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author:("joutna, judo")
1.  Long-term test–retest reliability of striatal and extrastriatal dopamine D2/3 receptor binding: study with [11C]raclopride and high-resolution PET 
We measured the long-term test–retest reliability of [11C]raclopride binding in striatal subregions, the thalamus and the cortex using the bolus-plus-infusion method and a high-resolution positron emission scanner. Seven healthy male volunteers underwent two positron emission tomography (PET) [11C]raclopride assessments, with a 5-week retest interval. D2/3 receptor availability was quantified as binding potential using the simplified reference tissue model. Absolute variability (VAR) and intraclass correlation coefficient (ICC) values indicated very good reproducibility for the striatum and were 4.5%/0.82, 3.9%/0.83, and 3.9%/0.82, for the caudate nucleus, putamen, and ventral striatum, respectively. Thalamic reliability was also very good, with VAR of 3.7% and ICC of 0.92. Test–retest data for cortical areas showed good to moderate reproducibility (6.1% to 13.1%). Our results are in line with previous test–retest studies of [11C]raclopride binding in the striatum. A novel finding is the relatively low variability of [11C]raclopride binding, providing suggestive evidence that extrastriatal D2/3 binding can be studied in vivo with [11C]raclopride PET to be verified in future studies.
PMCID: PMC4640276  PMID: 25853904
cortical mapping; dopamine; PET; test–retest; [11C]raclopride
2.  Recurrent paraparesis and death of a patient with ‘whippet’ abuse 
Oxford Medical Case Reports  2016;2016(3):41-43.
Nitrous oxide is increasingly used as a recreational drug that is easily and legally available worldwide. Occasional nitrous oxide use has been considered relatively safe without the development of addiction or major adverse effects. However, heavy long-term nitrous oxide abuse can be associated with severe neurological complications, and even deaths have been described. The characteristic presentation is myeloneuropathy with dorsal column degeneration and demyelinating sensory polyneuropathy related to vitamin B12 deficiency. Described is a 23-year-old male who developed recurrent paraparesis related to nitrous oxide abuse. A second, more severe, episode of paraparesis was associated with predominantly lower motor neuron damage. A partial recovery was achieved by discontinuation of nitrous oxide use and initiation of vitamin B12 supplementation. However, the patient relapsed and ultimately died while being intoxicated with several abusive substances. The case adds to the cumulative literature about the clinical phenomenology and dangers of nitrous oxide abuse.
PMCID: PMC4794556  PMID: 26989492
3.  Hypermetabolism of Olivary Nuclei in a Patient with Progressive Ataxia and Palatal Tremor 
The pathophysiology of the movement disorder progressive ataxia with palatal tremor (PAPT) is unclear.
Case report
A 77-year-old male presented with dysarthria, ataxia, and 1–2 Hz palatal tremor. A diagnosis of probable sporadic PAPT was established. Brain magnetic resonance imaging was normal at the presymptomatic phase but later showed olivary hypertrophy. Brain [18F]-fludeoxyglucose (FDG) positron emission tomography (PET) showed bilateral hypermetabolism in the olivary nuclei.
This second reported patient with PAPT and FDG-PET shows that olivary hypertrophy is paralleled with hypermetabolism. The olivary nuclei pathology also appears to be temporally associated with symptom onset.
PMCID: PMC4557084  PMID: 26339529
Palatal tremor; ataxia; olivary nuclei; positron emission tomography
4.  Akinetic Crisis in Parkinson's Disease Is Associated with a Severe Loss of Striatal Dopamine Transporter Function: A Report of Two Cases 
Case Reports in Neurology  2014;6(3):275-280.
