Lasers In Neurosurgery Research Articles

BOOK REVIEWS: Lasers in Neurosurgery. (Lasers in Medicine and Surgery Series 3).

BOOK REVIEWS: Lasers in Neurosurgery. (Lasers in Medicine and Surgery Series 3).

Lasers in Neurosurgery

Lasers in Neurosurgery

Continuous intraoperative monitoring of brain stem evoked potentials in laser neurosurgery : L.H. Mattos Pimenta and F.J.C. Lucas (Albert Einstein Hospital, São Paulo, Brazil)

Continuous intraoperative monitoring of brain stem evoked potentials in laser neurosurgery : L.H. Mattos Pimenta and F.J.C. Lucas (Albert Einstein Hospital, São Paulo, Brazil)

Neurosurgical lasers for tumour removal

The early 1970s saw the birth of microscopic neurosurgery and the late 1970s the birth of laser neurosurgery. For more than 10 years now, laser radiations have been used during neurosurgical procedures: mostly for tumoral removal concerning essentially benign lesions. The reference laser has been and still is the CO2 laser, which has a limited penetration into CNS tissues. Until recently the Nd-YAG laser was used with its normal spectral transition, 1.064 μm. Because of its important diffusion in the CNS, it cannot be widely used except for shrinking large vascularized tumours such as meningiomas. The technological evolution has brought the laser specialists—physicists, medical doctors and surgeons—new concepts and new wavelengths which will progressively broaden laser applications and surgical procedures towards greater effectiveness, security and simplification. Holmium-YAG (2.1 μm), Erbium-YAG (2.9 μm) or long Nd-YAG wavelengths (1.44 or 1.32 μm) have been studied by different teams. The 1.32 μm Nd-YAG transition has been clinically used for about 2 years by a few neurosurgical teams (Beck in Munich, Roux in Paris, and more recently Lombard and Fasano in Torino, Ascher in Gratz). Laser radiations can be useful essentially during the removal of benign tumours, mostly if they are well vascularized and placed near functional structures such as the brain stem, the cranial nerves, the spinal cord: the CO2 laser is most efficient for vaporization; 1.06 Nd-YAG is effective for coagulation; 1.32 Nd-YAG provides very satisfactory photoevaporation effects if used with a superpulsed emission, and/or with a focusing handpiece, it also has good haemostatic properties with a c.w. output. The development of new optic fibre conducted wavelengths appears to be a possible answer to new requisites which should lead to the development of endoscopic neurosurgery (intraventricular tumours, discal herniations) and sterotaxic laser surgery (deep-seated intra-cerebral lesions).

Lasers in Neurosurgery

Lasers in Neurosurgery

Application of Lasers in Neurosurgery

Application of Lasers in Neurosurgery

Lasers in Neurosurgery: Rare Now, but Exciting Applications Under Study PDT, Nerve Welding, Excimer Use Being Explored

<b>Lasers in Neurosurgery: Rare Now, but Exciting Applications Under Study</b> PDT, Nerve Welding, Excimer Use Being Explored

Optical properties of human brain tissue, meninges, and brain tumors in the spectral range of 200 to 900 nm.

Considering the increasing use of lasers in neurosurgery and the increasing number of wavelengths of laser light becoming available, we evaluated optical properties between 200 and 900 nm of meninges, normal human brain tissue, and brain tumors. We used a two-beam spectral photometer with an integrating sphere as the measuring instrument. The material consisted of 13 brains and 1 specimen each of dura mater, falx, and arachnoid obtained at autopsy and 30 samples of brain tumors removed during operation. In tissue samples more than 5 mm thick, the relative levels of absorption and scattering were estimated from the relative level of reflection measured according to the Kubelka-Munk theory. In thin tissue slices, penetration depth was calculated according to Beer's law from measurements of reflection and transmission. Generally, in all tissues there was an increase of reflection, scattering, and penetration depth and a decrease of absorption from the ultraviolet up to the near infrared spectral range interrupted by the absorption bands of hemoglobin. Within the ultraviolet spectral range, no major differences of optical properties were observed. Within the visible and near infrared spectral range, white matter reflected most of the incident power and showed the lowest level of absorption and the shortest penetration depth. Low grade gliomas revealed optical properties similar to those of gray matter. In comparison with normal brain tissue, meningiomas and glioblastomas showed significantly higher levels of absorption calculated according to the Kubelka-Munk theory from reflection measurements in thick tissue samples, but also deeper penetration obtained from measurements of reflection and transmission in thin slices, especially within the near infrared spectral range.

