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Nicholas Theodore and Harold L. Rekate

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Nicholas C. Bambakidis, John Butler, Eric M. Horn, Xukui Wang, Mark C. Preul, Nicholas Theodore, Robert F. Spetzler and Volker K. H. Sonntag

✓ The development of an acute traumatic spinal cord injury (SCI) inevitably leads to a complex cascade of ischemia and inflammation that results in significant scar tissue formation. The development of such scar tissue provides a severe impediment to neural regeneration and healing with restoration of function. A multimodal approach to treatment is required because SCIs occur with differing levels of severity and over different lengths of time. To achieve significant breakthroughs in outcomes, such approaches must combine both neuroprotective and neuroregenerative treatments. Novel techniques modulating endogenous stem cells demonstrate great promise in promoting neuroregeneration and restoring function.

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Rogerio Rocha, Sam Safavi-Abbasi, Cassius Reis, Nicholas Theodore, Nicholas Bambakidis, Evandro De Oliveira, Volker K. H. Sonntag and Neil R. Crawford

Object

The authors measured relevant quantitative anatomical parameters to define safety zones for the placement of C-1 posterior screws.

Methods

Nineteen linear, two angular, and four surface parameters of 20 dried atlantal specimens were evaluated. The Optotrak 3020 system was used to define the working area. Ideal angles for screw positioning were measured using digital radiographs and a free image-processing program. Six silicone-injected cadaveric heads were dissected bilaterally to study related neurovascular anatomy.

The depth (range 5.2–9.4 mm, mean 7.2 ± 1.1 mm) and width (range 5.2–8.1 mm, mean 6.5 ± 0.9 mm) of the transverse foramen varied considerably among specimens. The mean posterior working area was 43.3 mm2. All specimens accommodated 3.5-mm-diameter screws, and 93% accepted 4-mm-diameter screws. In 10 specimens (50%), partial removal of the posterior arch was necessary to accommodate a 4-mm screw. The mean maximum angle of medialization was 16.7 ± 1.3°; the mean maximum superior angulation was 21.7 ± 4.7°.

Conclusions

The anatomical configuration of the atlas and vertebral artery (VA) varied considerably among the cadaveric specimens. The heights of the C-1 pedicle, posterior arch, and posterior lamina determine the posterior working area available for screw placement. The inferior insertion of the posterior arch may have to be drilled to increase this working area, but doing so risks injury to the VA. A dense venous plexus with multiple anastomoses may cover the screw entry site, potentially obscuring the operative view and increasing the risk of hemorrhage.

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Sam Safavi-Abbasi, Joseph M. Zabramski, Pushpa Deshmukh, Cassius V. Reis, Nicholas C. Bambakidis, Nicholas Theodore, Neil R. Crawford, Robert F. Spetzler and Mark C. Preul

Object

The authors quantitatively assessed the effects of balloon inflation as a model of tumor compression on the brainstem, cranial nerves, and clivus by measuring the working area, angle of attack, and brain shift associated with the retrosigmoid approach.

Methods

Six silicone-injected cadaveric heads were dissected bilaterally via the retrosigmoid approach. Quantitative data were generated, including key anatomical points on the skull base and brainstem. All parameters were measured before and after inflation of a balloon catheter (inflation volume 4.8 ml, diameter 20 mm) intended to mimic tumor compression.

Results

Balloon inflation significantly shifted (p < 0.001) the brainstem and cranial nerve foramina (mean [± standard deviation] displacement of upper brainstem, 10.2 ± 3.7 mm; trigeminal nerve exit, 6.99 ± 2.38 mm; facial nerve exit, 9.52 ± 4.13 mm; and lower brainstem, 13.63 ± 8.45 mm). The area of exposure at the petroclivus was significantly greater with balloon inflation than without (change, 316.26 ± 166.75 mm2; p < 0.0001). Before and after balloon inflation, there was no significant difference in the angles of attack at the origin of the trigeminal nerve (p > 0.5).

Conclusions

This study adds an experimental component to the emerging field of quantitative neurosurgical anatomy. Balloon inflation can be used to model the effects of a mass lesion. The tumor simulation created “natural” retraction and an opening toward the upper clivus. The findings may be helpful in selecting a surgical approach to increase the working space for resection of certain extraaxial tumors.

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Eric M. Horn, Nicholas Theodore, Rachid Assina, Robert F. Spetzler, Volker K. H. Sonntag and Mark C. Preul

Object

Venous stasis and intrathecal hypertension are believed to play a significant role in the hypoperfusion present in the spinal cord following injury. Lowering the intrathecal pressure via cerebrospinal fluid (CSF) drainage has been effective in treating spinal cord ischemia during aorta surgery. The purpose of the present study was to determine whether CSF drainage increases spinal cord perfusion and improves outcome after spinal injury in an animal model.

