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Axial FLAIR image (A) demonstrates left dentate nucleus hyperintensity and axial T2 image (B) shows hyperintensity in the right inferior olivary nucleus.
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Objective:
The learning objectives of this review include recognition of the imaging characteristics of transaxonal degenerations involving cerebellar connections, the identification of potential encephalic lesions that can lead to these degenerations and correlation of the clinical manifestations with imaging findings that reflect this involvement...
Context in source publication
Context 1
... 59-year-old male patient with HIV infection for 20 years presented with a paracoccidioidomycosis infection of the central nervous system (CNS) in the early years of HIV infection. Routine MRI of the brain showed a lesion in the left dentate nucleus and consequent contralateral HOD (Figure 3) caused by interruption of the dentate-rubro-olivary pathway (Guillain-Mollaret triangle) 10,11 . Clinically, the patient showed movement disorder characterized by hyperkinesia 12 . ...
Citations
... HOD is caused by injury to the dentato-rubro-olivary circuit, also known as the Guillain-Mollaret triangle. 2 Efferent fibers originating in the dentate nucleus project through the superior cerebellar peduncle to the contralateral red nucleus. Red nucleus fibers project to the ipsilateral ION via the central tegmental tract (CTT). ...
... This pattern of significant WM involvement is also present at the level of the infratentorial compartment, affecting mainly the cerebellar WM [71,76,77] and the middle cerebellar peduncles (MCP) [78], while signal changes at the level of midbrain and pons are less frequently reported [79,80]. Additional signal changes reported in these patients are the presence of T2 WI-hyperintense lesions at the level of the dorso-medial thalami [71,81] and the basal ganglia [68,74,82], as well as bilateral hypertrophic olivary hyperintensities, which should be differentiated from hypertrophic olivary degeneration (HOD) [69,70,81,[83][84][85][86], especially in phenotypes with progressive ataxia and palatal tremor (PAPT) syndrome [70]. Atrophy or signal changes in DN [83] have also been reported, often in patients with bilateral lesions of the inferior olives [87,88], while in AHS patients, a severe cerebral atrophy and delayed myelination, along with BG lesions, have also been described [89]. ...
The association of cerebellar ataxia and hypogonadism occurs in a heterogeneous group of disorders, caused by different genetic mutations often associated with a recessive inheritance. In these patients, magnetic resonance imaging (MRI) plays a pivotal role in the diagnostic workflow, with a variable involvement of the cerebellar cortex, alone or in combination with other brain structures. Neuroimaging involvement of the pituitary gland is also variable. Here, we provide an overview of the main clinical and conventional brain and pituitary gland MRI imaging findings of the most common genetic mutations associated with the clinical phenotype of ataxia and hypogonadism, with the aim of helping neuroradiologists in the identification of these disorders.
... The main differential diagnosis of PAPT is hypertrophic olivary degeneration, in which the pathology of the palatal tremor is disruption of the Guillain-Mollaret triangle (21,22) . ...
Ataxia is defined as a lack of coordination of voluntary movement, caused by a variety of factors. Ataxia can be classified by the age at onset and type (chronic or acute). The causative lesions involve the cerebellum and cerebellar connections. The correct, appropriate use of neuroimaging, particularly magnetic resonance imaging, can make the diagnosis relatively straightforward and facilitate implementation of the appropriate clinical management. The purpose of this pictorial essay is to describe the imaging findings of ataxia, based on cases obtained from the archives of a tertiary care hospital, with a review of the most important findings. We also discuss and review the imaging aspects of neoplastic diseases, malformations, degenerative diseases, and hereditary diseases related to ataxia.
... Furthermore, lesions in the dentate nucleus may determine hypertrophic olivary degeneration and other transaxonal degenerations. 2 This article reviews several possible causes of dentate nucleus lesions based on the neuroimaging studies recovered from the archives of our institution. ...
The dentate nucleus is the largest cerebellar nucleus, and it controls cognition and voluntary movement. It is found in each cerebellar hemisphere medially and posterolateral to the lateral ventricle. Pathologies of the dentate nucleus can be detected using computed tomography and magnetic resonance imaging of the brain. Here, we present a case series of seven different dentate nucleus diseases and their neuroimaging findings recovered from archives of our institution.
... We did not expand here on the numerous MRI reports describing the location of lesions in the G-M triangle and the involvement of the central tegmental tract, the dentatorubrothalamic tract, the transaxonal degeneration, and Wallerian degeneration [see the recent work of Raeder et al. (94) focusing on imaging characteristics of transaxonal degenerations involving cerebellar connections]. ...
Lesions in the Guillain–Mollaret (G–M) triangle frequently cause various types of tremors or tremor-like movements. Nevertheless, we know relatively little about their generation mechanisms. The deep cerebellar nuclei (DCN), which is a primary node of the triangle, has two main output paths: the primary excitatory path to the thalamus, the red nucleus (RN), and other brain stem nuclei, and the secondary inhibitory path to the inferior olive (IO). The inhibitory path contributes to the dentato-olivo-cerebellar loop (the short loop), while the excitatory path contributes to the cerebrocerebellar loop (the long loop). We propose a novel hypothesis: each loop contributes to physiologically distinct type of tremors or tremor-like movements. One type of irregular tremor-like movement is caused by a lesion in the cerebrocerebellar loop, which includes the primary path. A lesion in this loop affects the cerebellar forward model and deteriorates its accuracy of prediction and compensation of the feedback delay, resulting in irregular instability of voluntary motor control, i.e., cerebellar ataxia (CA). Therefore, this type of tremor, such as kinetic tremor, is usually associated with other symptoms of CA such as dysmetria. We call this type of tremor forward model-related tremor. The second type of regular tremor appears to be correlated with synchronized oscillation of IO neurons due, at least in animal models, to reduced degrees of freedom in IO activities. The regular burst activity of IO neurons is precisely transmitted along the cerebellocerebral path to the motor cortex before inducing rhythmical reciprocal activities of agonists and antagonists, i.e., tremor. We call this type of tremor IO-oscillation-related tremor. Although this type of regular tremor does not necessarily accompany ataxia, the aberrant IO activities (i.e., aberrant CS activities) may induce secondary maladaptation of cerebellar forward models through aberrant patterns of long-term depression (LTD) and/or long-term potentiation (LTP) of the cerebellar circuitry. Although our hypothesis does not cover all tremors or tremor-like movement disorders, our approach integrates the latest theories of cerebellar physiology and provides explanations how various lesions in or around the G–M triangle results in tremors or tremor-like movements. We propose that tremor results from errors in predictions carried out by the cerebellar circuitry.
