Leksell's posteroventral pallidotomy in the treatment of Parkinson's disease

Pallidotomy increases activity of motor association cortex in Parkinson's disease: a positron emission tomographic study

Stereotactic posteroventral pallidotomy can improve motor performance in Parkinson's disease. Interruption of inhibitory pallidal projections to ventrolateral thalamus, components of a cortical-basal ganglia motor loop allows for this clinical benefit. We hypothesized that pallidotomy would lead to increased movement related activity in motor cortical areas receiving projections from ventrolateral thalamus. This was tested in 6 Parkinson's disease patients who underwent stereotactic posteroventral pallidotomy. Each patient was imaged with positron emission tomography (PET) measures of regional cerebral blood flow (rCBF) during performance of a simple prehension task and at rest. Scans were acquired before and 17 weeks after surgery. After pallidotomy, movement-related changes of rCBF increased significantly in both the supplementary motor area (SMA) and premotor cortex but not in primary motor cortex. The results demonstrate the importance of pallidothalamic circuitry for regulating volitional movements and confirm that disruption of inhibitory input to the ventrolateral thalamus can augment movement-related activity in motor association areas.

Ventroposterior medial pallidotomy in patients with advanced Parkinson's disease

In a preliminary study, the effects of ventroposterior medial pallidotomy were evaluated in five patients with advanced Parkinson's disease in whom medical therapy had failed. The mean age was 67.0 +/- 5.6 years, and the mean Hoehn and Yahr stage when "off" was 3.9 +/- 1.3. Three patients received unilateral pallidotomies; two of these received another pallidotomy after 8 weeks. Two other patients received staged bilateral pallidotomies. No significant differences in overall function could be seen before and after the first surgical procedure. All three patients with peak-dose dyskinesias or dystonia had marked contralateral reduction in these symptoms. Ventroposterior medial pallidotomy can ameliorate peak-dose dyskinesias in patients with advanced Parkinson's disease. Overall function improvement is not remarkable.

The results, indications, and physiology of posteroventral pallidotomy for patients with Parkinson's disease

In the past, stereotactic surgical intervention for Parkinson's disease was considered indicated only in those patients with active motor manifestations that were refractory to pharmacological therapy, manifestations such as tremor, rigidity, dystonia, and dyskinesia. With the reintroduction and refinement of Leksell's posteroventral pallidotomy, both akinetic and hyperkinetic symptoms are now amenable to surgical treatment. We have analyzed the results of 126 patients who underwent either unilateral (n = 58) or bilateral (n = 68) posteroventral pallidotomies. The Unified Parkinson's Disease Rating Scale and Hoehn and Yahr Staging Scale were used for preoperative and postoperative objective assessments. Postoperative follow-up evaluation occurred initially at 1 week and subsequently at intervals between 1 and 12 months (mean = 4.5 months) after surgery. Although individual motor subscores on the Unified Parkinson's Disease Rating Scale were significantly reduced (n = 126, P < or = 0.01), the most dramatic findings were the reversal of akinetic symptoms and the elimination of dyskinesia and profound "off" periods. These clinical results, combined with intraoperative microelectrode records revealing pallidal neuronal hyperactivity, suggest a reconsideration of the pathophysiology of akinesia and point to possible mechanisms of akinesia improvement by posteroventral pallidotomy in some parkinsonian subgroups.

Preproenkephalin and preprotachykinin messenger RNA expression in normal human basal ganglia and in Parkinson's disease

Striatal expression of preproenkephalin and preprotachykinin messenger RNA was studied in normal controls and in patients with Parkinson's disease using in situ hybridization histochemistry. In controls, preproenkephalin messenger RNA was expressed in a population of medium-sized neurons of mean cross-sectional area 165 microns 2, accounting for 66% of striatal medium-sized neurons, whereas preprotachykinin messenger RNA was expressed in a population of medium-sized neurons of mean cross-sectional area 204 microns 2 (23% larger than those expressing enkephalin, P < 0.05), accounting for 58% of medium-sized striatal neurons. Much lower levels of both preproenkephalin messenger RNA and preprotachykinin messenger RNA were expressed by large neurons in the globus pallidus and substantia nigra reticulata. In addition, preproenkephalin messenger RNA was expressed at low levels by neurons in the subthalamic nucleus. In Parkinson's disease cases, there was a statistically significant increase in preproenkephalin messenger RNA expression in the body of the caudate (109% increase, P < 0.05) and in the intermediolateral putamen (55% increase, P < 0.05) due to an increase in the level of gene expression per neuron rather than an increase in the number of neurons expressing preproenkephalin messenger RNA. Similar increases were observed in other putaminal subregions and in the putamen as a whole, but these did not reach statistical significance. No change in preprotachykinin messenger RNA expression was detected. These findings demonstrate selective up-regulation of a striatal neuropeptide system in Parkinson's disease compatible with increased activity of the "indirect" striatopallidal pathway, which is thought to play a crucial role in the pathophysiology of akinesia and rigidity in this condition.

