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Biomedical subjects

D E Sakas

Publications and source records attributed to D E Sakas.

At least 19 recordsLinked to original sources
PubMed1998

Compound anterior cranial base fractures: classification using computerized tomography scanning as a basis for selection of patients for dural repair.

OBJECT: A classification is proposed to organize anterior cranial base fractures systematically according to their location and size. The goal of this study was to determine whether these two variables, irrespective of cerebrospinal fluid (CSF) rhinorrhea, are related to the long-term risk of posttraumatic meningitis and, hence, to standardize decision making concerning surgical repair of associated CSF fistulas. METHODS: With the aid of high-resolution thin-section coronal computerized tomography (CT) scanning, anterior cranial base fractures were classified into the following four major types: I, cribriform; II, frontoethmoidal; III, lateral frontal; and IV, complex (any combination of the other three types). Fractures with a maximum bone displacement that extended farther than 1 cm in any plane were classified as "large" and those less than 1 cm as "small." The authors used this classification in a study of 48 patients who were treated by conservative (20 patients) or surgical (28 patients) means. The results showed a gradation of risk: the fracture most likely to develop infection was a large cribriform (Type I) and the least likely was a small lateral frontal (Type II). Statistical analysis showed that the trend for an increased infection rate was related to the cumulative effect of three variables in the following order: 1) prolonged duration of rhinorrhea (analysis of variance [ANOVA], p = 0.017); 2) large size of fracture displacement (ANOVA, p = 0.079); and 3) fracture's proximity to the midline (ANOVA, p = 0.015). CONCLUSIONS: In this series, microsurgical repair was accompanied by a minimum complication rate. Hence, the authors recommend that patients with fractures that combine the aforementioned variables should be considered to have a high long-term risk of infection and their injury should be surgically repaired as soon as the posttraumatic edema has subsided. This applies to the following fractures: large cribriform (Type I) with transient rhinorrhea lasting 5 to 8 days and large frontoethmoidal (Type II) with prolonged rhinorrhea lasting longer than 8 days. Furthermore, the authors conclude that this classification can improve the management of posttraumatic CSF fistulas of the anterior cranial base and may provide insights into the mechanisms underlying their spontaneous repair and susceptibility to meningitis.

Adolescent↗
PubMed1997

Giant lumbar meningioma: a common tumour in an unusual location.

We report a 27-year-old woman with atypical sciatica due to a giant, rapidly growing, lumbar (T12-S1) meningioma. The unique features of this case are discussed and the importance of early investigation by MRI of patients with atypical low back pain and sciatica is highlighted.

Adult↗
PubMed1997

Neurological episodes after minor head injury and trigeminovascular activation.

Children appear particularly susceptible to severe but reversible neurological symptoms and/or signs after minor head injury; these include headache, confusion, drowsiness, vomiting, hemiparesis, cortical blindness, or seizures. Significantly, these neurological episodes are not associated with any identifiable structural brain abnormality on neuro-imaging. We propose that the cause of this condition is a reactive hyperaemia, a 'benign hyperaemic encephalopathy' mediated via activation of the trigeminovascular system.

Brain Edema↗
PubMed1997

Syndromes of posttraumatic neurological deterioration in children with no focal lesions revealed by cerebral imaging: evidence for a trigeminovascular pathophysiology.

PURPOSE: To explain the pathophysiology of the neurological deterioration that occurs after trivial head injuries in children and that is not caused by focal structural brain damage. Symptoms and/or signs include headache, confusion, drowsiness, vomiting, hemiparesis, cortical blindness, and seizures. CONCEPT: We propose that children who are susceptible to such neurological attacks have an unstable "trigeminovascular reflex," which is activated by craniofacial trauma. RATIONALE: After posttraumatic mechanical stimulation and activation of a defective or immature "excitable" trigeminovascular system, release of perivascular vasodilatory peptides causes cerebral hyperemia, which underlies the neurological deterioration. DISCUSSION: The original assumption that underlying cerebral edema was responsible for these phenomena has been proven incorrect by computed tomography. Subsequent proposed pathophysiological mechanisms include cortical spreading depression and trauma-triggered migraine. Recent research has implicated the trigeminovascular pathways in both these conditions and documented that head trauma can be associated with noncongestive cerebral hyperemia (i.e., not causing swelling). Thus, we propose that head trauma activates trigeminal nerve endings in face, scalp, dura, or cortex and, via a reflex, causes intracranial vasodilation and cerebral hyperemia. Drugs that block trigeminovascular activation might offer a benefit.

