Neil Duggal

Epidemiology of traumatic spinal cord injury in Canada.

Study Design. Retrospective review. Objective. To describe the incidence, clinical features, and treatment of traumatic spinal cord injury (SCI) treated at a Canadian tertiary care center. Summary of Background Data. Understanding the current epidemiology of acute traumatic SCI is essential for public resource allocation and primary prevention. Recent reports suggest that the mean age of patients with SCI may be increasing. Methods. We retrospectively reviewed hospital records on all patients with traumatic SCI between January 1997 and June 2001 (n = 151). Variables assessed included age, gender, length of hospitalization, type and mechanism of injury, associated spinal fractures, neurologic deficit, and treatment. Results. Annual age-adjusted incidence rates were 42.4 per million for adults aged 15–64 years, and 51.4 per million for those 65 years and older. Motor vehicle accidents accounted for 35% of SCI. Falls were responsible for 63% of SCI among patients older than 65 years and for 31% of injuries overall. Cervical SCI was most common, particularly in the elderly, and was associated with fracture in only 56% of cases. Thoracic and lumbar SCI were associated with spinal fractures in 100% and 85% of cases, respectively. In-hospital mortality was 8%. Mortality was significantly higher among the elderly. Treatment of thoracic and lumbar fractures associated with SCI was predominantly surgical, whereas cervical fractures were equally likely to be treated with external immobilization alone or with surgery. Conclusion. A large proportion of injuries was seen among older adults, predominantly as a result of falls. Prevention programs should expand their focus to include home safety and avoidance of falls in the elderly.

Kinematic analysis of the cervical spine following implantation of an artificial cervical disc.

Study Design. Prospective cohort study. Objective. To assess the biomechanical profile of the cervical spine following cervical arthroplasty. Summary of Background Data. Spinal arthroplasty offers the promise of maintaining functional spinal motion, thereby potentially avoiding adjacent segment disease. Disc replacement may become the next gold standard for the treatment of degenerative cervical spine disease, and must be studied rigorously to ensure in vivo efficacy and safety. Methods. A total of 20 patients underwent single or 2-level implantation of the Bryan® artificial cervical disc (Medtronic Sofamor Danek, Memphis TN) for treatment of cervical degenerative disc disease producing radiculopathy and/or myelopathy. Lateral neutral, flexion, and extension cervical radiographs were obtained before surgery and at intervals up to 24 months after surgery. Kinematic parameters, including sagittal rotation, horizontal translation, change in disc height, and center of rotation (COR), were assessed for each spinal level using quantitative motion analysis software. Results. Motion was preserved in the operated spinal segments (mean range of motion 7.8°) up to 24 months following surgery. The relative contribution of each spinal segment to overall spinal sagittal rotation differed depending on whether the disc was placed at C5–C6 or C6–C7. Overall cervical motion (C2–C7) was moderately but significantly increased during late follow-up. Sagittal rotation, anterior and posterior disc height, translation, and COR coordinates did not change significantly following surgery. The COR was most frequently located posterior and inferior to the center of the disc space. Conclusions. The Bryan® artificial cervical disc provided in vivo functional spinal motion at the operated level, reproducing the preoperative kinematics of the spondylotic disc.

Microscopic versus endoscopic pituitary surgery: a systematic review.

To critically review current literature comparing microscopic versus endoscopic surgery in the treatment of pituitary adenomas.

Wrong-sided and wrong-level neurosurgery: a national survey

OBJECT Perhaps the single greatest error that a surgeon hopes to avoid is operating at the wrong site. In this report, the authors describe the incidence and possible determinants of incorrect-site surgery (ICSS) among neurosurgeons. METHODS The authors asked neurosurgeons to complete an anonymous survey. These surgeons were asked to report the number of craniotomies and lumbar and cervical discectomies performed during the previous year, as well as whether ICSS had occurred. They were also asked detailed questions regarding the potential determinants of ICSS. RESULTS There was a 75% response rate and a 68% survey completion rate. Participating neurosurgeons performed 4695 lumbar and 2649 cervical discectomies, as well as 10,203 craniotomies. Based on this self-reporting, the incidence of wrong-level lumbar surgery was estimated to be 12.8 [corrected] occurrences per 10,000 operations. The ICSSs per 10,000 cervical discectomies and craniotomies were 7.6 [corrected] and 2.0, [corrected] respectively. Neurosurgeons recognized fatigue, unusual time pressure, and emergent operations as factors contributing to ICSS. For spine surgery, in particular, unusual patient anatomy and a failure to verify the operative site by radiography were also commonly reported contributors. CONCLUSIONS Neurosurgical ICSSs do occur, but are rare events. Although there are significant limitations to the survey-based methodology, the data suggest that the prevention of such errors will require neurosurgeons to recognize risk factors and increase the use of intraoperative imaging.

