Network localization of hemichorea-hemiballismus

Clinical Reasoning: A 38-Year-Old Woman Presenting With Acute Hyperkinetic Movements of Her Right Arm

We present a case report of a 38-year-old woman who presented to the hospital with acute onset high amplitude, non-rhythmic, hyperkinetic movements of the right upper extremity, abnormal sensation of the right upper extremity from the elbow to the hand, and the inability to recognize her hand without visual input. This case discusses the differential diagnoses of acute hyperkinetic movement disorders and concurrent alien-limb in a patient presenting within the time window for vascular intervention. Readers are led through the reasoning behind acute interventional decision-making in a patient with a rare presentation. Workup reveals the eventual diagnosis.

Brain Structural and Functional Damage Network Localization of Suicide

BACKGROUND

Extensive neuroimaging research on brain structural and functional correlates of suicide has produced inconsistent results. Despite increasing recognition that damage in multiple different brain locations that causes the same symptom can map to a common brain network, there is still a paucity of research investigating network localization of suicide.

METHODS

To clarify this issue, we initially identified brain structural and functional damage locations in relation to suicide from 63 published studies with 2135 suicidal and 2606 nonsuicidal individuals. By applying novel functional connectivity network mapping to large-scale discovery and validation resting-state functional magnetic resonance imaging datasets, we mapped these affected brain locations to 3 suicide brain damage networks corresponding to different imaging modalities.

RESULTS

The suicide gray matter volume damage network comprised widely distributed brain areas primarily involving the dorsal default mode, basal ganglia, and anterior salience networks. The suicide task-induced activation damage network was similar to but less extensive than the gray matter volume damage network, predominantly implicating the same canonical networks. The suicide resting-state activity damage network manifested as a localized set of brain regions encompassing the orbitofrontal cortex and middle cingulate cortex.

CONCLUSIONS

Our findings not only may help reconcile prior heterogeneous neuroimaging results, but also may provide insights into the neurobiological mechanisms of suicide from a network perspective, which may ultimately inform more targeted and effective strategies to prevent suicide.

Localization of stuttering based on causal brain lesions

Stuttering affects approximately 1 in 100 adults and can result in significant communication problems and social anxiety. It most often occurs as a developmental disorder but can also be caused by focal brain damage. These latter cases may lend unique insight into the brain regions causing stuttering. Here, we investigated the neuroanatomical substrate of stuttering using three independent datasets: (i) case reports from the published literature of acquired neurogenic stuttering following stroke (n = 20, 14 males/six females, 16-77 years); (ii) a clinical single study cohort with acquired neurogenic stuttering following stroke (n = 20, 13 males/seven females, 45-87 years); and (iii) adults with persistent developmental stuttering (n = 20, 14 males/six females, 18-43 years). We used the first two datasets and lesion network mapping to test whether lesions causing acquired stuttering map to a common brain network. We then used the third dataset to test whether this lesion-based network was relevant to developmental stuttering. In our literature dataset, we found that lesions causing stuttering occurred in multiple heterogeneous brain regions, but these lesion locations were all functionally connected to a common network centred around the left putamen, including the claustrum, amygdalostriatal transition area and other adjacent areas. This finding was shown to be specific for stuttering (PFWE < 0.05) and reproducible in our independent clinical cohort of patients with stroke-induced stuttering (PFWE < 0.05), resulting in a common acquired stuttering network across both stroke datasets. Within the common acquired stuttering network, we found a significant association between grey matter volume and stuttering impact for adults with persistent developmental stuttering in the left posteroventral putamen, extending into the adjacent claustrum and amygdalostriatal transition area (PFWE < 0.05). We conclude that lesions causing acquired neurogenic stuttering map to a common brain network, centred to the left putamen, claustrum and amygdalostriatal transition area. The association of this lesion-based network with symptom severity in developmental stuttering suggests a shared neuroanatomy across aetiologies.

Abnormal supplementary motor areas are associated with idiopathic and acquired blepharospasm

Blepharospasm is a common form of focal dystonia characterized by excessive and involuntary spasms of the orbicularis oculi. In addition to idiopathic blepharospasm, lesions in various brain regions can also cause acquired blepharospasm. Whether these two types of blepharospasm share a common brain network remains largely unknown. Herein, we performed lesion coactivation network mapping, based on meta-analytic connectivity modeling, to test whether lesions causing blepharospasm could be mapped to a common coactivation brain network. We then tested the abnormality of the network in patients with idiopathic blepharospasm (n = 42) compared with healthy controls (n = 44). We identified 21 cases of lesion-induced blepharospasms through a systematic literature search. Although these lesions were heterogeneous, they were part of a co-activated brain network that mainly included the bilateral supplementary motor areas. Coactivation of these regions defines a single brain network that encompasses or is adjacent to most heterogeneous lesions causing blepharospasm. Moreover, the bilateral supplementary motor area is primarily associated with action execution, visual motion, and imagination, and participates in finger tapping and saccades. They also reported decreased functional connectivity with the left posterior cingulate cortex in patients with idiopathic blepharospasm. These results demonstrate a common convergent abnormality of the supplementary motor area across idiopathic and acquired blepharospasms, providing additional evidence that the supplementary motor area is an important brain region that is pathologically impaired in patients with blepharospasm.

Diabetic striatopathy and other acute onset de novo movement disorders in hyperglycemia

BACKGROUND AND AIMS

Acute onset de novo movement disorder is an increasingly recognized, yet undereported complication of diabetes. Hyperglycemia can give rise to a range of different movement disorders, hemichorea-hemiballism being the commonest. This article delves into the current knowledge about this condition, its diverse presentations, ongoing debates regarding its underlying mechanisms, disparities between clinical and radiological findings, and challenges related to its management.

METHODS

PubMed and Google Scholar were searched with the following key terms- "diabetes", "striatopathy", "hyperglycemia", "striatum", "basal ganglia", "movement disorder", "involuntary movement". Case reports, systematic reviews, meta-analysis, and narrative reviews published in English literature related to the topic of interest from January 1, 1950, to October 20, 2023, were retrieved. The references cited in the chosen articles were also examined, and those considered relevant were included in the review.

