In humans, insulo-striate structural connectivity is largely biased toward either striosome-like or matrix-like striatal compartments

The insula is an integral component of sensory, motor, limbic, and executive functions, and insular dysfunction is associated with numerous human neuropsychiatric disorders. Insular afferents project widely, but insulo-striate projections are especially numerous. The targets of these insulo-striate projections are organized into tissue compartments, the striosome and matrix. These striatal compartments have distinct embryologic origins, afferent and efferent connectivity, dopamine pharmacology, and susceptibility to injury. Striosome and matrix appear to occupy separate sets of cortico-striato-thalamo-cortical loops, so a bias in insulo-striate projections towards one compartment may also embed an insular subregion in distinct regulatory and functional networks. Compartment-specific mapping of insulo-striate structural connectivity is sparse; the insular subregions are largely unmapped for compartment-specific projections. In 100 healthy adults, we utilized probabilistic diffusion tractography to map and quantify structural connectivity between 19 structurally-defined insular subregions and each striatal compartment. Insulo-striate streamlines that reached striosome-like and matrix-like voxels were concentrated in distinct insular zones (striosome: rostro- and caudoventral; matrix: caudodorsal) and followed different paths to reach the striatum. Though tractography was generated independently in each hemisphere, the spatial distribution and relative bias of striosome-like and matrix-like streamlines were highly similar in the left and right insula. 16 insular subregions were significantly biased towards one compartment: seven toward striosome-like voxels and nine toward matrix-like voxels. Striosome-favoring bundles had significantly higher streamline density, especially from rostroventral insular subregions. The biases in insulo-striate structural connectivity we identified mirrored the compartment-specific biases identified in prior studies that utilized injected tract tracers, cytoarchitecture, or functional MRI. Segregating insulo-striate structural connectivity through either striosome or matrix may be an anatomic substrate for functional specialization among the insular subregions.

Emerging Subspecialties: Pediatric Movement Disorders Neurology

Pediatric movement disorders (PMD) neurologists care for infants, children, and adolescents with conditions that disrupt typical movement; serving as important subspecialist child neurologists in both academic and private practice settings. In contrast to adult movement disorders neurologists whose "bread and butter" is hypokinetic Parkinson disease, PMD subspecialty practice is often dominated by hyperkinetic movement disorders including tics, dystonia, chorea, tremor, and myoclonus. PMD neurology practice intersects with a variety of subspecialties, including neonatology, developmental pediatrics, rehabilitation medicine, epilepsy, child & adolescent psychiatry, psychology, orthopedics, genetics & metabolism, and neurosurgery. Over the past several decades, significant advancements in the PMD field have included operationalizing definitions for distinct movement disorders, recognizing the spectrum of clinical phenotypes, expanding research on genetic and neuroimmunologic causes of movement disorders, and advancing available treatments. Subspecialty training in PMD provides trainees with advanced clinical, diagnostic, procedural, and management skills that reflect the complexities of contemporary practice. The child neurologist who is fascinated by the intricacies of child motor development, appreciates the power of observation skills coupled with a thoughtful physical examination, and is excited by the challenge of the unknown may be well-suited to a career as a PMD specialist.

Functional Neurological Disorder Among Sexual and Gender Minority People

Sexual and gender minority (SGM) people can face unique stressors and structural discrimination that result in higher rates of neuropsychiatric symptoms, such as depression, anxiety, and suicidality. Although more rigorous studies are needed, emerging data suggest a possible higher prevalence of functional neurological disorder and other brain-mind-body conditions in SGM people. Representation and iterative feedback from affected community members is critical to the process of developing affirming environments. More research is needed to explore the relevance of functional neurologic disorder in SGM people within a biopsychosocial framework.

In humans, striato-pallido-thalamic projections are largely segregated by their origin in either the striosome-like or matrix-like compartments

Cortico-striato-thalamo-cortical (CSTC) loops are fundamental organizing units in mammalian brains. CSTCs process limbic, associative, and sensorimotor information in largely separated but interacting networks. CTSC loops pass through paired striatal compartments, striosome (aka patch) and matrix, segregated pools of medium spiny projection neurons with distinct embryologic origins, cortical/subcortical structural connectivity, susceptibility to injury, and roles in behaviors and diseases. Similarly, striatal dopamine modulates activity in striosome and matrix in opposite directions. Routing CSTCs through one compartment may be an anatomical basis for regulating discrete functions. We used differential structural connectivity, identified through probabilistic diffusion tractography, to distinguish the striatal compartments (striosome-like and matrix-like voxels) in living humans. We then mapped compartment-specific projections and quantified structural connectivity between each striatal compartment, the globus pallidus interna (GPi), and 20 thalamic nuclei in 221 healthy adults. We found that striosome-originating and matrix-originating streamlines were segregated within the GPi: striosome-like connectivity was significantly more rostral, ventral, and medial. Striato-pallido-thalamic streamline bundles that were seeded from striosome-like and matrix-like voxels transited spatially distinct portions of the white matter. Matrix-like streamlines were 5.7-fold more likely to reach the GPi, replicating animal tract-tracing studies. Striosome-like connectivity dominated in six thalamic nuclei (anteroventral, central lateral, laterodorsal, lateral posterior, mediodorsal-medial, and medial geniculate). Matrix-like connectivity dominated in seven thalamic nuclei (centromedian, parafascicular, pulvinar-anterior, pulvinar-lateral, ventral lateral-anterior, ventral lateral-posterior, ventral posterolateral). Though we mapped all thalamic nuclei independently, functionally-related nuclei were matched for compartment-level bias. We validated these results with prior thalamostriate tract tracing studies in non-human primates and other species; where reliable data was available, all agreed with our measures of structural connectivity. Matrix-like connectivity was lateralized (left > right hemisphere) in 18 thalamic nuclei, independent of handedness, diffusion protocol, sex, or whether the nucleus was striosome-dominated or matrix-dominated. Compartment-specific biases in striato-pallido-thalamic structural connectivity suggest that routing CSTC loops through striosome-like or matrix-like voxels is a fundamental mechanism for organizing and regulating brain networks. Our MRI-based assessments of striato-thalamic connectivity in humans match and extend the results of prior tract tracing studies in animals. Compartment-level characterization may improve localization of human neuropathologies and improve neurosurgical targeting in the GPi and thalamus.

