Intrastriatal Cografts of Autologous Adrenal Medulla and Sural Nerve in MPTP-Induced Parkinsonian Macaques: Behavioral and Anatomical Assessment

To examine the effects of autologous sural nerve and adrenal medullary tissue intrastriatal cografts upon voluntary motor performance in parkinsonism, a non-human primate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model was employed to quantitatively assess skilled hand movements. Motor performance was studied in normal, MPTP-induced parkinsonian, and then cografted states. Reaction and movement times were prolonged and variability increased in experimental and control animals in the parkinsonian state. Animals undergoing autologous cografts demonstrated improved motor performance whereas the control animal continued in a chronic, stable parkinsonian state. Intrastriatal cografts of autologous adrenal medullary tissue and sural nerve resulted in good to excellent chromaffin cell survival. The mechanism of the restoration of function in the cografted monkeys remains to be determined.

Polymer-Encapsulated PC-12 Cells Demonstrate High-Affinity Uptake of Dopamine in Vitro and 18F-DOPA Uptake and Metabolism after Intracerebral Implantation in Nonhuman Primates

Intracranial implantation of polymer-encapsulated PC-12 cells has been shown to improve motor behavioral performance in animal models of Parkinson's disease. The purpose of this blinded study was to examine whether such improvement is associated with the active uptake and metabolism of dopamine precursors by intracerebrally implanted polymer-encapsulated PC-12 cells. In an in vitro experiment we demonstrate that 3H-dopamine uptake by PC-12 cells was 108 fmol/min × 106 cells, and that this uptake can be specifically blocked 88% by the addition of 10 nM of nomifensine. In the in vivo experiments, polymer-encapsulated PC-12 cells were implanted in four MPTP-treated monkeys into the left deep parietal white matter (R1) or left striatum (R2-4). A fifth MPTP-treated monkey (R5) served as a control and received left striatal implants of empty capsules. 18F-Dopa Positron Emission Tomography (PET) imaging was performed on each monkey before and after implantation surgery by blinded investigators. PET images obtained 5-13 wk after implantation demonstrated well delineated focal areas of high 18F-dopa uptake in R1, R2, and R4. The focal area of high 18F-dopa uptake in R1 precisely coregistered on a brain magnetic resonance image to the site of implantation. R3 (in whom the polymer-encapsulated PC-12 cells demonstrated poor cell survival upon explantation) and R5 (empty capsules) failed to demonstrate any area of increased 18F-dopa uptake in their PET images. Histological examination of the host brain revealed no sprouting of dopaminergic nerve terminals around the implantation sites of the polymer-encapsulated PC-12 cells. These results indicate that the previously noted behavioral improvement after intrastriatal implantation of polymer encapsulated PC-12 cells is at least in part due to their highly specific uptake and metabolism of dopamine precursors. Furthermore, these data suggest that polymer-encapsulated PC-12 cells can store, reuptake, and functionally replenish dopamine and therefore, may be an effective treatment for Parkinson's disease.

Migration Patterns of Neonatal Subventricular Zone Progenitor Cells Transplanted into the Neonatal Striatum

Our previous studies have shown that the progeny of the neuronal progenitor cells localized in a discrete region of the anterior part of the neonatal subventricular zone, referred to as the SVZa, migrate tangentially along a stereotypical and extended pathway to the olfactory bulb, and then turn radially into one of the overlying cellular layers. In this study we have examined whether the SVZa cells retain their ability to migrate and disperse when heterotopically transplanted into the striatum. SVZa cells from P0–P2 rat pups were microdissected, dissociated, labeled with the lipophilic, fluorescent dye PKH26 or the cell proliferation marker BrdU, and then transplanted into the neonatal (P0–P2) striatum. Examination of the striatum a few days after transplantation revealed aggregates of heavily labeled BrdU-positive, SVZa cells in the striatum, often situated near blood vessels. Two to four weeks after transplantation, however, the labeled SVZa cells had disseminated from their site of implantation and showed three patterns of distribution. In none of the cases was the implantation site detectable in the striatum, signifying that the cells had become incorporated in the host brain. Of the 12 brains analyzed for cell distribution, transplanted SVZa cells were confined to the striatum in 4 cases. The cells were present as individual cells or in small groups of usually two to four cells. When PKH26 was used, we found that many of the transplanted cells extended processes into the striatum. In 3 out of the 12 animals, the labeled SVZa cells were distributed along the dorsal and lateral aspects of the striatal boundary. In the remaining five animals, labeled SVZa cells appeared in both locations: within the striatum as well as along the striatal boundary. The dispersion of the transplanted cells within the striatum and the presence of the transplanted SVZa cells all along the striatal boundary, a region corresponding to the lateral cortical stream of migration of the developing forebrain, demonstrates that the isochronically transplanted SVZa cells retained their capacity to migrate.

Neuronal Progenitor Cells of the Neonatal Subventricular Zone Differentiate and Disperse following Transplantation into the Adult Rat Striatum

We have investigated the suitability of a recently identified and characterized population of neuronal progenitor cells for their potential use in the replacement of degenerating or damaged neurons in the mammalian brain. The unique population of neuronal progenitor cells is situated in a well-delineated region of the anterior part of the neonatal subventricular zone (referred to as SVZa). This region can be separated from the remaining proliferative, gliogenic, subventricular zone encircling the lateral ventricles of the forebrain. Because the neurons arising from the highly enriched neurogenic progenitor cell population of the SVZa ordinarily migrate considerable distances and ultimately express the neurotransmitters GABA and dopamine, we have examined whether they could serve as an alternative source of tissue for neural transplantation. SVZa cells from postnatal day 0-2 rats, prelabeled by intraperitoneal injections of the cell proliferation marker BrdU, were implanted into the striatum of adult rats approximately 1 mo after unilateral denervation by 6-OHDA. To examine the spatio-temporal distribution and phenotype of the transplanted SVZa cells, the experimental recipients were perfused at short (less than 1 wk), intermediate (2-3 wk) and long (5 mo) postimplantation times. The host brains were sectioned and stained with an antibody to BrdU and one of several cell-type specific markers to determine the phenotypic characteristics of the transplanted SVZa cells. To identify neurons we used the neuron-specific antibody TuJ1, or antimembrane-associated protein 2 (MAP-2), and anti-GFAP was used to identify astrocytic glia. At all studied intervals the majority of the surviving SVZa cells exhibited a neuronal phenotype. Moreover, morphologically they could be distinguished from the cells of the host striatum because they resembled the intrinsic granule cells of the olfactory bulb, their usual fate. At longer times, a greater number of the transplanted SVZa cells had migrated from their site of implantation, often towards an outlying blood vessel, and the density of cells within the core of the transplant was reduced. Furthermore, there were rarely signs of transplant rejection or a glial scar surrounding the transplant. In the core of the transplant there were low numbers of GFAP-positive cells, indicating that the transplanted SVZa cells, predominantly TuJ1-positive/MAP2-positive, express a neuronal phenotype. Collectively, the propensity of the SVZa cells to express a neuronal phenotype and to survive and integrate in the striatal environment suggest that they may be useful in the reconstruction of the brain following CNS injury or disease.

