Oleg V. Kopyov

Quantitative proton-decoupled 31P MRS and 1H MRS in the evaluation of Huntington's and Parkinson's diseases

Objective: To determine cerebral energy status in patients with Huntingtons disease(HD) and Parkinsons disease (PD). Methods: The study included 15 patients with DNA-proven, symptomatic HD and five patients with medically treated, idiopathic PD, all of whom were candidates for neurotransplant treatment, as well as 20 age-related normal subjects. Quantitative noninvasive, MRI-guided proton MRS was performed of single volumes in putamen of basal ganglia (BG), occipital gray matter, and posterior parietal white matter; in addition, quantitative phosphorus and proton-decoupled phosphorus MRS of superior biparietal white and gray matter was done. Outcome measures were quantitative metabolite ratios and millimolar concentrations of neuronal and glial markers, creatine (Cr) and adenosine triphosphate (ATP), and intracellular pH. Results: In volume-corrected control BG (10.46 ± 0.37 mM), [Cr] was 29%(p < 0.05) higher than in control gray matter (8.10 ± 1.04 mM). In HD and PD, energy metabolism was not abnormal in the four cerebral locations measured by MRS. No increase in cerebral lactate or decrease in phosphocreatine and ATP was detected. Small, systematic abnormalities in N-acetylaspartate (NAA, ddecreased), Cr (decreased), choline-containing compounds (Cho, increased), and myoinositol (mI, increased) were demonstrable in all patients individually and in summed spectra but were insufficient to make diagnosis possible in the individual patient. Conclusion: Previously described failure of global energy metabolism in HD was not confirmed. However, quantitative 1-hydrogen MRS and decoupled 31-phosphorus MRS are sensitive to ±10% alterations in key cerebral metabolites, and may be of value in noninvasive monitoring of appropriate therapies.

Gamma knife thalamotomy for treatment of tremor: long-term results

The purpose of this paper was to note a potential source of error in magnetic resonance (MR) imaging. Magnetic resonance images were acquired for stereotactic planning for GKS of a vestibular schwannoma in a female patient. The images were acquired using three-dimensional sequence, which has been shown to produce minimal distortion effects. The images were transferred to the planning workstation, but the coronal images were rejected. By examination of the raw data and reconstruction of sagittal images through the localizer side plate, it was clearly seen that the image of the square localizer system was grossly distorted. The patient was returned to the MR imager for further studies and a metal clasp on her brassiere was identified as the cause of the distortion.A-60-year-old man with medically intractable left-sided maxillary division trigeminal neuralgia had severe cardiac disease, was dependent on an internal defibrillator and could not undergo magnetic resonance imaging. The patient was successfully treated using computerized tomography (CT) cisternography and gamma knife radiosurgery. The patient was pain free 2 months after GKS. Contrast cisternography with CT scanning is an excellent alternative imaging modality for the treatment of patients with intractable trigeminal neuralgia who are unable to undergo MR imaging.The authors describe acute deterioration in facial and acoustic neuropathies following radiosurgery for acoustic neuromas. In May 1995, a 26-year-old man, who had no evidence of neurofibromatosis Type 2, was treated with gamma knife radiosurgery (GKS; maximum dose 20 Gy and margin dose 14 Gy) for a right-sided intracanalicular acoustic tumor. Two days after the treatment, he developed headache, vomiting, right-sided facial weakness, tinnitus, and right hearing loss. There was a deterioration of facial nerve function and hearing function from pretreatment values. The facial function worsened from House-Brackmann Grade 1 to 3. Hearing deteriorated from Grade 1 to 5. Magnetic resonance (MR) images, obtained at the same time revealed an obvious decrease in contrast enhancement of the tumor without any change in tumor size or peritumoral edema. Facial nerve function improved gradually and increased to House-Brackmann Grade 2 by 8 months post-GKS. The tumor has been unchanged in size for 5 years, and facial nerve function has also been maintained at Grade 2 with unchanged deafness. This is the first detailed report of immediate facial neuropathy after GKS for acoustic neuroma and MR imaging revealing early possibly toxic changes. Potential explanations for this phenomenon are presented.In clinical follow-up studies after radiosurgery, imaging modalities such as computerized tomography (CT) and magnetic resonance (MR) imaging are used. Accurate determination of the residual lesion volume is necessary for realistic assessment of the effects of treatment. Usually, the diameters rather than the volume of the lesion are measured. To determine the lesion volume without using stereotactically defined images, the software program VOLUMESERIES has been developed. VOLUMESERIES is a personal computer-based image analysis tool. Acquired DICOM CT scans and MR image series can be visualized. The region of interest is contoured with the help of the mouse, and then the system calculates the volume of the contoured region and the total volume is given in cubic centimeters. The defined volume is also displayed in reconstructed sagittal and coronal slices. In addition, distance measurements can be performed to measure tumor extent. The accuracy of VOLUMESERIES was checked against stereotactically defined images in the Leksell GammaPlan treatment planning program. A discrepancy in target volumes of approximately 8% was observed between the two methods. This discrepancy is of lesser interest because the method is used to determine the course of the target volume over time, rather than the absolute volume. Moreover, it could be shown that the method was more sensitive than the tumor diameter measurements currently in use. VOLUMESERIES appears to be a valuable tool for assessing residual lesion volume on follow-up images after gamma knife radiosurgery while avoiding the need for stereotactic definition.This study was conducted to evaluate the geometric distortion of angiographic images created from a commonly used digital x-ray imaging system and the performance of a commercially available distortion-correction computer program. A 12 x 12 x 12-cm wood phantom was constructed. Lead shots, 2 mm in diameter, were attached to the surfaces of the phantom. The phantom was then placed inside the angiographic localizer. Cut films (frontal and lateral analog films) of the phantom were obtained. The films were analyzed using GammaPlan target series 4.12. The same procedure was repeated with a digital x-ray imaging system equipped with a computer program to correct the geometric distortion. The distortion of the two sets of digital images was evaluated using the coordinates of the lead shots from the cut films as references. The coordinates of all lead shots obtained from digital images and corrected by the computer program coincided within 0.5 mm of those obtained from cut films. The average difference is 0.28 mm with a standard deviation of 0.01 mm. On the other hand, the coordinates obtained from digital images with and without correction can differ by as much as 3.4 mm. The average difference is 1.53 mm, with a standard deviation of 0.67 mm. The investigated computer program can reduce the geometric distortion of digital images from a commonly used x-ray imaging system to less than 0.5 mm. Therefore, they are suitable for the localization of arteriovenous malformations and other vascular targets in gamma knife radiosurgery.

