Browse

You are looking at 1 - 10 of 29 items for

  • By Author: Theodore, Nicholas x
  • By Author: Sonntag, Volker K. H. x
Clear All
Full access

Scott D. Wait, M. Yashar S. Kalani, Andrew S. Little, Giac D. Consiglieri, Jeffrey S. Ross, Matthew R. Kucia, Volker K. H. Sonntag and Nicholas Theodore

Object

Patients who develop a lower-extremity neurological deficit after lumbar laminectomy present a diagnostic dilemma. In the setting of a neurological deficit, some surgeons use MRI to evaluate for symptomatic compression of the thecal sac. The authors conducted a prospective observational cohort study in patients undergoing open lumbar laminectomy for neurogenic claudication to document the MRI appearance of the postlaminectomy spine and to determine changes in thecal sac diameter caused by the accumulation of epidural fluid.

Methods

Eligible patients who were candidates for open lumbar laminectomy for neurogenic claudication at a single neurosurgical center between August 2007 and June 2009 were enrolled. Preoperative and postoperative MRI of the lumbar spine was performed on the same MRI scanner. Postoperative MRI studies were completed within 36 hours of surgery. Routine clinical and surgical data were collected at the preoperative visit, during surgery, and postoperatively. Images were interpreted for the signal characteristics of the epidural fluid and for thecal diameter (region of interest [ROI]) by 2 blinded neuroradiologists.

Results

Twenty-four patients (mean age 69.7 years, range 30–83 years) were enrolled, and 20 completed the study. Single-level laminectomy was performed in 6 patients, 2-level in 12, and 3-level in 2. Preoperative canal measurements (ROI) at the most stenotic level averaged 0.26 cm2 (range 0.0–0.46 cm2), and postoperative ROI at that same level averaged 0.95 cm2 (range 0.46–2.05 cm2). The increase in ROI averaged 0.69 cm2 (range 0.07–1.81 cm2). Seven patients (35%) had immediate postoperative weakness in at least 1 muscle group graded at 4+/5. The decline in examination was believed to be effort dependent and secondary to discomfort in the acute postoperative period. Those with weakness had smaller increases in ROI (0.51 cm2) than those with full strength (0.78 cm2, p = 0.1599), but none had evidence of worsened thecal compression. On the 1st postoperative day, 19 patients were at full strength and all patients were at full strength at their 15-day follow-up. The T1-weighted epidural fluid signal was isointense in 19 of the 20 patients. The T2-weighted epidural fluid signal was hyperintense in 9, isointense in 4, and hypointense in 7 patients.

Conclusions

Immediately after lumbar laminectomy, the appearance of the thecal sac on MRI can vary widely. In most patients the thecal sac diameter increases after laminectomy despite the presence of epidural blood. In this observational cohort, a reduction in thecal diameter caused by epidural fluid did not correlate with motor function. Results in the small subset of patients where the canal diameter decreased due to epidural fluid compression of the thecal sac raises the question of the utility of immediate postoperative MRI.

Restricted access

Nicholas Theodore, M. Yashar S. Kalani and Volker K. H. Sonntag

Restricted access

Udaya K. Kakarla, M. Yashar S. Kalani, Giriraj K. Sharma, Volker K. H. Sonntag and Nicholas Theodore

Object

Coccidioides immitis is a dimorphous fungus endemic in the southwestern US and northern Mexico. While its primary presentation is pulmonary, it can have devastating neurological sequelae.

Methods

The authors provide a retrospective review with long-term follow-up between 1986 and 2008 at a single institution.

Results

The authors identified 27 patients between 13 and 81 years old (mean 41.4 years) with spinal coccidioides who were treated surgically at the Barrow Neurological Institute between 1986 and 2008. There were 24 males (89%) and 3 females (11%). Eleven patients (41%) had cervical spine involvement, 15 (56%) had thoracic involvement, 7 (26%) had lumbar involvement, and 2 (7%) had sacral involvement. All 27 patients presented with localized or radiating pain. Nine patients (33%) had myelopathic symptoms at presentation, 5 (19%) had radiculopathy, 4 (15%) had fever, and 12 (44%) had progressive kyphosis. The disease was most frequently seen among African American patients (14 patients [52%]), followed by Caucasians (5 patients [19%]), Asians (3 patients [11%]), and Hispanics (3 patients [11%]). Ten patients (37%) required multiple operations at the same level. Follow-up was available in 19 patients (70%) (mean 9.8 months, range 1–39 months). Sixteen (84%) of these 19 patients improved from their preoperative baseline states, 1 (5%) was stable on examination, 1 patient's condition (5%) deteriorated compared with the preoperative examination, and 1 patient (5%) died in the postoperative period.