Immunological Responses to Injury and Grafting in the Central Nervous System of Nonhuman Primates

Allogeneic transplantation for the therapy of human Parkinson's disease is being considered as a viable approach at several clinical centers worldwide. As an attempt to understand the basic biology of central nervous system (CNS) transplantation, our laboratory has developed an experimental nonhuman primate model for human Parkinson's disease and carried out preliminary studies directed at evaluating the potential pathology at the graft site. In addition, studies have been conducted to examine whether such transplantation procedures lead to specific and/or nonspecific immunologic sensitization of the host or results in generalized immunosuppression. Groups of rhesus macaques (Macaca mulatta) were either controls operated (n = 6), autografted with adrenal medullary and peripheral nerve tissue (n = 3), or allografted with fetal mesencephalic tissue (n = 6). Immunohistological studies demonstrated the presence of mononuclear cell infiltrates as early as 1 wk and up to 1 yr postoperatively, although the frequency of the infiltrating cells declined with time. The infiltrates consisted of variable numbers of cells which express CD2+, CD3+, CD4+, CD8+, CD19+, CD22+, CD25+, and CD68+. There appeared to be no difference in the frequency, kinetics, or phenotype of the infiltrating cells in operative controls compared with recipients of auto- or allografts. Tissue sections obtained postoperatively showed low levels of major histocompatibility complex (MHC) Class I antigens and no detectable level of MHC-Class II antigens in neural tissue. A small aliquot of tissue from the operative site was placed in vitro with media containing interleukin-2 (IL-2), which led to the exudation and growth of mononuclear cells that were predominantly CD4+ cells. Phenotypic studies of peripheral blood mononuclear cells (PBMC) from operative controls, auto- and allograft recipient monkeys performed at varying time periods postoperatively failed to show differences in the frequencies of subsets of T-cells, B-cells, NK-cells, or monocytes. Studies on aliquots of the same PBMC failed to show major functional differences in NK-cells, LAK cells, or response to polyclonal mitogens. Finally, recipients of allogeneic mesencephalic grafts failed to show evidence of donor-specific humoral or cellular sensitization. These data indicate that transplantation of autograft adrenal or allograft fetal mesencephalic tissues in the CNS of nonhuman primate did not induce detectable donor-specific sensitization nor nonspecific immunosuppression.

Microsurgical revascularization of the ophthalmic artery

We have developed and performed a microsurgical arterial anastomosis to revascularize the ophthalmic artery in patients with ischemic visual loss, resulting in improvement in visual function. A detailed description of the surgical procedure is discussed as well as the indications for surgery in these cases. An ischemic etiology of visual impairment was predicted by binocular fundus reflectometry, a noninvasive technique to indicate ocular perfusion abnormalities. Encouraging early results suggest that such a revascularization procedure may provide a therapeutic option for a particular group of patients with progressive ischemic visual loss.

Basic fibroblastic growth factor as a potential meningeal angiogenic factor

Vascular supply plays a significant role in the management of skull base tumors. The diagnosis is aided by contrast-enhanced imaging and angiographic techniques, and embolization procedures are used to devascularize certain lesions. The degree of surgical technical difficulty is strongly influenced by the degree of tumor vascularity. Although the importance of this blood supply is clearly understood, the mechanism involved in developing a system of tumor-perfusing vessels is yet to be defined. The development of a vascular network, or angiogenesis, is an important event in allowing tumor proliferation to progress beyond small clusters of cells. Basic fibroblastic growth factor (bFGF) is an especially attractive candidate as an angiogenic growth factor because of its ability to stimulate processes that are characteristic of angiogenesis in vitro. Tumors that involve the meninges may have the ability to liberate normally stored bFGF, which may, in turn, induce new vessel formation for continued tumor proliferation. An immunohistochemical analysis of rodent and bovine meninges to study this phenomenon is described. The dura, arachnoid, and their associated vessels are shown clearly to contain this growth factor. Ultimately, an adjuvant therapy based on the inhibition of angiogenesis may provide a reasonable alternative to aggressive surgical approaches in skull base tumors that are incompletely resectable.

Ventral intermediate thalamic stimulation in complex tremor syndromes

BACKGROUND/AIMS

We report on deep brain stimulation (DBS) in the ventral intermediate part of the thalamus in 4 patients with complex tremor syndromes, 2 classified as Holmes tremor (HT) and 2 as thalamic tremor (TT).

RESULTS

Three out of 4 patients showed intraoperative improvement and underwent DBS implantation. One patient with TT without intraoperative improvement was not provided with an implant. A sustained beneficial effect was present after a follow-up ranging from 20 months to 7 years, although there was partial persistence of the intentional tremor and of proximal myoclonic-dystonic movements. The mean global clinical impression score was 2. In 1 HT patient the benefit persisted after battery failure.

CONCLUSION

The study confirms that ventral intermediate thalamic DBS can provide long-term efficacy for HT and TT. While the patients experienced considerable and lasting functional improvement, the effect was incomplete and not all elements of their complex movement disorders were equally suppressed.

Axosomatic synapses on granule cells are preserved in human non-infiltrating tumour or lesion-related and mesial temporal sclerotic epilepsy, but markedly reduced in tumour-infiltrated dentate gyrus with or without epilepsy

Granule cells of the human hippocampal dentate gyrus were examined. In controls, granule cells displayed somatic spines and cell nuclei with small infoldings. In addition, the cytoplasm of human granule cells always displayed lipofuscin. Subsurface cisterns of endoplasmic reticulum were frequently observed in the human granule cells. Two types of axosomatic synapses were found; most frequently symmetric and less frequently asymmetric. Many of the axosomatic synapses were isolated by glial processes in tumour or lesion-related epileptic patients, but the ultrastructural characteristics of granule cells were not different from those of the control patients. Large bundles of reactive astroglial fibres appeared regularly in all layers of the dentate gyrus. In tumour infiltrated hippocampi, glial processes dominated the neuropil and the number of perisomatic synapses was markedly reduced. Reduction in the number of perisomatic synapses did not correlate with severity and duration of seizures but did correlate with the malignancy of the tumour. It is suggested that reduction of perisomatic inhibition may not be a characteristic of granule cells in the epileptic human dentate gyrus.

Remission of intractable partial epilepsy following implantation of intracranial electrodes

Six patients with medically intractable partial epilepsy (IPE) underwent seizure localization with intracranial EEG using intracerebral or subdural electrodes. No surgical resection was performed, but all had seizure remission ranging from 11 months to 15 years. Invasive monitoring may rarely produce remission of IPE, possibly through interruption of seizure propagation pathways.