Outcome following intrastriatal fetal mesencephalic grafts for Parkinson's patients is directly related to the volume of grafted tissue

The effect of varying the volume of grafted fetal mesencephalic tissue was studied in patients with idiopathic Parkinsons disease in a single-blinded study. Evaluations were performed according to the Core Assessment Program for Intracerebral Transplantation and videotaped both prior to transplantation and in 3-month intervals after transplantation. One group, low-volume grafts (six subjects; mean age, 57.2 years), received ventral mesencephalon grafts from one to two donors with an approximate volume up to 20 mm3, while the second group, high-volume grafts (seven subjects; mean age, 59.5 years), received ventral mesencephalon grafts from three or more donors with an approximate volume of 24 mm3. Both groups of patients demonstrated significant improvement over presurgical baseline scores on all major parameters. The high-volume group had significantly greater improvements on all the UPDRS scores and also better performance on a variety of motor performance tasks over that seen among low-volume patients. These results indicate that variations of fetal graft volume do have an impact on clinical outcome.

In vivo magnetic resonance spectroscopy of human fetal neural transplants.

To better define the survival and cellular composition of human fetal neurotransplants in vivo, we performed quantitative 1H MRS to determine the concentration of the neuronal amino acid [N‐acetylaspartate] within MRI‐visible grafts. In all, 71 grafts in 38 patients [24 Parkinsons disease (PD), 14 Huntingtons disease (HD)] were examined, as well as 24 untreated PD and HD patients and 13 age‐matched normal controls. MRI appearances of edema were present in three out of 71 grafts, the remainder being consistent with histologically identified viable neural transplant tissue. N‐acetylaspartate (NAA), creatine, choline, myoinositol and glutamine plus glutamate (Glx) were identified in all post‐transplant putamens, with abnormal metabolites, lactate and/or lipid detectable in only three patients. Of 71 grafts, 19 occupied more than 60% of the MRS‐examined volume (VOI) (mean 84.2 ± 3%; range 61–100%). In those, [NAA] was 8.50 ± 0.99 mM in eight PD spectra and 6.59 ± 0.81 mM in 11 HD spectra, and was not significantly different from controls. In contrast, transplanted fetal neurones contain less than 0.4 mM of the neuronal amino acid NAA. This suggests that established fetal neurotransplants in the human putamen of both PD and HD patients are populated by adult neurones, axons and dendrites. Copyright

