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Biomedical subjects

H G Imhof

Publications and source records attributed to H G Imhof.

At least 19 recordsLinked to original sources
PubMed2005

Distal posterior inferior cerebellar artery aneurysms: clinical characteristics and surgical management.

BACKGROUND: Aneurysms located on the distal posterior inferior cerebellar artery (PICA) are rare, and their underlying clinical features and surgical management are poorly understood. We report our series of 16 patients with 18 distal PICA aneurysms. METHOD: All patients with distal PICA aneurysms were treated between March 1996 and August 2004. We excluded all PICA aneurysms that involved the vertebral artery. Patients were analysed in the light of their clinical profiles, radiological studies, intraoperative findings and outcomes. All patients underwent non-enhanced and contrast enhanced CT scans followed by 4-vessel cerebral angiography on admission. The hemorrhagic patterns on initial CT scans were assessed using the Fisher Grading Score. The outcomes were documented using the Glasgow Outcome Scale at time of discharge and at three or twelve months follow-up. FINDINGS: The series included 6 men and 10 women. Massive intraventricular haemorrhage was found in 13 patients with proven CT subarachnoid haemorrhage, one patient revealed SAH without intraventricular components, one presented with only intraventricular blood in the occipital horns and 3 aneurysms were found incidentally without presence of blood. Fourteen aneurysms were saccular and four were fusiform. Nine cases were associated with another cerebrovascular lesion. A lateral transcondylar or a median suboccipital approach was used to secure the aneurysms in 15 patients, either by direct clipping (14 lesions) or vessel sacrifice (3 lesions). One aneurysm was treated by an endovascular approach. At long-term follow up, an excellent or good outcome was achieved in 75% of cases. One patient died due to pre-existing cardiopulmonary complications. CONCLUSIONS: Most of our cases of ruptured distal PICA aneurysms presented with haematocephalus. These were frequently associated with another vascular abnormality and 22% were fusiform or multilobulated. These specific features require special management strategies entailing an appropriate surgical approach to the aneurysm, clipping method, haematoma removal, ventricular drainage and when suitable choice of endovascular interventions.

Adult↗
PubMed2005

Management of ruptured aneurysms combined with coexisting aneurysms.

In patients suffering from subarachnoid haemorrhage (SAH) and presenting with multiple intracranial aneurysms (MIA) two questions have to be decided on: 1st when is the ideal moment to eliminate the ruptured aneurysm and 2nd when to treat the coexisting aneurysms. In our series we retrospectively analysed 124 SAH-patients presenting with a total of 323 aneurysms. In 57 patients the ruptured aneurysm and all coexisting aneurysms were clipped during the first operation, whereas in 9 patients only some of the coexisting aneurysms (group-A; age in median 55 years) were clipped besides the ruptured one. In 55 patients (group-B; age in median 55 years) the first operation was restricted to clipping the ruptured aneurysm, dealing with the coexisting aneurysm subsequently. Immediately after admission 3 patients passed away. One of the 64 patients waiting (average 60 days, median 14 days) for the subsequent clipping of the not yet secured aneurysms suffered a SAH. Six to 12 months after the initial SAH, 78% of the cases in both groups reached a Glasgow Outcome Score of 4 or 5. Even if in patients with coexisting unruptured intracranial aneurysms the elimination of each and every aneurysm is recommended, the advantages of an unstaged procedure versus the additional strain caused by the prolongation of the procedure, e.g. approach over the midline, 2 or more craniotomies, and the risk of additional ischemic damage to the brain, caused by increased manipulation of cerebral arteries and brain tissue, have to be carefully considered. This is of special importance in dealing with patients in higher Hunt and Hess grades.

Adult↗
PubMed2005

Three cases of AVM at eloquent areas finally treated with conventional microsurgical method.

