Biomedical subjects
Publications and source records attributed to J Reul.
A case of a duplication of the left vertebral artery associated with a premedullary epidermoid cyst at the level of the foramen magnum is described. The close proximity of the two malformative lesions in the present case and the overlap of the periods when such developmental abnormalities can arise suggest that they might be causally linked.
After long-standing malnutrition a 15-month-old boy with signs of kwashiorkor was admitted in a moribund state with serious hyponatraemic dehydration, hypothermia, somnolence, and signs of a pontine disconnection syndrome. Folic acid levels were below the detection level in the presence of normal cobalamin levels. MRI of the brain showed global volume loss and signal abnormalities on the T2-weighted images suggestive for central pontine myelinolysis (CPM). Brainstem acoustic evoked responses have remained normal. The serious metabolic and nutritional derangements required substitution of folic acid, vitamins and trace elements as well as slow correction of hyponatraemic dehydration with return of the sodium level over a period of four days. This therapeutic regimen resulted in complete neurological recovery. Follow-up MRI documented normalisation of the initial pathologic findings. The hypothesis was put forward linking the pathogenesis of CPM with the combination of folate depletion and superimposed hyponatraemic dehydration. The previously acquired folate depletion could affect normal appositional function of myelin basic protein molecules due to insufficient methylation of arginine in position 107. The subsequent development of intramyelinic edema and CPM will then be triggered by the superimposed hyponatraemic dehydration. The verification of this hypothesis requires further investigations.
Amongst 78 patients with either unilateral or bilateral (ponto-) cerebellar hypoplasia, atrophy or lesions on neuro-imaging (CT and/or MRI), 16 showed unilateral hypoplasia or lesions, 15 vermis defects, nine pontocerebellar hypoplasia, 10 non-progressive conditions with bilateral cerebellar hemisphere hypoplasia or lesions and 28 progressive cerebellar atrophy. Known genetic conditions did not occur with unilateral cerebellar involvement, whereas a high incidence of mostly autosomal recessively inherited diseases could be diagnosed in more than half of the patients with either pontocerebellar hypoplasia or progressive bilateral cerebellar atrophy. A minority of patients with vermis defects or non-progressive cerebellar hypoplasia suffered from genetic conditions. An overview of the literature is presented describing genetic and non-genetic syndromes, or metabolic disorders associated with cerebellar structural abnormalities. From these data, new proposals for improved diagnostic investigations will be presented.
OBJECTIVE: This study was designed to assess the intraluminal biological changes after endovascular coil occlusion of arterial aneurysms with detachable coils, to analyze the relationship between histological occlusion and mechanical packing density, and to evaluate the influence of perioperative anticoagulation on the occlusion rate. METHODS: In rabbits, 30 microsurgically produced arterial bifurcation aneurysms were occluded with coils (18 with platinum coils, electrically detached; 12 with tungsten coils, mechanically detached). Coils were placed until no further coils fit into the aneurysmal lumen and it was no longer filled with radiographic contrast material. The individual degree of occlusion was then determined by the "packing density" on the angiograms. Complete occlusion was considered only if no neck remnant was visible on the films. Anticoagulation during and 2 days after the treatment was performed in 11 cases. After an observation period ranging from 3 to 6 months, angiographic and histological analyses were performed to obtain control data. RESULTS: Complete occlusion was achieved in 9 cases, subtotal occlusion (i.e., > 95% occlusion, residual filling at the neck of the aneurysm) in 10 cases, and partial occlusion in 11 cases. Angiographically documented recanalization was detected in 14 aneurysms. In the remaining 16 aneurysms, the initially documented angiographic results were unchanged. A discrepancy between angiographic and pathological findings was frequently observed. Five of nine angiographically completely occluded aneurysms were recanalized. Endothelial-like tissue at the orifice of the aneurysm was able to be observed in only four of the nine initially completely occluded aneurysms. CONCLUSION: The results suggest that even dense packing does not always guarantee permanent occlusion, although there was a positive relationship between packing density and occlusion rate. Anticoagulation did not have any negative effect on the results.