Stereotactic radiosurgery of malignant and benign intracranial lesions utilizing a patient rotator

This study examines the characteristics of the patient groups, treatment parameters, and results of therapy for 126 intracranial lesions treated with stereotactic radiosurgery utilizing a "patient rotator" and a linear accelerator. A retrospective review was conducted and data on 122 patients (21 patients with arteriovenous malformations-AVMs, 40 patients with 41 metastatic tumors, 24 patients with malignant gliomas and 37 patients with other benign lesions) were analyzed. Clinical and radiographic response was obtained from chart review and/or telephone follow-up. The average follow-up was 12.1, 13.0, 5.7, and 23.1 months in patients with AVMs, malignant gliomas, metastases, and other lesions, respectively. Median survival times (MST) of the metastatic and glioma group were 9 and 38 months, respectively. Complete or partial radiographic response at follow-up was seen in 62.5% of AVM patients, 33.3% of patients with metastases, 11.8% of patients with malignant gliomas, and 19.3% of patients with other lesions. (1) Local control of brain metastases and benign intracranial lesions can be obtained with single dose stereotactic radiosurgery. (2) The MST and local control rate for metastatic disease obtained are comparable with those in the literature. (3) The patient rotator method for stereotactic radiosurgery is an effective tool for treating selected intracranial lesions.

Repetitive transcranial magnetic stimulation does not replicate the Wada test

The authors compared inferior frontal speech arrest from repetitive transcranial magnetic stimulation (rTMS) with bilateral Wada tests in 17 epilepsy surgery candidates. Although rTMS lateralization correlated with the Wada test in most subjects, rTMS also favored the right hemisphere at a rate significantly greater than the Wada test. Postoperative language deficits were more consistent with Wada results. Available methods for inducing speech arrest with rTMS do not replicate the results of Wada tests.

Electrophysiological localization of the substantia nigra in the parkinsonian nonhuman primate

During ablative surgery and implantation of deep-brain stimulators for the treatment of movement disorders, electrophysiological techniques are often used for localization of subcortical targets. New restorative therapies for Parkinson disease, aimed at delivering drugs or cells to the substantia nigra (SN), are becoming available. Therefore, precise surgical approaches to the dopaminergic cell-containing region of the SN are required to avoid damage to nearby structures such as the corticospinal tract and subthalamic nucleus. In a study conducted in nonhuman primates, the authors evaluated the utility and accuracy of electrophysiological techniques in localizing the SN. Three adult rhesus monkeys were used as hosts for intranigral cell transplants. The monkeys were rendered hemiparkinsonian by intracarotid injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. With the aid of stereotactic guidance, chronic recording chambers were placed on the skull of each monkey and directed at the SN. In each monkey, 20 to 40 trajectories were explored with a microelectrode. Spontaneous and movement-related single-unit activities were recorded in the SN, pars reticulata, subthalamic nucleus, globus pallidus, striatum, thalamus, and red nucleus. Motor and ocular responses to microstimulation in the subthalamic area were noted. Using the electrophysiological and stereotactic information that was obtained, three-dimensional maps of the nigral complex were constructed to infer the location of the SN pars compacta. The maps were subsequently used to guide intranigral placement of fetal dopaminergic cells. Accurate delivery was verified by histological analysis. Based on the characteristic electrophysiological properties of the SN and surrounding structures in the parkinsonian state, microelectrode recording techniques may be used to ensure accurate placement of cell transplantation in the intranigral region.

Behavioral evaluation of hemiparkinsonian MPTP monkeys following dopamine pharmacological manipulation and adrenal co-graft transplantation

Bradykinesia and rigidity are the symptoms that most directly correlate with loss of striatal dopamine in Parkinson's disease. In the hemiparkinsonian (HP) monkey, this is represented by paucity of movement as measured by coli puterized movement analysis, diminished manual dexterity on clinical examination, and diminished performance on operant behavioral tasks. The present study used an MPTP-induced HP model in rhesus monkeys to evaluate the effectiveness of adrenal medullary and peripheral nerve co-grafts in diminishing parkinsonian symptoms. Unoperated controls (N = 4), surgical controls with caudate lesioning (N = 4), and caudate co-grafted (N = 4) HP monkeys demonstrated diminished movement in the home cage following MPTP. This behavior persisted in unoperated controls, but improved in both surgical control and co-grafted monkeys. Functional hand dexterity evaluations demonstrated similar impairment in all three groups but only surgical controls and co-grafted monkeys demonstrated improvement. In general, rotational behavior in response to apomorphine was consistent with recovery of function in surgical controls and co grafted monkeys, but marked between-subject variability precluded group statistical analyses. None of the monkeys could perform the operant task using the affected limb following MPTP. However, the performance of two co-grafted animals demonstrated partial recovery. L-dopa improved operant performance, demonstrating a dopaminergic component to the task. The results demonstrate recovery of behavioral function after surgical treatment, with adrenal co-grafted monkeys showing the greatest degree of improvement.

Direct control of a computer from the human central nervous system

We describe an invasive alternative to externally applied brain-computer interface (BCI) devices. This system requires implantation of a special electrode into the outer layers of the human neocortex. The recorded signals are transmitted to a nearby receiver and processed to drive a cursor on a computer monitor in front of the patient. Our present patient has learned to control the cursor for the production of synthetic speech and typing.

A high-resolution fast spin-echo inversion-recovery sequence for preoperative localization of the internal globus pallidus

A fast spin-echo inversion-recovery (FSE-IR) sequence is described for its utility regarding surgical planning for patients with Parkinson's disease (PD) who are undergoing microelectrode-guided internal globus pallidus (GPi) ablation. Images from thirty-seven adult patients with PD were reviewed and visualization of the GPi, globus pallidus externa (GPe), and the intervening lamina was noted. High-resolution images were acquired from all patients despite the external hardware and the patients' movement disorder. In all cases, the conventional surgical trajectory, determined indirectly by a fixed measurement from the anteroposterior commissure line, was modified by the ability to visualize the GPi and optic tract directly. This sequence facilitated accurate stereotactic targeting.

Treatment of advanced Parkinson's disease by unilateral posterior GPi pallidotomy: 4-year results of a pilot study

To assess the long-term outcome following unilateral pallidotomy for advanced Parkinson's disease, we performed nonblinded Core Assessment Program for Intracerebral Transplantations protocol assessments in 10 of the original 15 patients in our pilot study for 4 years following surgery. Although Unified Parkinson's Disease Rating Scale motor examination scores returned to baseline levels at 3 and 4 years, most patients continued to show sustained improvements in contralateral tremor, akinesia, and drug-induced dyskinesias. Contralateral tremor was absent at 4 years in all seven patients with preoperative tremor. Contralateral "off" arm movement times (averaged for three tasks) decreased by 37% at 1 year and by 30% at 4 years. Contralateral dyskinesia scores improved by 82% at 1 year and by 64% at 4 years. In contrast, after reaching speeds equal to the contralateral side at 1 year, ipsilateral "off" movement times increased by 13% over baseline levels at 4 years. Although most gait and postural stability measures showed modest initial improvement followed by a return to baseline values, "on" stand-walk-sit task performance declined significantly at 4 years. Despite the restriction of our surgeries to one side and the expected natural progression of Parkinson's disease, the results of patient self-assessments suggest that 4 years after unilateral pallidotomy, most patients continue to experience a quality of life above preoperative levels.

