Heterotopic bone formation within the spinal canal is a known complication of bone morphogenetic protein–2 (BMP-2) and presents a clinical and surgical challenge. Imaging modalities are routinely used for operative planning in this setting. Here, the authors present the case of a 59-year-old woman with cauda equina syndrome following intraoperative BMP-2 administration. Plain film myelographic studies showed a region of severe stenosis that was underappreciated on CT myelography due to a heterotopic bony lesion mimicking the dorsal aspect of a circumferentially patent thecal sac. When evaluating spinal stenosis under these circumstances, it is important to carefully consider plain myelographic images in addition to postmyelography CT images as the latter may underestimate the true degree of stenosis due to the potentially similar radiographic appearances of evolving BMP-2–induced heterotopic bone and intrathecal contrast. Alternatively, comparison of sequentially acquired noncontrast CT scans with CT myelographic images may also assist in distinguishing BMP-2–induced heterotopic bony lesions from the thecal sac. Further studies are needed to elucidate the roles of the available imaging techniques in this setting and to characterize the connection between the radiographic and histological appearances of BMP-2–induced heterotopic bone.
Timothy Chryssikos, Kenneth M. Crandall and Charles A. Sansur
W. Jeff Elias, Charles A. Sansur and Robert C. Frysinger
The authors analyzed deep brain stimulation electrode trajectories on MR images to identify risks of cerebrovascular complications associated with the number of electrode insertions, traversal of a sulcus, and penetration of the ventricle.
Pre- and postoperative MR volumes were fused to determine the proximity of electrodes to a sulcus or ventricle and whether there were cortical, subcortical, or intraventricular complications. Complications were further classified as hemorrhagic or nonhemorrhagic and symptomatic or asymptomatic. The authors examined 258 electrode implantation for deep brain stimulation. There were 4 symptomatic events (1.6% incidence): 3 hemorrhagic and 1 nonhemorrhagic, all within the cortex. Asymptomatic events included cortical hemorrhage in 1 patient, nonhemorrhagic cortical changes in 6, pallidal hemorrhage in 1, thalamic infarction in 1, and intraventricular hemorrhage (IVH) in 5 patients.
Proximity to a sulcus was a significant risk factor for hemorrhagic and nonhemorrhagic cortical complications (p = 0.001). There was a complication rate of 10.1% within the trajectories penetrating or adjacent to a sulcus, and a 0.7% rate with trajectories clearly positioned within the gyrus. Asymptomatic IVH was observed in 5% of ventricular penetrations. A history of hypertension was a risk factor for cortical hemorrhage (p = 0.019), but not for cortical ischemic/edematous events (p = 0.605). The number of electrode penetrations did not differ between patients with and without complications (p = 0.868), and the sequence of electrode insertions was not a risk factor in bilateral surgeries.
Symptomatic cortical complications occur when electrodes traverse close to a sulcus. Asymptomatic IVH occurs infrequently with ventricular penetration. Despite intraoperative efforts to avoid cortical sulci, a higher than expected incidence of electrode proximity to the sulci was identified on careful postoperative trajectory analysis. This finding emphasizes the importance of assiduously planning trajectories and reviewing cases with thorough MR analysis.
Charles A. Sansur, John D. Heiss, Hetty L. DeVroom, Eric Eskioglu, Robert Ennis and Edward H. Oldfield
Object. The aim of this study was to evaluate the pathophysiology underlying headache associated with cough in patients with Chiari I tonsillar abnormality. The authors hypothesized that peak intrathecal pressure during coughing is higher in patients with headache aggravated by cough than in patients without or in healthy volunteers. In addition, the authors evaluated the use of intrathecal pressure during cough as a means of assessing obstruction to the free flow of cerebrospinal fluid (CSF) at the craniocervical junction.
Methods. Twenty-six adult patients with Chiari I malformation and syringomyelia, four adult patients with Chiari I malformation without syringomyelia, and 15 healthy volunteers were prospectively studied. Testing before surgery included the following: 1) clinical evaluation for the presence of headache associated with cough; and 2) evaluation of lumbar subarachnoid pressure at rest, during three to five coughs, while performing the Valsalva maneuver, during jugular compression, and after removal of CSF. Patients underwent suboccipital craniectomy, C-1 laminectomy, and duraplasty. Testing was repeated 6 months after surgery.
Conclusions. Peak intrathecal pressures during cough and at baseline were elevated in patients with headache associated with cough compared with either patients without headache or healthy volunteers. After surgery, intrathecal pressures during cough were significantly lower than preoperative values and headache aggravated by cough was resolved partially or completely. Headache linked to coughing in patients with Chiari I malformation is associated with sudden increased intrathecal pressure caused by obstruction to the free flow of CSF in the subarachnoid space.
