Biomedical subjects
Publications and source records attributed to C Plets.
A case of hemangioblastoma of the right lateral ventricle is presented. Only five other cases of intraventricular hemangioblastoma have been reported. The literature on supratentorial intraventricular hemangioblastoma is reviewed.
The authors present a review of their experience with posterior fossa tumours in adults during a period of 20 years. Symptoms, physical findings, tumour histology, operative treatment and results are reviewed in 109 cases. The value of preoperative normalization of intracranial pressure by insertion of a ventriculo-subcutaneous drainage is discussed.
We compared the outcome of neurosurgical release of a tethered spinal cord in 20 children with the neurological evolution of 21 other children known iwth a tethered spinal cord on nuclear magnetic resonance scan (NMR). Neurosurgery yielded stabilisation of the symptoms without any lasting improvement. Pre-operative conservative medical treatment had to be continued in all operated children. Three of the 20 operated children are showing signs of retethering despite appropriate neurosurgery, indicating that retethering should be considered as a major and frequent complication. In the majority of our children, symptomatic (re)tethering was recognised by the appearance of increased tendon reflexes and a progressive pes cavus, suggestive of an upper motor neuron disease involvement.
External hydrocephalus was diagnosed using computed tomography in seven children presenting with macrocephaly. The value of different imaging techniques in distinguishing between subdural effusions and external hydrocephalus was investigated. High resolution ultrasonography combined with magnetic resonance imaging appeared to provide enough information to make a distinction between these two conditions. Radionuclide cisternography was still required to assess the flow pattern of the cerebrospinal fluid (CSF) which was important when placement of a lumboperitoneal shunt was considered.
The clinical value of three-dimensional time-of-flight magnetic resonance (MR) angiography was prospectively evaluated in 26 patients with congenital intracranial vascular lesions; 12 had arteriovenous malformations (AVMs), and 14 had venous angiomas. In the initial phase of the study the entire region of interest was imaged with one large acquisition volume (60-120-mm-thick slab). Later, the angiograms were obtained with adjacent but slightly overlapping, 30-mm-thick slabs, which clearly improved vascular detail. Gadolinium enhancement slightly improved depiction of veins but not of arteries. MR angiograms were compared with available conventional angiograms and MR studies. The topography of the AVM nidus was equally well appreciated on the MR as on the conventional angiograms. However, in six of 12 patients the hyperdynamic afferent arteries were incompletely shown on MR angiograms because of incomplete rephrasing. In three patients, venous drainage was also incompletely visualized. Compared with conventional MR studies, MR angiography offered the same detection rate but better anatomic insight. Thirteen of the 14 venous angiomas were also identified on MR angiograms. Detailed imaging, however, necessitated gadolinium enhancement and thin-slab acquisition.
The purpose of this study was to investigate the effect of propofol on cerebral blood flow, cerebral metabolism, and cerebrovascular autoregulatory capability. Seven anesthetized baboons were given propofol at three different infusion rates. An infusion of 3 mg.kg-1.h-1 caused minimal changes, but infusion rates of 6 and 12 mg.kg-1.h-1 decreased cerebral blood flow by 28% and 39%, respectively. The changes in cerebral metabolic rate of oxygen were not statistically significant. However, with the two higher infusion rates, there was a trend toward decrease, by 5% and 22%, respectively, for the cerebral metabolic rate of oxygen, and by 18% and 36% for the cerebral metabolic rate of glucose. A 25-30 mm Hg increase in arterial blood pressure had no influence on cerebral blood flow. Replacement of nitrous oxide by nitrogen had no significant influence on cerebral blood flow or metabolism. It is concluded that propofol causes a dose-dependent decrease in cerebral blood flow. However, the study does not prove that this decrease in cerebral blood flow is accompanied by the same degree of decrease in cerebral metabolism. Further studies are clearly needed to clarify propofol's influence on the coupling between cerebral metabolism and blood flow. The physiologic responsiveness of the cerebral circulation to alterations in arterial pressure is well preserved. Propofol appears to prevent the metabolic stimulation and increased cerebral blood flow that has been associated with the administration of nitrous oxide.
