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Matthew M. Robbins, Alexander R. Vaccaro, and Luke Madigan

The use of bioabsorbable implants in spine surgery is expanding at a rapid pace. These implants are mimicking the roles of traditional metallic devices and are demonstrating similar efficacy in terms of maintaining stability and acting as carriers for grafting substances. Biomechanical studies have demonstrated their ability to stabilize effectively a degenerative cervical and lumbar motion segment. In numerous animal models, researchers have illustrated the ability of bioabsorbable implants to function satisfactorily as an interbody spacer and to achieve satisfactory bone fusion. Investigators have explored various opportunities for these implants to replace their metallic counterparts in clinical studies conducted in humans. The gradual resorption of these implants appears effectively to transfer gradual loads to the grafting substances promoting the biological mechanisms of fusion.

Novel uses of bioabsorbable technology are constantly evolving. Their future as a carrier of biological agents such as bone morphogenetic proteins and bone graft extenders, their radiolucency, and their eventual resorption make them an ideal implant for use in spinal degenerative disease.

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Matthew T. Neal, Randall J. Hlubek, Alexander E. Ropper, and U. Kumar Kakarla

When a dural defect is encountered during spine surgery, the dura mater must be reconstituted to minimize the occurrence of minor or major life-threatening sequelae. The neurosurgical literature lacks strategies for managing large dural defects encountered during surgery. The authors describe a 24-year-old man who developed cauda equina syndrome secondary to altered CSF flow in a large thoracolumbar arachnoid cyst. Surgical decompression and fenestration of the arachnoid cyst were performed, and the large dural defect was treated using a multilayer closure with collagen matrix, titanium mesh, and methylmethacrylate. At his 24-month postoperative follow-up, the patient had recovered full strength in his legs, and his sensory deficits and sexual dysfunction had resolved. His incision had healed well, and there were no signs of pseudomeningocele. He had no additional positional headaches. The defect was managed effectively with this technique. Although this technique is not a first-line strategy for dural closure in the spine, it can be considered in challenging cases when large dural defects are not amenable to traditional closure techniques.

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Matthew F. Philips, Steven B. Schwartz, Alexander D. Soutter, and Leslie N. Sutton

✓ Children with shunted hydrocephalus often have a myriad of other medical conditions. When these concomitant problems involve the pleura, peritoneum, and/or the venous system, placement of the distal catheter may prove to be problematic. This report presents preliminary results in three hydrocephalic children following ventriculofemoroatrial shunt placement. The peritoneal and pleural cavities in each of these children were compromised and there was no vascular access into the superior vena cava due to intercurrent disease. An alternative technique for ventriculoperitoneal shunt placement was performed via the femoral vein. Fluoroscopic guidance was used to confirm the intraatrial position of the distal end of the shunt catheter. Follow-up review to date shows no complications. This newly described technique provides a feasible alternative to distal shunt catheter placement in patients in whom more traditional sites are unavailable.

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Zachary N. Litvack, Matthew A. Hunt, Jason S. Weinstein, and G. Alexander West

✓ In this case report, the authors describe a 33-year-old man who presented with headache due to the presence of 12 nail-gun nails impacted in his cranium and cerebral parenchyma. The authors also review the relevant literature regarding penetrating brain injury.

The patient's physical examination revealed a Glasgow Coma Scale score of 15 and impairment of abduction of the right eye and abduction of the jaw producing dysarthria; the remaining results of the neurological examination were normal. Both x-ray films and computerized tomography (CT) scans of the head revealed the presence of 12 nails, the majority of which were located intracranially. A scattering artifact limited the ability of CT scanning to demonstrate any intracranial hemorrhage. Angiography did not demonstrate any evidence of traumatic vascular injury. After general anesthesia had been induced in the patient, the nails were removed in the operating room. Following removal of the final nail, a small left temporal craniotomy was performed to control hemorrhage from a tear in the left middle meningeal artery. Despite the development of a postoperative insular hematoma, the patient was discharged home with minimal deficits.

