SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Alien hand syndrome

168

Patients with alien hand syndrome (AHS) experience making apparently deliberate and purposeful movements with their hand against their will. However, the mechanisms contributing to these involuntary actions remain poorly understood. Here, we describe two experimental investigations in a patient with corticobasal syndrome (CBS) with alien hand behaviour in her right hand. First, we show that responses with the alien hand are made significantly more quickly to images of objects which afford an action with that hand compared to objects which afford an action with the unaffected hand. This finding suggests that involuntary grasping behaviours in AHS might be due to exaggerated, automatic motor activation evoked by objects which afford actions with that limb. Second, using a backwards masked priming task, we found normal automatic inhibition of primed responses in the patient’s unaffected hand, but importantly there was no evidence of such suppression in the alien limb. Taken together, these findings suggest that grasping behaviours in AHS may result from exaggerated object affordance effects, which might potentially arise from disrupted inhibition of automatically evoked responses.

Concepts: Patient, Corpus callosum, Alien hand syndrome

28

We report a patient who presented with callosal disconnection syndrome (CDS) and fiber disconnection on diffusion tensor tractography (DTT) after an infarct of the corpus callosum (CC). A 72-year-old woman presented with manifestations of CDS, including frontal alien hand syndrome (AHS), left agraphia, right hemiparesis, right somatosensory deficit, left neglect, and impaired visual recognition. DTT was performed for the evaluation of CC fibers, followed by comparison with DTT findings of normal subjects. DTT of the normal subject revealed bilateral extension of CC fibers to the frontal, parietal, and occipitotemporal cortices. By contrast, CC fibers of the patient revealed extensive disruption, with the exception of CC fibers passing through the anterior genu and the posterior splenium. The extensive disruption of CC fibers appears to explain the patient’s various CDS symptoms. In brief, DTT could be useful for detection of CC lesions in patients with CDS.

Concepts: Patient, Cerebrum, Corpus callosum, Splenium, Neurological disorders, Agenesis of the corpus callosum, Alien hand syndrome, Genu of the corpus callosum

0

Congenital neurological disorders are genetically highly heterogeneous. Rare forms of hereditary neurological disorders are still difficult to be adequately diagnosed. Pertinent studies, especially when reporting only single families, need independent confirmation. We present three unrelated families in which whole-exome sequencing identified the homozygous non-sense variants c.430[C>T];[C>T] p.(Arg144*), c.1219[C>T];[C>T] p.(Gln407*) and c.1408[C>T];[C>T] p.(Arg470*) in GTPBP2. Their clinical presentations include early onset and apparently non-progressive motor and cognitive impairment, and thereby overlap with findings in a recently described family harbouring a homozygous GTPBP2 splice site variant. Notable differences include structural brain abnormalities (e.g., agenesis of the corpus callosum, exclusive to our patients), and evidence for brain iron accumulation (exclusive to the previously described family). This report confirms pathogenicity of biallelic GTPBP2 inactivation and broadens the phenotypic spectrum. It also underlines that a potential involvement of brain iron accumulation needs clarification. Further patients will have to be identified and characterised in order to fully define the core features of GTPBP2-associated neurological disorder, but future approaches to molecular diagnosis of neurodevelopmental disorders should implement GTPBP2.

Concepts: Psychology, Neurology, Autism, Corpus callosum, Neurological disorder, Neurological disorders, Neurodevelopmental disorder, Alien hand syndrome

0

Alien limb phenomenon occurs in 50-60% of patients with corticobasal syndrome (CBS) and usually presents with an “alien hand” phenomenon. The “alien foot” presentation is rarer and may be misdiagnosed, as foot involvement can lead to erroneous localization of the clinical problem to the knee, hip, or back. Subsequently misdiagnoses such as myelopathy, radiculopathy, functional disorder, stiff leg syndrome, neuromyotonia, and painful leg moving toes syndrome may occur.

Concepts: Foot, Human leg, Neurological disorders, Alien hand syndrome, The Wolf in Sheep's Clothing

0

The alien hand syndrome (AHS) is a rare neuropsychological disorder characterized by involuntary, yet purposeful, hand movements. Patients with the AHS typically complain about a loss of agency associated with a feeling of estrangement for actions performed by the affected limb. The present study explores the integrity of the body representation in AHS, focusing on 2 main processes: multisensory integration and visual self-recognition of body parts. Three patients affected by AHS following a right-hemisphere stroke, with clinical symptoms akin to the posterior variant of AHS, were tested and their performance was compared with that of 18 age-matched healthy controls.