Narlin Beaty, Justin Slavin, Cara Diaz, Kyle Zeleznick, David Ibrahimi and Charles A. Sansur
Gunshot wounds (GSWs) to the cervical spine have been examined in a limited number of case series, and operative management of this traumatic disease has been sparsely discussed. The current literature supports and the authors hypothesize that patients without neurological deficit need neither surgical fusion nor decompression. Patients with GSWs and neurological deficits, however, pose a greater management challenge. The authors have compiled the experience of the R Adams Cowley Shock Trauma Center in Baltimore, Maryland, over the past 12 years, creating the largest series of such injuries, with a total number of 40 civilian patients needing neurosurgical evaluation. The current analysis examines presenting bone injury, surgical indication, presenting neurological examination, and neurological outcome. In this study, the authors characterize the incidence, severity, and recovery potential of cervical GSWs. The rate of unstable fractures requiring surgical intervention is documented. A detailed discussion of surgical indications with a treatment algorithm for cervical instability is offered.
A total of 144 cervical GSWs were retrospectively reviewed. Of these injuries, 40 had documented neurological deficits. No neurosurgical consultation was requested for patients without deficit. Epidemiological and clinical information was collected on patients with neurological deficit, including age, sex, timing, indication, type of surgery, initial examination after resuscitation, follow-up examination, and imaging data.
Twenty-eight patients (70%) presented with complete neurological deficits and 12 patients (30%) presented with incomplete injuries. Fourteen (35%) of the 40 patients underwent neurosurgical intervention. Twelve patients (30%) required intervention for cervical instability. Seven patients required internal fixation involving 4 anterior fusions, 2 posterior fusions, and 1 combined approach. Five patients were managed with halo immobilization. Two patients underwent decompression alone for neurological deterioration and persistent compressive injury, both of whom experienced marked neurological recovery. Follow-up was obtained in 92% of cases. Three patients undergoing stabilization converted at least 1 American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade and the remaining operative cases experienced small ASIA motor score improvement. Eighteen patients underwent inpatient MRI. No patient suffered complications or neurological deterioration related to retained metal. Three of 28 patients presenting with AIS Grade A improved to Grade B. For those 12 patients with incomplete injury, 1 improved from AIS Grade C to D, and 3 improved from Grade D to E.
Spinal cord injury from GSWs often results in severe neurological deficits. In this series, 30% of these patients with deficits required intervention for instability. This is the first series that thoroughly documents AIS improvement in this patient population. Adherence to the proposed treatment algorithm may optimize neurological outcome and spine stability.
Andrei F. Joaquim, Catherine C. Shaffrey, Charles A. Sansur and Christopher I. Shaffrey
The authors report a case of man-in-the-barrel (MIB) syndrome occurring after an extensive revision involving thoracoilium instrumentation and fusion for iatrogenic and degenerative scoliosis, progressive kyphosis, and sagittal imbalance. Isolated brachial diplegia is a rare neurological finding often attributed to cerebral ischemia. It has not been previously reported in patients undergoing complex spine surgery. This 70-year-old woman, who had previously undergone T11–S1 fusion for lumbar stenosis and scoliosis, presented with increased difficulty walking and with back pain. She had junctional kyphosis and L5–S1 pseudarthrosis and required revision fusion extending from T-3 to the ilium. In the early postoperative period, she experienced a 30-minute episode of substantial hypotension. She developed delirium and isolated brachial diplegia, consistent with MIB syndrome. Multiple studies were performed to assess the origin of this brachial diplegia. There was no definitive radiological evidence of any causative lesion. After a few days, her cognitive function returned to normal and she regained the ability to move her arms. After several weeks of rehabilitation, she recovered completely. Man-in-the-barrel syndrome is a rare neurological entity. It can result from various mechanisms but most commonly seems to be related to ischemia and is potentially reversible.
Akil P. Patel, Michael T. Koltz, Charles A. Sansur, Mangla Gulati and D. Kojo Hamilton
Patients requiring neurosurgical intervention are known to be at increased risk for deep vein thrombosis (DVT) and attendant morbidity and mortality. Pulmonary embolism (PE) is the most catastrophic sequela of DVT and is the direct cause of death in 16% of all in-hospital mortalities. Protocols for DVT screening and early detection, as well as treatment paradigms to prevent PE in the acute postoperative period, are needed in neurosurgery. The authors analyzed the effectiveness of weekly lower-extremity venous duplex ultrasonography (LEVDU) in patients requiring surgical intervention for cranial or spinal pathology for detection of DVT and prevention of PE.
