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Biomedical subjects

W Küker

Publications and source records attributed to W Küker.

At least 55 records · Page 3Linked to original sources
PubMed2001

The role of intraoperative magnetic resonance imaging for the detection of hemorrhagic complications during surgery for intracerebral lesions an experimental approach.

BACKGROUND: Intraoperative magnetic resonance imaging (MRI) for guided biopsy or microsurgical resection of intracranial lesions is gaining broader acceptance. It is not known whether intraoperative MRI has the potential to detect hemorrhagic complications of these surgical procedures, because scientific research has so far focussed on the signal characteristics of less acute clots. It is the objective of this experimental study to investigate whether MRI can visualise intracerebral blood within minutes after its occurrence. METHODS: In 26 pigs, a frontal hematoma was produced by injecting autologous blood. Twenty pigs underwent MRI 30 minutes after injection, and 6 pigs within the first 10 minutes. MRI scans were performed on a 1.5T system. T1-weighted spin echo (SE), T2-weighted turbo spin echo (TSE), T2-weighted fluid attenuated inversion recovery (FLAIR), and T2-weighted gradient echo (GE) images were acquired. Depending on the differences of the signal intensities of the hematoma and the surrounding brain, the detectability of the hematoma was rated as good, fair, or poor. RESULTS: None of the induced hematomas were rated to be clearly visible on T1-weighted sequences. Six of the 26 hematomas (23%) were easily detectable on FLAIR sequences, 18 hematomas (69%) on T2-weighted TSE sequences, and 23 hematomas (88%) on the T2-weighted GE sequences. CONCLUSION: Extravasated blood can be identified with a high reliability within minutes after its occurrence on MRI provided that T2-weighted GE sequences are used for imaging. In conclusion, intraoperative MRI is not only of value for guidance of neurosurgical procedures, but also for immediate detection of hemorrhagic complications.

Animals↗
PubMed2001

Proton MR spectroscopy reveals lactate in infantile neuroaxonal dystrophy (INAD).

Changes of cerebral metabolites detected by proton MR spectroscopy in two cases of infantile neuroaxonal dystrophy are described. A 6 11/12-year-old boy and a girl (aged 4 1/12 years at the first and 5 2/12 years at the second examination) with infantile neuroaxonal dystrophy were investigated by magnetic resonance imaging and spectroscopy of the basal ganglia. The signal intensity of the cerebellar cortex was increased on T2-weighted, proton density, and fluid attenuated inversion recovery images. The long echo time (135 ms) spectra revealed the presence of lactate in the basal ganglia of both cases in all investigations. The N-acetylaspartate/creatine ratio was reduced in Case 1 and in the second investigation of Case 2. The choline/creatine ratio was always increased. As the diagnosis of infantile neuroaxonal dystrophy is made by a synopsis of various clinical, neuropathological, neurophysiological, and neuroradiological data, the presence of lactate in the basal ganglia spectra may help to narrow down the diagnosis and can support the decision to perform more invasive diagnostic procedures (such as biopsies of skin, conjunctiva or even of the brain).

Aspartic Acid↗
PubMed2001

[Contrast enhanced MR-angiography (CE-MRA): do contrast media with higher T1 relaxation improve imaging of carotid stenoses?].

PURPOSE: CE-MRA is a powerful tool for the non-invasive evaluation of carotid artery occlusive disease. However, due to certain drawbacks, it has not completely replaced DSA. The purpose of this study was to evaluate if Gd-BOPTA, a contrast agent with high T1 relaxivity, can increase the diagnostic accuracy of CE-MRA. MATERIAL AND METHODS: The CE-MRA examinations of 54 consecutive patients were evaluated by two experienced radiologists, independently. The examinations of 27 patients were contrasted either with 20 ml Gd-BOPTA or with 20 ml Gd-DTPA. The reviewers were blinded to the contrast agent chosen and to the ultrasound results. They rated the overall image quality and the degree of the ICA stenoses. RESULTS: For the estimation of the degree of the ICA stenoses there was a high interrater validity. In comparison to the ultrasound findings, 6 of 50 high-degree stenoses were underestimated as moderate stenoses. In one of seven sonographically occluded vessels, MRA revealed residual patency in the vessel lumen. It was not possible to identify the contrast agent that was taken for a study. Subjective estimation of the image quality (arterial contrast of the ICA, contrast of the other vessels, and general impression) did not significantly change with the contrast agent employed. CONCLUSION: The diagnostic accuracy of CE-MRA for the evaluation of internal carotid artery stenoses is not improved by Gd-BOPTA if identical volumina of contrast media are applied. The potential of this contrast agent can be the reduction of the amount of contrast without loss of diagnostic information. Further studies are necessary.