RESULTS

Diabetic striatopathy is the prototype of movement disorders associated with hyperglycemia with its characteristic neuroimaging feature (contralateral striatal hyperdensitity on computed tomography or hyperintensity on T1-weighted magnetic resonance imaging). Risk factors for diabetic striatopathy includes Asian ethnicity, female gender, prolonged poor glycemic control, and concurrent retinopathy. Several hypotheses have been proposed to explain the pathophysiology of movement disorders induced by hyperglycemia. These hypotheses are not mutually exclusive; instead, they represent interconnected pathways contributing to the development of this unique condition. While the most prominent clinical feature of diabetic striatopathy is a movement disorder, its phenotypic expression has been found to extend to other manifestations, including stroke, seizures, and cognitive and behavioral symptoms. Fortunately, the prognosis for diabetic striatopathy is generally excellent, with complete resolution achievable through the use of anti-hyperglycemic therapy alone or in combination with neuroleptic medications.

CONCLUSION

Hyperglycemia is the commonest cause of acute onset de novo movement disorders presenting to a range of medical specialists. So, it is of utmost importance that the physicians irrespective of their speciality remain aware of this clinical entity and check blood glucose at presentation before ordering any other investigations. Prompt clinical diagnosis of this condition and implementation of intensive glycemic control can yield significant benefits for patients.

Network Localization of State and Trait of Auditory Verbal Hallucinations in Schizophrenia

BACKGROUND AND HYPOTHESIS

Neuroimaging studies investigating the neural substrates of auditory verbal hallucinations (AVH) in schizophrenia have yielded mixed results, which may be reconciled by network localization. We sought to examine whether AVH-state and AVH-trait brain alterations in schizophrenia localize to common or distinct networks.

STUDY DESIGN

We initially identified AVH-state and AVH-trait brain alterations in schizophrenia reported in 48 previous studies. By integrating these affected brain locations with large-scale discovery and validation resting-state functional magnetic resonance imaging datasets, we then leveraged novel functional connectivity network mapping to construct AVH-state and AVH-trait dysfunctional networks.

STUDY RESULTS

The neuroanatomically heterogeneous AVH-state and AVH-trait brain alterations in schizophrenia localized to distinct and specific networks. The AVH-state dysfunctional network comprised a broadly distributed set of brain regions mainly involving the auditory, salience, basal ganglia, language, and sensorimotor networks. Contrastingly, the AVH-trait dysfunctional network manifested as a pattern of circumscribed brain regions principally implicating the caudate and inferior frontal gyrus. Additionally, the AVH-state dysfunctional network aligned with the neuromodulation targets for effective treatment of AVH, indicating possible clinical relevance.

CONCLUSIONS

Apart from unifying the seemingly irreproducible neuroimaging results across prior AVH studies, our findings suggest different neural mechanisms underlying AVH state and trait in schizophrenia from a network perspective and more broadly may inform future neuromodulation treatment for AVH.

Hemichorea in patients with temporal lobe infarcts: Two case reports

BACKGROUND

Hemichorea and other hyperkinetic movement disorders are uncommon presentations of stroke and are usually secondary to deep infarctions affecting the basal ganglia and thalamus. Therefore, temporal ischemic lesions causing hemichorea are rare. We report the cases of two patients with acute ischemic temporal lobe infarct strokes that presented as hemichorea.

CASE SUMMARY

Patient 1: An 82-year-old woman presented with a 1-mo history of involuntary movement of the left extremity, which was consistent with hemichorea. Her diffusion-weighted imaging (DWI) revealed an acute ischemic stroke that predominantly affected the right temporal cortex, and magnetic resonance angiography of the head showed significant stenosis of the right middle cerebral artery (MCA). Treatment with 2.5 mg of olanzapine per day was initiated. When she was discharged from the hospital, her symptoms appeared to have improved compared with those previously observed. Twenty-seven days after the first admission, she was readmitted due to acute ischemic stroke. Computed tomography perfusion showed marked hypoperfusion in the right MCA territory. An emergency transfemoral cerebral angiogram was performed and showed severe stenosis in the M1 segment of the right MCA. After percutaneous transluminal angioplasty was successfully performed, abnormal movements or other neurologic problems did not occur. Patient 2: A 76-year-old man was admitted to our hospital for a 7-d history of right-upper-sided involuntary movements. DWI showed an acute patchy ischemic stroke in the left temporal lobe without basal ganglia involvement. Subsequent diffusion tensor imaging confirmed fewer white matter fiber tracts on the left side than on the opposite side. Treatment with 2.5 mg of olanzapine per day improved his condition, and he was discharged.

CONCLUSION

When acute hemichorea suddenly appears, temporal cortical ischemic stroke should be considered a possible diagnosis. In addition, hemichorea may be a sign of impending cerebral infarction with MCA stenosis.

Footloose (footloose), footloose

A 78-year-old woman without past relevant medical history presented to the emergency department for acute transient dysarthria. NIHSS was 0/42. Neurological examination revealed chorea-like movements over the left limbs, especially the foot. No other neurological signs were present. CT perfusion showed right cortical hypoperfusion due to right M2 occlusion, basal-ganglia perfusion was normal. Brain MRI revealed a small focus of restricted diffusion in the right insula, sparing basal ganglia. Based on the neuroimaging features and clinical correlation, despite the NIHSS score, we decided to treat the patient with alteplase, after iv-thrombolysis hyperkinetic movements ceased completely. Brain-MRI performed 72 h after symptom onset confirmed a confined insular ischemic lesion without the involvement of deep gray matter structures. Hyperkinetic movement disorders, such as hemichorea hemiballismus, are rare presentations of stroke, basal ganglia are mainly involved even if the insular cortex has been described too. Clinical decision on whether to treat ischemic stroke does not include movement disorders. Our case underscores NIHSS limitations in clinical practice.

A neural circuit for spatial orientation derived from brain lesions

There is disagreement regarding the major components of the brain network supporting spatial cognition. To address this issue, we applied a lesion mapping approach to the clinical phenomenon of topographical disorientation. Topographical disorientation is the inability to maintain accurate knowledge about the physical environment and use it for navigation. A review of published topographical disorientation cases identified 65 different lesion sites. Our lesion mapping analysis yielded a topographical disorientation brain map encompassing the classic regions of the navigation network: medial parietal, medial temporal, and temporo-parietal cortices. We also identified a ventromedial region of the prefrontal cortex, which has been absent from prior descriptions of this network. Moreover, we revealed that the regions mapped are correlated with the Default Mode Network sub-network C. Taken together, this study provides causal evidence for the distribution of the spatial cognitive system, demarking the major components and identifying novel regions.

