Transaxonal degenerations of cerebellar connections: the value of anatomical knowledge

Raeder, Mariana Trombetta de Lima; Reis, Eduardo Pontes; Campos, Brunno M.; Zamilute, Igor Aloísio Garcez; Júnior, Marcondes Cavalcante França; Reis, Fabiano

doi:10.1590/0004-282x20200021

Cited by 8 publications

(5 citation statements)

References 26 publications

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“…Targeted thalamotomies and deep brain stimulation have been successfully used to treat involuntary movements, confirming its essential role in motor functions. There are cerebellum-recipient thalamus nuclei 27 and basal ganglia-recipient (pallidum and substantia nigra) thalamus nuclei, with afferent pathways to the frontal cortex. 28 Coincidentally, the structures involved in these pathways are the structures with significant volume reduction in the present study (that is, the cerebellum, the thalamus, and the pallidum).…”

Section: Discussionmentioning

confidence: 99%

Sjogren-Larsson syndrome brain volumetric reductions demonstrated with an automated software

Castro,

Saab,

Souto

et al. 2023

Arq Neuropsiquiatr

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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.

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Section: Discussionmentioning

confidence: 99%

Sjogren-Larsson syndrome brain volumetric reductions demonstrated with an automated software

Castro,

Saab,

Souto

et al. 2023

Arq Neuropsiquiatr

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“…The disorder is also associated with cerebellar and brainstem atrophy ( Figure 6 ). 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 ) .…”

Section: Degenerative Diseasesmentioning

confidence: 99%

“…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) .…”

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confidence: 99%

Common and uncommon neuroimaging manifestations of ataxia: an illustrated guide for the trainee radiologist. Part 2 - neoplastic, congenital, degenerative, and hereditary diseases

et al. 2022

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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.

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“…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].…”

Section: Section II Physiological Backgrounds Of Two Types Of Cerebellar Tremorsmentioning

confidence: 99%

Pathophysiology of Cerebellar Tremor: The Forward Model-Related Tremor and the Inferior Olive Oscillation-Related Tremor

et al. 2021

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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.

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Transaxonal degenerations of cerebellar connections: the value of anatomical knowledge

Cited by 8 publications

References 26 publications

Sjogren-Larsson syndrome brain volumetric reductions demonstrated with an automated software

Sjogren-Larsson syndrome brain volumetric reductions demonstrated with an automated software

Common and uncommon neuroimaging manifestations of ataxia: an illustrated guide for the trainee radiologist. Part 2 - neoplastic, congenital, degenerative, and hereditary diseases

Pathophysiology of Cerebellar Tremor: The Forward Model-Related Tremor and the Inferior Olive Oscillation-Related Tremor

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