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Biomedical subjects

U Kehler

Publications and source records attributed to U Kehler.

At least 19 recordsLinked to original sources
PubMed2006

Outcome prediction of third ventriculostomy: a proposed hydrocephalus grading system.

An important factor in making a recommendation for different treatment modalities in hydrocephalus patients (VP shunt versus endoscopic third ventriculostomy) is the definition of the underlying pathology which determines the prognosis/outcome of the surgical procedure. Third ventriculostomies (3rd VS) are successful mainly in obstructive hydrocephalus but also in some subtypes of communicating hydrocephalus. A simple, easily applicable grading system that is designed to predict the outcome of 3rd VS is proposed. The hydrocephalus is graded on the basis of the extent of downward bulging of the floor of the third ventricle, which reflects the pressure gradient between the 3rd ventricle and the basal cisterns, presence of directly visualised CSF pathway obstruction in MRI, and the progression of the clinical symptoms resulting in five different grades. In this proposed grading system, grade 1 hydrocephalus subtype shows no downward bulged floor of the 3rd ventricle, no obstruction of the CSF pathway, and no progressive symptoms of hydrocephalus. There is no indication for 3rd VS. Grades 2 to 4 show different combinations of the described parameters. Grade 5 subtype shows a markedly downward bulged floor of the 3rd ventricle and direct detection of the CSF pathway obstruction (i.e., aqueductal stenosis) with progressive clinical deterioration. Retrospective application of this grading scheme to a series of 72 3rd VS has demonstrated a high correlation with the outcome: The success rate in grade 3 reached 40%, in grade 4: 58%, and in grade 5: 95%. This standardised grading system predicts the outcome of 3rd VS and helps in decision making for 3rd VS versus VP shunting.

Adolescent↗
PubMed2005

Surgical treatment of a basilar perforator aneurysm not accessible to endovascular treatment.

Aneurysms originating from perforatoring branches of the midbasilar artery are extremely rare. Rupture of such an aneurysm resulted in a subarachnoid hemorrhage with a prepontine clot in a 44 year old male who presented with an acute confusional state. After coil embolization had failed, the partially thrombosed aneurysm was wrapped and coagulated via a combined supra-/infratentorial subtemporal presigmoid approach in prone position. The postoperative course was complicated by a tension pneumatocephalus and liquorrhea. Additional aneurysms of the anterior communicating artery and right middle cerebral artery were clipped several months later. The patient recovered well, and except for slight gait ataxia no other deficit remained.

Adult↗
PubMed2005

Hollow mandrin facilitates external ventricular drainage placement.

BACKGROUND: Placement of ventricular catheters is a routine procedure in neurosurgery. Ventricle puncture is done using a flexible ventricular catheter stabilised by a solid steel mandrin in order to improve stability during brain penetration. A correct catheter placement is confirmed after removing the solid steel mandrin by observation of cerebrospinal fluid (CSF) flow out of the flexible catheter. Incorrect placement makes further punctures necessary. The newly developed device allows CSF flow observation during the puncture procedure and in addition precise intracranial pressure (ICP) measurement. METHOD: The developed mandrin is hollow with a blunt tip. On one side 4-5 small holes with a diameter of 0.8 mm are drilled corresponding exactly with the holes in the ventricular catheter, allowing CSF to pass into the hollow mandrin as soon as the ventricle is reached. By connecting a small translucent tube at the distal portion of the hollow mandrin ICP can be measured without loss of CSF. The system has been used in 15 patients with subarachnoid haemorrhage (SAH) or intraventricular haemeorrhage (IVH) and subsequent hydrocephalus. FINDINGS: The new system improved the external ventricular drainage implantation procedure. In all 15 patients catheter placement was correct. ICP measurement was easy to perform immediately at ventricle puncture. In 4 patients at puncture no spontaneous CSF flow was observed, therefore by connecting a syringe and gentle aspiration of CSF correct placement was confirmed in this unexpected low pressure hydrocephalus. Otherwise by using the conventional technique further punctures would have been necessary. CONCLUSIONS: Advantages of the new technique are less puncture procedures with a lower risk of damage to neural structures and reduced risk of intracranial haemorrhages. Implantation of the ventricular catheter to far into the brain can be monitored and this complication can be overcome. Using the connected pressure monitoring tube an exact measurement of the opening intracranial pressure can be obtained performed without losing CSF.

