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Biomedical subjects

E Markakis

Publications and source records attributed to E Markakis.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1990

DNA in chordomas of the clivus Blumenbachi.

Chordomas of the clivus are frequently denoted as malignant, mainly because of their propensity to recur, their crucial location and the fatal clinical course. Although microscopical examination commonly reveals pleomorphism, particularly of cells and nuclei, the histological assessment of malignancy is not always appropriate. The measurement of DNA could provide important information for a classification of their biological behavior (grading). Our examination of a chondroid chordoma revealed a typical diploid DNA curve within a "benign" 4C range concordant to the favorable course of this variant. Our second examination of a "typical" chordoma showed a wide pleomorphism of cell nuclei and moderate proliferation activity within a "low grade" scale. This pointed to a coming (fatal) recurrence 3.5 years after the first surgery. The third chordoma we examined presented an extraordinary 4C aneuploidy with hypertetraploid subpopulations and an increased number of bi- or poly-nucleated tumor cells with prominent nucleoli and some more mitotic figures. In 5 recurrences the DNA pattern remained principally unchanged.

Adult↗
PubMed1990

MRI diagnosis of aneurysmal bone cyst.

80-90% of individuals suffering from aneurysmal bone cyst (ABC) are children or adolescents. Primary ABC is a non-neoplastic lesion. Diagnostic assessment and detection of recurrence demands repeated plain x-rays or CT scans. These repeated radiographic examinations expose these young patients to large doses of ionizing radiation. Magnetic resonance imaging (MRI) is found to be an effective and reliable noninvasive technique for the diagnosis and follow-up controls of ABC.

Bone Cysts↗
PubMed1990

Surgical treatment of intramedullary tumors (spinal cord and medulla oblongata). Analysis of 16 cases.

From February 1987 to July 1988, 16 patients of our clinic with intramedullary tumors (seven astrocytomas, six ependymomas, two angiomas with intramedullary hematomyelia, and one angioblastoma of the medulla oblongata) underwent surgery. Radical excision was possible in six cases with tumors in the cervical and/or thoracic region as well as in two cases with tumors in the medulla oblongata. In the group of patients with cervical and/or thoracic tumors, seven showed improvement, up to complete remission of the neurological symptoms. From eight patients with tumors of the medulla oblongata, one patient showed an invasive tumor of the medulla oblongata and pons with corresponding extensive neurological deficits, and died six weeks after surgery. The neurologic symptoms of the other seven patients improved after a postoperative interval of at least six weeks. The surgical approach to tumors of the medulla oblongata or spinal cord was performed by midline incision. Occasionally, a dorsal root entry zone (DREZ) incision was used when the tumor showed strictly unilateral localization. Tumors of the rhomboid fossa were approached by a lateral incision to avoid damage to nuclear structures. The more rostral the tumor localization (medulla oblongata, pons), the less complete was the surgery: only one ependymoma of the medulla oblongata was accessible to total extirpation. The tumor dignity worsened with ascending level of tumor localization. As described generally in the literature, neurological deficits of those patients with tumors in the medulla oblongata increased in the first few postoperative weeks before they began to improve. Chemotherapy, radiation therapy or decompressive laminectomy by themselves only lead to an improvement and are, therefore, not recommended.

Adolescent↗
PubMed1990

[Frontobasal osteoplastic orbitotomy in surgical treatment of intraorbital processes].

A modified frontobasal osteoplastic orbitotomy with reconstruction of the orbital roof for operative approach to intraorbital processes of any localization and of different origin (tumors, foreign bodies etc.) will be presented. After a small trapezium-shaped frontal craniotomy, the superior orbital rim and the orbital roof are resected in one piece by means of an oscillating saw. This "orbital flap" has a triangular shape, its long tip pointing to the canal of the optic nerve. There is no significant retraction of the frontal lobe by using microscope. The orbital flap is replaced and fixed by two miniplates of Luhr. This technique facilitates a significantly better exposure of all intraorbital structures than other surgical approaches, reduces operative trauma, and has better postoperative functional results. In the last 4 years we have operated upon 16 cases by means of this method, which will be presented. Although in many cases the frontal sinus was involved there was only one infection. Most common postoperative complication (50%) has been lesion of the levator palpebrae muscle followed by ptosis, which usually improved after 4-6 weeks.

Adolescent↗
PubMed1990

[Reconstruction instead of resection: laminotomy and laminoplasty].

