Transaxonal degenerations of cerebellar connections: the value of anatomical knowledge / Degenerações transaxonais das conexões cerebelares: o valor do conhecimento anatômico

ABSTRACT Transaxonal degenerations result from neuronal death or the interruption of synaptic connections among neuronal structures. These degenerations are not common but may be recognized by conventional magnetic resonance imaging. 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. Methods: In this report, we review the neuroanatomical knowledge that provides a basis for identifying potential lesions that can result in these degenerations involving cerebellar structures. Results: Hypertrophic olivary degeneration results from an injury that interrupts any of the components of the Guillain-Mollaret triangle. In this work, we describe cases of lesions in the dentate nucleus and central tegmental tract. The crossed cerebellar diaschisis presents specific imaging findings and clinical correlations associated with its acute and chronic phases. The Wallerian degeneration of the middle cerebellar peduncle is illustrated by fiber injury of the pontine cerebellar tracts. A T2-hyperintensity in the dentate nucleus due to a thalamic acute lesion (in ventral lateral nuclei) is also described. Each condition described here is documented by MRI images and is accompanied by teaching points and an anatomical review of the pathways involved. Conclusion: Neurologists and radiologists need to become familiar with the diagnosis of these conditions since their presentations are peculiar and often subtle, and can easily be misdiagnosed as ischemic events, degenerative disease, demyelinating disease or even tumors.

RESUMO Degenerações transaxonais resultam da morte neuronal ou da interrupção de conexões sinápticas entre estruturas neurais. Essas degenerações não são comuns, mas podem ser reconhecidas por imagens de ressonância magnética convencional. Objetivo: Os objetivos de aprendizado desta revisão incluem o reconhecimento das características de imagem de degenerações transaxonais envolvendo conexões cerebelares, a identificação de possíveis lesões encefálicas que podem levar a essas degenerações e a correlação das manifestações clínicas com os achados de imagem que refletem esse envolvimento. Métodos: Neste artigo, revisamos conhecimentos neuroanatômicos que fornecem a base para identificar possíveis lesões que podem resultar nessas degenerações envolvendo estruturas cerebelares. Resultados: A degeneração olivar hipertrófica resulta de uma lesão que interrompe algum dos componentes do triângulo de Guillain-Mollaret. Neste trabalho, descrevemos casos de lesões no núcleo denteado e no trato tegmentar central. A diásquise cerebelar cruzada apresenta achados de imagem específicos e correlações clínicas associadas às suas fases aguda e crônica. A degeneração walleriana dos pedúnculos cerebelares médios é ilustrada pela lesão dos tratos pontino-cerebelares. Uma hiperintensidade em T2 do núcleo denteado devido a uma lesão talâmica aguda (no núcleo ventrolateral) também é descrita. Cada condição aqui descrita é documentada por imagens de ressonância magnética e é acompanhada por pontos didáticos e uma revisão anatômica das vias envolvidas. Conclusão: Neurologistas e radiologistas precisam estar familiarizados com o diagnóstico dessas condições, uma vez que suas apresentações são peculiares e frequentemente sutis, e podem ser facilmente equivocadamente diagnosticadas como lesões isquêmicas, doenças degenerativas, desmielinizantes, ou mesmo tumorais.

A case of unilateral hypertrophic olivary degeneration following bilateral medial medullary infarction / 中华神经科杂志

Bilateral medial medullary infarction is a rare type of stroke. Hypertrophic olivary degeneration (HOD) is usually secondary to the lesion involving the Guillain-Mollaret triangle with vacuolar degeneration of inferior olivary nucleus neurons and enlargement of inferior olivary nucleus. The primary lesions involving the Guillain-Mollaret triangle are usually located in midbrain, pons and cerebellum. A case of unilateral HOD secondary to bilateral medial medullary infarction is reported and the clinical characteristics, diagnosis and treatment are analyzed in order to improve the understanding of HOD.