Aged↗
PubMed2001

Unilateral thalamic edema in internal cerebral venous thrombosis: is it mostly left?

Thrombotic occlusion of the internal cerebral veins is a particularly dangerous form of cerebral venous thrombosis (CVT) as it causes venous infarction of the thalami. Because both thalami drain into the vein of Galen and straight sinus, bilateral thalamic involvement is frequently encountered in internal CVT. However, unilateral thalamic edema may also occur, even if all internal cerebral veins are occluded. This suggests collateral venous drainage of the thalami, which is commonly insufficient in internal CVT. Patients with unilateral congestion of the thalamus, including 3 patients reported here, had mostly left-sided involvement, indicating that right-sided unilateral thalamic involvement in CVT may be clinically silent.

Adult↗
PubMed2001

Spontaneous occlusion of a cerebral arteriovenous malformation: angiography and MR imaging follow-up and review of the literature.

We present the angiographic and MR imaging course of a 62-year-old man with a right parietal high-flow arteriovenous malformation (AVM), which was diagnosed because of seizures. A spontaneous, complete, and asymptomatic occlusion of the AVM was confirmed by a second angiography 3 months later. The possible mechanisms leading to the occlusion are discussed, and a brief review of the literature is given.

Angiography, Digital Subtraction↗
PubMed2000

Is the head position during preoperative image data acquisition essential for the accuracy of navigated brain tumor surgery?

OBJECTIVE: To analyze the influence of head positioning during preoperative image data acquisition on intraoperative accuracy of modern neuronavigation systems. MATERIAL AND METHODS: All measurements were performed preoperatively before opening the head. In 24 patients, preoperative MR image data acquisition was performed twice on a 0.5 T scanner using a contrast-enhanced T1-weighted sequence; first in the neutral head position, and thereafter in the surgical head position for pterional craniotomy. For both data sets, the Sylvian fissure, the central sulcus, and the superior and inferior temporal sulci were depicted on the patient's scalp using the frameless neuronavigation system EasyGuide Neurotrade mark. At the beginning of surgery, with the head fixed in a Mayfield clamp and an articulated instrument holder being used for fixation of the navigation system's pointer, the distances of 10 correlating points of the sulci for the two data sets were measured. To evaluate the accuracy of the navigation system in this experimental set-up, a phantom study was also performed. RESULTS: The phantom study revealed a mean inaccuracy of 1.6 mm (range 0.1-2.3 mm, standard deviation 0.6 mm). The patient study revealed a mean inaccuracy of 1.8 mm (range 0.4-2.8 mm, standard deviation 0.5 mm). CONCLUSIONS: The data suggest that the positioning of the patient's head during preoperative imaging plays no relevant role in intraoperative accuracy of neuronavigation. However, further studies and a larger number of patients with various pathologies in different regions of the brain are necessary to obtain a better understanding of the problem of brain shift in neuronavigation due to patient positioning alone, and to avoid procedure-related operative morbidity.

Adult↗
PubMed2000

[Raeder- and Collet-Siccard-Syndrome. Acute pareses of cranial nerves symptomatic of a dissection of internal carotid artery].