Conclusions

Although spinal involvement of coccidioidomycosis is relatively uncommon, a high index of suspicion and aggressive therapy are warranted to prevent devastating neurological injury, and lifelong antifungal therapy is often warranted.

Restricted access

Daniel D. Cavalcanti, Nikolay L. Martirosyan, Ketan Verma, Sam Safavi-Abbasi, Randall W. Porter, Nicholas Theodore, Volker K. H. Sonntag, Curtis A. Dickman and Robert F. Spetzler

Object

Schwannomas occupying the craniocervical junction (CCJ) are rare and usually originate from the jugular foramen, hypoglossal nerves, and C-1 and C-2 nerves. Although they may have different origins, they may share the same symptoms, surgical approaches, and complications. An extension of these lesions along the posterior fossa cisterns, foramina, and spinal canal—usually involving various cranial nerves (CNs) and the vertebral and cerebellar arteries—poses a surgical challenge. The primary goals of both surgical and radiosurgical management of schwannomas in the CCJ are the preservation and restoration of function of the lower CNs, and of hearing and facial nerve function. The origins of schwannomas in the CCJ and their clinical presentation, surgical management, adjuvant stereotactic radiosurgery, and outcomes in 36 patients treated at Barrow Neurological Institute (BNI) are presented.

Methods

Between 1989 and 2009, 36 patients (mean age 43.6 years, range 17–68 years) with craniocervical schwannomas underwent surgical resection at BNI. The records were reviewed retrospectively regarding clinical presentation, radiographic assessment, surgical approaches, adjuvant therapies, and follow-up outcomes.

Results

Headache or neck pain was present in 72.2% of patients. Cranial nerve impairments, mainly involving the vagus nerve, were present in 14 patients (38.9%). Motor deficits were found in 27.8% of the patients. Sixteen tumors were intra- and extradural, 15 were intradural, and 5 were extradural. Gross-total resection was achieved in 25 patients (69.4%). Adjunctive radiosurgery was used in the management of residual tumor in 8 patients; tumor control was ultimately obtained in all cases.

Conclusions

Surgical removal, which is the treatment of choice, is curative when schwannomas in the CCJ are excised completely. The far-lateral approach and its variations are our preferred approaches for managing these lesions. Most common complications involve deficits of the lower CNs, and their early recognition and rehabilitation are needed. Stereotactic radiosurgery, an important tool for the management of these tumors as adjuvant therapy, can help decrease morbidity rates.

Restricted access

Ali A. Baaj, Phillip M. Reyes, Ali S. Yaqoobi, Juan S. Uribe, Fernando L. Vale, Nicholas Theodore, Volker K. H. Sonntag and Neil R. Crawford

Object

Unstable fractures at the thoracolumbar junction often require extended, posterior, segmental pedicular fixation. Some surgeons have reported good clinical outcomes with short-segment constructs if additional pedicle screws are inserted at the fractured level. The goal of this study was to quantify the biomechanical advantage of the index-level screw in a fracture model.

Methods

Six human cadaveric T10–L4 specimens were tested. A 3-column injury at L-1 was simulated, and 4 posterior constructs were tested as follows: one-above-one-below (short construct) with/without index-level screws, and two-above-two-below (long construct) with/without index-level screws. Pure moments were applied quasistatically while 3D motion was measured optoelectronically. The range of motion (ROM) and lax zone across T12–L2 were measured during flexion, extension, left and right lateral bending, and left and right axial rotation.

Results

All constructs significantly reduced the ROM and lax zone in the fractured specimens. With or without index-level screws, the long-segment constructs provided better immobilization than the short-segment constructs during all loading modes. Adding an index-level screw to the short-segment construct significantly improved stability during flexion and lateral bending; there was no significant improvement in stability when an index-level screw was added to the long-segment construct. Overall, bilateral index-level screws decreased the ROM of the 1-level construct by 25% but decreased the ROM of the 2-level construct by only 3%.

Conclusions

In a fracture model, adding index-level pedicle screws to short-segment constructs improves stability, although stability remains less than that provided by long-segment constructs with or without index-level pedicle screws. Therefore, highly unstable fractures likely require extended, long-segment constructs for optimum stability.

