Biomedical subjects
G Onik
Publications and source records attributed to G Onik.
Effect of thermal variables on frozen human primary prostatic adenocarcinoma cells.
OBJECTIVES: Recent advances in imaging technology and cryotechnology have rekindled interest in prostate cryosurgery. Cryosurgery, however, cannot be applied precisely without knowing how the thermal variables used during the procedure affect tissue destruction. The goal of this article is to provide quantitative values for the relationship between thermal variables during freezing and the destruction of human primary prostatic adenocarcinoma cells. METHODS: Human primary prostatic adenocarcinoma cells were frozen with controlled thermal parameters, using a directional solidification apparatus. Cell viability was determined after thawing, using trypan blue and a two-dye fluorescent test and correlated to the thermal variables used during freezing. RESULTS: Human primary prostatic adenocarcinoma cells are damaged by intracellular chemical damage when frozen with cooling rates lower than 5 degrees C/min and by intracellular ice formation when frozen with cooling rates higher than 25 degrees C/min. A double freeze/thaw cycle is required to ensure complete cell destruction at high subzero temperatures, which must be lower than -40 degrees C for the low cooling rates and lower than -19 degrees C for the higher cooling rate. CONCLUSIONS: Haphazard freezing does not necessarily destroy tissue during cryosurgery; however, quantitative data on the relation between thermal variables and frozen cell destruction can provide the means for performing cryosurgery more precisely and with greater control over the outcome of the procedure.
Automated percutaneous biopsy in the diagnosis and treatment of infectious discitis.
The author's experience using automated disc aspiration for the diagnosis of discitis indicates that skinny needle aspiration biopsy has a very high false-negative rate. A negative skinny-needle biopsy, therefore, must be followed by a procedure to obtain a better sample of pathologic material. Automated disc aspiration, because of its safety and ability to provide a large specimen, is the procedure of choice. Attention, however, must be paid to technical details of the procedure and the poor annular integrity of the infected disc to carry out the procedure safely.
Three-dimensional prostate ultrasound and its application to cryosurgery.
Transrectal ultrasound (TRUS), despite its undeniable utility in prostate imaging, employs a spatially flexible and variable 2-dimensional (2-D) imaging technique to visualize a 3-dimensional (3-D) disease process and anatomy. To circumvent some of the limitations of 2-D TRUS, 3-D TRUS was developed. The system consists of a motorized assembly (to hold a standard ultrasound transducer) and a computer with a video frame grabber. The microcomputer, using software developed in our laboratory, rapidly reconstructs a series of linear ultrasound images into a 3-D image. The 3-D TRUS technology has been incorporated into our program for cryoablation of the prostate. With intraoperative 3-D TRUS providing a unique coronal view, cryoprobe placement is facilitated to detect malalignment and avoid subsequent suboptimal cryoablation. In our use of 3-D TRUS guidance, in all 21 initial patients, probe malalignment, otherwise not apparent on standard 2-D TRUS, was detected and corrected before cryosurgery. With median follow-up of just < 1 year, only 2 of 44 biopsy cores (from the same site of 1 patient) were positive at 3 and 6 months. 3-D TRUS appears to be a valuable adjunctive tool in prostate imaging, especially in providing guidance for cryoblation of prostate cancer.
Percutaneous anterior discectomy under ultrasound guidance.
The object of this experiment was to demonstrate that, by using a peritoneal fluid infusion coupled with ultrasound guidance, a safe anterior entry into the L5-S1 disc of the pig could be made. The goal was to develop a procedure with the advantages of a laparoscopic approach to the disc which has been published to allow removal of extruded herniations, that a neurosurgeon could perform without a general surgeon in attendance. The procedure was carried out under general anesthesia and fluoroscopic control. One liter of normal saline was then infused into the abdomen of a pig. Under ultrasound guidance and laparoscopic confirmation, a Nucleotome was placed into the L5-S1 disc and the disc was aspirated. The results showed that the disc was safely entered in all 5 pigs. The disc was successfully removed in 4 of 5 pigs. In all animals the bowel floated out of the pelvis, obviating the need for bowel manipulation. Laparoscopic ultrasound was needed for visualization in 3 pigs, while external ultrasound was used in two. Our conclusion is that peritoneal fluid infusion and ultrasound guidance, when applied to laparoscopic anterior discectomy, eliminates the need for retroperitoneal dissection and bowel manipulation, significantly simplifying the laparoscopic discectomy procedure.