Chronic anterior pallidal stimulation for Parkinson's disease

We present the case of a 51-year-old female who had a four-year history of Parkinson's disease with severe "on-off' and disabling progression of symptoms on chronic levodopa therapy. After obtaining FDA approval, we implanted a Medtronic deep brain stimulation lead stereotactically into the right anterior pallidum contralateral to her most symptomatologic side. Intra-operative stimulation trials at 100 Hz caused reproducible reversal of akinetic symptoms and simultaneous microelectrode recording of the posteroventral pallidum revealed decreased neural activity during anterior pallidal stimulation. The patient was evaluated pre-operatively and postoperatively using the Hoehn and Yahr Staging Scale, the Unified Parkinson's Disease Rating Scale (UPDRS), videotape, and a computerized data glove. Six months after implantation, the total UPDRS score was decreased from 68 to 8 and Hoehn and Yahr Staging improved from 3.0 to 1.5 during periods of chronic high frequency stimulation. Dramatic improvements in tremor, dystonia, bradykinesia, and akinesia were noted within seconds of stimulator activation and were also objectively measured using a computerized data glove. This case reveals the potential for therapeutic pallidal stimulation for Parkinson's akinetic symptomatology.

Crucial role of the accumbens nucleus in the neurotransmitter interactions regulating motor control in mice

Previous work, based on systemic drug administration, has shown that neurotransmitter interactions between dopaminergic, adrenergic, glutamatergic and cholinergic systems are involved in locomotor control in mice. In an attempt to identify the target sites in the brain of these interactions, we have started a series of experiments, where the drugs are administered intracerebrally in mice. The locomotor threshold doses of the competitive NMDA antagonist AP-5 and the noncompetitive NMDA antagonist MK-801 were investigated by means of local application in the accumbens nucleus of monoamine-depleted and monoaminergically intact mice, respectively. The threshold dose of AP-5 was lower in depleted than in intact animals, whereas the threshold dose of MK-801 was lower in monoaminergically intact than monoamine-depleted mice. The locomotor effects of AP-5 and the AMPA-kainate receptor antagonist CNQX were registered in monamine-depleted mice after local application in the accumbens or entopeduncular nucleus (= medial pallidum). Both AP-5 and CNQX stimulated locomotor activity in the accumbens, but had no effects in the entopeduncular nucleus. We have previously shown synergistic interactions with regard to locomotor stimulation in monoamine-depleted mice, between an NMDA antagonist and an alpha 2-adrenoceptor agonist or a dopamine D1 agonist (all drugs given systemically). In the present study the alpha 2-adrenoceptor agonist alpha-methylnoradrenaline was applied intracerebrally in combination with a subthreshold dose of MK-801 given intraperitoneally: Locomotor stimulation was produced after alpha-methyl-noradrenaline injection into the accumbens nucleus, but not after injection into the dorsal striatum, prefrontal cortex or thalamus. Likewise, local application of the D1 agonist SKF 38393, in combination with a subthreshold dose of MK-801 given intraperitoneally, point to an important role of the accumbens nucleus in motor control. Previous experiments based on systemic drug administration have also shown a synergistic interaction between a muscarine antagonist and an alpha 2-adrenoceptor agonist in monoamine-depleted mice. Local application of the muscarine antagonist methscopolamine, in combination with the alpha 2-adrenoceptor agonist clonidine given intraperitoneally, showed that the striatum, in this case both the ventral and dorsal parts of the striatum, is an important target for the muscarine antagonist. Unilateral injection of AP-5 into the accumbens nucleus of mice induces rotational behaviour: Previous findings have shown that the rotation is ipsilateral in monoaminergically intact animals, whereas monoamine-depleted animals rotate contralaterally. In addition, these findings have shown that dopamine D2 receptor stimulation seems to determine whether AP-5 will induce ipsilateral or contralateral rotation. In the present study we report further evidence for a crucial role of the D2 receptor in this respect. Finally, the rotational effects of AP-5 injected into the dorsal striatum or hippocampus were investigated: As after AP-5 application into the accumbens nucleus, monoaminergically intact mice rotated ipsilaterally, whereas monoamine-depleted animals rotated contralaterally, following AP-5 application in the dorsal striatum or the hippocampus. The present data show that the accumbens nucleus has an important role in motor control. Both glutamatergic, muscarine cholinergic, dopaminergic and alpha-adrenergic systems are involved in the control of motor functions in the accumbens nucleus.