Three special cases of AVM finally treated with conventional microsurgical method are presented. Two cases of medium sized AVMs were located at the central region, one of them was primarily treated with Gamma-knife followed by endovascular embolization having been complicated with growing cyst formation followed ultimately by microsurgical removal. The AVM of another case was embolized three times, followed by removal of the residual nidus under awake surgery. The third AVM located at the hypothalamus in the vicinity of the optic nerve was considered unsuitable for embolization and Gamma-knife therapy, and therefore removed by microsurgery using special approaches after a trial of embolization. In terms of microsurgical removal, preoperative embolization, embolization material, awake surgery and selection of special approaches are discussed.

Adult↗
PubMed2005

Conventional microsurgical treatment of paraclinoid aneurysms: state of the art with the use of the selective extradural anterior clinoidectomy SEAC.

Surgical treatment of paraclinoid aneurysms is considered to be difficult due to their complicated anatomical location in the vicinity of important neural, vascular and bony structures. We present our clinical experience of the past 10 years of conventional microsurgical treatment of 81 paraclinoid aneurysms in 75 patients with the use of selective extradural anterior clinoidectomy SEAC and discuss the method of therapy option by reviewing recent reports on results of endovascular coiling method and the combination of these with conventional microsurgical therapy. The favorable surgical results with the use of SEAC and no recurrence of the treated aneurysm after clipping procedure in our series indicate that direct surgery can still be a standard technique for paraclinoid aneurysms in view of the fact that the endovascular aneurysm coiling methods are still associated with a considerable percentage of incomplete occlusion and present the problem of coil packing.

Blood Vessel Prosthesis↗
PubMed2005

Basilar bifurcation aneurysms. Lessons learnt from 40 consecutive cases.

Basilar bifurcation aneurysms are lately treated frequently with endovascular technique. Microsurgical clipping occlusion technique has, however, still its solid position because of its completeness. This standard technique is required often due to unfeasibility and/or incompleteness at the time of application of the endovascular technique for aneurysms of this location. The authors suggest following strategies and tactics for safe and secure occlusion of aneurysms of this location: pterional approach, selective extradural anterior clinoidectomy SEAC, no transection of the posterior communicating artery, isolation of perforating arteries at the time of neck clipping with oxycellulose and combination of the use of fenestrated clip and conventional clip (especially for aneurysms projected posteriorly), controlled hypotension (systolic pressure of around 100 mmHg), temporary clipping (trapping) procedures of usually less than 15 min. All these are aimed for prevention of intraoperative premature rupture, and of injury of perforating arteries and for complete occlusion of aneurysms in the narrow depth of the operative field.

Adult↗
PubMed2003

Moyamoya disease and Moyamoya syndrome: experience in Europe; choice of revascularisation procedures.

OBJECTIVES: To present our clinical experience in terms of disease presentation and choice of revascularisation procedure in our first group of 23 European Moyamoya angiopathy (disease and syndrome) patients. METHOD AND PATIENT SELECTION: Twenty three patients were diagnosed and treated from 1997-2001 in our neurosurgical department. All patients underwent preoperative angiography, colour Doppler examination, cranial MRI and/or CT scans, HMPAO-SPECT or H(2)(15)O PET (baseline and Diamox challenge) scans. Nineteen patients presented with child-juvenile Moyamoya angiopathy with an average age at presentation of 8 years (range 1-17 years), in 4 patients adult Moyamoya was diagnosed with a mean age at presentation of 34 years (range 23-40 years). RESULTS: In all but one patient bilateral affection was present at the time of diagnosis. All patients underwent direct and/or additional indirect revascularisation procedures. Twenty-one patients underwent bilateral revascularisation procedures. In two patients a unilateral procedure was performed. A direct STA-MCA bypass (superficial temporal artery branch - middle cerebral artery branch anastomosis) was performed in all patients. Additional direct STA-ACA bypass (STA - anterior cerebral artery branch anastomosis) was performed in 10 patients. Indirect arteriosynangiosis using the occipital artery was performed in the posterior cerebral artery (PCA) territory in 3 patients. The frontal branch of the STA was used for arteriosynangiosis in the frontal region in another 2 patients. Indirect frontal durasynangiosis was performed in 14 patients. The number and location of multiple revascularisation procedures was determined according to the angiographic findings as well as the site of decreased perfusion reserves seen on H(2)(15)O PET. A one stage revascularisation procedure was performed in 7 patients. Fourteen patients underwent two stage procedures. Following operation no complications were encountered in all but one adult patient who died postoperatively due to a massive middle cerebral artery infarct on the nonoperated side. CONCLUSIONS: As territorial hemodynamic disorder seems to be a characteristic in Moyamoya disease and/or syndrome, judging from our experience with European patients in our series, and several reports hitherto, treatment with multiple revascularisation procedures is considered to be justified.

