Biomedical subjects

Timo Kurki

Publications and source records attributed to Timo Kurki.

16 recordsLinked to original sources

PubMed2006

MRI findings and Axis I and II psychiatric disorders after traumatic brain injury: a 30-year retrospective follow-up study.

We studied the association between psychiatric disorders and the presence and location of traumatic lesions on magnetic resonance imaging (MRI) in 58 patients, on average, 30 years after traumatic brain injury. Axis I psychiatric disorders that had begun after the injury were assessed with the Schedules for Clinical Assessment in Neuropsychiatry (version 2.1), and Axis II disorders with the Structured Clinical Interview for DSM-III-R Personality Disorders. A 1.5-Tesla MRI scanner was used. One-third of the subjects had traumatic lesions visible on MRI. Only three psychiatric disorders, that is, delusional disorder, dementia, and the disinhibited type of organic personality syndrome, were significantly more common in subjects with contusions. Concerning the location of contusions, organic personality syndrome and its disinhibited subtype were associated with frontal lesions, and major depression was, surprisingly, inversely associated with temporal lesions. These results, which should be interpreted with caution due to the limited size of the study group, suggest that the majority of psychiatric disorders after traumatic brain injury are not closely related to the specific location or even the presence of contusions detectable with post-acute MRI.

Adult↗

PubMed2006

MR imaging of head trauma: visibility of contusions and other intraparenchymal injuries in early and late stage.

The aim of this study was to investigate the visibility of traumatic brain lesions on conventional magnetic resonance images (MRI) in early and late phase. Thirty-six patients were studied 1 week and 1 year after a traumatic brain injury. A similar MRI technique was used in both studies; T2-weighted fast or turbo spin echo images, fluid attenuated inversion recovery (FLAIR) images and T1-weighted images were used for analysis. The number and extent of contusions and semi-quantitative score of other traumatic intraparenchymal lesions were compared in the early and late phase. Contusions were seen in 18 patients both in acute and 1 year MRI; the number and extent of visible contusions was significantly decreased at 1 year. Other traumatic intraparenchymal lesions were detected in 12 patients in early MRI and in 10 patients in late MRI. The number of visible lesions and the semi-quantitative scores were significantly lower at 1 year. There is a significant decrease in the visibility of both cortical contusions and other intraparenchymal injuries in late MRI studies compared with studies in acute stage using conventional imaging techniques. Thus, early phase MRI is essential for the detection of brain injury at least using conventional imaging techniques.

Accidental Falls↗

PubMed2005

Cognitive functions in relation to MRI findings 30 years after traumatic brain injury.

OBJECTIVE: The aim of the study was to relate cognitive effects of a remote traumatic brain injury (TBI) to MRI findings and severity of injury. METHOD: Sixty-one patients were assessed on average 30 years after a TBI of variable severity. A comprehensive cognitive test battery was used to evaluate memory, executive functions and cognitive overall impairment. Multiple regression analyses were used to examine the relationships between cognitive variables and MRI volumetric findings (the volumes of the hippocampus and the lateral ventricles) and local contusions on MRI. Also, the effect of injury severity on cognitive outcome was evaluated. RESULTS: Reductions in hippocampal volumes and lateral ventricular enlargement were significantly associated with impaired memory functions, memory complaints and executive functions. Of the MRI parameters used, the best predictor for cognitive outcome was the volume of the lateral ventricle. There was only a modest relationship between severity of injury and cognitive performance. CONCLUSIONS: The results show that long-term memory impairments after TBI are associated with MRI volumetric measures. This suggests that the degree of diffuse injury leading to atrophic changes is prognostically more important than the initial severity of TBI.

Adult↗

PubMed2005

Successful pregnancy of a patient with Balo's concentric sclerosis.

Balo's concentric sclerosis is a severe demyelinating disease with poor prognosis. To date, nothing is known about the effects of pregnancy on the course of Balo's disease. We describe here the first successful pregnancy of a patient with Balo's concentric sclerosis. Upon neurological worsenings during pregnancy, our patient was treated with high-dose methylprednisolone and plasma-exchange. Intravenous immunoglobulin and interferon-beta-1a were given postpartum. At the last follow-up visit 2.5 years after the delivery the patient had only minor residual symptoms.

