Clinical Neuroscience

[How does the brain create rhythms?]

SZIRMAI Imre

JANUARY 30, 2010

Clinical Neuroscience - 2010;63(01-02)

[Connection was found between rhythmic cortical activity and motor control. The 10 Hz μ-rhythm and the 20-30 Hz bursts represent two functional states of the somatomotor system. A correspondence of the central μ-rhythm of the motor cortex and the physiological hand tremor (8-12 Hz) is presumed. The precise tuning of the motor system can be estimated by the frequency of repetitive finger movements. In complex tapping exercise, the index finger is the most skillful, the 3rd, 4th and 5th fingers keep rhythm with less precision. It was found that the organization of mirror movements depends on the cortical representation of fingers. Mirror finger movements are more regular if the subject begins the motor action with the 5th (small) finger. Concerning cortical regulation of finger movements, it was suggested that there are two time-keeping systems in the brain; one with a sensitivity above and another with a sensitivity below the critical frequency of 3 Hz. The preferred meter which helps to maintain synchronous finger movements is the cadence of 4/4 and 8/8. We observed that the unlearned inward-outward sequential finger movement was equally impaired in nonmusician controls and patients with Parkinson-disease. In movement disorders, the ability of movement and the “clock-mechanism” are equally involved. The polyrhythmic finger movement is not our inborn ability, it has to be learned. The “timer” function, which regulates the rhythmic movement, is presumably localised in the basal ganglia or in the cerebellum. The meter of the music is built on the reciprocal values of 2 raised to the second to fifth power (1/12, 1/22, 1/23, 1/24, 1/25). The EEG frequencies that we consider important in the regulation of cons-cious motor actions are approximately in the same domain (4, 8, 16, 32, 64 Hz). During music performance, an important neural process is the coupling of distant brain areas. Concerning melody, the musical taste of Europeans is octavebased. Musical ornaments also follow the rule of the gothic construction, that is: pursuit of harmony towards the single one rising from the unification of 8-4-2 classes. Leibnitz concerned music as the unconscious mathematics of the soul. Movement-initiating effect of music is used in rehabilitation of patients with movement disorders. The meter and rhythm have superiority over the melody. It is possible that rhythmic movements can be generated also in the absence of sensory input and the central oscillators can produce “fictive motor patterns”.]

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Clinical Neuroscience

[Frontotemporal dementia, Pick’s disease]

ANDREW Kertesz

[A significant expansion of knowledge in the last few years, especially in the molecular biology of frontotemporal dementia (FTD) is summarized. This condition, formerly known as Pick’s disease and considered rare, is estimated to be 12-15% of all dementias and 30-50% early onset ones. The clinical picture is protean, mainly a behavioural and language impairment, but the extrapyramidal syndromes of CBD and PSP also belong. These seemingly different presentations converge, as one or other areas in the brain are affected. Less than half of the cases are tauopathies, the majority has been discovered to have a TDP-43 and most recently a FUS proteinopathy, shared with ALS, opening potential opportunities for pharmacological approaches to treatment. Tau and progranulin mutations on Ch-17 and some others, point to molecular mechanisms. A glossary is provided to navigate the complex terminology.]

Clinical Neuroscience

[Anterior cervical fusion on the lower cervical spine: own clinical experiences]

PAZDERNYIK Szilárd, SÁNDOR László, ELEK Péter, BARZÓ Pál

[Both acute and chronic instability of the cervical spine can be succesfully treated by anterior crevical fusion. The main goal is to create a spondylodesis through which the instable motion segments are fixed in the position defined by the surgeon. The spondylodesis is realised by the bone healing of the intervertebral space. The consolidation itself is facilitated by the operative stabilisation of the segments involved, and also by the implantation/transplantation of the osteoproductive/ osteoinductive materials. The sooner consolidation is achieved, the more likely it is to be able to avoid the material dependent complications and/or that of dislocation. So as to support this theory a retrospective clinical/radiological study was performed. During this the length and the safety of the consolidation was measured by applying various anterior cervical plating systems. A total of 485 patients having cervical injuries or degenerative disc disease were treated by anterior cervical plating. For bone transplantation partly pure autolog spongious partly autolog cortico-spongious morsalised bone chips, furthermore autolog tricortical bone block were applied. A standard protocoll was used for data collection, evaluation and also follow-up. The patients treated with plate systems were divided into 3 groups: Group 1: Non-locked H-plate system with autogeneous cancellous bone (155 trauma patients, for a total of 210 cervical motion segments, 1.35 segments/patients). Group 2: Non-locked H-plate system with tricortical autograft (167 patients, for a total of 290 cervical motion segments, 1.73 segments/patients). Group 3: Locked cervical plate system with tricortical autograft (73 patients, for a total of 110 cervical motion segments, 1.5 segments/patients). Patients treated with standalone cage belong to group 4. These cages were filled with autogenous cortico-spongiosus bone chips (90 patients, for a total of 90 cervical motion segments, 1.0 segments/patients). Evaluations included postoperative clinical, X-ray and CT examination, and follow-ups at 6, 16, 52, and 104 weeks. We established three grades, and classified the degree of bony fusion between the graft and vertebra: not-yet-fused, fused or non-union. When evaluating the results the following statements/observations were made: a) There is a fast and safe consolidation in the case of those patients that underwent dinamic disc osteosynthesis (p=0.00001). b) Whereas performing fixation with non-locked or locked screw plate systems and strutgrafted with tricortical autograft created prolonged healing requiring months and developed non-unions more often (non-locked screw-plate system versus locked screwplate system) (p>0.05). c) Using locked screw-plate fixation systems non-union rate in our study was 21%, suggesting that this form of fixation has only a limited use. d) In our study complete consolidation without pseudoarthrosis was achieved by using standalone cages filled with autolog cortico- spongiosus bone chips, but bony healing was delayed due to cage coating and the substitution of pure autogenous spongiosa for cortico-spongiosus bone chips. It is recommended to treat acute/chronic instability of the cervical spine both by using non-fixed plate system with autolog cancellosus bone and by standalone cage filled with cortico-spongiosus bone chips as well. It is worth keeping in mind that by applying this lattest an extra surgery to harvest the graft will be avoided.]

