Stereotaxic Neurosurgery Research Articles

Step-by-step approach: Stereotaxic surgery for in vivo extracellular field potential recording at the rat Schaffer collateral-CA1 synapse using the eLab system

In vivo extracellular field potential recording is a commonly used technique in modern neuroscience research. The success of long-term electrophysiological recordings often depends on the quality of the implantation surgery. However, there is limited use of visually guided stereotaxic neurosurgery and the application of the eLab/ePulse electrophysiology system in rodent models. This study presents a practical and functional manual guide for surgical electrode implantation in rodent models using the eLab/ePulse electrophysiology system for recording and stimulation purposes to assess neuronal functionality and synaptic plasticity. The evaluation parameters included the input/output function (IO), paired-pulse facilitation or depression (PPF/PPD), long-term potentiation (LTP), and long-term depression (LTD).•Provides a detailed picture-guided procedure for conducting in vivo stereotaxic neurosurgery.•Specifically covers the insertion of hippocampal electrodes and the recording of evoked extracellular field potentials.

Refining Stereotaxic Neurosurgery Techniques and Welfare Assessment for Long-Term Intracerebroventricular Device Implantation in Rodents.

Stereotaxic surgeries enable precise access to specific brain regions, being of particular interest for chronic intracerebroventricular drug delivery. However, the challenge of long-term studies at this level is to allow the implantation of drug storage devices and their correct intrathecal connection while guaranteeing animal welfare during the entire study period. In this study, we propose an optimized method for safe intrathecal device implantation, focusing on preoperative, intraoperative, and postoperative procedures, following the 3Rs principle and animal welfare regulations. Our optimized protocol introduces three main refinements. Firstly, we modify the dimensions of the implantable devices, notably diminishing the device-to-mouse weight ratio. Secondly, we use a combination of cyanoacrylate tissue adhesive and UV light-curing resin, which decreases surgery time, improves healing, and notably minimizes cannula detachment or adverse effects. Thirdly, we develop a customized welfare assessment scoresheet to accurately monitor animal well-being during long-term implantations. Taken together, these refinements positively impacted animal welfare by minimizing the negative effects on body weight, surgery-related complications, and anxiety-like behaviors. Overall, the proposed refinements have the potential to reduce animal use, enhance experimental data quality, and improve reproducibility. Additionally, these improvements can be extended to other neurosurgical techniques, thereby advancing neuroscience research, and benefiting the scientific community.

Accurate Neurosurgery for the Establishment of the Electric Kindling Model of Epilepsy in Mice

This article describes in detail the essential stereotaxic neurosurgery to develop the electric experimental kindling model in mice. To date, available literature describing the methodology of the kindling model is very poor and usually neglects many relevant details about the neurosurgery, such as the manufacture of the electrodes, accurate stereotaxic coordinates of the amygdala nuclei, and the general surgery procedures (e.g., anesthesia, postsurgical recovery, fit survival of the animal’s). The electric kindling model produces a progressive development of generalized tonic-clonic seizures, which can be assessed by electroencephalography and behavioral responses. The seizures displayed are produced by a repeated low-intensity electrical stimulation in specific regions of the brain that is achieved through the previous implantation of electrodes. In this study, the aim was to implant the electrodes in basolateral amygdaloid nucleus (BLA). In order to successfully establish the kindling experimental model, neurosurgery to place the electrodes is an essential step to develop the epileptogenic phenomenon. It crucial that the surgery is carried out with exceptional exactitude, because in that way the experimental model represents an accurate and valid tool to study and understand epilepsy and the results obtained can be used to develop further strategies in epilepsy clinical research.

Improving Stereotaxic Neurosurgery Techniques and Procedures Greatly Reduces the Number of Rats Used per Experimental Group—A Practice Report