Effect of parkinsonian signs and symptoms of bilateral subthalamic nucleus stimulation

In monkeys rendered parkinsonian, lesions and electrical stimulation of the subthalamic nucleus reduce all major motor disturbances. The effect of electrical stimulation of the subthalamic nucleus was assessed in three patients with disabling akinetic-rigid Parkinson's disease and severe motor fluctuations. Quadripolar electrodes connected to a pulse generator were implanted in the subthalamic nuclei on both sides. Patients were evaluated with the unified Parkinson's disease rating scale and timed motor tests. 3 months after surgery, activities of daily living scores had improved by 58-88% and motor scores by 42-84%. This improvement was maintained for up to 8 months in the first patient operated upon. One patient was confused for 2 weeks after surgery, and another developed neuropsychological impairment related to a thalamic infarction which improved over 3 months. In one patient, stimulation could induce ballism that was stopped by reduction of stimulation. This is the first demonstration in human beings of the part played by the subthalamic nuclei in the pathophysiology of Parkinson's disease.

Functional anatomy of the basal ganglia. II. The place of subthalamic nucleus and external pallidum in basal ganglia circuitry

The subthalamic nucleus and the external pallidum (GPe) are classically viewed as part of the so-called indirect pathway, which acts in concert with the direct pathway. The direct and indirect pathways form the conceptual framework of the anatomical and functional organization of the basal ganglia. A review of recent data regarding the connections of the subthalamic nucleus and the GPe has revealed a lack of firm anatomical support for the existence of the indirect pathway. However, newly recognized projections of the subthalamic nucleus and the GPe place these structures on various novel routes that change the conceptual architecture of the basal ganglia circuitry. These new findings force us to modify our view of the functional identity of the subthalamic nucleus and the GPe. In this new perspective, the GPe stands as an additional integrative station, together with the striatum and the internal pallidum and substantia nigra pars reticulata (GPi/SNr), along the main steam of information processing within the basal ganglia circuitry. Because of its crucial position between the input and output stations of the basal ganglia, the GPe can markedly influence the neuronal computation that occurs at GPi/SNr levels. The subthalamic nucleus can still be regarded as a 'control structure' lying alongside the main stream of information processing. However, because of its widespread efferent projections, the subthalamic nucleus exerts its driving effect on most components of the basal ganglia. Its action is mediated not only by the indirect pathway, but by a multitude of mono- and polysynaptic projections that ultimately reach the basal ganglia output cells.

The role of the basal ganglia in motor control: contributions from PET

This article reviews PET activation data on basal ganglia function that have been reported in association with performance of different motor tasks by normal subjects and movement disorder patients. PET findings are contrasted with electrophysiological observations both in man and in non-human primates and with observations on clinical and cognitive function of movement disorder patients. Possible roles that the basal ganglia may play in motor control are discussed in the light of these data.

Anatomic and physiological considerations in pallidotomy for Parkinson's disease

Our ongoing study of ventral pallidotomy for the control of Parkinson's disease in selected patients has provided the opportunity to explore the topographical and somatotopic organization of the human globus pallidus. Utilizing microelectrode techniques we have obtained recordings which were correlated with data from MPTP-parkinsonian primates. In addition, we performed pre- and post-operative FDG/PET scans in these patients. Our studies reveal similarities between the MPTP-parkinsonian primate model and human Parkinson's disease in terms of physiologic recordings and responses. However, we have encountered significant differences between dominant and non-dominant hemisphere representations, particularly for the hand, in the human. In addition, our PET studies confirmed, as in previous parkinsonian primate models, glucose hypermetabolism in the lenticular area of Parkinson's disease patients. This hypermetabolism is dramatically altered by creation of a lesion in the globus pallidus medialis. This is demonstrated by follow-up PET scans which reveal not only a decrease in metabolism of the operated lenticular region, but also in the frontal cortical projections. These combined observations of the cellular activity in the globus pallidus and the observed changes in PET metabolism support the selection of the pallidum for lesioning and control of Parkinson's disease, and offer insight into the underlying physiology of this disorder. The above physiological and PET data will be clinically correlated with our ongoing series of 35+ patients.

