Rosa Urciuoli

Photocoagulation of Cerebral Arteriovenous Malformations and Arterial Aneurysms with the Neodymium: Yttrium-Aluminum-Garnet or Argon Laser: Preliminary Results in Twelve Patients

Six arteriovenous malformations (AVMs) and five arterial aneurysms (AAs) were treated with either argon or neodymium:yttrium-aluminum-garnet laser irradiation; one AVM was treated with both. All AVMs were occluded completely, leaving adjacent tissue untouched and preserving the regional vascularization. Photocoagulation produced varying effects on AAs: in one case an intraoperative rupture was sealed, in two cases the volume of an ectasia was reduced when the bleeding and thinner areas were coagulated, and in one case a saccular aneurysm was progressively and completely obliterated while the patency of the parent artery was preserved. These preliminary results are satisfactory; more experience will indicate how and when these new techniques can replace traditional ones or be used in combination with them.

The effects of new technologies on the surgical management of brainstem tumors.

Nuclear magnetic resonance, real-time and A-scan ultrasonography, and computerized CO2 lasers were recently introduced for diagnosis and surgical treatment of brainstem tumors. These new technologies offer many advantages: safe but aggressive surgery on the brainstem, the possibility of performing a correct histologic diagnosis, and an exact indication for radiotherapy. Eleven tumors were operated on in our series: seven were intrinsic and four protruded out from the axis. Patients with high-grade malignant tumors died from 5 to 12 months after treatment, whereas those with pilocytic astrocytoma are still alive and leading useful lives.

Rat brain metabolism enzyme activity variations following He−Ne laser irradiation

In order to gain insight into the metabolic modifications induced in rat brain tissues by helium-neon (He-Ne) laser irradiation, in the research described here, we investigated the variations in the activity of the enzymes aspartate transferase (AST, EC 2.6.1.4), both cytosolic and mitochondrial, glutamate dehydrogenase (GIDH, EC 1.4.1.3), and total superoxide dismutase (SOD, EC 1.15.1.1), in the brain of rats treated with a very small dose (1.08 J) of He-Ne laser radiation. The rats were sacrificed 4 h after the treatment. The enzymes were evaluated spectrophotometrically in brain extracts of irradiated animals and also in untreated rats (controls) and rats that underwent simulated treatment (stressed). The data obtained from 5-10 animals assayed individually showed that, in the in toto brain tissues of the irradiated rats compared to the stressed rats, there was a marked increase of total SOD, together with an appreciable decrease of cytosolic AST, and insignificant variations in mitochondrial AST and GIDH. Stress alone caused a considerable decrease of total SOD and small but statistically significant increases of s-AST, m-AST, and GIDH.

Effect of in vivo HeNe laser irradiation on biogenic amine levels in rat brain

In order to elucidate the metabolic modifications induced in rat brain by low power He-Ne laser irradiation in vivo, the variations in the biogenic amine levels in cortex, striatum and hippocampus were studied. Noradrenaline (NA), dopamine (DA) and serotonin (5-HT) were evaluated by HPLC-EC on irradiated rats, untreated rats (controls) and rats which had undergone restraint stress (stressed). The results obtained on groups of four to eight rats assayed individually showed that irradiation caused a strong increase in 5-HT in striatum and hippocampus, a small but significant decrease in NA in cortex, and DA levels were not significantly affected. Restraint stress per se led to a considerable decrease in 5-HT and DA in striatum and hippocampus, but did not significantly alter the NA levels.

New technologies in neurosurgery: Effects on the conventional techniques and anaesthesiological considerations

New technologies have been recently introduced into neurosurgery: laser sources, ultrasonic aspiration, intraoperative echotomography and intraoperative Doppler flowmeter. The aim of this work, showing the use of these instruments in different neurosurgical operations, is to discuss the effective improvements of the surgical techniques when comparing new and traditional technologies. The laser is able to concentrate high energies in restricted areas allowing a maximum selectivity. Having a superficial destructive effect with associated hemostasis, CO2 and argon are suitable in dissection maneuvers. Nd:YAG produces a high thermal diffusion, consenting a deeper and extended tissue removal and a considerable reduction of intraoperative blood loss also in vascularized tumors. A promising field of application of the laser is the treatment of cerebral vascular malformations. In arterio-venous malformations the irradiation of the nidus with Nd:YAG produces a rapid obliteration of the pathologic vessels. This technique avoids the isolation of the feeding arteries and reduces the manipulation of the surrounding tissue. In small saccular aneurysms an argon laser is used to produce a shrinkage of the dilatation with consequent occlusion of the malformation. The ultrasonic aspirator is used in the tumoral surgery to obtain a more rapid demolition of the mass by fragmentation and suction. Intraoperative echotomography consents a sharp topographic localization of the lesion, particularly in deeper cerebral areas, providing data on the nature of solid tumors. The intraoperative Doppler flowmeter is useful for identification of the feeding arteries and the shunt of the small deep-seated arterio-venous malformations consenting a dynamic evaluation of the operation. General anaesthesia in neurosurgical procedures is favourably influenced by laser use. Conventional anaesthetic techniques, however, must be modified to avoid the harmful effect of the laser, depending on the movements of the brain surface, which may switch the laser beam to adjacent tissues, and become particularly dangerous when the laser is used near high functional structures or when the laser is driven by a computer.

Sudden presentation of intracranial meningioma after elective general anesthesia.

A case of “silent” intracranial meningioma unmasked by narcosis is described. The diagnosis was made because of the patients failure to wake up after elective general anesthesia for orthopaedic surgery. Factors leading to this complication and its management are discussed. Early computed tomography scan and antiedema therapy are strongly suggested for these patients.

Laser Doppler flowmetry in neurosurgery

&NA; Laser‐Doppler flowmetry (LDF) provides a reliable measurement of local cerebral blood flow (ICBF) as demonstrated by multiple validation studies. This article evaluates the clinical applications of LDF in neurosurgery. With the availability of modified probes, it is possible to carry out LDF monitoring of neurosurgical patients in the intensive care unit. Currently, there are multiple systemic and intracranial parameters that are interactive and separately monitored. A multichanneled digital data acquisition system allows these data to be compiled in a single computer environment for the interpretation of ICBF changes. Guidelines are suggested for the clinical use of LDF monitoring, and the technical features of monitoring including the interpretation of data are summarized.

First Experience with a Laser Clamp in Neurosurgery

The laser clamp described in this paper was invented by the senior Author (V. A. F.) and was designed and built by one of the authors (W. C).

Laser Doppler Flow Measurement for the Evaluation of Cerebral Microcirculation

The intraoperative assessment of cerebral blood flow (CBF) variations would be of the utmost value to the neurosurgeon. Intraoperative monitor ing of CBF is directed to identify either the impairment of hemodynamic regulating mechanisms (autoregulation, vasoreactivity) produced by a lesion [SAH (sub aracnoidal hemorrhagy), tumor, trauma] or the modifications of local perfusion produced by surgical maneuvers. The ideal intraoperative device would not be invasive and cumbersome; moreover, it would not alter regional CBF during the detection procedures, allowing real time continuous monitoring of CBF; and the operation would not be prolonged by the flow measurement. The laser Doppler (LD) flowmeter has been extensively used to study microcirculation in various tissues.

Intraoperative laser Doppler flowmetry of cerebral microcirculation

Several techniques have been utilized for intraoperative monitoring of regional cerebral blood flow (rCBF):Xenon-l33 injection technique,therma diffusion flowmetry and Laser Doppler. The results obtained intraoperatively by Laser Doppler flowmeter on 145 patients are analysed and discussed.