PURPOSE: To evaluate the long-term outcome of endovascular occlusion of arterial aneurysms effected with metal coils. METHODS: Microsurgical methods were used to produce carotid bifurcation aneurysms in 20 rabbits and the radiologic and histologic changes were examined. Eight of these aneurysms were occluded with electrically detachable platinum coils (Guglielmi detachable coils [GDCs] and nine were treated with mechanically detachable tungsten coils (mechanical detachable system [MDS]). Three aneurysms remained untreated and served as controls. One animal died of embolic complications 12 hours after endovascular treatment. After observation periods of 3 to 6 months, the remaining animals were examined by intraarterial digital subtraction angiography and subsequent fixation and light and electron microscopy. RESULTS: Large open spaces without signs of thrombosis were found between the loops of the coil baskets in 12 aneurysms (six treated with GDCs and six treated with MDS) regardless of the observation period. In very densely packed aneurysms (four cases with complete occlusion as determined by angiographic criteria), the coil surfaces were for the most part covered by thin cell layers; however, complete endothelialization was never seen. In aneurysms with an initial partial occlusion of 70% to 90%, coil compaction and/or recanalization was a consistent finding. A comparison of the radiologic findings with the histologic aspect revealed that the degree of occlusion was often overrated on the radiographs (in eight of 17 cases). In general, the fibrous tissue reaction appeared to be slightly more pronounced in aneurysms occluded with tungsten coils. CONCLUSIONS: Platinum and tungsten coils were not always effective in causing endoluminal thrombosis leading to long-term occlusion by organized thrombus.
A renal transplant recipient with isolated cerebral aspergilloma 4 months after allograft transplantation is reported. On admission cerebral computed tomography showed a ring-enhancing mass in the left frontal hemisphere and aspirated purulent material revealed A. fumigatus hyphae. He was cured by short-term antifungal therapy and neurosurgical removal of the well demarcated lesion. He is still alive more than two years later and the renal transplant is well functioning. This is the first report of a renal transplant recipient with isolated cerebral aspergillosis without any relapse and only the third patient who has survived longer than 3 months. Early diagnostic procedures with rapid confirmation of aspergillus infection are pivotal for a benign clinical course.
Hemangioblastomas of the spinal cord and the brainstem make up 4% of all spinal tumors and are less common than cerebellar hemangioblastomas. CT and MRI are essential for preoperative diagnosis. Nevertheless, cerebral and spinal angiography are also mandatory, since they allow a detailed study of the vascular situation, which is decisive for exact planning of a surgical strategy. The purpose of this study was to evaluate the diagnostic and therapeutic factors which influence surgical morbidity and postoperative outcome. Twelve patients harbouring spinal(8 cases) or medullary (4 cases) hemangioblastomas, all symptomatic with sensorimotor deficits corresponding to the level of the lesion were evaluated. All patients were treated in our department between December 1989 and September 1994. Complete resection of the lesion was achieved in each case. Postoperatively, none of the patients showed deterioration. Nine patients had immediate postoperative improvement of neurological signs and symptoms; in three patients the initial neurological deficits remained unchanged during the in-patient period. Late postoperative outcome demonstrated a clear improvement; in only one patient was there no change of the clinical signs, while in the other 11 patients a significant improvement of pre-existing neurological deficits was experienced. We conclude that microsurgical resection of spinal and medullary hemangioblastomas with low morbidity is feasible.
Six patients with a dural arteriovenous fistula (DAVF) of the floor of the anterior cranial fossa underwent microsurgical treatment. Two of them were operated using a conventional frontobasal approach, and four using an interhemispheric approach. The interhemispheric approach offers the advantages of sparing the frontal sinus, minimizing frontal lobe retraction, and providing a visual angle perpendicular to the floor of the anterior fossa and an excellent view of the fistula located on the cribriform plate at the level of the foramen caecum. Using the interhemispheric route, the malformation was occluded in all the cases by dividing the vascular connection between the dura of the cribriform plate and the intradural draining vein. There were no complications related to the surgical procedure. This route avoids some disadvantages of the more frequently reported frontobasal approach. It is therefore a recommendable alternative for the management of frontal DAVFs.
The authors present a detailed account of the microsurgical production of bifurcation aneurysms in chinchilla rabbits for basic studies of endovascular coil embolization of aneurysms. End-to-side anastomoses of both common carotid arteries (CCAs) were performed, and a venous pouch was fitted into the newly created bifurcation. These experimental aneurysms closely mimic human cerebral aneurysms in size and hemodynamic features. Sixty-three animals underwent operation. Fifteen animals died in the course of the experiment and 15 were excluded because of a CCA occlusion within the carotid bifurcation. Electrical detachable platinum coils, also known as Guglielmi detachable coils (GDCs), and tungsten mechanical detachable coils (MDCs) were used for the endovascular occlusion of 26 bifurcation aneurysms (16 rabbits were treated with GDCs and 10 with MDCs). Initially, complete angiographic obliteration (95%-100% occlusion of the aneurysm) was achieved in nine rabbits and incomplete obliteration (< 95% occlusion) was seen in 17 animals. Final angiography 3 to 6 months later demonstrated complete occlusion in only four and partial occlusion in 22 aneurysms. At present, the histopathological examination of 17 embolized aneurysms has revealed incomplete obliteration of all aneurysms, even in those three cases that were thought to be completely embolized according to angiographic criteria. A general overestimation of the radiological degree of aneurysm obliteration was found.
