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Biomedical subjects

E Markakis

Publications and source records attributed to E Markakis.

At least 37 records · Page 2Linked to original sources
PubMed1997

Intra-axial endophytic tumors in the pons and/or medulla oblongata. I. Symptoms, neuroradiological findings, and histopathology in 30 children.

Between August 1987 and June 1994 we operated upon 30 consecutive children suffering from endophytic intra-axial tumors located in the pons and/or medulla oblongata. We present the clinical findings, neuroradiological aspects and histopathological results recorded in these cases. Diagnostic tests included clinical examinations, neurophysiological tests and neuroradiological imaging [magnetic resonance tomography (MRT) in all cases, often combined with cranial computer tomography (CCT)]. The diagnosis was confirmed by histopathological examination of the tumor material obtained by open surgical exploration in all cases. We conclude that a short history and more horizontal growth within the pons are more valuable predictors of the histopathology than differentiation between focal or diffuse growth patterns. MRT has little predictive value for histopathological diagnosis in intra-axial brain stem tumors.

Adolescent↗
PubMed1997

Intra-axial endophytic tumors in the pons and/or medulla oblongata. II. Intraoperative findings, postoperative results, and 2-year follow up in 25 children.

Between July 1987 and June 1994 we operated upon 30 consecutive children suffering from endophytic intra-axial tumors located in the pons and/or medulla oblongata. The 25 children operated on between July 1987 and October 1993 whose postoperative course could be assessed for a minimum of 2 years after operation were included in this study. Operability of a brain stem tumor was shown to be independent of its size. A gross tumor resection between 80% and 100% could be performed in half these cases, and subtotal or partial resection in the other half. The radicality of resection was not influenced by tumor histopathology, but was dependent on intraoperative findings relating to its consistency, infiltration, and visibility. On follow up, 15 of the 25 children were found to have died within the period of 2 years. Two children died in the immediate postoperative period (at 2 days and 2 weeks after surgery), of acute brain stem swelling and an unsuspected bleeding disorder, respectively. The other 13 of these 15 children died of tumor progression between 1 and 19 months after operation, with a median survival time of 9 months. In the group of the surviving 10 children the histopathology was grade I astrocystoma in 6 cases, angioma in 2 cases, and grade II oligodendroglioma and grade II ependymoma in 1 case each. Postoperatively, most of the children showed some increase in their preoperative deficits, but recovered after 2-3 months. After 2 years, 10 of the 25 children who were followed up are alive and 9 of them attend regular school or kindergarten.

Adolescent↗
PubMed1997

Determination of the burr hole-site using the Brown-Roberts-Wells stereotactic system. A simple marking technique: technical note.

The authors describe a new tool-set with which the determination of the burr hole-site using the BRW-stereotactic system can be done on a non-sterile-washed head. The described attainment permits an increased security, not only reducing exposure of the operative field to a minimum but also shortening the operative length. The use of this tool-set for marking smaller superficial cortical processes is also possible.

Computer Simulation↗
PubMed1997

Using transcranial duplex sonography for monitoring vessel patency during surgery for intracranial aneurysms.

This article reports a method for reliable intraoperative monitoring of blood flow velocities in the basal cerebral arteries during clipping of intracerebral aneurysms. Transcranial color-coded duplex sonography provides practical integration of transcranial Doppler technology with real-time imaging capabilities through the intact human skull. With a computerized sonography system equipped with a 2.5-MHz probe in 50 healthy volunteers, the contralateral internal carotid artery, A1 and A2, as well as M1 and P1 vessels were identified and measured in most patients. In 13 patients undergoing dipping of intracranial aneurysms, the technique successfully imaged 12; it allowed definitive identification of vessels potentially threatened by clipping and not fully visible to the surgeon. Data were easily comparable to preoperative data. This noninvasive, repeatable neuroimaging technique provides useful intraoperative information about intracranial hemodynamics during dipping of intracranial aneurysms.

Adult↗
PubMed1996

Atypical and malignant meningiomas: evaluation of different radiological criteria based on CT and MRI.

The following are our results of a retrospective analysis of 214 patients, operated on meningiomas, in order to investigate radiological criteria of malignancy. Among these cases there were 31 patients with a histologically confirmed diagnosis of malignant subtypes. As uncertain signs of malignancy of ensuing radiological features are an irregular enhancement of contrast-media and the size of cerebral edema. Based upon CT and MR images we have developed a standardised, computerised evaluation method which enables us to study in detail the internal architecture of meningiomas.