Microelectrode monitoring of cortical and subcortical structures during stereotactic surgery

We describe microelectrode recording and stimulation techniques to delineate the cellular boundaries and neural projections of stereotactic brain targets. These techniques have applications in the surgery for pain, movement disorders and in psychosurgery. Neuronal records from stereotactic operations including thalamotomy, pallidotomy, cingulotomy and anterior capsulotomy are discussed. These tools are used to distinguish gray matter from white matter, to obtain direct measures of cellular activity in the target, to identify the physiological properties and receptive fields of the subpopulation of neurons at the electrode tip and to avoid lesion making induced injury to adjacent structures. Microelectrode recording and stimulation techniques improve physiological localization and decrease the possibility of unwanted neurological complications with functional stereotactic procedures.

Bilateral chronic electrostimulation of ventroposterolateral pallidum: a new therapeutic approach for alleviating all parkinsonian symptoms

The global improvement of all parkinsonian symptoms after stereotactic pallidotomy has been demonstrated by Leksell. Recently, Laitinen, re-evaluating this target in the neurosurgical treatment of Parkinson's disease, confirmed the real value of this approach, and emphasized the necessity of locating the lesion in the ventroposterolateral part of the pallidum internum. Because we know that high-frequency stimulation of the ventrolateral part of the thalamus has the same clinical effect on tremor as high-frequency coagulation, this technique has now been applied bilaterally in one session in three patients who have severe Parkinson's disease, with akinesia and levodopa-induced dyskinesias in the foreground. The very satisfactory clinical results, up to 12 months in the first case, confirm the observation of Laitinen, but with the difference that the approach discussed here is both nondestructive and reversible, and unwanted side effects are avoided.

Human neural transplantation

Great advances in neurobiology have resulted from 100 years of neural transplantation research. In the last 20 years, there has been a focus on using neural transplantation to repair the damaged central nervous system (CNS) utilising experimental animal models of various human neurodegenerative disease and CNS injury. Since 1985, there has been a rapid proliferation of adrenal medullary autograft transplantation to the caudate nucleus of humans with Parkinson's disease. However, this operation proved to be unsuccessful and was associated with unacceptable morbidity. Implantation of human fetal mesencephalon into patients with severe parkinsonism has supplanted the adrenal operation and has produced promising results, with some patients reported to improve markedly and some evidence of graft survival noted on positron emission tomography (PET). Host tissue recovery appears to be an important mechanism for this clinical improvement. The optimal technique is to use three to four fetuses from induced abortions of 6.5 to 8 weeks gestation, with multiple stereotactic implants into the putamen and caudate nucleus. Many biological questions still remain and the community remains troubled by the ethical problems of using fetal tissue obtained from abortions. This procedure is still experimental and should be restricted to a few centres with excellence in cell and molecular biology. A multicentre study is needed to more carefully evaluate CNS transplantation. Cloned neural precursor cells or immortalized embryonic cell lines genetically modified to manufacture selected growth factors or neurotransmitters may offer an alternative to the use of human fetal tissue. Much more experimental animal research is necessary before transplantation can be used to treat other CNS maladies.

Contemporaneous bilateral postero-ventral pallidotomy for early onset "juvenile type" Parkinson's disease. Case report

Early onset "juvenile type" Parkinson's disease is commonly associated with disabling bilateral levodopa-induced dyskinesias. We report here a successful contemporaneous bilateral postero-ventral pallidotomy performed on a 46-year-old male with juvenile type Parkinson's and associated levodopa incited symmetric dyskinesias. A comparison of various surgical alternatives is included. Preoperative and postoperative evaluation, operative method and posteroventral pallidotomy's therapeutic mechanism are presented.

Behavioral assessment of the ability of intracerebral embryonic neural tissue grafts to ameliorate the effects of brain damage in marmosets

The transplantation of neuronal tissue into the brains of patients with Parkinson's disease is already being assessed as an experimental treatment for the symptoms of this disease, and the possibility of using similar graft tissue to ameliorate the symptoms of other neurodegenerative diseases is being considered. In this context, a small number of transplant experiments have been carried out in monkeys with lesions of the central dopamine and cholinergic systems. These experiments make it possible to determine the optimum methods of transplantation in an animal whose brain is structurally more closely related to the human than that of the rat and to assess the behavioral consequences of transplantation on symptoms that either resemble very closely the symptoms seen in patients, or are of a complex cognitive nature and are therefore more difficult to measure in the rat. It is intended that these experiments will contribute to the development of better treatments for the neurodegenerative diseases, either by the use of transplantation as a clinical treatment, or by contributing to a better understanding of the mechanisms that normally maintain neuronal function and that fail in these diseases.