Spinal instability and deformity have to be kept in mind when performing laminectomies. The procedure described (laminotomy) results in a stable bony reconstruction of the spinal canal, which in addition may be enlarged (laminoplasty): Laminotomy is performed by means of an oscillating saw just medial of the pedicles, preserving the yellow and interspinous ligaments. The laminotomy specimen is removed en bloc. It can be refixed by means of vitallium plates, bridging the corresponding laminae and pedicles.

Adult↗
PubMed1989

Hemicranial attacks or permanent hemicrania--a sequel of upper cervical root compression.

After many years of unsuccessful conservative treatment 16 patients suffering from hemicrania are relieved of their pain or are improved by operative treatment. Hemicranial attacks or permanent hemicrania is found to be caused by upper cervical nerve root compression. Vascular compression of C2 (n = 9) or scar tissue surrounding C2 (n = 1) or C3 (n = 1) is the pathology identified in cases of cervicogenic headache or "cluster headache-like" headache. Compression attributable to tumor, prolapsed disc, or spondylotic changes is found to be a cause of permanent headache. Only in those patients with permanent headache are radiological or electrophysiological findings helpful for diagnosis. In patients with hemicranial attacks and compression of nerve root C2 (n = 10) or C3 (n = 1), only vasoactive tests (provoking or relieving pain) or local anaesthesia prove to be helpful in diagnosing and localizing the origin of pain. The operation involves freeing the nerve roots from vascular compression. In two patients the C2 ganglion is resected. Thirteen patients subsequently become pain free. In three patients, hemicrania improves. Four of the 16 patients experience a recurrence of pain after the decompressive operation. After additional thermorhizotomy two patients have no further complaints and one patient has improved. One patient can tolerate his pain with occasional analgesics. The problem of referred pain into the fronto-ocular region is discussed.

Adult↗
PubMed1989

[Microsurgical resection of small brain tumor processes with stereotactic control].

From 1986 we have operated upon 13 patients with small neoplasms localised deep intracerebrally or subcortically in the central region with stereotactic guidance. Exact localisation of the tumour was one aim, whereas another one was to avoid damaging functionally important structures. In the first two patients we performed stereotactic marking of the tumour after craniotomy. The following procedure was found to be particularly useful: - determination of the tumour coordinates and planning of the approach - approach by means of a stereotactically guided probe, if necessary biopsy - stereotactically guided introduction of the leading catheter - removal of the stereotactic frame and bedding of the patient - craniotomy and microsurgical resection of the tumour This surgical procedure may be performed in one or two separate sessions. The accuracy of microsurgical tumour resection achieved by stereotactic means resulted in a remarkable reduction of postoperative neurological deficits.

Adult↗
PubMed1988

Evaluation of intracranial pressure from transcranial Doppler studies in cerebral disease.

The extent to which estimations of intracranial pressure can be derived from intracranial flow patterns was studied. The blood flow velocity in the middle cerebral artery was recorded with the EME TC 2-64 transcranial Doppler (TCD) device in 26 patients suffering from various severe cerebral diseases. Simultaneously the mean intracranial pressure (ICP) was measured by means of an epidural device. Arterial carbon-dioxide tensions were monitored by blood gas analysis. In all patients it was observed that the middle cerebral artery flow patterns changed distinctly when the ICP increased; these changes were distinguished by a decrease of the mean flow velocity and an increase of the Pourcelot index. A good correlation between the ICP and the flow parameters (especially the product mean systemic arterial pressure x Pourcelot index/mean flow velocity) was found in a select group of 13 patients, in whom comparable initial conditions existed and in whom additional parameters influencing the TCD recordings could be kept constant (r = 0.873; P less than 0.001).

Adult↗
PubMed1988

Transethmoidal decompression of the optic nerve in the case of craniocerebral trauma.

Over a period of ten years, 39 patients who had suffered optic nerve compression after a craniocerebral trauma underwent transethmoidal decompression surgery. The operation was performed bilaterally on 5 patients. Fifty percent of patients involved suffered a blunt head or brain injury, the others brain compression or contusion. On the side of optic nerve compression, we found specific signs and symptoms of the compression such as negative or sluggish direct light reaction of the pupil, wounds on the lateral side of the eyebrow, bleeding from the nose, eyelid hematoma, skull fractures and intracranial hematomas. Since radiological and intraoperative findings were the same in only 67% of cases ophthalmological findings such as lack of direct pupil reaction occurring together with preserved consensual light reaction and progressive loss of vision after a traumatic incident are used as guideline for performing transethmoidal decompression of the optic nerve. Surgery produced restitution of visual function in about 10% more cases than conservative therapy reported in the literature.

Adolescent↗
PubMed1988

Impulse cytophotometric DNA analysis in pituitary adenomas.