Neuronal activity in the basal ganglia in patients with generalized dystonia and hemiballismus

Microelectrode recording was performed in the basal ganglia of 3 patients with generalized dystonia and 1 patient with hemiballismus secondary to a brainstem hemorrhage. Neuronal activity was recorded from the internal and external segments of the globus pallidus and assessed for mean discharge rate and pattern of spontaneous activity. The responses of neurons in the internal segment of the globus pallidus to passive and active movements were also evaluated. Mean discharge rates of neurons in both segments of the pallidum in patients with dystonia and the patient with hemiballismus were considerably lower than those reported for patients with idiopathic Parkinson's disease. In addition, the pattern of spontaneous neuronal activity was highly irregular, occurring in intermittent grouped discharges separated by periods of pauses. Although receptive fields in the dystonia patients were widened and less specific than those reported in normal monkeys, neuronal responses to movement were uncommon in the hemiballismus patient. Before surgery, patients with dystonia experienced abnormal posturing and involuntary movements. Coactivation of agonist-antagonist muscle groups was observed both at rest and during the performance of simple movements. After pallidotomy there was a significant reduction in the involuntary movement associated with these disorders and a more normal pattern of electromyographic activity during rest and movement. Given the improvement in dystonic and hemiballistic movements in these patients after ablation of the sensorimotor portion of the internal segment of the globus pallidus, we suggest that pallidotomy can be an effective treatment for patients with dystonia and also for patients with medically intractable hemiballismus. Based on the finding of decreased neuronal discharge rates in pallidal neurons, we propose that physiologically dystonia most closely resembles a hyperkinetic movement disorder. A model for dystonia is proposed that incorporates the observed changes in the rate and pattern of neuronal activity in the pallidum with data from neuroimaging with positron emission tomography and 2-deoxyglucose studies.

Acute blood flow changes and efficacy of vagus nerve stimulation in partial epilepsy

OBJECTIVE

To determine possible sites of therapeutic action of vagus nerve stimulation (VNS), by correlating acute VNS-induced regional cerebral blood flow (rCBF) alterations and chronic therapeutic responses.

BACKGROUND

We previously found that VNS acutely induces rCBF alterations at sites that receive vagal afferents and higher-order projections, including dorsal medulla, somatosensory cortex (contralateral to stimulation), thalamus and cerebellum bilaterally, and several limbic structures (including hippocampus and amygdala bilaterally).

METHODS

VNS-induced rCBF changes were measured by subtracting resting rCBF from rCBF during VNS, using [O-15]water and PET, immediately before ongoing VNS began, in 11 partial epilepsy patients. T-statistical mapping established relative rCBF increases and decreases for each patient. Percent changes in frequency of complex partial seizures (with or without secondary generalization) during three months of VNS compared with pre-VNS baseline, and T-thresholded rCBF changes (for each of the 25 regions of previously observed significant CBF change), were rank ordered across patients. Spearman rank correlation coefficients assessed associations of seizure-frequency change and t-thresholded rCBF change.

RESULTS

Seizure-frequency changes ranged from 71% decrease to 12% increase during VNS. Only the right and left thalami showed significant associations of rCBF change with seizure-frequency change. Increased right and left thalamic CBF correlated with decreased seizures (p < 0.001).

CONCLUSIONS

Increased thalamic synaptic activities probably mediate some antiseizure effects of VNS. Future studies should examine neurotransmitter-receptor alterations in reticular and specific thalamic nuclei during VNS.

Posterior ventral pallidotomy: techniques and theoretical considerations

1. Microeletrode mapping of the pallidum and adjacent structures allows for precise target identification and localization of critical structures, i.e., optic tract, internal capsule, and external pallidum, which must be spared from lesioning. 2. Microelectrode mapping has provided physiologic-anatomic correlation of determining the optimal target location as related to clinical outcome and has helped to refine the role of stimulation as a tool for target localization. 3. The improved accuracy of this technique should result in more accurate lesion placement which should improve long-term outcome and decrease morbidity.

Magnetic resonance imaging-based stereotactic localization of the globus pallidus and subthalamic nucleus

OBJECTIVE

To optimize the accuracy of initial stereotactic targeting for movement disorders surgery, we performed stereotactic localization of the internal segment of the globus pallidus (GPi) and subthalamic nucleus (STN) using magnetic resonance imaging protocols in which the borders of these nuclei were directly visualized.

METHODS

Fifty-one consecutive cases using the pallidal target and six using the subthalamic target were studied. Localization of these nuclei was performed using the Leksell stereotactic head frame and inversion recovery sequences (GPi) or T2-weighted spin echo sequences (STN). Targeting accuracy and individual variation in the spatial coordinates of these structures were independently measured by identification of nuclear boundaries during multiple microelectrode penetrations.

RESULTS

The lateral and vertical coordinates of an atlas-defined point in the GPi, with respect to the line between the anterior and posterior commissures, was highly variable. Initial targeting the GPi based on direct visualization of the target boundaries (external medullary lamina and optic tract) resulted in greater precision than would be expected using fixed anterior and posterior commissure-based coordinates. Initial targeting the STN using magnetic resonance imaging was sufficiently precise to place the initial microelectrode penetration within STN in all six cases.

CONCLUSION

Magnetic resonance imaging-based initial stereotactic targeting of the GPi, based on direct visualization of the target boundaries, is useful to improve target accuracy over that of purely indirect anterior and posterior commissure-based targeting methods. Initial targeting of the STN was reliably accomplished by direct visualization. However, there remains sufficient variability that the final target location in both GPi and STN required electrophysiological mapping in all cases.

Intranigral transplantation of fetal substantia nigra allograft in the hemiparkinsonian rhesus monkey

Current clinical protocols for fetal cell transplantation for Parkinson's disease (PD) have focused on restoring dopamine in the striatum. However, there are now a number of human transplant recipients who have had robust innervation of the striatum by dopaminergic grafts (documented by positron emission tomography or by autopsy), but only a partial improvement in parkinsonian motor signs. Thus, there is a need for improved transplant strategies. In animal models of PD, there is recent evidence that restoring dopamine in the substantia nigra, instead of or in addition to the striatum, may be important to correct abnormal motor behavior. This pilot study examined the morphological features and behavioral effects of fetal dopaminergic neuronal allografts placed into the substantia nigra of three 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated hemiparkinsonian rhesus monkeys. We show that grafts can survive in host substantia nigra. Characteristics of the graft-host interface were variable. In one animal, reinnervation of host substantia nigra was observed, and this animal showed behavioral improvement in a reach-and-retrieval task.