Excitotoxic lateral pallidotomy does not relieve L-dopa-induced dyskinesia in MPTP parkinsonian monkeys

We attempted to relieve the marked overactivity known to occur in the lateral segment of the globus pallidus (GPL) in L-DOPA-induced dyskinesia (LID) by unilateral stereotaxic ibotenic acid lesioning of the GPL in 4 monkeys with MPTP-induced parkinsonism. Two already dyskinetic animals were pallidotomized to counteract LID once established, while 2 L-DOPA-naive MPTP-treated animals were pallidotomized before L-DOPA was ever administered in an attempt to prevent the development of the process conductive to LID. Acutely after the lesion, more prominent akinesia (particularly in the contralateral limbs) with contraversive body deviation and circling behavior were seen for 48 h. Flexor posturing of the contralateral forelimb persisted to a variable degree. When L-DOPA treatment was resumed or instituted 1 week postoperatively, ipsiversive circling behavior occurred in all animals and contralateral dyskinesia worsened in 3, whether L-DOPA or a selective dopamine D2 agonist was administered. Lesions in these 3 cases were fairly restricted to the GPL histologically. One monkey kept L-DOPA-naive before pallidotomy never developed LID contralaterally to the lesion despite treatment for several months. The lesion this time involved the entire GP. The fact that ablation of the GPL worsened LID suggests that a complex rearrangement of the balance of functional capacity between the GP and the subthalamic nucleus takes place in LID which is not amenable to correction merely by a lateral pallidotomy. Our observations also suggest that functional redundancy exists in striatopallidal circuits and that no single pathway is responsible for LID.

Neurophysiological properties of pallidal neurons in Parkinson's disease

Neuronal properties of the human globus pallidus (GP) are not known. Since GP is the major output of the basal ganglia, it may be involved in the pathophysiology of Parkinson's disease. We studied 12 patients with medically resistant Parkinson's disease by using single cell recording of the GP during stereotaxic pallidotomy to define neuronal firing rate and its modulation during active and passive movements. Different frequency and pattern of single cell activity was found in globus pallidus externus compared with globus pallidus internus. Discharge rates of 19% of GP cells were modulated by passive contralateral movements. Pallidal units were most often related solely to single joint movement. Different patterns of activity in relation to the two different movements of the same joint were often observed. We identified somatotopically arranged cell clusters that alter discharge rate with related movements. These findings suggest at least a partial somatotopic organization of the human GP and similarity with experimental results in both healthy and MPTP monkeys, providing a rationale for surgical or pharmacological targeting of GP for treating Parkinson's disease.

The subthalamic nucleus: a possible target for stereotaxic surgery in Parkinson's disease

Hyperactivity in the subthalamic nucleus (STN) projections to the globus pallidus medialis (GPM) has been established as a crucial feature of parkinsonism in animal models of Parkinson's disease (PD). Recent experiments blocking the STN glutamatergic output to GPM or lesioning the STN support this concept by showing a dramatic reversal of parkinsonism. We review the role of stereotaxic surgery in the past and the possible future application of subthalamotomy for PD.

Rapid improvement of visuoperceptive functions by picoTesla range magnetic fields in patients with Parkinson's disease

Impairment in perceptual motor or visuospatial tasks is among the most frequently encountered abnormality in neuropsychological testing of patients with Parkinson's disease, being present in up to 90% of cases. Visuoperceptive deficits can result from cortical and subcortical lesions involving the right hemisphere, thalamus, and basal ganglia and are thought to reflect a defect in attentional-arousal mechanisms induced by lesions that interrupt a cortical-limbic-reticular activating loop. Clinically, the presence of visuoperceptive impairment may not be noted by Parkinsonian patients but may contribute to various disabilities including difficulty driving a vehicle and difficulties performing daily tasks which require intact visuospatial abilities (i.e., walking, dressing, drawing and copying designs). The present communication concerns two fully medicated Parkinsonian patients who responded to extracranial treatment with picoTesla range magnetic fields (MF), behaviorally and also demonstrated rapidly and dramatically enhanced visuoperceptive functions as demonstrated on various drawing tasks. These findings demonstrate the efficacy of extremely weak MF in enhancing cognitive functions in patients with Parkinson's disease.

Multiple output channels in the basal ganglia

The neural circuits that link the basal ganglia with the cerebral cortex are critically involved in the generation and control of voluntary movement. Retrograde transneuronal transport of herpes simplex virus type 1 was used to examine the organization of connections in the cebus monkey between an output nucleus of the basal ganglia, the internal segment of the globus pallidus (GPi), and three cortical areas: the primary motor cortex, the supplementary motor ara, and the ventral premotor area. Spatially separate regions of the GPi were labeled after virus injections into each cortical area. The GPi projects to multiple cortical motor areas, and this pallidal output is organized into discrete channels. This information provides a new anatomical framework for examining the function of the basal ganglia in skeletomotor control.