Catheters, Indwelling↗
PubMed2003

Cerebral haemodynamic pathologies in HELLP syndrome.

The syndrome of haemolysis, elevated liver enzymes and low platelets (HELLP syndrome) is understood as a unique variant of severe preeclampsia. This disorder complicates between 2 and 7% of gestations and is associated with a high perinatal morbidity and a maternal morbidity ranging between 1 and 4%. Intracerebral complications only rarely occur, especially intracerebral haemorrhage was described only in single cases, often correlated with fatal maternal outcome. The analysis of patients with HELLP syndrome treated at our hospital revealed three cases with severe neurological deterioration. Possible pathogenetic factors are discussed.

Adult↗
PubMed2003

The mechanism of fornix lesions in 3rd ventriculostomy.

Fornix lesions as a complication of 3rd ventriculostomy are rare and almost not reported. However, in our series of 94 procedures we observed 5 fornix lesions. Although we did not find any clinical deterioration, we were alarmed by these unexpected incidences and analysed the mechanism. All fornix lesions occurred using an endoscope sheath with separated channels for the endoscope itself, the instruments and for rinsing and suction. The limited field of view suggests the surgeon to be already inside the 3rd ventricle while the tip of the scope is still in the lateral ventricle just before the foramen of Monro. The instrument enters the optic field--depending on the used optic--as lately as 2 to 3 mm. The analysis showed that the lesions happened when the instruments were in the blind angle of the endoscope's optic which itself was outside of the foramen of Monro. Being aware of this mechanism with its potential risks it did not occurred again.

Endoscopy↗
PubMed2003

Pro and cons of different designs of rigid endoscopes.

Experience with more than 200 neuroendoscopic procedures taught us the advantages and disadvantages of the different endoscope designs. Using an endoscope with a sheath with separate channels for the endoscope, the instruments as well as for rinsing and suction we found advantages in rinsing properties, handling, and preciseness of instrument steering. On the other hand an endoscope with a sheath with a singular channel for the endoscope itself, the instruments, rinsing, and suction the advantages were better in visualization of the instruments, more available instruments, and easier extraction of larger specimen. The knowledge of these advantages makes it possible to select the adequate endoscope regarding its design, especially in more complicated cases.

Brain Diseases↗
PubMed2003

Extraventricular intracisternal obstructive hydrocephalus--a hypothesis to explain successful 3rd ventriculostomy in communicating hydrocephalus.

The basis of successful 3rd ventriculostomy in cases of communicating hydrocephalus is not yet understood. We performed 3rd ventriculostomies in 5 patients with free cerebrospinal fluid (CSF) communication from the ventricles to the cisterna magna. Preoperative magnetic resonance images (MRIs) showed dilated ventricles, a downward bulging floor of the 3rd ventricle (interpreted as a sign of pressure gradient between the ventricles and basal cisterns) and a free communication to an enlarged cisterna magna. The other basal cisterns were of normal or smaller size. All patients recovered from their clinical symptoms and none of them needed a shunt. The hypothesis of an intracisternal CSF pathway obstruction (e.g. between the cisterna magna and the prepontine cistern) could explain the MRI findings, although such an obstruction cannot be directly visualized. It would also explain the successful 3rd ventriculostomies in these cases.

Child, Preschool↗
PubMed2002

An in vitro study to evaluate the accuracy of stereotactic localization using magnetic resonance imaging by means of the Leksell stereotactic system.