Simple SummaryStereotaxic surgery techniques are commonly used today in research laboratories by a range of students, technicians, and researchers. Over the past twenty years, technical and scientific progress has been made in neurosurgery to meet the evolving requirements imposed by international legislation, and to promote the implementation of 3R rules. These improvements were motivated by a greater awareness of animal welfare and the necessary effort in the reduction of the number of animals used in experiments. The data presented in the present study show that technical and methodological improvements brought to our surgical procedures from 1992 resulted in reproducible stereotaxic neurosurgeries and in a significant reduction in experimental errors and animal morbidity. The effects of these improvements include a decrease in the final number of animals used in our experiments as well as better management of pain during and after surgery and the use of appropriate aseptic techniques. Correct stereotaxic surgical approaches are precisely described throughout the text.Techniques of stereotaxic surgery are commonly used in research laboratories by a range of students, technicians, and researchers. To meet the evolving requirements imposed by international legislation, and to promote the implementation of 3R rules (replacement, reduction, and refinement) by reducing experimental error, animal morbidity, and mortality, it is essential that standard operating procedures and proper conduct following such complex surgeries be precisely described and respected. The present report shows how refinements of our own neurosurgical techniques over decades, have significantly reduced the number of animals (rats) used in experiments and improved the animals’ well-being during the post-surgical recovery period. The current pre-, per-, and post-surgical procedures used in our laboratory are detailed. We describe the practical aspects of stereotaxic neurosurgery that have been refined in our laboratory since 1992 and that cover various areas including appropriate anesthesia and pain management during and after surgery, methods to determine the stereotaxic coordinates, and the best approach to the target brain structure. The application of these optimal surgical methods that combine reliable and reproducible results with an acute awareness of ethics and animal welfare leads to a significant reduction in the number of animals included in experimental research in accordance with ethical and regulatory rules as required by the European Directive on laboratory animal welfare.

To the 90th anniversary of the birth of Professor Oleg O. Laponogov

The paper is dedicated to the founder of functional neurosurgery in Ukraine — Professor O.A. Laponogov, who would have turned 90 in September 2020. After graduating with honours from Kyiv Medical Institute in 1954, O.A. Laponogov began working at the Kyiv Research Institute of Neurosurgery. In the late 1950s, O.A. Laponogov completed an internship in stereotaxic neurosurgery at M.N. Burdenko Institute of Neurosurgery in Moscow under Professor E.I. Kandel. Upon returning to Kyiv, he introduced stereotaxic operations in the treatment of Parkinson’s disease, tremor, torsion dystonia, and other movement disorders, and also developed a concept for the surgical treatment of epilepsy.Together with engineer A.N. Sikorsky, O.A. Laponogov developed a stereotaxic apparatus of his own design, which combined the advantages of the foreign stereotaxic systems. For the development of this device, he received the Gold Medal at the International Exhibition of Technology in Leipzig in 1972.Thanks to the enthusiasm of Professor O.A. Laponogov, in 1974 at the Kyiv Research Institute of Neurosurgery, one of the first departments of functional neurosurgery in Europe was founded, which he headed for over 35 years. Professor O.A. Laponogov studied the features of the development and management of epilepsy, Parkinson’s disease, torsion dystonia, and other movement disorders, introduced new technologies for the diagnosis and surgical treatment of these diseases.Professor O.A. Laponogov left a rich and valuable legacy and forever went down into the history of the Neurosurgery Institute and Ukrainian neurosurgery as a pioneer and founder of a new direction — functional and stereotactic neurosurgery.

Egg Model Training Protocol for Stereotaxic Neurosurgery and Microelectrode Implantation.

Neuroscience research uses neurosurgery in animal models for several experimental techniques. To our knowledge, there is no published method for small animal neurosurgery training. Based on the similar thickness of chicken eggshells and mouse, rat, and some small primate skulls, here we propose an egg model training protocol for stereotaxic surgery. To perform training it was used a boiled egg and the same materials needed to perform stereotaxic neurosurgery in small animals. This protocol allows trainees in neuroscience research to become familiar with the microsurgery setting and learn neurosurgery techniques, such as craniotomy drilling, dura mater removal, and electrode implantation. Egg model suitably mimics animal neurosurgery for the replacement and sparing of animals intended for training in neurosurgical skills.

Use of deep brain stimulation for major affective disorders.

The multifactorial etiology of major affective disorders, such as major depression and bipolar disorder, poses a challenge for identification of effective treatments. In a substantial number of patients, psychopharmacologic treatment does not lead to effective continuous symptom relief. The use of deep brain stimulation (DBS) for treatment-resistant patients is an investigational approach that has recently produced promising results. The recent development of safer stereotaxic neurosurgery, and the combination with functional neuroimaging to map the affected brain circuits, have led to the investigation of DBS as a potential strategy to treat major mood disorders. Several independent clinical studies have recently shown that chronic DBS treatment leads to remission of symptoms in a high number of treatment-resistant patients for major depression and bipolar disorder. In conclusion, the existing proof-of-principle that DBS can be an effective intervention for treatment-resistant depression opens new avenues for treatment. However, multicenter, randomized and blind trials need to confirm efficacy and be approved after the most recent failures. Patient selection and surgical-related improvements are key issues that remain to be addressed to help deliver more precise and customized treatment.