Lesions in the Guillain-Mollaret (G-M) triangle frequently cause various types of tremors. Nevertheless, we know relatively little about their mechanisms. The deep cerebellar nuclei, representing a primary node of the triangle, have two distinct output paths: the primary glutamatergic excitatory path to the thalamus, the red nucleus, and other brain stem nuclei, and the secondary GABAergic inhibitory path to the inferior olive (IO). The excitatory path contributes to the cerebrocerebellar loop (the long loop), while the inhibitory path contributes to the cerebello-olivo-cerebellar loop (the short loop). We propose a novel hypothesis: each loop contributes to a pathophysiologically distinct type of tremors. A lesion in the cerebrocerebellar loop causes an irregular tremor. A lesion in this loop affects the cerebellar forward model. It deteriorates its accuracy of prediction and compensation of the sensory feedback delay, resulting in irregular instability of voluntary motor control. Therefore, this type of tremors, such as intention tremor or kinetic tremor, is usually associated with other symptoms of cerebellar ataxia, such as dysmetria. We call this type of tremor forward-model-related tremor. The second type of regular tremor appears to originate from the synchronized oscillation of IO cells due, at least in animal models, to reduced degrees of freedom in IO activities. The regular burst activity of IO cells is precisely transmitted along the olivo-cerebello-cerebral path to the motor cortex before inducing bursts of activities of agonist and antagonist muscles. We call this type of tremor IO-oscillation-related tremor. Although these types of regular tremors, such as essential tremor or rest tremor, do not necessarily accompany ataxia, the aberrant IO activities (i.e., aberrant complex spike, CS, activities) may induce moderate maladaptation of cerebellar forward models by reducing degrees of freedom in fundamental mechanisms of plasticity such as long-term depression (LTD) and long-term potentiation (LTP) of the cerebellar circuitry. Our hypothesis explains how lesions in or around the G-M triangle result in mixtures of two types of tremors, resulting in a complex phenotypic presentation.
Background Sjogren-Larsson syndrome (SLS) is a neurocutaneous disease with an autosomal recessive inheritance, caused by mutations in the gene that encodes fatty aldehyde dehydrogenase ( ALDH3A2 ), clinically characterized by ichthyosis, spastic diplegia, and cognitive impairment. Brain imaging plays an essential role in the diagnosis, demonstrating a nonspecific leukoencephalopathy. Data regarding brain atrophy and grey matter involvement is scarce and discordant.
Objective We performed a volumetric analysis of the brain of two siblings with SLS with the aim of detecting deep grey matter nuclei, cerebellar grey matter, and brainstem volume reduction in these patients.
Methods Volume data obtained from the brain magnetic resonance imaging (MRI) of the two patients using an automated segmentation software (Freesurfer) was compared with the volumes of a healthy control group.
Results Statistically significant volume reduction was found in the cerebellum cortex, the brainstem, the thalamus, and the pallidum nuclei.
Conclusion Volume reduction in grey matter leads to the hypothesis that SLS is not a pure leukoencephalopathy. Grey matter structures affected in the present study suggest a dysfunction more prominent in the thalamic motor pathways.
La degeneración olivar hipertrófica, es una enfermedad secundaria al daño en el circuito neuronal del Triángulo de Guillain Mollaret, generando síntomas tan variados como el temblor de Holmes. El presente artículo describe el caso de un hombre de 52 años, con antecedente de trauma craneoencefálico en 2016, sin secuelas mediatas, quien de manera progresiva presenta temblor, asociándose 5 años después a cefalea requiriendo asistencia a urgencias, allí realizan estudios e instauran terapia farmacológica. Finalmente se concluye, que lesiones postraumáticas en el Triángulo de Guillain Mollaret, pueden generar como secuelas trastornos del movimiento secundarios a degeneración olivar hipertrófica, una entidad poco diagnosticada.
Tuberous Sclerosis is a genetic multisystemic disease that mainly affects the central nervous system (CNS) of patients at any age. This study illustrates the neuroimaging findings that are included in the clinical diagnostic criteria in a group of patients with tuberous sclerosis (TS) of two tertiary university hospitals. The neuroimaging findings, in order of frequency, are cortical tubers, subependymal nodules, white matter abnormalities and subependymal giant cells astrocytomas. All these lesions represent disorganized neurons and glial cells. Cerebellar and hippocampal abnormalities have also been described in TS. Neuroimaging, particularly magnetic resonance imaging (MRI), has a crucial role in the evaluation and diagnosis of tuberous sclerosis, especially in atypical clinical presentations or in cases of inadequate therapeutic response.
