Roberto Maria Ponzio

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.

Treatment of cerebral arterio-venous malformations with laser.

The surgical application of the laser in the treatment of vascular diseases of the brain is based on its characteristic to perform an immediate or delayed modification of the vessel wall either by shrinking the collagenous fibres or by intraluminal thrombosis. Personal researches have been carried out to study the histological modifications of the vessel wall in normal arteries following laser irradiation with Nd:YAG. On this basis we have treated arterio-venous malformations (AVMs) in man. The laser enables radical surgery with a complete preservation of the healthy tissue surrounding the lesion because of reduced manipulation and the absence of intraoperative haemorrhage. Doppler technique and real-time ultrasonography are mostly suitable in the identification of the small deep-seated AVMs localizing the site of the malformation and the reactive glial tissue surrounding the lesion. The main indications are small AVMs located in critical areas of the brain.

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.

Preliminary Experiences with Argon and Nd: YAG Scalpel Laser in Neurosurgery

The possibility to approach a lesion performing a no-touch surgery is generally considered one of the main advantages of the laser. This property is expecially useful for the treatment of small deep-seated lesions (intraventricular, midline and brain stem tumors).

Preliminary observations on the use of the local thermochemotherapy in the treatment of malignant cerebral tumors

The use of local hyperthermia associated to chemotherapy for the treatment of malignant cerebral tumors is very recent.