Adult↗

PubMed2005

Riedel's thyroiditis in a patient with multiple sclerosis.

Our patient developed Riedel's thyroiditis soon after having an exacerbation of multiple sclerosis (MS). MS has been associated with other autoimmune diseases, including thyroiditis, and both Hashimoto's thyroiditis and subacute thyroiditis have been described in connection with MS. Yet, we are not aware of any other patient reported to have concomitant MS and Riedel's thyroiditis. The association between MS and Riedel's thyroiditis remains obscure but may reflect an autoimmune disorder common to both diseases.

Adult↗

PubMed2004

Volumes of the caudate nuclei in women with somatization disorder and healthy women.

Very little is known about the pathophysiology of somatization disorder. This study was designed to analyze the volumes of some brain structures possibly involved in somatization based on the observation of glucose metabolism of the brain in these patients. We studied 10 female patients with a diagnosis of somatization disorder or undifferentiated somatoform disorder with no comorbid current DSM-IV Axis I disorder and compared them to 16 healthy female volunteers using brain MRI (1.5 T instrument). The patients had bilateral enlargement of caudate nuclei volumes compared with healthy volunteers. These volume differences in the caudate nuclei could be associated with the pathophysiology of somatization.

Adult↗

PubMed2004

Positron emission tomography examination of cerebral blood flow and glucose metabolism in young CADASIL patients.

BACKGROUND AND PURPOSE: CADASIL causes repeated ischemic strokes leading to subcortical vascular dementia. The purpose of this study was to assess whether cerebral blood flow (CBF) and regional cerebral metabolic rates of glucose (rCMR(gluc)) in CADASIL patients are affected in early adulthood. METHODS: CBF and rCMR(gluc) were examined with positron emission tomography in correlation with magnetic resonance imaging (MRI) in 14 adult (19 to 41 years) CADASIL patients with the Notch3 R133C mutation. Seven patients had experienced transient ischemic attack and 3 had experienced > or =1 strokes. RESULTS: The mean CBF in the CADASIL patients was significantly lower in both frontal (P=0.019) and occipital (P=0.009) white matter (WM) than those in the controls. CBF decreased significantly with increased severity of the disease. The patients had lower mean rCMR(gluc) values than the controls, although differences were not statistically significant. Sum scores of semiquantitative MRI rating scale (Scheltens) correlated significantly with WM CBF but not with rCMR(gluc). CONCLUSIONS: In CADASIL, there is an early and significant decrease in the CBF of WM associated with simultaneous MRI changes. These are obviously caused by the arteriopathy in long penetrating arteries and indicate early tissue damage, also expressed as impaired rCMR(gluc) in the WM.

Adult↗

PubMed2004

Positron emission tomography as an aid in the diagnosis and follow-up of Riedel's thyroiditis.

We describe the usage of positron emission tomography (PET) as an aid in the initial diagnosis and follow-up of Riedel's thyroiditis. A 41-year-old patient was admitted for an enlarged and tender thyroid gland in association with severe systemic symptoms of inflammation. Imaging with fluorine-18 fluorodeoxyglucose (FDG) and PET demonstrated an intensive uptake of FDG in both lobes of the thyroid gland as an indication of severe inflammation. The diagnosis of Riedel's thyroiditis was confirmed by the histological findings of biopsy specimens taken during a palliative thyroid resection. The inflammatory symptoms and local pain dramatically disappeared after commencement of high-dose corticosteroid therapy. A follow-up PET scan after 2 weeks of corticosteroid treatment showed a 60% decrease in the uptake of FDG in the thyroid. This indicates that FDG metabolic activity can also be used to assess a patient's response to therapy in Riedel's thyroiditis.

Journal Article↗

PubMed2004

Effects of subanesthetic ketamine on regional cerebral glucose metabolism in humans.

