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Biomedical subjects

S M Papadopoulos

Publications and source records attributed to S M Papadopoulos.

46 records · Page 3Linked to original sources
PubMed1990

Unusual cause of 'piriformis muscle syndrome'.

The piriformis muscle syndrome is a controversial "clinical" syndrome primarily characterized by signs and symptoms of sciatic nerve compression at the region of the piriformis muscle as it passes through the greater sciatic notch. The syndrome is often referred to; however, cases are rarely reported, and it is generally an uncommon diagnosis. Of those cases reported, the incidence is six times more frequent in females than in males, and is typically temporally related to minor pelvic or buttock trauma. We describe a case of a 40-year-old woman presenting with signs and symptoms suggestive of piriformis muscle syndrome following a gynecologic procedure performed in the dorsal lithotomy position. Electromyographic findings were consistent with this clinical entity. Operative exploration, however, revealed the source of neural compression to be a pseudoaneurysm of the inferior gluteal artery adjacent to the piriformis muscle. The diagnostic features of this clinical syndrome are discussed.

Adult↗
PubMed1990

Characterization of contractile responses to endothelin in human cerebral arteries: implications for cerebral vasospasm.

Cerebral vascular tone is modulated, at least in part, by the vascular endothelium. This probably results from a balance between the release of the endothelium-derived relaxing factor(s) and the endothelium-derived constricting factor(s) (e.g., endothelin). The time course of the induction and the decay of these mutually antagonizing substances differ considerably. Endothelium-derived relaxing factor is probably involved in rapid changes in vascular tone whereas endothelin may be more important in long-term modulation. We have studied the vasoconstrictor properties of endothelin in human cerebral artery strips. Endothelin typically produced an intense, sustained increae in tone over a dose range similar to that seen with other vasoconstrictor substances such as serotonin and prostaglandin F2 alpha (ED50 = 10(-8) M). The response was resistant to selective antagonists of norephinephrine, serotonin, isoproterenol, histamine, acetycholine, and angiotensin II. Only sodium nitroprusside, verapamil, and a disulfide bond reducing agent (dithiothreitol) inhibited the response. The physiological properties of this response are similar to those of a vasoconstrictor protein found in cerebrospinal fluid from patients with cerebral vasospasm after subarachnoid hemorrhage. The time course of the induction of endothelin production is consistent with the temporal sequence of vasospasm, further supporting the hypothesis that endothelin may be involved in this pathological process.

Cerebral Arteries↗
PubMed1989

Anterior cervical osteophytes as a cause of progressive dysphagia.

An uncommon cause of progressive dysphagia may be large cervical osteophytes impinging upon the cervical esophagus. Dysphagia may be due to the mechanical mass effect of a large anterior osteophyte, trapping the esophagus opposite a fixed point such as the cricoid cartilage, or a local inflammatory reaction resulting in cricopharyngeal spasm. We report three patients with progressive dysphagia due to large anterior cervical osteophytes. All three patients were treated with anterior cervical approach with removal of the osteophytes without fusion. A review of the literature in addition to the specific case histories, video fluoroscopic and radiographic findings are presented.

Aged↗
PubMed1989

Mechanical prophylaxis of venous thrombosis in patients undergoing craniotomy: a randomized trial.

A randomized, prospective clinical trial of 70 patients undergoing craniotomy was performed to compare and evaluate two forms of mechanical prophylaxis of deep vein thrombosis. Thirty-eight patients received antiembolism stockings, whereas 32 patients received external pneumatic compression. Prophylaxis was begun preoperatively and continued intraoperatively and post-operatively until the patients were ambulatory. Impedance plethysmography was used to detect deep vein thrombosis both preoperatively and postoperatively. Two patients, one from each group, developed thromboembolic complications postoperatively. Impedance plethysmography showed false-positive findings in two additional patients. There were no deaths. The data suggest that either form of mechanical prophylaxis is effective against the development of deep vein thrombosis in this high-risk patient population.

Clinical Trials as Topic↗
PubMed1989

A simple device for controlling suction force in neurosurgical operations.

A simple and inexpensive device for controlling suction force in neurosurgical operations is described. This device is interposed in the suction tubing on the sterile surgical field. This has the advantage of allowing the surgeon to alter the suction force quickly and easily, according to his or her preference. The total cost is minimal, and the device may be assembled with supplies currently available in most operating rooms.

Humans↗
PubMed1989

Pseudoaneurysm of the inferior gluteal artery presenting as sciatic nerve compression.

