Biomedical subjects
Publications and source records attributed to L Mayfrank.
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.
The authors report about a 3-years experience with helical CT and 3-D surface reconstruction applied in neurosurgical patients. All examinations were performed in addition to preexisting diagnostic CT, MRI, or angiography. The aim of this study was to assess the clinical value of this method with regard to planning of the surgical approach to anterior, middle, and posterior skull base and spinal lesions. 75 examinations of 55 patients were analysed and ranked as follows: A = examination with significant additional information for neurosurgical planning of skull base or spinal procedures or for postoperative evaluation of the neurosurgical approach, B = examination with some useful information for the neurosurgical planning or postoperative control, however, without significant advantage as compared to established diagnostic methods, C = examination without significant additional information. Classification was performed independently by two experienced surgeons. Examinations of anterior, middle, and posterior skull base lesions including cerebral aneurysms were in the majority rated as helpful and significantly informative, (A = 21, B = 24, C = 9, n = 54). Three-dimensional imaging of the spine was of clinical value only in specific cases (A = 6, B = 6, C = 9, n = 21). The authors conclude that three-dimensional imaging is a valuable diagnostic tool for pre- and postoperative imaging of tumorous and vascular lesions adjacent to the skull base, allowing for optimal surgical approaches with minimal invasiveness.
BACKGROUND AND PURPOSE: Hemorrhagic ventricular dilatation (HVD) is a prominent feature of human intraventricular hemorrhage (IVH) and a strong indicator for poor outcome. We developed an IVH model to define the mechanisms responsible for HVD and to test the efficacy of intraventricular administration of tissue plasminogen activator (TPA) in the treatment of HVD. METHODS: Isolated IVH was produced in pigs by injecting 10 mL of blood simultaneously with thrombin into the right lateral ventricle. The treatment group received 1.5 mg of TPA after induction of IVH. Intraventricular blood volume and the volume of the lateral ventricles were assessed by CT after 90 minutes, 7 days, and 42 days. Intracranial pressure, the pressure-volume index, and the resistance to outflow of cerebrospinal fluid (R(out)) were measured 30 minutes and 7 days after IVH. RESULTS: After IVH, the volume of the lateral ventricles increased from 1.98 +/- 0.69 to 6.43 +/- 1.23 mL (P < .001). There was a linear relationship between ventricular and clot volume (P = .014). Initially, R(out) increased from 24.34 +/- 7.13 to 63.56 +/- 64.91 mm Hg/mL per minute (P < .001). After 7 days, restoration of normal cerebrospinal fluid circulation occurred, but the ventricles were still significantly enlarged (5.24 +/- 1.76 mL, P < .001) and filled with blood. Within 6 weeks, ventricular volume had returned to normal values, paralleled by complete clot resolution. Intraventricular administration of TPA significantly accelerated clot clearance and restoration of normal ventricle volume. CONCLUSIONS: These results suggest that intraventricular bleeding may cause impairment of cerebrospinal fluid circulation but that the mass effect of clots distending the ventricle walls is the most important mechanism responsible for HVD. This model closely imitates several prominent features of human IVH and may therefore be a useful tool for preclinical assessment of the efficacy and safety of treatment with TPA.
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.
The authors report their experiences gained from 19 patients with ventral or ventrolateral foramen magnum meningiomas operated on via the dorsolateral, suboccipital transcondylar access route. It is emphasized that the microsurgical management of these lesions includes two important aspects which increase the safety of the procedure: a meticulous preoperative planning based on the microanatomical details of each patient, as well as an individualized tailoring of the surgical approach. There were no deaths, and, in the past 5 years, no neurological complications in this series. Gross total removal of the tumour was achieved in each case. It is concluded that microsurgical removal of ventral or ventrolateral foramen magnum meningiomas with this technique constitutes a safe and recommendable procedure.
The glucose metabolism of 62 meningiomas was measured by fluorine -18-2-fluorodeoxyglucose (FDG) PET and correlated with proliferation rate (Ki-67 index) and tumor cellularity. The mean metabolic rate (MRGlu) for meningiomas was 0.26 +/- 0.13 mikromol/g/min (range 0.08-0.62 mikromol/g/min). The relative tumor FDG-uptake (Q-MRGlu) (tumor/contralateral cortex) of all meningiomas was calculated with 0.73 +/- 0.37 (0.24-1.79). Differences of Q-MRGlu were significant between the groups with high vs. low cellularity (p < 0.01), increased vs. normal proliferation rate (p < 0.025) and low (WHO grade I) vs. higher (WHO grades II, III) graded tumors. In recurrent meningiomas (14 tumors) the glucose metabolism was not increased. The data show that 18 FDG-PET is suitable to serve as non-invasive predictor of tumor growth characteristics in meningiomas.