Clinical Neuroscience

[Extracellular matrix of intracerebral tumors with different invasion activity]

KLEKNER Álmos, VARGA Imre, BOGNÁR László, HUTÓCZKI Gábor, KENYERES Annamária, TÓTH Judit, HANZÉLY Zoltán, SCHOLTZ Beáta

[Objectives - Ineffective surgical and radiotherapy of glioblastoma is mainly due to its intensive infiltrating behavior. Contrarily, brain metastases of anaplastic carcinomas are well-circumscribed intracerebral lesions that can be easily exstirpated in most cases. The molecules of the extracellular matrix (ECM) play a pivotal role in the peritumoral infiltration. In this study the mRNA expression of the ECM components was investigated in two types of intracerebral malignoma with different invasion activity. Our aim was to identify the ECM molecules that are responsible for the different intensity of peritumoral infiltration of tumors from different origin. Methods - The mRNA expression of twenty-three ECM molecules was determined by quantitative reverse transcriptase polymerase chain reaction. Four pieces of glioblastoma and four pieces of intracerebral lung adenocarcinoma metastasis from neurosurgical operation were investigated. Immunohistochemical investigations were performed in case of five molecules. Results - The mRNA expression of nine molecules (brevican, neurocan, neuroglycan-C, syndecan-1,2,4, tenascin-C, versican and matrix-metalloproteinase-[MMP]2) differed significantly by comparison of the two tumor types. By immunohistochemistry, neurocan, syndecan, versican and MMP-2 showed alteration in staining intensity according to the mRNA expression, while MMP-9 showed higher staining intensity in the metastatic tumor. Conclusions - The identified molecules can play an important role in the different infiltration activity of tumors from different origin. Thus these ECM-components could serve as targets for anti-invasion therapy in the future.]

Clinical Neuroscience

[Posterior cortical atrophy (Benson-syndrome)]

RÓZSA Anikó, SZILVÁSSY Ildikó, KOVÁCS Krisztina, BOÓR Krisztina, GÁCS Gyula

[We present the characteristics of posterior cortical atrophy - a very rare cortical dementia - in a 69 year old woman’s case. Our patient’s symptoms began with a visual problem which was initially explained by ophthalmological disorder. After neurological exam visual agnosia was diagnosed apart from other cognitive disorder (alexia without agraphia, acalculia, prosopagnosia, constructional disorder, clock-time recognition disorder, dressing apraxia, visuospatial disorientation). The brain MRI showed bilateral asymmetric parieto-occipital atrophy which is characteristic of posterior cortical atrophy.]

Clinical Neuroscience

[Molecular genetic mutation analysis in Menkes-disease with prenatal diagnosis]

LÁSZLÓ Aranka, ENDREFFY Emőke, TÜMER Zeynep, HORN Nina, SZABÓ János

[Menkes disease (MD) is an X-linked recessive multisystemic lethal, heredodegenerative disorder. Progressive neurodegeneration and connective tissue disturbances with microscopically kinky hair are the main symptoms. Molecular genetic mutation analysis was made at a Hungarian male infant suffering from MD and prenatal diagnosis was done in this MD loaded family. Method - The 12th exon of ATP7A gene has been analyzed by dideoxy-finger printing (DDF), polymerase chain reaction (PCR), direct sequencing of exon 12. The specific mutation was screened from chorionic villi of the maternal aunt at the 14th gestational week. Results - In the exon 12th a basic pair substitution with Arg 844 His change was detected leading to very severe fatal missense mutation.]