The advantages of using magnetic resonance imaging (MRI) as opposed to computed tomographic (CT) scans or ventriculography in stereotactic surgery include the increased tissue contrast of the lesion or target, direct non-reformatted multiplanar imaging and target coordinate determination as well as reduced imaging artefacts produced by the stereotactic frame. One disadvantage of MR stereotaxis, however, is the potential for anatomic inaccuracy due to equipment-induced inhomogeneities of the magnetic field. The authors present an experimental study on an in vitro model to examine the accuracy of target localization using the Leksell stereotactic frame and MR imaging. Ten formalin-fixed brains taken from patients who had died of non-neurological diseases were sealed in a properly modelled plaster-cast shell simulating the skull bone. These models were fixed in the Leksell stereotactic frame and high-field MR images were performed (Siemens Magnetom SP 1.5 Tesla, T1-weighted spin echo sequences, TR/TE 600/15 ms, slice thickness 2 mm, FOV 300 mm). Following electrocoagulation of different targets on both lentiforme nuclei, the localization and extension of the lesions were controlled by MRI. A gross-/histopathological verification was performed. This model allows a good representation of the anatomic structures without any artefacts. The postoperative MRI control and the pathological examination of the lesions matched well with the preoperatively defined targets. The correlation of coordinates and measurements obtained with the pathological studies were within a +/- 2 mm range in all cases.

Brain↗
PubMed2001

Twenty colloid cysts--comparison of endoscopic and microsurgical management.

The management of colloid cyst remains controversial, evaluation of the competing methods seems to be necessary. We report on our experience with colloid cysts in the last decade: ten were managed solely endoscopically, 10 were resected microsurgically (9 via a transcortical/transventricular, 1 via a transcallosal approach). The outcome in the endoscopic group was excellent in 9 cases and unsatisfying in 1 case (recurrence). In the microsurgical group we achieved a good outcome in 5 of 10 cases, a fair outcome in 4 cases and 1 lethal outcome (caused by pulmonary embolism). Complications in the endoscopic group: one intraoperative bleeding, 1 stitch granuloma, 1 mispuncture of the ventricle, and 1 meningitis. Complications in the microsurgical group: 1 subdural effusion, 1 flap infection, 1 mild hemiparesis, 1 transient impairment of consciousness and 1 pulmonary embolism. Mean operative time and length of hospitalization of the endoscopic group were clearly shorter than in the microsurgical group: 91 min versus 267 min time of surgery, 5.1 days versus 18.9 days of hospitalization. Complete resection was achieved in 8 of 10 cases of microsurgery, and in 3 of 10 cases in endoscopy. Endoscopic management results in lower costs and superior patients' comfort. The reduced number of total resections in the endoscopic group may lead to a higher recurrence rate in long-term follow-up, which might be a serious disadvantage of endoscopy. However, more experience in the endoscopic techniques may result in a higher rate of total resection of colloid cysts.

Adult↗
PubMed2000

HELLP syndrome with haemaglobin vasospasm.

The syndrome of haemolysis, elevated liver enzymes and low platelets (HELLP syndrome) is a life threatening, severe complication of pre-eclampsia with typical laboratory findings. An unusual case of a 36-year-old woman with HELLP syndrome and the initial complication of intracerebral haemorrhage is presented. The diagnosis of HELLP syndrome was confirmed by elevated liver enzymes, low platelets, increased total bilirubin and increased lactate dehydrogenase. The intracranial haematoma was removed with good neurological recovery ensuing. However, this case was complicated by cerebral vasospasm on the eleventh day, confirmed by cerebral angiography and computer tomographic findings. The patient died from brain swelling. Possible vasospam should be considered during the treatment of patients with HELLP syndrome.

Adult↗
PubMed2000

[Endoscopic use of the water jet dissector in the cerebral ventricle system--an experimental study].