Permanent neuropsychological changes such as memory disturbances and depression have been found in professional divers, even in those who have never had decompression sickness. The changes are probably the result of intravascular gas bubbles insufficient to cause acute symptoms. We examined amateur divers with long histories of self-contained underwater breathing apparatus diving by magnetic resonance imaging and compared them with normal controls. Hyperintense lesions of the subcortical cerebral white matter and degenerative changes of the cervical disks were significantly more common in the divers. 27 of 52 divers had a total of 86 focal hyperintensities versus 10 of 50 controls with 14 focal hyperintensities (p < 0.01). 32 divers had at least one degenerated intravertebral disc versus 9 controls (p < 0.0001). These results suggest that amateur divers are at risk of accumulating lesions in the central nervous system and in cartilage.
In 14 patients (eight men, six women; mean age 58 [31-72] years) with intracranial aneurysm (basilar artery in nine, anterior branches in five) the aneurysm was occluded by electrically detachable platinum coils, advanced into the aneurysm introduced via a percutaneously introduced catheter system, under local anaesthesia and fluoroscopic control. Ten patients had acute subarachnoid haemorrhage (stage II-IV). In two patients several sessions were required before complete occlusion was achieved. In one patient, with a basilar artery aneurysm, the aneurysmal wall was perforated (angiographically demonstrated contrast-medium extravasation), but this remained clinically asymptomatic. There has been no recurrence or renewed bleeding during a follow-up period of 6-12 months. The method is a highly promising addition to the micro-neurosurgical treatment of such aneurysms. However, as long-term results are still awaited, indications for using the method should be strict and only those patients should be so treated in whom operation would be associated with a high risk or who are inoperable.
This study was designed to compare the accuracy of magnetic resonance imaging (MRI), myelography and computed tomography in the assessment of degenerative cervical spinal stenosis. We prospectively examined a total of 75 spinal segments in 18 patients with suspected cervical spinal canal stenosis, using sagittal spin-echo and axial gradient-echo sequences generated by a 1.5 Tesla imager, conventional myelography, and computed tomography with intrathecal contrast medium (CT-myelography). The degree of stenosis was often overestimated using MRI. This error was most prominent in cases of severe stenosis but was significant with minor to moderate stenosis. In these cases, the clinical consequences of such an overestimation can be serious, because treatment is misdirected. The error is probably caused by pulsation of the cerebrospinal fluid and truncation artefact (Gibbs phenomenon). MRI at 1.5 Tesla is thus frequently inadequate for diagnostic assessment of degenerative cervical spinal stenosis. Myelography and myelographic CT are still useful for decisions on operative treatment, especially in cases of moderate stenosis. This may, however, not apply to imagers operating at 0.5 Tesla as below.
A new method to differentiate and classify normal and pathologic brain tissue in Magnetic Resonance Imaging (MRI) is introduced. With a special pulse sequence, exact T1 and T2 values are simultaneously acquired, where the T2 values may show a biexponential decay behavior. The automatic segmentation of the tissue is based on a histogram analysis of the multidimensional parameters. The tissue-characterizing parameters are stored in a database, which serves as an objective classification of different tissues. A pilot study with 15 healthy volunteers and 100 patients showed a good differentiation between normal tissue like white and gray matter, cerebrospinal fluid, muscle, and fat, thereby revealing a biexponential decay behavior of fat. Pathologic tissue-like edema and meningioma could be classified with high accuracy, while glioblastoma or astrocytoma were difficult to classify because of their non-homogeneous structures.
Four infants with obstructive hydrocephalus caused by space occupying third ventricle and mesencephalic cysts are reported. Despite immediate shunt insertion in all patients, there was either lack of clinical improvement or late onset of clinical deterioration. Neuroimaging (CT, MRI, and ventriculography) diagnosed the presence of non-communicating midline outpouchings of the CSF pathways causing obstruction of aqueductal CSF flow and brainstem signs. The cysts were of different origin. In one patient it was caused by a previous thalamic haemorrhage, in another patient by neonatal Escherichia coli meningoventriculitis. In two cases with obstructive hydrocephalus at birth, the aetiology is unclear. Direct puncture and drainage of the cysts led to clinical improvement. The cysts were poorly visualised on CT and could be misinterpreted as an enlarged third ventricle, simulating congenital aqueduct stenosis. Careful neuroradiological investigation is necessary to establish an accurate diagnosis and neurosurgical management. In such cases with hydrocephalus and persisting ventricular enlargement despite shunting, CT ventriculography is a useful tool.