The Cushing, or ischemic response, is a useful mechanism in intracranial hypertension because it restores normal cerebral perfusion pressure and cerebral circulation. In patients with acute intracranial hypertension due to mass-expanding lesions such as brain edema, hydrocephalus or brain tumor, cerebral perfusion pressure decreases and plateau waves occur. In experimental animals, spontaneous or induced arterial hypertension can compensate for the reduction of cerebral perfusion pressure. The interrelation between arterial pressure, intracranial pressure and cerebral perfusion pressure in an experimental model of hydrocephalus in dogs was investigated. Plateau waves were preceded by a decrease in cerebral perfusion pressure and a Cushing response was seen 5 to 15 seconds before abolition of the wave. Arterial hypertension, induced by intravenous infusion of Aramin, restored cerebral perfusion pressure and intracranial pressure became normal. Arterial hypertension appears to be an efficient stimulus to abort plateau waves. Hypertensive patients in whom subarachnoid bleeding develops from ruptured aneurysm are at high risk of bleeding again and need antihypertensive treatment together with drainage of cerebrospinal fluid. Induced arterial hypertension is the most effective treatment of vasospasm but increases the danger of aneurysmal rebleeding and can only be safe after clipping of the aneurysm. This is one of the strongest arguments for early operation on cerebral aneurysms.
Glossopharyngeal neurinomas are rare entities. Only 16 cases have been described so far in the literature. Our experience with 2 cases demonstrates the non-specific and discrete clinical presentation of the ninth nerve neurinoma, but illustrates also some typical radiological aspects, enabling a more precise preoperative diagnosis. Two cases are presented and a survey of the literature is given.
Pseudoangiomatous dilatation of retromedullary veins at myelography was noted in three cases of intramedullary spinal cord tumours. This concerned two haemangioblastomas at levels Th8 and L1, respectively, and an ependymoma of the conus terminalis. MRI accurately demonstrated the tumoural mass, together with the enlarged and tortuous draining perimedullary veins. In patients with dilated vascular shadows on myelography, MRI should be performed before medullary angiography to differentiate between spinal vascular malformations and intramedullary tumours with enlarged draining veins.
Balloon embolization was attempted in 7 patients with posttraumatic carotid-cavernous fistulas. The procedure was successful in 4 patients and failed in 3 other. Two of these fistulas showed spontaneous regression after failed embolization. In one patient, premature detachment of the balloon led to cerebral infarction, but with total clinical recovery. One patient showed temporary palsy of the VIth cranial nerve after embolization.
Outpatient myelography with iohexol (Omnipaque) was performed in 150 patients. Side effects were noted in 28 patients (19%), with only 3 (2%) major complaints. It concerned 2 patients with severe and prolonged headache and one patient with seizures. Side effects were not more frequent in outpatient myelography than in reported series of hospitalized patients. The frequency of side effects was significantly lower with the use of iohexol than in comparable studies with metrizamide. Headache was the most frequent side effect, followed by an increase or exacerbation of ischiatiform pain, nausea and vomiting. Side effects were slightly more frequent in cervical myelography than in lumbar myelography and were not related to underlying pathology. It is concluded that outpatient myelography is feasable for as far as iohexol is used and patient surveillance is carefully organized.
Pre-operative embolization of juvenile nasopharyngeal angiofibroma was performed in 15 patients. The lesion was supplied by the internal carotid arteries (8 cases), by the internal maxillary artery (15 cases), the accessory meningeal artery (10 cases) and the ascending pharyngeal artery (10 cases). Superselective embolization of the external carotid artery feeders was performed with Ivalon particles, without neurological complications. Good control of per-operative blood loss was noted in 13 out of 15 cases, 2 patients presenting severe per-operative venous bleeding. Recurrence was noted in only one patient, which could be controlled by reembolization.
Between June 1984 and April 1988, 41 patients with severe posttraumatic lesions of the cervical spine between the C2-C3 and the C7-T1 level seen consecutively were treated by an anterior cervical fusion and osteosynthetic stabilization according to Caspar. These patients were prospectively studied. Seven patients had a bilateral facet dislocation, 5 a unilateral facet dislocation, 9 an anterior subluxation, 9 an anterior compression fracture, 5 a hangman's fracture, and 6 a hyperextension injury at a lower cervical level. From a neurological point of view, there were 12 patients with an initial complete transverse lesion and 14 with an incomplete transverse lesion, and the remaining 15 patients did not have any deficit initially. Four patients died during the first 3 months after the operation. In 38 patients good anatomical position was obtained, generally by the intraoperative use of the vertebral distractor of Caspar. In all patients excellent immediate postoperative stability of the spine was obtained, although in 2 patients a second operation was necessary a few days after the first one. Postoperatively all patients were "immobilized" by a soft collar for 3 months. Four patients with an initial complete transverse lesion showed some neurological recovery in the postoperative period, and all patients with an incomplete transverse lesion improved. There were no postoperative neurological disturbances in the group of patients who were neurologically normal from the beginning. The mean postoperative hospitalization time was 13.6 days. These results were compared to the results from the literature, concerning other conservative and operative treatments for posttraumatic lesions of the cervical spine.