Methods

Anesthetized adult rabbits were subjected to a severe contusion spinal cord injury (SCI). Cerebrospinal fluid was then drained via a catheter to lower the intrathecal pressure by 10 mm Hg. Tissue perfusion was assessed at the site of injury, and values obtained before and after CSF drainage were compared. Two other cohorts of animals were subjected to SCI: 1 group subsequently underwent CSF drainage and the other did not. Results of histological analysis, motor evoked potential and motor function testing were compared between the 2 cohorts at 4 weeks postinjury.

Results

Cerebrospinal fluid drainage led to no significant improvement in spinal cord tissue perfusion. Four weeks after injury, the animals that underwent CSF drainage demonstrated significantly smaller areas of tissue damage at the injury site. There were no differences in motor evoked potentials or motor score outcomes at 4 weeks postinjury.

Conclusions

Cerebrospinal fluid drainage effectively lowers intrathecal pressure and decreases the amount of tissue damage in an animal model of spinal cord injury. Further studies are needed to determine whether different draining regimens can improve motor or electrophysiological outcomes.

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Owoicho Adogwa, Ricardo K. Carr, Katherine Kudyba, Isaac Karikari, Carlos A. Bagley, Ziya L. Gokaslan, Nicholas Theodore and Joseph S. Cheng

Object

Same-level recurrent lumbar stenosis, pseudarthrosis, and adjacent-segment disease (ASD) are potential complications that can occur after index lumbar spine surgery, leading to significant discomfort and radicular pain. While numerous studies have demonstrated excellent results following index lumbar spine surgery in elderly patients (age > 65 years), the effectiveness of revision lumbar surgery in this cohort remains unclear. The aim of this study was to assess the long-term effectiveness of revision lumbar decompression and fusion in the treatment of symptomatic pseudarthrosis, ASD, and same-level recurrent stenosis, using validated patient-reported outcomes.

Methods

After a review of the institutional database, 69 patients who had undergone revision neural decompression and instrumented fusion for ASD (28 patients), pseudarthrosis (17 patients), or same-level recurrent stenosis (24 patients) were included in this study. Baseline and 2-year scores on the visual analog scale for leg pain (VAS-LP), VAS for back pain (VAS-BP), Oswestry Disability Index (ODI), and Zung Self-Rating Depression Scale (SDS) as well as the time to narcotic independence, time to return to baseline activity level, health state utility (EQ-5D, the EuroQol-5D health survey), and physical and mental component summary scores of the 12-Item Short-Form Health Survey (SF-12 PCS and MCS) were assessed.

Results

Compared with the preoperative status, VAS-BP was significantly improved 2 years after surgery for ASD (mean ± standard deviation 9 ± 2 vs 4.01 ± 2.56, p = 0.001), pseudarthrosis (7.41 ± 1 vs 5.52 ± 3.08, p = 0.02), and same-level recurrent stenosis (7 ± 2.00 vs 5.00 ± 2.34, p = 0.003). The 2-year ODI was also significantly improved after surgery for ASD (29 ± 9 vs 23.10 ± 10.18, p = 0.001), pseudarthrosis (28.47 ± 5.85 vs 24.41 ± 7.75, p = 0.001), and same-level recurrent stenosis (30.83 ± 5.28 vs 26.29 ± 4.10, p = 0.003). The Zung SDS score and SF-12 MCS did not change appreciably after surgery in any of the cohorts, with an overall mean 2-year change of 1.01 ± 5.32 (p = 0.46) and 2.02 ± 9.25 (p = 0.22), respectively.

Conclusions

Data in this study suggest that revision lumbar decompression and extension of fusion for symptomatic pseudarthrosis, ASD, and same-level recurrent stenosis provides improvement in low-back pain, disability, and quality of life and should be considered a viable treatment option for elderly patients with persistent or recurrent back and radicular pain. Mental health symptoms may be more refractory to revision surgery.

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Eric M. Horn, Jonathan S. Hott, Randall W. Porter, Nicholas Theodore, Stephen M. Papadopoulos and Volker K. H. Sonntag

✓ Atlantoaxial stabilization has evolved from simple posterior wiring to transarticular screw fixation. In some patients, however, the course of the vertebral artery (VA) through the axis varies, and therefore transarticular screw placement is not always feasible. For these patients, the authors have developed a novel method of atlantoaxial stabilization that does not require axial screws. In this paper, they describe the use of this technique in the first 10 cases.

Ten consecutive patients underwent the combined C1–3 lateral mass–sublaminar axis cable fixation technique. The mean age of the patients was 62.6 years (range 23–84 years). There were six men and four women. Eight patients were treated after traumatic atlantoaxial instability developed (four had remote trauma and previous nonunion), whereas in the other two atlantoaxial instability was caused by arthritic degeneration. All had VA anatomy unsuitable to traditional transarticular screw fixation.

