Clinical Neuroscience

[Transcranial direct current stimulation in neuroscientific researches – pitfalls and solutions]

PESTHY Orsolya1,2, JANACSEK Karolina2,3,4, NÉMETH Dezső2,3,5

MAY 30, 2021

Clinical Neuroscience - 2021;74(5-6)


[Transcranial direct current stimulation (tDCS) is a promising brain stimulation tool which is non-invasive, easy to use and relatively cheap. Since it can change brain activity in a temporal manner, it can contribute to both clinical practice and neuroscientific research. However, the effectiveness of tDCS has been questioned considering the lack of full understanding of its mechanism of action and the seemingly contradictory results. In this review, we aim to provide a summary of potential problems and possible solutions. Our main focus is on the inter-individual differences in the effect of tDCS which can explain the noisy data, thus, controlling for them is important in order to show reliable results. This review is hoped to contribute to maximizing the potential of tDCS by helping future researchers to design replicable studies.]


  1. Eötvös Loránd Tudományegyetem, Pszichológiai Doktori Iskola, Budapest
  2. Eötvös Loránd Tudományegyetem, Pszichológiai Intézet, Budapest
  3. Kognitív Idegtudományi és Pszichológiai Intézet, Természettudományi Kutatóközpont, Emlékezet, Nyelv és Idegtudomány Kutatócsoport, Budapest
  4. School of Human Sciences, Faculty of Education, Health and Human Sciences, University of Greenwich, Greenwich, Egyesült Királyság
  5. Lyon Neuroscience Research Center, INSERM, CNRS, Université de Lyon, Lyon, Franciaország



Further articles in this publication

Clinical Neuroscience

Comparison of direct costs of percutaneous full-endoscopic interlaminar lumbar discectomy and microdiscectomy: Results from Turkey

ÜNSAL Ünlü Ülkün, ŞENTÜRK Salim

Microdiscectomy (MD) is a stan­dard technique for the surgical treatment of lumbar disc herniation (LDH). Uniportal percutaneous full-endoscopic in­terlaminar lumbar discectomy (PELD) is another surgical op­tion that has become popular owing to reports of shorter hos­pitalization and earlier functional recovery. There are very few articles analyzing the total costs of these two techniques. The purpose of this study was to compare total hospital costs among microdiscectomy (MD) and uniportal percutaneous full-endoscopic interlaminar lumbar discectomy (PELD). Forty patients aged between 22-70 years who underwent PELD or MD with different anesthesia techniques were divided into four groups: (i) PELD-local anesthesia (PELD-Local) (n=10), (ii) PELD-general anesthesia (PELD-General) (n=10), (iii) MD-spinal anesthesia (MD-Spinal) (n=10), (iv) MD-general anesthesia (MD-General) (n=10). Health care costs were defined as the sum of direct costs. Data were then analyzed based on anesthetic modality to produce a direct cost evaluation. Direct costs were compared statistically between MD and PELD groups. The sum of total costs was $1,249.50 in the PELD-Local group, $1,741.50 in the PELD-General group, $2,015.60 in the MD-Spinal group, and $2,348.70 in the MD-General group. The sum of total costs was higher in the MD-Spinal and MD-General groups than in the PELD-Local and PELD-General groups. The costs of surgical operation, surgical equipment, anesthesia (anesthetist’s costs), hospital stay, anesthetic drugs and materials, laboratory wor­kup, nur­sing care, and two main groups (PELD-MD) me­dication diffe­red significantly among the two main groups (PELD-MD) (p<0.01). This study demonstrated that PELD is less costly than MD.

Clinical Neuroscience

[The questions of the treatment of Parkinson’s disease]

NAGY Ferenc

[Despite the continuous development of diagnosis and treatment of patients with Parkinson’s disease and the arrival of new therapeutic options in recent years the treatment and care of people with Parkinson’s disease especially in the advanced stage remains a major challenge for neurologists specialized in movement disorders. The treatment of Parkinson’s disease is adversely affected by several factors: the disease progresses relentlessly, the symptoms and rate of progression, other concomitant non-motor symptoms, and the appearance of complications caused by treatment show great heterogeneity. Based on all these factors it is difficult to develop and apply a uniform routine therapeutic guideline. This summary seeks to shed light on aspects of the treatment of Parkinson’s disease particularly in advanced-stage cases drawing on data from a professional college recommendation and the literature.]