Adult↗
PubMed1996

Symptomatology, surgical therapy and postoperative results of sphenoorbital, intraorbital-intracanalicular and optic sheath meningiomas.

A series of 7 patients with optic sheath meningiomas, 3 intracanalicular and intraorbital, 2 intraosseus meningiomas of the sphenoid wing involving the optic canal, and 4 sphenoorbital meningiomas were reported. The choice of a surgical approach to the orbit was appropriate to the location and size of the tumour relative to the optic nerve. The most common complaints were proptosis, reduction of visual acuity and paresis of eye muscles. Patients with optic sheath meningiomas are threatened postoperatively by visual loss whereas the high recurrence rate has to be taken into consideration in cases of sphenoorbital meningiomas.

Aged↗
PubMed1996

Intra-axial endophytic primitive neuroectodermal tumors in the pons: clinical, radiological, and immunohistochemical aspects in four children.

We present the clinical findings, radiological aspects, operative results, and histopathological features of four typical primitive neuroectodermal tumors (PNET) located in the pontine region in children. All the tumors had an endophytic intra-axial growth pattern. All the children had a short history of severe neurological deficits with involvement of the cranial nerves and pyramidal tract. MRI did not reveal any common feature of malignancy. Compared to our successful experience in operations of intra-axial endophytic brainstem tumors in a total of 32 children, the outcome was poor: all 4 children died within 13 months. We conclude that PNET occurring in the pons is not as rare as was believed, and, compared to PNET in other areas the prognosis is worse.

Actins↗
PubMed1996

Use of transcranial real-time ultrasonography for programming a shunt valve system.

For patients who suffer from hydrocephalus that is difficult to treat because of impaired intracranial compliance, a programmable shunt system may be a helpful alternative. However, especially during the first weeks after implantation, many radiological follow-up studies are necessary to achieve the optimum pressure level. The authors present the case of a 7-year-old boy who suffered from posthemorrhagic hydrocephalus and did not respond to conventional shunt valve systems. After implantation of a programmable shunt system, achieving the optimum craniospinal fluid (CSF) pressure level was difficult because the symptoms of over- and under-drainage were similar. Using transcranial real-time ultrasonography for evaluation of the diameter of the intracranial CSF spaces, we were able to adjust the correct pressure level without long-term intracranial pressure monitoring or daily computed tomography, which otherwise would have been necessary because of the ambiguous symptomatology. Transcranial real-time ultrasonography (TCUS) displays an image of the intracranial parenchyma and CSF spaces through the intact temporal bone and is a valuable, serially applicable bedside monitoring technique for patients requiring close imaging follow-up.

Cerebral Hemorrhage↗
PubMed1996

A stable positioning for patients requiring large calvarial exposure for surgical correction of cranial synostosis.

We present a simple and elegant method of positioning the child's head for repair of craniosynostosis. The Sugita head holder allows large exposure of the calvarium with little risk of injury, dislocation or extensive blood loss caused by venous compression. We operated upon 37 patients (age range, between 3 and 132 months, median age 7 months) and did not observe any complication or lesion caused by positioning.

Child↗
PubMed1996

Ketamine for analgosedative therapy in intensive care treatment of head-injured patients.

Ketamine was supposed to be contra-indicated in head injured patients although it possesses numerous advantages over other commonly used analgosedative drugs. Referring to these potential advantages and the lack of definitive data about its effect upon ICP, CPP or neurological development, we conducted a prospective study in which moderate or severely head injured patients (n = 35) were prospectively allocated to receive treatment either with a combination of ketamine or midazolam or fentanyl and midazolam. The initial dose was 6.5 mg/kg/day midazolam, 65 mg/kg/day ketamine or 65 micrograms/kg/day fentanyl and was later adjusted due to clinical requirements for a period of 3 to 14 days. Comparably high dosages of ketamine [corrected] have been found necessary (104 mg/kg/day). Four patients from the ketamine group (n = 17) and 5 from the control group (n = 18) were withdrawn during treatment due to persistent ICP above 25 mm Hg, countermeasured by barbiturate coma. Two more patients were withdrawn due to development of cardiovascular arrest (ketamine group) and multi organ failure. A comparison of the remaining patients revealed a lower requirement of catecholamines (significant on first day, p<0.05), an on average 8 mm Hg higher cerebral perfusion pressure and a 2 mm Hg higher intracranial pressure in the study [corrected] group. Enteral food intake was better in the study group. The outcome was comparable in both groups with or without inclusion of withdrawn patients.