Outcomes and Complications of Fetal Tissue Transplantation in Parkinson’s Disease

This study was undertaken to investigate the outcomes, complication rates and risk factors of stereotactic intrastriatal neurotransplantation for Parkinson’s disease (PD). Bilateral stereotactic neurotransplantation was performed (as previously described) in 60 patients with idiopathic PD. Clinical outcome was evaluated using the Unified Parkinson’s Disease Rating Scale (UPDRS). The incidence of complication was evaluated by retrospective analysis of the clinical outcomes of the transplanted patients. Patients demonstrated significant improvement in UPDRS scores 12 months after transplantation. Nine patients experienced adverse effects after neurotransplantation, 3 requiring surgical intervention. Patients showed a significant overall improvement and no greater incidence of risk than that of other intracranial procedures.

Activation of Neurotransplants in Humans

Clinical studies report symptomatic benefit in most fetal neurotransplantation treated Parkinsons disease patients. The underlying mechanism is incompletely explained. We investigated whether neural connections between host and transplanted tissue are established. Two Parkinsons disease patients with clinically excellent outcome after transplantation were studied with functional magnetic resonance imaging. A repetitive motor task that provided robust stimulation in the contralateral putamen in volunteers activated graft bearing regions of putamen in patients. In response to contralateral motor tasks, activation was recorded consistently in left putamen in patient 1 and in right putamen in patient 2. Functional magnetic resonance imaging suggests that neuronal rewiring contributes to the functioning of neurotransplants in vivo in humans.

Use of Posteroventral Pallidotomy for Treatment of Parkinson’s Disease: Is Pallidotomy Still an Experimental Procedure?

Surgical interventions have been employed to alleviate symptoms of Parkinson’s disease (PD) for decades, with improving success. One such treatment has been pallidotomy, the lesioning of a portion of the globus pallidus. Early pallidotomy procedures have paved the way for more accurately targeted methods. Technological advancements in imaging and targeting have made modern pallidotomy a safe and well-tested means of treating PD patients that has reliably positive results. Numerous group studies in recent years have demonstrated effective relief of PD symptoms, and the neuroanatomical and physiological aspects which underlie its effects are being elucidated as well. Recent descriptions of pallidotomy as an experimental procedure must therefore be considered in light of these reports. This review will examine the development of the pallidotomy procedure and the neuroanatomical rationale which underlies it, and discuss recent studies of its efficacy in PD patients.

Transplantation of Human Neural Progenitor Cells Reveals Structural and Functional Improvements in the Spastic Han-Wistar Rat Model of Ataxia:

The use of regenerative medicine to treat nervous system disorders like ataxia has been proposed to either replace or support degenerating neurons. In this study, we assessed the ability of human neural progenitor cells (hNPCs) to repair and restore the function of dying neurons within the spastic Han-Wistar rat (sHW), a model of ataxia. The sHW rat suffers from neurodegeneration of specific neurons, including cerebellar Purkinje cells and hippocampal CA3 pyramidal cells leading to the observed symptoms of forelimb tremor, hind-leg rigidity, gait abnormality, motor incoordination, and a shortened life span. To alleviate the symptoms of neurodegeneration and to replace or augment dying neurons, neuronal human progenitor cells were implanted into the sHW rats. At 30 d of age, male sHW mutant rats underwent subcutaneous implantation of an Alzet osmotic pump that infused cyclosporine (15 mg/kg/d) used to suppress the rat’s immune system. At 40 d, sHW rats received bilateral injections (500,000 cells in 5 µL media) of live hNPCs, dead hNPCs, live human embryonic kidney cells, or growth media either into the cerebellar cortex or into the hippocampus. To monitor results, motor activity scores (open-field testing) and weights of the animals were recorded weekly. The sHW rats that received hNPC transplantation into the cerebellum, at 60 d of age, displayed significantly higher motor activity scores and sustained greater weights and longevities than control-treated sHW rats or any hippocampal treatment group. In addition, cerebellar histology revealed that the transplanted hNPCs displayed signs of migration and signs of neuronal development in the degenerated Purkinje cell layer. This study revealed that implanted human progenitor cells reduced the ataxic symptoms in the sHW rat, identifying a future clinical use of these progenitor cells against ataxia and associated neurodegenerative diseases.