Adolescent↗
PubMed2003

Somatomotor functional MRI in a large congenital arachnoid cyst.

The immature human brain, when damaged, is able to reorganise functionally. We performed functional MRI during eight different movements in a patient found incidentally to have an extensive, frontal, congenital arachnoid cyst, looking at which neural substrates contribute to motor control. Significant changes from the normal pattern of activation were seen in cortical and cerebellar areas which could not be accounted for by the space-occupying effect of the cyst alone. These findings in this asymptomatic patient with a congenital anomaly demonstrate an alternative organisation of the central motor system, with a preservation of neurological function.

Adult↗
PubMed2002

Intensive care management of patients with severe intracerebral haemorrhage after endovascular treatment of brain arteriovenous malformations.

We studied the impact of emergency neurosurgery and intensive care on the outcome for patients with severe intracerebral haemorrhage after endovascular treatment of brain arteriovenous malformations (AVMs). We reviewed the case notes of 18 patients with severe haemorrhage after embolisation of a brain AVM between 1986 and 2001. During this period the treatment changed: before 1993, these patients were not surgically treated, and they died, while after 1994, all patients underwent emergency surgery. We established a standardised protocol for emergency treatment and intensive care in May 1998, and emergency surgery was performed as soon as possible after the onset of symptoms of haemorrhage. Postoperative intensive care was according to a standardised regime. During these 15 years, 24 out of 605 patients undergoing 1066 interventions had a haemorrhage during or after the procedure, of which 18 were severe (3% of patients, 1.7% of interventions). All patients had a severe clinical deficit (mean Glasgow coma scale 4.2); eight had uni- or bilateral mydriasis. From 1989 to April 1998 four (31%) of 13 patients died, one (7.5%) remained in a vegetative state and eight (61.5%) made a good recovery. All five patients treated between 1998 and 2001 had a favourable outcome. The mean time from onset of the symptoms of haemorrhage to reaching the operation room was 129 min between 1989 and 1998 and 24 min between 1998 and 2001. Standardised emergency treatment and intensive care with early resuscitation, minimal radiological exploration before rapid surgery improved the outcome. A short time between the onset of the symptoms of haemorrhage and evacuation of the haematoma may be the most important factor for a favourable outcome.

Adult↗
PubMed2002

New methods for monitoring cerebral oxygenation and hemodynamics in patients with subarachnoid hemorrhage.

Radiographic cerebral vasospasm (CVS) after subarachnoid hemorrhage (SAH) do not reflect cerebral hemodynamics and oxygenation and may occur in the absence of clinical deficit and vice-versa. This report is to describe preliminary findings in further development of a non invasive method to estimate regional cerebral oxygenation and perfusion. Measurements were performed with a technique combining near infrared spectroscopy (NIRS) and indocyaningreen (ICG) dye dilution. Successful data analysis has been performed based on the decomposition in pulsatile and non-pulsatile components of NIRS absorption data collected before and during the passage of ICG through the vascular bed under the NIRS-detector. First measurements in patients with CVS suggest that the technique could become a powerful tool in the detection and treatment of CVS. This non invasive technique can be done at the bedside, it seems to be safe, easy to perform and less time-consuming compared to conventional techniques. The influence of extracerebral bone and surface tissue on cerebral NIRS signal has not been clarified yet. Therefore a new subdural NIRS probe has been developed, which gives the opportunity to measure directly the concentration of the chromophores in the brain without the influence of extracerebral contamination. In future comparative measurements with conventional NIRS probes on the scalp will allow to quantify and eliminate extracerebral contamination from the NIRS signal.

Adult↗
PubMed2001

Supracerebellar transtentorial approach to posterior temporomedial structures.