Adolescent↗
PubMed1996

Immunoscintigraphy for the detection of brain abscesses.

The aim of this prospective study was to assess the diagnostic usefulness of a 99Tcm-anti-granulocyte antibody in the early differentiation of the aetiology of a ring-enhancing structure on computed tomography (CT) scans following neurosurgical intervention. In 26 patients (15 males, 11 females) aged 20-82 years with suspected intracranial infection, 29 SPET scans of the head were obtained 4-6 h following the intravenous injection of 555 MBq 99Tcm-anti-granulocyte antibody. The patients had antibiotic, antimycotic or corticosteroid therapy. The diagnosis was confirmed by surgery (19 cases) or subsequent CT/MRI (magnetic resonance imaging) scans and clinical follow-up (10 cases). The immunoscan was true-positive (abscess) in 6 (sensitivity = 100%), true-negative in 19 and false-positive in 4 (specificity 83%) cases. There was no obvious detrimental effect on the results due to the antibiotic, antimycotic or corticosteroid therapy. In conclusion, despite false-positive results, the 99Tcm-anti-granulocyte antibody is a useful tool in the early detection and exclusion of intracranial abscess after neurosurgical interventions.

Adult↗
PubMed1995

Bedside measurement of the third ventricle's diameter during episodes of arising intracranial pressure after head trauma. Using transcranial real-time sonography for a non-invasive examination of intracranial compensation mechanisms.

Using transcranial real-time sonography, changes in the axial diameter of the third ventricle during manoeuvres, which increased intracranial pressure (ICP), were measured in 28 patients with moderate to severe head injury. The measurements were correlated with ICP measured by epidural pressure monitoring. We observed reductions in diameter ranging from 0.3 to 1.1 mm with rises in intracranial pressure of at least 5 mm in 22 patients of whom only one died. In 6 additional patients, no changes in diameter were seen, and 5 of the 6 died. We interpret that poor outcome as a measurable inability for the brain to expel cerebrospinal fluid into extracerebral compartments during increased ICP. Transcranial real-time sonography may provide additional information about intracranial cerebral fluid dynamics and compliance.

Adolescent↗
PubMed1995

[Implantation of a phrenic stimulator in central respiratory paralysis].

Neoplastic or traumatic lesions of the brain stem or the upper spinal cord frequently cause respiratory insufficiency necessitating permanent mechanical ventilation. If the integrity of the diaphragm and its nerves is not affected, adequate ventilation can be achieved by electric stimulation of the phrenic nerves. Diaphragm pacing systems mean the patients can be independent of ventilator treatment. This is a psychological advantage for the patient, giving him or her the option of living in less specialized medical care units and perhaps even at home. CASE REPORT. We report the case of a 47-year-old man with a brain stem tumour, which was resected in large pieces. During the postoperative period an increasingly severe respiratory insufficiency developed, which finally made continuous mechanical ventilation necessary. After the viability of the phrenic nerves and contractility of the diaphragm had been shown by direct stimulation of the nerves to be still intact, it was decided that a diaphragm pacer system should be implanted. A "Diaphragm Pacer System S232 G" (Avery Laboratories, Glen Cove, N.Y., USA: external transmitter, antenna, implanted electrode and receiver) was implanted. Using a supraclavicular approach, phrenic nerve electrodes were placed around each nerve and connected with subcutaneous implants of radio signal receivers. Six days after implantation phrenic nerves were stimulated for a first short period. External antenna loops were taped to the skin over the implanted receiver sites (Fig. 3). The impulses produced by the transmitter were delivered via these antenna loops and led to contraction of the diaphragm, providing almost normal respiration. The duration of stimulation was increased stepwise from 1 h a day to full-time stimulation. Three weeks after implantation of the diaphragm pacer system the patient could be totally weaned from mechanical ventilation. After a further 2 weeks it was possible to discharge him from the intensive care unit, and he was then transferred to a rehabilitation centre.

Brain Neoplasms↗
PubMed1995

[Transcranial color-coded real time ultrasound. An improvement in patient monitoring in the neurosurgical intensive care unit?].

