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Biomedical subjects

L Ketonen

Publications and source records attributed to L Ketonen.

At least 19 recordsLinked to original sources
PubMed1996

Cognitive performance and regional brain volume in human immunodeficiency virus type 1 infection.

BACKGROUND: Brain atrophy has been reported to occur in advancing human immunodeficiency virus (HIV) infection, particularly in patients with HIV-related dementia. Atrophy of the caudate region, as assessed by magnetic resonance imaging measures, has been reported to correlate with cognitive impairment in patients with HIV infection; however, differences in the severity of HIV-induced immunosuppression may have contributed to these findings. OBJECTIVE: To determine the relationship between regional brain volumes and cognitive performance in individuals with HIV infection. PATIENTS AND METHODS: We evaluated 11 patients with advanced HIV disease by using neuropsychologic tests and quantitative magnetic resonance imaging volume analysis. SETTING: University hospital, involving patients from a clinical trial. RESULTS: Caudate volume, expressed as a ratio of total intracranial volume, correlated with performance on the Trails A and Grooved Pegboard tests, but not with other tests of memory, motor speed, or mood (adjusted for age and education). Hippocampal volume did not correlate with any of the neuropsychologic tests. CONCLUSIONS: Caudate volume in patients with advanced HIV disease is associated with poor performance on neuropsychologic tests of complex motor and sequencing skills. Hippocampal volume does not appear to be related to impairment on neuropsychologic tests. These findings are independent of the degree of immunosuppression and the overall extent of brain atrophy; however, these results must be interpreted with some caution, given the limited sample size.

Adult↗
PubMed1996

Laminar cortical necrosis in MELAS syndrome: MR and neuropathological observations.

Laminar cortical necrosis has been described in many conditions of cellular energy depletion, such as hypoxia and hypoglycemia. In MELAS, a genetic defect in mitochondrial protein synthesis leads to impairment of oxidative phosphorylation, with subsequent insufficient energy production within the cell. Neurons are more vulnerable to energy depletion than glial cells and vascular elements, and among the layers of the cerebral cortex the lower laminae are more vulnerable than the superficial layers. We studied a child with severe MELAS syndrome two months before death with MR and compared the images to autopsy findings, including macroscopic specimens and light and electron microscopy. The MR images showed an excellent correlation with the neuropathological results and displayed the various degrees of damage to the brain tissue caused by deficient energy production. Acute laminar cortical necrosis was seen as swelling of the cortex with intracortical hyperintense bands in T2-weighted images. The subacute stage with focal cortical hemorrhage was displayed as hyperintensity of the gyral surface in T1-weighted and hypointensity in T2-weighted images, with T2-hyperintensity and swelling of the rest of the cortex and underlying white matter. Severe cortical atrophy represented the chronic stage.

Atrophy↗
PubMed1995

Segmentation and feature extraction techniques, with applications to MRI head studies.

To obtain a three-dimensional reconstruction of the hippocampus from a volumetric MRI head study, it is necessary to separate that structure not only from the surrounding white matter, but also from contiguous areas of gray matter--the amygdala and cerebral cortex. At present it is necessary for a physician to manually segment the hippocampus on each slice of the volume to obtain such a reconstruction. This process is time consuming, and is subject to inter- and intraoperator variation as well as large discontinuities between slices. We propose a novel technique, making use of a combination of gray scale and edge-detection algorithms and some a priori knowledge, by which a computer may make an unsupervised identification of a given structure through a series of contiguous images. This technique is applicable even if the structure includes so-called false contours or missing contours. Applications include three-dimensional reconstruction of difficult-to-segment regions of the brain, and volumetric measurements of structures from series of two-dimensional images.

Algorithms↗
PubMed1994

Acute cerebellar hemorrhage secondary to capillary telangiectasia in an infant. A case report.

We encountered an unusual case of an acute cerebellar hemorrhage secondary to a capillary telangiectasia in a 4-month-old infant. Prompt surgical evacuation of the cerebellar hematoma resulted in an excellent neurologic outcome. To the best of our knowledge, ours represents the only clinical case report of massive cerebellar bleed due to a capillary telangiectasia.

Acute Disease↗
PubMed1994

Band heterotopia.