This patient is the only known survivor of the largest number of foreign objects (12) to penetrate the skull intentionally. Overall, self-inflicted nail-gun injuries are less common than accidental discharges. A review of the literature, however, suggests that for penetrating brain injury, self-infliction is the more common mechanism. For those patients who survive such an injury, clinical decision making must focus on preventing further cortical or vascular damage. A rational management strategy should permit these patients to be discharged with no additional injury.

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Alexander R. Vaccaro, Matthew M. Robbins, Luke Madigan, Todd J. Albert, William Smith, and Alan S. Hilibrand

Object

In this pilot study the authors assessed the efficacy of bioabsorbable interbody spacers in the treatment of cervical degenerative disease. Metallic cages or interbody spacers have been widely used in the treatment of degenerative and traumatic cervical disease. Bioabsorbable technology has been used to develop a resorbable cage that can eliminate the complications and drawbacks seen with the use of traditional metallic implants. In general clinical practice bioabsorbable implants have shown the ability to degrade safely while demonstrating optimal imaging characteristics as a result of their radiolucency, and these devices eliminate stress shielding by their gradual dissolution.

Methods

This study is a retrospective evaluation of charts and x-ray films obtained in the first eight patients who underwent an anterior cervical decompression and fusion procedure with placement of a bioabsorbable interbody spacer and anterior cervical plate. All patients were treated in one surgeon's practice and had a minimum follow-up period of at least 6 months. At a follow-up interval of approximately 7 months, five patients exhibited an excellent result and three had a good result; no patient was noted to have a satisfactory or poor outcome according to the Odom criteria at their most recent follow-up visit. Seventeen (94%) of 18 grafted levels appeared to be solidly fused. One patient experienced a perisurgical complication consisting of a symptomatic hematoma, which was successfully drained.

Conclusions

Bioabsorbable interbody spacers appear to be a safe and effective interbody implant in terms of clinical outcome and radiographically confirmed healing.

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Michael Anthony Ciliberto, David Limbrick, Alexander Powers, Jeffrey B. Titus, Rebecca Munro, and Matthew D. Smyth

Object

Intractable epilepsy is a significant burden on families and on the cognitive development and quality of life (QOL) of patients. Periinsular hemispherotomy (PIH) for medically intractable epilepsy can benefit patients who qualify for this procedure. The ideal hemispherotomy candidate has ipsilateral ictal and interictal epileptiform activity, unilateral MR imaging abnormalities, contralateral hemiplegia, and a normal contralateral hemisphere. However, certain patients present with a mixed picture of bilateral electroencephalography (EEG) findings and severe intractable epilepsy, prompting consideration of a more aggressive treatment approach. This report introduces the possibility of surgery for patients who normally would not meet criteria for this treatment modality.

Methods

In this retrospective chart review, the authors report on 7 patients with bilateral seizure onset noted on routine or video-EEG monitoring. A QOL phone questionnaire, based on the Quality of Life in Childhood Epilepsy tool, was administered to a parent. The authors reviewed each patient's chart for surgical complications, changes in examination, QOL, limited neuropsychological outcomes, and seizure outcomes. They also investigated each chart for MR imaging and EEG findings as well as the patient's epilepsy clinic notes for seizure semiology and frequency.

Results

All patients enjoyed a decrease in seizure frequency and a subjective increase in QOL after PIH. Five patients (71%) achieved Engel Class I or II seizure control. The mean follow-up was 3.64 years (2–5.3 years). One patient is now off all antiseizure medication. No patient had a decrement in Full Scale IQ on postsurgical testing, and 2 (28.5%) of 7 individuals had increased adaptive and social functioning. Postsurgical examination changes included hemiplegia and homonymous hemianopia.