BACKGROUND: The authors have recently shown with positron emission tomography that subanesthetic doses of racemic ketamine increase cerebral blood flow but do not affect oxygen consumption significantly. In this study, the authors wanted to assess the effects of racemic ketamine on regional glucose metabolic rate (rGMR) in similar conditions to establish whether ketamine truly induces disturbed coupling between cerebral blood flow and metabolism. METHODS: 18F-labeled fluorodeoxyglucose was used as a positron emission tomography tracer to quantify rGMR on 12 brain regions of interest of nine healthy male volunteers at baseline and during a 300-ng/ml ketamine target concentration level. In addition, voxel-based analysis was performed for the relative changes in rGMR using statistical parametric mapping. RESULTS: The mean +/- SD measured ketamine serum concentration was 326.4+/-86.3 ng/ml. The mean arterial pressure was slightly increased (maximally by 16.4%) during ketamine infusion (P < 0.001). Ketamine increased absolute rGMR significantly in most regions of interest studied. The greatest increases were detected in the thalamus (14.6+/-15.9%; P = 0.029) and in the frontal (13.6+/-13.1%; P = 0.011) and parietal cortices (13.1+/-11.2%; P = 0.007). Absolute rGMR was not decreased anywhere in the brain. The voxel-based analysis revealed relative rGMR increases in the frontal, temporal, and parietal cortices. CONCLUSIONS: Global increases in rGMR seem to parallel ketamine-induced increases in cerebral blood flow detected in the authors' earlier study. Therefore, ketamine-induced disturbance of coupling between cerebral blood flow and metabolism is highly unlikely. The previously observed decrease in oxygen extraction fraction may be due to nonoxidative glucose metabolism during ketamine-induced increase in glutamate release.

Adult↗

PubMed2003

A 90-year-old monozygotic female twin pair discordant for Alzheimer's disease.

The present study describes PET, MRI, and neuropsychological findings in 90-year-old monozygotic female twins, who have remained discordant for probable Alzheimer's disease (AD) for at least 7 years. These findings were compared with those of healthy persons composing the reference group (seven women, three men; the mean+/-S.D. age: 73.3+/-3.3 years). Twins' life histories were remarkably similar, except for continuous NSAID use of the unaffected twin for decades. The regional cerebral glucose metabolic rates (rCMRgluc) and all but two CERAD test scores of the affected twin were more than 2 S.D. below the mean values of the reference group. These values were normal in the unaffected twin. The affected twin had moderate hippocampal and temporoparietal atrophy, whereas the hippocampi were intact, and cortical atrophy was mild in the unaffected twin. These findings indicate that the twins were discordant for AD, even though they had reached the age in which the prevalence of AD is high among women. Our results further address the influence of environmental factors on the onset of AD, especially the possible protective effect of anti-inflammatory medication.

Aged↗

PubMed2003

Effects of subanesthetic doses of ketamine on regional cerebral blood flow, oxygen consumption, and blood volume in humans.

BACKGROUND: Animal experiments have demonstrated neuroprotection by ketamine. However, because of its propensity to increase cerebral blood flow, metabolism, and intracranial pressure, its use in neurosurgery or trauma patients has been questioned. METHODS: 15O-labeled water, oxygen, and carbon monoxide were used as positron emission tomography tracers to determine quantitative regional cerebral blood flow (rCBF), metabolic rate of oxygen (rCMRO2), and blood volume (rCBV), respectively, on selected regions of interest of nine healthy male volunteers at baseline and during three escalating concentrations of ketamine (targeted to 30, 100, and 300 ng/ml). In addition, voxel-based analysis for relative changes in rCBF and rCMRO2 was performed using statistical parametric mapping. RESULTS: The mean +/- SD measured ketamine serum concentrations were 37 +/- 8, 132 +/- 19, and 411 +/- 71 ng/ml. Mean arterial pressure was slightly elevated (maximally by 15.3%, P < 0.001) during ketamine infusion. Ketamine increased rCBF in a concentration-dependent manner. In the region-of-interest analysis, the greatest absolute changes were detected at the highest ketamine concentration level in the anterior cingulate (38.2% increase from baseline, P < 0.001), thalamus (28.5%, P < 0.001), putamen (26.8%, P < 0.001), and frontal cortex (25.4%, P < 0.001). Voxel-based analysis revealed marked relative rCBF increases in the anterior cingulate, frontal cortex, and insula. Although absolute rCMRO2 was not changed in the region-of-interest analysis, subtle relative increases in the frontal, parietal, and occipital cortices and decreases predominantly in the cerebellum were detected in the voxel-based analysis. rCBV increased only in the frontal cortex (4%, P = 0.022). CONCLUSIONS: Subanesthetic doses of ketamine induced a global increase in rCBF but no changes in rCMRO2. Consequently, the regional oxygen extraction fraction was decreased. Disturbed coupling of cerebral blood flow and metabolism is, however, considered unlikely because ketamine has been previously shown to increase cerebral glucose metabolism. Only a minor increase in rCBV was detected. Interestingly, the most profound changes in rCBF were observed in structures related to pain processing.

