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G Onik

Publications and source records attributed to G Onik.

At least 37 records · Page 2Linked to original sources
PubMed1989

Retrorenal colon: implications for percutaneous diskectomy.

It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary.

Adolescent↗
PubMed1989

Clinical experience with automated percutaneous lumbar discectomy.

Percutaneous automated aspiration discectomy is a new procedure for treating uncomplicated herniated lumbar discs. In a series of 200 patients, followed for up to six months, the overall success rate was 77.5%. Workers' compensation claimants, elderly patients, and patients with previous surgery can be treated successfully using percutaneous discectomy. Patients were treated on an outpatient basis. Patients returned to work significantly sooner after percutaneous discectomy than after microdiscectomy or laminectomy. No intraoperative or postoperative complications occurred.

Adult↗
PubMed1989

Prospective comparison of preoperative imaging and intraoperative ultrasonography in the detection of liver tumors.

A prospective evaluation of the accuracy of preoperative computed tomography (CT), ultrasonography (US), and angiography was performed in 54 patients undergoing resection of hepatic neoplasms. The results were compared with surgical findings and intraoperative ultrasonography (IOUS). A total of 167 lesions was seen by means of IOUS, of which preoperative US enabled detection of 127 (76%). In 48 patients CT allowed detection of 91 of 150 lesions (61%), and in 35 patients angiography showed 56 of 107 lesions (52%). When the detection rate is analyzed according to hepatic segment, the greater overall accuracy of preoperative US may be attributed to a markedly better detection rate in lateral segment of the left lobe of the liver. Lesion size also represented a factor, with preoperative US allowing detection of a greater number of small (less than 2 cm) lesions compared with CT. In patients studied with both CT and US, the combined lesion-detection rate increased to 81% in the right lobe and 76% in the left lobe. Because of this we recommend that preoperative assessment include both CT and US evaluation of the liver. IOUS showed 25% to 35% additional lesions compared with preoperative US and CT. More importantly, 40% of the lesions demonstrated by IOUS were neither visible nor palpable at surgery. We recommend that IOUS be considered in all patients in whom resection of hepatic neoplasm is planned.

Angiography↗
PubMed1989

Percutaneous automated discectomy. A new approach to lumbar surgery.

An automated technique for percutaneous lumbar discectomy applies the principle of suction cutting. The indications are leg pain greater than back pain (sciatica) and failure of all conservative therapy. The typical neurological and roentgenographic abnormalities of a contained herniated lumbar disc are mandatory. The procedure is performed with a Nucleotome (Surgical Dynamics, San Leandro, California) that is a specially designed, 2-mm blunt-tipped suction-cutting device inserted via a posterolateral approach into the affected disc using fluoroscopic control. The results that can be expected with the technique are similar to chymopapain and are in the 70% success range. Automated percutaneous discectomy has a demonstrably low morbidity and can be performed under local anesthesia on an outpatient basis.

Humans↗
PubMed1989

Automated percutaneous discectomy at the L5-S1 level. Use of a curved cannula.

Previously, a major limitation to percutaneous disc decompression to relieve symptoms of sciatica was the inability to approach the L5-S1 level. Obstruction by the iliac crest prevented the instrumentation from entering the L5-S1 disc space. In this paper, the authors describe a curved cannula which can be placed down to the L5-S1 disc space over a straight trocar that has been anchored at the annulus. The cannula bends the flexible aspiration probe back into the plane of the disc so that it is no longer obstructed by the sacral end plate. Using this system, the L5-S1 disc space was successfully removed in 90% of 30 cases.

Catheterization↗
PubMed1988

Automated percutaneous discectomy: preliminary experience.

In 1985, Onik, described a new automated lumbar disc aspiration technique that utilizes a probe with the guillotine cutting technology used in vitrectomy and arthroscopic instrumentation. The probe's small size (2 mm in diameter) minimizes the risk of nerve injury, while its automated action permits rapid, safe removal of disc material. The technique and our preliminary results in patients treated with this method are described.

Dermatologic Surgical Procedures↗
PubMed1988

CT-guided aspirations for the body: comparison of hand guidance with stereotaxis.