Flow cytometric DNA analysis was carried out on 32 microsurgically removed pituitary adenomas. Additionally, the histograms of tumor cell nuclei of 7 patients were compared with those of the cultured cells from the same tumor samples. The tumors were classified into 3 groups according to the proliferation index (PI) of the flow cytometric results: 1) tumors with DNA patterns of slow proliferation (PI under 10), to which the majority of the examined pituitary adenomas belonged; 2) pituitary adenomas with diploid karyograms and PI values from 10 to 15; 3) diploid or aneuploid karyograms with PI values above 15. The third group were characterized histologically by increased chromatin content, nuclear polymorphism, mitoses, and extrapituitary infiltration of the tumor cells, and were, therefore, no longer benign. However, there was no direct relationship between the intensity of hormone secretory activity of the tumors and DNA ploidy. Cultured adenoma cells examined by flow cytometry remained stable in all cases but one.

Adenoma↗
PubMed1985

Brain abscess in childhood.

The author review 10 years' experience in managing brain abscess in childhood: 19 cases were treated in children from 1 to 18 years old. The etiology was rhinogenic in 5 cases, congenital heart disease in 5, hematogenous in 3, traumatic in 3, postoperative in 1, and unknown in 3 cases. Brain abscesses that developed by direct spread were located nearby the source, whereas metastatic abscesses (such as cardiogenic or hematogenous) in most cases spread via the vertebral-basilar system, usually developing in the parieto-occipital regions. Four of the 5 cases with multiple abscesses were cardiogenic and one hematogenous. The most important neurological signs were paresis (10 cases) and cranial nerve involvement (10 cases). Six abscesses were sterile and 6 grew aerobic and 6 anaerobic bacteria. In one case, aerobic as well as anaerobic bacteria were found. Fifteen patients were treated preoperatively with antibiotics. The treatment was operative in 17 cases. In two cases, gravely ill on admission, no surgical treatment was given. The etiology, localization, bacteriology, surgical methods, and results in those cases are discussed.

Adolescent↗
PubMed1982

[On the biological behaviour of the rare malignant plexus papilloma in childhood: long-term observations in two operated cases].

Only a few verified cases of malignant papilloma of the choroid plexus have been described in the literature. The biological nature and prognosis of those tumours are not well known. Two cases of our own material are presented in whom large tumours of the lateral ventricles have been removed. One patient was 9 months and the other seven years old at the time of operation. The clinical follow-up period was seven years. Computer-tomography controls did not reveal any sign of recurrence. The published cases are reviewed until 1981. Their clinical aspects, the histological features and the nature of these rare tumours are discussed.

Cerebral Ventricle Neoplasms↗
PubMed1981

Neurological signs and operative indication by agenesis of the perisylvian region: a study of 13 operated cases.

The article reports on 13 cases of agenesis of the perisylvian region in patients aged 2 to 53 years. The agenesis occurred in the temporal operculum in 7 cases, in the frontal operculum in 5 cases and the whole fronto-parieto-temporal region in one case. The agenesis was always associated with space requiring arachnoidal cysts. Symphyses and obstruction of the flow of the basal CSF spaces were also seen. In 85% of the patients were males. The patients tend to decompensate after light cerebrocranial trauma, and in many cases surgery reveals a subdural haematoma which fills the aplastic region, due to detachment of the exposed cerebral veins effecting basal drainage. In the remaining cases, surgery was performed because of general signs of cerebral compression, exarcebation of an existing disease associated with attacks, or because of the space occupying character of the concomitant arachnoidal cysts. In patients wit agenesis of the perisylvian region without space occupying arachnoidal cysts, surgery is not performed for the time being, instead, regular neurological and CAT-Scan control is effected.

Adolescent↗
PubMed1979

[Opercular aplasia (author's transl)].

The article reports on 11 cases of opercular aplasia in patients aged 5 to 44 years. Aplasia occurred to a greater extent in the frontal operculum than in the temporal operculum, and was always associated with space-requiring arachnoidal cysts. Symphyses and obstruction of the flow of the basal CSF spaces were also seen. In 91% of the cases, the aplasia was localized on the left side, 91% of the patients were males. The patients tend to decompensate after a cerebrocranial trauma, and in many cases surgery reveals a subdural haematoma which fills the aplastic region, due to detachment of the exposed cerebral veins effecting basal drainage. In the remaining cases, surgery was performed because of general signs of cerebral compression, exacerbation of an existing disease associated with attacks, or because of the space-occupying character of the concomitant arachnoidal cysts. In patients with opercular aplasia without space-occupying arachnoidal cysts, surgery is not performed for the time being; instead, regular neurological and CT control is effected.

Adolescent↗