Explore the source record for details and available documents.

Brain Neoplasms↗
PubMed1993

Opportunistic cerebral vasculopathy and stroke in patients with the acquired immunodeficiency syndrome.

OBJECTIVE: To describe an unusual cause of stroke in patients with the acquired immunodeficiency syndrome. DESIGN: An observational case series of hospitalized patients with subsequent autopsy. MEASURES: Clinical, radiological, and pathological examinations were performed. RESULTS: In three of 14 patients with stroke, the infarctions were secondary to an opportunistic vasculopathy caused by Candida albicans, cytomegalovirus, or lymphoma. CONCLUSION: Opportunistic conditions may lead to vascular abnormalities and subsequent stroke in patients with the acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Cerebrospinal fluid and MRI findings in three patients with multiple sclerosis and systemic lupus erythematosus.

Three patients fulfilling the diagnostic criteria of both multiple sclerosis (MS) and systemic lupus erythematosus (SLE) were examined clinically, immunologically and by magnetic resonance imaging (MRI). In all three patients MRI showed several high-signal lesions compatible with MS and, additionally, non-specific small white matter lesions suggesting small vessel occlusion were seen. In CSF the cytoimmunological abnormalities were variable and showed only slight to moderate immunoactivation within the CNS at the time of sampling.

Adult↗
PubMed1993

Effects of recombinant alpha-2b-interferon therapy in patients with progressive MS.

The effects of systemic recombinant interferon-alpha-2b were studied in 6 carefully selected patients with progressive multiple sclerosis. 3.0 million IU were given as daily subcutaneous injections for 6 months, 5 patients showed worsening disability, and in 4 of them new or enlarged lesions were detected in MRI. In one patient no change in disability was found; his MRI showed regressed changes. The mean progression index during the treatment was significantly higher (p < 0.02) than during the previous 2 to 3 years' period of continuous progression. The frequency of peripheral blood natural killer (CD16+) cells declined significantly 3 months during the treatment, but returned to the pretreatment values after termination the treatment. An increase of intrathecal IgG synthesis and oligoclonal bands was demonstrated in 4 and 3 patients, respectively. Our experience suggests that long-term recombinant IFN-alpha-2b treatment may activate the immunological process of MS.

Adult↗
PubMed1993

Co-twin control study on cerebral manifestations of systemic lupus erythematosus.

All available twin pairs systemic lupus erythematosus (SLE) derived from the Finnish Twin Cohort were studied by clinical evaluation, magnetic resonance imaging (MRI), anticardiolipin (aCL), and antineurofilament (ANFA) antibodies. One of the five monozygotic and one of the eight dizygotic pairs were concordant for SLE. 10 of the 15 patients showed clinical neurological abnormalities, and 11 had abnormal MRI of the brain. Altogether, 12 patients were considered to have neuropsychiatric lupus (NPSLE). Seven of the 11 patients with long-term corticosteroid treatment had either central or cortical atrophy. High or moderate aCL level was found in eight patients and two co-twins. Of them, six patients had at least two manifestations of the antiphospholipid syndrome. ANFAs were found in five patients and four co-twins. Five co-twins fulfilled some of the SLE criteria. Of them, three MZ twins and one additional DZ co-twin with no ARA criteria had findings suggesting central nervous system (CNS) involvement. The results indicate that the majority of SLE patients has cerebral abnormalities either as a result of SLE, or concomitant risk factors. The co-twins without clinical SLE often have minor signs of SLE, and even they may have neurological and MRI abnormalities. However, their aCL and ANFA levels seem not to correlate with MRI abnormalities.

Adolescent↗
PubMed1993

Neoplastic meningitis as the presentation of occult primitive neuroectodermal tumors.

