István Valálik

The application of image fusion in stereotactic brachytherapy of brain tumours.

Summary Background. The visualization of any morphological volume (i.e. CT, MRI) together with an additional second morphological volume (i.e. CT, MRI) or functional data set, which may come from SPECT or PET, is a new method for treatment planning, verification and follow-up of interstitial irradiation. Method. The authors present their experience on interstitial irradiation of brain tumours with stereotactically implanted I-125 seeds supported by image fusion. The image fusion was performed by the BrainLab-Target 1.13 software on Alfa 430 (Digital) workstation before, during, and after interstitial irradiation of brain tumours with Iodine125 seeds. Results and Interpretation. On the basis of 20 brachytherapeutic image fusion of stereotactic CT (slices with fiducials) with additional stereotactic CT, MRI, PET and SPECT images provides more accurate and precise target volume, more exact localization of catheters and isotope seeds (verification fusion), differentiation between the localization and amount of the necrotic and proliferating parts of the tumours and shows the volume changes in consequence of interstitial irradiation. The image fusion should help to improve the accuracy and minimize the perifocal morbidity of interstitial irradiation.

Target identification for stereotactic thalamotomy using diffusion tractography.

Background Stereotactic targets for thalamotomy are usually derived from population-based coordinates. Individual anatomy is used only to scale the coordinates based on the location of some internal guide points. While on conventional MR imaging the thalamic nuclei are indistinguishable, recently it has become possible to identify individual thalamic nuclei using different connectivity profiles, as defined by MR diffusion tractography. Methodology and Principal Findings Here we investigated the inter-individual variation of the location of target nuclei for thalamotomy: the putative ventralis oralis posterior (Vop) and the ventral intermedius (Vim) nucleus as defined by probabilistic tractography. We showed that the mean inter-individual distance of the peak Vop location is 7.33 mm and 7.42 mm for Vim. The mean overlap between individual Vop nuclei was 40.2% and it was 31.8% for Vim nuclei. As a proof of concept, we also present a patient who underwent Vop thalamotomy for untreatable tremor caused by traumatic brain injury and another patient who underwent Vim thalamotomy for essential tremor. The probabilistic tractography indicated that the successful tremor control was achieved with lesions in the Vop and Vim respectively. Conclusions Our data call attention to the need for a better appreciation of the individual anatomy when planning stereotactic functional neurosurgery.

Iodine-125 Brachytherapy of Brain Stem Tumors

Purpose:To report on iodine-125 (125I) interstitial irradiation in the treatment of brain stem tumors.Patients and Methods:Two patients with brain stem tumors were treated with CT- and image fusion-guided 125I stereotactic brachytherapy.Results:By March 2003, the patients had been followed up for 47 and 13 months, respectively. In case 1, the tumor volume was 1.98 cm3 on the control CT, indicating a 65.5% shrinkage as compared to a target volume of 5.73 cm3 at the time of brachytherapy. In case 2, shrinkage was more distinct. After irradiation, the cyst volume was 0.16 cm3 on the control MRI, indicating a 97.4% shrinkage as compared to a target volume of 6.05 cm3 at the time of brachytherapy, i. e., the metastasis had virtually disappeared.Conclusion:CT- and image fusion-guided 125I stereotactic brachytherapy can be performed during the biopsy session. The procedure can be well planned dosimetrically and is surgically precise.Ziel:Beschreibung der interstitiellen Jod-125-(125I-)Brachytherapie bei der Behandlung von Hirnstammtumoren.Patienten und Methodik:Bei zwei Patienten mit Hirnstammtumoren wurde eine durch CT und Fusionsbild gesteuerte interstitielle 125I-Brachytherapie durchgeführt.Ergebnisse:Bis März 2003 betrugen die Nachuntersuchungszeiten der beiden Patienten 47 bzw. 13 Monate. Im ersten Fall lag das Tumorvolumen auf dem Kontroll-CT bei 1,98 cm3, was eine Schrumpfung um 65,5% anzeigte. Im zweiten Fall fiel diese Änderung deutlicher aus. Das Kontroll-MRT ergab eine Schrumpfung von 97,4%, d. h., die Metastase war praktisch verschwunden.Schlussfolgerung:Die durch CT und Fusionsbild gesteuerte interstitielle 125I-Brachytherapie lässt sich dosimetrisch gut planen, und die Methode ist chirurgisch präzise.

Effectiveness of unilateral pallidotomy for meige syndrome confirmed by motion analysis.

Background: We report the case of a 64-year-old woman with bilateral manifestation of Meige syndrome (MS) successfully treated with left-side unilateral ventroposterolateral pallidotomy. Methods: Symptoms were evaluated according to the Burke-Fahn-Marsden dystonia rating scale. Head tremor, blepharospasm and orofacial dyskinesia were measured with an infrared, video-based, computerized, real-time passive marker-based analyzer of motions (RTPAM). Results: The Burke-Fahn-Marsden score showed a 90.2% reduction (from 25.5 to 2.5) at 6 months, and an 88.2% long-lasting benefit (to 3.0) at the 3-year follow-up with good bilateral control of the blepharospasm and orofacial movements. The RTPAM showed a substantial regression of acceleration for all markers, and abolishment of the 4.8-Hz head tremor. The correlation between symmetrical markers, and between markers within the right and left sides, was significantly decreased. Conclusions: Pallidotomy with staged procedure is recommended for the treatment of MS in patients on whom deep brain stimulation could not be performed. In case of good bilateral benefits from the unilateral procedure, contralateral surgery is not needed. The RTPAM is a useful tool for the mapping of facial involuntary movements.