Blindness, Cortical↗
PubMed1996

Anterior callosotomy in the management of intractable epileptic seizures: significance of the extent of resection.

We report our series of twenty consecutive patients who underwent corpus callosotomy for medically intractable epilepsy. The follow-up is 6.7 +/- 0.5 years. Sixteen of 20 patients (80%) had a favourable outcome. Six patients have remained free of major generalized motor seizures, and ten further patients experienced significant sustained reduction in the severity and frequency of the seizures. The type of seizures associated with improved outcome were drop attacks, and generalized tonic-clonic seizures, in 11 of 13 (85%) and 14 of 18 (78%) of the patients, respectively. In order to establish the extent of necessary callosal resection to achieve seizure control, the outcome of patients was correlated with the extent of callosal sectioning on postoperative magnetic resonance imaging. This study confirms that an anterior callosal resection of two-thirds (or 65%) is sufficient to achieve significant improvement in seizure control with an acceptable morbidity in judiciously selected patients with medically intractable epilepsy. Results also suggest that the patient's history and clinical classification of the seizures have prognostic value as selection criteria for patients referred for this operation. In this series, no prognostic value was established for pre-operative electroencephalographic patterns, or neuroimaging findings.

Adolescent↗
PubMed1996

Experimental microneurosurgery of the trigeminal nerve: surgical technique for ganglionectomy and rhizotomy in the cat.

The techniques of two experimental surgical operations on the trigeminal nerve are described, namely, excision of the trigeminal ganglion (ganglionectomy) and division of the trigeminal root (rhizotomy), in the cat. These techniques have been developed with the specific aims of achieving the trigeminal lesion and also preserving a satisfactory postoperative quality of life for the animal in order to make it possible to study the long-term effects of trigeminal dennervation. To the best of our knowledge, a detailed description of such a surgical methodology is lacking; reporting of these procedures may facilitate future research on the trigeminal nerve.

Animals↗
PubMed1996

Anterior callosotomy for intractable epilepsy: outcome in a series of twenty patients.

This series reports 20 patients with intractable epilepsy who underwent corpus callosotomy during the period 1984-1993. The mean age of patients at the time of onset of seizures was 9 years and at the time of callosotomy 26 years. The seizure types were generalized tonic-clonic (18/20), drop attacks (13/20), absences (12/20) and complex partial seizures (8/20). The most common electroencephalographic (EEG) abnormalities were 'bilateral multiple spike and wave' (7/20), or 'generalized/multifocal spike and slow wave' (7/20). The follow-up was 5.6 (SD 0.6) years. Six patients have remained free of major generalized motor seizures and 10 additional patients experienced significant sustained reduction in the severity and frequency of the seizures. In total, 16 of 20 patients (80%) had a favourable outcome. The type of seizures associated with the most improved outcome were drop attacks, and generalized tonic-clonic seizures, in 11/13 and 14/18 of the patients, respectively. No relationship was established between seizure control and preoperative EEG patterns, computed tomography or magnetic resonance imaging findings. The most frequent complication was transient mild left hemiparesis that occurred in four patients. The mortality was nil. This study confirms the efficacy of corpus callosum division as a surgical option for selected patients with medically intractable epilepsy. In addition, results suggest that the history and clinical classification of the seizures have prognostic value as selection criteria for patients referred for this operation.

Adolescent↗
PubMed1996

Perfluorocarbons: recent developments and implications for neurosurgery.

Over the last 30 years, perfluorocarbons (PFCs) have been extensively investigated as oxygen carriers. Early studies indicated that these compounds could be used as blood substitutes or protective agents against ischemia. Adverse characteristics such as instability, short intravascular half-life, and uncertainties concerning possible toxicity precluded wide clinical application. However, advances in PFC technology have led to the development of improved second-generation oxygen carriers that incorporate well-tolerated emulsifiers (egg-yolk phospholipids). The authors review recent developments in this field and consider the potential role of PFCs in future neurosurgical practice. Diagnostic applications could include their use to assess cerebral blood flow, local oxygen tension, and brain metabolism or to achieve enhanced imaging and precise staging of inflammatory, neoplastic, or vascular disease processes by means of computerized tomography, ultrasonography, and magnetic resonance studies. Therapeutic applications could include cerebral protection, an adjunctive role in radiotherapy of malignant brain tumors, protection against air embolism, the preservation of organs for transplantation, and ventilatory support in head-injured patients with compromised lung function. In addition, PFCs have been used successfully as a tool in ophthalmic microsurgery and potentially they could fulfill a similar role in microneurosurgery.

