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Matthew R. MacEwan, Paul Gamble, Manu Stephen and Wilson Z. Ray

OBJECTIVE

Electrical stimulation of peripheral nerve tissue has been shown to accelerate axonal regeneration. Yet existing methods of applying electrical stimulation to injured peripheral nerves have presented significant barriers to clinical translation. In this study, the authors examined the use of a novel implantable wireless nerve stimulator capable of simultaneously delivering therapeutic electrical stimulation of injured peripheral nerve tissue and providing postoperative serial assessment of functional recovery.

METHODS

Flexible wireless stimulators were fabricated and implanted into Lewis rats. Thin-film implants were used to deliver brief electrical stimulation (1 hour, 20 Hz) to sciatic nerves after nerve crush or nerve transection-and-repair injuries.

RESULTS

Electrical stimulation of injured nerves via implanted wireless stimulators significantly improved functional recovery. Brief electrical stimulation was observed to increase the rate of functional recovery after both nerve crush and nerve transection-and-repair injuries. Wireless stimulators successfully facilitated therapeutic stimulation of peripheral nerve tissue and serial assessment of nerve recovery.

CONCLUSIONS

Implantable wireless stimulators can deliver therapeutic electrical stimulation to injured peripheral nerve tissue. Implantable wireless nerve stimulators might represent a novel means of facilitating therapeutic electrical stimulation in both intraoperative and postoperative settings.

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Thomas J. Wilson, B. Matthew Howe, Shelby A. Stewart, Robert J. Spinner and Kimberly K. Amrami

OBJECTIVE

This study aimed to define a set of clinicoradiological parameters with a high specificity for the diagnosis of intraneural perineurioma, obviating the need for operative tissue diagnosis.

METHODS

The authors retrospectively reviewed MR images obtained in a large cohort of patients who underwent targeted fascicular biopsy and included only those patients for whom the biopsy yielded a diagnosis. Clinical and radiological findings were then tested for their ability to predict a tissue diagnosis of intraneural perineurioma. The authors propose a new set of diagnostic criteria, referred to as the Perineurioma Diagnostic Criteria. The sensitivity, specificity, positive predictive value, and negative predictive value of several clinicoradiological methods of diagnosis were compared.

RESULTS

A total of 195 patients who underwent targeted fascicular biopsy were included in the cohort, of whom 51 had a tissue diagnosis of intraneural perineurioma. When the clinicoradiological methods used in this study were compared, the highest sensitivity (0.86), negative predictive value (0.95), and F1 score (0.88) were observed for the decision trees generated in C5.0 and rPart, whereas the highest specificity (1.0) and positive predictive value (1.0) were observed for the Perineurioma Diagnostic Criteria.

CONCLUSIONS

This study identified clinical and radiological features that are associated with a diagnosis of perineurioma. The Perineurioma Diagnostic Criteria were determined to be the following: 1) no cancer history, 2) unifocal disease, 3) moderate to severe hyperintensity on T2-weighted MR images, 4) moderate to severe contrast enhancement, 5) homogeneous contrast enhancement, 6) fusiform shape, 7) enlargement of the involved nerves, and 8) age ≤ 40 years. Use of the Perineurioma Diagnostic Criteria obviates the need for tissue diagnosis when all of the criteria are satisfied.

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Thomas J. Wilson, Kathleen E. McCoy, Wajd N. Al-Holou, Sergio L. Molina, Matthew D. Smyth and Stephen E. Sullivan

OBJECTIVE

The aim of this paper is to compare the accuracy of the freehand technique versus the use of intraoperative guidance (either ultrasound guidance or frameless stereotaxy) for placement of parietooccipital ventricular catheters and to determine factors associated with reduced proximal shunt failure.