Forty computed tomography (CT)-assisted aspirations performed with only hand guidance were prospectively compared with 40 performed with a CT body-stereotaxic system. Although there was no statistically significant difference in lesion size and path length between the two groups, use of stereotaxis compared with hand guidance decreased by 75% the number of needle manipulations required to place a needle within a lesion. With the stereotaxic method, only 43 needle manipulations were required to confirm a needle placement in 40 lesions, with no lesion requiring more than two attempts. Use of stereotaxis decreased the number of localization scans by 80% and biopsy time by 50%. It is concluded that CT-guided needle placements with hand guidance are often inaccurate and, unless the lesion is large, require multiple needle manipulations to place a needle within the lesion. Stereotaxis-guided biopsies, on the other hand, decrease radiation exposure, biopsy time, and trauma from multiple needle punctures.

Biopsy, Needle↗
PubMed1988

US characteristics of frozen prostate.

Cryosurgery has previously been used successfully to treat prostatic carcinoma. Inability to monitor the freezing led to local complications that limited the use of this modality. In this animal study, monitoring of the freezing process was accomplished with real-time ultrasound. The margin of the frozen tissue appeared as a hyperechoic rim with posterior acoustic shadowing. The thawed cryolesions showed markedly decreased echogenicity compared with normal unfrozen prostate. These characteristic changes should allow safer and more efficacious application of prostatic cryosurgery.

Animals↗
PubMed1987

Hepatic cryosurgery with intraoperative ultrasound monitoring for metastatic colon carcinoma.

We utilized cryosurgery with intraoperative ultrasound (IOUS) monitoring in ten patients to treat multiple unresectable hepatic metastases from colorectal carcinoma. The liver was exposed at laparotomy, and tumors were subjected to three cycles of freezing (eight minutes each) and thawing. Freezing was monitored by IOUS, which visualized frozen tumor as a hyperechoic rim with posterior acoustic shadowing. Frozen normal liver appeared hypoechoic after thawing compared with normal unfrozen liver. There were no significant complications. The follow-up ranged from four months to 17 months (median, 7.5 months). Tumor response was documented by pathologic findings (coagulative necrosis), progressive fall of carcinoembryonic antigen levels, and computed tomographic scan evidence of necrosis and shrinkage of tumor. One patient underwent repeated laparotomy five months after cryosurgery and had the frozen lesions resected; there was no residual tumor. This study establishes the technical feasibility and antitumor response of hepatic cryosurgery and the use of IOUS for precise localization and monitoring of cryoablations.

Adult↗
PubMed1987

CT body stereotaxic system for placement of needle arrays.

A new CT body stereotaxic system that is particularly suited to multiple placements of needles precisely in parallel is described. By scanning through a right triangle placed on the patient's skin, the stereotaxic method defines an entry point for the first needle placement. An articulating arm is then used to aim the needle at the entry point and hold the needle at the correct angle. The arm can be angled so that the complex approaches from one scan plane to another can be made to place needle arrays through inaccessible lesions, for instance, beneath the diaphragm. Animal and phantom studies have shown that placement of multiple needle arrays in parallel from CT scan data is possible.

Biopsy, Needle↗
PubMed1987

Computed tomographic--guided stereotaxic biopsy of thoracic lesions.

A stereotaxic guidance system has been used in conjunction with a conventional CT unit to biopsy 26 consecutive thoracic lesions. Accurate needle placement with a single manipulation occurred in 24 instances and two lesions required second passes. The technique provided adequate pathologic material with an acceptable complication rate. System advantages include the ability to approach lesions along oblique paths, controlled approach in difficult locations (mediastinal, peripheral, subscapular), capacity to biopsy small nonfluoroscopically visualized lesions, and increased speed over manual techniques.

Biopsy, Needle↗
PubMed1987

Automated percutaneous diskectomy: initial patient experience. Work in progress.

A new method has been developed for percutaneously decompressing herniated lumbar disks. The method entails gaining access to the disk space through the use of an introduction system and a cannula. A 2-mm aspiration probe called a Nucleotome is then placed through the cannula into the disk space, and the nucleus pulposus is aspirated. Thirty-six patients have undergone the procedure, with a successful result in 31. There were no significant complications encountered, and the procedure is now being done on an outpatient basis. These preliminary results indicate that automated percutaneous diskectomy has the potential to replace laminectomy in the treatment of uncomplicated herniated disks.