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.
The choice of the surgical approach and operative technique for the management of cerebrospinal fluid (CSF) fistulas of the anterior cranial fossa are still a controversially discussed topic. Although "extracranial" approaches through the paranasal sinuses are becoming increasingly more popular among otolaryngologists and maxillo-facial surgeons, most neurosurgeons traditionally prefer the "intracranial" repair of CSF fistulas by a craniotomy. We present an approach through the frontal sinus for the repair of dural defects behind the posterior wall of the frontal sinus and at the floor of the anterior cranial fossa. The operative procedure comprises the following main steps: 1) exposure of the anterior wall of the frontal sinus by a bicoronal incision; 2) excision of the anterior wall without frontal burr holes; 3) bilateral removal of the posterior wall of the frontal sinus; 4) extradural inspection of the dura behind the frontal sinus and above the cribriform plate, ethmoidal roof, and orbital roof bilaterally; 5) closure of dural tears by direct suture and a periosteal graft; 6) reinsertion of the anterior wall of the frontal sinus and fixation with titanium micro plates. Twenty-five patients operated upon using this technique are described. The aetiology of the frontobasal lesion was traumatic in 23, and an ethmoid carcinoma in two. In all patients, the dural fistulas were successfully repaired during the initial procedure. One patient died from sudden circulatory arrest after an uneventful postoperative course of nine days. Otherwise, there were no postoperative complications. This technique affords atraumatic extradural inspection and repair of dural fistulas bilaterally behind the frontal sinus, and above the cribriform plate and the ethmoidal and orbital roofs with none or minimal brain retraction. It therefore allows early repair of CSF fistulas also in patients with severe brain injury. Although we consider the extradural closure of fistulas the method of choice, this approach also allows for a combined extradural-intradural procedure, thus enabling the surgeon to treat associated intradural pathologies, such as traumatic lesions or tumours of the frontal cranial base.
Aggressive treatment of patients with severe head injury increases the chance for survival and good functional outcome in most cases. To prevent irreversible cerebral lesions, the key point of treatment is the management of intracranial hypertension caused by intracranial hematomas, brain edema and impaired circulation of cerebrospinal fluid (CSF). Therapeutic standards are surgery of traumatic hematoma, osmotherapy and mild hyperventilation for brain edema, and CSF drainage. In highly elevated intracranial pressure (ICP) administration of barbiturates and forced hyperventilation can be considered.
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.
Eighteen consecutive patients with olfactory groove meningiomas, with diameters ranging from 1.5 to 7 cm, underwent microsurgical tumour resection using a unilateral frontal interhemispheric approach. Unilateral frontal craniotomy, superior to the frontal sinus, exposing the superior sagittal sinus was performed. The ipsilateral frontal lobe was gently retracted laterally, and the tumour resected through the gap between the falx and the medial aspect of the frontal lobe, anteriorly to the genu of the corpus callosum. Gross total tumour resection was achieved in all the patients. There was no evidence of damage to the frontal lobes, the anterior cerebral arteries or the optic system. Compared with the more commonly applied subfrontal route, the interhemispheric approach has the advantages of sparing the frontal sinuses and providing excellent overview of the dissection of the anterior cerebral arteries and the optic system, as well as for the resection of tumour invading the frontal cranial base.
Selection of the approach and technique for surgical repair of aneurysm of the vertebrobasilar artery system is mainly based on angiographic features. This report emphasizes that planning the surgical procedure should also include preoperative evaluation of the individual skull base configuration, as well as the relationship between aneurysm site and surrounding bony structures. These features are evaluated on thin slice CT scans using bone tissue algorithms and are particularly important for adequate exposure of distal vertebral artery (VA) or midline aneurysms, because these cases require drilling of the jugular tubercle. For the use of lateral approaches, the surgeon must be familiar with the extradural and intradural anatomy of the foramen magnum region and may rely on at least five anatomical landmarks for orientation during surgery: 1) the dural entrance of the vertebral artery; 2) the posterior condylar emissary vein; 3) the medial rim of the distal sigmoid sinus; 4) the hypoglossal canal; 5) the jugular tubercle. To increase the safety of the procedure, the authors recommend an individualized tailoring of the surgical approach according to the variable morphological situation of each patient.