Clinical Neuroscience

A new method to determine the optimal orientation of Slim Modiolar cochlear implant electrode array insertion

HORVÁTH Bence, PERÉNYI Ádám, MOLNÁR Fiona Anna, CSANÁDY Miklós, KISS József Géza, ROVÓ László

Our goal was to determine the optimal orientation of insertion of the Slim Modiolar electrode and develop an easy-to-use method to aid implantation surgery. In some instances, the electrode arrays cannot be inserted in their full length. This can lead to buckling, interscalar dislocation or tip fold-over. In our opinion, one of the possible reasons of tip fold-over is unfavourable orientation of the electrode array. Our goal was to determine the optimal orientation of the Slim Modiolar electrode array relative to clear surgical landmarks and present our method in one specified case. For the measurement, we used the preoperative CT scan of one of our cochlear implant patients. These images were processed by an open source and free image visualization software: 3D Slicer. In the first step we marked the tip of the incus short process and then created the cochlear view. On this view we drew two straight lines: the first line represented the insertion guide of the cochlear implant and the second line was the orientation marker (winglet). We determined the angle enclosed by winglet and the line between the tip of the incus short process and the cross-section of previously created two lines. For the calculation we used a self-made python code. The result of our algorithm for the angle was 46.6055°. To validate this result, we segmented, from the CT scan, the auditory ossicles and the membranaceous labyrinth. From this segmentation we generated a 3D reconstruction. On the 3D view, we can see the position of the previous lines relative to the anatomical structures. After this we rotated the 3D model together with the lines so that the insertion guide forms a dot. In this view, the angle was measured with ImageJ and the result was 46.599°. We found that our method is easy, fast, and time-efficient. The surgery can be planned individually for each patient, based on their routine preoperative CT scan of the temporal bone, and the implantation procedure can be made safer. In the future we plan to use this method for all cochlear implantation surgeries, where the Slim Modiolar electrode is used.

Clinical Neuroscience

Fatal outcome of cervical myelopathy caused by fibrocartilaginous embolism. Rare cause of spinal vascular damage

FOLYOVICH András, HAVAS László, VADÁSZ Gizella, FEHÉR Ágnes, VADASDI Károly, SZABÓ Zsolt, TÓTH Kornélia, BÉRES-MOLNÁR Anna Katlin, TOLDI Gergely

Fibrocartilaginous embolism is a rare cause of ischemic myelopathy. Authors report a case of a 39-year-old woman with progressive tetraparesis and severe autonomic dysfunction. Despite of the detailed examinations, the definite diagnosis was verified by autopsy. The patient was admitted because of progressive pain and numbness of the upper extremities and tetraparesis. Hypotonic muscles of the lower extremities with mild tetraparesis were observed. Magnetic resonance imaging showed an intramedullary lesion at the level of the cervical V-VII vertebral. Patient’s tetraparesis worsened gradually to plegia with urinary retention. Expansive, rapidly progressing multiple decubiti developed, which were resistant to therapy. In spite of the complex therapy, the patient died. No internal disease was found to explain the death by autopsy. Multiple subacute infarctions of the cervical myelon (involving the lateral columns as well) in the territory of the anterior spinal artery were verified by neuropathological examination. The occluded vessels were filled by a material containing cartilaginous cells, while signs of atherosclerosis or thrombosis were not present. Cartilaginous embolism of spinal arteries was diagnosed.