Acute Caudate Nucleus Stroke Presenting As Hemiballismus

Hemiballismus is defined as irregular, involuntary, large-amplitude flinging movements by the limbs, confined to one side of the body. Hemichorea refers to a state of excessive and irregularly timed, non-repetitive and randomly distributed, spontaneous, involuntary, and abrupt movements. It is widely believed that hemiballismus and chorea are suggestive of a lesion to the basal ganglia and subthalamic nucleus (STN). However, there are other etiologies that may influence the clinical presentation. Patients may present with certain common clinical features corresponding to the affected area of the brain. For example, infarctions of the motor cortex present with hemiplegia or paralysis of one side of the body. Similarly, infarctions involving the language areas of the brain present with aphasia and are detrimental to speech production or comprehension and the ability to read and write. Typically, acute-onset hemichorea is suggestive of a lesion in the STN. Herein, we present a rare case of acute hemiballismus and hemichorea following infarction of the left caudate nucleus, as determined by magnetic resonance imaging (MRI) and computerized tomography (CT) imaging modalities.

Lesion network mapping of eye-opening apraxia

Apraxia of eyelid opening (or eye-opening apraxia) is characterized by the inability to voluntarily open the eyes because of impaired supranuclear control. Here, we examined the neural substrates implicated in eye-opening apraxia through lesion network mapping. We analysed brain lesions from 27 eye-opening apraxia stroke patients and compared them with lesions from 20 aphasia and 45 hemiballismus patients serving as controls. Lesions were mapped onto a standard brain atlas using resting-state functional MRI data derived from 966 healthy adults in the Harvard Dataverse. Our analyses revealed that most eye-opening apraxia-associated lesions occurred in the right hemisphere, with subcortical or mixed cortical/subcortical involvement. Despite their anatomical heterogeneity, these lesions functionally converged on the bilateral dorsal anterior and posterior insula. The functional connectivity map for eye-opening apraxia was distinct from those for aphasia and hemiballismus. Hemiballismus lesions predominantly mapped onto the putamen, particularly the posterolateral region, while aphasia lesions were localized to language-processing regions, primarily within the frontal operculum. In summary, in patients with eye-opening apraxia, disruptions in the dorsal anterior and posterior insula may compromise their capacity to initiate the appropriate eyelid-opening response to relevant interoceptive and exteroceptive stimuli, implicating a complex interplay between salience detection and motor execution.

Network Localization of Spontaneous Confabulation

OBJECTIVE

Spontaneous confabulation is a symptom in which false memories are conveyed by the patient as true. The purpose of the study was to identify the neuroanatomical substrate of this complex symptom and evaluate the relationship to related symptoms, such as delusions and amnesia.

METHODS

Twenty-five lesion locations associated with spontaneous confabulation were identified in a systematic literature search. The network of brain regions functionally connected to each lesion location was identified with a large connectome database (N=1,000) and compared with networks derived from lesions associated with nonspecific (i.e., variable) symptoms (N=135), delusions (N=32), or amnesia (N=53).

RESULTS

Lesions associated with spontaneous confabulation occurred in multiple brain locations, but they were all part of a single functionally connected brain network. Specifically, 100% of lesions were connected to the mammillary bodies (familywise error rate [FWE]-corrected p<0.05). This connectivity was specific for lesions associated with confabulation compared with lesions associated with nonspecific symptoms or delusions (FWE-corrected p<0.05). Lesions associated with confabulation were more connected to the orbitofrontal cortex than those associated with amnesia (FWE-corrected p<0.05).

CONCLUSIONS

Spontaneous confabulation maps to a common functionally connected brain network that partially overlaps, but is distinct from, networks associated with delusions or amnesia. These findings lend new insight into the neuroanatomical bases of spontaneous confabulation.

Functional and structural lesion network mapping in neurological and psychiatric disorders: a systematic review

Background

The traditional approach to studying the neurobiological mechanisms of brain disorders and localizing brain function involves identifying brain abnormalities and comparing them to matched controls. This method has been instrumental in clinical neurology, providing insight into the functional roles of different brain regions. However, it becomes challenging when lesions in diverse regions produce similar symptoms. To address this, researchers have begun mapping brain lesions to functional or structural networks, a process known as lesion network mapping (LNM). This approach seeks to identify common brain circuits associated with lesions in various areas. In this review, we focus on recent studies that have utilized LNM to map neurological and psychiatric symptoms, shedding light on how this method enhances our understanding of brain network functions.

Methods

We conducted a systematic search of four databases: PubMed, Scopus, and Web of Science, using the term "Lesion network mapping." Our focus was on observational studies that applied lesion network mapping in the context of neurological and psychiatric disorders.

Results

Following our screening process, we included 52 studies, comprising a total of 6,814 subjects, in our systematic review. These studies, which utilized functional connectivity, revealed several regions and network overlaps across various movement and psychiatric disorders. For instance, the cerebellum was found to be part of a common network for conditions such as essential tremor relief, parkinsonism, Holmes tremor, freezing of gait, cervical dystonia, infantile spasms, and tics. Additionally, the thalamus was identified as part of a common network for essential tremor relief, Holmes tremor, and executive function deficits. The dorsal attention network was significantly associated with fall risk in elderly individuals and parkinsonism.

Conclusion

LNM has proven to be a powerful tool in localizing a broad range of neuropsychiatric, behavioral, and movement disorders. It holds promise in identifying new treatment targets through symptom mapping. Nonetheless, the validity of these approaches should be confirmed by more comprehensive prospective studies.

Deep Brain Stimulation for the Treatment of Hemichorea: Case Series and Literature Review

Background

Hemichorea (HC) and its severe form hemiballismus (HB) are rare movement disorders which can be medically refractory to treatments and may need surgical intervention.

Case Report

We report 3 patients with HC-HB who had meaningful clinical improvement with unilateral deep brain stimulation (DBS) of the globus pallidus interna (GPi). We identified 8 prior cases of HC-HB treated with GPi-DBS, and a majority of these patients experienced significant improvement in their symptoms.

Discussion

GPi-DBS can be considered in medically refractory HC-HB in carefully selected patients. However, data is limited to small case series and further studies are needed.

Hemichorea secondary to isolated temporal infarction with severe middle cerebral artery stenosis: a case report and review of literature

BACKGROUND

Hemichorea typically results from a contralateral subthalamic nuclei (STN) lesion, although it has been reported in the cortex in a minority of cases. However, to our best knowledge, there are no documented cases in literature of hemichorea occurring as a secondary condition to an isolated temporal stroke.