The supracerebellar transtentorial (SCTT) approach, a modification of the infratentorial supracerebellar approach, facilitates simple and minimally invasive access to posterior temporomedial structures without requiring retraction of the temporal or occipital lobe. The SCTT approach was used in 16 patients over a 3-year period. Eleven patients harbored tumors confined to, or located mainly within, the posterior hippocampal formation, three patients harbored aneurysms (one ruptured posterior cerebral artery [PCA] aneurysm at the P2-P3 junction, one ruptured giant PCA [P2] aneurysm, and one giant basilar artery-superior cerebellar artery aneurysm), one patient had juvenile-type moyamoya disease, and one patient suffered from medically intractable epilepsy. In these patients, the SCTT approach enabled tumor removal, aneurysm clipping, and vascular bypass procedures. The authors' experience suggests that this approach can be used routinely in treating lesions in the posterior temporomedial region.

Adolescent↗
PubMed2000

Cerebral oxygenation and systemic trauma related factors determining neurological outcome after brain injury.

We examined the relationship between clinical and radiological findings, cerebral oxygenation patterns during intensive care management, presence of systemic trauma related injuries and severity of illness in 50 patients (age: 32.3 +/- 12 years, GCS: 8 +/- 4) who were rescued from the accident scene within a 30 min period after trauma. Presence of systemic injuries was quantified using the Injury Severity Score (ISS) and severity of illness was scored using the Acute Physiology and Chronic Health Evaluation (APACHE II). Cerebral oxygenation parameters included continuous monitoring of jugular bulb oxygen saturation (SjvO(2)) for 12 840 h, and 2323 periodical blood sampling for measurement of arteriovenous differences in oxygen content (AVDO(2)), arteriovenous difference of lactate (AVDL) and lactate oxygen index (LOI). Fifteen patients (30%) presented with anisocoria or non-reacting pupils. Diffuse lesions on computed tomography (CT) were found in 34% of the patients and in 66% a mass lesion was removed. The mean ISS was 28 +/- 15.3 and 34 patients (68%) had an APACHE II score between 20 and 29 (mean 24 +/- 15). No statistically significant association between age (P = 0.45), gender (P = 0.83), initial Glasgow Coma Score (GCS) (P = 0.43), episodes of cerebral perfusion pressure (CPP) < 70 mm Hg (P = 0.8), ISS (P = 0.28), pupillary abnormalities (P = 0.57), initial CT findings (P = 0.74), APACHE II scores (P = 0. 36) and outcome could be demonstrated. The number of SjvO(2)desaturations (< 60%) was the only statistically significant factor associated with outcome (P = 0.05). The percentage of patients with poor neurological outcomes (GOS 1-3) was 38% in patients with no or one desaturation episode, and 57.6% in those with multiple desaturations. In conclusion, in patients who are resuscitated early and quickly transferred to the hospital, the number of SjvO(2)desaturations during intensive care management might be associated with outcome more strongly than other clinical and radiological features.

APACHE↗
PubMed1999

Correlation between jugular bulb oxygen saturation and partial pressure of brain tissue oxygen during CO2 and O2 reactivity tests in severely head-injured patients.