Ratat1: A Digital Rat Brain Stereotaxic Atlas Derived from High-Resolution MRI Images Scanned in Three Dimensions.

A digital rat brain atlas, in PDF format, was derived from high-resolution in situ magnetic resonance images (MRI). The images depict transverse, sagittal, and horizontal views in contiguous 0.2 mm slices, with a planar resolution of 50 µm. Each slice was indexed to the skull surface as well as the skull landmarks Bregma and Lambda. Using a common interactive file format enables users to customize the images for their application, including image reproduction with or without background or labels. The objective was to provide an open access supplementary guide for stereotaxic neurosurgery that permits more accurate visualization of targets and determination of target coordinates in Long Evans rats. A secondary objective was to present the atlas in the widely used PDF format, not requiring specialized software for viewing, copying or unpacking. A compressed version of the atlas is available as a supplement, while an uncompressed version is available at: https://figshare.com/articles/RatAtlas_2_0_Locked_pdf/3144955.

Functional and Stereotaxic Neurosurgery: Concepts of general interest

Es un libro breve pero muy actualizado sobre los principios de la neurocirugía funcional y estereotáctica. Dividido en 9 capítulos, comienza con una breve reseña histórica de la especialidad en Uruguay, país de nacimiento del autor. Continúa con los conceptos generales sobre neurocirugía funcional y estereotaxia, cirugía de los movimientos anormales, cirugía de los trastornos psiquiátricos, cirugía de la espasticidad, tratamiento neuroquirúrgico del dolor, cirugía de epilepsia, conceptos de radiocirugía y, finalmente, anestesia en neurocirugía funcional y estereotáctica. El autor, Dr. Humberto Prinzo, es un joven y reconocido neurocirujano uruguayo, quien contó con la colaboración de 13 autores nacionales, con sólida formación y experiencia en la temática abordada.

From passive tool holders to microsurgeons: safer, smaller, smarter surgical robots.

Within only a few decades from its initial introduction, the field of surgical robotics has evolved into a dynamic and rapidly growing research area with increasing clinical uptake worldwide. Initially introduced for stereotaxic neurosurgery, surgical robots are now involved in an increasing number of procedures, demonstrating their practical clinical potential while propelling further advances in surgical innovations. Emerging platforms are also able to perform complex interventions through only a single-entry incision, and navigate through natural anatomical pathways in a tethered or wireless fashion. New devices facilitate superhuman dexterity and enable the performance of surgical steps that are otherwise impossible. They also allow seamless integration of microimaging techniques at the cellular level, significantly expanding the capabilities of surgeons. This paper provides an overview of the significant achievements in surgical robotics and identifies the current trends and future research directions of the field in making surgical robots safer, smaller, and smarter.

Technique Offers Hope for Treatment-Resistant Depression

Technique Offers Hope for Treatment-Resistant Depression

Basic Surgical Techniques in the Göttingen Minipig: Intubation, Bladder Catheterization, Femoral Vessel Catheterization, and Transcardial Perfusion

The emergence of the Göttingen minipig in research of topics such as neuroscience, toxicology, diabetes, obesity, and experimental surgery reflects the close resemblance of these animals to human anatomy and physiology 1-6.The size of the Göttingen minipig permits the use of surgical equipment and advanced imaging modalities similar to those used in humans 6-8. The aim of this instructional video is to increase the awareness on the value of minipigs in biomedical research, by demonstrating how to perform tracheal intubation, transurethral bladder catheterization, femoral artery and vein catheterization, as well as transcardial perfusion. Endotracheal Intubation should be performed whenever a minipig undergoes general anesthesia, because it maintains a patent airway, permits assisted ventilation and protects the airways from aspirates. Transurethral bladder catheterization can provide useful information about about hydration state as well as renal and cardiovascular function during long surgical procedures. Furthermore, urinary catheterization can prevent contamination of delicate medico-technical equipment and painful bladder extension which may harm the animal and unnecessarily influence the experiment due to increased vagal tone and altered physiological parameters. Arterial and venous catheterization is useful for obtaining repeated blood samples and monitoring various physiological parameters. Catheterization of femoral vessels is preferable to catheterization of the neck vessels for ease of access, when performing experiments involving frame-based stereotaxic neurosurgery and brain imaging. When performing vessel catheterization in survival studies, strict aseptic technique must be employed to avoid infections6. Transcardial perfusion is the most effective fixation method, and yields preeminent results when preparing minipig organs for histology and histochemistry2,9. For more information about anesthesia, surgery and experimental techniques in swine in general we refer to Swindle 2007. Supplementary information about premedication and induction of anesthesia, assisted ventilation, analgesia, pre- and postoperative care of Göttingen minipigs are available via the internet at http://www.minipigs.com10. For extensive information about porcine anatomy we refer to Nickel et al. Vol. 1-511.