BACKGROUND AND PURPOSE: Magnetic resonance imaging should have the potential to replace angiography in the diagnosis of dural sinus thrombosis. Concerning time-dependent signal changes of the thrombus, we intended to develop a standardized examination protocol for routine use in suspected dural sinus thrombosis. METHODS: The time-dependent signal changes of thrombosed dural sinuses were studied in 23 consecutive patients by multiplanar spin-echo and flow-sensitive sequences. Signal intensities and thrombus homogeneity were graded and related to the time after clinical onset and the results of the magnetic resonance angiography. RESULTS: Four stages of the thrombus evolution could be observed. The acute thrombosis (days 1 to 5) appeared strongly hypointense in T2-weighted images and isointense in spin density- and T1-weighted images. In the subacute stage (up to day 15) the thrombus signal was strongly hyperintense in T1- and T2-weighted images. The third stage began in the third week after clinical onset. The thrombus signal was decreased in all sequences and showed an increasing inhomogeneity. The fourth (late) stage was characterized by either the restitution of blood flow or the persistence of a residual thrombus. CONCLUSIONS: Each stage requires a different diagnostic approach. With the combined use of spin-echo and gradient-echo sequences, it is possible to make the diagnosis of acute thrombosis; in the second stage, multiplanar spin-echo sequences are sufficient. Diagnosis of dural sinus thrombosis can be established accurately with magnetic resonance imaging in the first two stages. However, the diagnosis of the later stages is difficult because of inhomogeneous signs of recanalization and flow phenomena. Therefore, a suspected older dural sinus thrombus still requires intra-arterial angiography as the primary diagnostic tool.
Surgery of lesions within or close to the central area of the brain always carries the risk of iatrogenic motor or sensory deficits. Functional localization by means of intraoperative direct stimulation of the motor area or by recording somatosensory evoked potentials (SSEP's) from the surface of the somatosensory cortex is believed to reduce the operative risk. The authors introduce the combination of dipole source analysis of scalp-recorded SSEP's with three-dimensional (3-D) magnetic resonance (MR) imaging as a tool for preoperative localization of the central sulcus. This provides information on both functional and structural localization for preoperative planning. Four repeated measurements of right and left median nerve SSEP's were obtained from 20 subjects. Dipole source analysis showed a retest reliability of the 3-D localization error of 2.9 +/- 2.0 mm. Compared to the MR evaluation, dipole source analysis was found to mark the central sulcus within 3 mm for 15 conditions (subjects x side of stimulation), while the 3-D MR measurement was accurate to within 6 mm for 10 conditions and 9 mm for 14 conditions. Dipole locations were confirmed in six patients who underwent surgery of the central region. With respect to this application, dipole source analysis combined with 3-D MR imaging appears to be a valuable tool for preoperative functional localization. The accuracy in localization will be further improved when realistic head models become available that can take into account individual head geometry. Further development of the proposed new method holds promise that evoked potentials and electroencephalography will gain greater use in presurgical functional localization.
Three days after having sustained a mild trauma to the head a seven-year-old boy developed seizure-like rotatory vertigo. Computed tomography, magnetic resonance imaging and cerebral angiography demonstrated a suprasellar space-occupying lesion. Pulmonary tuberculosis was discovered in subsequent diagnostic work-up. Cerebrospinal fluid examination was unremarkable except for immunological tests (tuberculostearic acid) which pointed to central nervous system (CNS) involvement so that a tuberculoma was suspected. The lesion decreased in size on tuberculostatic treatment (200 mg/d isoniazid, 200 mg/d rifampicin, two times 250 mg/d pyrazinamide). In the next 12 months there merely persisted a mild abnormality of the blood-brain barrier with a little contrast-medium uptake, which regressed in the following 6 months. The differential diagnosis between CNS tuberculosis and brain tumour or pyogenic abscess can be difficult in children if there are no pulmonary signs and/or the cerebrospinal fluid is normal.
Nine men with dural arteriovenous malformations (DAVM) at the base of the anterior cranial fossa are described. Four patients had intracerebral haemorrhage and four had seizures, associated with haemorrhage in two. In three cases the fistula was an incidental finding. In five cases the diagnosis could be made before angiography, on the basis of CT findings. Angiographically, venous drainage was always seen into ascending cortical veins. Five cases demonstrated drainage via the olfactory vein into the basal vein of Rosenthal; in four this way was the principal route of drainage. Five patients underwent surgery, the therapy of choice. One fistula closed spontaneously after angiography. Two patients refused treatment and one was not treated because of his poor general condition. Because arterial supply was usually bilateral, from small branches of the ophthalmic artery, embolisation seemed to be more dangerous. Compared to dural fistulae in other locations the DAVM of the anterior cranial fossa have a higher risk of complications and should be treated even if asymptomatic at the time of diagnosis.