Data obtained in 1277 consecutive patients admitted to a major tertiary care center requiring neurosurgical intervention were retrospectively reviewed. All patients underwent admission (within 1 week of neurosurgical intervention) LEVDU as well as weekly LEVDU surveillance if the initial study was normal. Additional LEVDU was ordered in any patient in whom DVT was suspected on daily clinical physical examination or in patients in whom chest CT angiography confirmed a pulmonary embolus. An electronic database was created and statistical analyses performed.
The overall incidence of acute DVT was 2.8% (36 patients). Of these cases of DVT, a statistically significant greater number (86%) were discovered on admission (within 1–7 days after admission) screening LEVDU (p < 0.05), whereas fewer were documented 8–14 days after admission (2.8%) or after 14 days (11.2%) postadmission. Additionally, for acute DVT detection in the present population, there were no underlying statistically significant risk factors regarding baseline physical examination, age, ambulatory status, or type of surgery.
The overall incidence of acute symptomatic PE was 0.3% and the mortality rate was 0%.
Performed within 1 week of admission in patients who will undergo neurosurgical intervention, LEVDU is effective in screening for acute DVT and initiating treatment to prevent PE, thereby decreasing the overall mortality rate. Routine LEVDU beyond this time point may not be needed to detect DVT and prevent PE unless a change in the patient's physical examination status is detected.
D. Kojo Hamilton, Justin S. Smith, Charles A. Sansur, Aaron S. Dumont and Christopher I. Shaffrey
The originally described technique of atlantoaxial stabilization using C-1 lateral mass and C-2 pars screws includes a C-2 neurectomy to provide adequate hemostasis and visualization for screw placement, enable adequate joint decortication and arthrodesis, and prevent new-onset postoperative C-2 neuralgia. However, inclusion of a C-2 neurectomy for this procedure remains controversial, likely due in part to a lack of studies that have specifically addressed whether it affects patient outcome. The authors' objective was to assess the surgical and clinical impact of routine C-2 neurectomy performed with C1–2 segmental instrumented arthrodesis in a consecutive series of elderly patients with C1–2 instability.
Forty-four consecutive patients (mean age 71 years) underwent C1–2 instrumented fusion, including C-1 lateral mass screw insertion. Bilateral C-2 neurectomies were performed. Standardized clinical assessments were performed both pre- and postoperatively. Numbness or discomfort in a C-2 distribution was documented at follow-up. Fusion was assessed using the Lenke fusion grade.
Among all 44 patients, mean blood loss was 200 ml (range 100–350 ml) and mean operative time was 129 minutes (range 87–240 minutes). There were no intraoperative complications, and no patients reported new postoperative onset or worsening of C-2 neuralgia postoperatively. Outcomes for the 30 patients with a minimum 13-month follow-up (range 13–72 months) were assessed. At a mean follow-up of 36 months, Nurick grade and pain numeric rating scale scores improved from 3.7 to 1.0 (p < 0.001) and 9.4 to 0.6 (p < 0.001), respectively. The mean postoperative Neck Disability Index score was 7.3%. The fusion rate was 97%, and the patient satisfaction rate was 93%. All 24 patients with preoperative occipital neuralgia reported relief. Seventeen patients noticed C-2 distribution numbness only during examination in the clinic, and 2 patients reported C-2 numbness, but it did not affect their daily function.
In this series of C1–2 instrumented arthrodesis in elderly patients, excellent fusion rates were achieved, and patient satisfaction was not negatively affected by C-2 neurectomy. In the authors' experience, C-2 neurectomy enhanced surgical exposure of the C1–2 joint, thereby facilitating hemostasis, placement of instrumentation, and decortication of the joint space for arthrodesis. Importantly, with C-2 neurectomy in the present series, no cases of new onset postoperative C-2 neuralgia occurred, in contrast to a growing number of reports in the literature documenting new-onset C-2 neuralgia without C-2 neurectomy. On the contrary, 80% of patients in the present series had preoperative occipital neuralgia and in all of these patients this neuralgia was relieved following C1–2 instrumented arthrodesis with C-2 neurectomy.
Charles A. Sansur, Kai-Ming G. Fu, Rod J. Oskouian Jr., Jay Jagannathan, Charles Kuntz iv and Christopher I. Shaffrey
✓ Ankylosing spondylitis (AS) is an inflammatory rheumatic disease whose primary effect is on the axial skeleton, causing sagittal-plane deformity at both the thoracolumbar and cervicothoracic junctions. In the present review article the authors discuss current concepts in the preoperative planning of patients with AS. The authors also review current techniques used to treat sagittal-plane deformity, focusing on pedicle subtraction osteotomy at the thoracolumbar junction, as well as cervical extension osteotomy at the cervicothoracic junction.