Development of a thulium (Tm:YAP) laser system for brain tissue ablation

In this study, a thulium (Tm:YAP) laser system was developed for brain surgery applications. As the Tm:YAP laser is a continuous-wave laser delivered via silica fibers, it would have great potential for stereotaxic neurosurgery with highest local absorption in the IR region. The laser system developed in this study allowed the user to set the power level, exposure time, and modulation parameters (pulse width and on-off cycles). The Tm:YAP laser beam (200-600 mW, 69-208 W/cm(2)) was delivered from a distance of 2 mm to cortical and subcortical regions of ex-vivo Wistar rat brain tissue samples via a 200-μm-core optical fiber. The system performance, dosimetry study, and ablation characteristics of the Tm:YAP laser were tested at different power levels by maximizing the therapeutic effects and minimizing unwanted thermal side-effects. The coagulation and ablation diameters were measured under microscope. The maximum ablation efficiency (100 × ablation diameter/coagulation diameter) was obtained when the Tm:YAP laser system was operated at 200 mW for 10 s. At this laser dose, the ablation efficiency was found to be 71.4% and 58.7% for cortical and subcortical regions, respectively. The fiber-coupled Tm:YAP laser system in hence proposed for the delivery of photothermal therapies in medical applications.

Hemiballism due to an ipsilateral subthalamic nucleus lesion

An 87-year-old right-handed man with untreated hypertension and hypercholesterolaemia presented with acute flinging and throwing movements of the left upper and lower limb. Clinical examination confirmed involuntary, irregular, wide amplitude movements of the left limbs consistent with left hemiballism in the absence of other neurological deficit. Blood count, CRP, glucose level, calcium, renal and liver function tests, ANF, lupus anticoagulant, anticardiolipin antibodies, thyroid function, serology of HIV, and arterial blood gas analysis were all normal. Brain MRI showed an acute infarction in the left (i.e. ipsilateral to the hemiballistic movements) subthalamic nucleus (STN) zone (Fig. 1), together with signs of chronic ischaemic microangiopathy in the brainstem and the periventricular areas (Fig. 2). [F] FDG PET performed 1 week after symptom onset revealed hypometabolism in the left hemispheric cortex (preserving only the anteromedial part of the frontal lobe) and the left caudate nucleus and the putamen (Fig. 1), probably due to deafferentation via connections between the STN and the ipsilateral basal ganglia system and the cortex, respectively. Carotid duplex sonography showed bilateral nonstenotic carotid atheroma. Electrocardiography and transthoracic echocardiography were normal. Recent infarction was probably due to occlusion of a small artery related to untreated cardiovascular risk factors. Secondary prevention treatment for ischaemic stroke was started. Neuropsychological testing 1 week after symptom onset showed a mild to moderate amnestic syndrome with preserved executive functions. Hemiballism disappeared progressively over the following months. [F] FDG PET 5 months after hemiballism onset showed near complete recovery of hypometabolism (Fig. 1), and neuropsychological testing normalized. Historically, acute hemiballism was thought to be related almost exclusively to contralateral (ischaemic or haemorrhagic) STN lesions. However, recently the era of modern neuroimaging has allowed identification of lesions often outside the STN (e.g. thalamus, globus pallidum, putamen, caudate nucleus, white matter, and cortex) [1]. The vast majority of lesions are contralateral to the hemiballism. Only a few cases with ipsilateral STN lesions have been described [2, 3]. The pathophysiology of ipsilateral hemiballism is poorly understood. The possibility that the STN exerts a bilateral control of motor function may explain this. This is supported by the observation that unilateral stereotaxic neurosurgery in Parkinson’s disease frequently results in bilateral improvement of abnormal movements. Anatomic pathways related to this bilateral control are unknown. [F] FDG PET in our patient nicely showed the connections between the STN and the other ipsilateral brain structures. DimitriRenard (&) A. Le Floch G. Castelnovo P. Labauge Department of Neurology, CHU Nimes, Hopital Caremeau, Place du Pr Debre, 30029 Nimes Cedex 4, France e-mail: dimitrirenard@hotmail.com