Restricted access

Bruno C. R. Lazaro, Fatih Ersay Deniz, Leonardo B. C. Brasiliense, Phillip M. Reyes, Anna G. U. Sawa, Nicholas Theodore, Volker K. H. Sonntag and Neil R. Crawford

Object

Posterior screw-rod fixation for thoracic spine trauma usually involves fusion across long segments. Biomechanical data on screw-based short-segment fixation for thoracic fusion are lacking. The authors compared the effects of spanning short and long segments in the thoracic spine.

Methods

Seven human spine segments (5 segments from T-2 to T-8; 2 segments from T-3 to T-9) were prepared. Pure-moment loading of 6 Nm was applied to induce flexion, extension, lateral bending, and axial rotation while 3D motion was measured optoelectronically. Normal specimens were tested, and then a wedge fracture was created on the middle vertebra after cutting the posterior ligaments. Five conditions of instrumentation were tested, as follows: Step A, 4-level fixation plus cross-link; Step B, 2-level fixation; Step C, 2-level fixation plus cross-link; Step D, 2-level fixation plus screws at fracture site (index); and Step E, 2-level fixation plus index screws plus cross-link.

Results

Long-segment fixation restricted 2-level range of motion (ROM) during extension and lateral bending significantly better than the most rigid short-segment construct. Adding index screws in short-segment constructs significantly reduced ROM during flexion, lateral bending, and axial rotation (p < 0.03). A cross-link reduced axial rotation ROM (p = 0.001), not affecting other loading directions (p > 0.4).

Conclusions

Thoracic short-segment fixation provides significantly less stability than long-segment fixation for the injury studied. Adding a cross-link to short fixation improved stability only during axial rotation. Adding a screw at the fracture site improved short-segment stability by an average of 25%.

Restricted access

Ali A. Baaj, Juan S. Uribe, Tann A. Nichols, Nicholas Theodore, Neil R. Crawford, Volker K. H. Sonntag and Fernando L. Vale

Object

The objective of this work was to search a national health care database of patients diagnosed with cervical spine fractures in the US to analyze discharge, demographic, and hospital charge trends over a 10-year period.

Methods

Clinical data were derived from the Nationwide Inpatient Sample (NIS) for the years 1997 through 2006. The NIS is maintained by the Agency for Healthcare Research and Quality and represents a 20% random stratified sample of all discharges from nonfederal hospitals within the US. Patients with cervical spine fractures with and without spinal cord injury (SCI) were identified using the appropriate ICD-9-CM codes. The volume of discharges, length of stay (LOS), hospital charges, total national charges, discharge pattern, age, and sex were analyzed. National estimates were calculated using the HCUPnet tool.

Results

Approximately 200,000 hospitalizations were identified. In the non-SCI group, there was a 74% increase in hospitalizations and charges between 1997 and 2006, but LOS changed minimally. There was no appreciable change in the rate of in-hospital mortality (< 3%), but discharges home with home health care and to skilled rehabilitation or nursing facilities increased slightly. In the SCI group, hospitalizations and charges increased by 29 and 38%, respectively. There were no significant changes in LOS or discharge status in this group. Spinal cord injury was associated with increases in LOS, charges, and adverse outcomes compared with fractures without SCI. Total national charges associated with both groups combined exceeded $1.3 billion US in 2006.

Conclusions

During the studied period, increases in hospitalizations and charges were observed in both the SCI and non-SCI groups. The percentage increase was higher in the non-SCI group. Although SCI was associated with higher adverse outcomes, there were no significant improvements in immediate discharge status in either group during the 10 years analyzed.

Restricted access

Leonardo B. C. Brasiliense, Nicholas Theodore, Bruno C. R. Lazaro, Zafar A. Sayed, Fatih Ersay Deniz, Volker K. H. Sonntag and Neil R. Crawford

Object

The object of this study was to investigate the effects of iatrogenic pedicle perforations from screw misplacement on the mean pullout strength of thoracic pedicle screws.

Methods

Forty human thoracic vertebrae (T6–11) from human cadavers were studied. Before pedicle screws were inserted, the specimens were separated into 4 groups according to the type of screw used: 1) standard pedicle screw (no cortical perforation); 2) screw with medial cortical perforation; 3) screw with lateral cortical perforation; and 4) “airball” screw (a screw that completely missed the vertebral body). Consistency among the groups for bone mineral density, pedicle diameter, and screw insertion depth was evaluated. Finally, each screw was pulled out at a constant displacement rate of 10 mm/minute while ultimate strength was recorded.