CASE PRESENTATION

We present a case of an elderly female who sustained a sudden onset of hemichorea in her right extremities, predominantly in the distal region, lasting over a period of two days. Brain diffuse weighted image (DWI) demonstrated a high signal in the temporal region, while magnetic resonance angiography (MRA) revealed severe stenosis of the middle cerebral artery. During the symptomatic phase, computed tomography perfusion (CTP) revealed delayed perfusion in the left middle cerebral artery territory, characterized by the time-to-peak (TTP) measure. Based on the results of her medical history and laboratory tests, we were able to rule out the possibility of infectious, toxic, or metabolic encephalopathy. Her symptoms gradually improved with antithrombotic and symptomatic treatment.

CONCLUSIONS

It is important to recognize and consider acute onset hemichorea as an initial symptom of stroke to avoid misdiagnosis and delays in appropriate treatment. Further research on temporal lesion that lead to hemichorea is warranted to gain a better understanding of the underlying mechanisms.

Investigation of the factors associated with hemichorea/hemiballismus in post-stroke patients

Classical knowledge highlights the role of lesions of the subthalamic nuclei (STN) in the pathophysiology of hemichorea/hemiballismus (HH). However, the published reports indicate various other lesion regions in the majority of post-stroke cases with HH. Ergo, we aimed to investigate the significance of the lesion site and clinical features for developing HH in post-stroke patients. Overall, we retrospectively scanned all the patients with stroke who were hospitalized between 01/06/2022 and 31/07/2022 in our neurology clinic. The data regarding the demographic features, comorbidities, stroke etiologies, and laboratory findings, including serum glucose and HBA1C were retrospectively recruited using the electronic-based medical record system. The cranial magnetic resonance imaging (MRI) and computed tomography images have been systematically evaluated for the presence of lesions in localizations that are previously associated with HH. We conducted comparative analyses between patients with and without HH to reveal the discrepancies between groups. The logistic regression analyses were also performed to reveal the predictive values of some features. Overall, the data of 124 post-stroke patients were analyzed. The mean age was 67.9 ± 12.4 years (F/M = 57/67). Six patients were determined to develop HH. The comparative analyses between patients with and without HH revealed that the mean age tended to be higher in the HH group (p = 0.08) and caudate nucleus involvement was more common in the HH group (p = 0.005). Besides cortical involvement was absent in all subjects developing HH. The logistic regression model revealed the presence of a caudate lesion and advanced age as factors associated with HH. We found that the caudate lesion was a crucial determinant of the occurrence of HH in post-stroke patients. With the significance of the other factors of increased age and cortical sparring, we observed differences in the HH group may be investigated also in future-related studies on larger groups.

Diagnostic Uncertainties: Chorea

Chorea is a hyperkinetic movement disorder with a multitude of potential etiologies, both acquired and inherited. Although the differential diagnosis for new-onset chorea is extensive, there are often clues in the history, exam, and basic testing that can help to narrow the options. Evaluation for treatable or reversible causes should take priority, as rapid diagnosis can lead to more favorable outcomes. While Huntington's disease is most common genetic cause of chorea, multiple phenocopies also exist and should be considered if Huntington gene testing is negative. The decision of what additional genetic testing to pursue should be based on both clinical and epidemiological factors. The following review provides an overview of the many possible etiologies as well as a practical approach for a patient presenting with new-onset chorea.

Neuroanatomical Localization of Rapid Eye Movement Sleep Behavior Disorder in Human Brain Using Lesion Network Mapping

OBJECTIVE

To localize the neuroanatomical substrate of rapid eye movement sleep behavior disorder (RBD) and to investigate the neuroanatomical locational relationship between RBD and α-synucleinopathy neurodegenerative diseases.

MATERIALS AND METHODS

Using a systematic PubMed search, we identified 19 patients with lesions in different brain regions that caused RBD. First, lesion network mapping was applied to confirm whether the lesion locations causing RBD corresponded to a common brain network. Second, the literature-based RBD lesion network map was validated using neuroimaging findings and locations of brain pathologies at post-mortem in patients with idiopathic RBD (iRBD) who were identified by independent systematic literature search using PubMed. Finally, we assessed the locational relationship between the sites of pathological alterations at the preclinical stage in α-synucleinopathy neurodegenerative diseases and the brain network for RBD.

RESULTS

The lesion network mapping showed lesions causing RBD to be localized to a common brain network defined by connectivity to the pons (including the locus coeruleus, dorsal raphe nucleus, central superior nucleus, and ventrolateral periaqueductal gray), regardless of the lesion location. The positive regions in the pons were replicated by the neuroimaging findings in an independent group of patients with iRBD and it coincided with the reported pathological alterations at post-mortem in patients with iRBD. Furthermore, all brain pathological sites at preclinical stages (Braak stages 1-2) in Parkinson's disease (PD) and at brainstem Lewy body disease in dementia with Lewy bodies (DLB) were involved in the brain network identified for RBD.

CONCLUSION

The brain network defined by connectivity to positive pons regions might be the regulatory network loop inducing RBD in humans. In addition, our results suggested that the underlying cause of high phenoconversion rate from iRBD to neurodegenerative α-synucleinopathy might be pathological changes in the preclinical stage of α-synucleinopathy located at the regulatory network loop of RBD.

Hypoglycemic Encephalopathy Manifesting with Cortical Hemichorea-Hemiballismus Syndrome: A Case Report

Hyper-/hypoglycemic states are rare but well-established causes of hyperkinetic movements, including chorea and ballismus, usually associated with brain lesions in the basal ganglia. We report a case of hemichorea-hemiballismus (HCHB) syndrome that developed after a severe hypoglycemic episode in a 71-year-old man with poorly controlled type 2 diabetes mellitus. Uncommonly, brain MRI showed contralateral cortical-subcortical T2 and T2-FLAIR-hyperintense frontoparietal lesions, with cingulate gyrus involved, while the basal ganglia were unaffected. In patients with hypoglycemic encephalopathy associated with cortical lesions, the long-term prognosis is usually poor. Nevertheless, in our patient, the dyskinesias and the cerebral lesions progressively regressed by achieving good glycemic control. After four and 12 months, the patient's neurological examination was normal. To our knowledge, this is the first evidence of hypoglycemic etiology of cortical HCHB syndrome, supporting recent theories that cortical circuitries may independently contribute to the pathogenesis of chorea and ballismus. This is also the first report of cingulate gyrus involvement in hypoglycemic encephalopathy. Finally, this case may indicate that a subset of patients with cortical lesions due to hypoglycemia could present a good clinical outcome, likely depending on the size of the lesions and the duration and severity of the hypoglycemic episode.

