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Biomedical subjects

A Danek

Publications and source records attributed to A Danek.

At least 19 recordsLinked to original sources
PubMed1996

Deactivation of human visual cortex during involuntary ocular oscillations. A PET activation study.

Prompted by the observation of decreased glucose metabolism in the striate and extrastriate visual cortex in a patient with opsoclonus, we studied the influence of involuntary eye movements on visual cortex activity. Repeated measurements of cerebral blood flow (CBF) by PET were performed in 12 healthy volunteers using H2(15)O-bolus technique after ear canal irrigation with ice cold or warm (44 degrees C) water with the subjects eyes closed. In addition to blood flow increases in areas involved in central vestibular processing, statistical subtraction analysis revealed a nearly symmetrical, bilateral, highly significant decrease in the occipital cortex covering Brodmann areas 17, 18, and 19 after ice water stimulation of either ears. Region of interest analysis revealed in all subjects a mean decrease in regional CBF (rCBF) of 12.8% (range 4.6-21.0%) in these areas. A similar but less pronounced effect (mean rCBF decrease in visual cortex 4.8%, range 1.1-11.5%) was observed after warm water irrigation. The observations suggest that deactivation of the visual cortex is induced by involuntary ocular oscillations. This deactivation is not dependent on changes of the retinal input (eyes closed). The physiological significance of this hitherto unknown phenomenon may be the protection from inadequate visual input (oscillopsia) during involuntary ocular oscillations.

Adult↗
PubMed1996

Lyme neuroborreliosis disguised as normal pressure hydrocephalus.

A 74-year-old woman presented with gait impairment, urinary incontinence, and dementia. She showed lymphocytic CSF pleocytosis and pronounced intrathecal Borrelia burgdorferi antibody production, indicating active Lyme neuroborreliosis. The syndrome of normal-pressure hydrocephalus (NPH) fully remitted after ceftriaxone treatment. Lyme neuroborreliosis may cause NPH by interfering with subarachnoid CSF flow.

Aged↗
PubMed1995

[Lacunar cerebral infarction in a young woman].

HISTORY AND FINDINGS: A 29-year-old woman was admitted to hospital with an acute right-sided hemiplegia and sensory disorders, as well as upper right quadrant anopsia. There were no other significant abnormalities. She had previously been healthy and was free of any predisposing risk factors for thromboembolism. Neurological examination elicited a homonymous right upper quadrant hemianopsia, dysesthesia of the right half of the face and hypesthesia and hypalgesia of the right side of the body. In addition there was paresis of the right arm and a positive right Babinski reflex. INVESTIGATIONS: There was no evidence for any underlying haematological, metabolic, infectious or vascular disease. Computed tomography of the head revealed a small hypodense area immediately adjacent to the posterior part of the left internal capsule, compatible with a lacunar infarction, a finding confirmed by magnetic resonance imaging and relating to the area supplied by the thalamic branch of the posterior cerebral artery. Transoesophageal echocardiography demonstrated a patent foramen ovale. TREATMENT AND COURSE: Almost complete regression of all signs occurred within two months on anticoagulation with heparin intravenously for two weeks followed by oral phenprocoumon (Quick's value 30-40%) and intensive physiotherapy. Five weeks after onset of treatment the paresis was obviously regressing and pyramidal tract signs had disappeared. Sensitivity to touch over the right half of the body was still diminished and the homonymous paracentral scotoma still present. CONCLUSION: Lacunar infarction of the brain in young patients has an excellent prognosis, as long as it is treated intensively according to its cause.

Acute Disease↗
PubMed1995

Persistent mirror movements: force and timing of "mirroring" are task-dependent.

A simple isometric motor task was used to quantify intended and unintended finger movements in two subjects (father and son) with persistent mirror movements. One hand voluntarily changed grip force between thumb and index finger at different amplitudes and frequencies, while the other hand was to maintain a constant force. During all experimental conditions the "steady" hand showed insuppressible, highly cross-correlated contractions, compatible with bilateral distribution of a single motor command to the spinal cord. However, these associated movements were not strictly mirror images, nor did they show a fixed relationship to the voluntary movements across experimental conditions. The ratio of mirror to voluntary movement ranged from 1.4 to 19.1% and from 3.4 to 78.4% in the two subjects and was directly related to voluntary strength and speed. At maximum speed, mirror activity tended to precede voluntary activity, while it was delayed in slow force changes. Comparable time lags were not found in control subjects instructed to simulate mirror movements. We conclude that neuronal mechanisms in addition to bilateral corticomotoneuronal connections are at work in persistent mirror movements.