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Although vertigo is one of the most common complaints, intracranial malignant tumors rarely cause sudden asymmetry between the tone of the vestibular peripheries masquerading as a peripheral-like disorder. Here we report a case of simultaneous temporal bone infiltrating macro-metastasis and disseminated multi-organ micro-metastases presenting as acute unilateral vestibular syndrome, due to the reawakening of a primary gastric signet ring cell carcinoma. Purpose – Our objective was to identify those pathophysiological steps that may explain the complex process of tumor reawakening, dissemination. The possible causes of vestibular asymmetry were also traced. A 56-year-old male patient’s interdisciplinary medical data had been retrospectively analyzed. Original clinical and pathological results have been collected and thoroughly reevaluated, then new histological staining and immunohistochemistry methods have been added to the diagnostic pool. During the autopsy the cerebrum and cerebellum was edematous. The apex of the left petrous bone was infiltrated and destructed by a tumor mass of 2x2 cm in size. Histological reexamination of the original gastric resection specimen slides revealed focal submucosal tumorous infiltration with a vascular invasion. By immunohistochemistry mainly single infiltrating tumor cells were observed with Cytokeratin 7 and Vimentin positivity and partial loss of E-cadherin staining. The subsequent histological examination of necropsy tissue specimens confirmed the disseminated, multi-organ microscopic tumorous invasion. Discussion – It has been recently reported that the expression of Vimentin and the loss of E-cadherin is significantly associated with advanced stage, lymph node metastasis, vascular and neural invasion and undifferentiated type with p<0.05 significance. As our patient was middle aged and had no immune-deficiency, the promoting factor of the reawakening of the primary GC malignant disease after a 9-year-long period of dormancy remained undiscovered. The organ-specific tropism explained by the “seed and soil” theory was unexpected, due to rare occurrence of gastric cancer to metastasize in the meninges given that only a minority of these cells would be capable of crossing the blood brain barrier. Patients with past malignancies and new onset of neurological symptoms should alert the physician to central nervous system involvement, and the appropriate, targeted diagnostic and therapeutic work-up should be established immediately. Targeted staining with specific antibodies is recommended. Recent studies on cell lines indicate that metformin strongly inhibits epithelial-mesenchymal transition of gastric cancer cells. Therefore, further studies need to be performed on cases positive for epithelial-mesenchymal transition.

Clinical Neuroscience

Atypical presentation of late-onset Sandhoff disease: a case report

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Sandhoff disease is a rare type of hereditary (autosomal recessive) GM2-gangliosidosis, which is caused by mutation of the HEXB gene. Disruption of the β subunit of the hexosaminidase (Hex) enzyme affects the function of both the Hex-A and Hex-B isoforms. The severity and the age of onset of the disease (infantile or classic; juvenile; adult) depends on the residual activity of the enzyme. The late-onset form is characterized by diverse symptomatology, comprising motor neuron disease, ataxia, tremor, dystonia, psychiatric symptoms and neuropathy. A 36-year-old female patient has been presenting progressive, symmetrical lower limb weakness for 9 years. Detailed neurological examination revealed mild symmetrical weakness in the hip flexors without the involvement of other muscle groups. The patellar reflex was decreased on both sides. Laboratory tests showed no relevant alteration and routine electroencephalography and brain MRI were normal. Nerve conduction studies and electromyography revealed alterations corresponding to sensory neuropathy. Muscle biopsy demonstrated signs of mild neurogenic lesion. Her younger brother (32-year-old) was observed with similar symptoms. Detailed genetic study detected a known pathogenic missense mutation and a 15,088 base pair long known pathogenic deletion in the HEXB gene (NM_000521.4:c.1417G>A; NM_000521:c.-376-5836_669+1473del; double heterozygous state). Segregation analysis and hexosaminidase enzyme assay of the family further confirmed the diagnosis of late-onset Sandhoff disease. The purpose of this case report is to draw attention to the significance of late-onset Sandhoff disease amongst disorders presenting with proximal predominant symmetric lower limb muscle weakness in adulthood.

Clinical Neuroscience

Neuroscience highlights: The mirror inside our brain

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Over the second half of the 19th century, numerous theories arose concerning mechanisms involved in understanding of action, imitative learning, language development and theory of mind. These explorations gained new momentum with the discovery of the so called “mirror neurons”. Rizzolatti’s work inspired large groups of scientists seeking explanation in a new and hitherto unexplored area of how we perceive and understand the actions and intentions of others, how we learn through imitation to help our own survival, and what mechanisms have helped us to develop a unique human trait, language. Numerous studies have addressed these questions over the years, gathering information about mirror neurons themselves, their subtypes, the different brain areas involved in the mirror neuron system, their role in the above mentioned mechanisms, and the varying consequences of their dysfunction in human life. In this short review, we summarize the most important theories and discoveries that argue for the existence of the mirror neuron system, and its essential function in normal human life or some pathological conditions.

Clinical Neuroscience

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Clinical Neuroscience

Neuroscience highlights: Main cell types underlying memory and spatial navigation

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