Direct surgical attack on pontine and rhombencephalic lesions.

The introduction of lasers in neurosurgery in 1976 can be considered as a major contribution to gaining access to "untouchable" areas of the brain. This immaterial instrument provides for precise cutting at low penetration depth in surrounding tissues and may carbonize, and thus remove, layers not to be touched because of their highly sensitive vicinity. From a total of 794 patients experiencing the advantages of laser surgery (1976-1984), a series of 12 children with lower brainstem tumors is presented. Intraoperative instability of vital functions was absent throughout, leaving the patients without deterioration of their initial neurological condition. Given appropriate handling and adequate experience, the laser is a singularly helpful surgical tool for gaining access to areas hitherto barred to surgery.

Laser neurosurgery: Past, present, and future

The incorporation of the laser into the neurosurgical armamentarium was surprisingly late in comparison to its use in other precise fields, such as ophthalmology and otolaryngology. Since its arrival, however, a veritable revolution in neurological surgery has taken place. The uses of this instrument, present and future, are discussed in their historical perspective. The author proposes an ideal laser for neurosurgery.

Present status of laser neurosurgery.

A three-fold approach to the status of laser neurosurgery was taken: 1) Questionnaire to Program Directors for neurosurgery training in the United States and Canada; 2) an analysis of titles in the preliminary neurosurgery program of the Fifth International Congress of Neurosurgery; 3) A literature survey covering the last 3 years of publication. The results showed increasing interest in the use of lasers in neurosurgery, especially for neoplasms in brain and spinal canal. The CO2 laser still dominates the field but Neodymium YAG is also finding wide use. The author comments on directions that laser neurosurgery may take in the future. Special emphasis is made on new applications combining advanced technologies, including CAT scanning, ultrasonography, stereotaxic techniques, and computer control.

Using lasers in neurosurgery

Surgical lasers have definite limitations. They are best at removing small tumors in delicate brain locations. They are useful for extrinsic lesions and have been found to be helpful in pediatric neurosurgery. They are not useful for many intrinsic hemisphere tumors, especially glioblastoma. The laser does not make a surgeon better; it may, however, allow the surgeon to dissect the tumors in a more delicate and precise way.

Lasers in neurosurgery: a review.

In recent years neurosurgeons have shown an increasing interest in lasers. An understanding of the basic laser mechanism and tissue effects is important. CO2 laser is an excellent no-touch tool for excising and evaporating brain tumors. It has several other uses in neurosurgery both with free-hand technique and with microscope attachment and a micromanipulator. It is easier and more precise to manipulate a laser beam than any of the conventional instruments. Nd:YAG and argon lasers are more effective for coagulation of blood vessels and for dealing with vascular neoplasms. Microvascular anastamosis has been achieved with the use of Nd:YAG laser in experimental animals and has potential for practical application in extra-intracranial bypass operations. There are many advantages and some disadvantages to the use of lasers in neurosurgery.

Anesthesiologic considerations in laser neurosurgery.

The laser has been welcomed to the neurosurgical armamentarium because of the inherent precision and gentleness of the no-touch technique. In order to maximize laser safety and efficacy, however, certain anesthesiologic considerations, specific to neurosurgery, must be realized. Motion of patient (target) during routine anesthesiologic checks or as the result of physiologic excursions during myocardial contraction and respiration must be minimized. Ventilatory parameters, anesthetic agents, and cardio active drugs are considered.