Adult↗
PubMed1995

Movement-related cortical potentials in persistent mirror movements.

Mirror movements (MMs) are involuntary movements executed on one side of the body during voluntary movements of the contralateral homologous body parts which may abnormally persist into adulthood. In 6 subjects affected by persistent MM with autosomal dominant inheritance, movement-related cortical potentials (MRCPs) during self-paced, voluntary extensions of either the left or right middle finger were recorded from 30 EEG electrodes simultaneously with the electromyogram (EMG) of both extensor digitorum communis muscles. The negative potentials before and during EMG onset were evaluated statistically for the two electrodes next to the cortical hand areas. A comparison with 7 normal subjects revealed no marked differences for the Bereitschaftspotential (BP) and the negative slope (NS'). Only in the periods around EMG onset (from -50 to +50 msec) a significant difference between both groups was found. The MM subjects showed fairly symmetric potentials over the right and left hemispheres, whereas the potentials of the control subjects were lateralized to the hemisphere contralateral to the intended movement. No difference was found for the amplitude of the maximum negative peak of MRCP following EMG onset. Our data showed no evidence for a different type of movement preparation in MM subjects as compared to normals. We propose that the additional ipsilateral cortical activation around movement onset may be the cortical mechanism, which compensates for abnormal ipsilateral corticospinal pathways in subjects with persistent MM.

Adolescent↗
PubMed1995

[Functional magnetic resonance tomography of the visual cortex].

Functional magnetic resonance imaging (MRI) allows to directly visualize regional activity of the visual cortex during stimulation. The value of the method to evaluate physiologic and pathologic conditions is elaborated on in comparison with positron emission tomography (PET). Aspects as sequence selection and stimulus paradigms are discussed. Subtle activity in the primary cortex (V1), processing areas as MT/V5 and subcortical areas are visualized by MRI. Cooperation of the subjects is a essential factor. Despite promising initial results in clinical trials the focus of research in clinical trials the focus of research in the visual cortex yet remains in the preclinical field.

Animals↗
PubMed1994

Isolation of the gene for McLeod syndrome that encodes a novel membrane transport protein.

McLeod syndrome is an X-linked multisystem disorder characterized by abnormalities in the neuromuscular and hematopoietic systems. We have assembled a cosmid contig of 360 kb that encompasses the McLeod gene locus. A 50 kb deletion was detected by screening DNA from patients with radiolabeled whole cosmids, and two transcription units were identified within this deletion. The mRNA expression pattern of one of them, designated as XK, correlates closely to the McLeod phenotype. XK encodes a novel protein with structural characteristics of prokaryotic and eukaryotic membrane transport proteins. Nucleotide sequence analysis of XK from two unrelated McLeod patients has identified point mutations at conserved splice donor and acceptor sites. These findings provide direct evidence that XK is responsible for McLeod syndrome.

Amino Acid Sequence↗
PubMed1994

Vestibular cortex lesions affect the perception of verticality.

Seventy-one patients with unilateral supratentorial infarctions were evaluated with respect to static vestibular function in the roll plane, including determinations of the subjective visual vertical, skew deviation, and ocular torsion. Since animal studies have revealed at least four different areas of the parietal and temporal cortex involved in vestibular function, we tried to identify cortical areas in humans responsible for vestibular function in the roll plane. Infarcted areas, as demonstrated in magnetic resonance and computed tomography scans, were projected onto the appropriate sections of an atlas of the human brain. Infarctions in the territories of the posterior and anterior cerebral arteries did not affect static vestibular function in roll. Twenty-three of 52 patients with infarctions in the middle cerebral artery territory showed significant (p < 0.0005), mostly contraversive, pathological subjective visual vertical tilts. The overlapping area of these infarctions centered on the posterior insula, probably homologous to the parieto-insular vestibular cortex in the monkey. Although electrophysiological and cytoarchitectonic data in animals demonstrate several multisensory areas rather than a single primary vestibular cortex, the parieto-insular vestibular cortex seems to represent the integration center of the multisensory vestibular cortex areas within the parietal lobe.