Dysfunctional cerebello-cerebral network associated with vocal emotion recognition impairments

Vocal emotion recognition, a key determinant to analyzing a speaker's emotional state, is known to be impaired following cerebellar dysfunctions. Nevertheless, its possible functional integration in the large-scale brain network subtending emotional prosody recognition has yet to be explored. We administered an emotional prosody recognition task to patients with right versus left-hemispheric cerebellar lesions and a group of matched controls. We explored the lesional correlates of vocal emotion recognition in patients through a network-based analysis by combining a neuropsychological approach for lesion mapping with normative brain connectome data. Results revealed impaired recognition among patients for neutral or negative prosody, with poorer sadness recognition performances by patients with right cerebellar lesion. Network-based lesion-symptom mapping revealed that sadness recognition performances were linked to a network connecting the cerebellum with left frontal, temporal, and parietal cortices. Moreover, when focusing solely on a subgroup of patients with right cerebellar damage, sadness recognition performances were associated with a more restricted network connecting the cerebellum to the left parietal lobe. As the left hemisphere is known to be crucial for the processing of short segmental information, these results suggest that a corticocerebellar network operates on a fine temporal scale during vocal emotion decoding.

Multimodal and multidomain lesion network mapping enhances prediction of sensorimotor behavior in stroke patients

Beyond the characteristics of a brain lesion, such as its etiology, size or location, lesion network mapping (LNM) has shown that similar symptoms after a lesion reflects similar dis-connectivity patterns, thereby linking symptoms to brain networks. Here, we extend LNM by using a multimodal strategy, combining functional and structural networks from 1000 healthy participants in the Human Connectome Project. We apply multimodal LNM to a cohort of 54 stroke patients with the aim of predicting sensorimotor behavior, as assessed through a combination of motor and sensory tests. Results are two-fold. First, multimodal LNM reveals that the functional modality contributes more than the structural one in the prediction of sensorimotor behavior. Second, when looking at each modality individually, the performance of the structural networks strongly depended on whether sensorimotor performance was corrected for lesion size, thereby eliminating the effect that larger lesions generally produce more severe sensorimotor impairment. In contrast, functional networks provided similar performance regardless of whether or not the effect of lesion size was removed. Overall, these results support the extension of LNM to its multimodal form, highlighting the synergistic and additive nature of different types of network modalities, and their corresponding influence on behavioral performance after brain injury.

Lesions causing post-stroke spasticity localize to a common brain network

Objective

The efficacy of clinical interventions for post-stroke spasticity (PSS) has been consistently unsatisfactory, probably because lesions causing PSS may occur at different locations in the brain, leaving the neuroanatomical substrates of spasticity unclear. Here, we investigated whether heterogeneous lesions causing PSS were localized to a common brain network and then identified the key nodes in this network.

Methods

We used 32 cases of PSS and the Human Connectome dataset (n = 1,000), using a lesion network mapping method to identify the brain regions that were associated with each lesion in patients with PSS. Functional connectivity maps of all lesions were overlaid to identify common connectivity. Furthermore, a split-half replication method was used to evaluate reproducibility. Then, the lesion network mapping results were compared with those of patients with post-stroke non-spastic motor dysfunction (n = 29) to assess the specificity. Next, both sensitive and specific regions associated with PSS were identified using conjunction analyses, and the correlation between these regions and PSS was further explored by correlation analysis.

Results

The lesions in all patients with PSS were located in different cortical and subcortical locations. However, at least 93% of these lesions (29/32) had functional connectivity with the bilateral putamen and globus pallidus. These connections were highly repeatable and specific, as compared to those in non-spastic patients. In addition, the functional connectivity between lesions and bilateral putamen and globus pallidus in patients with PSS was positively correlated with the degree of spasticity.

Conclusion

We identified that lesions causing PSS were localized to a common functional connectivity network defined by connectivity to the bilateral putamen and globus pallidus. This network may best cover the locations of lesions causing PSS. The putamen and globus pallidus may be potential key regions in PSS. Our findings complement previous neuroimaging studies on PSS, contributing to identifying patients with stroke at high risk for spasticity at an early stage, and may point to PSS-specific brain stimulation targets.

Activation network mapping for integration of heterogeneous fMRI findings

Functional neuroimaging techniques have been widely used to probe the neural substrates of facial emotion processing in healthy people. However, findings are largely inconsistent across studies. Here, we introduce a new technique termed activation network mapping to examine whether heterogeneous functional magnetic resonance imaging findings localize to a common network for emotion processing. First, using the existing method of activation likelihood estimation meta-analysis, we showed that individual-brain-based reproducibility was low across studies. Second, using activation network mapping, we found that network-based reproducibility across these same studies was higher. Validation analysis indicated that the activation network mapping-localized network aligned with stimulation sites, structural abnormalities and brain lesions that disrupt facial emotion processing. Finally, we verified the generality of the activation network mapping technique by applying it to another cognitive process, that is, rumination. Activation network mapping may potentially be broadly applicable to localize brain networks of cognitive functions.

A precise language network revealed by the independent component-based lesion mapping in post-stroke aphasia

Brain lesion mapping studies have provided the strongest evidence regarding the neural basis of cognition. However, it remained a problem to identify symptom-specific brain networks accounting for observed clinical and neuroanatomical heterogeneity. Independent component analysis (ICA) is a statistical method that decomposes mixed signals into multiple independent components. We aimed to solve this issue by proposing an independent component-based lesion mapping (ICLM) method to identify the language network in patients with moderate to severe post-stroke aphasia. Lesions were first extracted from 49 patients with post-stroke aphasia as masks applied to fMRI data in a cohort of healthy participants to calculate the functional connectivity (FC) within the masks and non-mask brain voxels. ICA was further performed on a reformatted FC matrix to extract multiple independent networks. Specifically, we found that one of the lesion-related independent components (ICs) highly resembled classical language networks. Moreover, the damaged level within the language-related lesioned network is strongly associated with language deficits, including aphasia quotient, naming, and auditory comprehension scores. In comparison, none of the other two traditional lesion mapping methods found any regions responsible for language dysfunction. The language-related lesioned network extracted with the ICLM method showed high specificity in detecting aphasia symptoms compared with the performance of resting ICs and classical language networks. In total, we detected a precise language network in patients with aphasia and proved its efficiency in the relationship with language symptoms. In general, our ICLM could successfully identify multiple lesion-related networks from complicated brain diseases, and be used as an effective tool to study brain-behavior relationships and provide potential biomarkers of particular clinical behavioral deficits.

