Angelo A. Patil

Transoral stereotactic biopsy of the second cervical vertebral body: case report with technical note

Although the transoral approach to the atlantoaxial region is generally an open surgical procedure, in patients in whom only tissue diagnosis is required, a needle biopsy can be done. In this paper a patient with a metastatic lesion in the second cervical vertebral body is presented, and the technique for needle biopsy of the second cervical body using stereotactic methods is described.

The value of intraoperative scans during CT-guided stereotactic procedures

SumamryThe accuracy stereotactic procedures performed during the pre-computed tomography (CT) era was confirmed by intraoperative X-ray pictures. With the availability of CT it is now possible to confirm the position of the probe-tip on an image of the target. For biopsy of small lesions in critical areas of the brain, permanent placement of radioactive seeds, or thalamotomy, it would be desirable to have confirmation of the site of the probetip prior to performing the main step of the procedure. Intraoperative CT was performed in 216 stereotactic procedures carried out on the scanner table including biopsies, aspiration of cysts, brachytherapy, aspiration of abscesses, thalamotomy, and evacuation of intracerebral hematoma. In 6 cases, inaccuracies were detected, which it was possible to correct so as to place the probe where desired.

Role of brachytherapy in the management of the skull base meningioma. Treatment of skull base meningiomas.

Background. The treatment of primary and recurrent skull base meningiomas presents a formidable surgical problem.

Free-standing, stereotactic, microsurgical retraction technique in “key hole” intracranial procedures

SummaryFree-standing, stereotactic, microsurgical retraction technique involves integration of a standard image-guided stereotaxis, an operating microscope and free-standing micro-retractors, data acquisition from computed tomography (CT) images, trajectory determination, and obtaining tumor configuration “in line” with the trajectory using standard CT computer program. The free-standing stereotactic micro-retractors are directed to the lesion using the stereotactic frame. The remainder of the procedure is carried out independent of the stereotactic frame. The technique allows unobstructed access to deep lesions through a “key-hole” opening with excellent visualization of the lesions, and accurate retractor placement. Independent retractor movement also allows visualization of the different corners of the wound. Experience with the first 15 consecutive procedures for stereotactic excision of deep lesions using the Patil frame is reported. Based on this preliminary experience, this technique is free of obstruction, accurate and safe.

Permanent high-activity iodine-125 in the management of petroclival meningiomas: case reports.

Two cases of petroclival meningiomas are reported wherein the tumors were completely destroyed without surgical resection or external-beam irradiation by means of permanent stereotactic implantation of one or two high-activity iodine-125 seeds.

Properties of electromagnetic field focusing probe

The electromagnetic field focusing (EFF) apparatus consists of a radio fre quency generator, solenoidal coil, and a hand-held or catheter probe. Applica tions such as aneurysm treatment, angioplasty, and neurosurgery in various models have been reported. The probe is operated in the near field (within one wavelength of an electromagnetic field source) of a coil inducing eddy currents in biological tissues, producing maximal convergence of the induced current at the probe tip. The probe produces very high temperatures depending on the wattage se lected for the given radio frequency of output power. The high temperature can be used in cutting, cauterizing, or vaporizing. The EFF probe is comparable to different types of lasers and to bipolar and mono polar cautery. The EFF probe can be used with catheters or endoscopes. Objec tives of this study were to determine what the thermal properties of the EFF probe are and how instrument parameters can be varied to obtain different temperatures in the tissue near the probe tip. In this study an F2 catheter was used as an insulated sheath and the tip of the guide wire was used as the probe tip. Different powers, wave forms, coil-to- probe distances, and probe-tip lengths were tested on a phantom that simulates tissue electrical properties. Some of the experiments were conducted under nor mal saline to simulate treatment of tissue with body fluids such as blood vessels or brain tissue under normal physiologic conditions. It is concluded that the EFF probe has the advantages of easy manipulation, relative safety, cost effectiveness, and a high degree of spatial control. Only at the point of contact do extremely high temperatures occur. Small volumes of heat dissipation occur around the tip, especially when the sinusoidal wave form is used. Temperatures delivered are related to power applied, coil-to-probe-tip distance, and probe-tip length.

Modifications of transnasal and transoral stereotactic procedures — Technical notes

SummaryStereotactic transnasal and and transoral procedures have been reported by different authors in the past. In this paper, several modifications of these methods are described. The modifications are: transnasal approach to the frontal skull base and suprasellar regions; and transoral approaches to the clivus, the petroclival junction, medial part of the cerebellopontine angle and the lateral mass of C-1. Eleven patients were operated on using these modifications. The procedures were for biopsy and brachytherapy. No complications resulted from the procedures.

Electromagnetic Field Focusing Probe (EFFP) — A New Angioplasty Tool:

An electromagnetic field focusing probe (EFFP) consists of a radiofrequency generator, solenoidal coil, and a hand-held or catheter probe. The probe is oper ated in the near field (distance within one wave length of an electromagnetic field source) of a coil, which induces eddy current in a biological tissue. The induced eddy current is converged maximally at the tip of the probe upon con tact of the tip with the tissue. The probe produces very high temperatures de pending on the wattage selected. In this study, the EFFP was used to evaporate atheromatous plaques in hu man cadaver abdominal aorta specimens, which were then studied histologi cally. Gas produced by this technique was analyzed and the volume found to be related to power delivered, but in such small amounts as to be of no embolic significance. While temperature varied with wattage and time of application, it was maximal at the probe tip and easily controlled, resulting in clean oblitera tion of plaque.

Electromagnetic field focusing (EFF) probe for intravascular endarterectomy. Preliminary feasibility study.

SummaryVaporization of atheromas in 10 human aorta segments immersed under flowing blood in vitro were done using the EFF probe. No increase in packed cells of the flowing blood following atheroma vaporization were noted suggesting absence of post vaporization debris. No damage to the aorta underlying the vaporized atheroma was noted on light microscopy suggesting well localized vaporization process. This study suggests that EFF probe might be a safe tool for intravascular endarterectomy.

Axial herniation with brain stem deformity as a cause of sleep apnea

A patient with an intracerebral hematoma and associated edema in the high right hemisphere parasagittal convexity had several episodes of apnea at night and during the day when she was asleep. On computed tomography (CT) scan, the hematoma demonstrated no evidence of brainstem compression. Sagittal magnetic resonance image (MRI), revealed the hematoma and edema mass resulted in central herniation with axial deformity of the brainstem. This is believed to be the cause of the apneic episodes. Treatment with mannitol and steroids promptly relieved the symptom.