Expanding Knowledge of the Causes of Childhood Chorea

INHERITED AND ACQUIRED CHOREAS

Paolo Claudio M. de Gusmao, Jeff L. Waugh Seminars in Pediatric Neurology Volume 25, April 2018, Pages 42-53 Chorea is a symptom of a broad array of genetic, structural, and metabolic disorders. While chorea can result from systemic illness and damage to diverse brain structures, injury to the basal ganglia, especially the putamen or globus pallidus, appears to be a uniting features of these diverse neuropathologies. The timing of onset, rate of progression, and the associated neurological or systemic symptoms can often narrow the differential diagnosis to a few disorders. Recognizing the correct etiology for childhood chorea is critical, as numerous disorders in this category are potentially curable, or are remediable, with early treatment.

A Network Imaging Biomarker of X-Linked Dystonia-Parkinsonism

OBJECTIVE

The purpose of this study was to characterize a metabolic brain network associated with X-linked dystonia-parkinsonism (XDP).

METHODS

Thirty right-handed Filipino men with XDP (age = 44.4 ± 8.5 years) and 30 XDP-causing mutation negative healthy men from the same population (age = 37.4 ± 10.5 years) underwent [18 F]-fluorodeoxyglucose positron emission tomography. Scans were analyzed using spatial covariance mapping to identify a significant XDP-related metabolic pattern (XDPRP). Patients were rated clinically at the time of imaging according to the XDP-Movement Disorder Society of the Philippines (MDSP) scale.

RESULTS

We identified a significant XDPRP topography from 15 randomly selected subjects with XDP and 15 control subjects. This pattern was characterized by bilateral metabolic reductions in caudate/putamen, frontal operculum, and cingulate cortex, with relative increases in the bilateral somatosensory cortex and cerebellar vermis. Age-corrected expression of XDPRP was significantly elevated (p < 0.0001) in XDP compared to controls in the derivation set and in the remaining 15 patients (testing set). We validated the XDPRP topography by identifying a similar pattern in the original testing set (r = 0.90, p < 0.0001; voxel-wise correlation between both patterns). Significant correlations between XDPRP expression and clinical ratings for parkinsonism-but not dystonia-were observed in both XDP groups. Further network analysis revealed abnormalities of information transfer through the XDPRP space, with loss of normal connectivity and gain of abnormal functional connections linking network nodes with outside brain regions.

INTERPRETATION

XDP is associated with a characteristic metabolic network associated with abnormal functional connectivity among the basal ganglia, thalamus, motor regions, and cerebellum. Clinical signs may relate to faulty information transfer through the network to outside brain regions. ANN NEUROL 2023;94:684-695.

A Case Series of Transgender and Gender-Nonconforming Patients in a Pediatric Functional Neurologic Disorder Clinic

Youth who identify as transgender and gender nonconforming (TGNC) are at increased risk of anxiety, depression, bullying, and loss of social and family support. These factors may increase the risk of developing functional neurologic disorder (FND). If the risk of FND is increased in TGNC youth, then identifying which youth are at increased risk, and the particular times when risk is increased, may allow for earlier diagnosis and treatment of FND. Better awareness of functional symptoms among clinicians who care for TGNC youth may prevent disruption of gender-affirming care if FND symptoms emerge. Patients diagnosed with FND who are TGNC may require different forms of intervention than other youth with FND. We present 4 cases from our multidisciplinary pediatric FND program of TGNC youth who developed FND. In all individuals for whom follow-up information was available, access to gender-affirming health care was associated with marked improvement or resolution of FND symptoms.

Cachexia, chorea, and pain in chronic nonbacterial osteitis and inflammatory bowel disease: a case report

BACKGROUND

Inflammatory bowel disease is an inflammatory disorder that primarily impacts the gastrointestinal tract, leading to malnutrition and chronic microscopic intestinal blood loss. Uncontrolled systemic inflammation can impact other parts of the body, known as extraintestinal manifestations. Up to 25% of patients with inflammatory bowel disease are reported to have these complications in their skin, joints, bones, eyes, liver, lung, and pancreas (Rogler et al. in Gastroenterology 161(4):1118-1132, 2021). Neurologic involvement as extraintestinal manifestations are less common, reported at 3-19%, including neuropathies, demyelination, and cerebrovascular events (Morís in World J Gastroenterol. 20(5):1228-1237, 2014).

CASE PRESENTATION

A 13-year-old Caucasian boy presented with 1 month of progressive lower-extremity pain, weakness, and weight loss. His physical examination was notable for cachexia, lower-extremity weakness, and chorea. Labs revealed normocytic anemia and systemic inflammation. Imaging revealed symmetric abnormal marrow signal in the pelvis and upper femurs. Pathologic examination of the bone revealed chronic inflammation consistent with chronic nonbacterial osteitis. Endoscopy revealed colonic inflammation consistent with inflammatory bowel disease.

CONCLUSIONS

Children and adolescents with musculoskeletal pain lasting more than 2 weeks with systemic signs or symptoms like weight loss should prompt evaluation for systemic inflammatory disorders such as chronic nonbacterial osteitis, which can occur in isolation or associated with inflammatory bowel disease. This patient also had a nonspecific neurologic abnormality, chorea, which resolved with treatment of underlying inflammatory disorder. These extraintestinal manifestations may be concurrent with or precede intestinal inflammation, requiring a high index of suspicion when investigating nonspecific systemic inflammation.