Effect of deep brain stimulation of the subthalamic nucleus upon the contralateral subthalamic nucleus in Parkinson disease

High frequency stimulation (HFS) of the subthalamic nucleus (STN) is an effective treatment of idiopathic Parkinson disease (PD). Exactly how HFS works remains unclear. Although HFS of the STN is most effective in improving contralateral motor functions, clinical studies have shown bilateral beneficial effects suggesting that unilateral STN HFS affects both ipsilateral and contralateral basal ganglia networks. In this study we evaluated the effect of STN HFS upon the contralateral STN in 14 PD subjects. The neural recordings were done during stereotaxic neurosurgery for implantation of deep brain stimulation electrodes in the second STN. Neuronal activity of the STN was analyzed before and during two minutes of HFS. There was a significant increase in the multiunit spiking activity of the STN during HFS in the contralateral STN. Our study provides direct electrophysiological evidence that the STN HFS is associated with increased activity of the contralateral STN. These findings suggest that increased STN output underlies therapeutic mechanisms of action of HFS.

Chloral Hydrate Is Not Acceptable for Anesthesia or Euthanasia of Small Animals

We sincerely thank Baxter et al . for their interests in our article and their valuable information about the use of chloral hydrate for rats' anesthesia and euthanasia in our experiment.First, we would like to emphasize that we do not think the reliability of our experimental results was influenced by chloral hydrate. Chloral hydrate was used in all the experimental groups, thus its interpretations were comparable among these groups. Our significant findings could not be simply induced by it. In addition, the mechanisms of most anesthetics, including their effects on Arc expression, are still obscure. Furthermore, sevoflurane has even been proved to inhibit Arc transcription.1Under this condition, choosing any other anesthetic for rat euthanasia may produce the similar unpredicted interpretations. Therefore, we believe that to a great extent, our results and conclusions are reliable.Second, we designed our experiment on the basis of a great deal of published articles on authority journals. The method as intraperitoneal injection of chloral hydrate was wildly used to rats for some kinds of surgeries, particularly with the word as “anesthesia.” For example, Rodríguez Manzanares et al ., Bredeloux et al ., and Sammut et al . all use chloral hydrate to anesthetize rats for stereotaxic neurosurgery to implant cannulae.2–4Actually, in recent years, chloral hydrate is still widely used to anesthetize rats. However, we agree with the view of Baxter et al . that some other anesthetics (like Phenobarbital sodium) may be more suitable in this type of surgery because of the side effects of chloral hydrate illustrated by them. Fortunately, the overwhelming majority of rats in our experiment recovered well from the neurosurgery, with normal appetite and defecation.Third, we admit that we neglect the potential problem of using chloral hydrate for euthanasia of rats. Chloral hydrate is a traditional anesthetic in animal experiments, and before we performed our study we also found that it is used for killing rats by either decapitation or cardiac perfusion in respectable published articles.2,5,6Moreover, our research was approved by the Institutional Animal Care and Use Committee with no questions. Therefore, we never doubted the use of chloral hydrate for rat euthanasia. Now we feel deeply sorry for the possibility of inflicting pain on the animals because of using chloral hydrate.Finally, we would like to extend our sincere gratitude to Baxter et al . for letting us understand animal euthanasia more deeply. We will pay much more attention to the euthanasia issue, adopt proper and scientific animal welfare methods, and try our best to decrease harm to the experimental animals as much as possible in future research.*Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, People's Republic of China. yubuwei@yahoo.com.cn

The importance of angiotensin II in mediating cognitive processes and neuronal oxidative stress status