Clinical Neuroscience

[A case of destructive cervical spondylarthropathy related to chronic dialysis]

BERTA Balázs, KOMÁROMY Hedvig, SCHWARCZ Attila, KAJTÁR Béla, BÜKI András, KUNCZ Ádám

[A case of a 61-year-old male patient suffered chronic renal failure and dialysed for 23 years with destructive cervical spondylarthropathy is presented. The patient presented with sudden onset of cervical pain radiating into his shoulders without neurological deficits. CT and MRI of the cervical and thoracic spine revealed severe destructive changes and compressive fractures of C6 and C7 vertebrae which caused the narrowing of the nerve root canals at these levels. A 360-degree fixation was performed to treat the unstable fracture and the patient’s pain (C6 and C7 corpectomy, autolog bone graft replacement of the two vertebral bodies, anterior plate fixation and posterior instrumentation with screws and rods). Postoperatively the patient had no significant pain, no neurological deficit and he was able to manage independent life himself. During the immediate follow-up CT of the neck showed the satisfactory position of the bone graft and the metal implantations. The 6 months follow-up CT revealed the anterior migration of the two screws from the Th1 vertebral body and 2 mm ventral elevation of the caudal end of the plate from the anterior surface of the Th1 vertebral body. The 1-year follow-up could not be performed because the patient died due to cardio-pulmonary insufficiency. This is the second Hungarian report of a chronic dialysis related severe spondylarthropathy which may cause pathologic fractures of the vertebral bodies. The typical radiological and histological findings are discussed. This disease affect patients’ quality of life and the conservative treatment alone seems to be ineffective in most cases. Based on the literature and personal experiences, the authors suggest 360-degree fixation of the spine to provide sufficient stability for the vertebrae of ”bad bone quality”, and early mobilisation of the patient can be achieved.]

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Clinical Neuroscience

Late simultaneous carcinomatous meningitis, temporal bone infiltrating macro-metastasis and disseminated multi-organ micro-metastases presenting with mono-symptomatic vertigo – a clinico-pathological case reporT

JARABIN András János, KLIVÉNYI Péter, TISZLAVICZ László, MOLNÁR Anna Fiona, GION Katalin, FÖLDESI Imre, KISS Geza Jozsef, ROVÓ László, BELLA Zsolt

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

Cases of inborn errors of metabolism diagnosed in children with autism

CAKAR Emel Nafiye, YILMAZBAS Pınar

Autism spectrum disorder is a neurodevelopmental disorder with a heterogeneous presentation, the etiology of which is not clearly elucidated. In recent years, comorbidity has become more evident with the increase in the frequency of autism and diagnostic possibilities of inborn errors of metabolism. One hundred and seventy-nine patients with diagnosis of autism spectrum disorder who presented to the Pediatric Metabolism outpatient clinic between 01/September/2018-29/February/2020 constituted the study population. The personal information, routine and specific metabolic tests of the patients were analyzed retrospectively. Out of the 3261 patients who presented to our outpatient clinic, 179 (5.48%) were diagnosed with autism spectrum disorder and were included in the study. As a result of specific metabolic examinations performed, 6 (3.3%) patients were diagnosed with inborn errors of metabolism. Two of our patients were diagnosed with classical phenylketonuria, two with classical homocystinuria, one with mucopolysaccharidosis type 3D (Sanfilippo syndrome) and one with 3-methylchrotonyl Co-A carboxylase deficiency. Inborn errors of metabolism may rarely present with autism spectrum disorder symptoms. Careful evaluation of the history, physical examination and additional findings in patients diagnosed with autism spectrum disorder will guide the clinician in the decision-making process and chose the appropriate specific metabolic investigation. An underlying inborn errors of metabolism may be a treatable cause of autism.

Clinical Neuroscience

Alexithymia is associated with cognitive impairment in patients with Parkinson’s disease

