Imaging beyond the striatonigral dopaminergic system in Parkinson's disease

Parkinson 's disease (PD) is characterized by progressive loss of dopaminergic neurons in the nigrostriatal pathway, but this seems to constitute only part of the whole pathological process of the disease. Accumulating data have documented the concomitant degeneration of other dopaminergic pathways and of the serotonergic, cholinergic and noradrenergic neurotransmitter systems. In addition, pathologic process is not only restricted in the brain, since the spinal cord and the peripheral autonomic nervous system are also affected. The pathogenesis of PD remains unclear. The use of positron emission tomography and single photon emission tomography may contribute to the understanding of these aspects of the disease. This review will discuss the role of PET and SPET in imaging the extrastriatal dopaminergic system and other neurotransmitter systems as well as the imaging of microglial activation and cardiac sympathetic denervation in PD. In conclusion, several PET and SPET ligands can detect changes in extrastriatal dopaminergic system as well as in the serotonergic, cholinergic and noradrenergic systems in PD and also explore its possible correlation with motor and non motor symptoms. The use of PET scintigraphy allows the detection of microglial activation in PD, while (123)I-MIBG scintigraphy depicts cardiac sympathetic denervation in PD and is a useful imaging tool for differentiating PD from other types of parkinsonism.

Lack of association between CX3CR1 V249I and T280M polymorphisms and risk of Parkinson's disease in a Greek population

Mechanisms that mediate inflammatory responses may be crucial in Parkinson's disease (PD) pathogenesis. In the brain, the chemokine receptor CX3CR1 is exclusively expressed in microglia, selectively mediating microglia-neuron interaction in response to its ligand, the chemokine fractalkine. Two functional single nucleotide polymorphisms, V249I and T280M, in the coding sequence of the CX3CR1 receptor have been found to alter ligand-receptor affinity. The aim of this study was to investigate the genetic role of CX3CR1 in sporadic PD. We examined the V249I and T280M CX3CR1 polymorphisms in a case-control study of 176 sporadic PD patients and 115 controls. Polymerase chain reaction-restriction fragment length polymorphism analysis was performed for the detection of the studied CX3CR1 genotypes. This is the first study that tests CX3CR1 gene polymorphisms in patients with PD. We found no differences in genotype or haplotype frequencies between PD patients and controls, suggesting that CX3CR1 V249I and T280M polymorphisms do not increase susceptibility to PD. Additional studies should further investigate the CX3CL1-CX3CR1 axis in PD.

Pharmacological treatment and the prospect of pharmacogenetics in Parkinson's disease

Parkinson disease (PD) is a progressive movement disorder marked by tremor, rigidity, bradykinesia and postural instability. Levodopa (l-dopa), usually combined with a peripheral dopa decarboxylase inhibitor, has been proved to provide the best symptomatic benefit for PD. However, its long-term efficacy is limited because of motor complications and drug-induced dyskinesia. Dopamine agonists, catechol-O-methyltransferase inhibitors and monoamine oxidase-B inhibitors are anti-parkinsonian (anti-PD) drugs that have been found to further improve the potency of l-dopa and prevent the onset of motor complications. However, as PD is a progressive disorder, all the drugs used for its therapy, manifest reduced efficacy and adverse effects with time. Research on the field of pharmacogenetics has pointed out that the genetic variability of each individual determines to a large extent the inter-individual variability in response to anti-PD drugs. Clinicogenetic trials show that drug efficacy or toxicity or susceptibility to side effects are features governed by genetic principles. This article is a review of the present pharmacological treatment of PD and current pharmacogenetic data for PD.