Magnetic resonance imaging clarity of the Bryan, Prodisc-C, Prestige LP, and PCM cervical arthroplasty devices.

Study Design. Prospective, randomized, controlled and double-blinded study on imaging of artificial discs. Objective. The purpose of this study is to compare postoperative imaging characteristics of the 4 currently available cervical arthroplasty devices at the level of implantation and at adjacent levels. Summary of Background Data. Cervical arthroplasty is being performed increasingly frequently for degenerative disc disease and, in most cases, with frank neural compression. Unlike lumbar arthroplasty, performed mainly for axial back pain, decompression of neural elements may need to be confirmed with postoperative imaging after cervical arthroplasty. Methods. Preoperative and postoperative magnetic resonance imaging scans of 20 patients who had undergone cervical arthroplasty were assessed for imaging quality. Five cases each of the Bryan® (Medtronic Sofamor Danek, Memphis, TN), Prodisc-C® (Synthes Spine, Paoli, PA), Prestige LP® (Medtronic Sofamor Danek), and PCM® devices (Cervitech, Rockaway, NJ) were analyzed. Six blinded spinal surgeons scored twice sagittal and axial T2-weighted images using the Jarvik 4-point scale. Statistical analysis was performed comparing quality before surgery and after disc implantation at the operated and adjacent levels and between implant types. Results. Moderate intraobserver and interobserver reliability was noted. Preoperative images of patients in all implant groups had high-quality images at operative and adjacent levels. The Bryan® and Prestige LP® devices allowed satisfactory visualization of the canal, exit foramina, cord, and adjacent levels after arthroplasty. Visualization was significantly impaired in all PCM® and Prodisc-C® cases at the operated level in both the spinal canal and neural foramina. At the adjacent levels, image quality was statistically poorer in the PCM® and Prodisc-C® than those of Prestige LP® or Bryan®. Conclusions. Postoperative visualization of neural structures and adjacent levels after cervical arthroplasty is variable among current available devices. Devices containing nontitanium metals (cobalt-chrome-molybdenum alloys in the PCM® and Prodisc-C®) prevent accurate postoperative assessment with magnetic resonance imaging at the surgical and adjacent levels. Titanium devices, with or without polyethylene (Bryan® disc or Prestige LP®), allow for satisfactory monitoring of the adjacent and operated levels. This information is crucial for any surgeon who wishes to assess adequacy of neural decompression and where monitoring of adjacent levels is desired.

Surgical treatment of C2 fractures in the elderly: a multicenter retrospective analysis.

Study Design Multicenter retrospective analysis. Objectives To review the results of surgical treatment during the last 6 years of C2 fractures in patients over the age of 70. Summary of Background Data Little information exists about the clinical outcome of surgical treatment of elderly patients with C2 fractures, their ability to return to their previous environment, and their postoperative level of independence. Methods The medical records and radiographs of 29 patients who had undergone surgical treatment for C2 fractures were reviewed. The type of C2 fracture, neurologic examination at presentation, type of surgical treatment, perioperative morbidity and mortality, presence of osseous union, and stability of alignment were recorded. Long-term disposition was determined from office visits or by telephone interview. Results Twenty-four of 29 patients had type II dens fractures alone. The remaining 5 had associated C1 fractures. All patients were neurologically intact at presentation except for 2 patients with signs and symptoms of central cord syndrome. Perioperative complications occurred in 3 patients (10.3%). One patient died on postoperative day 6 from a myocardial infarction. Mean±SD radiographic follow-up was 9±3.2 months (range, 3 to 24). Of the 16 patients who underwent odontoid screw fixation, 6 (37.5%) had osseous union, and 9 (56.2%) were stable on radiographs. An additional patient who had odontoid screw initially required a posterior approach reoperation. Of the 13 posterior fusions, 4 (30.7%) had osseous unions and 9 (69.2%) were stable on flexion extension radiographs. Mean±SD clinical follow-up was 18±2.2 months (range, 3 to 72 mo). Twenty-five of 29 patients (86.2%) returned to their previous environment. Two patients died of unrelated etiology. Conclusions C2 fractures in the elderly can be treated surgically with both anterior and posterior approaches with acceptable morbidity and mortality rates. The majority of patients can be mobilized early and return to their previous levels of independence.