Percutaneous discectomy for lumbar disc herniation.
Percutaneous discectomy for lumbar disc herniation is a well established, low-risk procedure effective in 70% to 80% of appropriately selected patients. Advantages include the use of local anesthesia, minimal tissue disruption, no epidural fibrosis or scarring, and negligible biomechanical effect. The risk of automated percutaneous lumbar discectomy is significantly less than that of traditional surgery.
Cryosurgery re-visited for the removal and destruction of brain, spinal and orbital tumours.
Advances in neuroimaging and cryosurgical techniques have prompted us to re-evaluate the potential of cryosurgical techniques for the removal and the destruction of various neoplasms. We have used cryosurgical instrumentation to remove tumours in the brain, spine and orbit in 71 patients without complications. Cryosurgery was used to facilitate removal and extraction in 64 and to destroy residual neoplasms when removal was incomplete in 7. Intraoperative real time ultrasonic imaging permitted precise delimitation of tumours from surrounding tissues and allowed monitoring during the production of cryosurgical lesions thus permitting heretofore unavailable visualization of the production of cryogenic lesions in the central nervous system. New cryosurgical instrumentation was used to produce lesions up to three times larger than similar sized probes previously available. Our results reconfirm that cryosurgery facilitates the removal of tumours in the brain, spinal cord and orbit, reduces blood loss in vascular tumours, and is effective in ablating residual neoplasms involving the superior sagittal sinus, torcula and parasagittal areas. A Doppler flowmeter proved useful for monitoring sagittal sinus blood flow during the production of cryosurgical ablation of residual tumour attached to the walls of the sagittal sinus. Recent advances in ultrasonic and neuroimaging coupled with stereotactic techniques and improvements in cryosurgical instrumentation may prove useful in the future percutaneous destruction of selective intracranial neoplasms.
Cauda equina syndrome secondary to an improperly placed nucleotome probe.
Automated percutaneous lumbar discectomy has been shown to be a low morbidity procedure in the treatment of contained herniated lumbar discs. Described in this paper is a complication, i.e., a cauda equina syndrome secondary to a Nucleotome probe improperly placed in the thecal sac. The authors reemphasize the landmarks for the thecal sac, i.e., the medial border of the pedicles, and discuss the preventable nature of this type of complication.
Ultrasound-guided hepatic cryosurgery in the treatment of metastatic colon carcinoma. Preliminary results.
Cryosurgery, the in situ freezing of cancer, has been proposed in the past as a possible treatment for unresectable hepatic tumors. Its advantage lies in the fact that it is a very focal treatment sacrificing less normal tissue than surgical resection, allowing treatment of multiple lobes. Because cryosurgery does not affect large vessels, tumors in difficult locations, such as adjacent to the inferior vena cava (IVC), can be treated. With the use of intraoperative ultrasound to place the cryoprobes and monitor the freezing process, 18 patients with unresectable metastatic colon carcinoma confined to the liver were treated. Of the 18 patients treated, 4 (22%) are in complete remission as determined by computed tomography (CT) scans and carcinoembryonic antigen (CEA) levels, with a mean follow-up of 28.8 months. Four patients (22%) were not adequately treated at the time of cryosurgery. The number of lesions frozen in each patient ranged from 1 to 12, with a mean of 6 lesions. Fourteen patients had bilobar disease; three patients had previous right lobectomies with recurrences in their remaining left lobes prior to cryosurgery, and one patient had unilobar disease. Mean survival of the 14 cases with recurrence was 21.4 months, with 2 of the 14 still alive. Ultrasound-guided hepatic cryosurgery appears to be an effective treatment for metastatic colon carcinoma to the liver that is unresectable (including patients with bilobar and multiple lesions). These preliminary results indicate that the procedure warrants further study.
Percutaneous transperineal prostate cryosurgery using transrectal ultrasound guidance: animal model.
