Biomedical subjects

Richard D Guyer

Publications and source records attributed to Richard D Guyer.

5 recordsLinked to original sources

PubMed2003

Case report: intraoperative left common iliac occlusion in a scheduled 360-degree spinal fusion.

STUDY DESIGN: This is a case report of a left common iliac artery occlusion identified as an intraoperative complication during a planned (combined anterior interbody and posterior fusion) 360 degrees spinal fusion. OBJECTIVE: The purpose of this report was to document the occurrence of this rare complication during a planned 360 degrees fusion and to increase the awareness of this potential intraoperative vascular complication. SUMMARY OF BACKGROUND DATA: Several cases of left iliac artery occlusion after anterior spinal surgery have been reported, but there has been no reported case of intraoperative iliac artery occlusion identified during a planned 360 degrees spinal fusion. METHODS: The patient was a 46-year-old woman with chronic low and mid back pain and left leg pain for several years. She was a 2-pack-a-day cigarette smoker for 30 years. She was diagnosed with internal disc disruption at L3-L4 and L4-L5, unresponsive to nonoperative treatment, and was scheduled for a 360 degrees spinal fusion. During the anterior procedure, the left iliac vessels were retracted with a Wiley retractor during the discectomy and fusion. It was noted that there was no pulse in the left common iliac artery as the anterior procedure neared completion. Intraoperative Doppler showed the left iliac artery was occluded, and a left iliac endarterectomy and thrombectomy were performed immediately. RESULTS: A significant occlusive plaque was separated distally and transected in a smooth fashion, and fresh thrombus was also removed. The procedure was successfully accomplished without any further complication with excellent restoration of arterial blood flow to the left lower extremity. Doppler study showed good triphasic flow in the iliac artery and all its branches. Because of the arterial repair, the posterior portion of the surgery was not undertaken at that time and was performed 2 weeks later. CONCLUSIONS: Early recognition and appropriate treatment can prevent serious sequelae. Great care and observation should be given to the patients before surgery, intraoperatively, as well as after surgery.

Arterial Occlusive Diseases↗

PubMed2003

Intervertebral disc prostheses.

STUDY DESIGN: This article is based on a comprehensive review of the literature related to intervertebral disc prostheses. OBJECTIVE: To compile an overview of the results and complications related to various types of lumbar and cervical disc replacements. SUMMARY OF BACKGROUND DATA: A functional disc prosthesis has been sought since the 1950s. Although there were a few early attempts, disc replacement did not become a viable therapy until the late 1980s. Devices that were used in Europe at that time are now being evaluated in the United States in clinical trials. Cervical disc replacements are currently in the early stages of development and evaluation. METHODS: A thorough literature search was conducted to identify articles published on intervertebral disc prostheses. Proceedings from conferences were reviewed as well. Articles were classified by topics, including lumbar total disc replacement, disc nucleus replacement, and cervical disc replacement. RESULTS: Results of total disc replacement are favorable, with 63-85% of patients having a good outcome. As with any procedure, issues related to patient selection, operative technique, and device size selection were learned from the early experiences with these devices. There has been only one disc nucleus replacement used in an appreciable number of patients. This has yielded good results, but there have been problems related to device displacement. There are increasing reports on the use of cervical disc replacements, but they are still in the early evaluation phases. However, as with the lumbar counterparts, new designs are being evaluated. DISCUSSION: Although still in the early phases of development, functional disc replacement will become a part of the spine surgeon's armamentarium for the treatment of patients with disc-related pain unresponsive to nonoperative care. The future in this area is exciting and bright with the introduction of new materials and new designs for implants. However, as with any new technology, there must be careful consideration of the safety of the devices, and their effectiveness will only be determined in long-term follow-up studies.

Follow-Up Studies↗

PubMed2003

Minimally invasive fusion: summary statement.

Ideally, minimally invasive surgery (MIS) allows less extensive manipulation of surrounding tissues than a conventional open procedure while accomplishing the same goals and objectives at the target structure. Long-term follow-up combined with appropriate outcome measures are necessary to prove the safety and effectiveness of MIS. For MIS procedures to be widely adopted, they must have an acceptable learning curve. Special skills are needed and are beyond those of traditional open surgery, By definition, as compared with conventional open surgeries, minimally invasive procedures typically involve smaller incisions and less extensive surgical manipulation of the tissues that surround the target structure. Ideally, once the target structure has been reached, the minimally invasive procedure should accomplish the same goals and objectives as its open surgical counterpart. Thus, although minimally invasive surgeries are aimed at reducing the morbidity associated with open surgical approaches, they should not hinder the surgeon's ability to perform a successful operation. In other words, minimal invasion should not equate to minimally effective.