Alumina gel injections into the temporal lobe of rhesus monkeys cause complex partial seizures and morphological changes found in human temporal lobe epilepsy

The goal of the present study was to determine whether alumina gel injections into temporal lobe structures cause complex partial seizures (CPS) and pathological changes observed in human temporal lobe epilepsy. Rhesus monkeys with alumina gel injections in the amygdala, perirhinal and entorhinal cortices, or Ammon's horn and dentate gyrus all initially displayed focal pathological electroencephalographic (EEG) slowing limited to the site of injection. After clinical seizures developed, they also displayed widespread pathological EEG slowing over both hemispheres, interictal and ictal epileptiform EEG abnormalities limited to the mesial-inferior temporal lobe on the side of injection, and different degrees of spread to other ipsilateral and contralateral structures. Noninjected control and nonepileptic monkeys with injections into the middle and inferior temporal gyri displayed no hippocampal neuronal loss or mossy fiber sprouting. When alumina gel was injected into the amygdala, CPS began within 3-6 weeks and degeneration of neurons and gliosis occurred in the perirhinal cortex or the hippocampus, with consequent sprouting of mossy fibers in the dentate gyrus. Dispersion of the granule cell layer was also observed. Other monkeys with alumina gel in the perirhinal and entorhinal cortices developed CPS within 2-3 weeks after the injections and displayed mossy fiber sprouting only after 4 weeks after the injections. Alumina gel in Ammon's horn and the dentate gyrus also induced CPS, but mossy fiber sprouting was limited to sites immediately adjacent to the injection, probably because none survived more than 4 weeks after the injections. This nonhuman primate model of CPS displayed similar anatomical, behavioral, and EEG features as observed in human temporal lobe epilepsy and provides opportunities to analyze the chronological sequence of epileptogenesis and to test potential therapies.

Ablative surgery and deep brain stimulation for Parkinson's disease

Surgical options for Parkinson's disease (PD) are rapidly expanding and include ablative procedures, deep brain stimulation, and cell transplantation. The target nuclei for ablative surgery and deep brain stimulation are the motor thalamus, the globus pallidus, and the subthalamic nucleus. Multiple factors have led to the resurgence of interest in the surgical treatment of PD: 1) recognition that long-term medical therapy for PD is often unsatisfactory, with patients eventually suffering from drug-induced dyskinesias, motor fluctuations, and variable responses to medication; 2) greater understanding of the pathophysiology of PD, providing a better scientific rationale for some previously developed procedures and suggesting new targets; and 3) use of improved techniques, such as computed tomography- and magnetic resonance imaging-guided stereotaxy and single-unit microelectrode recording, making surgical intervention in the basal ganglia more precise. We review the present status of ablative surgery and deep brain stimulation for PD, including theoretical aspects, surgical techniques, and clinical results.

Brain blood flow alterations induced by therapeutic vagus nerve stimulation in partial epilepsy: I. Acute effects at high and low levels of stimulation

PURPOSE

Left cervical vagus nerve stimulation (VNS) decreases complex partial seizures (CPS) by unknown mechanisms of action. We hypothesized that therapeutic VNS alters synaptic activities at vagal afferent terminations and in sites that receive polysynaptic projections from these medullary nuclei.

METHODS

Ten patients with partial epilepsy underwent positron emission tomographic (PET) measurements of cerebral blood flow (BF) three times before and three times during VNS. Parameters for VNS were at high levels for 5 patients and at low levels for 5. Resting BF measurements were subtracted from measurements during VNS in each subject. Subtraction data were averaged in each of 2 groups of 5 patients. t Tests were applied to BF changes in brain regions that receive vagal afferents and projections (significant at p < 0.05, corrected for repeated measures).

RESULTS

In both the low- and high-stimulation groups during VNS, brain BF was (a) increased in the rostral, dorsal-central medulla; (b) increased in the right postcentral gyrus, (c) increased bilaterally in the hypothalami, thalami, and insular cortices, and in cerebellar hemispheres inferiorly; and (d) decreased bilaterally in hippocampus, amygdala, and posterior cingulate gyri. The high-stimulation group had greater volumes of activation and deactivation sites.

CONCLUSIONS

Our findings suggest that left cervical VNS acutely increases synaptic activity in structures directly innervated by central vagal structures and areas that process left-sided somatosensory information, but VNS also acutely alters synaptic activity in multiple limbic system structures bilaterally. These findings may reflect sites of therapeutic actions of VNS.

Microelectrode-guided pallidotomy: technical approach and its application in medically intractable Parkinson's disease

OBJECT

The authors describe the microelectrode recording and stimulation techniques used for localizing the caudal sensorimotor portion of the globus pallidus internus (GPi) and nearby structures (internal capsule and optic tract) in patients undergoing GPi pallidotomy.

METHODS

Localization is achieved by developing a topographic map of the abovementioned structures based on the physiological characteristics of neurons in the basal ganglia and the microexcitable properties of the internal capsule and optic tract. The location of the caudal GPi can be determined by "form fitting" the physiological map on relevant planes of a stereotactic atlas. A sensorimotor map can be developed by assessing neuronal responses to passive manipulation or active movement of the limbs and orofacial structures. The internal capsule and optic tract, respectively, can be identified by the presence of stimulation-evoked movement or the patient's report of flashes or speckles of light that occur coincident with stimulation. The optic tract may also be located by identifying the neural response to flashes of light. The anatomical/physiological map is used to guide lesion placement within the sensorimotor portion of the pallidum while sparing nearby structures, for example, the external globus pallidus, nucleus basalis, optic tract, and internal capsule. The lesion location and size predicted by using physiological recording together with thin-slice high-resolution magnetic resonance imaging reconstructions of the lesion were confirmed in one patient on histological studies.

CONCLUSIONS

These data provide important information concerning target identification for ablative or deep brain stimulation procedures in idiopathic Parkinson's disease and other movement disorders.

Restoration of neural output from a paralyzed patient by a direct brain connection

Patients with severe paralysis of limbs, face and vocal apparatus may be intelligent and aware and yet, tragically, unable to communicate. We describe a communication link for such a 'locked-in' patient with amyotrophic lateral sclerosis. We recorded action potentials in her brain over several months by means of an electrode that induces growth of myelinated fibers into its recording tip. She was able to control the neural signals in an on/off fashion. This result is an important step towards providing such patients with direct control of their environment by interfacing with a computer. Additionally, it indicates that restoration of paralyzed muscles may be possible by using the signals to control muscle stimulators.

Deep brain stimulation for movement disorders

Chronic deep brain stimulation (DBS) is a promising technique for the treatment of movement disorders. Thalamic stimulation is now an established surgical procedure for parkinsonian and essential tremor. Pallidal and subthalamic stimulation are under active investigation as treatments for Parkinson's disease. Although high-frequency DBS at these sites has similar behavioral effects as lesioning, the physiologic mechanisms underlying the beneficial effect of DBS is not well understood and may be extremely complex. DBS offers a potential advantage over ablative therapy because stimulation-induced complications are reversible, and the stimulation parameters are adjustable to minimize complications and maximize therapeutic effects. With this added safety, bilateral stimulation or use of a stimulator following a prior procedure may be preferable to bilateral ablative procedures.