Lesion network mapping for symptom localization: recent developments and future directions

PURPOSE OF REVIEW

Focal lesions causing specific neurological or psychiatric symptoms can occur in multiple different brain locations, complicating symptom localization. Here, we review lesion network mapping, a technique used to aid localization by mapping lesion-induced symptoms to brain circuits rather than individual brain regions. We highlight recent examples of how this technique is being used to investigate clinical entities and identify therapeutic targets.

RECENT FINDINGS

To date, lesion network mapping has successfully been applied to more than 40 different symptoms or symptom complexes. In each case, lesion locations were combined with an atlas of human brain connections (the human connectome) to map heterogeneous lesion locations causing the same symptom to a common brain circuit. This approach has lent insight into symptoms that have been difficult to localize using other techniques, such as hallucinations, tics, blindsight, and pathological laughter and crying. Further, lesion network mapping has recently been applied to lesions that improve symptoms, such as tremor and addiction, which may translate into new therapeutic targets.

SUMMARY

Lesion network mapping can be used to map lesion-induced symptoms to brain circuits rather than single brain regions. Recent findings have provided insight into long-standing clinical mysteries and identified testable treatment targets for circuit-based and symptom-based neuromodulation.

Neural substrates of motivational dysfunction across neuropsychiatric conditions: Evidence from meta-analysis and lesion network mapping

Motivational dysfunction constitutes one of the fundamental dimensions of psychopathology cutting across traditional diagnostic boundaries. However, it is unclear whether there is a common neural circuit responsible for motivational dysfunction across neuropsychiatric conditions. To address this issue, the current study combined a meta-analysis on psychiatric neuroimaging studies of reward/loss anticipation and consumption (4308 foci, 438 contrasts, 129 publications) with a lesion network mapping approach (105 lesion cases). Our meta-analysis identified transdiagnostic hypoactivation in the ventral striatum (VS) for clinical/at-risk conditions compared to controls during the anticipation of both reward and loss. Moreover, the VS subserves a key node in a distributed brain network which encompasses heterogeneous lesion locations causing motivation-related symptoms. These findings do not only provide the first meta-analytic evidence of shared neural alternations linked to anticipatory motivation-related deficits, but also shed novel light on the role of VS dysfunction in motivational impairments in terms of both network integration and psychological functions. Particularly, the current findings suggest that motivational dysfunction across neuropsychiatric conditions is rooted in disruptions of a common brain network anchored in the VS, which contributes to motivational salience processing rather than encoding positive incentive values.

Lesion network mapping of mania using different normative connectomes

Lesion network mapping is a neuroimaging technique that explores the network of regions functionally connected to lesions causing a common syndrome. The technique uses resting state functional connectivity from large databases of healthy individuals, i.e., connectomes, and has allowed for important insight into the potential network mechanisms underlying several neuropsychiatric disorders. However, concerns regarding reproducibility have arisen, that may be due to the use of different connectomes, with variable MRI acquisition parameters and preprocessing methods. Here, we tested the impact of using different connectomes on the results of lesion network mapping for mania. We found results were reliable and consistent independent of the connectome used.

Causal mapping of human brain function

Mapping human brain function is a long-standing goal of neuroscience that promises to inform the development of new treatments for brain disorders. Early maps of human brain function were based on locations of brain damage or brain stimulation that caused a functional change. Over time, this approach was largely replaced by technologies such as functional neuroimaging, which identify brain regions in which activity is correlated with behaviours or symptoms. Despite their advantages, these technologies reveal correlations, not causation. This creates challenges for interpreting the data generated from these tools and using them to develop treatments for brain disorders. A return to causal mapping of human brain function based on brain lesions and brain stimulation is underway. New approaches can combine these causal sources of information with modern neuroimaging and electrophysiology techniques to gain new insights into the functions of specific brain areas. In this Review, we provide a definition of causality for translational research, propose a continuum along which to assess the relative strength of causal information from human brain mapping studies and discuss recent advances in causal brain mapping and their relevance for developing treatments.

Afternoon Tea Hemichorea

A 78 year old lady, with a past medical history of hypertension, presented to the Accident & Emergency department after a sudden onset of right sided involuntary movements while she was having afternoon tea with her friends. Examination showed isolated unilateral chorea, affecting the right arm and leg (video). Her blood glucose and sodium levels were normal. The MRI head scan showed a left globus pallidus infarct (figure 1). Tetrabenazine was prescribed with very good response, and weaned off after 4 weeks. Hyperkinetic movement disorders are uncommon in acute stroke (1%)1. Lesions in regions functionally connected to the posterolateral putamen are implicated in hyperkinetic movement disorders2. The differential diagnosis includes hyperglycaemia, hyponatraemia and drug-induced chorea. In cases of sudden onset, it is important to recognise stroke as a possible cause to avoid missing reperfusion therapy opportunities

Circuit-Targeted Neuromodulation for Anhedonia

Despite the prevalence of anhedonia across multiple psychiatric disorders, its relevance to treatment selection and prognostication can be unclear (Davey et al., Psychol Med 42(10):2071-81, 2012). Given the challenges in pharmacological and psychosocial treatment, there has been increasing attention devoted to neuroanatomically-targeted treatments. This chapter will present a brief introduction to circuit-targeted therapeutics in psychiatry (Sect. 1), an overview of brain mapping as it relates to anhedonia (Sect. 2), a review of existing studies on brain stimulation for anhedonia (Sect. 3), and a description of emerging approaches to circuit-based neuromodulation for anhedonia (Sect. 4).

