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Biomedical subjects

Paul Santiago

Publications and source records attributed to Paul Santiago.

8 recordsLinked to original sources
PubMed2007

Minimally invasive surgery for the management of cervical spondylosis.

Dorsal surgical procedures have a well-established role in the treatment of both radiculopathy and myelopathy caused by cervical spondylosis. Laminectomy and laminoplasty procedures can both lead to postoperative kyphosis because of the removal of the dorsal supporting structures of the neck. Minimally invasive or minimal-access spinal surgery procedures of the dorsal cervical spine are evolving techniques with the goal of decompressing the neural structures with minimal disruption of the dorsal supporting structures. We think that this will lead to less postoperative pain and a decreased incidence of post-decompression kyphotic deformity. Patient selection, techniques, and results are discussed for both minimally invasive cervical laminoforaminotomy and stenosis decompression.

Cervical Vertebrae↗
PubMed2006

Minimally invasive resection of intradural-extramedullary spinal neoplasms.

OBJECTIVE: Spinal intradural-extramedullary neoplasms are uncommon lesions that usually cause pain or neurological deficit secondary to neural compression. Traditional treatment of these tumors includes open laminectomy with intradural resection. We describe an alternative minimally invasive surgical technique in a consecutive series of patients undergoing treatment for symptomatic lesions. METHODS: Six patients (four men, two women) presented with symptoms including pain (five out of six) and/or neurological deficit (two out of six) with radiographic evidence of intradural pathology. All patients underwent surgical resection using a minimally invasive, unilateral approach. Pain relief was analyzed using the visual analog scale and magnetic resonance imaging to evaluate the extent of resection. Traditional laminectomy for tumor resection disrupts the muscular, ligamentous, and bony structures of the spine, which may contribute to pain and instability. Minimally invasive resection of intradural tumors offers the option of reducing approach morbidity when resecting these lesions. Using a tubular retractor system (X-Tube, Medtronic Sofamor-Danek, Memphis, TN) and microscopic surgical techniques, we were able to resect different intradural lesions successfully. RESULTS: All patients underwent successful, complete resection of their intradural-extramedullary tumors. The average patient age was 47 years (range, 41-60 yr) with one cervical, one thoracic, and four lumbar lesions. The mean operative time was 247 minutes (range, 180-320 min), the estimated blood loss was 56 mLs (range, 40-75 mLs), and the hospital stay was 57 hours (range, 48-80 h). Histologically, five tumors were determined to be schwannomas and one was identified as a myxopapillary ependymoma. There were no complications associated with this surgical technique. Postoperative magnetic resonance imaging demonstrated complete resection in all cases. CONCLUSION: Intradural-extramedullary neoplasms can be safely and effectively treated with minimally invasive techniques. Potential reduction in blood loss, hospitalization and disruption to local tissues suggest that, in the hands of an experienced surgeon, this technique may present an alternative to traditional open tumor resection.

Adult↗
PubMed2005

Thoracic microendoscopic discectomy: a human cadaver study.

STUDY DESIGN: Feasibility analysis of percutaneous posterolateral thoracic microendoscopic discectomy in a human cadaver model. OBJECTIVE: To describe a new, minimally invasive, posterolateral approach to the thoracic spine for the treatment of disc herniations. SUMMARY OF BACKGROUND: Thoracoscopic discectomy offers surgeons direct ventral access to thoracic disc herniations but requires entry into the chest. Many surgeons favor a posterolateral approach to the thoracic spine, thereby avoiding morbidity associated with entry into the thoracic cavity. By adapting minimal access surgical techniques to the thoracic spine, effective treatment of thoracic disc herniations should be possible and may help expedite recovery. METHODS: Two cadaveric human torsos were used. Using simple adaptations of our standard lumbar microendoscopic discectomy technique, endoscopic discectomies were performed throughout the mid and lower thoracic spine. Operative time was recorded. The extent of the discectomy as well as the extent of bony removal was evaluated using computed tomography myelography. RESULTS: Nine discectomies were performed in two cadaveric specimens, from T5-T6-T9-T10. Operative times ranged from 46 to 77 minutes (mean 60 minutes). The procedure required removing 3.4 mm (+/-1.9 mm) of the ipsilateral facet, which amounted to 35.4% (+/-17.5%) of the facet complex. Canal decompression averaged 73.5% (+/-7.9%). CONCLUSIONS: Thoracic microendoscopic discectomy allows for a posterolateral approach to thoracic disc herniation without entry into the chest cavity that consistently gives access to the majority of the canal while requiring only a minimal amount of bone removal. This technique provides an approach angle similar to that obtained with other posterolateral discectomy techniques while limiting the morbidity associated with exposure.

Arthroscopy↗
PubMed2005

Minimally invasive microendoscopy-assisted transforaminal lumbar interbody fusion with instrumentation.