Adolescent↗
PubMed1994

Decrease in androgen binding and effect of androgen treatment in a case of X-linked bulbospinal neuronopathy.

X-linked recessive bulbospinal neuronopathy is a motoneuron disorder to be distinguished from amyotrophic lateral sclerosis, Effective treatment is not known. Patients with X-linked recessive bulbospinal neuronopathy may show gynecomastia and testicular atrophy, and a mutation in the androgen receptor gene has been found associated with the disease. Intermediate steps leading from the androgen receptor abnormality to the clinical syndrome have not yet been elucidated. Therefore, binding of androgen ([3H]dihydrotestosterone) to its specific receptor by genital skin fibroblasts cultured from a patient with X-linked recessive bulbospinal neuronopathy and confirmed androgen receptor mutation was studied. Markedly decreased binding capacity was found. We treated the patient for 6 months with nandrolone-decanoate. No effect on his neuromuscular status was observed during 2 years of follow-up.

Anabolic Agents↗
PubMed1994

Olfactory function in patients with hypogonadotropic hypogonadism: an all-or-none phenomenon?

Hypogonadotropic hypogonadism (HH) refers to an endocrine defect of hypothalamic origin resulting in gonadal hypoplasia and frequently associated with anosmia or severely impaired olfactory function (Kallmann's syndrome). This apparently results from a disruption in the migration of neurons from the olfactory placode to the bulb and hypothalamus early in development, and so provides a unique opportunity to investigate olfactory function in human subjects with congenitally incomplete peripheral systems. Olfactory performance in 37 HH patients and 37 age-matched controls was compared using a modified version of the Munich Olfaction Test. This test is based on the sniff-bottle method and includes tests of (i) odor quality discrimination, (ii) intensity discrimination, (iii) detection thresholds, and (iv) recognition, hedonic evaluation and identification ability. The patients could be divided into two distinct groups differing significantly on all four subtests and showing no overlap in performance: 20 anosmics, conforming to Kallmann's syndrome, and 17 apparent normosmics whose performance was slightly poorer, but not significantly different to that of the controls. The unexpected failure to find a continuum of olfactory dysfunction now raises the question whether HH with or without anosmia represents two syndromes with distinct etiologies, or rather reflects the ability of the olfactory system to function well despite morphological impairment.

Adult↗
PubMed1994

Kallman syndrome versus idiopathic hypogonadotropic hypogonadism at MR imaging.

PURPOSE: To identify morphologic differences between Kallman syndrome (KS) and idiopathic hypogonadotropic hypogonadism (IHH) and establish a role for magnetic resonance (MR) imaging in these disorders. MATERIALS AND METHODS: Twenty-eight patients were compared with 10 eugonal male volunteers. Eighteen patients had KS (hypogonadotropic hypogonadism with anosmia) and 10 had IHH. All participants underwent hormone analysis, a sniff-bottle smell test, and gadolinium-enhanced MR imaging. Changes in the hypothalamic-hypophyseal region and the rhinencephalon were evaluated. RESULTS: MR imaging revealed intracranial morphologic changes in all patients on plain T1-weighted sections. Seventeen patients with KS demonstrated aplasia of an olfactory bulb; one olfactory sulcus was absent in six, rudimentary in four, and normal in eight. Olfactory bulbs were present in all 10 IHH patients and three showed one slightly hypoplastic bulb. Ten patients with KS and three with IHH showed an enlarged paranasal sinus system. Further MR findings were similar. CONCLUSION: MR imaging demonstrates abnormalities of the rhinencephalon present in KS patients and occasionally absent in IHH patients.

Adult↗
PubMed1994

Cerebral involvement in McLeod syndrome.

McLeod syndrome is an Xp21-linked Kell blood group variant due to lack of erythrocyte protein Kx with associated RBC membrane dysfunction such as acanthocytosis. A man with this syndrome developed chorea and slight neuropsychological impairment. He had caudate atrophy on cerebral imaging and reduced striatal dopamine D2-receptor binding on single-photon emission computed tomography. Since Xp21 was partly deleted in the patient, the missing gene product (possibly Kx) may be essential for the integrity of the striatum.

Benzamides↗
PubMed1993

[McLeod syndrome].

Explore the source record for details and available documents.

Blood Proteins↗
PubMed1993

Geniospasm: hereditary chin trembling.