Pupillometry and 123I-DaTSCAN imaging in Parkinson's disease: a comparison study

The purpose of this study was the evaluation of pupil light reflex (PLR) in patients with Parkinson's disease (PD) by using a modern pupillometry system and the investigation of its potential relationship with dopamine transporter imaging (DaTSCAN), which is an objective method for the evaluation of presynaptic dopaminergic system. PLR was evaluated using pupillometry in 35 patients with PD without clinical evidence of autonomic dysfunction and 44 healthy matched controls. PLR was elicited using a fully automated pupillometry system and six parameters were measured. Dopamine transporter imaging was performed using radioactive ioflupane (123)I-FP-CIT [(123)I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)-nortropane]. A significant increase in latency and a significant decrease in amplitude, maximum constriction velocity, as well as maximum acceleration were observed in PD patients. There was no significant difference in initial radius and minimum radius values. Investigating the relationship between pupillometry parameters and (123)I-FP-CIT binding values, we correlated values from the semiquantitative analysis of radioligand uptake with pupillometry parameters, but we found no significant correlation. This study demonstrates PLR impairment in patients with PD without overt autonomic dysfunction. This impairment does not seem to correspond to the reduction of radioligand binding in the striatum as the result of presynaptic dopaminergic dysfunction, suggesting a different deterioration rate of these systems.

GSK3β polymorphisms, MAPT H1 haplotype and Parkinson's disease in a Greek cohort

To determine whether polymorphisms in the microtubule-associated protein tau (MAPT) and/or glycogen synthase kinase-3β (GSK3β) genes underpin susceptibility to Parkinson's disease (PD), we conducted a case-control association study in a Greek cohort of 196 PD cases and 163 healthy controls. In our study, the MAPT H1 haplotype was found to be significantly associated with PD, no association was detected between the intronic rs6438552 (-157 T/C) GSK3β polymorphism and PD, whereas the C/C genotype of the promoter rs334558 (-50 T/C) GSK3β polymorphism was found to exert a protective role. The C/C genotype of the rs334558 GSK3β polymorphism was also found to have an additional protective role in our MAPT H1/H1 PD subgroup. Haplotype analysis revealed that, the T-T haplotype of both GSK3β polymorphisms was over-represented in PD patients compared to controls, and this association was independent of MAPT H1 haplotype.

Reversible parkinsonism due to chronic bilateral subdural hematomas

Subdural hematoma is a rare cause of secondary parkinsonism. We report a 65-year-old woman with reversible parkinsonism due to bilateral chronic subdural hematomas. Symmetrical parkinsonism evolved acutely 45 days after a trivial head injury. Mild pyramidal signs were also present on her left side. MRI revealed bilateral chronic subdural hematomas. The patient's parkinsonism was completely abolished one month after successful neurosurgical evacuation of the hematomas.

[Molecular imaging of cerebral blood flow and metabolism with SPET and PET in principal dementias]

In this review article the significance of molecular imaging techniques, single photon emission tomography and positron emission tomography (SPET and PET), in the diagnosis and differential diagnosis of various types of dementia is described. A major part of this article is focused on molecular imaging in Alzheimer's disease where parietal, temporal and posterior cingulate cortex hypoperfusion and hypometabolism are the predominant findings in molecular imaging modalities. In cases of mild amnestic cognitive impairment, molecular SPET imaging can differentiate patients converting to Alzheimer's disease from non converters. Molecular SPET imaging with pre-synaptic dopamine receptors radioligand ((123)I-ioflupane or DaTSCAN), is the method of choice in order to differentiate Alzheimer's disease from Lewy body dementia. Finally, nuclear medicine procedures support the diagnosis in fronto-temporal and multi-infarct dementia.

Personality profile of patients with juvenile myoclonic epilepsy

In the study described here we attempted to evaluate the personality profiles of 25 patients with juvenile myoclonic epilepsy (JME) at the time of diagnosis, before treatment, and to explore a potential relationship between behavioral aspects and clinical outcome. For this purpose we employed a standardized and objective instrument, the Minnesota Multiphasic Personality Inventory (MMPI), and found that patients with JME have a personality profile similar to that of the control group, which corresponds to the 3,1 code type MMPI profile. We also noted that the characteristics of this personality type include those described in patients with long-duration JME by previous researchers. Consequently, we conclude that personality aberrations are not a feature of this syndrome. Furthermore, we observed that under treatment, EEGs normalized in patients who had exhibited "psychotic tendencies" pretreatment. The credibility of our results is supported by the fact that assessment of the personality profile was not confounded by medication or the longitudinal burden of epileptic seizures.