An MRI method for parcellating the human striatum into matrix and striosome compartments in vivo

The mammalian striatum is comprised of intermingled tissue compartments, matrix and striosome. Though indistinguishable by routine histological techniques, matrix and striosome have distinct embryologic origins, afferent/efferent connections, surface protein expression, intra-striatal location, susceptibilities to injury, and functional roles in a range of animal behaviors. Distinguishing the compartments previously required post-mortem tissue and/or genetic manipulation; we aimed to identify matrix/striosome non-invasively in living humans. We used diffusion MRI (probabilistic tractography) to identify human striatal voxels with connectivity biased towards matrix-favoring or striosome-favoring regions (determined by prior animal tract-tracing studies). Segmented striatal compartments replicated the topological segregation and somatotopic organization identified in animal matrix/striosome studies. Of brain regions mapped in prior studies, our human brain data confirmed 93% of the compartment-selective structural connectivity demonstrated in animals. Test-retest assessment on repeat scans found a voxel classification error rate of 0.14%. Fractional anisotropy was significantly higher in matrix-like voxels, while mean diffusivity did not differ between the compartments. As mapped by the Talairach human brain atlas, 460 regions were significantly biased towards either matrix or striosome. Our method allows the study of striatal compartments in human health and disease, in vivo, for the first time.

Changing the culture of care for children and adolescents with functional neurological disorder

As members of a multidisciplinary team of professionals who treat children and adolescents with functional neurological (conversion) disorder (FND), we highlight the pressing need to develop an FND-informed culture of care that takes into account recent advances in our understanding of this group of patients. Stories of clinical encounters in health care settings from around the world-told by children and adolescents with FND, their parents, and health professionals-portray an outdated culture of care characterized by iatrogenic stigma, erosion of empathy and compassion within the clinician-patient relationship, and a lack of understanding of FND and its complex neurobiology. After a brief exploration of the outdated culture, we share our counterstories: how we and our colleagues have worked, and continue to work, to create an FND-informed culture in the health systems where we practice. We discuss the therapeutic use of child-friendly language. We also discuss a range of structural, educational, and process interventions that can be used to promote FND-informed beliefs and attitudes, FND-informed clinician-patient encounters, and FND-informed referral processes, treatment pathways, and therapeutic interventions.

When neurologists diagnose functional neurological disorder, why don't they code for it?

Objective:

Clinicians who recognize functional neurological disorders (FND) may not share that diagnosis with patients. Poor communication delays treatment and contributes to substantial disability in FND. Diagnostic (ICD-10) coding, one form of medical communication, offers an insight into clinicians’ face-to-face communication. Therefore, quantifying the phenomenon of non-coding, and identifying beliefs and practice habits that reduce coding, may suggest routes to improve medical communication in FND.

Methods:

We reviewed all pediatric neurology consultations in our hospital from 2017–2020, selecting those in which neurologists explicitly stated an FND-related diagnosis (N=57). We identified the neurological symptoms and ICD-10 codes assigned for each consultation. In parallel, we reviewed all encounters that utilized FND-related codes to determine whether insurers paid for this care. Finally, we assessed beliefs and practices that influence FND-related coding through a nationwide survey of pediatric neurologists (N=460).

Results:

After diagnosing FND, neurologists selected FND-related ICD-10 codes in only 22.8% of consultations. 96.2% of neurologists estimated that they would code for non-epileptic seizure (NES) when substantiated by EEG; in practice, they coded for 36.7% of such consultations. For other FND manifestations, neurologists coded in only 13.3% of cases. When presented with FND and non-FND scenarios with equal levels of information, neurologists coded for FND 41% less often. The strongest predictor of non-coding was the outdated belief that FND is a diagnosis of exclusion. Coding for FND never resulted in insurance non-payment.

Conclusion:

Non-coding for FND is common. Most factors that amplify non-coding also hinder face-to-face communication. Research based on ICD-10 coding (e.g., prevalence, cost) may underestimate the impact of FND by >4-fold.

KMT2B-related disorders: expansion of the phenotypic spectrum and long-term efficacy of deep brain stimulation

Heterozygous mutations in KMT2B are associated with an early-onset, progressive and often complex dystonia (DYT28). Key characteristics of typical disease include focal motor features at disease presentation, evolving through a caudocranial pattern into generalized dystonia, with prominent oromandibular, laryngeal and cervical involvement. Although KMT2B-related disease is emerging as one of the most common causes of early-onset genetic dystonia, much remains to be understood about the full spectrum of the disease. We describe a cohort of 53 patients with KMT2B mutations, with detailed delineation of their clinical phenotype and molecular genetic features. We report new disease presentations, including atypical patterns of dystonia evolution and a subgroup of patients with a non-dystonic neurodevelopmental phenotype. In addition to the previously reported systemic features, our study has identified co-morbidities, including the risk of status dystonicus, intrauterine growth retardation, and endocrinopathies. Analysis of this study cohort (n = 53) in tandem with published cases (n = 80) revealed that patients with chromosomal deletions and protein truncating variants had a significantly higher burden of systemic disease (with earlier onset of dystonia) than those with missense variants. Eighteen individuals had detailed longitudinal data available after insertion of deep brain stimulation for medically refractory dystonia. Median age at deep brain stimulation was 11.5 years (range: 4.5-37.0 years). Follow-up after deep brain stimulation ranged from 0.25 to 22 years. Significant improvement of motor function and disability (as assessed by the Burke Fahn Marsden's Dystonia Rating Scales, BFMDRS-M and BFMDRS-D) was evident at 6 months, 1 year and last follow-up (motor, P = 0.001, P = 0.004, and P = 0.012; disability, P = 0.009, P = 0.002 and P = 0.012). At 1 year post-deep brain stimulation, >50% of subjects showed BFMDRS-M and BFMDRS-D improvements of >30%. In the long-term deep brain stimulation cohort (deep brain stimulation inserted for >5 years, n = 8), improvement of >30% was maintained in 5/8 and 3/8 subjects for the BFMDRS-M and BFMDRS-D, respectively. The greatest BFMDRS-M improvements were observed for trunk (53.2%) and cervical (50.5%) dystonia, with less clinical impact on laryngeal dystonia. Improvements in gait dystonia decreased from 20.9% at 1 year to 16.2% at last assessment; no patient maintained a fully independent gait. Reduction of BFMDRS-D was maintained for swallowing (52.9%). Five patients developed mild parkinsonism following deep brain stimulation. KMT2B-related disease comprises an expanding continuum from infancy to adulthood, with early evidence of genotype-phenotype correlations. Except for laryngeal dysphonia, deep brain stimulation provides a significant improvement in quality of life and function with sustained clinical benefit depending on symptoms distribution.