Geniospasm is a hereditary disorder characterized by episodic, usually stress-induced involuntary trembling of the chin. Nineteen families from Europe and the U.S.A. suffering from this disorder have been described since 1894. We present three cases from two newly detected families. There was no evidence of any other nervous system abnormality, although abnormal EEG, sleep disorders, and involvement of other facial muscles have been described in rare cases. Geniospasm is transmitted as an autosomal-dominant trait with high penetrance. It must be differentiated from facial myokymia, palatal tremor, and essential tremor affecting facial muscles. Neurophysiological and molecular mechanisms of this peculiar disorder are unknown.

Adolescent↗
PubMed1993

Motor recovery following capsular stroke. Role of descending pathways from multiple motor areas.

The functional anatomy of motor recovery was studied by assessing motor function quantitatively in 23 patients following capsular or striatocapsular stroke. While selective basal ganglia lesions (caudate and/or putamen exclusively) did not affect voluntary movements of the extremities, lesions of the anterior (plus caudate/putamen) or posterior limb of the internal capsule led to an initially severe motor impairment followed by excellent recovery, hand function included. In contrast, lesions of the posterior limb of the internal capsule in combination with damage to lateral thalamus compromised motor outcome. In experimental tracing of the topography of the internal capsule in macaque monkeys, we found axons of primary motor cortex passing through the middle third of the posterior limb of the internal capsule. Axons of premotor cortex (dorsolateral and post-arcuate area 6) passed through the capsular genu, and those of supplementary motor area (mesial area 6) through the anterior limb. Small capsular lesion can therefore disrupt the output of functionally and anatomically distinct motor areas selectively. The clinically similar motor deficits with a similar course of functional restitution following disruption of these different descending motor pathways indicate a parallel operation of cortical motor areas. They may have the further capability of substituting each other functionally in the process of recovery from hemiparesis.

Adult↗
PubMed1992

Cortically evoked motor responses in patients with Xp22.3-linked Kallmann's syndrome and in female gene carriers.

Patients with Kallmann's syndrome show hypothalamic hypogonadism, hyposmia, and congenital mirror movements. As a correlate, a defect of gonadotropic neuron migration into the brain was recently detected. Considering abnormal outgrowth of neurons also as a possible substrate underlying mirror movements, we studied 3 patients and 2 asymptomatic female gene carriers from a kindred with proven linkage to Xp22.3, using focal transcranial magnetic stimulation of motor cortex hand areas with a figure-eight coil. In all 3 affected brothers, bilateral responses could be evoked almost simultaneously in their thenar muscles (slight latency differences were statistically insignificant). In contrast, the mother and the maternal aunt showed only unilateral, normal thenar responses, even with maximum tolerable stimulator output and high signal amplification. Correspondingly, mirror movements were present in the patients, but not in the gene carriers. Bilaterality of cortically evoked hand muscle responses and mirror movements, therefore, behaved as X-chromosomal recessive traits. A likely cause might be a disorder of neuronal outgrowth in the motor system, particularly of inhibitory callosal fibers. For normal anatomical development of the motor system, one intact Xp22.3 gene seems necessary.

Agenesis of Corpus Callosum↗
PubMed1992

McLeod syndrome: a distinct form of neuroacanthocytosis. Report of two cases and literature review with emphasis on neuromuscular manifestations.

McLeod syndrome was originally described on the basis of a specific blood group phenotype with weak expression of Kell antigens. This erythrocyte abnormality also causes acanthocytosis. The haematological findings are associated with abnormalities in other organ systems, including neuromuscular manifestations. A 51-year-old patient was followed up for 11 years. He presented with persistent muscle creatine kinase elevation and progressive heart disease and later developed a slowly progressive neuropathy and choreic movements. His younger brother presented with grand mal seizures, involuntary movements and high muscle creatine kinase when aged 43 years. Clinical myopathy was absent in both, yet muscle biopsy showed mild myopathic changes. The presence of a motor axonopathy was supported by electrophysiological findings. One brother also showed sensory axonopathy. The movement disorder suggested accompanying basal ganglia dysfunction. Earlier reports of McLeod syndrome are reviewed with respect to neuromuscular involvement. Absence of the Kx membrane protein seems to be the cause of this multi-system disorder.

Acanthocytes↗