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. Recent studies have shown that monitoring of the freezing process can be accomplished using real-time ultrasound. In this study, transrectal ultrasound guidance was used to guide a cryoprobe percutaneously, using a transperineal approach, into the prostate. The extent of freezing was then monitored using ultrasound, taking care not to freeze the urethra or the rectum. Six dogs had the procedure without any complications. This study demonstrates the feasibility of a noninvasive treatment for prostatic carcinoma.
Automated percutaneous discectomy.
Automated percutaneous discectomy is a new, safe procedure for treating herniated lumbar discs still contained by the annulus or posterior longitudinal ligament. In 1985, one of the authors reported a percutaneous nucleus aspiration technique using a 2-mm aspiration probe. This small probe produced minimal tissue damage, allowing the procedure to be done on an outpatient. In this series, 518 patients were treated using this technique for an overall success rate of 85%. Compensation patients, elderly patients, and patients with previous surgery were treated successfully using percutaneous discectomy on an outpatient basis. No intraoperative or postoperative complications occurred.
Automated percutaneous lumbar diskectomy.
The use of automated percutaneous lumbar diskectomy for the treatment of herniated lumbar disks is increasing. More than 3000 physicians have been trained to perform the procedure, and over 40,000 cases have been completed worldwide. This review describes the development of automated percutaneous lumbar diskectomy, the selection of appropriate patients, how the technique is performed, and its efficacy relative to other methods of treatment.
Automated percutaneous lumbar diskectomy.
Automated percutaneous lumbar diskectomy was introduced in 1985. Development of this technique was instigated by the general trend in medicine toward less invasive procedures. Technique, indications, patient selection, and a review of the current literature are presented. Cumulative data indicate that the procedure has the least potential to do harm compared to open operations for treating lumbar disk herniations.
The process of freezing and the mechanism of damage during hepatic cryosurgery.
Experiments were performed to correlate the structures of liver tissue frozen during cryosurgery, liver frozen at various constant cooling rates, and unfrozen, dried normal liver. The results show that during freezing of tissue ice forms and propagates along the vascular system, expanding during freezing at low cooling rates. This expansion occurs over most of the region frozen during cryosurgery and may be one of the mechanisms of damage to tissue during cryosurgery.
Percutaneous automated biopsy in the diagnosis of primary infectious spondylitis.
Three cases of primary infectious spondylitis, two caused by Staphylococcus aureus and one by tuberculosis, were diagnosed using the method previously described for automated percutaneous discectomy. All three patients, in whom biopsy using fine needle techniques previously was unsuccessful, had positive cultures from specimens obtained using the automated method. The method combines the advantages of local anesthesia and minimal morbidity with the obtaining of adequate material for culture and pathological examination.
Automated percutaneous discectomy: a prospective multi-institutional study.
A prospective multi-institutional study was carried out to evaluate automated percutaneous discectomy in the treatment of lumbar disc herniations. Of the 327 patients who prospectively met the study criteria and were followed for longer than 1 year, 75.2% were successfully treated. When patients (n = 168) who prospectively did not meet the study criteria were treated, the success rate was 49.4%. One case of discitis was reported; otherwise, no other serious complications were noted, and specifically no vascular or nerve damage was encountered. This study indicates that automated percutaneous discectomy can be used successfully to treat lumbar disc herniations with minimal morbidity and emphasizes the need for proper patient selection.
Automated percutaneous lumbar discectomy.
Lumbar spine disc disease has traditionally been treated surgically by laminectomy and manual removal of the offending disc material. Chymopapain was extensively used to decompress the disc pressure in a relatively noninvasive manner, but has been abandoned due to serious complications, including anaphylaxis and paraplegia. Onik introduced automated percutaneous discectomy in 1985. This procedure has proved safe and efficacious for treating lumbar disc disease without complications. It is performed on an out-patient basis under local anesthesia with minimal rehabilitation time. The success rate reported in a multiinstitutional study with one year follow-up is approximately 75%. The majority of failures occur in patients with free fragments or spinal stenosis - both of which can be diagnosed preoperatively with good imaging examinations. Hence, the success rate can be expected to improve if preoperative imaging is relied upon to help choose appropriate patients. Over 30,000 percutaneous discectomy procedures have been performed. The only complication reported, disc infection, developed in fewer than 0.2% of cases. Automated percutaneous discectomy has the potential to treat a vast number of patients with lumbar disc disease who otherwise would have laminectomies.
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.