Role of child neurologists and neurodevelopmentalists in the diagnosis of cerebral palsy: A survey study

OBJECTIVE

To contextualize the role of child neurologists and neurodevelopmentalists (CNs/NDDs) in cerebral palsy (CP) care, we review the changing landscape of CP diagnosis and survey stakeholder CNs/NDDs regarding their roles in CP care.

METHODS

The optimal roles of the multiple specialties involved in CP care are currently unclear, particularly regarding CP diagnosis. We developed recommendations regarding the role of CNs/NDDs noting (1) increasing complexity of CP diagnosis given a growing number of genetic etiologies and treatable motor disorders that can be misdiagnosed as CP and (2) the views of a group of physician stakeholders (CNs/NDDs from the Child Neurology Society Cerebral Palsy Special Interest Group).

RESULTS

CNs/NDDs felt that they were optimally suited to diagnose CP. Many (76%) felt that CNs/NDDs should always be involved in CP diagnosis. However, 42% said that their patients with CP were typically not diagnosed by CNs/NDDs, and 18% did not receive referrals to establish the diagnosis of CP at all. CNs/NDDs identified areas of their expertise critical for CP diagnosis including knowledge of the neurologic examination across development and early identification of features atypical for CP. This contrasts with their views on CP management, where CNs/NDDs felt that they could contribute to the medical team, but were necessary primarily when neurologic coexisting conditions were present.

DISCUSSION

Given its increasing complexity, we recommend early referral for CP diagnosis to a CN/NDD or specialist with comparable expertise. This contrasts with current consensus guidelines, which either do not address or do not recommend specific specialist referral for CP diagnosis.

Management of Infantile Spasms During the COVID-19 Pandemic

Circumstances of the COVID-19 pandemic have mandated a change to standard management of infantile spasms. On April 6, 2020, the Child Neurology Society issued an online statement of immediate recommendations to streamline diagnosis and treatment of infantile spasms with utilization of telemedicine, outpatient studies, and selection of first-line oral therapies as initial treatment. The rationale for the recommendations and specific guidance including follow-up assessment are provided in this manuscript. These recommendations are indicated as enduring if intended to outlast the pandemic, and limited if intended only for the pandemic health care crisis but may be applicable to future disruptions of health care delivery.

Missense variants in TAF1 and developmental phenotypes: challenges of determining pathogenicity

We recently described a new neurodevelopmental syndrome (TAF1/MRXS33 intellectual disability syndrome) (MIM# 300966) caused by pathogenic variants involving the X-linked gene TAF1, which participates in RNA polymerase II transcription. The initial study reported eleven families, and the syndrome was defined as presenting early in life with hypotonia, facial dysmorphia, and developmental delay that evolved into intellectual disability (ID) and/or autism spectrum disorder (ASD). We have now identified an additional 27 families through a genotype-first approach. Familial segregation analysis, clinical phenotyping, and bioinformatics were capitalized on to assess potential variant pathogenicity, and molecular modelling was performed for those variants falling within structurally characterized domains of TAF1. A novel phenotypic clustering approach was also applied, in which the phenotypes of affected individuals were classified using 51 standardized Human Phenotype Ontology (HPO) terms. Phenotypes associated with TAF1 variants show considerable pleiotropy and clinical variability, but prominent among previously unreported effects were brain morphological abnormalities, seizures, hearing loss, and heart malformations. Our allelic series broadens the phenotypic spectrum of TAF1/MRXS33 intellectual disability syndrome and the range of TAF1 molecular defects in humans. It also illustrates the challenges for determining the pathogenicity of inherited missense variants, particularly for genes mapping to chromosome X. This article is protected by copyright. All rights reserved.

Subtle Imaging Findings Aid the Diagnosis of Adolescent Hereditary Spastic Paraplegia and Ataxia

PURPOSE

Hereditary spastic paraplegia (HSP) and hereditary spastic ataxia (HSA) are a heterogeneous group of genetic disorders characterized by progressive lower limb spasticity resulting from pyramidal tract dysfunction. By identifying critical imaging findings within the clinical context of spasticity, radiologists are uniquely positioned to recommend specific genetic testing, and thus facilitate diagnosis.

METHODS

We present two examples of HSP and HSA that had gone clinically unrecognized for years, and in which magnetic resonance imaging played a critical role in the diagnosis.

RESULTS

Radiologists' awareness of HSP and HSA, combined with a critical review of the clinical history and characteristic imaging findings led to specific genetic testing and a definitive diagnosis.

CONCLUSION

Awareness of HSP and HSA among radiologists will expedite more accurate diagnosis, explanation of patient symptoms, recommendation for syndrome-specific treatment, and family planning considerations.

