Michael Y. Wang

Clinical and radiographic comparison of mini-open transforaminal lumbar interbody fusion with open transforaminal lumbar interbody fusion in 42 patients with long-term follow-up: Clinical article

OBJECT As minimally invasive approaches gain popularity in spine surgery, clinical outcomes and effectiveness of mini-open transforaminal lumbar interbody fusion (TLIF) compared with traditional open TLIF have yet to be established. The authors retrospectively compared the outcomes of patients who underwent mini-open TLIF with those who underwent open TLIF. METHODS Between 2003 and 2006, 42 patients underwent TLIF for degenerative disc disease or spondylolisthesis; 21 patients underwent mini-open TLIF and 21 patients underwent open TLIF. The mean age in each group was 53 years, and there was no statistically significant difference in age between the groups (p = 0.98). Data were collected perioperatively. In addition, complications, length of stay (LOS), fusion rate, and modified Prolo Scale (mPS) scores were recorded at routine intervals. RESULTS No patient was lost to follow-up. The mean follow-up was 24 months for the mini-open group and 34 months for the open group. The mean estimated blood loss was 194 ml for the mini-open group and 505 ml for the open group (p < 0.01). The mean LOS was 3 days for the mini-open group and 5.5 days for the open group (p < 0.01). The mean mPS score improved from 11 to 19 in the mini-open group and from 10 to 18 in the open group; there was no statistically significant difference in mPS score improvement between the groups (p = 0.19). In the mini-open group there were 2 cases of transient L-5 sensory loss, 1 case of a misplaced screw that required revision, and 1 case of cage migration that required revision. In the open group there was 1 case of radiculitis as well as 1 case of a misplaced screw that required revision. One patient in the mini-open group developed a pseudarthrosis that required reoperation, and all patients in the open group exhibited fusion. CONCLUSIONS Mini-open TLIF is a viable alternative to traditional open TLIF with significantly reduced estimated blood loss and LOS. However, the authors found a higher incidence of hardware-associated complications with the mini-open TLIF.

Minimally invasive surgery for thoracolumbar spinal deformity: initial clinical experience with clinical and radiographic outcomes.

OBJECT Adult degenerative scoliosis can be a cause of intractable pain, decreased mobility, and reduced quality of life. Surgical correction of this problem frequently leads to substantial clinical improvement, but advanced age, medical comorbidities, osteoporosis, and the rigidity of the spine result in high surgical complication rates. Minimally invasive surgery is being applied to this patient population in an effort to reduce the high complication rates associated with adult deformity surgery. METHODS A retrospective study of 23 patients was undertaken to assess the clinical and radiographic results with minimally invasive surgery for adult thoracolumbar deformity surgery. All patients underwent a lateral interbody fusion followed by posterior percutaneous screw fixation and possible minimally invasive surgical transforaminal lumbar interbody fusion if fusion near the lumbosacral junction was necessary. A mean of 3.7 intersegmental levels were treated (range 2-7 levels). The mean follow-up was 13.4 months. RESULTS The mean preoperative Cobb angle was 31.4 degrees , and it was corrected to 11.5 degrees at follow-up. The mean blood loss was 477 ml, and the operative time was 401 minutes. The mean visual analog scale score improvement for axial pain was 3.96. Clear evidence of fusion was seen on radiographs at 84 of 86 treated levels, with no interbody pseudarthroses. Complications included 2 returns to the operating room, one for CSF leakage and the other for hardware pullout. There were no wound infections, pneumonia, deep venous thrombosis, or new neurological deficits. However, of all patients, 30.4% experienced new thigh numbness, dysesthesias, pain, or weakness, and in one patient these new symptoms were persistent. CONCLUSIONS The minimally invasive surgical treatment of adult deformities is a promising method for reducing surgical morbidity. Numerous challenges exist, as the surgical technique does not yet allow for all correction maneuvers used in open surgery. However, as the techniques are advanced, the applicability of minimally invasive surgery for this population will likely be expanded and will afford the opportunity for reduced complications.

A comprehensive review of the safety profile of bone morphogenetic protein in spine surgery.

