Intraoperative calibration of the Patil stereotactic system during computed tomography (CT) guided stereotactic procedures--a technical note

A method for intraoperative calibration of the Patil stereotactic system is described. After adjusting the z and y coordinates, a marker is placed in the pivot block and a CT scan is obtained. The presence of the marker in the indicator block on the same horizontal line as the target, on the image of the target, would indicate that the y and z coordinates adjustments are accurate. After the arc is attached with the x coordinate adjusted, a CT scan is obtained with the arc vertical and the probe holder at zero angle (from the vertical) position. The presence of the middle of the probe holder in the same vertical line as the target would indicate accurate x coordinate adjustment. This technique, which can be applied also to other stereotactic systems, allows the surgeon to check not only the accuracy of the system but also the accuracy of the procedure prior to inserting the probe into the brain.

Intraventricular neurocytoma: a report of two cases

Intraventricular neurocytoma is a rare clinicopathological entity that has been recently recognized. Previous reports have not described the magnetic resonance imaging findings of this tumor. This paper describes two patients with neurocytoma in which serpiginous flow voids and isointensity with cortex were distinctive features on the magnetic resonance imaging scan. Immunohistochemical studies showed reactivity for neuron-specific enolase, Leu-7, and S-100 protein.

The effect of human chorionic gonadotropin (HCG) on restoration of physiological continuity of the spinal cord. A preliminary report

The effect of human chorionic gonadotropin (HCG) hormone on restoration of physiological continuity of the spinal cord in rats was studied. After complete transection of the spinal cord at the midthoracic level eleven of these 21 rats in the study received HCG for six weeks. The other ten served as controls. At the end of six weeks amplitude of the cortically evoked motor At the end of six weeks amplitude of the cortically evoked motor action potential (CEMAP) was measured. The amplitude of the motor action potentials was significantly greater (P less than 0.02) in HCG treated rats. The study thus shows that HCG might help in the restoration of spinal cord function.

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.

Survival of patients with glioblastoma multiforme treated by intraoperative high-activity cobalt 60 endocurietherapy

The authors report their initial treatment results in 49 patients with glioblastoma multiforme (GM) who received intraoperative endocurietherapy (ECT) with high-activity cobalt 60 (60Co) probe. Thirty poor prognosis (unresectable tumor) patients (Group I) with newly diagnosed GM were treated by either biopsy or subtotal excision, followed by 20.00-Gy single-fraction 60Co probe ECT, and 60.00-Gy external-beam radiation therapy (EXRT) (80.00 Gy total tumor dose). Nineteen patients (Group II) with recurrent, previously resected and externally irradiated GM were retreated with 20.00-Gy single-fraction 60Co probe ECT alone. The authors' initial experience with intraoperative ECT of GM is discussed.

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.

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 operated 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 contact of the tip with the tissue. The probe produces very high temperatures depending on the wattage selected. In this study, the EFFP was used to evaporate atheromatous plaques in human cadaver abdominal aorta specimens, which were then studied histologically. 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 obliteration of plaque.

Properties of electromagnetic field focusing probe

The electromagnetic field focusing (EFF) apparatus consists of a radio frequency generator, solenoidal coil, and a hand-held or catheter probe. Applications 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 selected 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 monopolar cautery. The EFF probe can be used with catheters or endoscopes. Objectives 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 normal 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Precision surgery with an electromagnetically induced current convergence probe application in aneurysm treatment, angioplasty, and brain tumor resection in in vivo and in vitro models

A hand-held probe, or one introduced through a catheter, rapidly produces an extremely high, tissue-vaporizing temperature in a precisely defined manner enabling surgeons or interventional radiologists to perform angioplasty, thrombose aneurysms, and vaporize tumors. The probe is operated in a near field of an inductive coil, and the current induced in the biologic tissue is converged maximally at the tip of the probe at the resonance frequency of both the inductor and the probe, producing a maximum temperature in excess of 1400 degrees C. Radio-frequency power controls the probe-tip temperature. The operation of the probe is comparable to that of a CO2 or YAG laser and is complementary to laser-surgical techniques. The low cost relative to lasers and simplicity of the device including its disposable components make the prospect of commercialization of this device promising.