Endoscopic surgery in the cerebral ventricle is limited by the small number of suitable instruments and bleedings obscuring the visibility. The water jet cutter allows the dissection of tissue, generally leaving vessels intact. Therefore it could be an additional instrument for neuroendoscopic purposes. In this preclinical study the employment of the water jet dissector under endoscopic conditions was evaluated. Incision-experiments (n = 80) on the ventricular system of fresh porcine brain were carried out under endoscopic view. To achieve similarity to the ventricular system, specimens were dissected in liquid medium (Ringer's-lactate, 37 degrees C). The depths of incision were measured digitally and histological examination of the tissue was performed. Depending on the applied pressure, distance from cutting nozzle to tissue and cutting velocity, the depths of incision ranged from 0.12 mm up to 2.4 mm. The water jet dissector is good to handle under endoscopic conditions and vessels are preserved. Based on these factors, this instrument is predestinated for further neuroendoscopic application. Prior to clinical application our results will have to be tested on living, perfused cerebral tissue.

Animals↗
PubMed1999

Pituitary apoplexy after cardiac surgery presenting as deep coma with dilated pupils.

Acute clinical deterioration due to infarction or haemorrhage of an existing, often previously unrecognized, pituitary tumour is a rare but well-described complication. It can occur spontaneously or may be caused e.g. by mechanical ventilation, infection or surgical procedures. We report on a case of pituitary apoplexy occurring in a 64-year-old patient 3 weeks after cardiac surgery. The patient presented with deep coma and dilated pupils. Magnetic resonance imaging revealed a haemorrhagic pituitary tumour. After prompt endocrinologic replacement therapy with levothyroxine and hydrocortisone the patient regained consciousness. Neurological examination revealed right oculomotor nerve palsy and bilateral cranial nerve VI palsy. Subsequent trans-sphenoidal removal of a nonfunctional macroadenoma with large necrotic areas was performed. The patient recovered completely. To our knowledge, pituitary tumours presenting with a combination of deep coma and dilated pupils must be considered exceedingly rare. Possible pathophysiologic mechanisms are discussed. As our case illustrates, even in severe cases complete recovery is possible if the diagnosis is suspected, and diagnostic and therapeutic measures are initiated in time.

Coma↗
PubMed1999

A new technique for attaching a stereotactic frame to the head: technical note.

The aim of this study was to develop a device which allows an intermediate, painless fixation of a stereotactic frame prior to definite pin fixation. To stabilize the stereotactic frame rubber coated metal springs were used. By testing the springs on 30 volunteers with different head diameters and circumferences the optimal shape was determined. In the clinical setting 15 patients undergoing stereotactic surgery were tested, stability and patient's convenience were measured. The procedure was well tolerated and measurements revealed symmetric distances between head and frame. Therefore these metal springs are a useful accessory to the Leksell stereotactic system.

External Fixators↗
PubMed1998

Intracerebral hematomas caused by aneurysm rupture. Experience with 67 cases.

During a six-year (1986-1992) 334 patients with subarachnoid hemorrhage (SAH) were admitted to the Department of Neurosurgery. Medical University of Lübeck, Germany. In 281 patients the SAH was caused by rupture of an intracranial arterial aneurysm, verified by angiography, postmortem examination, or at emergency operation without angiography. In 67 (23.8%) of the 281 aneurysmal SAH patients the initial computerized tomography (CT) demonstrated an intracerebral hematoma (ICH). An ICH localized in the temporal lobe due to the rupture of a middle cerebral artery (MCA) aneurysm was found in 47 patients (70.2%). Forty-three patients were considered for surgery with a surgical mortality of 8 (18.6%). In the group of 19 ICH patients not operated upon, 16 individuals died (84.2%). We therefore advocate active surgical management of ICH patients: hematoma evacuation and aneurysm clipping at the same operation. Emergency surgery in younger patients (grade V) with temporal ICH suggesting the rupture of a MCA or internal carotid artery (ICA) aneurysm can be done without angiography.

Adult↗
PubMed1998

Spontaneous recovery of an aqueductal stenosis.

The case of a 17-year-old male with hydrocephalus caused by aqueductal obstruction is presented. A ventriculo-peritoneal shunt was implanted and later removed due to an infection. In the clinical follow-up no deterioration was observed. No further surgery was necessary. The repeat-MRI showed spontaneous resolution of the hydrocephalus with a normal aqueduct.

Adolescent↗