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  • Author or Editor: Steven W. Hwang x
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Ron I. Riesenburger, Steven W. Hwang, Clemens M. Schirmer, Vasilios Zerris, Julian K. Wu, Kerry Mahn, Paul Klimo Jr., John Mignano, Clinton J. Thompson and Kevin C. Yao


Gamma Knife surgery (GKS) has been shown to be effective in treating trigeminal neuralgia (TN). Existing studies have demonstrated success rates of 69.1–85% with median follow-up intervals of 19–60 months. However, series with uniform long-term follow-up data for all patients have been lacking. In the present study the authors examined outcomes in a series of patients with TN who underwent a single GKS treatment followed by a minimum follow-up of 36 months. They used a clinical scale that simplifies the reporting of outcome data for patients with TN.


Fifty-three consecutive patients with typical, intractable TN received a median maximum radiation dose of 80 Gy applied with a single 4-mm isocenter to the affected trigeminal nerve. Follow-up data were obtained by clinical examination and questionnaire. Outcome results were categorized into the following classes (in order of decreasing success): Class 1A, complete pain relief without medications; 1B, complete pain relief with either a decrease or no change in medications; 1C, ≥ 50% pain relief without medications; 1D, ≥ 50% pain relief with either a decrease or no change in medications; and Class 2, < 50% pain relief and/or increase in medications. Patients with Class 1A–1D outcome (equivalent to Barrow Neurological Institute Grades I–IIIb) were considered to have a good treatment outcome, whereas in patients with Class 2 outcome (equivalent to Barrow Neurological Institute Grades IV and V) treatment was considered to have failed.


A good treatment outcome from initial GKS was achieved in 31 (58.5%) patients for whom the mean follow-up period was 48 months (range 36–66 months). Outcomes at last follow-up were reflected by class status: Class 1A, 32.1% of patients; 1B, 1.9%; 1C, 3.8%; 1D, 20.8%; and Class 2, 41.5%. Statistical analysis showed no difference in outcomes between patients previously treated with microvascular decompression or rhizotomy compared with patients with no previous surgical treatments. Thirty-six percent of patients reported some degree of posttreatment facial numbness. Anesthesia dolorosa did not develop in any patient.


Despite a time-dependent deterioration in the success rate of GKS for medically intractable TN, the authors' study showed that > 50% of patients can be expected to have a good outcome based on their scoring system, with ~ 33% having an ideal outcome (pain free with no need for medications). Long-term data, as those presented here, are important when counseling patients on their treatment options.

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Clemens M. Schirmer, Steven W. Hwang, Ron I. Riesenburger, In Sup Choi and Carlos A. David

Cobb syndrome represents the concurrent findings of a metameric spinal vascular malformation and a cutaneous vascular malformation within several dermatomes of each other. This rare entity engenders many difficult decisions with respect to appropriate therapeutic management. Historically, surgical excision carried a high morbidity, and conservative management without intervention was preferred. More recently, several cases of endovascular embolization have been reported with good success.

The authors describe the case of a 17-year-old boy who presented with a right gluteal angioma and was found to have a spinal arteriovenous malformation. Multiple embolizations failed to prevent neurological deterioration, and the patient eventually became wheelchair dependent. Surgical excision of the malformation led to partial recovery of neurological function, and at the latest follow-up, 52 months postoperatively, the patient was able to ambulate independently. This case demonstrates the successful treatment of a patient with Cobb syndrome with surgical excision after multiple refractory embolizations. A multidisciplinary approach, which balances the patient's current neurological function against the risks and potential gains from any interventional and surgical procedure, is recommended.

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Mark Henry, Katherine Scarlata, Ron I. Riesenburger, James Kryzanski, Leslie Rideout, Amer Samdani, Andrew Jea and Steven W. Hwang


Although MRI with short-term T1 inversion recovery (STIR) sequencing has been widely adopted in the clearance of cervical spine in adults who have sustained trauma, its applicability for cervical spine clearance in pediatric trauma patients remains unclear. The authors sought to review a Level 1 trauma center's experience using MRI for posttraumatic evaluation of the cervical spine in pediatric patients.


