Percussion chisel.

A new percussion chisel exclusively designed for neurosurgical use is presented that can be applied easily and safely. It is particularly useful in the removal of bony membranes through a transsphenoidal approach.

Epipteric bones in the pterion may be a surgical pitfall.

BACKGROUND: The pterion, the most commonly used neurosurgical landmark, is defined as the junction of frontal, parietal, and greater wing of the sphenoid and the squamous part of temporal bones. Our aim was to identify the variations of the pterion which may be a potential surgical pitfall. METHODS: Both sides of 300 adult skulls were examined but 110 sides were eliminated since their pterion could not be identified owing to a damage. The shortest distance between the lateral orbital rim and the most anterior junction of the four bones forming the pterion was measured on all sides. RESULTS: Out of 490 sides the pterion was found to contain epipteric bones in 44 (9 %), and in these skulls the most anterior junction of the bones may be as close as 16 mm to the lateral orbital rim. CONCLUSION: In skulls with an epipteric bone variation, particularly the anterius and proprium types; the pterion can mistakenly be assessed to be at the most anterior junction of bones and a burr hole placed over there may cause inadvertent penetration into the orbit.

No effect of 50 Hz magnetic field observed in a pilot study on pentylenetetrazol-induced seizures and mortality in mice.

This study was planned so as to evaluate whether magnetic field exposure has any significant effect on the pentylenetetrazol (PTZ)-induced seizures. Mice were exposed to 50 Hz, 2 G (0.2 mT) magnetic field in glass cages for 1 h. Sham exposure was produced by turning off the current while the animals were in the same exposure volume. Then, PTZ was administered intraperitoneally (i.p.) at a dose of 60 mg/kg and the animals were observed for 30 min. Subsequently, the latency to seizure onset, total seizure duration, the number of seizure episodes and mortality were recorded for each subject. There was no evidence for a significant effect of the 50 Hz magnetic field on the mean number of PTZ induced seizures, seizure latency, total seizure duration and mortality (P>0.05). As a conclusion the present study failed to provide any further support for a therapeutic potential of magnetic field.

Does thromboxane A2 synthase inhibitor UK-38485 prevent the vasoconstrictor effects of endothelin-1 on rabbit basilar artery?

Prevention of the production of thromboxane A2--a potent vasoconstrictor and aggregating metabolite of arachidonic acid--or infusion of the stable analogues of prostacyclin--which is another cyclo-oxygenase metabolite of arachidonic acid--has been shown to be beneficial in cerebral vasoconstriction. Endothelin-1, a peptide derived from endothelial cells, has been shown to induce a long-lasting cerebral vasoconstriction both in vivo and in vitro. The purpose of this study was to investigate the role of a novel thromboxane A2-synthase inhibitor UK 38485 on the acute vascular and morphological effects of Endothelin-1 applied intra-arterially on rabbit basilar arteries. The inguinal region of twenty four anaesthetized albino rabbits of both sexes were dissected and a catheter was inserted into the aorta via the femoral artery, for control angiography of the basilar artery and intra-arterial injection of ET-1 (0.25 ng total dose) and UK 38485 at a dose of 0.05 microgram kg-1 min-1 for 20 min or saline. Angiographic vasoconstriction quantification and morphological investigations of both vessels and brain stem either by light microscopy or transmission electron microscopy were the techniques applied for the study. We found out that, although the systemic administration of UK 38485 resulted in a potent antagonism of the acute vasoconstriction as visualized in angiographic studies, it did not affect the morphological changes induced by Endothelin-1 on the vessel wall. The results indicated that there might have been an interaction between Endothelin-1 and the prostaglandin synthesis mechanism in acute cerebral vasoconstriction.

Assessment of mortality associated with mild head injury in the pediatric age group.

Reducing mortality among accident and trauma patients requires careful attention to monitoring those regarded as being at low risk. We hospitalized almost 1600 head-injured patients in the period between 1979 and 1992 at the Neurosurgery Department of Gazi University Medical School, Ankara, Turkey. These patients were selected from among the numerous patients admitted to our emergency unit and treated with the same protocol in the same department. Among the hospitalized children, there were three patients defined as having a mild head injury on the basis of Glasgow Coma Scale scores of 15 who later had unfavorable outcomes. Clinical signs that might identify potentially endangered patients with mild injury were gathered; these included the presence of post-traumatic amnesia, somnolence, irritability, anisocoria, local evidence of trauma to the head, associated injuries, history of altered consciousness, and skull fracture. The study was designed to identify features by which patients who are in real danger can be distinguished among the many with trivial trauma that we face every day. We did not find any identifying clinical features and concluded that computed tomographic scanning is the only reliable answer. This will reduce avoidable mortality and morbidity by identifying the patients who are at higher risk than is at first evident.

Immediate ultrastructural effects of endothelin-1 on rabbit basilar artery. A comparison between immersion and perfusion fixation techniques.

In this study intra-arterial Endothelin-1 was applied to rabbit basilar arteries and morphological findings were compared between two groups who were either perfusion fixed or immersion fixed. We planned to establish the quantitative dimension of the drug-induced morphological alterations, independent of the fixation technique's effect. There was an abundance of collagenous fibres deposited among the smooth muscle cells which was not observed in control arteries and after immersion fixation. These degenerative changes are similar to the finding following subarachnoid haemorrhage. The only fixation-related difference was the fact that lamina elastica interna was not corrugated in the perfusion fixation group. It is concluded that, the observed changes in the connective tissue of the arterial wall alter the passive elastic properties and so affect the degree of the response to the vasoactive messengers.

Computed tomographic ventriculography: a clinicoradiological study of 31 cases.

We present 31 patients whose diagnoses were established by the aid of computed tomographic ventriculography. The indications for and diagnostic value of this method are reviewed.

Alteration by Iloprost of the vasospastic effects of endothelin-1 in rabbit cerebral vessels.

The reversal of endothelin-1 induced cerebral vasospasm with Iloprost was studied in the rabbit. Vasospasm in the basilar artery was evaluated by angiography; cerebral ischaemia by 'red-neurone-count' on light microscopy and morphological changes by electron microscopy. A potent antagonistic effect of Iloprost against ET-1 was observed in each of the parameters measured.

Computer assisted quantification of vasospasm on angiograms.

We describe a new computer-based, automated method for the assessment of in vivo cerebral vasospasm. Arterial diameter measurements were performed on post-processed digital substraction angiographic images, using "pixel" as the unit. Vasospasm which was difficult to detect by visual inspection could be measured by the "stenosis quantification" program. A computer-assisted method such as we describe might decrease the risk of subjective errors.

Tuberculoma in the suprasellar cistern: possible CT--misinterpretation as aneurysm.

A patient with multiple intracranial tuberculomas mimicking aneurysms is reported. The diagnosis was established by CT during the treatment of tuberculous meningitis. Anti-tuberculous therapy was continued until the radiological resolution of the lesions. A discussion of previous reports on the non-operative treatment of intracranial tuberculomas is included.