Phenytoin toxicity with mandibular tremor secondary to intravenous administration.

The parenteral form of phenytoin is the most commonly used antiepileptic agent during the perioperative period in neurosurgery clinics. We report observations in a 52-year-old male patient with hypoalbuminemia and phenytoin intoxicity following 1 day preoperative administration and a 7-day postoperative intravenous administration of the drug with no modification of the oral dose. This report emphasizes the need for careful surveillance of phenytoin-induced toxicity during parenteral therapy, especially in debilitated patients.

Distal middle cerebral artery aneurysms. Endovascular treatment results with literature review.

SUMMARY: Intracranial aneurysms of the distal intracranial arteries are uncommon lesions which are difficult to treat with surgical techniques. Distal middle cerebral artery (MCA) aneurysms constitute approximately 5% of all MCA aneurysms.We report the results of our coil embolization for the treatment of distal MCA aneurysms. Eleven patients (four men and seven women, average age 37 years) with distally located MCA aneurysms were treated. Four of the aneurysms were fusiform in shape and the remainder were saccular. Seven of the aneurysms were in the dominant hemisphere. Four of the seven patients who had saccular aneurysms were treated with selective aneurysm embolization. The remaining seven patients were treated with aneurysmal sac and parent artery coiling. All patients had good retrograde flow into the peripheral branches of the occluded artery. All the procedures were completed successfully without any additional neurological deficits. Coil embolization is a safe and effective technique for the treatment of distal MCA aneurysms. If the parent artery cannot be preserved, pial collaterals can supply adequate blood to prevent neurological deficits.

Cervical neural foraminal widening caused by the tortuous vertebral artery.

A case of cervical neural foraminal widening due to tortuous vertebral artery is presented. This entity is rarely seen. Plain radiography, CT, 3-D CT angiography, MRI, and MRA findings of the case are presented and the importance of this vascular anomaly in the differential diagnosis of neural foraminal widening is discussed.

Identification of a bioactive domain in the amino-terminus of glucose-dependent insulinotropic polypeptide (GIP).

The incretins are a class of hormones released from the small bowel that act on the endocrine pancreas to potentiate insulin secretion in a glucose-dependent manner. Due to the requirement for an elevated glucose concentration for activity, the incretins, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1, have potential in the treatment of non-insulin-dependent diabetes mellitus. A series of synthetic peptide GIP fragments was generated for the purpose of elucidating the bioactive domain of the molecule. Peptides were screened for stimulation of cyclic AMP (cAMP) accumulation in Chinese hamster ovary cells transfected with the rat islet GIP receptor. Of the GIP fragments tested, GIP(1-14) and GIP(19-30) demonstrated the greatest cAMP-stimulating ability over the range of concentrations tested (up to 20 microM). In contrast, GIP fragments corresponding to amino acids 15-42, 15-30, 16-30 and 17-30 all demonstrated weak antagonism of GIP(1-42) activity. Competitive-binding displacement studies indicated that these peptides were low-affinity ligands for the GIP receptor. To examine biological activity in vivo, a bioassay was developed in the anesthetized rat. Intravenous infusion of GIP(1-42) (1 pmol/min/100 g) with a concurrent intraperitoneal glucose load (1 g/kg) significantly reduced circulating blood glucose excursions through stimulation of insulin release. Higher doses of GIP(1-14) and GIP(19-30) (100 pmol/min/100 g) also reduced blood glucose excursions.

Defective glucose-dependent insulinotropic polypeptide receptor expression in diabetic fatty Zucker rats.

Glucose-dependent insulinotropic polypeptide (GIP) is a peptide hormone that is released postprandially from the small intestine and acts in concert with glucagon-like peptide (GLP)-1 to potentiate glucose-induced insulin secretion from the pancreatic beta-cell. In type 2 diabetes, there is a decreased responsiveness of the pancreas to GIP; however, the insulin response to GLP-1 remains intact. The literature suggests that the ineffectiveness of GIP in type 2 diabetes may be a result of chronic homologous desensitization of the GIP receptor. Yet, there has been no conclusive evidence suggesting that GIP levels are elevated in diabetes. The hypothesis of the present study is that one cause of decreased responsiveness to GIP in type 2 diabetes is an inappropriate expression of the GIP receptor in the pancreatic islet. This hypothesis was tested using a strain of diabetic fatty Zucker rats. The obese rats displayed basal GIP levels similar to the control animals; however, they were unresponsive to a GIP infusion (4 pmol.min(-1). kg(-1)), whereas the lean animals displayed a significant reduction in blood glucose (GIP levels, 50% control after 60 min, P < 0.05) as well as a significant increase in circulating insulin. GIP also potently stimulated first-phase insulin secretion from isolated perifused islets (10.3 +/- 3.0 x basal), and GIP and GLP-1 potentiated insulin secretion from the perfused pancreas (6 x control area under the curve [AUC]) from lean animals. GIP yielded no significant effect in the Vancouver diabetic fatty Zucker (VDF) rat pancreases, whereas GLP-1 elicited an eightfold increase of insulin secretion from the perfused VDF pancreas. Islets from lean animals subjected to static incubations with GIP showed a 2.2-fold increase in cAMP, whereas GIP failed to increase islet cAMP in the VDF islets. Finally, the expression of both GIP receptor mRNA and protein was decreased in islets from VDF rats. These data suggest that the decreased effectiveness of GIP in the VDF rat and in type 2 diabetes may be a result of a decreased receptor expression in the islet.