Emulsions↗
PubMed1996

Perfluorochemical oxygen carriers: potential uses in neurosciences.

In this article we review recent developments in the field of "first-" and "second-generation" perfluorochemical (PFC) oxygen carriers. Particular emphasis is placed on the latest research and its implications regarding the clinical and experimental neurosciences. These compounds are ideally suited to the transportation of O2 within the vascular system. Two properties that facilitate their use in this respect are their very high solubility coefficients for O2 and CO2 and their biological inertness. Unfortunately, their widespread use has been limited by logistical difficulties associated particularly with their molecular behavior in vivo. However, advances in PFC technology have led to renewed interest. A potential role for second-generation PFCs in cerebral protection is exciting. Other possible significant applications are slowly becoming established in clinical practice. Currently under investigation are potential uses in the management of severe head injuries, radiotherapy or chemotherapy of malignant brain tumors, protection against air embolism, preservation of organs for transplantation, and as a tool in microsurgery of the retina or other parts of the CNS. Diagnostic neuroimaging applications could include the employment of PFCs as adjuncts in ultrasound, Doppler, computed tomography (CT), and magnetic resonance (MR) to achieve enhanced imaging and precise staging of inflammatory, neoplastic, and vascular disease processes. Research applications could include their use in magnetic resonance imaging and spectroscopy in assessing cerebral blood flow, local oxygen tension, and brain metabolism, in molecule-specific imaging, and as physiological markers of O2, ions, and pH.

Animals↗
PubMed1995

Posterior thecal lumbar disc herniation mimicking synovial cyst.

We describe a 70 year-old-patient with a rare, misleading presentation of lumbar disc prolapse, which on CT mimicked a synovial cyst. The whole nucleus pulposus had herniated, become sequestrated, and migrated behind the theca adjacent to the L4-5 facet joint. There was no continuity of the disc material with the intervertebral space. A fenestration was performed and the sequestrated disc material was found free of adhesions, and removed completely without difficulty. Histopathological examination confirmed the diagnosis. The patient had complete relief from his pain.

Aged↗
PubMed1995

One-year outcome following craniotomy for traumatic hematoma in patients with fixed dilated pupils.

Forty consecutive patients who underwent craniotomy for traumatic hematoma after developing bilateral fixed dilated pupils were studied to determine the factors influencing quality of survival and to seek criteria for management. Clinical and computerized tomography (CT) data were correlated with outcome 1 year after craniotomy. The functional recovery (good outcome or moderate disability) rate was 25%, with a mortality rate of 43%. Patients with subdural hematoma had a higher mortality rate (64%) compared to patients with extradural hematoma (18%) (chi-square test, p > 0.05). Other factors associated with markedly increased morbidity and mortality were increasing age (> 20 years), a prolonged interval (> 3 hours) between loss of pupillary reactivity and craniotomy, compression of basal cisterns, and presence of subarachnoid hemorrhage on CT. There were no survivors among patients exhibiting any of the following features: surgery 6 hours or more after bilateral loss of pupillary reactivity; age greater than 65 years; or absent motor response. Apart from the latter group, the nature of motor response (before pharmacological paralysis and intubation) was not a reliable predictor of mortality. The results suggest that the presence of an acute subdural hematoma is the single most important predictor of negative outcome in patients with bilateral unresponsive pupils.

Adolescent↗
PubMed1995

Focal cerebral hyperemia after focal head injury in humans: a benign phenomenon?