Acute cerebral nerve paresis can be caused in many different ways. One of the more rare causes of paresis of one or more neural pathways is dissection of the internal carotid artery. Early diagnosis is important, even with atypical symptoms, since prompt anticoagulative therapy can hinder stroke from embolism due to the dissection. We report on two patients with Raeder's syndrome and Collet-Sicard syndrome resulting from dissection of the internal carotid artery. Besides the cranial and caudal nerves involved in our study, loss of function has also been reported with the sixth to eighth cranial nerves, so that any painful, sudden cranial nerve deficiency can indicate possible carotid dissection.

Acute Disease↗
PubMed2000

Classification of acquired lesions of the corpus callosum with MRI.

MRI has facilitated diagnostic assessment of the corpus callosum. Diagnostic classification of solitary or multiple lesions of the corpus callosum has not attracted much attention, although signal abnormalities are not uncommon. Our aim was to identify characteristic imaging features of lesions frequently encountered in practice. We reviewed the case histories of 59 patients with lesions shown on MRI. The nature of the lesions was based on clinical features and/or long term follow-up (ischaemic 20, Virchow-Robin spaces 3, diffuse axonal injury 7, multiple sclerosis 11, hydrocephalus 5, acute disseminated encephalomyelitis 5, Marchiafava-Bignami disease 4, lymphoma 2, glioblastoma hamartoma each 1). The location in the sagittal plane, the relationship to the borders of the corpus callosum and midline and the size were documented. The 20 ischaemic lesions were asymmetrical but adjacent to the midline; the latter was involved in new or large lesions. Diffuse axonal injury commonly resulted in large lesions, which tended to be asymmetrical; the midline and borders of the corpus callosum were always involved. Lesions in MS were small, at the lower border of the corpus callosum next to the septum pellucidum, and crossed the midline asymmetrically. Acute disseminated encephalomyelitis and the other perivenous inflammatory diseases caused relatively large, asymmetrical lesions. Hydrocephalus resulted in lesions of the upper part of the corpus callosum, and mostly in its posterior two thirds; they were found in the midline. Lesions in Marchiafava-Bignami disease were large, often symmetrically in the midline in the splenium and did not reach the edge of the corpus callosum.

Adolescent↗
PubMed2000

Presumed capillary telangiectasia of the pons: MRI and follow-up.

Capillary telangiectasia is a vascular abnormality primarily of the brainstem. The clinical relevance is unclear as is the association with clearly pathologic findings such as cavernous haemangioma. We report on four cases with capillary telangiectasia proven by follow-up and describe the imaging characteristics. T2 abnormality was only observed in half of the patients as was the presence of a discernable collecting vein. Whereas two cases were incidental findings in neurologically normal persons and one had symptoms clearly attributable to lacunar stroke, one patient may have had symptoms due to the vascular abnormality in the pons.

Adult↗
PubMed2000

Virtual pointer projection of the central sulcus to the outside of the skull using frameless neuronavigation -- accuracy and applications.

BACKGROUND: The purpose of this prospective study was to localize the central sulcus by frameless neuronavigation and to project this anatomical structure to the outside of the skull on the skin. This method was analyzed in respect to its practicability, accuracy, and potential applications. METHOD: In 27 patients investigated (28 unaffected hemispheres), the central sulcus was virtually projected to the outside of the skull using frameless neuronavigation and a virtual pointer elongation of 15 or 20 mm. The following parameters were measured on the scalp: 1. the distance between the bregma and the midline junction of the central sulcus, and 2. the angle between the central sulcus and the midline. These dada were compared with measurements based on the original axial MR images of these patients. Finally, a laboratory phantom study was designed in analogy to a patient's examination for estimation of the overall accuracy of the neuronavigation system in the experimental setup used in this study. FINDINGS: Virtual pointer projection of the central sulcus to the outside of the skull using frameless neuronavigation was found to be easily possible. The distance between the bregma and the midline junction of the central sulcus amounted to a mean of 55 mm on the left and 56 mm on the right. The angle between the central sulcus and the midline reached a mean of 63 degrees on the left and 60 degrees on the right. These data confirmed results of other studies with no frameless neuronavigation devices. The phantom study revealed a mean overall inaccuracy of 0.9 mm at a virtual pointer elongation of 15 mm. At a virtual pointer elongation of 20 mm, the mean overall inaccuracy of our study was 1.1 mm. These results correspond to the inaccuracy of frame based stereotaxy. INTERPRETATION: It is easily possible, valid, and reliable to virtually project the central sulcus to the outside of the skull with an acceptably low inaccuracy using frameless neuronavigation. This is important for research studies that correlate and integrate different functional imaging methods with the aid of frameless neuronavigation.