Holmes' Tremor Associated with Bilateral Hypertrophic Olivary Degeneration Following Brain Stem Hemorrhage: A Case Report

Holmes' tremor is a condition characterized by a mixture of postural, rest, and action tremors due to midbrain lesions in the vicinity of the red nucleus. Hypertrophic olivary degeneration (HOD) is a rare type of neuronal degeneration involving the dento-rubro-olivary pathway and may present clinically as Holmes tremor. We report on a 59-year-old female patient who developed Holmes tremor in association with bilateral HOD, following brain stem hemorrhage.

A study of neuronal profile of inferior olivary nuclear complex in foetal and adult human medulla.

Introduction: ION receives proprioceptive impulses from spino-olivary tract and conveys the fibers to the cerebellum through olivo-cerebellar tract. There is paucity of data in human olivary complex, hence the present study is done. Materials and Methods: Study was conducted with 15 adult brains and 25 fetuses of different gestations were perfused with 10% formalin and processed for histological examination. Obeservations: Rounded cells have been seen infiltrating the entire field. at 16 weeks of gestation. Segregation of neurons into principal, medial, and dorsal accessory olivary nuclei at 20 wks gestation. Discussion: Neuron differentiation into oval, round, multipolar types has begun at 40 wks gestation. Neurons in the olivary subdivisions are grouped in separate clusters as per Ramon y Cajal,1909; Scheibel and Scheibel, 1955, Bowman and King, 1973. Multipolar neurons dominated in adult inferior olivary nucleus. Conclusion: The greater development of neurons is a consequence of finer regulation of various movements of hands and finger associated with movement of head and eyes.

Leber's Hereditary Optic Neuropathy with Olivocerebellar Degeneration due to G11778A and T3394C Mutations in the Mitochondrial DNA

BACKGROUND: Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder with optic nerve atrophy. Although there are no other associated neurological abnormalities in most cases of LHON, cases of "LHON plus" have been reported. CASE REPORT: The proband was a 37-year-old man who had visual and gait disturbances that had first appeared at 10 years of age. He showed horizontal gaze palsy, gaze-evoked nystagmus, dysarthria, and cerebellar ataxia. Brain and orbit MRI disclosed atrophy of the optic nerve and cerebellum, and degenerative changes in the bilateral inferior olivary nucleus. Mutational analyses of mitochondrial DNA identified the coexistence of heteroplasmic G11778A and homoplasmic T3394C mutations. CONCLUSIONS: These results suggest that the combination of G11778A and T3394C mutations leads to an atypical LHON phenotype.

Função do sistema olivococlear medial em crianças com desvio fonológico / Function of the medial olivocochlear system in children with phonological disorders

OBJETIVO: Verificar se crianças com desvio fonológico apresentam alterações do sistema olivococlear medial. MÉTODOS: Trata-se de estudo prospectivo e transversal. Foram avaliadas 19 crianças normo-ouvintes, de ambos os gêneros, com idades entre 4 e 7 anos, que foram divididas em dois grupos: 11 crianças sem desvio fonológico (grupo controle) e oito com desvio fonológico (grupo estudo). A condição auditiva foi verificada por meio da inspeção visual do meato acústico externo, audiometria tonal liminar e imitanciometria. Foram incluídas em ambos os grupos somente as crianças com limiares tonais iguais ou inferiores a 15 dB, timpanometria tipo A e reflexos acústicos presentes. Para avaliar a função do sistema olivococlear medial procedeu-se à avaliação das emissões otoacústicas evocadas transientes (EOAET) com e sem aplicação de ruído branco na intensidade de 60 dBNA contralateralmente. Os dados foram analisados estatisticamente. RESULTADOS: A ocorrência e a média dos valores de supressão das EOAET das orelhas direita e esquerda não apresentaram diferenças nas frequências de 1, 2, 3 e 4 kHz intragrupos estudo e controle. Na comparação da média e ocorrência do efeito supressor das emissões otoacústicas evocadas transientes entre grupo controle e grupo estudo, também não houve diferenças nas frequências analisadas. CONCLUSÃO: Crianças com desvio fonológico não apresentam alterações do sistema olivococlear medial, aspecto evidenciado pela ocorrência do efeito supressor das emissões otoacústicas evocadas transientes.