A pediatric trauma database was retrospectively queried for patients who received an injury warranting radiographic imaging of the cervical spine and had a STIR-MRI sequence of the cervical spine performed within 48 hours of injury between 2002 and 2011. Demographic, radiographic, and outcome data were retrospectively collected through medical records.


Seventy-three cases were included in the analysis. The mean duration of follow-up was 10 months (range 4 days–7 years). The mean age of the patients at the time of trauma evaluation was 8.3 ± 5.8 years, and 65% were male. The majority of patients were involved in a motor vehicle accident. In 70 cases, the results of MRI studies were negative, and the patients were cleared prior to discharge with no clinical suggestion of instability on follow-up. In 3 cases, the MRI studies had abnormal findings; 2 of these 3 patients were cleared with dynamic radiographs during the same admission. Only 1 patient had an unstable injury and required surgical stabilization. The sensitivity of STIR MRI to detect cervical instability was 100% with a specificity of 97%. The positive predictive value was 33% and the negative predictive value was 100%.


Although interpretation of our results are diminished by limitations of the study, in our series, STIR MRI in routine screening for pediatric cervical trauma had a high sensitivity and slightly lower specificity, but may have utility in future practices and should be considered for implementation into protocols.

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Mina G. Safain, Shane M. Burke, Ron I. Riesenburger, Vasilios Zerris and Steven W. Hwang


The standard surgical release of a tethered cord may result in recurrent scar formation and occasionally be associated with retethering. The application of spinal shortening procedures to this challenging problem potentially can reduce tension on the retethered spinal cord while minimizing the difficulties inherent in traditional lumbosacral detethering revision. Although spinal shortening procedures have proven clinical benefit in patients with a recurrent tethered cord, it is unclear how much shortening is required to achieve adequate reduction in spinal cord tension or what impact these osteotomies have on dural buckling.


The authors calculated mean values from 4 human cadavers to evaluate the effect of 3 different spinal shortening procedures—Smith-Petersen osteotomy (SPO), pedicle subtraction osteotomy (PSO), and vertebral column resection (VCR)—on spinal cord tension and dural buckling. Three cadavers were dedicated to the measurement of spinal cord tension, and 3 other cadavers were devoted to myelography to measure dural buckling parameters.


The SPO was associated with a maximal decrease in spinal cord tension of 16.1% from baseline and no dural buckling with any degree of closure. The PSO led to a mean maximal decrease in spinal cord tension of 63.1% from baseline at 12 mm of closure and demonstrated a direct linear relationship between dural buckling and increasing osteotomy closure. Finally, VCR closure correlated with a mean maximal decrease in spinal cord tension of 87.2% from baseline at 10 mm of closure and also showed a direct linear relationship between dural buckling and increases in osteotomy closure.


In this cadaveric experiment, the SPO did not lead to appreciable tension reduction, while a substantial response was seen with both the PSO and VCR. The rate of tension reduction may be steeper for the VCR than the PSO. Adequate tension relief while minimizing dural buckling may be optimal with 12–16 mm of posterior osteotomy closure based on this cadaveric experiment.

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Charles E. Mackel, Brent C. Morel, Jesse L. Winer, Hannah G. Park, Megan Sweeney, Robert S. Heller, Leslie Rideout, Ron I. Riesenburger and Steven W. Hwang

The authors looked at all of the pediatric patients with a head injury who were transferred from other hospitals to their own over 12 years and tried to identify factors that would allow patients to stay closer to home at their local hospitals and not be transferred. Many patients with isolated, nondisplaced skull fractures or negative CT imaging likely could have avoided transfer. While hospitals should be cautious, this may help families stay closer to home.