Conclusions

Hemispherotomy in patients with intractable epilepsy is generally reserved for individuals with unilateral epileptiform abnormalities or lesions on MR imaging. Seven patients in this study benefited from surgery despite bilateral seizure onset with improvement in seizure control and overall QOL. Thus, bilateral ictal onset does not necessarily preclude consideration for hemispherotomy in selected patients with severe medically refractory epilepsy.

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Alexander G. Chartrain, Ahmed J. Awad, Justin R. Mascitelli, Hazem Shoirah, Thomas J. Oxley, Rui Feng, Matthew Gallitto, Reade De Leacy, Johanna T. Fifi, and Christopher P. Kellner

Endovascular thrombectomy device improvements in recent years have served a pivotal role in improving the success and safety of the thrombectomy procedure. As the intervention gains widespread use, developers have focused on maximizing the reperfusion rates and reducing procedural complications associated with these devices. This has led to a boom in device development. This review will cover novel and emerging technologies developed for endovascular thrombectomy.

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Ethan Cottrill, Zach Pennington, A. Karim Ahmed, Daniel Lubelski, Matthew L. Goodwin, Alexander Perdomo-Pantoja, Erick M. Westbroek, Nicholas Theodore, Timothy Witham, and Daniel Sciubba

OBJECTIVE

Nonunion is a common complication of spinal fusion surgeries. Electrical stimulation technologies (ESTs)—namely, direct current stimulation (DCS), capacitive coupling stimulation (CCS), and inductive coupling stimulation (ICS)—have been suggested to improve fusion rates. However, the evidence to support their use is based solely on small trials. Here, the authors report the results of meta-analyses of the preclinical and clinical data from the literature to provide estimates of the overall effect of these therapies at large and in subgroups.

METHODS

A systematic review of the English-language literature was performed using PubMed, Embase, and Web of Science databases. The query of these databases was designed to include all preclinical and clinical studies examining ESTs for spinal fusion. The primary endpoint was the fusion rate at the last follow-up. Meta-analyses were performed using a Freeman-Tukey double arcsine transformation followed by random-effects modeling.

RESULTS

A total of 33 articles (17 preclinical, 16 clinical) were identified, of which 11 preclinical studies (257 animals) and 13 clinical studies (2144 patients) were included in the meta-analysis. Among preclinical studies, the mean fusion rates were higher among EST-treated animals (OR 4.79, p < 0.001). Clinical studies similarly showed ESTs to increase fusion rates (OR 2.26, p < 0.001). Of EST modalities, only DCS improved fusion rates in both preclinical (OR 5.64, p < 0.001) and clinical (OR 2.13, p = 0.03) populations; ICS improved fusion in clinical studies only (OR 2.45, p = 0.014). CCS was not effective at increasing fusion, although only one clinical study was identified. A subanalysis of the clinical studies found that ESTs increased fusion rates in the following populations: patients with difficult-to-fuse spines, those who smoke, and those who underwent multilevel fusions.

CONCLUSIONS

The authors found that electrical stimulation devices may produce clinically significant increases in arthrodesis rates among patients undergoing spinal fusion. They also found that the pro-arthrodesis effects seen in preclinical studies are also found in clinical populations, suggesting that findings in animal studies are translatable. Additional research is needed to analyze the cost-effectiveness of these devices.

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Matthew J. McGirt, John C. Mavropoulos, Laura Y. McGirt, Michael J. Alexander, Allan H. Friedman, Daniel T. Laskowitz, and John R. Lynch

Object. The identification of patients at an increased risk for cerebral vasospasm after subarachnoid hemorrhage (SAH) may allow for more aggressive treatment and improved patient outcomes. Note, however, that blood clot size on admission remains the only factor consistently demonstrated to increase the risk of cerebral vasospasm after SAH. The goal of this study was to assess whether clinical, radiographic, or serological variables could be used to identify patients at an increased risk for cerebral vasospasm.