Neuronal progenitor cells of the neonatal subventricular zone differentiate and disperse following transplantation into the adult rat striatum

We have investigated the suitability of a recently identified and characterized population of neuronal progenitor cells for their potential use in the replacement of degenerating or damaged neurons in the mammalian brain. The unique population of neuronal progenitor cells is situated in a well-delineated region of the anterior part of the neonatal subventricular zone (referred to as SVZa). This region can be separated from the remaining proliferative, gliogenic, subventricular zone encircling the lateral ventricles of the forebrain. Because the neurons arising from the highly enriched neurogenic progenitor cell population of the SVZa ordinarily migrate considerable distances and ultimately express the neurotransmitters GABA and dopamine, we have examined whether they could serve as an alternative source of tissue for neural transplantation. SVZa cells from postnatal day 0-2 rats, prelabeled by intraperitoneal injections of the cell proliferation marker BrdU, were implanted into the striatum of adult rats approximately 1 mo after unilateral denervation by 6-OHDA. To examine the spatio-temporal distribution and phenotype of the transplanted SVZa cells, the experimental recipients were perfused at short (less than 1 wk), intermediate (2-3 wk) and long (5 mo) postimplantation times. The host brains were sectioned and stained with an antibody to BrdU and one of several cell-type specific markers to determine the phenotypic characteristics of the transplanted SVZa cells. To identify neurons we used the neuron-specific antibody TuJ1, or antimembrane-associated protein 2 (MAP-2), and anti-GFAP was used to identify astrocytic glia. At all studied intervals the majority of the surviving SVZa cells exhibited a neuronal phenotype. Moreover, morphologically they could be distinguished from the cells of the host striatum because they resembled the intrinsic granule cells of the olfactory bulb, their usual fate. At longer times, a greater number of the transplanted SVZa cells had migrated from their site of implantation, often towards an outlying blood vessel, and the density of cells within the core of the transplant was reduced. Furthermore, there were rarely signs of transplant rejection or a glial scar surrounding the transplant. In the core of the transplant there were low numbers of GFAP-positive cells, indicating that the transplanted SVZa cells, predominantly TuJ1-positive/MAP2-positive, express a neuronal phenotype. Collectively, the propensity of the SVZa cells to express a neuronal phenotype and to survive and integrate in the striatal environment suggest that they may be useful in the reconstruction of the brain following CNS injury or disease.

Immunological responses to injury and grafting in the central nervous system of nonhuman primates

Allogeneic transplantation for the therapy of human Parkinson's disease is being considered as a viable approach at several clinical centers worldwide. As an attempt to understand the basic biology of central nervous system (CNS) transplantation, our laboratory has developed an experimental nonhuman primate model for human Parkinson's disease and carried out preliminary studies directed at evaluating the potential pathology at the graft site. In addition, studies have been conducted to examine whether such transplantation procedures lead to specific and/or nonspecific immunologic sensitization of the host or results in generalized immunosuppression. Groups of rhesus macaques (Macaca mulatta) were either controls operated (n = 6), autografted with adrenal medullary and peripheral nerve tissue (n = 3), or allografted with fetal mesencephalic tissue (n = 6). Immunohistological studies demonstrated the presence of mononuclear cell infiltrates as early as 1 wk and up to 1 yr postoperatively, although the frequency of the infiltrating cells declined with time. The infiltrates consisted of variable numbers of cells which express CD2+, CD3+, CD4+, CD8+, CD19+, CD22+, CD25+, and CD68+. There appeared to be no difference in the frequency, kinetics, or phenotype of the infiltrating cells in operative controls compared with recipients of auto- or allografts. Tissue sections obtained postoperatively showed low levels of major histocompatibility complex (MHC) Class I antigens and no detectable level of MHC-Class II antigens in neural tissue. A small aliquot of tissue from the operative site was placed in vitro with media containing interleukin-2 (IL-2), which led to the exudation and growth of mononuclear cells that were predominantly CD4+ cells. Phenotypic studies of peripheral blood mononuclear cells (PBMC) from operative controls, auto- and allograft recipient monkeys performed at varying time periods postoperatively failed to show differences in the frequencies of subsets of T-cells, B-cells, NK-cells, or monocytes. Studies on aliquots of the same PBMC failed to show major functional differences in NK-cells, LAK cells, or response to polyclonal mitogens. Finally, recipients of allogeneic mesencephalic grafts failed to show evidence of donor-specific humoral or cellular sensitization. These data indicate that transplantation of autograft adrenal or allograft fetal mesencephalic tissues in the CNS of nonhuman primate did not induce detectable donor-specific sensitization nor nonspecific immunosuppression.

Visual fields in patients with posterior GPi pallidotomy

The objective of this study was to describe the incidence and types of visual field defects after posterior globus pallidus internus (GPi) pallidotomy for Parkinson's disease. The creation of the pallidotomy lesion carries a risk of damaging neighboring structures such as the optic tract. The reported frequency of visual field defects in patients after pallidotomy varies from 0 to 40%. Goldmann visual field testing was performed on 40 patients who underwent microelectrode-guided posterior GPi pallidotomy. The optic tract was identified during the procedure by listening during microelectrode recording for the evoked responses to light flashes and by assessing stimulation-induced subjective responses. After the first 18 patients, lesioning thresholds were increased from 0.5 to > or =1.0 mA so that the lesion was placed more distant from the optic tract. The location of individual lesions was determined on postsurgical MRI. Three patients (7.5%) had visual field defects likely related to the pallidotomy. These were contralateral homonymous superior quadrantanopias, associated in two patients with small paracentral scotomas. The incidence of visual field defects with the early technique was 11% (2/18) and decreased to 4.5% (1/22) after thresholds for lesioning were increased. Except for the location of the lesion relative to the optic tract (more ventral, adjacent to or extending into the optic tract), no other variable correlated with a post-pallidotomy visual field defect. Microelectrode-guided GPi pallidotomy is a relatively safe procedure as regards visual function even when the optic tract is used as a guide for lesion placement.

Pre- and postoperative MR evaluation of stereotactic pallidotomy

PURPOSE

Stereotactic pallidotomy, which has evolved as a result of technological advances in high-resolution MR imaging and microelectrode electrophysiological recording, is becoming a major form of treatment for patients with Parkinson disease in whom medical therapy has failed. We describe the location and appearance of the pallidotomy lesion on high-resolution MR images.

METHODS

MR images in 83 patients (60 men and 23 women) who underwent stereotactic pallidotomy were reviewed retrospectively. The prepallidotomy screening study included standard spin-echo and gradient-echo sequences. After placement of a stereotactic headframe, volume-acquisition T1-weighted spoiled gradient-echo images were acquired for target localization in the posteroventral internal globus pallidus. One to three days after the pallidotomy, volume-acquisition T1-weighted and standard spin-echo sequences were obtained. In 16 patients, turbo spin-echo inversion recovery images also were obtained before and after surgery. The diameter, signal intensity, and location of the lesions relative to the midcommissural point and the intercommissural line were noted.

RESULTS

The average lesion volume was 118 mm3 while that of the lesion-edema complex was 420 mm3. The midportion of the lesion was located on average 3.5 mm anterior to the midcommissural point, 21 mm lateral to the middle of the third ventricle, and 1.2 mm inferior to the intercommissural line. Signal intensity of the lesions varied, but all had a rim of edema. Forty-two patients had edema extending into the optic tract, four had increased signal in the ipsilateral basal ganglia on T2-weighted images, and seven had hemorrhage involving the ipsilateral caudate, internal capsule, and putamen. All patients experienced some improvement in contralateral bradykinesia, rigidity, and dystonia.