It is still not always possible to detect in time early intracranial complications in neurosurgical critical care patients. In addition, the exact definition of the lesion requires an often life-threatening transport to the CCT. Hence, there is still a need for improved bedside monitoring. New developments in ultrasound technique enable us not only to get a two-dimensional image of intracranial parenchymatous structures through the intact bone but also to visualise, by means of colour-coding, the blood flow the intracranial vessels. In 70 mostly neurotraumatised patients we found that this method is helpful in solving diagnostic or therapeutic problems without the patient having to leave the intensive care unit.

Adolescent↗
PubMed1994

Intra- and paraventricular arteriovenous malformations: symptomatology, neuroradiological diagnosis, surgical approach and postoperative results.

A series of 8 patients with para- and intraventricular arteriovenous malformations (AVM) is presented. Confirmed by histopathological examination or based upon their history all of them sustained recurrent intraventricular or intracerebral haemorrhages. Our results strongly recommend a surgical removal of these AVMs as a feasible and mandatory form of treatment. Conservative methods, e.g., embolisation or gamma beam irradiation leave the patient susceptible to rebleeding which often results in devastating neurological deficits. Total removal of the AVM with minimal surgical trauma was achieved in 7 patients under controlled hypotension and was facilitated by stereotactic guidance in two patients. Post surgical re-bleeding was not observed in any of our patients even though in one case only a subtotal resection of the angiomatous malformation was achieved. Based on our experience, we advocate an inspection of the lateral ventricle in order to avoid leaving any intraventricular portion of the vascular malformation behind. MRI investigation is recommended because the multiplanar images clarify the topographic-anatomic location and its relation to important surgical landmarks.

Adolescent↗
PubMed1994

Immunohistochemical and electronmicroscopic effects of a new 2.1 microns Ho:YAG laser on the rat brain.

Using an experimental animal model, the thermal single-pulse lesion derived from a mid-infrared 1.0 Joule 300 microns fibre-conducted Holmium: Yttrium-Aluminum-Garnet (Ho:YAG) laser was examined, with special emphasis on the orientation and depth of the tissue reaction. Performing biparietal craniotomy in Sprague-Dawley rats weighing 250-300 g, both hemispheres were targeted by different radiant exposures from 20 to 140 J/cm2 derived from a 600-800 microsecond single pulse. After survival periods of one to 30 days, the animals were sacrificed and both hemispheres were processed for light- and electronmicroscopic investigations. To resolve the depth and orientation of the tissue reaction regarding the localization of reactive astrocytes, we looked for the expression of glial proteins like glial fibrillary acidic protein (GFAP), Vimentin and S 100 with a three-step biotin-avidin immunoperoxidase method. Neuronal and secondary axonal damage was investigated by labelling Neurofilament and Synaptophysin. The tissue reaction beneath the ablated material, consisting of a vacuolation and coagulation zone resulting from heat diffusion, was further elucidated by localization of the heat shock protein (HSP 72 kilo Dalton). Revealing the extension of reactive astrocytes and the degree of the electronmicroscopically depicted glial oedema, the depth of the tissue damage was estimated to reach about 700 microns beneath laser excision. Since McKenzie predicted the depth of tissue damage beneath CO2 and YAG laser excisions in a theoretical mathematical model, the authors were able to develop a sensitive model for testing new laser systems and as a promising instrument for neurosurgery.

Aluminum↗
PubMed1991

Haemodynamic and endocrine effects of deliberate hypotension with magnesium sulphate for cerebral-aneurysm surgery.

Deliberate hypotension is widely used during cerebral-artery aneurysm surgery to facilitate clipping and to prevent rupture. A large number of drugs are commonly employed to achieve hypotension, but all have their specific drawbacks. We investigated the effects of magnesium-sulphate-induced hypotension on haemodynamics, as well as on plasma catecholamine and renin concentrations in 11 patients undergoing cerebral-aneurysm surgery. Magnesium sulphate lowered blood pressure by reducing systemic vascular resistance. There was no reflex tachycardia or rebound hypertension, and cardiac output was not decreased. Plasma renin activity increased during hypotension but the inhibitory effects of magnesium on angiotensin converting enzyme prevented angiotensin-II-associated hypertension. Plasma catecholamine concentrations increased moderately during hypotension. Renal perfusion was not impaired since diuresis remained constant or even improved during and after hypotension. Magnesium sulphate in high doses has major drawbacks, however, among which are enhanced neuromuscular blockade and delayed return of consciousness. Although the haemodynamic effects of magnesium sulphate during hypotension appear to be beneficial, these side-effects might limits its usefulness, particularly in neurosurgery. More research must be conducted before magnesium sulphate can be considered a routine method.

Adult↗