There were no intraoperative complications in any of the patients. Postoperative computed tomography studies demonstrated excellent screw positioning in each patient. Nine patients were treated postoperatively with the aid of a rigid cervical orthosis. The remaining patient was treated using a halo fixation device. One patient died of respiratory failure 2 months after surgery. Follow-up data (mean follow-up duration 13.1 months) were available for seven of the remaining nine patients and demonstrated a stable construct with fusion in each patient.

The authors present an effective alternative method in which C1–3 lateral mass screw fixation is used to treat patients with unfavorable anatomy for atlantoaxial transarticular screw fixation. In this series of 10 patients, the method was a safe and effective way to provide stabilization in these anatomically difficult patients.

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Nikolay L. Martirosyan, Jeanne S. Feuerstein, Nicholas Theodore, Daniel D. Cavalcanti, Robert F. Spetzler and Mark C. Preul

The authors present a review of spinal cord blood supply, discussing the anatomy of the vascular system and physiological aspects of blood flow regulation in normal and injured spinal cords. Unique anatomical functional properties of vessels and blood supply determine the susceptibility of the spinal cord to damage, especially ischemia. Spinal cord injury (SCI), for example, complicating thoracoabdominal aortic aneurysm repair is associated with ischemic trauma. The rate of this devastating complication has been decreased significantly by instituting physiological methods of protection. Traumatic SCI causes complex changes in spinal cord blood flow, which are closely related to the severity of injury. Manipulating physiological parameters such as mean arterial blood pressure and intrathecal pressure may be beneficial for patients with an SCI. Studying the physiopathological processes of the spinal cord under vascular compromise remains challenging because of its central role in almost all of the body's hemodynamic and neurofunctional processes.

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Corey T. Walker, M. Yashar S. Kalani, Mark E. Oppenlander, Jakub Godzik, Nikolay L. Martirosyan, Robert J. Standerfer and Nicholas Theodore

OBJECTIVE

The authors report a novel paradigm for resection of the disc or dural complex to treat giant calcified transdural herniated thoracic discs, and they describe a technique for the repair of dural defects. These herniated thoracic discs are uncommon, complicated lesions that often require a multidisciplinary team for effective treatment. The intradural component must be removed to effectively decompress the spinal cord. The opening of the friable dura mater, which frequently adheres to the extradural component of the disc, can result in large defects and difficult-to-manage CSF leaks.

METHODS

The authors performed a retrospective study of the technique and outcomes in patients with a transdural herniated disc treated at St. Joseph’s Hospital and Medical Center within a 4-year period between 2012 and 2015.

RESULTS

During the study period, 7 patients (mean age 56.1 years) presented to the department of neurosurgery with clinical symptoms consistent with myeloradiculopathy. In all cases, 2-level corpectomies of the involved levels were combined with circumferential resection of the dura and complete decompression of the spinal cord. The dural defect was repaired with an onlay dural patch, and a large piece of AlloDerm (LifeCell Corp) graft was sewn to close the pleural defect. Every patient had a perioperative lumbar drain placed for CSF diversion. No patient suffered neurological decline related to the surgery, and 3 patients experienced clinically significant improvement in function. Two patients developed an early postoperative CSF leak that required operative revision to oversew the defects.

CONCLUSIONS

This novel technique for decompression of the spinal cord by dural resection for the removal of giant calcified transdural herniated thoracic discs is safe and results in excellent decompression of the spinal cord. The technique becomes necessary when primary repair of the dura is not possible, and it can be used in cases in which the resection of pathology includes the dura.

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Corinna C. Zygourakis, A. Karim Ahmed, Samuel Kalb, Alex M. Zhu, Ali Bydon, Neil R. Crawford and Nicholas Theodore

The Excelsius GPS (Globus Medical, Inc.) was approved by the FDA in 2017. This novel robot allows for real-time intraoperative imaging, registration, and direct screw insertion through a rigid external arm—without the need for interspinous clamps or K-wires. The authors present one of the first operative cases utilizing the Excelsius GPS robotic system in spinal surgery. A 75-year-old man presented with severe lower back pain and left leg radiculopathy. He had previously undergone 3 decompressive surgeries from L3 to L5, with evidence of instability and loss of sagittal balance. Robotic assistance was utilized to perform a revision decompression with instrumented fusion from L3 to S1. The usage of robotic assistance in spinal surgery may be an invaluable resource in minimally invasive cases, minimizing the need for fluoroscopy, or in those with abnormal anatomical landmarks.

The video can be found here: https://youtu.be/yVI-sJWf9Iw.