Seven children and young adults initially presented with subacute meningitis and/or increased intracranial pressure. The diagnosis of neoplastic meningitis secondary to a primitive neuroectodermal neoplasm was delayed by the absence of an obvious primary tumor. The neuroradiologic appearance was that of a basimeningeal infiltrative process, complicated by communicating hydrocephalus or "pseudotumor cerebri." Myelography was important in the diagnosis of disseminated meningeal malignancy in four cases. Cerebrospinal fluid cytologic diagnosis was insensitive but ultimately confirmed in five cases. All seven patients experienced progressive disease despite neuraxis radiotherapy and intensive chemotherapy; six have died. Systemic dissemination to bone and/or peritoneum occurred in three patients while on therapy. In two, a primary parenchymal brain or spinal cord tumor could not be identified at postmortem examination. The presentation of a primitive neuroectodermal tumor as subacute meningitis without an evident primary tumor heralds an aggressive and refractory neoplasm.

Adolescent↗
PubMed1991

Osseous and muscular changes after vertical ramus osteotomy. A magnetic resonance imaging study.

Magnetic resonance (MR) imaging was performed about 2 years after vertical ramus osteotomy of 10 patients to study changes in the mandibular condyle, cortical and cancellous bone of the proximal fragment, and muscles of mastication. MR imaging observations of the surgically treated patients were compared with findings in 10 asymptomatic untreated control subjects. The results showed that the MR appearance of bone marrow of the mandibular condyle was normal in all patients and in all control subjects. No MR evidence of avascular necrosis of the mandibular condyle was found. MR imaging artifacts from microscopic metallic particles were seen in all surgically treated regions. Thickening of the buccal and lingual cortical bone with narrowing of the bone marrow space was seen bilaterally in eight patients and unilaterally in two patients. Slight medial tipping of the mandibular condyle was seen unilaterally in two patients. Atrophic changes with decreased muscle volume and fatty replacement of muscle tissue was seen unilaterally in eight patients. None of these alterations were seen in the control subjects. MR imaging appears to be an excellent method to study morphologic changes of the muscles of mastication and osseous fragments after orthognathic surgery of the mandible. Thickening of the cortical bone and narrowing of the bone marrow space of the proximal fragment was frequently seen after vertical ramus osteotomy of the mandible and most likely represents remodeling associated with normal healing.

Adolescent↗
PubMed1991

Manic syndrome in AIDS.

A manic syndrome in eight patients with AIDS is described. On the basis of clinical, neuropsychological, laboratory, magnetic resonance imaging, and epidemiological evidence, the authors suggest that the manic syndrome was secondary to HIV infection. The patients also developed concomitant cognitive impairment.

AIDS Dementia Complex↗
PubMed1990

Magnetic resonance imaging findings in HIV cognitive impairment.

Atrophy and white matter changes seen on magnetic resonance imaging scans have been observed in association with the acquired immunodeficiency syndrome dementia complex, but these appear to be late findings relative to clinical expression. We report a new magnetic resonance imaging observation in patients with early cognitive impairment due to human immunodeficiency virus infection. Fifty-two patients had a total of 86 magnetic resonance imaging scans during the study period. All scans were obtained with a 1.5-T system. The proton density spin echo (repetition time of 2000 milliseconds and echo delay time of 30 milliseconds) study demonstrated high-signal lesions in the region of the splenium of the corpus callosum and in the crura of the fornices. The lesions demonstrated no contrast enhancement with gadopentate dimeglumine. Pathological examination was performed in five patients. The fornix-subcallosal abnormality may be related to the memory dysfunction in patients with human immunodeficiency virus-related cognitive impairment.

Adult↗
PubMed1990

MS and SLE in twins of successive generations.

During a nationwide twin study on multiple sclerosis (MS) in Finland a dizygotic pair discordant for MS was found. The affected co-twin had dizygotic twin daughters. The affected co-twin of the second generation had systemic lupus erythematosus (SLE). Both pairs were thoroughly examined. No evidence of CNS involvement in the healthy co-twins was found. In pairwise comparisons, virus-specific IgG antibodies to measles and mumps were significantly increased in the MS patient whereas the same was true for rubella in the SLE patient. Both MS and SLE patient expressed HLA alleles most often found to be associated with these disorders. Reversed CD4/CD8 ratios were observed in both MS and SLE patient. No difference in interleukin-2 receptor expression were found but gamma-interferon secretion in the MS patient showed marked increase whereas that of the SLE patient was of the same magnitude as in the healthy members. A different triggering stimulus rather than the dissimilarity in the immunogenetic predisposition may be decisive as to whether or not they develop MS or SLE.

Adult↗