A pseudoaneurysm of the inferior gluteal artery presenting as sciatic nerve compression is reported in a 40-year-old woman. Following a transvaginal needle biopsy for endometriosis, the patient developed left sciatic pain and a nonpulsatile mass palpable in the left buttock thought to represent a pyriformis hematoma. Sequential computed tomographic scans were consistent with this diagnosis. Persistent pain and progression of neurological deficits led to surgical exploration. Posterior exposure of the pyriformis muscle and proximal sciatic nerve revealed a large pseudoaneurysm of the inferior gluteal artery compressing the nerve. A laparotomy was performed and the internal iliac artery was ligated, followed by evacuation of the aneurysm contents and repair of the aneurysm neck via a posterior approach. The patient has remained pain-free with progressive improvement in neurological function after 1 year follow-up. Aneurysms of the gluteal artery are unusual, predominantly occur after significant pelvic trauma, and rarely present as sciatica. Pertinent aspects of the patient history and clinical findings are atypical for discogenic sciatica. Because of the rarity of this entity, preoperative diagnosis is usually not achieved. Angiography or magnetic resonance imaging should be performed in patients with atypical sciatica and a mass in the region of the proximal sciatic nerve, particularly after trauma.

Adult↗
PubMed1989

Cerebral edema induced by arachidonic acid: role of leukocytes and 5-lipoxygenase products.

Arachidonic acid is released from cellular phospholipid membranes after brain injury associated with vasogenic edema. Intracerebral injection of arachidonic acid results in rapid breakdown of the blood-brain barrier, followed by an increase in brain water and sodium content. This effect is diminished by a 5-lipoxygenase inhibitor, but is unaffected by indomethacin, an inhibitor of cyclooxygenase. Leukocytes are rich in 5-lipoxygenase and mediate posttraumatic extracellular edema in other tissues. We sought to determine whether leukocytes are necessary for arachidonic acid-induced vasogenic edema and whether they are the primary source of 5-lipoxygenase activity. Intracerebral injection of arachidonic acid (10 micrograms) was performed in 21 rats divided into three groups. One hour after injection, the area of Evans blue stain extravasation on the corona slice through the needle tract was quantitated by polar planimetry and taken as a measure of blood-brain barrier permeability. Control animals (n = 7) had a 3.44 +/- 0.19 mm2 area of Evans blue cortical stain. Rats (n = 7) pretreated with a lipoxygenase inhibitor (BW755C) had a significant decrease (P less than 0.05) in the area of Evans blue extravasation was not significantly different from that seen in the control animals. Intracerebral injection of saline or eicosapentaenoic acid showed only minimal staining along the needle tract (0.14 +/- 0.08 mm2). We have confirmed the role of the 5-lipoxygenase products in arachidonic acid-induced vasogenic edema. The primary source of cerebral 5-lipoxygenase activity does not appear to be in leukocytes and is most likely within the brain parenchyma.

Animals↗
PubMed1987

Recombinant human tissue-type plasminogen activator therapy in acute thromboembolic stroke.

Systemic fibrinolytic therapy for acute stroke is no longer recommended because of resulting systemic fibrinolysis and the risk of intracerebral hemorrhage. Human tissue-type plasminogen activator (TPA) is a native enzyme that converts plasminogen to plasmin with subsequent clot lysis. The affinity for plasminogen is increased several-fold when the substrate is bound to fibrin. At appropriate dosage, "clot-specific" thrombolysis may be achieved at the surface of the thrombus without creating systemic fibrinolysis. The authors designed a study to evaluate the effect of intravenous TPA administered 2 hours after acute thromboembolic stroke in rats. This time course was chosen to simulate an analogous clinical situation. Middle cerebral artery embolic stroke was caused by intracarotid injection of 0.025 cc of human blood clot in 16 rats. Regional cerebral blood flow, measured by the hydrogen clearance technique, and electroencephalographic (EEG) recordings were obtained every 30 minutes for 5 hours after thromboembolism. Eight rats received a 1-hour infusion of intravenous TPA (1.5 mg/kg) 2 hours after injection of emboli. Ipsilateral blood flow increased significantly within 30 minutes after intravenous TPA and reached preembolic levels within 60 minutes. Blood flow did not improve in the eight control rats throughout the experiment. Power spectral analysis of the EEG recordings showed improvement in the treated group compared to the control group. Postmortem angiography revealed proximal middle cerebral artery occlusion in control animals and patent middle cerebral arteries in TPA-treated animals. Serum fibrinogen and fibrin split products were unchanged in both groups, indicating the absence of systemic fibrinolysis. There were no intracerebral hemorrhages. It is concluded that, in this rat model, TPA increases blood flow with subsequent improvement in the EEG recording after thromboembolic stroke without evidence of systemic fibrinolysis. Intravenous TPA may be useful in the treatment of acute stroke in man.

Animals↗
PubMed1985

Ipsilateral sensory symptoms caused by a temporal lobe glioma.

Sensory symptoms can occasionally occur ipsilateral to lesions of the insula. We report a patient with left-sided sensory symptoms preceding the diagnosis of a left temporal lobe glioma. The anatomical basis for this clinical phenomenon is reviewed. This patient illustrates the complex neuroanatomical pathways and the clinical correlations from lesions in this region.

Brain Neoplasms↗