PubMed Health⌕ Search

Biomedical subjects

K Alfke

Publications and source records attributed to K Alfke.

6 recordsLinked to original sources
PubMed2006

Voxel-based morphometry shows no decreases in cerebellar gray matter volume in essential tremor.

OBJECTIVE: To investigate cerebellar gray matter volume in patients with essential tremor (ET). METHODS: We used voxel-based morphometry (VBM) based on high-resolution T1-weighted MRI to compare gray and white matter density between 27 patients with ET and 27 age- and sex-matched healthy control subjects. Fourteen patients had only postural tremor, whereas 13 patients showed additional intention tremor. RESULTS: VBM failed to demonstrate regional decreases in gray and white matter volume in patients with ET. There was, however, an expansion in gray matter depending on the type of tremor. Compared with age-matched control groups, patients with intention tremor showed a relative expansion of gray matter bilaterally in the region of the temporoparietal junction and the right middle occipital cortex. CONCLUSIONS: The lack of a consistent decrease in gray and white matter density argues against a progressive neurodegenerative process in essential tremor that leads to a substantial decrease in cerebellar gray matter volume. Patients with predominant intention tremor show a relative expansion of gray matter areas involved in higher order visuospatial processing, which might represent a long-term result of adaptive reorganization compensating the higher demands on the visuospatial control of skilled movements in case of trembling.

Adult↗
PubMed2006

Selective affection of hippocampal CA-1 neurons in patients with transient global amnesia without long-term sequelae.

The aetiology, pathomechanisms and anatomical correlates of transient global amnesia (TGA) still remain obscure. Recently, focal MR-signal diffusion-weighted imaging (DWI) changes in the hippocampus have been described in patients with TGA, but the exact localization, long term outcome and pathophysiological nature of these lesions still remain unknown. The topography and time course of hippocampal DWI lesions in 41 TGA patients was studied using serial 3 T high-resolution MR-imaging and correlated to clinical and neuropsychometric results. Of these, 29 patients showed 36 DWI lesions with corresponding T(2) lesions in the hippocampus within a time window of 48 h after onset. Almost all lesions (94%; 34/36) were selectively found in the CA-1 sector (Sommer sector) of the hippocampal cornu ammonis. Most DWI lesions (8/10) were already detectable in the peri-acute phase <6 h after onset of symptoms. A follow-up study 4-6 months after the episode did not show evidence for residual structural sequelae of these lesions (n = 20/20). A venous MR angiography of the intracranial dural sinus showed an asymmetric venous drainage in 21/24 (88%) patients. In 11/16 (69%) patients with unilateral lesions, the asymmetry corresponded to the side of the DWI lesion. Significant episodic verbal memory deficits in the acute phase (n = 14/18) were associated with lesions of the dominant hemisphere while impairment of visuospatial memory was associated with lesions of the non-dominant hemisphere. Persistent neuropsychological sequelae were not detected 4-6 months after the episode (n = 16). This is the first prospective study combining high-resolution imaging and neuropsychometry analysing the detailed functional anatomy and outcome of hippocampal DWI/T(2) lesions in TGA supporting the view the TGA being a benign transient disorder. The TGA can be considered a model for a focal transient perturbation of memory circuits in the temporo-mesial region.

Adult↗
PubMed2006

[Endovascular therapy of stroke].

Standard therapy of acute ischaemic stroke during the first three hours after symptom onset is intravenous thrombolysis. When contraindications exist, an endovascular approach might be possible. Intraarterial administration of thrombolytic drugs is the most common way. Additionally, there is an increasing use of mechanical tools that are expected to be faster and more effective. Three principles of mechanical thrombolysis are known: aspiration, extraction and fracturing of the thrombus. Different tools were tested clinically and some demonstrated its high efficiency. Larger studies are needed to compare those tools. Apart from recanalization of a cerebral vessel occlusion implantation of a stent might be necessary for prophylaxis of recurrent stroke.

Anticoagulants↗
PubMed2005

[MRI of carotid stents: influence of stent properties and sequence parameters on visualization of the carotid artery lumen].

PURPOSE: To evaluate MR artifacts of carotid artery stents and to optimize stent properties and sequence parameters. MATERIAL AND METHODS: Four carotid artery stents - Wallstent (mediloy), Precise (nitinol), ACCULINK (nitinol) and a stent prototype (nitinol) - were investigated in a flow model of the cervical vessels. The model was made of silicon tubing and a flow pump that produces realistic flow curves of the carotid artery. To investigate the effects of magnetic susceptibility and radiofrequency induced shielding artifacts, turbo spin echo and gradient echo sequences as well as CE-MRAs were measured. To improve the visualization of the stent lumen in a CE-MRA, flip angle as well as geometry and covering of the stent prototype were altered. RESULTS: Susceptibility artifacts in stents of the carotid artery only influence the lumen visualization at the proximal and distal end of the braided mediloy stent. A change of stent coverings has no significant influence on radiofrequency artifacts, whereas a reduction in linking elements between stent segments and a change in diameter of stent struts improves visualization of the stent lumen. By increasing the flip angle in a CE-MRA, visualization of the stent lumen is possible in both mediloy and nitinol stents. CONCLUSION: The choice of stent material and changes in stent geometry as well as the optimization of the flip angle of the CE-MRA may reduce susceptibility and radiofrequency artifacts, rendering feasible the CE-MRA of a stented carotid artery.

Alloys↗
PubMed1998

[Meningeal irritation--a complication of herpes zoster].

HISTORY AND CLINICAL FINDINGS: A previously healthy 26-year-old man complained of gradually increasing headache after an attack of flu. After 4 days an erythema with papules but no blisters was noted in the area of distribution of the left 10th thoracic nerve. As a child he had varicella (chickenpox) without complications. INVESTIGATIONS: Lymphocytic pleocytosis and evidence of an abnormal blood-brain barrier were noted in cerebrospinal fluid (CSF). Serology for varicella zoster virus revealed an IgG titre of > 7400 IU/l in serum and 21 IU/l in CSF. The corresponding IgM titres were negative. TREATMENT AND COURSE: The headaches and cutaneous changes regressed under i.v. treatment with acyclovir, 10 mg/kg body weight, 3 x daily for 10 days. Repeat CSF examination after 10 days showed merely minimal residual changes of inflammation. CONCLUSION: This case illustrates the risk of severe neurological complications of herpes zoster infection. A seemingly minor rash with headache must be correctly diagnosed and immediate high-dosage acyclovir treatment instituted to prevent life-threatening and severe complications of herpes zoster meningitis or encephalitis.

Acyclovir↗