Adult↗

PubMed2003

Regional cerebral glucose metabolism in monozygotic twins discordant for Alzheimer's disease.

We investigated regional cerebral glucose metabolic rates (rCMRgluc) with positron emission tomography using 2-[18F]fluoro-2-deoxy-D-glucose (FDG) in 7 monozygotic twin pairs discordant for Alzheimer's disease (AD). Ten healthy volunteers with comparable mean age and educational level served as controls. In the hippocampus, the mean +/- SD rCMRgluc were 0.20 +/- 0.03 micromol/ml/min for the demented twins, 0.21 +/- 0.03 micromol/ml/min for their non-demented co-twins, and 0.23 +/- 0.02 micromol/ml/min for the controls. The mean hippocampal rCMRgluc was reduced in the demented twins (p = 0.006), compared with the controls. In the lateral temporal cortex, the mean +/- SD rCMRgluc were 0.27 +/- 0.05, 0.28 +/- 0.04, and 0.32 +/- 0.02 micromol/ml/min, respectively. These mean rates were reduced both in the demented (p = 0.02) and the non-demented (p = 0.01) twins, compared with the controls. In conclusion, in the demented twins, the reduction of rCMRgluc was detected in the hippocampus and lateral temporal cortex, i.e. the 2 brain areas which show early changes in pathological and imaging studies in AD. Their non-demented co-twins showed milder reductions, which may be an indication of genetic susceptibility for dementia, and an early sign of a dementing illness in them.

Aged↗

PubMed2002

Personality traits and striatal 6-[18F]fluoro-L-dopa uptake in healthy elderly subjects.

Positron emission tomography (PET) studies have been carried out to examine dopaminergic correlates of human personality traits. In patients with Parkinson's disease, right caudate 6-[(18)F]fluoro-L-dopa ((18)F-dopa) uptake has recently been reported to correlate with a depression/anxiety related-personality trait of harm avoidance. The present study aimed to further study personality and striatal dopaminergic function, now with (18)F-dopa in healthy individuals, and to determine specifically whether the link between harm avoidance and (18)F-dopa uptake is a general phenomenon, seen also in healthy subjects. Twenty-five Caucasian neurologically healthy elderly subjects (mean age=60 years; 13 men, 12 women) were scanned with 3D (18)F-dopa PET, coregistered with magnetic resonance imaging, and each subject filled out the Temperament and Character Inventory (TCI) and the Karolinska Scales of Personality (KSP). The TCI harm avoidance did not correlate with right caudate (18)F-dopa uptake (r=-0.08, P=0.71, uncorrected, effects of age and sex partialled out), or with the (18)F-dopa uptake in any other striatal region (r=-0.07-0.16, P>0.47). Correlations with other personality scales, including the TCI novelty-seeking and the KSP detachment, were also non-significant. The results indicate that the previous positive findings concerning harm avoidance and (18)F-dopa uptake in Parkinson's disease are disease-related, and that they can not be generalized to healthy individuals.

Aged↗

PubMed2002

Age-related loss of extrastriatal dopamine D(2) -like receptors in women.

Positron emission tomography (PET) studies have indicated that the in vivo availability of dopamine D(2) -like receptors declines with age in the human brain. Most of the studies have been carried out with healthy male subjects, or with subject groups containing both sexes. The authors have recently demonstrated that the availability of D(2) -like receptors in the frontal cortex is higher in women than in men. The present study was aimed to further examine this phenomenon. Thirty-seven healthy women (age range 22-78 years) were examined with PET and [(11) C]FLB 457, a high-affinity tracer for the extrastriatal D(2) -like receptors. A negative relationship between age and dopamine D(2) -like receptor availability was seen in the frontal cortex (decrease of 12% per decade of life), the temporal cortex (9%) and the thalamus (6%). A non-linear s-shape association explained the relationship only in the frontal cortex, while in other regions the association was linear. Neither oestradiol nor progesterone levels had a significant relationship with the [(11) C]FLB 457 uptake in any of the brain regions studied after the effect of age was partialled out. The results indicate that: (i) the extrastriatal D(2) -like receptor availability decreases with age in healthy women with the fastest rate in the frontal cortex and with the overall rate close to the rate reported in healthy men; (ii) around midlife (age 40-60 years) in women, the frontal receptor decline plateaus while the decline continues to be linear in other extrastriatal brain regions; and (iii) serum oestradiol or progesterone levels are not associated with cortical or thalamic D(2) -like receptor availability in women. The results may prove to be important in studies where the biochemical basis of clinical sex differences is examined in patients with dopamine-related neuropsychiatric disorders.