Clinical applications of magnetic resonance imaging based functional and structural connectivity

Advances in computational neuroimaging techniques have expanded the armamentarium of imaging tools available for clinical applications in clinical neuroscience. Non-invasive, in vivo brain MRI structural and functional network mapping has been used to identify therapeutic targets, define eloquent brain regions to preserve, and gain insight into pathological processes and treatments as well as prognostic biomarkers. These tools have the real potential to inform patient-specific treatment strategies. Nevertheless, a realistic appraisal of clinical utility is needed that balances the growing excitement and interest in the field with important limitations associated with these techniques. Quality of the raw data, minutiae of the processing methodology, and the statistical models applied can all impact on the results and their interpretation. A lack of standardization in data acquisition and processing has also resulted in issues with reproducibility. This limitation has had a direct impact on the reliability of these tools and ultimately, confidence in their clinical use. Advances in MRI technology and computational power as well as automation and standardization of processing methods, including machine learning approaches, may help address some of these issues and make these tools more reliable in clinical use. In this review, we will highlight the current clinical uses of MRI connectomics in the diagnosis and treatment of neurological disorders; balancing emerging applications and technologies with limitations of connectivity analytic approaches to present an encompassing and appropriate perspective.

Post-Stroke Cognitive Impairment: Pathophysiological Insights into Brain Disconnectome from Advanced Neuroimaging Analysis Techniques

The neurological symptoms of stroke have traditionally provided the foundation for functional mapping of the brain. However, there are many unresolved aspects in our understanding of cerebral activity, especially regarding high-level cognitive functions. This review provides a comprehensive look at the pathophysiology of post-stroke cognitive impairment in light of recent findings from advanced imaging techniques. Combining network neuroscience and clinical neurology, our research focuses on how changes in brain networks correlate with post-stroke cognitive prognosis. More specifically, we first discuss the general consequences of stroke lesions due to damage of canonical resting-state large-scale networks or changes in the composition of the entire brain. We also review emerging methods, such as lesion-network mapping and gradient analysis, used to study the aforementioned events caused by stroke lesions. Lastly, we examine other patient vulnerabilities, such as superimposed amyloid pathology and blood-brain barrier leakage, which potentially lead to different outcomes for the brain network compositions even in the presence of similar stroke lesions. This knowledge will allow a better understanding of the pathophysiology of post-stroke cognitive impairment and provide a theoretical basis for the development of new treatments, such as neuromodulation.

A Critical Review of Alien Limb-Related Phenomena and Implications for Functional Magnetic Resonance Imaging Studies

Consensus criteria on corticobasal degeneration (CBD) include alien limb (AL) phenomena. However, the gist of the behavioral features of AL is still “a matter of debate.” CBD-related AL has so far included the description of involuntary movements, frontal release phenomena (frontal AL), or asomatognosia (posterior or “real” AL). In this context, the most frequent symptoms are language and praxis deficits and cortical sensory misperception. However, asomatognosia requires, by definition, intact perception and cognition. Thus, to make a proper diagnosis of AL in the context of CBD, cognitive and language dysfunctions must be carefully verified and objectively assessed. We reviewed the current literature on AL in CBD and now propose that the generic use of the term AL should be avoided. This catchall AL term should instead be deconstructed. We propose that the term AL is appropriate to describe clinical features associated with specific brain lesions. More discrete sets of regionally bound clinical signs that depend on dysfunctions of specific brain areas need to be assessed and presented when posing the diagnosis. Thus, in our opinion, the AL term should be employed in association with precise descriptions of the accompanying involuntary movements, sensory misperceptions, agnosia-asomatognosia contents, and the presence of utilization behavior. The review also offers an overview of functional magnetic resonance imaging-based studies evaluating AL-related phenomena. In addition, we provide a complementary set of video clips depicting CBD-related involuntary movements that should not mistakenly be interpreted as signs of AL.

Acute Hemiballismus as the Initial Manifestation of Ischemic Stroke: A Case Report

Introduction

Cerebrovascular disease often presents with “negative” symptoms such as weakness with reduced movement of body parts or sensory loss. Rarely do “positive” symptoms such as abnormal movements manifest in acute stroke, with hemichorea being a very rare manifestation.

Case Report

This is a case report of a 62-year-old chronic smoker with no known past medical history who presented with choreatic movements of his arm and leg. Magnetic resonance imaging of the brain showed changes consistent with an infarct in the right centrum semiovale. He was treated with dual antiplatelets and was noted to have subsequent improvement in symptoms.

Conclusion

Recognition and awareness of stroke presenting as movement disorders in the emergency department can help prevent delays in diagnosis and treatment.

Neural mechanisms of foreign accent syndrome: Lesion and network analysis

BACKGROUND

Foreign accent syndrome (FAS) is a rare acquired speech disorder wherein an individual's spoken accent is perceived as "foreign." Most reported cases involve left frontal brain lesions, but it is known that various other lesions can also cause FAS. To determine whether heterogeneous FAS-causing lesions are localized to a common functional speech network rather than to a single anatomical site, we employed a recently validated image analysis technique known as "lesion network mapping."

METHODS

We identified 25 published cases of acquired neurogenic FAS without aphasia, and mapped each lesion volume onto a reference brain. We next identified the network of brain regions functionally connected to each FAS lesion using a connectome dataset from normative participants. Network maps were then overlapped to identify common network sites across the lesions.

RESULTS

Classical lesion overlap analysis showed heterogeneity in lesion anatomical location, consistent with prior reports. However, at least 80% of lesions showed network overlap in the bilateral lower and middle portions of the precentral gyrus and in the medial frontal cortex. The left lower portion of the precentral gyrus is suggested to be the location of lesions causing apraxia of speech (AOS), and the middle portion is considered to be a larynx-specific motor area associated with the production of vowels and stop/nasal consonants and with the determination of pitch accent.

CONCLUSIONS

The lesions that cause FAS are anatomically heterogeneous, but they share a common functional network located in the bilateral posterior region of the frontal lobe. This network specifically includes not only the lower portion of the central gyrus, but also its middle region, which is referred to as the larynx motor cortex and is known to be associated with phonation. Our findings suggest that disrupted networks in FAS might be anatomically different from those in AOS.