Clinical Competence↗

PubMed2003

Complement membrane attack complexes in pathologic disc tissues.

STUDY DESIGN: Complement membrane attack complexes were located in lumbar spine disc tissues by immunohistochemistry. Their occurrence was compared in control discs obtained from organ donors (CD), discs showing a normal macroscopic anatomy, samples of intervertebral disc herniations (DH), and intervertebral discs found to be degenerated by discography, but not herniated (DD). OBJECTIVE: To look for a possible role of complement activation, specifically complement membrane attack complexes, an end product of the classic immune complex-mediated complement activation pathway, in disc pathophysiology. SUMMARY OF BACKGROUND DATA: Recent immunohistochemical and biochemical studies suggest a possible role for immune complexes, as observed by immunohistochemical location and biochemical assay of immunoglobulins M and G in intervertebral disc pathophysiology. Immune complexes may trigger complement activation and ultimately cell lysis. There are, however, currently no reports on complement activation in disc tissues, although immune (antigen-antibody) complexes have been demonstrated. Such immune complexes have been reported to occur on or near to disc cells in DH tissues. METHODS: Thin frozen sections of disc tissue from CD (n = 9 discs), DH (n = 58 discs), and DD (n = 11 discs) were cut and then immunostained with a monoclonal antibody to the complement membrane attack complex (C5b-9) using avidin-biotin complex (ABC) immunostaining. The presence or absence of complement membrane attack complex immunoreactivity was compared in the various subtypes of DH and also with preoperative duration of radicular pain. RESULTS: Complement membrane attack complexes could be observed in none of the CDs studied. In contrast, in more than one third of both the DH (21/58, 36.2%) and the DD (4/11, 36.4%), immunoreactivity to complement membrane attack complexes could be observed in disc cells. In DD discs, immunoreactivity to complement membrane attack complexes was most often present in anulus fibrosus samples (5/13, 38.5%). With respect to subtype of DH, complement membrane attack complexes were observed in 19 of 36 sequestrated discs (52.8%), 1 of 16 extrusions (6.3%), and 1 of 6 protrusions (16.7%). Complement membrane attack complexes were more often present with shorter pain duration (P= 0.03), but showed no relation to age. Disc cells often showed a heavy staining pattern for complement membrane attack complexes, suggesting an abundance of these complexes lodged in the membrane of the cells. CONCLUSIONS: The predominant presence of complement membrane attack complexes in sequestrated disc tissue could suggest a role in DH tissue-induced sciatica. Possibly immune (antigen-antibody) complexes, reported in previous studies, trigger the classic pathway of complement activation, with complement membrane attack complexes as the final product. Complement membrane attack complexes also appear to have some as yet undefined role in degenerated nonherniated disc tissue, with a predominant presence in the anulus fibrosus cells of such discs.

Adult↗

PubMed2002

Artificial disc: preliminary results of a prospective study in the United States.

Artificial discs have been used in Europe for many years with good results. This technology has recently been available in the United States on a limited, investigational basis. The purpose of this study is to review the preliminary results of one center's experience using the SB Charité III disc replacement. The study group consisted of the series of our first consecutive 56 patients who received the Link SB Charité III artificial disc. There were 25 men and 31 women, with a mean age of 39.9 years. All patients had single-level symptomatic disc disruption at L4-5 or L5-S1. The discs were implanted using the same approach as used for mini-open anterior lumbar interbody fusion procedures. The primary data recorded included visual analog scales (VAS) assessing pain and the Oswestry Disability Questionnaire. Data were collected pre-operatively and at 6 weeks, 3 months, 6 months, and 12 months post-operatively. Peri-operative data as well as complications were recorded. At the time of this preliminary study, 22 patients have reached the 12-month post-operative follow-up period. There was a significant improvement in the VAS and Oswestry scores at the 6-week follow-up period. These improvements were maintained throughout the 12-month follow-up period. The preliminary results of this prospective study indicate that the artificial disc yields significant improvement that is maintained during a 12-month follow-up. Data from more patients and with longer follow-up are needed to determine whether these results can be maintained in the long term.

Adolescent↗