We carried out 22 examinations to determine the value of three-dimensional (3D) volumetric CT (spiral CT) for planning neurosurgical procedures. All examinations were carried out on a of the first generation spiral CT. A tube model was used to investigate the influence of different parameter settings. Bolus injection of nonionic contrast medium was used when vessels or strongly enhancing tumours were to be delineated. 3D reconstructions were carried out using the integrated 3D software of the scanner. We found a table feed of 3 mm/s with a slice thickness of 2 mm and an increment of 1 mm to be suitable for most purposes. For larger regions of interest a table feed of 5 mm was the maximum which could be used without blurring of the 3D images. Particular advantages of 3D reconstructed spiral scanning were seen in the planning of approaches to the lower clivus, acquired or congenital bony abnormalities and when the relationship between vessels, tumour and bone was important.
The authors describe a method of real-time ultrasound-guided craniotomy for an approach to cerebral convexity lesions. During surgery, a specially designed high frequency (7.5 MHz) sector probe with a thin (11 mm), extended tip is used to image the cerebral lesion through a single burr-hole. The distance between burr-hole and lesion and the direction of the target are then determined from the ultrasound images, and craniotomy is completed with the aid of these parameters. Errors in the preoperative planning of the approach, which might result in incorrect placement of the craniotomy, can easily be recognized and corrected at an early stage of the operation, before the craniotomy has been completed. This technique greatly improves the accuracy in placing craniotomy flaps. Since the risk of misplacing the craniotomy is virtually eliminated in lesions which are identifiable on ultrasound images, the technique allows the surgeon to keep the skull opening as limited as possible.
In a series of 10 patients with stereotactically treated basal ganglia haematoma rtPA was used to dissolve remaining clots. Pre-operative haematoma volume ranged between 39 and 111 cm3 (average 56 cm3). Stereotactic aspiration alone yielded an average volume reduction of 60% (range 23 to 78%). Haematoma cavity was instillated with rtPA repeatedly beginning 24 hours after the stereotactic intervention. At the end of rtPA therapy between 2 and 4 days after onset of the haemorrhage 67 to 92% (average 84%) of the initial haematoma was removed in all patients. More than 80% of the pre-operative clot could be removed in 8 out of 10 patients between day 2 and 4. There were no signs of rtPA related toxicity. At the end of the follow-up period (between 4 and 17 months--mean 8 months) 6 patients were awake, oriented and with a residual hemiparesis able to live in their familiar environment. It is concluded that local rtPA instillation is an effective additional treatment to further resolution of deep seated intracerebral haematomas after stereotactic aspiration.
Twelve patients with severe intraventricular haemorrhage (IVH) underwent intraventricular thrombolysis with recombinant tissue plasminogen activator (rtPA). External ventricular drainage was performed in all patients within 24 hours of haemorrhage. Fibrinolytic therapy was started within 24 hours from the onset of symptoms in ten cases, and in two further cases after 48 hours and 5 days, respectively. Two to 5 mg of rtPA were injected via the ventricular catheter into one or both lateral ventricles. The injection was repeated at intervals ranging from 6 to 24 hours until CT scans demonstrated a substantial reduction of intraventricular blood. The total rtPA doses per patient ranged from 3 to 31 mg. CT scans showed a marked reduction of intraventricular blood and normalization of ventricular size within 24 to 48 hours from the beginning of the fibrinolytic therapy. Rapid reduction of elevated intracranial pressure by continuous diversion of cerebrospinal fluid could be achieved in all patients, because the ventricular catheters never became obstructed by clotted blood during the fibrinolytic therapy. During the period of treatment, the level of consciousness, as classified according to the Glasgow Coma Scale, improved from a mean value of 7 to 12. One fatal case of meningitis most probably due to the ventriculostomy was the only complication related to the treatment. This method of treatment might improve the prognosis in patients in whom a large intraventricular haematoma volume, ventricular dilatation, and impaired cerebrospinal fluid circulation are major determinants for the outcome.
This report describes a patient who developed bilateral chronic subdural haematomas after a stab injury to the thoracic meninges causing prolonged cerebrospinal fluid leakage into the epidural space. Diagnostic findings and therapeutic management are presented and possible pathogenic mechanisms are discussed. This case suggests that patients who have symptoms or signs of increased intracranial pressure after a penetrating spinal injury should be studied for subdural haematoma.
The value of imaging (cranial CT, cranial and abdominal sonography, plain film surveys) was examined retrospectively in 28 shunted children in whom 82 instances of suspected dysfunction arose. There were 23 obstructions, 12 dislocations, 1 disconnection, 6 infections, 3 overdrainages and 5 slit ventricle syndromes. Impaired absorption with ascites, a peritoneal liquor cyst and a seroma occurred in the peritoneal part of the shunt. Progressive dilatation of the ventricle system shown by CCT (89%) or ultrasound was the most sensitive sign of high-pressure hydrocephalus. Periventricular hypodensity and flattening of the gyri (15%) were found less often. An examination strategy in suspected shunt dysfunction is suggested on the basis of these findings.