White Matter Changes in Cervical Dystonia Relate to Clinical Effectiveness of Botulinum Toxin Treatment

In a previous report showing white matter microstructural hemispheric asymmetries medial to the pallidum in focal dystonias, we showed preliminary evidence that this abnormality was reduced 4 weeks after botulinum toxin (BTX) injections. In the current study we report the completed treatment study in a full-size cohort of CD patients (n = 14). In addition to showing a shift toward normalization of the hemispheric asymmetry, we evaluated clinical relevance of these findings by relating white matter changes to degree of symptom improvement. We also evaluated whether the magnitude of the white matter asymmetry before treatment was related to severity, laterality, duration of dystonia, and/or number of previous BTX injections. Our results confirm the findings of our preliminary report: we observed significant fractional anisotropy (FA) changes medial to the pallidum 4 weeks after BTX in CD participants that were not observed in controls scanned at the same interval. There was a significant relationship between magnitude of hemispheric asymmetry and dystonia symptom improvement, as measured by percent reduction in dystonia scale scores. There was also a trend toward a relationship between magnitude of pre-injection white matter asymmetry and symptom severity, but not symptom laterality, disorder duration, or number of previous BTX injections. Post-hoc analyses suggested the FA changes at least partially reflected changes in pathophysiology, but a dissociation between patient perception of benefit from injections and FA changes suggested the changes did not reflect changes to the primary "driver" of the dystonia. In contrast, there were no changes or group differences in DTI diffusivity measures, suggesting the hemispheric asymmetry in CD does not reflect irreversible white matter tissue loss. These findings support the hypothesis that central nervous system white matter changes are involved in the mechanism by which BTX exerts clinical benefit.

Spectrum of neurodevelopmental disease associated with the GNAO1 guanosine triphosphate-binding region

OBJECTIVE

To characterize the phenotypic spectrum associated with GNAO1 variants and establish genotype-protein structure-phenotype relationships.

METHODS

We evaluated the phenotypes of 14 patients with GNAO1 variants, analyzed their variants for potential pathogenicity, and mapped them, along with those in the literature, on a three-dimensional structural protein model.

RESULTS

The 14 patients in our cohort, including one sibling pair, had 13 distinct, heterozygous GNAO1 variants classified as pathogenic or likely pathogenic. We attributed the same variant in two siblings to parental mosaicism. Patients initially presented with seizures beginning in the first 3 months of life (8/14), developmental delay (4/14), hypotonia (1/14), or movement disorder (1/14). All patients had hypotonia and developmental delay ranging from mild to severe. Nine had epilepsy, and nine had movement disorders, including dystonia, ataxia, chorea, and dyskinesia. The 13 GNAO1 variants in our patients are predicted to result in amino acid substitutions or deletions in the GNAO1 guanosine triphosphate (GTP)-binding region, analogous to those in previous publications. Patients with variants affecting amino acids 207-221 had only movement disorder and hypotonia. Patients with variants affecting the C-terminal region had the mildest phenotypes.

SIGNIFICANCE

GNAO1 encephalopathy most frequently presents with seizures beginning in the first 3 months of life. Concurrent movement disorders are also a prominent feature in the spectrum of GNAO1 encephalopathy. All variants affected the GTP-binding domain of GNAO1, highlighting the importance of this region for G-protein signaling and neurodevelopment.

A registration method for improving quantitative assessment in probabilistic diffusion tractography

Diffusion MRI-based probabilistic tractography is a powerful tool for non-invasively investigating normal brain architecture and alterations in structural connectivity associated with disease states. Both voxelwise and region-of-interest methods of analysis are capable of integrating population differences in tract amplitude (streamline count or density), given proper alignment of the tracts of interest. However, quantification of tract differences (between groups, or longitudinally within individuals) has been hampered by two related features of white matter. First, it is unknown to what extent healthy individuals differ in the precise location of white matter tracts, and to what extent experimental factors influence perceived tract location. Second, white matter lacks the gross neuroanatomical features (e.g., gyri, histological subtyping) that make parcellation of grey matter plausible - determining where tracts "should" lie within larger white matter structures is difficult. Accurately quantifying tractographic connectivity between individuals is thus inherently linked to the difficulty of identifying and aligning precise tract location. Tractography is often utilized to study neurological diseases in which the precise structural and connectivity abnormalities are unknown, underscoring the importance of accounting for individual differences in tract location when evaluating the strength of structural connectivity. We set out to quantify spatial variance in tracts aligned through a standard, whole-brain registration method, and to assess the impact of location mismatch on groupwise assessments of tract amplitude. We then developed a method for tract alignment that enhances the existing standard whole brain registration, and then tested whether this method improved the reliability of groupwise contrasts. Specifically, we conducted seed-based probabilistic diffusion tractography from primary motor, supplementary motor, and visual cortices, projecting through the corpus callosum. Streamline counts decreased rapidly with movement from the tract center (-35% per millimeter); tract misalignment of a few millimeters caused substantial compromise of amplitude comparisons. Alignment of tracts "peak-to-peak" is essential for accurate amplitude comparisons. However, for all transcallosal tracts registered through the whole-brain method, the mean separation distance between an individual subject's tract and the average tract (3.2 mm) precluded accurate comparison: at this separation, tract amplitudes were reduced by 74% from peak value. In contrast, alignment of subcortical tracts (thalamo-putaminal, pallido-rubral) was substantially better than alignment for cortical tracts; whole-brain registration was sufficient for these subcortical tracts. We demonstrated that location mismatches in cortical tractography were sufficient to produce false positive and false negative amplitude estimates in both groupwise and longitudinal comparisons. We then showed that our new tract alignment method substantially reduced location mismatch and improved both reliability and statistical power of subsequent quantitative comparisons.

Inherited and Acquired Choreas

Chorea is a symptom of a broad array of genetic, structural, and metabolic disorders. While chorea can result from systemic illness and damage to diverse brain structures, injury to the basal ganglia, especially the putamen or globus pallidus, appears to be a uniting features of these diverse neuropathologies. The timing of onset, rate of progression, and the associated neurological or systemic symptoms can often narrow the differential diagnosis to a few disorders. Recognizing the correct etiology for childhood chorea is critical, as numerous disorders in this category are potentially curable, or are remediable, with early treatment.

PURA syndrome: clinical delineation and genotype-phenotype study in 32 individuals with review of published literature

BACKGROUND

De novo mutations in PURA have recently been described to cause PURA syndrome, a neurodevelopmental disorder characterised by severe intellectual disability (ID), epilepsy, feeding difficulties and neonatal hypotonia.