CONCLUSION

The acute pallidotomy lesion is invariably located within the posteroventral internal globus pallidus, is usually hyperintense centrally on T1-weighted and turbo spin-echo inversion recovery MR images, and has a thin rim of edema. Edema extending into the ipsilateral optic tract was a common finding, but this series of patients evinced no visual changes.

Effect of stereotaxic intrastriatal cografts of autologous adrenal medulla and peripheral nerve in Parkinson's disease: two-year follow-up study

Studies in nonhuman primates with experimental parkinsonism have shown that intrastriatal cografts of autologous adrenal medulla and peripheral nerve yield greater behavioral improvement and graft survival than do adrenal medulla grafts alone. To test these observations, five patients with advanced Parkinson's disease were selected to receive unilateral intrastriatal adrenal medulla-intercostal nerve cografts. They were evaluated using the Core Assessment Program for Intracerebral Transplantation (CAPIT) protocol. Three of these patients also underwent quantitative motor testing for the measurement of upper limb bradykinesia (movement time; MT). Following right flank adrenalectomy, cografts consisting of small fragments of adrenal medullary tissue and minced intercostal nerve were stereotaxically implanted into three targets in the right striatum using computerized tomography guidance. Surgery was uneventful and postoperative magnetic resonance imaging revealed accurate placement of the grafts. No morbidity was encountered. Results of 24 months of clinical and quantitative motor assessments postoperatively are reported. Total UPDRS motor scores in the "off" state improved from a mean preoperative score of 39.5 to 32.1 at 3, 29.7 at 6, 27.6 at 9, 28.5 at 12, 31.4 at 18, and 26.5 at 24 months after surgery. Total timed motor test scores during the "off" state improved 17.9% at 6, 23.3% at 9, 18.2% at 12, 38.2% at 18, and 34.9% at 24 months postoperatively compared to baseline. Movement time showed statistically significant improvement (repeated measures ANOVA, P < 0.05) in the left arm (contralateral to surgery) in all three patients tested. These results indicate that stereotaxic intrastriatal implantation of autologous adrenal medulla-peripheral nerve cografts can be performed safely and clinical improvement from this procedure is sustained for a period of 24 months. The clinical improvement was paralleled by improvement in objective, quantitative motor testing.

Polymer-encapsulated PC-12 cells demonstrate high-affinity uptake of dopamine in vitro and 18F-Dopa uptake and metabolism after intracerebral implantation in nonhuman primates

Intracranial implantation of polymer-encapsulated PC-12 cells has been shown to improve motor behavioral performance in animal models of Parkinson's disease. The purpose of this blinded study was to examine whether such improvement is associated with the active uptake and metabolism of dopamine precursors by intracerebrally implanted polymer-encapsulated PC-12 cells. In an in vitro experiment we demonstrate that 3H-dopamine uptake by PC-12 cells was 10(8) fmol/min x 10(6) cells, and that this uptake can be specifically blocked 88% by the addition of 10nM of nomifensine. In the in vivo experiments, polymer-encapsulated PC-12 cells were implanted in four MPTP-treated monkeys into the left deep parietal white matter (R1) or left striatum (R2-4). A fifth MPTP-treated monkey (R5) served as a control and received left striatal implants of empty capsules. 18-F-Dopa Positron Emission Tomography (PET) imaging was performed on each monkey before and after implantation surgery by blinded investigators. PET images obtained 5-13 wk after implantation demonstrated well delineated focal areas of high 18F-dopa uptake in R1, R2, and R4. The focal area of high 18F-dopa uptake in R1 precisely coregistered on a brain magnetic resonance image to the site of implantation. R3 (in whom the polymer-encapsulated PC-12 cells demonstrated poor cell survival upon explantation) and R5 (empty capsules) failed to demonstrate any area of increased 18F-dopa uptake in their PET images. Histological examination of the host brain revealed no sprouting of dopaminergic nerve terminals around the implantation sites of the polymer-encapsulated PC-12 cells. These results indicate that the previously noted behavioral improvement after intrastriatal implantation of polymer encapsulated PC-12 cells is at least in part due to their highly specific uptake and metabolism of dopamine precursors. Furthermore, these data suggest that polymer-encapsulated PC-12 cells can store, reuptake, and functionally replenish dopamine and therefore, may be an effective treatment for Parkinson's disease.

The role of pallidotomy in Parkinson's disease and dystonia

Pallidotomy has been re-explored for the treatment of Parkinson's disease and is now being used for the treatment of medically intractable dystonia. Although initial results are favourable for both disorders, determination of the long term benefits will require well controlled clinical trials.

Activity of single action potentials in monkey motor cortex during long-term task learning

Studies using continuous recording of neural activity during long-term learning are now possible with an implanted neurotrophic electrode. During recording of individual cortical action potentials in monkeys performing a reach and grasp task, we were able to follow the gradual change in firing of several action potentials as the task was learned. Control experiments suggest that the neurons involved in the learning were initially silent.

Dopaminergic and GABAergic interneurons of the olfactory bulb are derived from the neonatal subventricular zone

Earlier studies in our laboratory have demonstrated that a discrete region of the anterior part of the neonatal subventricular zone (SVZa) contains exclusively neuronal progenitor cells. The descendants of the SVZa progenitor cells are destined for the granule cell and glomerular layers of the olfactory bulb, where they differentiate into granule and periglomerular cells, the interneurons of the olfactory bulb, respectively. In the present set of experiments we examined the neurotransmitter phenotype of the SVZa-derived cells. In order to label SVZa-derived cells, the cell proliferation marker bromodeoxyuridine (BrdU) was injected into the SVZa of postnatal day 2 (P2) rats. After 3 weeks, by which time most of the SVZa-derived cells have migrated to their final destination in the bulb, the animals were perfused and their brains processed for immunohistochemistry. To identify the neurotransmitter phenotype of the SVZa-derived cells, sagittal sections of the forebrain, including the olfactory bulb, were double-labeled with an antibody to BrdU in conjunction with an antibody to gamma-amino-butyric acid (GABA) or tyrosine hydroxylase (TH), the rate limiting enzyme in the synthesis of dopamine. Using simultaneous indirect immunofluorescence to detect the presence of single- and double-labeled cells, we found that 59% and 51% of the BrdU-positive cells were immunoreactive for GABA in the granule cell and glomerular layers, respectively. In addition, 10% of the BrdU-positive periglomerular cells were immunoreactive for TH. The presence of double-labeled (BrdU-positive/GABA-positive and BrdU-positive/TH-positive) cells in the olfactory bulb, demonstrates that the SVZa is a source of the GABAergic and dopaminergic interneurons of the olfactory bulb during postnatal development.