To assess the relationship between posttraumatic cerebral hyperemia and focal cerebral damage, the authors performed cerebral blood flow mapping studies by single-photon emission computerized tomography (SPECT) in 53 patients within 3 weeks of brain injury. Focal zones of hyperemia were present in 38% of patients. Hyperemia was correlated with clinical features and early computerized tomography (CT) and magnetic resonance (MR) imaging performed within 48 hours of the SPECT study and late CT and MR studies at 3 months. The hyperemia was observed primarily in structurally normal brain tissue (both gray and white matter), as revealed by CT and MR imaging, immediately adjacent to intraparenchymal or extracerebral focal lesions; it persisted for up to 10 days, but was never seen within the edematous pericontusional zones. The percentage of patients in the hyperemic group having brief (< 30 minutes) or no loss of consciousness was significantly higher than in the nonhyperemic group (twice as high, p < 0.05). Other clinical parameters were not significantly more common in the hyperemic group. The mortality of patients with focal hyperemia was lower than that of individuals without it, and the outcome of survivors with hyperemia was slightly better than patients without hyperemia. These results differ from the literature, which suggests that global post-traumatic hyperemia is primarily an acute, malignant phenomenon associated with increased intracranial pressure, profound unconsciousness, and poor outcome. The current results agree with more recent studies which show that posttraumatic hyperemia may occur across a wide spectrum of head injury severity and may be associated with favorable outcome.

Brain Concussion↗
PubMed1994

The perfluorocarbon fluoromethyloadamantane offers cerebral protection in a model of isovolemic hemodilution in rabbits.

BACKGROUND AND PURPOSE: Perfluorocarbons (PFCs) are considered promising cerebral protection agents because they could combine the beneficial effects of decreased blood viscosity with enhanced oxygen-carrying capacity and oxygen tissue delivery, but trials of PFCs as hemodilutants have been very limited. We evaluated fluoromethyloadamantane (FMA), a new perfluorocarbon compound, as an isovolemic hemodilutant and compared it with low-molecular-weight dextran 40 (D40) and a control group. METHODS: Through a transorbital craniectomy, the internal carotid, anterior, and middle cerebral arteries were coagulated to create a cerebral infarction in anesthetized, mechanically ventilated rabbits. No other experimental procedure was performed in control animals. In the two other groups, hemodilution was commenced 30 minutes after the arterial occlusion with either D40 or FMA. Hemodynamic parameters and brain and systemic temperature were monitored throughout the experiments. All animals were killed 6 hours after the arterial occlusion. RESULTS: Hemodynamic and metabolic parameters and blood oxygen content were not affected by the infusion of either FMA or D40. Brain and systemic temperature remained constant. The ratio of infarct volume to the hemispheric volume was 19.6 +/- 3.7% in the FMA group (n = 17), 19.9 +/- 4.6% in the D40 group (n = 16), and 40.3 +/- 5.7% in the control group (n = 17). The difference in infarct volume of both FMA and D40 animals compared with controls was statistically significant (P < .01) when tested with Student's t test. There was no significant difference between FMA and D40 groups. CONCLUSIONS: These results suggest that FMA has cerebral protective properties and should be purified, optimized, and further tested experimentally to develop a stable, efficient, and safe oxygen carrier, potentially suitable for clinical trials.

Adamantane↗
PubMed1994

Effects of lecithin-emulsified perfluorochemical compounds in ischemic brain injury.

A lecithin-emulsified "Pluronic F-68"-free perfluorochemical compound, named F-1,3-DMA, was tested as a new agent in the prevention of central nervous tissue ischemia. A permanent ischemia leading to cerebral infarction was induced after microsurgical exposure and occlusion of the internal carotid, anterior, and middle cerebral arteries in the rabbit. Following arterial occlusion, F-1,3-DMA was administered intravenously, in a solution rendered isotonic to plasma, over a 30 minute period. The F-1,3-DMA was well tolerated. Hemodynamic, cardiovascular and metabolic parameters were not affected by the infusion of F-1,3-DMA. Although PO2 remained virtually unchanged, animals treated with F-1,3-DMA (n = 9), had smaller infarct volume by 61 percent as compared to the control (n = 8) group (P < 0.04, Student's t-test). Histopathology did not reveal any F-1,3-DMA related damage in the non-infarcted brain. These results suggest that F-1,3-DMA has nervous tissue ischemia protective properties possibly because of microflow effects although O2 transport to "local" tissue may be enhanced as well. We believe that further research is necessary in order to make clinical trials of F-1,3-DMA possible.

Adamantane↗
PubMed1992

Successful treatment of intracerebral hydatid cysts with albendazole: case report and review of the literature.

Experience with the use of the drug albendazole in the management of cerebral hydatid disease is limited. We report a 33-year-old woman who was harboring multiple cerebral hydatid cysts and who was treated successfully with albendazole. No other treatment was used. The efficacy and the few reversible side effects of the drug are discussed, and the literature is reviewed.

Adult↗