OBJECTIVES

To delineate the clinical spectrum of PURA syndrome and study genotype-phenotype correlations.

METHODS

Diagnostic or research-based exome or Sanger sequencing was performed in individuals with ID. We systematically collected clinical and mutation data on newly ascertained PURA syndrome individuals, evaluated data of previously reported individuals and performed a computational analysis of photographs. We classified mutations based on predicted effect using 3D in silico models of crystal structures of Drosophila-derived Pur-alpha homologues. Finally, we explored genotype-phenotype correlations by analysis of both recurrent mutations as well as mutation classes.

RESULTS

We report mutations in PURA (purine-rich element binding protein A) in 32 individuals, the largest cohort described so far. Evaluation of clinical data, including 22 previously published cases, revealed that all have moderate to severe ID and neonatal-onset symptoms, including hypotonia (96%), respiratory problems (57%), feeding difficulties (77%), exaggerated startle response (44%), hypersomnolence (66%) and hypothermia (35%). Epilepsy (54%) and gastrointestinal (69%), ophthalmological (51%) and endocrine problems (42%) were observed frequently. Computational analysis of facial photographs showed subtle facial dysmorphism. No strong genotype-phenotype correlation was identified by subgrouping mutations into functional classes.

CONCLUSION

We delineate the clinical spectrum of PURA syndrome with the identification of 32 additional individuals. The identification of one individual through targeted Sanger sequencing points towards the clinical recognisability of the syndrome. Genotype-phenotype analysis showed no significant correlation between mutation classes and disease severity.

Increased insula-putamen connectivity in X-linked dystonia-parkinsonism

Preliminary evidence from postmortem studies of X-linked dystonia-parkinsonism (XDP) suggests tissue loss may occur first and/or most severely in the striatal striosome compartment, followed later by cell loss in the matrix compartment. However, little is known about how this relates to pathogenesis and pathophysiology. While MRI cannot visualize these striatal compartments directly in humans, differences in relative gradients of afferent cortical connectivity across compartments (weighted toward paralimbic versus sensorimotor cortex, respectively) can be used to infer potential selective loss in vivo. In the current study we evaluated relative connectivity of paralimbic versus sensorimotor cortex with the caudate and putamen in 17 individuals with XDP and 17 matched controls. Although caudate and putamen volumes were reduced in XDP, there were no significant reductions in either “matrix-weighted”, or “striosome-weighted” connectivity. In fact, paralimbic connectivity with the putamen was elevated, rather than reduced, in XDP. This was driven most strongly by elevated putamen connectivity with the anterior insula. There was no relationship of these findings to disease duration or striatal volume, suggesting insula and/or paralimbic connectivity in XDP may develop abnormally and/or increase in the years before symptom onset.

•

Previous work suggested striosomes might degenerate preferentially in early XDP.

•

We developed a DTI tractography method to assess striosome and matrix integrity.

•

Striosomal afferents to putamen were elevated in XDP, despite reduced putamen volume.

•

Connectivity was particularly elevated from the insula (two to three-fold).

•

Striosome connectivity strength was not associated with disease duration.

Defining Hand Stereotypies in Rett Syndrome: A Movement Disorders Perspective

INTRODUCTION

Hand stereotypies (HS) are a primary diagnostic criterion for Rett syndrome (RTT) but are difficult to characterize and quantify systematically.

METHODS

We collected video on 27 girls (2-12 years of age) with classic RTT who participated in a mecasermin trial. The present study focused exclusively on video analyses, by reviewing two five-minute windows per subject to identify the two most common HS. Three raters with expertise in movement disorders independently rated the five-minute windows using standardized terminology to determine the level of agreement. We iteratively refined the protocol in three stages to improve descriptive accuracy, categorizing HS as "central" or "peripheral," "simple" or "complex," scoring each hand separately. Inter-rater agreement was analyzed using Kappa statistics.

RESULTS

In the initial protocol evaluating HS by video, inter-rater agreement was 20.7%. In the final protocol, inter-rater agreement for the two most frequent HS was higher than the initial protocol at 50%.

CONCLUSION

Phenotypic variability makes standardized evaluation of HS in RTT a challenge; we achieved only 50% level of agreement and only for the most frequent HS. Therefore, objective measures are needed to evaluate HS.

Treatment of ADCY5-Associated Dystonia, Chorea, and Hyperkinetic Disorders With Deep Brain Stimulation: A Multicenter Case Series

ADCY5 mutations have been reported as a cause of early onset hyperkinetic movements associated with delayed motor milestones, hypotonia, and exacerbation during sleep. The movement disorder may be continuous or episodic, and can vary considerably in severity within families and in individuals. The authors report a case series of 3 patients with ADCY5 mutations treated with deep brain stimulation after unsuccessful medication trials. All had extensive imaging, metabolic, and genetic testing prior to confirmation of their ADCY5 mutation. Two of the patients had the c.1252C>T; p.R418W mutation, while the youngest and most severely affected had a de novo c.2080_2088del; p.K694_M696 mutation. All had variable and incomplete, but positive responses to deep brain stimulation. The authors conclude that deep brain stimulation may provide benefit in ADCY5-related movement disorders. Long-term efficacy remains to be confirmed by longitudinal observation. ADCY5 should be considered in the differential diagnosis of early onset hyperkinetic movement disorders, and may respond to deep brain stimulation.

Thalamic Volume Is Reduced in Cervical and Laryngeal Dystonias

BACKGROUND

Dystonia, a debilitating movement disorder characterized by abnormal fixed positions and/or twisting postures, is associated with dysfunction of motor control networks. While gross brain lesions can produce secondary dystonias, advanced neuroimaging techniques have been required to identify network abnormalities in primary dystonias. Prior neuroimaging studies have provided valuable insights into the pathophysiology of dystonia, but few directly assessed the gross volume of motor control regions, and to our knowledge, none identified abnormalities common to multiple types of idiopathic focal dystonia.