Results

Compared with well-placed pedicle screws, medially misplaced screws had 8% greater mean pullout strength (p = 0.482) and laterally misplaced screws had 21% less mean pullout strength (p = 0.059). The difference in mean pullout strength between screws with medial and lateral cortical perforations was significant (p = 0.013). Airball screws had only 66% of the mean pullout strength of well-placed screws (p = 0.009) and had 16% lower mean pullout strength than laterally misplaced screws (p = 0.395).

Conclusions

This in vitro study showed a significant difference in mean pullout strength between medial and lateral misplaced pedicle screws. Moreover, airball screws were associated with a significant loss of pullout strength.

Restricted access

Eric M. Horn, Phillip M. Reyes, Seungwon Baek, Mehmet Senoglu, Nicholas Theodore, Volker K. H. Sonntag and Neil R. Crawford

Object

The small diameter of the pedicle can make C-7 pedicle screw insertion dangerous. Although transfacet screws have been studied biomechanically when used in pinning joints, they have not been well studied when used as part of a C7–T1 screw/rod construct. The authors therefore compared C7–T1 fixation using a C-7 transfacet screw/T-1 pedicle screw construct with a construct composed of pedicle screws at both levels.

Methods

Each rigid posterior screw/rod construct was placed in 7 human cadaveric C6–T2 specimens (14 total). Specimens were tested in normal condition, after 2-column instability, and once fixated. Nondestructive, nonconstraining pure moments (maximum 1.5 Nm) were applied to induce flexion, extension, lateral bending, and axial rotation while recording 3D motion optoelectronically. The entire construct was then loaded to failure by dorsal linear force.

Results

There was no significant difference in angular range of motion between the 2 instrumented groups during any loading mode (p > 0.11, nonpaired t-tests). Both constructs reduced motion to < 2° in any direction and allowed significantly less motion than in the normal condition. The C-7 facet screw/T-1 pedicle screw construct allowed a small but significantly greater lax zone than the pedicle screw/rod construct during lateral bending, and it failed under significantly less load than the pedicle screw/rod construct (p < 0.001).

Conclusions

When C-7 transfacet screws are connected to T-1 pedicle screws, they provide equivalent stability of constructs formed by pedicle screws at both levels. Although less resistant to failure, the transfacet screw construct should be a viable alternative in patients with healthy bone.

Restricted access

Nicholas C. Bambakidis, Eric M. Horn, Peter Nakaji, Nicholas Theodore, Elizabeth Bless, Tammy Dellovade, Chiyuan Ma, Xukui Wang, Mark C. Preul, Stephen W. Coons, Robert F. Spetzler and Volker K. H. Sonntag

Object

Sonic hedgehog (Shh) is a glycoprotein molecule that upregulates the transcription factor Gli1. The Shh protein plays a critical role in the proliferation of endogenous neural precursor cells when directly injected into the spinal cord after a spinal cord injury in adult rodents. Small-molecule agonists of the hedgehog (Hh) pathway were used in an attempt to reproduce these findings through intravenous administration.

Methods

The expression of Gli1 was measured in rat spinal cord after the intravenous administration of an Hh agonist. Ten adult rats received a moderate contusion and were treated with either an Hh agonist (10 mg/kg, intravenously) or vehicle (5 rodents per group) 1 hour and 4 days after injury. The rats were killed 5 days postinjury. Tissue samples were immediately placed in fixative. Samples were immunohistochemically stained for neural precursor cells, and these cells were counted.

Results

Systemic dosing with an Hh agonist significantly upregulated Gli1 expression in the spinal cord (p < 0.005). After spinal contusion, animals treated with the Hh agonist had significantly more nestin-positive neural precursor cells around the rim of the lesion cavity than in vehicle-treated controls (means ± SDs, 46.9 ± 12.9 vs 20.9 ± 8.3 cells/hpf, respectively, p < 0.005). There was no significant difference in the area of white matter injury between the groups.

Conclusions

An intravenous Hh agonist at doses that upregulate spinal cord Gli1 transcription also increases the population of neural precursor cells after spinal cord injury in adult rats. These data support previous findings based on injections of Shh protein directly into the spinal cord.