Electromagnetic field focusing system in the treatment of brain tumors

The electromagnetic field focusing (EFF) probe, which is based on the principle of eddy current convergence, produces intense pinpoint heat at its point of contact with tissue. This allows cutting and vaporization of tissue and coagulation of vessels. The present experiments were conducted to study heat distribution to the surrounding tissue in brain and phantom and the effect on the brain of vaporization of intracerebral tumors in 19 rabbits. The follow-up period was as long as 47 days. The heating pattern showed a rise of temperature up to 250 degrees C at the probe tip, with minimal or no temperature increase at 2 mm and beyond. Minimal or no change was noted in the surrounding brain after tumor vaporization, indicating that this system would be safe in the vaporization of brain tumors in clinical neurosurgery.

Stereotactic excision of deep brain lesions using probe guided brain retractor

A probe guided brain retractor is described. The capability of it being guided by a probe allows it to be used for stereotactic excision of deep brain lesions. It can also be used with the ultrasound guided probe. Method of use with the stereotactic probe and early surgical experience is presented.

Electromagnetic field focusing (EFF) probe--a new neurosurgical tool

The electromagnetic field focusing (EFF) probe is capable of producing well circumscribed, intense heat at the point of contact with the tissue. Experimental studies were carried out to assess this probe as a neurosurgical tool using 38 rats and 4 mice with mammary carcinoma. The study on the rats included study of the cutting, coagulating and vaporizing effect on brain tissue including study of blood brain barrier disruption and heat dissipation. The study on the mice included the study of vaporizing property of the probe on solid tumours. The probe proved to be an excellent tool for cutting, coagulating and vaporizing purposes with very minimal disruption of blood brain barrier and demonstrated well circumscribed heating pattern. The study indicates that this tool combines the beneficial effect of both the YAG and CO2 laser.

Electromagnetically induced focused heat in the treatment of surgically created aneurysm models

A hand-held radiofrequency (rf) probe of a novel design based on the principle of the induced current convergence was used to treat aneurysm models using focused hyperthermia. Aneurysms were created surgically in rats by a side-to-side anastomosis between the inferior vena cava and the abdominal aorta or by grafting a donor abdominal aorta from one rat onto the abdominal aorta of another rat. Aneurysms were treated by inserting the 0.3-mm diameter probe tip into the fundus and applying the power for brief periods (0.5-1.5 sec) using a foot pedal. Collapse of the fundus was observed as the result of the heat-induced thrombosis. Thermal distribution in the immediate vicinity of the probe as well as the heating rate were measured in a uniformly dielectric phantom and in rat vessels. The aneurysms were histologically examined immediately, three days, and three weeks after the treatment. Complete obliteration of the aneurysms and patency of the parent arteries were confirmed. Partial integrity of the vessels around the lesion was also confirmed.

Magnetic Resonance Imaging (MRI) stereotaxis using the Patil System. A technical note

Magnetic Resonance Imaging (MRI) scanning would prove useful for lesions that are not visualized on computed tomography (CT) scan or are better defined on MRI scan. The problem of reference marker visualization can be overcome by coating them with mineral oil or by placing paramagnetic fluid filled rods on them. The unique construction of the Patil System permits its use even in a strong magnetic field. The technique of MRI stereotaxis using this stereotaxic system without any modification is described.

Scalp marking of intracranial lesions using computed tomography (CT) images. A technical note

A technique for scalp marking using computed tomography (CT) images is described. A reference marker is placed on the scalp and a plain lateral skull film is obtained. Using the CT scan image and the CT scout film, the target is marked on the plain skull film. The distance and angle of the target from the reference point on the plain film are measured and marked on the scalp to indicate the location of the target.

Target localization on standard axial images in computed tomography (CT) stereotaxis for functional neurosurgery--a technical note

A simple technique for marking functional neurosurgery target on computed tomography (CT) axial image is described. This permits the use of standard axial image for computed tomography (CT) stereotaxis in functional neurosurgery.