PURPOSE: To verify whether children with phonological disorders present alterations in the medial olivocochlear system. METHODS: This is a prospective cross-sectional study in which 19 normal hearing children of both genders, with ages between 4 and 7 years, were divided into two groups: 11 children without phonological disorders (control group) and eight with phonological disorders (study group). The auditory condition was verified by visual examination of the external ear canal, pure tone audiometry, and tympanometry. The study included only children with hearing thresholds below or equal to 15 dB, type A tympanometry, and presence of acoustic reflexes. To evaluate the function of the medial olivocochlear system, it was carried out the evaluation of transient evoked otoacoustic emissions (TEOAE) with and without contralateral white noise at 60 dBHL. Data were statistically analyzed. RESULTS: The occurrence and average values of TEOAE suppression in right and left ears did not present differences in the frequencies of 1, 2, 3 and 4 kHz within groups. In the comparison of the mean and the occurrence of the suppressive effect of TEOAE between control and study groups, there was also no difference in the frequencies analyzed. CONCLUSION: Children with phonological disorders do not present alterations in the medial olivocochlear system, as evidenced by the occurrence of the suppressive effect of transient evoked otoacoustic emissions.

3-Dimensional Analyses of Eye Motion in Oculopalatal Tremor

BACKGROUND: Oculopalatal tremor (OPT) is a delayed complication of damage to the dentato-rubro-olivary pathway (Guillain-Mollaret triangle) and subsequent hypertrophic olivary degeneration. Mixed torsional-vertical pendular nystagmus in OPT has been considered to signify unilateral brainstem damage while symmetrical vertical nystagmus has been regarded to indicate bilateral disease. However, 3-dimensional oculographic analysis of OPT has been sparse. METHODS: In 8 patients with OPT; binocular 3-dimensional analyses of ocular oscillations were performed by using a magnetic search coil technique. Lateralization of the lesions was determined by the imaged olivary hypertrophy in the MRI. RESULTS: One patient had conjugate vertical pendular nystagmus and four showed mixed torsional-vertical pendular nystagmus. Two patients showed mixed horizontal-torsional-vertical nystagmus. One patient had predominantly horizontal pendular nystagmus. MRI demonstrated increased signal or hypertrophy of the inferior olivary nucleus, unilateral in six and bilateral in two. Unilateral olivary changes were associated with mixed torsional-vertical nystagmus in three patients, mixed horizontal-torsional-vertical nystagmus in another two patients, and predominantly horizontal pendular nystagmus in the remaining one patient. Bilateral olivary changes were visible in one patient with conjugate vertical pendular nystagmus and in the other patient with mixed torsional-vertical nystagmus. Palatal tremor appeared to be symmetrical in all patients. CONCLUSIONS: Three-dimensional analyses of OPT indicate that conjugate vertical and mixed torsional-vertical pendular nystagmus do not correspond to the laterality of signal changes in the inferior olivary nucleus. Ocular oscillations often have all the vertical, horizontal and torsional components.

A Case of Dystonic Tremor with Left Hemiparesis in Cervicomedullary Infarction

The development of involuntary movement by the lesion in the brainstem and spinal cord has been rarely reported. We report a 56-year-old man who suffered from bilateral dystonic tremor and left hemiparesis by an acute cervicomedullary infarction. The patient had acute infarcted lesion on the anterior-medial cervicomedullary junction located at the inferior olivary nucleus. Current study suggests that the involvement of inferior olivary nucleus in lower medulla could be a cause to develop dystonic tremor by cervicomedullary lesions.