Early experiences with a novel (robot hand) technique in the course of microneurosurgery

BACKGROUND The physiologic tremor may cause difficulties in microsurgery, in spite of using armrest. The new (robot hand) technique consists of the I-III finger support, which holds the instruments on Bethlehem (ANDAN BT, Budapest, Hungary) bridge above the operation area, which reduces the tremor at the end of the instruments. METHODS Exact measurement of tremor reduction was performed. Last year, 23 microsurgical cases were operated on by the robot hand technique. RESULTS The tremors of the operating hand and the number of complications have decreased effectively. CONCLUSION By this technique, the microsurgical work has become more precise.

CT-Guided Unilateral Thalamotomy with Macroelectrode Mapping for the Treatment of Parkinson's Disease

Summary.Summary.Objective: To evaluate the effect of unilateral thalamotomy in patients with Parkinsons disease.Methods: The junction of the ventralis oralis posterior and ventralis intermedius nuclei targeted under CT-guidance, and confirmed by impedance recording and macrostimulation.Results: At the 6-month assessment the tremor has been completely abolished in 37 patients (82.2%), and reduced in 6 patients (13.3%). The Unified Parkinsons Disease Rating Scale tremor score decreased by 92.5%, rigidity improved by 65.9%. Axial symptoms and bradykinesia showed smaller improvement. The levodopa and anti-cholinergic medication significantly reduced. An improvement in the quality of life measured by the Parkinsons Disease Questionnaire (PDQ-39) has been observed. The dimensions of mobility, activities of daily living, emotional well being, and stigma were significantly (P<0.05) better, other changes were not significant. The single index improved from 47.8±7.8 to 28.9±6.3. Transient complications noted in 9 patients (20%), mild persistent morbidity observed in 3 patients (6.7%). At the 1, 2 and 3-year follow-up neither contralateral tremor, rigidity, nor bradykinesia progression was statistically significant.Conclusions: CT-guided thalamotomy with macro-electrode mapping provides a safe, effective and long lasting control of tremor and rigidity, reduces the need for medication, and improves the quality of life.

Voice acoustic changes during bilateral subthalamic stimulation in patients with Parkinson's disease

OBJECTIVES The purpose of this study was to investigate the effects of bilateral subthalamic nucleus deep brain stimulation on the phonation of patients with Parkinsons disease in three drug-free conditions: (1) stimulation off, (2) with clinically optimised stimulation parameters, and (3) subthreshold overstimulation, in order to detect differences following voice analysis. PATIENTS AND METHODS Conversational speech and sustained vowel sounds /a/, /i/, /o/, /u/ and high /i/ were recorded from 22 PD patients. Perceptual analysis, perturbation jitter, shimmer, noise-to-harmonics ratio, and nonlinear dynamic analysis (NDA) with detrended fluctuation analysis and recurrence period density entropy were measured and compared to the above conditions. Quadratic discriminant analysis (QDA) was used to investigate stimulation conditions for given acoustic data. RESULTS The changes of perturbation measurements for the above conditions were not significant. With differences between vowels, NDA showed more significant changes and more powerful correlation with perceptual scores than perturbation measurements. NDA was significantly more sensitive during the QDA of the conditions. CONCLUSIONS Acoustic voice analysis of sustained vowels can help with recognizing the overstimulated condition, and, with an appropriate test battery and software package including nonlinear dynamic analysis, it can be a valuable tool for fine adjustments of stimulation parameters.

Pallidal Deep Brain Stimulation and L-Dopa Effect on PET Motor Activation in Advanced Parkinson's Disease

The antiakinetic effect of internal Globus pallidus deep brain stimulation (Gpi‐DBS) in Parkinsons disease is not clear and not either how this effect is modulated by L‐dopa.

In vitro and in vivo surgical and MRI evidence to clarify the effectiveness of the vascular tunnel technique in the course of decompressive craniectomy

Abstract Objective: To demonstrate the efficacy of a vascular protection technique during decompressive craniectomy (DC) which can reduce the risk of secondary venous infarction due to the blocking pressure for venous outflow through bridging veins. Method: The observation was carried out In vitro (cadaver) and in vivo (surgery and magnetic resonance imaging) in order to verify the durability of the vascular tunnel. Results: in vivo observation proved the durability of vascular tunnel even 2 months later. The cadaveric experimental model showed that after the 12×13 cm size DC had been obtained, the observed vein was occluded at 18-21 mmHg without vascular protection; however, the control preparation remained open even at 50 mmHg. Conclusion: The in vivo case study and the cadaver experiment suggest that vascular protection helps prevent secondary venous infarction after DC. This is therefore an aid in preventing further injury and cerebral oedema. The vascular tunnel guarantees the efficacy of DC even at a high level of intracranial pressure.

CORRESPONDENCE: LETTERS: Fingertip support technique and instrument support for reducing unintentional instrument movements in otology

Sir, Physiological tremor is a main risk factor in microsurgery and the range of tremor magnitude varies widely. Our team developed two simple but very effective low-cost techniques for the reduction of physiological tremor. ‘Fingertip support’ technique (FS) is basically a mechanical support called ‘bridge’ for the first three (instrument holding) fingers of the surgeon. This bridge can be placed both above and near the operating site (Fig. 2). This technique eliminates interference from all of the joints trans-