PURPOSE: To correlate the jugular bulb oxygen saturation (SjvO2) and brain tissue oxygen pressure (PbtO2) during carbon dioxide (CO2) and oxygen (O2) reactivity tests in severely head-injured patients. METHODS AND RESULTS: In nine patients (7 men, 2 women, age: 26 +/- 6.5 years, GCS of 6.5 +/- 2.9), a polarographic microcatheter (Clark-type) was inserted into nonlesioned white matter (frontal lobe). PbtO2 and SjvO2 were monitored simultaneously and cerebral vasoreactivity to CO2 and O2 was tested on days three, five and seven after injury. Simultaneous measurements of vasoreactivity by transcranial Doppler (TCD) were undertaken. A total of twenty-one CO2 and O2 reactivity tests were performed. Critical values of PbtO2 (< 15 mm Hg) during induced hyperventilation could be observed four times in two patients. High PbtO2 values up to 80 mm Hg were observed during hyperoxygenation (FiO2 100%). CO2 vasoreactivity by means of PbtO2 was absent in four tests in which measurements by TCD showed intact responses. A stronger correlation between SjvO2 and PbtO2 during the O2 reactivity tests was observed (r = 0.6, p < 0.001), in comparison to values obtained during the CO2 reactivity tests (r = 0.33, p < 0.001). In addition, there was no statistically significant correlation (r = 0.22, p = 0.26) between CO2 reactivity values measured by TCD (4.5 +/- 5.7%) and PbtO2 (3 +/- 2.8%). CONCLUSIONS: Correlation between SjvO2 and PbtO2 during CO2 reactivity test is low, even if significant differences between normo- and hyperventilation values are present. In comparison to SjvO2, monitoring of PbtO2 might more accurately detect possible focal ischaemic events during rapidly induced hyperventilation in severely head-injured patients. The CO2 vasoreactivity by means of changes in Vm MCA seems to be higher in comparison to changes of PbtO2. These observations lead to the hypothesis that vasoreactivity measured by TCD overestimates the cerebrovascular response to CO2.

Adolescent↗
PubMed1999

Experimental axonal injury triggers interleukin-6 mRNA, protein synthesis and release into cerebrospinal fluid.

Diffuse axonal injury is a frequent pathologic sequel of head trauma, which, despite its devastating consequences for the patients, remains to be fully elucidated. Here we studied the release of interleukin-6 (IL-6) into CSF and serum, as well as the expression of IL-6 messenger ribonucleic acid (mRNA) and protein in a weight drop model of axonal injury in the rat. The IL-6 activity was elevated in CSF within 1 hour and peaked between 2 and 4 hours, reaching maximal values of 82,108 pg/mL, and returned to control values after 24 hours. In serum, the levels of IL-6 remained below increased CSF levels and did not exceed 393 pg/mL. In situ hybridization demonstrated augmented IL-6 mRNA expression in several regions including cortical pyramidal cells, neurons in thalamic nuclei, and macrophages in the basal subarachnoid spaces. A weak constitutive expression of IL-6 protein was shown by immunohistochemical study in control brain. After injury, IL-6 increased at 1 hour and remained elevated through the first 24 hours, returning to normal afterward. Most cells producing IL-6 were cortical, thalamic, and hippocampal neurons as confirmed by staining for the neuronal marker NeuN. These results extend our previous studies showing IL-6 production in the cerebrospinal fluid of patients with severe head trauma and demonstrate that neurons are the main source of IL-6 after experimental axonal injury.

Animals↗
PubMed1999

Granulocyte colony-stimulating factor inhibits neutrophil apoptosis at the local site after severe head and thoracic injury.

BACKGROUND: Tissue injury from mechanical trauma often leads to secondary organ failure. Local accumulation of neutrophils and excessive release of toxic metabolites through inhibition of neutrophil apoptosis may be responsible for capillary leakage and irreversible damage of resident cells of injured tissues. METHODS: The purpose of this study was to examine the presence of apoptosis-inhibiting factors at the local site of tissue injury. Cerebrospinal fluid (CSF) from patients with severe head injury (n = 10; Abbreviated Injury Scale score, 4.5 +/- 0.2 points) and bronchoalveolar lavage fluid (BALF) from patients with serious chest trauma (n = 10; Abbreviated Injury Scale score, 4.1 +/- 0.1 points) were collected on days 1 and 3 after injury and compared with CSF (n = 5) and BALF (n = 16) obtained from patients undergoing elective orthopedic surgery. Neutrophils from healthy humans were incubated with 10% of CSF or BALF for 16 hours. Neutrophil apoptosis was determined by flow cytometric analysis of propidium iodide nuclear staining, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, and May-Grunwald-Giemsa staining. Levels of granulocyte colony-stimulating factor (G-CSF) in CSF and BALF were measured with enzyme-linked immunosorbent assay. RESULTS: CSF and BALF from injured patients significantly inhibited spontaneous neutrophil apoptosis of healthy humans compared with control samples, whereas respiratory burst activity was enhanced (p < 0.05). Moreover, CSF and BALF from injured patients contained increased (p < 0.05) amounts of G-CSF. Neutralization of G-CSF in CSF and BALF from injured patients using monoclonal anti-G-CSF antibody markedly (p < 0.05) reduced the apoptosis-inhibiting effect of those body fluids and decreased the respiratory burst. CONCLUSION: In patients with severe head or chest injury, G-CSF acts locally as a strong inhibitor of spontaneous neutrophil apoptosis, which may cause an increased destructive potential of neutrophils present in injured tissues.