Adult↗

PubMed2002

Regional effects of donepezil and rivastigmine on cortical acetylcholinesterase activity in Alzheimer's disease.

Donepezil and rivastigmine are acetylcholinesterase (AChE) inhibitors used to improve cholinergic neurotransmission and cognitive function in Alzheimer's disease (AD). This study examined direct effects of these drugs on AChE activity in the frontal, temporal, and parietal cortices in AD. Six AD patients were scanned with positron emission tomography before and after 3 months of treatment with donepezil (10 mg/day), and five AD patients were scanned before and after 3 to 5 months of treatment with rivastigmine (9 mg/day). Healthy unmedicated controls were imaged twice to evaluate the reproducibility of the method. A specific AChE tracer, [methyl-11C]N-methyl-piperidyl-4-acetate, and a 3D positron emission tomography system with MRI coregistration were used for imaging. Treatment with donepezil reduced the AChE activity (k3 values) in the AD brain by 39% in the frontal (p < 0.001, Bonferroni corrected), 29% in the temporal (p = 0.02, corrected) and 28% in the parietal cortex (p = 0.05, corrected). The corresponding levels of inhibition for rivastigmine were 37% (p = 0.003, corrected), 28% (p = 0.03, uncorrected) and 28% (p = 0.05, corrected). When the treatment groups were combined, the level of AChE inhibition was significantly greater in the frontal cortex compared to the temporal cortex (p = 0.03, corrected). The test-retest analysis with healthy subjects indicated good reproducibility for the method, with a nonsignificant 0% to 7% intrasubject variability between scans. The present study provides first evidence for the effect of rivastigmine on cortical AChE activity. Our results indicate that the pooled effects of donepezil and rivastigmine on brain AChE are greater in the frontal cortex compared to the temporal cortex in AD. This regional difference is probably related to the prominent temporoparietal reduction of AChE in AD. We hypothesize that the clinical improvement in behavioral and attentional symptoms of AD due to AChE inhibitors is associated with the frontal AChE inhibition.

Acetylcholinesterase↗

PubMedDate not supplied

Alexithymia after traumatic brain injury: its relation to magnetic resonance imaging findings and psychiatric disorders.

OBJECTIVE: People with traumatic brain injury (TBI) were studied to assess the prevalence of alexithymia and its relationship to magnetic resonance imaging (MRI) findings and psychiatric disorders. METHODS: Fifty-four participants, 67% men, were evaluated after a median of 30 years since TBI. A control group was matched for age, gender, and severity of depression. Alexithymia was measured with the 20-item Toronto Alexithymia Scale (TAS-20). In patients with TBI, axis I psychiatric disorders were assessed with the Schedules for Clinical Assessment in Neuropsychiatry (SCAN, version 2.1), and axis II disorders with the Structured Clinical Interview for DSM-III-R Personality Disorders (SCID-II). MRI examinations were carried out with a 1.5 T MRI scanner. RESULTS: Alexithymia was significantly more common in patients with TBI than in controls (31.5% versus 14.8%; odds ratio 2.64, 95% confidence interval 1.03-6.80). None of the variables representing TBI, ie, severity of TBI or the presence, laterality, or location of contusions on MRI, was associated with the TAS-20 total scores. Several current axis I and II psychiatric disorders, particularly organic personality syndrome, were connected to higher TAS-20 scores. CONCLUSION: Alexithymia is common, along with psychiatric disorders, in patients with TBI. Both of them may reflect dysfunction of the injured brain. In clinical practice, alexithymic features should be taken into consideration in psychosocial rehabilitation after TBI.

Adult↗