome.

Hallervorden-Spatz syndrome (HSS) is a degenerative neurologic disorder associated with progressive rigidity, dystonia, impaired voluntary movement, dysarthria, and mental deterioration. Pathologically, there is iron deposition in the basal ganglia, with destruction of basal ganglia output neurons. Recent advances in the understanding of basal ganglia functional anatomy and physiology make it possible to hypothesize how specific neural mechanisms relate to specific clinical manifestations of HSS. Experimental lesions of the basal ganglia output nucleic cause involuntary muscle contractions, similar to contractions observed in dystonia. A model of selection and suppression of competing motor patterns by the basal ganglia is presented in relation to the manifestations of damage to basal ganglia output neurons. It is hypothesized that the dystonia and other motor abnormalities seen in HSS can be attributed to degeneration of basal ganglia output neurons.

Thalamic stimulation for primary writing tremor.

We report a patient with primary writing tremor whose tremor was treated with thalamic stimulation. He had undergone trials of multiple oral medications with no benefit for his tremor. An electrode lead was implanted in the thalamic nucleus ventralis intermedius with nearly complete control of his tremor and no postoperative complications. We conclude that nucleus ventralis intermedius thalamic stimulation is safe and effective for primary writing tremor.

Welding-related parkinsonism: clinical features, treatment, and pathophysiology.

OBJECTIVE: To determine whether welding-related parkinsonism differs from idiopathic PD. BACKGROUND: Welding is considered a cause of parkinsonism, but little information is available about the clinical features exhibited by patients or whether this is a distinct disorder. METHODS: The authors performed a case-control study that compared the clinical features of 15 career welders, who were ascertained through an academic movement disorders center and compared to two control groups with idiopathic PD. One control group was ascertained sequentially to compare the frequency of clinical features, and the second control group was sex- and age-matched to compare the frequency of motor fluctuations. RESULTS: Welders were exposed to a mean of 47,144 welding hours. Welders had a younger age at onset (46 years) of PD compared with sequentially ascertained controls (63 years; p < 0.0001). There was no difference in frequency of tremor, bradykinesia, rigidity, asymmetric onset, postural instability, family history, clinical depression, dementia, or drug-induced psychosis between the welders and the two control groups. All treated welders responded to levodopa. Motor fluctuations and dyskinesias occurred at a similar frequency in welders and the two control groups. PET with 6-[18F]fluorodopa obtained in two of the welders showed findings typical of idiopathic PD, with greatest loss in posterior putamen. CONCLUSIONS: Parkinsonism in welders is distinguished clinically only by age at onset, suggesting welding may be a risk factor for PD. These preliminary data cannot exclude a genetic contribution to susceptibility in these exposed individuals.

Response to levodopa challenge in Tourette syndrome.

A dopaminergic excess has been commonly postulated in the pathophysiology of tics, and an early report described acute worsening of tics with levodopa. However, dopamine agonists sometimes improve tics. We undertook this pilot study to determine whether people with tics could tolerate an acute dose of levodopa. Six adults with Tourette syndrome (TS) who had never been treated with neuroleptics took 150 mg levodopa by mouth under single-blind conditions after carbidopa pretreatment. All six subjects reported a decrease in self-rated tic severity (mean -40%, p <0.05), and three spontaneously asked if they could be prescribed levodopa for chronic treatment. Blinded videotape ratings of motor tic severity improved by 37% (p <0.02). A large, placebo-controlled trial will be required to confirm these findings, which raise important questions concerning the relationship of tic expression to dopaminergic activity.

Motor benefit from levodopa in spastic quadriplegic cerebral palsy.

We report on a 16-year-old girl with spastic quadriplegic cerebral palsy associated with premature birth and typical periventricular leukomalacia, who had a dramatic improvement in motor function after treatment with carbidopa/levodopa. Kinematic and electromyographic analyses of reaching movements demonstrate that levodopa decreased muscle co-contraction, decreased unwanted movements, and improved her ability to maintain a steady arm posture. These findings suggest that levodopa be considered as an adjunct therapy for the treatment of spastic quadriplegic cerebral palsy.

Ipsilateral thalamic stimulation after thalamotomy for essential tremor. A case report.

We report a patient with severe essential tremor who was treated with thalamic stimulation ipsilateral to a prior thalamotomy. Thalamotomy performed 30 years prior to stimulator implantation provided tremor reduction for one year before the tremor recurred. An electrode lead was implanted in the thalmaic nucleus ventralis intermedius (Vim) with nearly complete control of his tremor with sustained benefit over an 18-month follow-up period. Vim thalamic stimulation is an effective treatment option for recurrent tremor in patients who have undergone ipsilateral thalamotomy.