Akinetic crisis or acute akinesia is a life-threatening complication of Parkinson's disease (PD) with unknown pathophysiological mechanisms. Clinically, it resembles the neuroleptic malignant syndrome, and dopaminergic drugs are transiently ineffective in the acute phase of the condition. There are no published dopaminergic functional imaging studies on PD patients with akinetic crisis. Here we report 2 advanced PD patients with akinetic crisis who were scanned with SPECT using brain dopamine transporter ligand [123I]FP-CIT. The first patient was additionally scanned before the condition developed, and the second patient was scanned after recovery. Striatal dopamine transporter binding was lower during than before the crisis, and both patients showed a nearly complete loss of dopamine transporter binding during the crisis. Serial imaging showed that the uptake remained negligible despite an improvement in motor function after recovery. Akinetic crisis in PD appears to be associated with a particularly severe loss of presynaptic striatal dopamine function that does not improve after recovery. Apart from presynaptic dopaminergic function, other dopaminergic or nondopaminergic mechanisms are involved in the clinical improvement of motor functions after akinetic crisis in PD.
PMCID: PMC4280458  PMID: 25566059
Parkinson's disease; Dopamine transporter; SPECT; Akinesia
5.  Striatal volume is related to phonemic verbal fluency but not to semantic or alternating verbal fluency in early Parkinson’s disease 
Journal of Neural Transmission  2013;121(1):33-40.
Verbal fluency impairments are frequent in Parkinson’s disease (PD) and they may be present already at early stages. Semantic fluency impairment is associated with Parkinson’s disease dementia and temporal, frontal and cerebellar cortical changes. Few studies have addressed cerebral structural correlates of different verbal fluency tasks in early stage PD. We therefore studied gray matter volumes of T1-weighted MRI images using voxel-based morphometry in relation to semantic, phonemic, and alternating verbal fluency in younger (mean age <65 years), early stage (mean disease duration <3 years), non-demented PD patients (n = 28) and healthy controls (n = 27). We found a significant association between worse phonemic fluency and smaller striatal, namely right caudate gray matter volume in the PD group only (family-wise error corrected p = 0.007). Reduced semantic fluency was associated with smaller gray matter volumes in left parietal cortex (p = 0.037) and at trend level with smaller bilateral cerebellum gray matter volume across groups (p = 0.062), but not in the separate PD or control groups. There were no significant relationships between alternating fluency and gray matter volumes in the whole sample or in the groups separately. The fact that phonemic fluency, but not semantic or alternating fluency, was associated with caudate gray matter volume at early stage PD suggests that different fluency tasks rely on different neural substrates, and that language networks supporting semantic search and verbal-semantic switching are unrelated to brain gray matter volume at early disease stages in PD.
PMCID: PMC3889690  PMID: 23913130
Early stage Parkinson’s disease; Voxel-based morphometry; Verbal fluency; Semantic fluency; Phonemic fluency; Alternating fluency
6.  Parallel Appearance of Compulsive Behaviors and Artistic Creativity in Parkinson's Disease 
Case Reports in Neurology  2012;4(1):77-83.
A 55-year-old male with idiopathic Parkinson's disease developed three behavioral changes under combination therapy with selegiline, cabergoline and levodopa. Co-existent behaviors included severe pathological gambling, punding and novel skills in writing poetry (published poetry books). Brain [18F]fluorodopa PET imaging showed decreased tracer uptake in the striatum contralateral to the predominant motor symptoms, consistent with the clinical diagnosis of Parkinson's disease. Uptake in the ventral striatum was markedly high. Brain MRI before and after behavioral changes showed no pathological findings. The patient was diagnosed as having Parkinson's disease together with DSM-IV criteria-fulfilling pathological gambling and punding-like stereotyped behavior. There are no established criteria for the classification of emerged artistic creativity, although there are descriptions of the phenomenon in the literature. Inspired by the case, we conducted a preliminary survey – including 290 patients with Parkinson's disease – exploring the possible relationship between creativity and impulsive-compulsive behaviors. The case, supported by the results of the survey, adds to the cumulative evidence of the association between dopaminergic medication and enhanced creativity, and suggests a possible linkage between increased artistic creativity and impulsive-compulsive behaviors in Parkinson's disease. Furthermore, it could be speculated that the high mesolimbic dopamine function might relate to the behavioral changes observed in this patient, and is suggestive of the overlapping neurobiological mechanisms of compulsive behaviors and artistic creativity.
PMCID: PMC3369413  PMID: 22679432
Parkinson's disease; Impulse control disorder; Gambling; Punding; Mesolimbic; Dopamine; Ventral striatum; Creativity

Results 1-6 (6)