Humans↗
PubMed1987

Percutaneous automated discectomy: a new method for lumbar disc removal. Technical note.

A new technique for percutaneous lumbar disc removal is described. The specially designed 2-mm blunt-tipped suction/cutting probe (nucleotome) is similar to the automated vitrectomy instrumentation used by ophthalmic surgeons. The procedure is performed under local anesthesia, with the patient in the prone position and with fluoroscopic guidance. The nucleotome is inserted into the appropriate disc space with specially designed instrumentation, guided by landmarks similar to those used in needle placement for chemonucleolysis. The technique has been evaluated in 20 patients with herniated discs (one at the L3-4 level and 19 at the L4-5 level) confirmed by myelography and/or computerized tomography scans after all conservative therapy for primarily radicular pain had failed. From 1 to 7 gm of disc material was removed in an average total operative time of approximately 1 hour. Eighty percent of the patients had good to excellent results in a short-term follow-up period of 6 months. Four patients subsequently required standard surgical excision of free disc fragments. No significant complications occurred. The procedure is contraindicated in patients with extruded or free fragments of disc in the spinal canal or in patients with herniations at the L5-S1 level pending development of additional instrumentation for insertion at that level. More extensive long-term studies are needed to further evaluate this procedure.

Humans↗
PubMed1986

CT body stereotaxis: an aid for CT-guided biopsies.

A new body stereotaxic system used to facilitate CT-guided biopsies is described. By scanning through a triangle placed on the patient's skin, the method defines an entry point for the biopsy. An articulating arm is then used to aim the needle at the entry point and hold the needle at the correct angle. The arm can be angled so that complex approaches from one scan plane to another can be made in order to take biopsies of lesions beneath the diaphragm. Using the system, 23 of 25 lesions were hit on the first needle manipulation; two manipulations were needed for each of the other two lesions. In comparison with previous experience, procedure time was decreased and the numbers of needle manipulations and localization scans were decreased 75% and 90%, respectively.

Biopsy, Needle↗
PubMed1986

Society of Gastrointestinal Radiologists Roscoe E. Miller Award. Monitoring hepatic cryosurgery with sonography.

The intraoperative sonographic appearance of frozen hepatic tumors and frozen normal liver was correlated with the histologic appearance of pathologic specimens from six patients. Frozen tissue was visualized as a hyperechoic rim with posterior acoustic shadowing. Normal liver that was frozen and then thawed appeared hypoechoic when compared with normal unfrozen liver. These findings allowed visualization of the extent of freezing in relation to tumor margins. Pathologically, frozen tumors showed definite evidence of necrosis. Normal liver tissue was extremely sensitive to cold and was completely necrotic after freezing. The sonographic appearance of frozen and thawed liver correlated precisely with the gross morphologic and histologic changes seen in the cryolesion. It appears that intraoperative sonography allows accurate monitoring of hepatic cryosurgery.

Carcinoma↗
PubMed1985

CT body stereotaxic instrument for percutaneous biopsy and other interventive procedures: phantom studies.

This article describes a new body stereotaxic system that defines a fiducial point by means of a skin localization device placed directly on the patient. The system uses a rectilinear stereotaxic frame to guide the needles along the calculated path. A method for calculating paths that require angulations from one scan slice to another is described, as well. The system was tested in a foam phantom and shown to be intrinsically accurate in vitro to within 2 mm in both the x and y axis.

Biopsy, Needle↗
PubMed1985

Percutaneous lumbar diskectomy using a new aspiration probe: porcine and cadaver model.

A method of percutaneous aspiration of the nucleus pulposus of lumbar disks is described as performed in four pigs and three cadavers. Through a lateral oblique percutaneous approach, 80-100% of the nucleus pulposus was removed in each of the pigs; approximately 30% of the cadaver disk was removed. A unique aspiration probe and the introducing set as well as the technique are described. The implications for clinical use in patients are discussed. We believe this technique may be an alternative to both surgical diskectomies and chymopapain injection in the treatment of herniated disk disease of the lumbar spine.

Adult↗