OBJECT: The authors have developed a novel technique for percutaneous fusion in which standard microendoscopic discectomy is modified. Based on data obtained in their cadaveric studies they considered that this minimally invasive interbody fusion could be safely implemented clinically. The authors describe their initial experience with a microendoscopic transforaminal lumbar interbody fusion (METLIF) technique, with regard to safety in the placement of percutaneous instrumentation, perioperative morbidity, and early postoperative results. METHODS: The METLIF procedure was performed unilaterally in 20 patients with single-level lumbar spondylolisthesis or pure mechanical back pain with endoscopic assistance, hemilaminectomy, unilateral facetectomy, and microdiscectomy. Two interbody grafts were placed via the lateral exposure of the disc space. Bilateral percutaneous pedicle screws were then inserted. Compared with patients who had undergone single-level posterior LIF at the same institutions, intraoperative blood loss, hospital length of stay (LOS), and postoperative narcotic agent use were significantly lower in the METLIF group. The mean LOS for the percutaneous fusion group was 3.4 days (5.1 days in those who underwent PLIF; p < 0.02). There have been no procedure-related complications in this series to date. CONCLUSIONS: The METLIF technique provided an option for percutaneous interbody fusion similar to that in open surgery while minimizing destruction to adjacent tissues. This technique was safe and exhibited a trend toward decreased intraoperative blood loss, postoperative pain, total narcotic use, and the risk of transfusion.

Adult↗
PubMed2004

Minimally invasive surgical treatment of lumbar synovial cysts.

OBJECTIVE: Synovial cysts are a rare cause of lumbar radiculopathy and back pain. Surgical treatment is directed at complete excision of the cyst. We used minimally invasive surgical techniques for a series of patients, to assess the effectiveness of this approach for resection of synovial cysts. METHODS: Seventeen patients (10 female and 7 male patients) with presumed synovial cysts, as indicated on magnetic resonance imaging scans, underwent surgical resection with the 18-mm METRx tubular retractor system (Medtronic Sofamor Danek, Memphis, TN). A unilateral approach was used, with either an operating microscope (13 cases) or a magnifying endoscope (4 cases), depending on the preference of the surgeon. Outcomes were reported by using modified MacNab criteria. RESULTS: The average patient age was 64 years (range, 46-82 yr). The L4-L5 level was most commonly affected (82% of cases). Grade 1 spondylolisthesis at the level harboring the synovial cyst was observed for 47% of the patients; all cases of spondylolisthesis involved the L4-L5 level. The mean operative time was 97 minutes, and the average blood loss was 35 ml. Excellent or good results were achieved for 94% of the patients. A dural tear that did not violate the arachnoid membrane occurred during surgery for one patient but did not require further treatment. CONCLUSION: Synovial cysts can be effectively treated with a tubular retractor system in conjunction with an endoscope or microscope. Use of the tubular retractor minimizes soft-tissue trauma, incision length, blood loss, and disruption of ligamentous and bony structures. This may be particularly significant when synovial cysts are associated with spondylolisthesis, minimizing the risk of progressive instability and the need for fusion.

Aged↗
PubMed2003

Quantitative assessment of glioblastoma invasion in vivo.

The aim of this study was the quantitative assessment of the time course and spatial distribution in brain of invading glioblastoma (GBM) cells using a recently described model consisting of RT2 rat GBM cells stably transfected with enhanced green fluorescent protein (eGFP) - called RT2-eGFP - and implanted in Fischer rats. Invasion throughout the brain was verified by confocal microscopy and immunocytochemical staining for eGFP. Rats were sacrificed on post-implantation days 3, 8, and time of death (TOD). First, the entire rat brain was disaggregated at each time point and viable RT2-eGFP cells were counted using flow cytometry with fluorescence as the marker. Next, 2 mm(3) samples of cortex from each of four brain quadrants (bifrontal and bioccipital) were disaggregated at each time point, with tumor cell quantification as before. Tumor cell density, averaged over the entire brain, reached a peak mid-way through its time course, leveling out by TOD. Tumor cell density within bulk tumor (BT) was greatest early in the evolution of the brain tumor, decreasing to its final value mid-way through its time course, due to necrosis. The greatest concentration of tumor cells was within BT, with up to an order of magnitude fewer cells in the periphery, while the number of brain tumor cells invading brain distant from BT remained constant from day 3 until TOD. BT size steadily increased after implantation, with an increasing portion due to central necrosis as time progressed, suggesting that this effect is an important contributor to fatality in this model. Alternatively (or additionally), accumulation of toxins elaborated by tumor cells throughout the brain starting early in the evolution of the tumor may also contribute to fatality.

Animals↗
PubMed2003

The effects of hydrogen peroxide on brain and brain tumors.

BACKGROUND: Hydrogen peroxide (HP) is routinely used during neurosurgical procedures to augment hemostasis after intracranial tissue resection. Elsewhere in the body, HP is used to kill resection margin tumor cells; in vitro studies support these clinical uses. The effects of HP on brain and brain tumors have not been evaluated. In this study, the in vitro and in vivo effects of HP on both rat and human brain parenchyma and brain tumors were examined. METHODS: Antitumor activity of varied concentrations of HP (0-30%) on cultured primary and metastatic brain tumors (n = 13) was compared with the effects of various concentrations of ethanol (0-50%). Studies were performed in rats to characterize HP-induced tissue changes that occurred when HP-soaked pledgets were placed on the arachnoid surface and along resection margins (n = 5). Additionally, the effect of HP on human brain along tumor resection cavities was investigated (n = 10). RESULTS: While HP demonstrated concentration-dependent tumoricidal effects in vitro, similar to results achieved with ethanol, HP caused significant injury to arachnoid and stroma with neuronal and glial injury to a depth of 1 mm in rats. Three percent HP-soaked pledgets placed in resection cavities of excised brain tumors induced similar injury in human brain. CONCLUSION: HP irreversibly damages mesothelial and neural tissue. Although HP appears to have tumoricidal effects in vitro, it should be used with caution in humans because of risks of collateral injury to surrounding normal brain. HP may prove most beneficial for discrete lesions, such as pituitary tumors and metastases.

Animals↗