METHODS

We used two gross volumetric segmentation techniques and one voxelwise volumetric technique (voxel based morphometry, VBM) to compare regional volume between matched healthy controls and patients with idiopathic primary focal dystonia (cervical, n = 17, laryngeal, n = 7). We used (1) automated gross volume measures of eight motor control regions using the FreeSurfer analysis package; (2) blinded, anatomist-supervised manual segmentation of the whole thalamus (also gross volume); and (3) voxel based morphometry, which measures local T1-weighted signal intensity and estimates gray matter density or volume at the level of single voxels, for both whole-brain and thalamus.

RESULTS

Using both automated and manual gross volumetry, we found a significant volume decrease only in the thalamus in two focal dystonias. Decreases in whole-thalamic volume were independent of head and brain size, laterality of symptoms, and duration. VBM measures did not differ between dystonia and control groups in any motor control region.

CONCLUSIONS

Reduced thalamic gross volume, detected in two independent analyses, suggests a common anatomical abnormality in cervical dystonia and spasmodic dysphonia. Defining the structural underpinnings of dystonia may require such complementary approaches.

Localization of Basal Ganglia and Thalamic Damage in Dyskinetic Cerebral Palsy

BACKGROUND

Dyskinetic cerebral palsy affects 15%-20% of patients with cerebral palsy. Basal ganglia injury is associated with dyskinetic cerebral palsy, but the patterns of injury within the basal ganglia predisposing to dyskinetic cerebral palsy are unknown, making treatment difficult. For example, deep brain stimulation of the globus pallidus interna improves dystonia in only 40% of patients with dyskinetic cerebral palsy. Basal ganglia injury heterogeneity may explain this variability.

METHODS

To investigate this, we conducted a qualitative systematic review of basal ganglia and thalamic damage in dyskinetic cerebral palsy. Reviews and articles primarily addressing genetic or toxic causes of cerebral palsy were excluded yielding 22 studies (304 subjects).

RESULTS

Thirteen studies specified the involved basal ganglia nuclei (subthalamic nucleus, caudate, putamen, globus pallidus, or lentiform nuclei, comprised by the putamen and globus pallidus). Studies investigating the lentiform nuclei (without distinguishing between the putamen and globus pallidus) showed that all subjects (19 of 19) had lentiform nuclei damage. Studies simultaneously but independently investigating the putamen and globus pallidus also showed that all subjects (35 of 35) had lentiform nuclei damage (i.e., putamen or globus pallidus damage); this was followed in frequency by damage to the putamen alone (70 of 101, 69%), the subthalamic nucleus (17 of 25, 68%), the thalamus (88 of 142, 62%), the globus pallidus (7/35, 20%), and the caudate (6 of 47, 13%). Globus pallidus damage was almost always coincident with putaminal damage.

CONCLUSIONS

Noting consistent involvement of the lentiform nuclei in dyskinetic cerebral palsy, these results could suggest two groups of patients with dyskinetic cerebral palsy: those with putamen-predominant damage and those with panlenticular damage involving both the putamen and the globus pallidus. Differentiating between these groups could help predict response to therapies such as deep brain stimulation.

Benign hereditary chorea related to NKX2-1 with ataxia and dystonia

Benign hereditary chorea (BHC) was originally described in 1967, but it was not until 2002 that linkage analysis and positional cloning identified the causative gene, NKX2-1 (also known as TTF-1).(1,2) The range of manifestations spans from isolated chorea, pulmonary disease, or thyroid dysfunction, with one-third of patients having the full brain-lung-thyroid syndrome.(3) Recent reports have expanded the NKX2-1 phenotype, as patients may present with additional movement disorders such as dystonia and myoclonus.(3) We present a case with early-onset chorea, ataxia, and dystonia.

Increased pediatric functional neurological symptom disorders after the Boston marathon bombings: a case series

BACKGROUND

Functional neurological symptom disorders are frequently the basis for acute neurological consultation. In children, they are often precipitated by high-frequency everyday stressors. The extent to which a severe traumatic experience may also precipitate functional neurological abnormalities is unknown.

METHODS

For the 2-week period after the Boston Marathon bombings, we prospectively collected data on patients whose presentation suggested a functional neurological symptom disorder. We assessed clinical and demographic variables, duration of symptoms, extent of educational impact, and degree of connection to the Marathon bombing. We contacted all patients at 6 months after presentation to determine the outcome and accuracy of the diagnosis.

RESULTS

In a parallel study, we reported a baseline of 2.6 functional neurological presentations per week in our emergency room. In the week after the Marathon bombings, this frequency tripled. Ninety-one percent of presentations were delayed by 1 week, with onset around the first school day after a city-wide lockdown. Seventy-three percent had a history of a prior psychiatric diagnosis. At the 6 months follow-up, no functional neurological symptom disorder diagnoses were overturned and no new organic diagnosis was made.

CONCLUSIONS

Pediatric functional neurological symptom disorder may be precipitated by both casual and high-intensity stressors. The 3.4-fold increase in incidence after the Boston Marathon bombings and city-wide lockdown demonstrates the marked effect that a community-wide tragedy can have on the mental health of children. Care providers must be aware of functional neurological symptom disorders after stressful community events in vulnerable patient populations, particularly those with prior psychiatric diagnoses.

Education in medical billing benefits both neurology trainees and academic departments

The objective of residency training is to produce physicians who can function independently within their chosen subspecialty and practice environment. Skills in the business of medicine, such as clinical billing, are widely applicable in academic and private practices but are not commonly addressed during formal medical education. Residency and fellowship training include limited exposure to medical billing, but our academic department's performance of these skills was inadequate: in 56% of trainee-generated outpatient notes, documentation was insufficient to sustain the chosen billing level. We developed a curriculum to improve the accuracy of documentation and coding and introduced practice changes to address our largest sources of error. In parallel, we developed tools that increased the speed and efficiency of documentation. Over 15 months, we progressively eliminated note devaluation, increased the mean level billed by trainees to nearly match that of attending physicians, and increased outpatient revenue by $34,313/trainee/year. Our experience suggests that inclusion of billing education topics into the formal medical curriculum benefits both academic medical centers and trainees.