WE REVIEW OUR current understanding of the development and potential clinical applications of bone morphogenetic protein (BMP) in spine surgery. We also review the evidence for adverse events associated with the use of BMP and suggest potential reasons for these events and means of complication avoidance. Bone morphogenetic protein 2 (rhBMP-2) is approved by the Food and Drug Administration for anterior lumbar interbody fusion; rhBMP-7, on the other hand, is approved for long bone defects and has received a humanitarian device exemption for revision posterolateral lumbar operations and recalcitrant long bone unions. Nevertheless, “off-label” use in various spinal procedures has been reported and is increasing in frequency. Specific guidelines for rhBMP-2 and rhBMP-7 use are lacking because of the limited availability of randomized controlled clinical trials and its diverse use in many spinal applications. Mechanisms of delivery, carrier type, graft position, surgical location, and variations in BMP concentration may differ from one surgery to the next. Adverse events linked to either rhBMP-2 or rhBMP-7 use include ectopic bone formation, bone resorption or remodeling at the graft site, hematoma, neck swelling, and painful seroma. Other potential theoretical concerns include carcinogenicity and teratogenic effects. In this review, we provide the reader with a historical perspective on BMP, current and past research to support its use in spinal procedures, and a critical analysis of the complications reported thus far.

An analysis of postoperative thigh symptoms after minimally invasive transpsoas lumbar interbody fusion: Clinical article

OBJECTIVE The minimally invasive transpsoas interbody fusion technique requires dissection through the psoas muscle, which contains the nerves of the lumbosacral plexus posteriorly and genitofemoral nerve anteriorly. Retraction of the psoas is becoming recognized as a cause of transient postoperative thigh pain, numbness, paresthesias, and weakness. However, few reports have described the nature of thigh symptoms after this procedure. METHODS The authors performed a review of patients who underwent the transpsoas technique for lumbar spondylotic disease, disc degeneration, and spondylolisthesis treated at a single academic medical center. A review of patient charts, including the use of detailed patient-driven pain diagrams performed at equal preoperative and follow-up intervals, investigated the survival of postoperative thigh pain, numbness, paresthesias, and weakness of the iliopsoas and quadriceps muscles in the follow-up period on the ipsilateral side of the surgical approach. RESULTS Over a 3.2-year period, 59 patients underwent transpsoas interbody fusion surgery. Of these, 62.7% had thigh symptoms postoperatively. New thigh symptoms at first follow-up visit included the following: burning, aching, stabbing, or other pain (39.0%); numbness (42.4%); paresthesias (11.9%); and weakness (23.7%). At 3 months postoperatively, these percentages decreased to 15.5%, 24.1%, 5.6%, and 11.3%, respectively. Within the patient sample, 44% underwent a 1-level, 41% a 2-level, and 15% a 3-level transpsoas operation. While not statistically significant, thigh pain, numbness, and weakness were most prevalent after L4-5 transpsoas interbody fusion at the first postoperative follow-up. The number of lumbar levels that were surgically treated had no clear association with thigh symptoms but did correlate directly with surgical time, intraoperative blood loss, and length of hospital stay. CONCLUSIONS Transpsoas interbody fusion is associated with high rates of immediate postoperative thigh symptoms. While larger, prospective studies are necessary to validate these findings, the authors found that half of the patients had symptom resolution at approximately 3 months postoperatively and more than 90% by 1 year.

Clinical Outcomes Using Modest Intravascular Hypothermia After Acute Cervical Spinal Cord Injury

BACKGROUNDAlthough a number of neuroprotective strategies have been tested after spinal cord injury (SCI), no treatments have been established as a standard of care. OBJECTIVEWe report the clinical outcomes at 1-year median follow-up, using endovascular hypothermia after SCI and a detailed analysis of the complications. METHODSWe performed a retrospective analysis of American Spinal Injury Association and International Medical Society of Paraplegia Impairment Scale (AIS) scores and complications in 14 patients with SCI presenting with a complete cervical SCI (AIS A). All patients were treated with 48 hours of modest (33°C) intravascular hypothermia. The comparison group was composed of 14 age- and injury-matched subjects treated at the same institution. RESULTSSix of the 14 cooled patients (42.8%) were incomplete at final follow-up (50.2 [9.7] weeks). Three patients improved to AIS B, 2 patients improved to AIS C, and 1 patient improved to AIS D. Complications were predominantly respiratory and infectious in nature. However, in the control group, a similar number of complications was observed. Adverse events such as coagulopathy, deep venous thrombosis, and pulmonary embolism were not seen in the patients undergoing hypothermia. CONCLUSIONThis study is the first phase 1 clinical trial on the safety and outcome with the use of endovascular hypothermia in the treatment of acute cervical SCI. In this small cohort of patients with SCI, complication rates were similar to those of normothermic patients with an associated AIS A conversion rate of 42.8%.