Concepts: Present, Symptom, Corpus callosum, Performance, Clinical neuropsychology, Alien hand syndrome, The Alien

0

Alien hand syndrome (AHS) is characterized by involuntary and autonomous activity of the affected limbs, and consists of the frontal, callosal and posterior AHS variants. The callosal subtype, resulting from damage to the corpus callosum, frequently features intermanual conflict. However, infarction of the corpus callosum is rare due to abundant blood supply. The present study reported a case of AHS (callosal subtype, in the right hand) caused by callosal infarction. Infarction of the left corpus callosum was confirmed with magnetic resonance imaging. In addition, magnetic resonance angiography and digital subtraction angiography examinations revealed multiple lesions in the feeding arteries. Subsequent to antiplatelet therapy for 2 weeks following admission, the patient gradually recovered. Furthermore, the current study reviewed 31 previously reported cases of AHS following callosal infarction in the literature.

Concepts: Medical imaging, Magnetic resonance imaging, Angiography, Radiology, Corpus callosum, Digital subtraction angiography, Intravenous digital subtraction angiography, Alien hand syndrome

0

Alien hand syndrome (AHS) is an involuntary and rare neurological disorder emerges at upper extremity. AHS is a disconnection syndrome with the symptoms of losing sense of agency and sense of ownership, and presence of involuntary autonomic motor activity. There are frontal, callosal and posterior types of AHS and each of them occurs depend on the lesions of different of the brain. Posterior variant is a rarely encountered AHS type compared to others. AHS, generally regarded as persistent, but rarely maybe observed as paroxysmal. In this article, we present 71 year old patient with right posterior parietal lobe infarction and developed posterior variant AHS on left arm 1 month after discharge from the hospital. To discriminate AHS from conditions such as extrapyramidal movement disorders and epileptic seizures that take part in differential diagnosis should be kept in mind by the clinicians. Wrong and unnecessary treatments could be prevented in this way.

Concepts: Neurology, Cerebrum, Epilepsy, Frontal lobe, Parietal lobe, Neurological disorder, Posterior parietal cortex, Alien hand syndrome

0

Alien hand syndrome (AHS) is a rare disorder of involuntary limb movement together with a sense of loss of limb ownership. It most commonly affects the hand, but can occur in the leg. The anterior (frontal, callosal) and posterior variants are recognized, with distinguishing clinical features and anatomical lesions. Initial descriptions were attributed to stroke and neurosurgical operations, but neurodegenerative causes are now recognized as most common. Structural and functional imaging and clinical studies have implicated the supplementary motor area, pre-supplementary motor area, and their network connections in the frontal variant of AHS, and the inferior parietal lobule and connections in the posterior variant. Several theories are proposed to explain the pathophysiology. Herein, we review the literature to update advances in the understanding of the classification, pathophysiology, etiology, and treatment of AHS.

Concepts: Medicine, The Canon of Medicine, Avicenna, Cerebrum, Corpus callosum, Anatomy, Explanation, Alien hand syndrome

0

Copy Number Variations (CNVs) comprising the distal 1q region 1q43-q44 are associated with neurological impairments, structural brain disorder, and intellectual disability. Here, we report an extremely rare, de novo case of a 1q43-q44 deletion with an adjacent duplication, associated with severe seizures, microcephaly, agenesis of the corpus callosum, and pachygyria, a consequence of defective neuronal migration disorder. We conducted a literature survey to find that our patient is only the second case of such a 1q43-q44 CNV ever to be described. Our data support an association between 1q43-q44 deletions and microcephaly, as well as an association between 1q43-q44 duplications and macrocephaly. We compare and contrast our findings with previous studies reporting on critical 1q43-q44 regions and their constituent genes associated with seizures, microcephaly, and corpus callosum abnormalities [Ballif et al., 2012; Hum Genet 131:145-156; Nagamani et al., 2012; Eur J Hum Genet 20:176-179]. Taken together, our study reinforces the association between 1q43-q44 CNVs and brain disorder. © 2016 Wiley Periodicals, Inc.

Concepts: Nervous system, DNA, Copy number variation, Neurology, Cerebrum, Corpus callosum, Agenesis of the corpus callosum, Alien hand syndrome

0

The corpus callosum connects the two cortical hemispheres of the mammalian brain and is susceptible to structural defects during development, which often result in significant neuropsychological dysfunction. To date, such individuals have been studied primarily with regards to the integrity of the callosal tract at the midline. However, the mechanisms regulating the contralateral targeting of the corpus callosum, after midline crossing has occurred, are less well understood. Recent evidence suggests that defects in contralateral targeting can occur in isolation from midline-tract malformations, and may have significant functional implications. We propose that contralateral targeting is a crucially important and relatively under-investigated event in callosal development, and that defects in this process may constitute an undiagnosed phenotype in several neurological disorders.

Concepts: Psychology, Neurology, Cerebrum, Corpus callosum, Marsupial, Agenesis of the corpus callosum, Monotreme, Alien hand syndrome