A rare cause of hyperprolactinemia: persistent trigeminal artery with stalk-section effect.

The primitive trigeminal, otic, hypoglossal, and proatlantal intersegmental arteries are fetal anastomoses between the carotid and vertebrobasilar systems. Persistent trigeminal artery (PTA) is the most frequent embryonic communication between the vertebrobasilar and carotid systems in adults. We report a case of PTA compressing the left side of the pituitary gland and stalk, in a patient with elevated blood prolactin level.

Cervical spinal cord intramedullary abscess. Case report.

A case of progressive symptoms and signs of cervical spinal cord damage due to intramedullary abscess is reported. The literature is reviewed and the radiological features, particularly magnetic resonance image, are analyzed.

Middle cerebral artery duplication associated with multiple intracranial aneurysms. Case report.

We present a case of middle cerebral artery (MCA) duplication associated with ipsilateral distal MCA and contralateral MCA bifurcation aneurysms.

Neonatal intracranial hemorrhage due to rupture of arteriovenous malformation.

Two cases of neonatal intracerebral hemorrhage secondary to rupture of arteriovenous malformation are reported and the pertinent literature is reviewed. Despite the limited number of cases, review of the literature and our results demonstrate that the outcome of surgical removal of an arteriovenous malformation in the neonatal period is not as poor as was previously believed.

The principles of surgical management in dumbbell tumors.

OBJECTIVE: Tumors located in posterior mediastinum that extends into spinal canal via intervertebral foramen are called as Dumb-bell or Sand-glass tumors. Most of these tumors are neurogenic in origin but sometimes other rare tumors can also form in this shape. Herein three neurogenic tumors of the mediastinum that extended into the spinal canal are presented METHODS: In all patients that have been operated in our clinic during 1992-1993, we preferred one-stage removal described by Akwari that consists of posterior laminectomy by neurosurgical team to free the tumor within the spinal cord followed by a posterolateral thoracotomy and excision of the tumor by thoracic surgeons in the same setting. RESULTS: All three patients are alive and free of symptoms after 23, 16 and 13 months respectively. According to the pathological examinations of the specimens in the three patients, the exact diagnosis were reported as neurofibroma, paraganglioma and pheochromocytoma respectively. CONCLUSIONS: In recent reports, a combined surgical approach is recommended for dumb-bell neurogenic tumors in posterior mediastinum. We also recommend a combined and one stage removal of dumb-bell neurogenic tumors if possible. A team-work of thoracic and neurosurgeons will minimize the morbidity and mortality after the surgical procedure, as well as giving the opportunity to remove the tumor totally in one session.

Transcranial Doppler assessment of cerebral blood flow velocity in term newborns.

Using the transcranial Doppler technique to assess postnatal changes in cerebral blood flow velocity, we studied the anterior cerebral artery, middle cerebral artery, and internal carotid artery of 31 healthy, term newborn infants. Normative values for the 1st, 3rd, and 5th days of life were determined. Cerebral blood flow velocity values in all three arteries examined correlated well with each other and we observed a statistically significant increase only in middle cerebral artery blood flow velocity between the 1st and 3rd, and 1st and 5th postnatal days. Thus, if we assume that flow velocities in various cerebral arteries undergo similar change, only one representative artery need be examined. The middle cerebral artery appears to be the vessel of choice. This choice simplifies the recording procedure, particularly in repeated examinations.

Extraspinal ependymoma presenting as a subcutaneous mass posterior to the sacrococcygeal region. Case report.

Ependymal cells may be found within the coccygeal ligament as well as in heterotopic positions and therefore ependymomas may rarely occur in extraspinal locations. Although the cauda equina is the most common location, less than 5% of all spinal ependymomas occur extradurally in the sacrococcygeal region. We report a case of extraspinal myxopapillary ependymoma arising in the subcutaneous soft tissue posterior to the sacrococcygeal region and review the relevant literature.

Examination of autologous and embryonic cortical brain tissue transplantation to adult brain cortex in rats.

Autologous and embryonic cortical brain tissue was transplanted to adult rats in order to reconstruct experimentally degenerated cortical brain tissue. Rats were decapitated within 6 or 12 weeks. Viability of the graft tissues was studied by light and electron microscopy. Embryonic cortical brain tissue grafts became enlarged but adult cortical brain tissue grafts were found to be unaltered. Electron-microscopically observed mitochondria and other cell organellae and the newly vascularized areas clearly showed that the graft tissues were alive.