Jay Jagannathan, Christopher I. Shaffrey, Rod J. Oskouian, Aaron S. Dumont, Christian Herrold, Charles A. Sansur and John A. Jane Sr.
Although the clinical outcomes following anterior cervical discectomy and fusion (ACDF) surgery are generally good, 2 major complications are graft migration and nonunion. These complications have led some to advocate rigid internal fixation and/or cervical immobilization postoperatively. This paper examines a single-surgeon experience with single-level ACDF without use of plates or hard collars in patients with degenerative spondylosis in whom allograft was used as the fusion material.
The authors conducted a retrospective review of a prospective database of (Cloward-type) ACDF operations performed by the senior author (J.A.J.) between July 1996 and June 2005. Radiographic follow-up included static and flexion/extension radiographs obtained to assess fusion, focal and segmental kyphosis, and change in disc space height. At most recent follow-up, the patients' condition was evaluated by an independent physician examiner. The Odom criteria and Neck Disability Index (NDI) were used to assess outcome.
One hundred seventy patients underwent single-level ACDF for degenerative pathology during the study period. Their most common presenting symptoms were pain, weakness, and radiculopathy; 88% of patients noted ≥ 2 neurological complaints. The mean hospital stay was 1.76 days (range 0–36 days), and 3 patients (2%) had major immediate postoperative complications requiring reoperation. The mean duration of follow-up was 22 months (range 12–124 months). Radiographic evidence of fusion was present in 160 patients (94%). Seven patients (4%) showed radiographic evidence of pseudarthrosis, and graft migration was seen in 3 patients (2%). All patients had increases in focal kyphosis at the operated level on postoperative radiographs (mean −7.4°), although segmental alignment was preserved in 133 patients (78%). Mean change in disc space height was 36.5% (range 28–53%). At most recent clinical follow-up, 122 patients (72%) had no complaints referable to cervical disease and were able to carry out their activities of daily living without impairment. The mean postoperative NDI score was 3.2 (median 3, range 0–31).
Single-level ACDF without intraoperative plate placement or the use of a postoperative collar is an effective treatment for cervical spondylosis. Although there is evidence of focal kyphosis and loss of disc space height, radiographic evidence of fusion is comparable to that attained with plate fixation, and the rate of clinical improvement is high.
Christopher M. Maulucci, Charles A. Sansur, Vaneet Singh, Alexandra Cholewczynski, Snehal S. Shetye, Kirk McGilvray and Christian M. Puttlitz
Nerve root decompression to relieve pain and radiculopathy remains one of the main goals of fusion-promoting procedures in the subaxial cervical spine. The use of allograft facet spacers has been suggested as a potential alternative for performing foraminotomies to increase the space available for the cervical nerve roots while providing segmental stiffening. Therefore, the goal of this cadaveric biomechanical study was to determine the acute changes in kinetics and foraminal area after the insertion of cortical bone facet spacers into the subaxial cervical spine.
Allograft spacers (2 mm in height) were placed bilaterally into cadaveric cervical spine specimens (C2-T1, age of donors 57.5 ± 9.5 years, n = 7) at 1 (C4–5) and 3 (C3–6) levels with and without laminectomies and posterior lateral mass screw fixation. Standard stereophotogrammetry under pure moment loading was used to assess spinal kinetics. In addition, the authors performed 3D principal component analysis of CT scans to determine changes in foraminal cross-sectional area (FCSA) available for the spinal nerve roots.
Generally, the introduction of 2-mm-height facet spacers to the cervical spine produced mild, statistically insignificant reductions in motion with particular exceptions at the levels of implantation. No significant adjacent-level motion effects in any bending plane were observed. The addition of the posterior instrumentation (PI) to the intact spines resulted in statistically significant reductions in motion at all cervical levels and bending planes. The same kinetic results were obtained when PI was added to spines that also had facet spacers at 3 levels and spines that had been destabilized by en bloc laminectomy. The addition of 2-mm facet spacers at C3–4, C4–5, and C5–6 did produce statistically significant increases in FCSA at those levels.
The addition of allograft cervical facet spacers should be considered a potential option to accomplish indirect foraminal decompression as measured in this cadaveric biomechanical study. However, 2-mm spacers without supplemental instrumentation do not provide significantly increased spinal segmental stability.