Segmental malalignment with the Bryan Cervical Disc prosthesis-contributing factors

Part 1 of the current study found that use of the Bryan Cervical Disc prosthesis resulted in a median loss of 2 degrees in functional spinal unit (FSU) lordosis when compared with preoperative imaging (P<0.0001, range: 8-degree loss to 5-degree gain). The observed changes were generally small but varied among both the patients and the surgeons, suggesting that variables may exist which affect postoperative sagittal alignment. The aim of the current study was to identify which, if any, of a range of patient and surgical variables may contribute significantly to postoperative FSU malalignment. The change in FSU angulation between the preoperative and postoperative neutral, erect x-rays of 67 consecutive patients (88 disc levels) were correlated with 35 demographic and radiographic variables. Postoperative change in disc space height, angle of prosthesis insertion, and the amount of bone removed from the anterior aspect of the cephalad vertebra varied significantly among the 3 surgeons and correlated with change in FSU alignment. Intraoperative disc space distraction correlated with subsequent loss of disc space height. Multiple linear regression analysis confirmed that loss of disc space height and angle of prosthesis insertion contributed independently to a model with a coefficient of determination of 0.39 (P<0.0001). Attempts to identify factors contributing to change in alignment have not shown any single factor to be wholly responsible. Although the prescribed surgical technique is relatively standardized, it seems likely that a number of surgical variables, particularly those leading to loss of disc space height and affecting annular tension are important.

Unilateral cervical facet dislocation: injury mechanism and biomechanical consequences.

Study Design. Human cadaveric cervical spines were subjected to nondestructive repeated-measures flexibility tests before, during, and after unilateral facet dislocation. Objectives. To assess the relative stability and kinematics of the spine in the normal condition, after unilateral facet lock without bony injury and after reducing (unlocking) the facet dislocation. Summary of Background Data. Experimental unilateral facet dislocation has been studied only when associated with extensive damage to disc, bone, or both. The relative stability of the normal, locked, and unlocked cervical spine has not been studied. Methods. Unilateral facet dislocation with minimal associated injury was created by slowly applying axial torque while specimens were bent laterally and flexed. Before and after injury, nondestructive torques were applied about each anatomic axis, while three-dimensional specimen motion was recorded stereophotogrammetrically. Results. Unilateral facet dislocation was created with a mean axial torque of 10.2 ± 2.7 Nm. After locking, range of motion, lax zone, and stiff zone were significantly reduced relative to normal (P < 0.05). After unlocking, the same parameters were significantly increased relative to normal. The position of the axis of rotation shifted when the facet was locked and the centrode elongated after the facet was unlocked. Conclusions. Unilateral facet dislocation without fracture can be created with moderate loads when axial torque is applied while the facet is distracted. The spine is stable while the articular masses are locked unilaterally; however, the motion segment becomes overtly unstable after the facet dislocation is reduced.

Hangman's fracture: a biomechanical comparison of stabilization techniques.

Study Design. In vitro biomechanical flexibility experiment studying 5 sequential conditions. Objective. To determine the biomechanical differences among 3 fixation techniques after a simulated hangman’s fracture. Summary of Background Data. Type II hangman’s fractures are often treated surgically with a C2–C3 anterior cervical discectomy, fusion, and plating. Other techniques include direct fixation with C2 pars interarticularis screws or posterior C2–C3 fixation connecting C2 pars screws to C3 lateral mass screws. Methods. Seven cadaveric specimens (Oc–C4) were tested intact, after a simulated hangman’s fracture, and after each fixation technique. Flexion, extension, lateral bending, and axial rotation were induced using nonconstraining torques while recording angular motions stereophotogrammetrically. Results. Direct screw fixation reduced motion an average of 61% ± 13% during lateral bending and axial rotation compared to the injured state (P < 0.007). However, instability remained during flexion and extension. Posterior C2–C3 rod fixation provided significantly greater rigidity than anterior plate fixation during lateral bending (P < 0.008) and axial rotation (P < 0.04). Conclusions. Direct fixation of the pars ineffectively limits flexion and extension after a Type II hangman’s fracture. If pars screw fixation can be achieved, posterior C2–C3 fixation more effectively stabilizes a hangman’s fracture than anterior cervical plating.

Anterior lumbar interbody fusion for treatment of failed back surgery syndrome: an outcome analysis.

OBJECTIVEAnterior lumbar interbody fusion (ALIF) has gained popularity for the treatment of degenerative disease of the lumbar spine. In this report, we present our experience with the ALIF procedure for treatment of failed back surgery syndrome (FBSS) in a noncontrolled prospective cohort. METHODSIn a 2-year period, we treated patients diagnosed with FBSS with ALIF. Clinical and radiological outcomes were recorded in a prospective, nonrandomized, longitudinal manner. Neurological, pain, and functional outcomes were measured preoperatively and 12 months after surgery. Operative data, perioperative complications, and radiological and clinical outcomes were recorded. RESULTSThirty-three patients with a preoperative diagnosis of FBSS, with degenerative disc disease (n = 17), postsurgical spondylolisthesis (n = 13), or pseudarthrosis (n = 3), underwent ALIF. Back pain, leg pain, and functional status improved significantly, by 76% (P < 0.01), 80% (P < 0.01), and 67% (P < 0.01), respectively. CONCLUSIONOn the basis of our results, we found ALIF to be a safe and effective procedure for the treatment of FBSS for selected patients.