Methods. A retrospective review was conducted in all patients with aneurysmal or spontaneous nonaneurysmal SAH who were admitted to the authors' institution between 1995 and 2001. Underlying vascular diseases (hypertension or chronic diabetes mellitus), Hunt and Hess and Fisher grades, patient age, aneurysm location, craniotomy compared with endovascular aneurysm stabilization, medications on admission, postoperative steroid agent use, and the occurrence of fever, hydrocephalus, or leukocytosis were assessed as predictors of vasospasm.

Two hundred twenty-four patients were treated for SAH during the review period. One hundred one patients (45%) developed symptomatic vasospasm. Peak vasospasm occurred 5.8 ± 3 days after SAH. There were four independent predictors of vasospasm: Fisher Grade 3 SAH (odds ratio [OR] 7.5, 95% confidence interval [CI] 3.5–15.8), peak serum leukocyte count (OR 1.09, 95% CI 1.02–1.16), rupture of a posterior cerebral artery (PCA) aneurysm (OR 0.05, 95% CI 0.01–0.41), and spontaneous nonaneurysmal SAH (OR 0.14, 95% CI 0.04–0.45). A serum leukocyte count greater than 15 × 109/L was independently associated with a 3.3-fold increase in the likelihood of developing vasospasm (OR 3.33, 95% CI 1.74–6.38).

Conclusions. During this 7-year period, spontaneous nonaneurysmal SAH and ruptured PCA aneurysms decreased the odds of developing vasospasm sevenfold and 20-fold, respectively. The presence of Fisher Grade 3 SAH on admission or a peak leukocyte count greater than 15 × 109/L increased the odds of vasospasm sevenfold and threefold, respectively. Monitoring of the serum leukocyte count may allow for early diagnosis and treatment of vasospasm.

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Alexander P. Marston, Jeffrey T. Jacob, Matthew L. Carlson, Bruce E. Pollock, Colin L. W. Driscoll, and Michael J. Link

OBJECTIVE

Over the last 30 years, stereotactic radiosurgery (SRS) has become an established noninvasive treatment alternative for small- to medium-sized vestibular schwannoma (VS). This study aims to further define long-term SRS tumor control in patients with documented pretreatment tumor growth for whom conservative observation failed.

METHODS

A prospective clinical database was queried, and patients with sporadic VS who elected initial observation and subsequently underwent SRS after documented tumor growth between 2004 and 2014 were identified. Posttreatment tumor growth or shrinkage was determined by a ≥ 2-mm increase or decrease in maximum linear dimension, respectively.

RESULTS

Sixty-eight patients met study inclusion criteria. The median pre- and posttreatment observation periods were 16 and 43.5 months, respectively. The median dose to the tumor margin was 13 Gy (range 12–14 Gy), and the median maximum dose was 26 Gy (range 24–28 Gy). At the time of treatment, 59 tumors exhibited extracanalicular (EC) extension, and 9 were intracanalicular (IC). Of the 59 EC VSs, 50 (85%) remained stable or decreased in size following treatment, and 9 (15%) enlarged by > 2 mm. Among EC tumors, the median pretreatment tumor growth rate was 2.08 mm/year for tumors that decreased or were stable, compared with 3.26 mm/year for tumors that grew following SRS (p = 0.009). Patients who demonstrated a pretreatment growth rate of < 2.5 mm/year exhibited a 97% tumor control rate, compared with 69% for those demonstrating ≥ 2.5 mm/year of growth prior to SRS (p = 0.007). No other analyzed variables were found to predict tumor growth following SRS.

CONCLUSIONS

Overall, SRS administered using a marginal dose between 12–14 Gy is highly effective in treating VSs in which initial observation fails. Tumor control is achieved in 97% of VSs that exhibit slow (< 2.5 mm/year) pretreatment growth; however, SRS is less successful in treating tumors exhibiting rapid growth (≥ 2.5 mm/year).