Functional neurological symptom disorders in a pediatric emergency room: diagnostic accuracy, features, and outcome

BACKGROUND

In children, functional neurological symptom disorders are frequently the basis for presentation for emergency care. Pediatric epidemiological and outcome data remain scarce.

OBJECTIVE

Assess diagnostic accuracy of trainee's first impression in our pediatric emergency room; describe manner of presentation, demographic data, socioeconomic impact, and clinical outcomes, including parental satisfaction.

METHODS

(1) More than 1 year, psychiatry consultations for neurology patients with a functional neurological symptom disorder were retrospectively reviewed. (2) For 3 months, all children whose emergency room presentation suggested the diagnosis were prospectively collected. (3) Three to six months after prospective collection, families completed a structured telephone interview on outcome measures.

RESULTS

Twenty-seven patients were retrospectively assessed; 31 patients were prospectively collected. Trainees' accurately predicted the diagnosis in 93% (retrospective) and 94% (prospective) cohorts. Mixed presentations were most common (usually sensory-motor changes, e.g. weakness and/or paresthesias). Associated stressors were mundane and ubiquitous, rarely severe. Families were substantially affected, reporting mean symptom duration 7.4 (standard error of the mean ± 1.33) weeks, missing 22.4 (standard error of the mean ± 5.47) days of school, and 8.3 (standard error of the mean ± 2.88) of parental workdays (prospective cohort). At follow-up, 78% were symptom free. Parental dissatisfaction was rare, attributed to poor rapport and/or insufficient information conveyed.

CONCLUSIONS

Trainees' clinical impression was accurate in predicting a later diagnosis of functional neurological symptom disorder. Extraordinary life stressors are not required to trigger the disorder in children. Although prognosis is favorable, families incur substantial economic burden and negative educational impact. Improving recognition and appropriately communicating the diagnosis may speed access to treatment and potentially reduce the disability and cost of this disorder.

Acute dyskinetic reaction in a healthy toddler following methylphenidate ingestion

BACKGROUND

Acute dyskinetic or dystonic reactions are a long-recognized complication of medications that alter dopamine signaling. Most reactions occur following exposure to agents that block dopamine receptors (e.g., neuroleptics). However, agents that increase dopaminergic transmission (such as methylphenidate) can also trigger acute dyskinesias. This has been previously reported only in patients also taking dopamine antagonists or, less commonly, in children with developmental abnormalities.

CASE DESCRIPTION

The present report describes a previously healthy toddler who developed transient torticollis and orolingual dyskinesias following accidental exposure to methylphenidate. He had no preexisting movement disorder, central nervous system injury, or developmental abnormalities--in short, none of the previously reported risk factors for this side effect.

HYPOTHESIS AND CONCLUSIONS

The unique features of this case led to the hypothesis that developmental shifts in dopamine signaling were the basis for his particular sensitivity to methylphenidate. If confirmed, this hypothesis has implications for the treatment of common childhood attentional and behavioral disorders. The article includes a literature review of dyskinetic/dystonic reactions in children and the developmental regulation of dopamine metabolism.

Juvenile Huntington disease exacerbated by methylphenidate: case report

The authors describe the case of an 8-year-old boy, otherwise healthy, who presented with symptoms consistent with attention-deficit hyperactivity disorder (ADHD) and was started on a trial of methylphenidate. Within 4 weeks, he experienced a rapid decline in fine motor skills, with dysarthria, intention tremor, motor impersistence, and diffusely increased tone. Symptoms persisted despite cessation of methylphenidate. At that time, a paternal history of Huntington disease was disclosed. Molecular analysis revealed an expansion in CAG repeats to 75 copies, within the range characteristic of juvenile Huntington disease. This report raises the possibility that use of dopaminergic agonists in patients with a family history of Huntington disease may lead to clinical exacerbation of motor symptoms and/or unwitting diagnosis in an unprepared family.

Regional, cellular, and subcellular localization of RGS10 in rodent brain

The regulator of G protein signaling type 10 (RGS10) modulates Galphai/o signaling by means of its GTPase accelerating activity and is abundantly expressed in brain and in immune tissues. To elucidate RGS10 function in the nervous system, we mapped RGS10 protein in rat and mouse brain using light microscopic (LM) and electron microscopic (EM) immunohistochemical techniques. The LM showed that RGS10-like immunoreactivity (LIR) labels all cellular subcompartments of neurons and microglia, including their nuclei. There were several differences between RGS10-LIR distributions in rat and mouse, the most striking of which were the far denser immunoreactivity in rat dentate gyrus and dorsal raphe. The EM analysis corroborated and extended our findings from LM. Thus, EM confirmed the presence of dense RGS10-LIR in the euchromatin compartment of nuclei. The EM analysis also resolved dense staining on terminals at symmetric synapses onto pyramidal cell somata. Dual immunofluorescence showed that forebrain interneurons densely labeled with RGS10-LIR partially colocalized with parvalbumin-LIR. Dual-labeling histochemistry in caudoputamen demonstrated that densely labeled striatal cells were biased to the indirect-projecting output pathway. Dual-labeling immunofluorescence also showed that densely labeled RGS10-LIR cells in the dentate gyrus subgranular zone were not proliferating but that newly born cells could differentiate to express RGS10-LIR. Taken together, these data support a role for RGS10 in diverse processes that include modulation of pre- and postsynaptic G-protein signaling. Moreover, enrichment of RGS10 in transcriptionally active regions of the nucleus suggests an unforeseen role of RGS10 in modulating gene expression.