(123)I-FP-CIT SPET striatal uptake in parkinsonian patients with the alpha-synuclein (G209A) mutation A

Autosomal dominant familial Parkinson's disease (PD) due to the alpha-synuclein (G209A) mutation shares similar clinical characteristics with sporadic PD. Pathological studies however indicate more widespread neuronal degeneration in the familial form. We performed (123)I-FP-CIT SPET (DaTSCAN) study in nine patients with familial PD carrying the alpha-synuclein (G209A) mutation and fifteen matched patients with sporadic disease. Both groups had equal radioligand reduction uptake in the striatum but the alpha-synuclein patients showed less asymmetry and increased putamen to caudate ratio. Our findings indicate that there are minor differences in DAT SPET parameters between alpha-synuclein and sporadic PD patients insufficient to provide differential diagnosis.

Mutation analysis of the PINK1 gene in 391 patients with Parkinson disease

OBJECTIVES

To determine the frequency, distribution, and clinical features of Parkinson disease (PD) with PINK1 mutations.

DESIGN

Retrospective clinical and genetic review.

SETTING

University hospital.

PATIENTS

We performed extensive mutation analyses of PINK1 in 414 PD patients negative for parkin mutations (mean [SD] age at onset, 42.8 [14.3] years), including 391 unrelated patients (190 patients with sporadic PD and 201 probands of patients with familial PD) from 13 countries.

RESULTS

We found 10 patients with PD from 9 families with PINK1 mutations and identified 7 novel mutations (2 homozygous mutations [p.D297MfsX22 and p.W437R] and 5 single heterozygous mutations [p.A78V, p.P196QfsX25, p.M342V, p.W437R, and p.N542S]). No compound heterozygous mutations were found. The frequency of homozygous mutations was 4.26% (2 of 47) in families with autosomal recessive PD and 0.53% (1 of 190) in patients with sporadic PD. The frequency of heterozygous mutations was 1.89% (2 of 106) in families with potential autosomal dominant PD and 1.05% (2 of 190) in patients with sporadic PD. The mean (SD) age at onset in patients with single heterozygous mutations (53.6 [11.1] years; range, 39-69 years) was higher than that in patients with homozygous mutations (34.0 [20.3] years; range, 10-55 years). Myocardial iodine-123 metaiodobenzylguanidine uptake was low in patients with heterozygous mutations but not in those with homozygous mutations.

CONCLUSIONS

Our results suggest that homozygous PINK1 mutations tend to be diagnosed as the early-onset autosomal recessive form of PD. Single heterozygous mutations may contribute to the development of sporadic PD and also could be an additional genetic predisposition for developing familial PD. The reduced myocardial iodine-123 metaiodobenzylguanidine uptake observed in patients with single heterozygous PINK1 mutations is similar to that seen in patients with sporadic PD.

[Immune factors or depression? Fatigue correlates in Parkinson's disease]

INTRODUCTION

Fatigue is a frequent symptom in Parkinson disease (PD), but its pathogenesis remains obscure. Fatigue may be influenced by depression and motor disability, but immunological factors have been also implicated. The purpose of the study was to assess fatigue in PD patients in relation to depression and various immunological factors.

SUBJECTS AND METHODS

Forty PD patients and 26 normal matched controls were studied. Fatigue was assessed by the Fatigue Severity Scale (FSS). The Beck Depression Inventory (BDI) was employed for depression screening. The following immunological factors were estimated: a) T- and B-lymphocytes, T-lymphocyte subsets (helper/suppressor cells) as well as natural killer cells (NK); b) circulating levels of interleukins IL-1alpha, IL-1beta, IL-6, IL-1 receptor antagonist (IL-1Ra) and tumor necrosis factor-alpha.