MR imaging of an intracranial chordoma is described. The tumor appeared strongly hyperintense on T2 weighted images and moderately hypointense on T1 weighted images with a strong homogeneous contrast enhancement after IV administration of Gadolinium Dota. MR is superior to CT in delineating the tumor margins and in defining its relationship to the brainstem, optic chiasm and the vasculature, providing essential pre-operative information.
The authors retrospectively studied 32 neonates with macrocrania associated with a pericerebral collection. Differential diagnosis was made between external communicating hydrocephalus, atypical communicating hydrocephalus, subdural hygroma and local cerebral atrophy by means of CT scan, isotope cisternography, and isotope brain scintigraphy. Especially the two last examinations are of great interest. The most important arguments in favour of operation were a rapidly increasing and uncontrolled head circumference graph and a deterioration of the psychomotor development. In this regard, 13 out of 25 patients with external communicating hydrocephalus were operated upon (lumbo-peritoneal shunt). The analysis of the results reveals that rapidly increasing macrocrania is a good operative indication and gives excellent results but psychomotor deterioration turned into normal evolution only in 14% of the operated cases. Evacuation of a subdural hydroma first by external and followed later on by internal drainage normalizes the clinical picture.
MRI and CT were performed in 16 patients with 17 acoustic neurinomas. MRI was superior to CT in the detection of small acoustic neurinomas, in the demonstration of intracanalicular extension and in the differentiation with cerebellopontine angle meningiomas. Overall advantages of MRI over CT included better tissue contrast, absence of bone artifacts and easy multiplanar imaging.
In 7 patients with a brain tumor and intracranial hypertension treated by ventriculosubcutaneous drainage, intracranial pressure and cerebral perfusion pressure were continuously monitored during induction of anesthesia with fentanyl 1.5 micrograms/kg, propofol 2.5 mg/kg and vecuronium 0.1 mg/kg. End-tidal pCO2 was kept constant by manual ventilation and arterial pCO2 was verified before induction and before and after intubation. Five minutes after induction the patients were intubated and measurements continued for five more minutes. Mean arterial pressure decreased from 102 (+/- 9.8) mmHg to 57 (+/- 11.6) mmHg (p less than 0.01). Intracranial pressure did not change significantly before intubation. However in two patients intracranial pressure increased before intubation due to a significant rise in arterial pCO2. In 4 of the 7 patients an important increase to 25 (+/- 4.6) mmHg in intracranial pressure was observed during intubation. Cerebral perfusion pressure decreased from 88 (+/- 4.6) to 45 (+/- 9.8) mmHg (p less than 0.01) before intubation, but did not differ from the baseline during and after intubation. It is concluded that propofol 2.5 mg/kg in a bolus injection does not increase ICP but can produce a significant decrease of the cerebral perfusion pressure due to a marked decrease in mean arterial pressure in patients with a brain tumor.
Basal fluctuations of motilin and their correlation to intestinal motor activity were studied in five hypophysectomized (anterior lobe resection) patients. A cyclic pattern of motor activity identical to the one described in normal volunteers was observed. The mean interval between two activity fronts (AF) was 115 min, which is not significantly different from the normal length. Motilin levels were within the normal range, and fluctuations correlated with the occurrence of an AF. The mean difference between motilin levels 15 min before the AF and at the time of the start of the AF was +15 pM (P less than 0.05). For the levels 15 min after the AF the mean difference was -9 pM (P less than 0.05). These values correlate well with those reported by us in normal volunteers, in whom the mean differences were +11 pM and -14 pM, respectively. It is concluded that the adenohypophysis is not involved in the regulation of motilin levels or in the regulation of interdigestive motility in man.