Abbreviated Injury Scale↗
PubMed1999

Posterior circulation aneurysms. Technical strategies based on angiographic anatomical findings and the results of 60 recent consecutive cases.

Ninety-eight patients with aneurysms of the posterior circulation were admitted to our department from 1993 to 1997. Sixty of them underwent microsurgical treatment, mostly in the acute stage of subarachnoid hemorrhage. Peri- and intraoperative management were carried out according to a structured treatment strategy. Special aspects of surgical technique included extradural selective anterior clinoidectomy for basilar head aneurysms, lateral suboccipital craniotomy and partial condylectomy without laminectomy for aneurysms of the vertebral artery or posterior inferior cerebellar artery, and a trans-Sylvian approach, as used in selective amygdalohippocampectomy, for aneurysms of the posterior cerebral artery. A careful angiographic evaluation of the aneurysms in relation to the neighboring important arteries and bony structures was essential for optimal surgical planning. Forty-nine patients (82%) made a good recovery by 3 months after surgery. The mortality was 7%.

Acute Disease↗
PubMed1998

Thiopental in CSF and serum correlates with prolonged loss of cortical activity.

Barbiturate coma is initiated in brain-injured patients whenever elevated intracranial pressure remains unresponsive to other therapeutical strategies. However, barbiturates alter cortical activity resulting in difficulties in clinical evaluation. Therefore, we investigated the impact of long-term thiopental administration on responsiveness to exteroceptive stimuli in relation to pharmacokinetics of thiopental in CSF and serum. Long-term infusion increases thiopental levels which remain elevated for 6 and 9 days in CSF and serum, respectively, after termination of its administration. Prolonged unresponsiveness to exteroceptive stimuli correlates with persisting thiopental in CSF and serum. Thus, quantitative analysis of thiopental in serum becomes indispensable in predicting the length of drug-induced neurological impairment and in avoiding misinterpretation of the neurological status.

Adolescent↗
PubMed1998

Aneurysm surgery in the acute stage: results of structured treatment.

To evaluate the results of a structured treatment approach to aneurysm surgery in the acute stage, 150 consecutive patients with aneurysmal subarachnoid hemorrhage were studied, including 46 males and 104 females; World Federation of Neurological Surgeons grade I: 21 cases, II: 65, III: 41, IV: 23; day of operation < or = day 3: 103 cases, < or = day 7: 131. Patients underwent angiography on the day of admission or the next followed by surgery. The lamina terminalis and the membrane of Liliequest were routinely opened at surgery. The aneurysm neck was radically clipped after temporary clipping or trapping of the parent arteries. Intraoperative hemodynamic monitoring was used, and the craniotomies were closed without cisternal, epidural, or subgaleal drains. Nimodipine was given perioperatively (48 mg i.v./day for 10 to 14 days). Cases of symptomatic vasospasm were treated with selective intra-arterial administration of papaverine, sometimes combined with angioplasty. Outcome at discharge and 3 months later is good recovery in 61% and 75%, and death in 6% and 7%. The incidence of symptomatic vasospasm was 17%. Devastating vasospasms were observed in 5%. One-third of patients had mean flow velocities exceeding 120 cm/sec determined by transcranial Doppler sonography between days 4 and 14. Communicating hydrocephalus necessitating ventriculoperitoneal shunt occurred in 9%. Our results clearly show a favorable outcome compared with previous reports, especially with respect to the reduced occurrence of fatal vasospasm, hydrocephalus, and technical insufficiency.

Acute Disease↗