Electromagnetic field focusing (EFF) probe in aneurysm thrombosis. Preliminary report

Due to its capability of producing a well localized intense heat field of predictable dimensions, the electromagnetic field focusing probe was evaluated experimentally as a surgical tool in aneurysm thrombosis. Aneurysm models were created by anastomosing a segment of vein to the abdominal aorta. Seventy-five such aneurysms were created in seventy-five animals. The aneurysms were then placed under the solenoidal radiofrequency coil and the tip of the field focusing probe was inserted into them. Intense heat was delivered with well defined, effective and quick thrombosis and shrinkage of the aneurysm. Nineteen of the aneurysms were followed for up to one week. Histological studies were conducted showing complete thrombosis of the aneurysm with good preservation of the aorta. With further refinement of this technique, it is hoped that stereotaxic aneurysm thrombosis might be possible.

Cortically evoked motor action potential in spinal cord injury research

Somatosensory evoked potentials (SEPs) have been used extensively in the neurophysiological assessment of spinal cord integrity. However, SEPs mainly reflect the function of the dorsal column. In an effort to find a reliable method of assessing the integrity of the motor tracts for experimental purposes, we studied cortically evoked motor action potentials (CEMAPs). Twenty white rats used were anesthetized with ketamine, and extradural cortical stimulation was carried out through a parasagittal craniectomy posterior to the coronal suture. A single stimulus of 325 mV for a duration of 0.1 to 0.5 ms was used to obtain a motor action potential from the contralateral lower extremity. Complete transsection of the spinal cord abolished the CEMAP. A progressive increase in pressure applied to the spinal cord with a progressive increase in duration produced loss of the CEMAP. The selective motor tract study made possible by cortical stimulation makes this a good technique for studying the motor tracts in experimental work.

Computed tomography plane of the target approach in computed tomographic stereotaxis

A computed tomographic (CT) stereotactic system that uses the principle of bringing the reference markers and the probe holder into the CT plane of the target is described. This eliminates the need for obtaining the Z coordinate and enables one to measure directly the X and Y coordinates. The use of an arc and of a rotary arc carrier permits one to approach the target from any point on the skull. Off-axial reconstruction permits visualization of the trajectory in both the coronal and the sagittal planes.

The effect of human chorionic gonadotropin (HCG) on functional recovery of spinal cord sectioned rats

The effect of human chorionic gonadotropin (HCG) on functional recovery after complete spinal cord transection in the rat was studied. Twelve rats (6 male and 6 female) received HCG daily for the first week and then every alternate day for three weeks. Ten rats (5 male and 5 female) served as controls. Return of bladder function, Tarlov's grading and measuring the maximum angle at which the rats were able to climb up an inclined plane were used as criteria in assessing the functional recovery. Improvement was noted in the HCG-treated rats by the end of two weeks. At six weeks the recovery of HCG-treated rats as compared to the control group was very significant (p less than 0.001). No recovery whatsoever was noted in the control group even after six weeks. Histological evidence of bridging of the gap between the cut ends of the spinal cord by nerve fibres containing tissue was noted in the HCG-treated rats only. The possible mode of action of HCG on spinal cord injury is briefly discussed.

Computer tomography (CT) orientated rotary stereotactic system. A technical note

The system consists of an inverted U-shaped frame with right angled corners, so mounted that it can be adjusted vertically, antero-posteriorly and made to rotate on an axis ("the axis of the frame") formed by its free ends. The frame carries an arc probe carrier whose probe holder slides on an arc which is centered on the axis of the frame. The centre of the probe holder and axis of fram lie in one plane "The plane of probe". After positioning the patient in the frame on the CT table, using either table indexing or laser positioning light, the plane of the probe is brought in the CT plane of the target. Once in this CT plane, direct measurements can be obtained so as to bring the axis of the frame passing through the target and centering the arc on the target. The frame can then be rotated to any desired angle and the probe holder can be moved to any position on the arc without altering the direction of the probe with respect to the target. As the structures in the probe plane are constructed of plastic, it can be used within the scanner with practically no artifacts, and direct measurements can be obtained without any calculations. This system can be used in any total body scanner with standard features and no special computer programming is necessary. This is a simple and truly CT-oriented stereotactic system with a high degree of accuracy.

Angiographic disappearance and reappearance of an arteriovenous malformation of the cerebellum and brain stem, and its surgical excision. A case report

A case of arteriovenous malformation (AVM) of the cerebellum and brainstem at the cerebellopontine angle is reported. Though a postoperative angiogram after the first operation indicated complete excision of the lesion, the patient returned with subarachnoid haemorrhage, and an angiogram indicated reappearance of the lesion. Total excision was carried out at the second operation.