Event Abstract Back to Event The importance of angiotensin II in mediating cognitive processes and neuronal oxidative stress status Alin Ciobica1*, Walther Bild1, Lucian Hrticu1 and Ioan Haulica1 1 Romanian Academy, Romania In addition to its well known central actions, brain angiotensin II (Ang II) possesses interesting cognitive properties. Both stimulatory and inhibitory effects of Ang II on memory functions have been reported. There is also evidence that oxidative stress accompanies angiotensin II infusion, but the role of AT 1 vs. AT 2 receptors on the generation of reactive oxygen species is not clear.Losartan (AT 1 antagonist), PD 123177 (AT 2 antagonist), captopril (angiotensin converting enzyme-ACE inhibitor) and Ang II were administered by stereotaxic neurosurgery in the left cerebral ventricle. Passive avoidance and Y maze tasks were used for memory assessment. We also assessed the levels of some enzymatic antioxidant defences like superoxid dismutase (SOD) and glutathione peroxidase (GPX), as well as lipid oxidation makers like MDA (malondialdehyde), from the temporal lobe, using chemiluminometric and spectrophotometric methods.In Y maze and the passive avoidance tasks the administration of losartan, PD 123177 and captopril resulted in an increase of memory functions. The administration of angiotensin II induced a significant memory decrease in both spontaneous alternation and step-through-latency.Alterations in the specific activity of the antioxidant enzymes (SOD and GPX) were found in the temporal lobe of angiotensin II treated rats, while the administration of losartan, PD 123177 and captopril resulted in an increase of these enzymes activity, compared to sham-operated group. Also the levels of MDA were found increase in angiotensin II treated rats.This study clearly demonstrates that inhibition of the RAS (renin-angiotensin system) with either an ACE inhibitor or AT1/AT 2 blockers induces a significant facilitator effect on the cognitive functions and a substantial reduction in neuronal oxidative stress status. Therefore, the use of antihypertensive drugs may be associated with a lower rate of cognitive decline. Conference: 41st European Brain and Behaviour Society Meeting, Rhodes Island, Greece, 13 Sep - 18 Sep, 2009. Presentation Type: Poster Presentation Topic: Poster presentations Citation: Ciobica A, Bild W, Hrticu L and Haulica I (2009). The importance of angiotensin II in mediating cognitive processes and neuronal oxidative stress status. Conference Abstract: 41st European Brain and Behaviour Society Meeting. doi: 10.3389/conf.neuro.08.2009.09.117 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 08 Jun 2009; Published Online: 08 Jun 2009. * Correspondence: Alin Ciobica, Romanian Academy, Iasi, Romania, alinmimi@yahoo.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Alin Ciobica Walther Bild Lucian Hrticu Ioan Haulica Google Alin Ciobica Walther Bild Lucian Hrticu Ioan Haulica Google Scholar Alin Ciobica Walther Bild Lucian Hrticu Ioan Haulica PubMed Alin Ciobica Walther Bild Lucian Hrticu Ioan Haulica Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

MicroTargeting® platform: an individual stereotaxic device in functional neurosurgery

Object: Deep brain stimulation of the Nucleus subthalamicus (DBS-STN) results in an improvement of cardinal symptoms of Parkinson disease (PD) and allows a significant reduction of medication. Because of the potential risk of inaccuracies during image acquisition, planning procedure, placement of test electrodes and final electrode insertion a microTargeting® platform, FHC Company, Germany, as an example of automation in stereotaxic neurosurgery was used.

Dropped head in Parkinson’s disease

"A propensity to bend the trunk forward" and "the chin is now almost immovably bent down upon the sternum" were described by James Parkinson in patients with Parkinson's disease (PD). The term "dropped head" was first reported in "Gerlier disease" in Switzerland and 'kubisagari' in Japan and since then also reported in myositis, myopathy, myasthenia gravis, amyotrophic lateral sclerosis, neuropathy, and hypothyroidism. Disproportionate antecollis occurs in about half cases of multiple system atrophy (MSA) and is considered dystonic in nature. Dropped head is considered rare in PD, both in advanced and early stages of PD. However, it is known to progress subacutely over a period of several days. In my experience, dropped head is relatively common in PD. The mechanism of dropped head in PD is either dystonia of flexor neck muscles or weakness of extensor neck muscles. The response of dropped head to various anti-parkinsonian medications is rather inconsistent. Levodopa is reported to induce amelioration in some patients while dopamine agonists can cause deterioration. Muscle afferent block with lidocaine and ethanol is reported to be effective, while the effect of botulinum toxin injection into the affected muscles is limited. The effect of stereotaxic neurosurgery on dropped head is controversial. Early diagnosis and prompt treatment is necessary to prevent muscle damage associated with longterm overstretch of extensor neck muscles.

PET imaging of the basal ganglia

The present chapter reviews PET imaging in basal ganglia disorders; Parkinson’s disease is used as a model of these disorders because the neurochemical pathobiology of this disease is well known and great advances in the imaging area have been achieved. Other basal ganglia disorders including Tourette’s syndrome, dystonia, Huntington’s chorea and Wilson’s disease are also dealt with. With PET and SPECT techniques, the whole integrative dopaminergic network of neurons can be studied, which plays an important role in differential diagnostics. Furthermore, pharmacological effects of medication can be visualized and the role of stereotaxic neurosurgery can be evaluated. Finally, functional imaging gives clues about the prognosis and rehabilitation aspects of the basal ganglia disorders.