Treatment of advanced Parkinson's disease by posterior GPi pallidotomy: 1-year results of a pilot study

The effects of posterior internal pallidal ablation (GPi pallidotomy) on parkinsonian signs and symptoms were studied in 15 patients with medically intractable Parkinson's disease (PD). The sensorimotor territory of the internal portion of the globus pallidus and the adjacent optic tract and internal capsule were identified with microelectrode recording and stimulation. Radiofrequency lesions were then created in the identified sensorimotor territory. Pallidotomy significantly improved all cardinal parkinsonian motor signs (tremor, rigidity, akinesia/bradykinesia, and gait dysfunction) and reduced drug-induced motor fluctuations and dyskinesias. The improvements occurred predominately contralateral to the lesion, but were also present ipsilaterally. Early postoperative (3-month), mean total United Parkinson's Disease Rating Scale scores improved by 30.1% from preoperative values. Mean combined "on/off" Schwab and England Scale scores, a measure of functional independence, increased from 48.8% to 73.0% postoperatively. The mean total United Parkinson's Disease Rating Scale and Schwab and England scores did not show a statistically significant decline over the 1-year postoperative period. Surgery resulted in little morbidity, including a lack of significant deficits on neuropsychological and psychiatric testing. Physical and social functioning and vitality measures on the Medical Outcome Scale also showed significant improvement over the postoperative period. The findings of this pilot study demonstrate that ablation of the sensorimotor portion of the internal pallidum is a highly effective treatment for advanced PD, with benefits sustained at 1 year.

Temporal lobe epilepsy and performance on the Wisconsin Card Sorting Test

The replicability of previous evidence for differential performance between left and right temporal lobe epileptic patients on the Wisconsin Card Sorting Test (WCST) was evaluated in a new sample of candidates for focal resection. Many subjects obtained high scores on indices of perseveration, which are commonly thought to reflect frontal dysfunction, but there were no differences in performance between patients with language-dominant and nondominant temporal foci. The findings confirm existing evidence that performance decrements on the WCST can be associated with epileptic foci and focal lesions in nonfrontal brain lesions.

Intracranial adenoid cystic carcinoma: case report and review of the literature

BACKGROUND

Adenoid cystic carcinoma (cylindroma) is a relatively common head and neck tumor that is slow growing, but locally aggressive and thus prone to recurrence. It is of particular interest to neurosurgeons and neurologists because of its tendency to locally infiltrate neural structures and to spread perineurally. Intracranial involvement has been regarded as rare.

METHODS

A case report of a patient with adenoid cystic carcinoma involving the Gasserian ganglion region is presented. The world literature on intracranial involvement of adenoid cystic carcinoma is reviewed. A discussion of the characteristics of this lesion is provided.

RESULTS

Our literature review revealed 119 previously reported cases of adenoid cystic carcinoma with intracranial involvement. Our case represents only the tenth reported intracranial case with an unknown primary site.

CONCLUSIONS

Although intracranial adenoid cystic carcinoma is regarded as rare, we have accumulated over 100 such reports. A wide variety of primary sites and intracranial sites have been described.

Migration patterns of neonatal subventricular zone progenitor cells transplanted into the neonatal striatum

Our previous studies have shown that the progeny of the neuronal progenitor cells localized in a discrete region of the anterior part of the neonatal subventricular zone, referred to as the SVZa, migrate tangentially along a stereotypical and extended pathway to the olfactory bulb, and then turn radially into one of the overlying cellular layers. In this study we have examined whether the SVZa cells retain their ability to migrate and disperse when heterotopically transplanted into the striatum. SVZa cells from P0-P2 rat pups were microdissected, dissociated, labeled with the lipophilic, fluorescent dye PKH26 or the cell proliferation marker BrdU, and then transplanted into the neonatal (P0-P2) striatum. Examination of the striatum a few days after transplantation revealed aggregates of heavily labeled BrdU-positive, SVZa cells in the striatum, often situated near blood vessels. Two to four weeks after transplantation, however, the labeled SVZa cells had disseminated from their site of implantation and showed three patterns of distribution. In none of the cases was the implantation site detectable in the striatum, signifying that the cells had become incorporated in the host brain. Of the 12 brains analyzed for cell distribution, transplanted SVZa cells were confined to the striatum in 4 cases. The cells were present as individual cells or in small groups of usually two to four cells. When PKH26 was used, we found that many of the transplanted cells extended processes into the striatum. In 3 out of the 12 animals, the labeled SVZa cells were distributed along the dorsal and lateral aspects of the striatal boundary. In the remaining five animals, labeled SVZa cells appeared in both locations: within the striatum as well as along the striatal boundary. The dispersion of the transplanted cells within the striatum and the presence of the transplanted SVZa cells all along the striatal boundary, a region corresponding to the lateral cortical stream of migration of the developing forebrain, demonstrates that the isochronically transplanted SVZa cells retained their capacity to migrate.

A comparison of the patterns of migration and the destinations of homotopically transplanted neonatal subventricular zone cells and heterotopically transplanted telencephalic ventricular zone cells

The cells arising in the anterior part of the subventricular zone (SVZa) migrate along a well-demarcated pathway which lacks radial glial fibers to the olfactory bulb where they differentiate into interneurons of the granule cell layer or glomerular layer (Luskin, 1993, Neuron 11, 173). To analyze the mechanisms underlying this highly directed migration, we have compared the migratory behavior of unmanipulated SVZa-derived cells to that of homotopically transplanted SVZa cells and of heterotopically transplanted telencephalic ventricular zone (VZ) cells that ordinarily migrate in association with radial glial fibers. To identify the phenotype of the SVZa progenitor cells prior to their transplantation, we characterized them in vitro using cell type-specific markers. After 1 day in culture nearly all the SVZa cells were stained with TuJ1, a neuron-specific marker; only an occasional cell exhibited a glial phenotype as judged by the presence of GFAP-immunoreactivity. This indicates that SVZa cells express a neuronal phenotype. To reveal the spatiotemporal distribution of homotopically transplanted neonatal SVZa cells in a host brain, dissociated SVZa cells from Postnatal Day 0 (P0)-P2 animals were labeled with the lipophilic dye PKH26 or the cell proliferation marker BrdU and implanted into the SVZa of host animals of the same age. Within the first week after transplantation there were vast numbers of labeled cells throughout the pathway. Over the next 2 weeks the labeled cells migrated into the overlying cellular layer of the olfactory bulb and began to differentiate, and within 4 weeks the transplanted cells had reached their final positions in the granule cell and glomerular layers of the olfactory bulb in the same proportions as for unmanipulated SVZa-derived cells. While en route to the olfactory bulb the homotopically transplanted cells never strayed from the migratory pathway. In contrast, heterotopically transplanted VZ cells from the embryonic telencephalon did not undergo migration although they did differentiate. These results demonstrate that the homotopically transplanted SVZa-derived cells adopt a mode of migration indistinguishable from that ordinarily utilized by SVZa-derived neurons and that the VZ cells are unable to decipher the same set of guidance cues.

Slowly progressive apraxia in Alzheimer's disease

Slowly progressive apraxia due to Alzheimer's disease was encountered in a 66 year old, right handed man whose initial impairments included coordinated movements of the left hand and some features of the alien hand syndrome. Over four years, the patient developed progressively worsening deficits of memory and language. A biopsy of his right temporal lobe showed numerous plaques and neurofibrillary tangles. Pronounced right parietal lobe hypoperfusion on serial SPECT suggests involvement of this region in contralateral praxis.