RESULTS

FSS mean score was higher in PD patients compared to controls (p < 0.01). Significant differences between patients and controls were found in the following immunological parameters. In PD patients: a) mean percentage of NK cells was higher, p < 0.01); b) IL-1beta levels were significantly increased (p < 0.01) and IL-1Ra levels were decreased (p < 0.001). FSS correlated significantly to BDI (p < 0.008). Circulating Il-1Ra levels correlated to fatigue severity (p < 0.01), but after exclusion of depressed PD subjects this correlation significance level dropped to p = 0.055.

CONCLUSIONS

Our results indicate that fatigue is a common non motor symptom in PD. Immunological differences between PD patients and controls were observed in percentages of NK cells, IL-1beta and IL-1Ra blood levels. Fatigue correlated to depression and IL-Ra levels. However after exclusion of depressed subjects IL-1Ra levels showed only a tendency to significance, leaving depression as the principle correlate of fatigue.

The G2019S LRRK2 mutation is uncommon amongst Greek patients with sporadic Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder affecting approximately 2% of the population >60 years of age. Although, the etiology of PD is still unknown, the genetic background of the disease has been documented. Recently, a mutation in the LRRK2 gene, G2019S, was associated with 3-41% and 1-2% of familial and sporadic PD, respectively suggesting a pivotal role of LRRK2 in PD. In this report, we examine the association of the G2019S mutation with sporadic late-onset PD, in an independent cohort of Greek patients and controls.

Association of the Tau haplotype with Parkinson's disease in the Greek population

We compared the distribution of the Tau H1 haplotype and related subhaplotypes in a group of clinically diagnosed Parkinson's disease patients (n = 133) and in control individuals (n = 113) from northern Greece. We were able to detect a statistically significant overrepresentation of the H1H1 genotype in our patient group (OR for H1H1 vs. H1H2 and H2H2: 1.73; 95% CI: 1.03-2.90; P = 0.037). The H1 subhaplotype significantly associated with the disease in our population was different from the one previously reported for a Norwegian population, suggesting that the nature of the association of Tau with Parkinson's disease is influenced by ethnic variation.

Relapsing hemiparkinsonism due to recurrent meningioma

We describe a case with left hemiparkinsonism due to a parasagittal meningioma with surrounding edema compressing the right basal ganglia. The patient was successfully operated and his symptoms resolved completely. However 7 years later his hemiparkinsonism reappeared due to a relapse of the right parasagittal meningioma. This rare case points to the significance of neuroimaging in the evaluation of parkinsonism.

Superficial siderosis of the CNS: Report of three cases and review of the literature

Superficial siderosis (SS) is a rare entity. A chronic subarachnoid hemorrhage (SAH) leads to the deposition of ferric pigments and ions in the surface of the central nervous system (CNS). The cause of this hemorrhage is identified in half of the cases. The disease progresses slowly and the damage is often irreversible by the time diagnosis is established. The management focuses on the identification and ablation of the bleeding source. Knowledge about this entity is based on sporadic reports. We describe three cases of superficial siderosis and briefly review the literature.

Endothelial function markers in parkinsonian patients with hyperhomocysteinemia

Hyperhomocysteinemia is considered a risk factor for vascular disease causing endothelial damage and consequently atherogenesis. The purpose of this study was to investigate the effect of elevated homocysteine on certain biochemical markers of endothelial function in patients with idiopathic Parkinson's disease (PD). Blood homocysteine levels were assessed in 57 PD patients and 40 matched normal controls. Investigation of the C677T 5,10 methylenetetrahydrofolate reductase (MTHFR) genotype was also performed in 43 PD patients. The following markers of endothelial function were assessed: superoxide dismutase (SOD), nitric oxide (NO), sICAM-1 and sE-selectin. Homocysteine levels were found mildly elevated in PD patients particularly in those treated with L-Dopa. MTHFR genotype did not influence significantly this finding. SOD activity was found reduced but it was not correlated to homocysteine levels. All other parameters measured were normal and were not related to hyperhomocysteinemia. Our findings indicate that mild hyperhomocysteinemia in PD patients was not associated with endothelial dysfunction.