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S. Harrison Farber, David J. Mauler, Soumya Sagar, Mark A. Pacult, Corey T. Walker, Michael A. Bohl, Laura A. Snyder, Kristina M. Chapple, Volker K. H. Sonntag, Juan S. Uribe, Jay D. Turner, Steve W. Chang, and U. Kumar Kakarla

OBJECTIVE

Anterior cervical discectomy and fusion (ACDF) is a common and robust procedure performed on the cervical spine. Literature on ACDF for 4 or more segments is sparse. Increasing the number of operative levels increases surgical complexity, tissue retraction, and risks of complications, particularly dysphagia. The overall risks of these complications and rates of dysphagia are not well studied for surgery on 4 or more segments. In this study, the authors evaluated their institution’s perioperative experience with 4- and 5-level ACDFs.

METHODS

The authors retrospectively reviewed patients who underwent 4- or 5-level ACDF at their institution over a 6-year period (May 2013–May 2019). Patient demographics, perioperative complications, readmission rates, and swallowing outcomes were recorded. Outcomes were analyzed with a multivariate linear regression.

RESULTS

A total of 174 patients were included (167 had 4-level and 7 had 5-level ACDFs). The average age was 60.6 years, and 54.0% of patients (n = 94) were men. A corpectomy was performed in 12.6% of patients (n = 22). After surgery, 56.9% of patients (n = 99) experienced dysphagia. The percentage of patients with dysphagia decreased to 22.8% (37/162) at 30 days, 12.9% (17/132) at 90 days, and 6.3% (5/79) and 2.8% (1/36) at 1 and 2 years, respectively. Dysphagia was more likely at 90 days postoperatively in patients with gastroesophageal reflux (OR 4.4 [95% CI 1.5–12.8], p = 0.008), and the mean (± SD) lordosis change was greater in patients with dysphagia than those without at 90 days (19.8° ± 13.3° vs 9.1° ± 10.2°, p = 0.003). Dysphagia occurrence did not differ with operative implants, including graft and interbody type. The mean length of time to solid food intake was 2.4 ± 2.1 days. Patients treated with dexamethasone were more likely to achieve solid food intake prior to discharge (OR 4.0 [95% CI 1.5–10.6], p = 0.004). Postsurgery, 5.2% of patients (n = 9) required a feeding tube due to severe approach-related dysphagia. Other perioperative complication rates were uniformly low. Overall, 8.6% of patients (n = 15) returned to the emergency department within 30 days and 2.9% (n = 5) required readmission, whereas 1.1% (n = 2) required unplanned return to surgery within 30 days.

CONCLUSIONS

This is the largest series of patients undergoing 4- and 5-level ACDFs reported to date. This procedure was performed safely with minimal intraoperative complications. More than half of the patients experienced in-hospital dysphagia, which increased their overall length of stay, but dysphagia decreased over time.

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History and advances in spinal neurosurgery

JNSPG 75th Anniversary Invited Review Article

Corey T. Walker, U. Kumar Kakarla, Steve W. Chang, and Volker K. H. Sonntag

Insight into the historic contributions made to modern-day spine surgery provides context for understanding the monumental accomplishments comprising current techniques, technology, and clinical success. Only during the last century did surgical growth occur in the treatment of spinal disorders. With that growth came a renaissance of innovation, particularly with the evolution of spinal instrumentation and fixation techniques. In this article, the authors capture some of the key milestones that have led to the field of spine surgery today, with an emphasis on the historical advances related to instrumentation, navigation, minimally invasive surgery, robotics, and neurosurgical training.

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Paul A. Gardner, Juan C. Fernandez-Miranda, Carl H. Snyderman, and Eric W. Wang

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George A. C. Mendes, Curtis A. Dickman, Nestor G. Rodriguez-Martinez, Samuel Kalb, Neil R. Crawford, Volker K. H. Sonntag, Mark C. Preul, and Andrew S. Little

OBJECT

The primary disadvantage of the posterior cervical approach for atlantoaxial stabilization after odontoidectomy is that it is conducted as a second-stage procedure. The goal of the current study is to assess the surgical feasibility and biomechanical performance of an endoscopic endonasal surgical technique for C1–2 fixation that may eliminate the need for posterior fixation after odontoidectomy.

METHODS

The first step of the study was to perform endoscopic endonasal anatomical dissections of the craniovertebral junction in 10 silicone-injected fixed cadaveric heads to identify relevant anatomical landmarks. The second step was to perform a quantitative analysis using customized software in 10 reconstructed adult cervical spine CT scans to identify the optimal screw entry point and trajectory. The third step was biomechanical flexibility testing of the construct and comparison with the posterior C1–2 transarticular fixation in 14 human cadaveric specimens.

RESULTS

Adequate surgical exposure and identification of the key anatomical landmarks, such as C1–2 lateral masses, the C-1 anterior arch, and the odontoid process, were provided by the endonasal endoscopic approach in all specimens. Radiological analysis of anatomical detail suggested that the optimal screw entry point was on the anterior aspect of the C-1 lateral mass near the midpoint, and the screw trajectory was inferiorly and slightly laterally directed. The custommade angled instrumentation was crucial for screw placement. Biomechanical analysis suggested that anterior C1–2 fixation compared favorably to posterior fixation by limiting flexion-extension, axial rotation, and lateral bending (p > 0.3).

CONCLUSIONS

This is the first study that demonstrates the feasibility of an endoscopic endonasal technique for C1–2 fusion. This novel technique may have clinical utility by eliminating the need for a second-stage posterior fixation operation in certain patients undergoing odontoidectomy.

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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.

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

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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.

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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.

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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.

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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%.