Spatio-temporal Changes on c-Fos Protein Expression in the Brain Stem Nuclei following Arsanilate-induced Unilateral Labyrinthectomy in Rats

Spatio-temporal changes on c-Fos protein expression were investigated in vestibular compensation following unilateral labyrinthectomy (UL) induced by injection of arsanilate into the middle ear cavity, chemical labyrinthectomy, or surgical labyrinthectomy in medial vestibular nuclei (MVN), prepositus hypoglossal nuclei (PrH), and inferior olivary nuclei (ION) of Sprague-Dawley rats. Number of spontaneous nystagmus in surgical labyrinthectomy group was 28.2+/-.2 beats/10 sec at post-op 2 hs and the nystagmus disappeared 76 hs after UL. In chemical labyrinthectomy group, spontaneous nystagmus occurred 6 hs after UL and increased up to maximum at 12 hs and disappeared 96 hs. Head deviation in surgical labyrinthectomy group reached a peak at post-op 2 hs and recovered to control level at 144 hs, but chemical labyrinthectomy produced head deviation 24 hs after UL and increased degree of the deviation over time till 144 hs. Expression of c-Fos protein in surgical labyrinthectomy group at post-op 2 hs was 81+/-9.4 cells in ipsilateral MVN to the lesion side and 212+/-0 cells in contralateral MVN, which showed severe asymmetry between bilateral MVN, and decrease of c-Fos protein expression was more in contralateral MVN than in ipsilateral MVN at 6 hs. Chemical labyrinthectomy expressed more c-Fos protein in contralateral MVN 6 hs after UL and in ipsilateral MVN 12 hs after UL, which showed asymmetry of c-Fos protein expression between bilateral MVN. And the expression in ipsilateral MVN of chemical labyrinthectomy group was increased gradually 48 hs after UL and reached a peak at 72 hs. In chemical labyrinthectomy group, expression of c-Fos protein in PrH was increased more in ipsilateral than in contralateral 6 hs after UL and more in contralateral 12 hs after UL, and ION showed more expression of c-Fos protein in contralateral than in ipsilateral 6 hs after UL through 72 hs. These results suggest that the course of vestibular compensation and the temporal expression of c-Fos protein in the brain stem nuclei following UL differed between surgical and chemical labyrinthectomy.

THE ULTRASTRUCTURAL CHARACTERISTICS OF THE DORSAL ACCESSORY OLIVARY NUCLEUS IN THE RABBIT / 解剖学报

The dorsal accessory olivary nucleus was studied with electron microscope in seven rabbits.The axo-axonal synapses,an axon being in contact synaptically with a spine of a perikaryon,the glomerulus with an axonal core and a bundle of microfibers within a nucleus of a neuron,as well as the already discovered axo- dendritic synapses,axo-somatic synapses and glomeruli with dendritic cores,were observed in this nucleus. The axo-dendritic synapses were often seen,the postsynaptic components of them were dendrites or spines.The axo-somatic synapses were fewer.An axonal terminal was seen synapsing to both a spine of a perikaryon and a dendrite.Both the presynaptic and postsynaptic components of the axo-axonal synapses contained spherical vesicles.Sometimes the axo-axo-dendritic synapses were observed.There were two kinds of glomeruli in this nucleus,one with dendritic core and the other axonal core.Two axons were discovered simultaneously synapsing with an axon. The complex synaptic pattern in the dorsal accessory olivary nucleus indicated that the afferent impulses would undergo diffusing,converging,presynaptic inhibition or integrating in this nucleus.

THE SYNAPTIC CHARACTERISTICS OF THE SPINO-OLIVARY PROJECTION IN THE RABBIT——AN ELECTRON' MICROSCOPE STUDY WITH THE ANTEROGRADE HORSERADISH PEROXIDASE METHOD / 解剖学报

Horseradish peroxidase (HRP) was injected into the lumbar enlargement of the spinal cord of the rabbit. A lot of anterograde labeled terminals were observed in the contralateral dorsal accessory olivary nucleus. The synapses contacting these labeled terminals were studied with electron microscope. Most of the labeled terminals contained spherical clear vesicals, only a few of them contained flat or pleomorphic cIear vesicles. The labeled terminals were mainly in contact with dendrites, a few contacting with the perikarya. One of the labeled terminals containsd both round and flat clear vesicoles, presynapticto a dendrite and a perikaryonrespectively. It was notabte that a few of the labeled terminals were included in axon-axonal synapses and glumeruli. The functional meaning of these special structures was discussed tentatively.