Adult↗
PubMed2000

Spinal subdural and epidural haematomas: diagnostic and therapeutic aspects in acute and subacute cases.

BACKGROUND: The diagnosis of spontaneous spinal haematomas mainly depends on magnetic resonance imaging. This study evaluates the MRI characteristics of spinal epidural and subdural haematomas. The results were correlated with medical history, coagulation abnormalities and therapeutic outcome to provide guidelines for early diagnosis and treatment of spinal epidural and subdural hematomas. SUMMARY OF BACKGROUND DATA: Imaging signs of epidural and subdural haematomas have been reported before, however without special attention to the differential-diagnostic and therapeutic implications of haematoma localisation. METHOD: Seven patients (3 women, 4 men, age range 55-86 years) with acute progressive neurological deficits and without a history of severe trauma were studied. In all cases neurological examinations were performed after admission followed by MRI studies with T2 and T1 weighted images, before and after administration of contrast agent. Spinal angiography was performed twice to exclude a vascular malformation. All patients underwent open surgery. FINDINGS: Acute and subacute hematomas were detected once in the cervical spine, in five cases in the thoracic region and once in the lumbar region. The hematomas had an epidural location in three cases and a subdural in four. In the thoracic region subdural haemorrhage was much more common than epidural hematomas. Subdural blood collections were mainly found ventral to the spinal cord. Epidural haemorrhage was always located dorsal to the spinal cord. The evaluation of the haematoma localisation may be difficult occasionally, but delineation of the dura is frequently possible in good quality MRI. The clue to the diagnosis of ventrally located subdural haemorrhage is the absence of the "curtain sign", which is typical for epidural tumours. INTERPRETATION: Spontaneous spinal hematomas are frequently located in the thoracic spine. Subdural spinal haemorrhage is more frequent than epidural. Epidural haemorrhage is frequently located dorsal to the spinal cord because of the tight fixation of the dura to the vertebral bodies.

Aged↗
PubMed2000

Microsurgical treatment of spontaneous and non-spontaneous spinal epidural haematomas: neurological outcome in relation to aetiology.

BACKGROUND: This retrospective study evaluated the neurological outcome of 26 patients with spontaneous and non-spontaneous spinal epidural haematoma (SEH) who underwent microsurgical clot removal. It was the objective of the present study to investigate whether the aetiology of the SEH has an influence on the neurological outcome. METHODS: The medical records and radiological investigations of 26 patients with SEH were re-examined, and the latency between symptom onset and operation, and the size of the haematoma were determined. Motor and sensory function had been evaluated before surgery and 90 days after discharge. FINDINGS: Fourteen patients with non-spontaneous SEH and 12 patients with spontaneous SEH were identified. After surgery, neurological deficits improved in 9 of the patients with spontaneous (75%) and in 13 of the patients with non-spontaneous SEH (93%). In cases of spontaneous SEH, the median latency between symptom onset and operation was longer (72 hrs vs 7 hrs) and the median extent of the haematoma was larger (3.5 vs 2 spinal segments), than in the non-spontaneous cases. INTERPRETATION: Neurological outcome seems to be related to the aetiology of the SEH. Better outcome was observed in patients with surgically treated non-spontaneous SEH. Two explanations for this finding are worth considering. First, patients with non-spontaneous SEH usually are already under medical surveillance and can undergo medullary decompression more rapidly. Second, the compression of the spinal cord is possibly less severe in non-spontaneous SEH because of their smaller size.