Intradural spinal arachnoid cysts in adults.

BACKGROUND Idiopathic arachnoid cysts are rare lesions not associated with trauma or other inflammatory insults. To date, there have been few large series describing the presentation and management of these lesions. METHODS Twenty-one cases of intradural spinal arachnoid cysts were identified (1994-2001). Pediatric patients and cases with antecedent trauma were excluded. There were eight women and 13 men with an average age of 52 years. Follow-up averaged 17 months. RESULTS Cysts were most commonly found in the thoracic spine (81%). Fifteen cysts were dorsal to the spinal cord and six were ventral to the spinal cord. All patients underwent laminectomy with cyst fenestration and radical cyst wall resection. Based upon intraoperative ultrasonography, four cysts were also shunted to the subarachnoid space, and seven patients had an expansile duraplasty with freeze-dried dural allograft. Of the seven patients with syringomyelia, three resolved with extramedullary cyst resection alone. Four required syrinx to subarachnoid shunting. Follow-up MRI demonstrated cyst resolution in all cases. All seven intramedullary syrinxes were decreased in size and four resolved completely. Weakness (100%), hyperreflexia (91%), and incontinence (80%) were more likely to improve than neuropathic pain (44%) and numbness (33%). One patient had increased numbness postoperatively. CONCLUSIONS Ventral cysts are more likely to cause weakness and myelopathic signs. Preoperative symptoms of neuropathic pain and numbness are less likely to improve than weakness and myelopathy. Utilizing intraoperative ultrasound to guide aggressive surgical treatment with the adjuncts of shunting and duraplasty results in a high rate of cyst and syrinx obliteration.

An analysis of the differences in the acute hospitalization charges following minimally invasive versus open posterior lumbar interbody fusion

OBJECT Minimally invasive spine (MIS) procedures are increasingly being recognized as equivalent to open procedures with regard to clinical and radiographic outcomes. These techniques are also believed to result in less pain and disability in the immediate postoperative period. There are, however, little data to assess whether these procedures produce their intended result and even fewer objective data to demonstrate that they are cost effective when compared with open surgery. METHODS The authors performed a retrospective analysis of hospital charges for 1- and 2-level MIS and open posterior interbody fusion for lumbar spondylotic disease, disc degeneration, and spondylolisthesis treated at a single academic medical center. Patients presenting with bilateral neurological symptoms were treated with open surgery, and those with unilateral symptoms were treated with MIS. Overall hospital charges and surgical episode-related charges, length of stay (LOS), and discharge status were obtained from the hospital finance department and adjusted for multi-/single-level surgeries. RESULTS During a 14-month period, 74 patients (mean age 55 years) were treated. The series included 59 single-level operations (75% MIS and 25% open), and 15 2-level surgeries (53% MIS and 47% open). The demographic profile, including age and Charlson Comorbidity Index, were similar between the 4 groups. The mean LOS for patients undergoing single-level surgery was 3.9 and 4.8 days in the MIS and open cases, respectively (p = 0.017). For those undergoing 2-level surgery, the mean LOS was 5.1 for MIS versus 7.1 for open surgery (p = 0.259). With respect to hospital charges, single-level MIS procedures were associated with an average of

Clinical application of modest hypothermia after spinal cord injury.

70,159 compared with

Motor nerve injuries following the minimally invasive lateral transpsoas approach

78,444 for open surgery (p = 0.027). For 2-level surgery, mean charges totalled

CADAVERIC MORPHOMETRIC ANALYSIS FOR ATLANTAL LATERAL MASS SCREW PLACEMENT

87,454 for MIS versus