SENGUL Yildizhan, KOCAK Müge, CORAKCI Zeynep, SENGUL Serdar Hakan, USTUN Ismet

Cognitive dysfunction (CD) is a common non-motor symptom of Parkinson’s disease (PD). Alexithy­mia is a still poorly understood neuropsychiatric feature of PD. Cognitive impairment (especially visuospatial dysfunction and executive dysfunction) and alexithymia share com­mon pathology of neuroanatomical structures. We hypo­thesized that there must be a correlation between CD and alexithymia levels considering this relationship of neuroanatomy. Objective – The aim of this study was to evaluate the association between alexithymia and neurocognitive function in patients with PD. Thirty-five patients with PD were included in this study. The Toronto Alexithymia Scale–20 (TAS-20), Geriatric Depression Inventory (GDI) and a detailed neuropsychological evaluation were performed. Higher TAS-20 scores were negatively correlated with Wechsler Adult Intelligence Scale (WAIS) similarities test score (r =-0.71, p value 0.02), clock drawing test (CDT) scores (r=-0.72, p=0.02) and verbal fluency (VF) (r=-0.77, p<0.01). Difficulty identifying feelings subscale score was negatively correlated with CDT scores (r=-0.74, p=0.02), VF scores (r=-0.66, p=0.04), visual memory immediate recall (r=-0.74, p=0.01). VF scores were also correlated with difficulty describing feelings (DDF) scores (r=-0.66, p=0.04). There was a reverse relationship bet­ween WAIS similarities and DDF scores (r=-0.70, p=0.02), and externally oriented-thinking (r=-0.77,p<0.01). Executive function Z score was correlated with the mean TAS-20 score (r=-62, p=0.03) and DDF subscale score (r=-0.70, p=0.01) Alexithymia was found to be associated with poorer performance on visuospatial and executive function test results. We also found that alexithymia was significantly correlated with depressive symptoms. Presence of alexithymia should therefore warn the clinicians for co-existing CD.

Clinical Neuroscience

Evaluation of the effectiveness of transforaminal epidural steroid injection in far lateral lumbar disc herniations

EVRAN Sevket, KATAR Salim

Far lateral lumbar disc herniations (FLDH) consist approximately 0.7-12% of all lumbar disc herniations. Compared to the more common central and paramedian lumbar disc herniations, they cause more severe and persistent radicular pain due to direct compression of the nerve root and dorsal root ganglion. In patients who do not respond to conservative treatments such as medical treatment and physical therapy, and have not developed neurological deficits, it is difficult to decide on surgical treatment because of the nerve root damage and spinal instability risk due to disruption of facet joint integrity. In this study, we aimed to evaluate the effect of transforaminal epidural steroid injection (TFESI) on the improvement of both pain control and functional capacity in patients with FLDH. A total of 37 patients who had radicular pain caused by far lateral disc herniation which is visible in their lumbar magnetic resonance imaging (MRI) scan, had no neurological deficit and did not respond to conservative treatment, were included the study. TFESI was applied to patients by preganglionic approach. Pre-treatment Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) scores of the patients were compared with the 3rd week, 3rd month and 6th month scores after the procedure. The mean initial VAS score was 8.63 ± 0.55, while it was 3.84 ± 1.66, 5.09 ± 0.85, 4.56 ± 1.66 at the 3rd week, 3rd month and 6th month controls, respectively. This decrease in the VAS score was found statistically significant (p = 0.001). ODI score with baseline mean value of 52.38 ± 6.84 was found to be 18.56 ± 4.95 at the 3rd week, 37.41 ± 14.1 at the 3rd month and 34.88 ± 14.33 at the 6th month. This downtrend of pa­tient’s ODI scores was found statistically significant (p = 0.001). This study has demonstrated that TFESI is an effective method for gaining increased functional capacity and pain control in the treatment of patients who are not suitable for surgical treatment with radicular complaints due to far lateral lumbar disc hernia.

Clinical Neuroscience

Electrophysiological investigation for autonomic dysfunction in patients with myasthenia gravis: A prospective study


Myasthenia gravis (MG) is an autoimmune disorder of neuromuscular transmission. Autonomic dysfunction is not a commonly known association with MG. We conducted this study to evaluate autonomic functions in MG & subgroups and to investigate the effects of acetylcholinesterase inhibitors. This study comprised 30 autoimmune MG patients and 30 healthy volunteers. Autonomic tests including sympathetic skin response (SSR) and R-R interval variation analysis (RRIV) was carried out. The tests were performed two times for patients who were under acetylcholinesterase inhibitors during the current assessment. The RRIV rise during hyperventilation was better (p=0.006) and Valsalva ratio (p=0.039) was lower in control group. The SSR amplitudes were lower thereafter drug intake (p=0.030). As much as time went by after drug administration prolonged SSR latencies were obtained (p=0.043).Valsalva ratio was lower in the AchR antibody negative group (p=0.033). The findings showed that both ocular/generalized MG patients have a subclinical parasympathetic abnormality prominent in the AchR antibody negative group and pyridostigmine has a peripheral sympathetic cholinergic noncumulative effect.