Adolescent↗
PubMed2000

Congenital bilateral perisylvian syndrome (CBPS): do concomitant esophageal malformations indicate a poor prognosis?

Congenital bilateral perisylvian syndrome (CBPS) is a syndrome of cortical malformation characterized by faciopharyngoglossomasticatory diplegia. We report on two cases of CBPS with associated esophageal malformations and a poor mental and motor development. The association of CBPS and esophageal malformations may indicate a subgroup of patients with a very early prenatal injury, characterised by a bad prognosis due to severe cortical disorganization. However, it can not be excluded that the association of CBPS and esophageal malformation is purely coincidental.

Abnormalities, Multiple↗
PubMed2000

Experimental acute intracerebral hemorrhage. Value of MR sequences for a safe diagnosis at 1.5 and 0.5 T.

PURPOSE: To determine the detectability of intracerebral hematomas with MR imaging at 1.5 T and 0.5 T with fluid attenuated inversion recovery turbo spinecho (FLAIR) and gradient-echo sequences. MATERIAL AND METHODS: Twenty-seven intracerebral hematomas were created in 25 piglets by injection of venous blood into the brain through a burr hole. All were imaged with T2*-weighted gradient echo sequences (fast field echo, FFE), T2-weighted fluid attenuated inversion recovery turbo spin-echo sequences (FLAIR), T2-weighted turbo spin-echo (TSE) and T1-weighted spinecho sequences. Follow-up was performed on the 2nd, 4th and 10th postoperative days. Ten animals were additionally investigated with similar sequences at 0.5 T. Histologic correlation was obtained in all cases. RESULTS: T2* FFE sequences detected all acute intracerebral hematomas and demonstrated the size correctly at 1.5 T and 0.5 T. The conspicuity was better at 1.5 T. FLAIR sequences were unreliable in the hyperacute phase at 1.5 T: However. subarachnoid and intraventricular extension was best appreciated with FLAIR images. T2 TSE images were incapable of detecting paraventricular and subarachnoid hemorrhages, but clearly demonstrated intracerebral blood in other locations. TI-weighted images were insensitive to hemorrhage in the acute state but very useful in subacute and chronic hematomas. CONCLUSION: The safe and reliable diagnosis of intracerebral hemorrhage is probably possible with MR imaging at 1.5 T and 0.5 T even of hematomas less than 90 min old, but requires the application of at least FLAIR, T2* FFE and T1 sequences and is therefore time consuming.

Acute Disease↗
PubMed2000

Prospective analysis of bedside percutaneous subdural tapping for the treatment of chronic subdural haematoma in adults.

OBJECTIVES: Although there is general agreement that surgery is the best treatment for chronic subdural haematoma (CSDH), the extent of the surgical intervention is not well defined. METHODS: The less invasive surgical technique of bedside percutaneous subdural tapping and spontaneous haematoma efflux after twist drill craniostomy under local anaesthesia was prospectively analysed in 118 adult patients, 99 with unilateral and 19 with bilateral CSDH. RESULTS: The mean number of subdural tappings was 3.2. Ninety two of the patients with unilateral CSDH were successfully treated by up to five subdural tappings, 95% of the patients with bilateral CSDH were successfully treated by up to 10 subdural tappings. The mean duration of inpatient treatment was 12 days. In 11 patients (9%) the treatment protocol had to be abandoned because of two acute subdural bleedings, two subdural empyemas, and seven cases of insufficient haematoma efflux and no neurological improvement. The only significant predictor for failure of the described treatment protocol was septation visible on preoperative CT. CONCLUSIONS: The described therapy protocol is-apart from a purely conservative treatment-the least invasive presently available surgical technique for treating chronic subdural haematoma. Its results are comparable with other modern treatment protocols. Thus, it can be recommended in all patients as a first and minimally invasive therapy, especially in patients in a poor general condition. Patients with septation visible on preoperative CT should be excluded from this form of treatment.

Adult↗