Pathological laughter and crying: insights from lesion network-symptom-mapping

The study of pathological laughter and crying (PLC) allows insights into the neural basis of laughter and crying, two hallmarks of human nature. PLC is defined by brief, intense and frequent episodes of uncontrollable laughter or crying provoked by trivial stimuli. It occurs secondary to CNS disorders such as stroke, tumours or neurodegenerative diseases. Based on case studies reporting various lesions locations, PLC has been conceptualized as dysfunction in a cortico-limbic-subcortico-thalamo-ponto-cerebellar network. To test whether the heterogeneous lesion locations are indeed linked in a common network, we applied 'lesion network-symptom-mapping' (LNSM) to 70 focal lesions identified in a systematic literature search for case reports of PLC. In LNSM normative connectome data (resting state functional MRI, n = 100) is used to identify the brain regions which are likely affected by diaschisis based on the lesion locations. With LNSM we were able to identify a common network specific for PLC when compared with a control cohort (n = 270). This bilateral network is characterized by positive connectivity to the cingulate and temporomesial cortices, striatum, hypothalamus, mesencephalon and pons and negative connectivity to the primary motor and sensory cortices. In the most influential pathophysiological model of PLC, a center for the control and coordination of facial expressions, respiration and vocalization in the periaqueductal grey is assumed which is controlled via two pathways: an emotional system that exerts excitatory control of the periaqueductal grey descending from the temporal and frontal lobes, basal ganglia and hypothalamus and a volitional system descending from the lateral premotor cortices which can suppress laughter or crying. To test whether the positive and negative PLC subnetworks identified in our analyses can indeed be related to an emotional system and a volitional system, we identified lesions causing emotional (n = 15) or volitional facial paresis (n = 46) in a second literature search. Patients with emotional facial paresis show preserved volitional movements but cannot trigger emotional movements in the affected hemiface, while the reverse is true for volitional facial paresis. Importantly, these lesions map differentially onto the PLC subnetworks: the 'positive PLC subnetwork' is part of the emotional system and the 'negative PLC subnetwork' overlaps with the volitional system for the control of facial movements. Based on this network analysis we propose a two-hit model of PLC: a combination of direct lesion and indirect diaschisis effects cause PLC through the loss of inhibitory cortical control of a dysfunctional emotional system.

Haemiballism/haemichorea: an atypical presentation of ischaemic stroke

A 76-year-old man was admitted to the hospital with acute onset of involuntary movements of the left side of his body. His neurological examination revealed he was oriented only to himself, and aforementioned movements of his left arm and leg. CT head demonstrated old infarcts in his right aspect of his pons and basal ganglia. Cerebrospinal fluid analysis was unremarkable. He initially had a normal blood glucose with an elevated anion gap and elevated creatine kinase. Brain MRI showed a small lacunar-type ischaemic infarct within the anteromedial aspect of the right cerebral peduncle, which localised to his haemiballism. To prevent worsening rhabdomyolysis associated with his haemiballism, the primary team initiated both tetrabenazine and diazepam. His movements improved after 1 week of medication therapy. This report discusses a thorough workup for this movement disorder and when to intervene for this distressing condition.

Acute chorea: case series from the emergency room of a Brazilian tertiary-level center

BACKGROUND

Chorea is a movement disorder characterized by random, brief and migratory involuntary muscle contractions. It is defined as acute when present within hours to days. Three main causes for this scenario have emerged as most likely: vascular, toxic-metabolic and inflammatory.

OBJECTIVES

To identify the prevalence of the main etiologies and major clinical findings of acute chorea in the emergency room of a tertiary-level referral center; and to suggest an approach for guiding the diagnostic workup and clinical management.

METHODS

We retrospectively reviewed the clinical aspects and neuroimaging data of 10 patients presenting with acute chorea at the neurological emergency room of our hospital from 2015 to 2019.

RESULTS

Stroke was the most common etiology (50% of the cases). All of them were ischemic. It was noteworthy that only one case demonstrated the classical ischemic topographic lesion at the contralateral subthalamic nuclei. Regarding nonvascular etiologies, nonketotic hyperglycemia was the major cause, followed by drug-related chorea. One patient showed inflammatory etiology, which was probably Sydenham chorea reactivation.

CONCLUSION

Acute chorea is an uncommon and challenging problem at the emergency room, often associated with potentially treatable causes. We suggest that use of the acronym DANCE (Diagnosis of chorea, Acute stroke protocol, Normal glucose levels, Check neuroimaging, Exposure to drugs) could form a potential initial approach in the evaluation, in order to emphasize causes that require prompt proper management (e.g. thrombolysis).

Lesion-based structural and functional networks in patients with step length asymmetry after stroke

OBJECTIVE

The aim of this study was to determine common structural and functional networks associated with asymmetric step length after unilateral ischemic stroke.

METHODS

Thirty-nine chronic stroke patients were divided into two groups, based on the presence or absence of asymmetric step length. In each group, each lesion was mapped onto a brain magnetic resonance image. The structural and functional networks of brain regions connected to each lesion were identified using a public diffusion tensor and resting state function magnetic resonance image dataset. To identify brain regions associated with asymmetric step length, we conducted voxel-wise independent sample t-tests for structural and function lesion network maps.

RESULTS

At least 85% of lesions showed functional network overlap in the bilateral frontal lobe. Functional connectivity of the dorsolateral prefrontal cortex in the contralesional hemisphere was significantly decreased in group 1 compared to that in group 2.

CONCLUSIONS

The dorsolateral prefrontal cortex may have an important role in compensating for an asymmetric step length after a unilateral stroke.

Sydenham Chorea: Putaminal Enlargement

BACKGROUND

Our aim in this study was to evaluate the efficacy of magnetic resonance imaging (MRI) studies in the detection of brain regions effected by Sydenham chorea and to determine whether they provided data regarding the pathogenesis of Sydenham chorea. To this end, we assessed basal ganglia structures in Sydenham chorea patients and control group by quantitative MRI volumetric analysis.

METHODS

Patients with a recent onset of chorea and control subjects matched for age and gender were included in the study. Medical history, laboratory tests, and physical and neurologic examinations were reviewed. All MRIs were considered within normal limits. High-resolution T1-weighted 3D magnetization-prepared rapid acquisition of gradient echo scans were used for quantitative volumetric assessment of the brain via the "volBrain" method.

RESULTS

Twenty-four subjects with Sydenham chorea (16 girls and 8 boys, aged between 7 and 16 years) and 35 control subjects were evaluated. Mean age was 11.25 ± 2.89 years for Sydenham chorea patients and 10.58 ± 2.53 years for the controls. No significant difference was found relative to globus pallidus, caudate, and thalamic volumes between patients with Sydenham chorea and controls. The relative mean total, left, and right putamen volumes were significantly larger in patients with Sydenham chorea compared to controls (P = .003, P = .018, P = .001, respectively).

CONCLUSION

Selective neuroanatomic differences in putamen among other basal ganglia structures and significant increases in size are consistent with a hypothesis of a cross-reactive antibody-mediated inflammation of the putamen as being the pathophysiologic mechanism for this disorder.