METHODS

This retrospective cohort study included all patients from 2 institutions who underwent a ventricular cerebrospinal fluid (CSF) shunting procedure in which a new parietooccipital ventricular catheter was placed between January 2005 and December 2013. Data abstracted for each patient included age, sex, method of ventricular catheter placement, side of ventricular catheter placement, Evans ratio, and bifrontal ventricular span. Postoperative radiographic studies were reviewed for accuracy of ventricular catheter placement. Medical records were also reviewed for evidence of shunt failure requiring revision. Standard statistical methods were used for analysis.

RESULTS

A total of 257 patients were included in the study: 134 from the University of Michigan and 123 from Washington University in St. Louis. Accurate ventricular catheter placement was achieved in 81.2% of cases in which intraoperative guidance was used versus 67.3% when the freehand technique was used. Increasing age reduced the likelihood of accurate catheter placement (OR 0.983, 95% CI 0.971–0.995; p = 0.005), while the use of intraoperative guidance significantly increased the likelihood (OR 2.809, 95% CI 1.406–5.618; p = 0.016). During the study period, 108 patients (42.0%) experienced shunt failure, 79 patients (30.7%) had failure involving the proximal catheter, and 53 patients (20.6%) had distal failure (valve or distal catheter). Increasing age reduced the likelihood of being free from proximal shunt failure (OR 0.983, 95% CI 0.970–0.995; p = 0.008), while both the use of intraoperative guidance (OR 2.385, 95% CI 1.227–5.032; p = 0.011), and accurate ventricular catheter placement (OR 3.424, 95% CI 1.796–6.524; p = 0.009) increased the likelihood.

CONCLUSIONS

The use of intraoperative guidance during parietooccipital ventricular catheter placement as part of a CSF shunt system significantly increases the likelihood of accurate catheter placement and subsequently reduces the rate of proximal shunt failure.

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P. Troy Henning, Thomas J. Wilson, Matthew Willsey, Jessin K. John, Miriana Popadich and Lynda J. S. Yang

Surgical transection of sensory nerves in the treatment of intractable neuropathic pain is a commonly performed procedure. At times these cases can be particularly challenging when encountering obese patients, when targeting deeper nerves or those with a variable branching pattern, or in the case of repeat operations. In this case series, the authors describe their experience with ultrasound-guided surgical instrument placement during transection of a saphenous nerve in the region of prior vascular surgery in 1 patient and in the lateral femoral cutaneous nerve in 2 obese patients. The authors also describe this novel technique and provide pilot data that suggests ultrasound-assisted surgery may allow for complex cases to be completed in an expedited fashion through smaller incisions.

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Alexander K. Powers, Matthew T. Neal, Louis C. Argenta, John A. Wilson, Anthony J. DeFranzo and Stephen B. Tatter

The aim in this study was to describe the safety and efficacy of vacuum-assisted closure (VAC) in patients with complex cranial wounds with extensive scalp, bone, and dural defects who were not candidates for immediate free tissue transfer. Five patients (4 men and 1 woman) ages 24–73 years with complex cranial wounds were treated with VAC at Wake Forest Baptist Medical Center. Etiologies included trauma, squamous cell carcinoma, and malignant meningioma. Cutaneous wound defects measured as large as 15 cm in diameter. Four of the 5 patients had open skull defects with concomitant dural defects, and 1 patient had dural dehiscence. After surgical debridement, all 5 patients were treated with the direct application of a VAC device to a reapproximated dura mater (1 patient), to a pericranial flap (1 patient), or to a regenerative tissue matrix overlying CNS tissue (3 patients). In all cases involving open cranial wounds, the VAC device promoted granulation tissue formation over the dural substitute, prevented CSF leakage, and kept the wounds free from local infection. The duration of VAC therapy ranged from 16 to 91 days. Although VAC therapy was intended as a temporary measure until these patients could be stabilized for larger tissue transfer procedures or they succumbed to their primary pathology, 1 patient had a successful skin graft following VAC therapy. Hydrocephalus requiring shunt placement developed in 2 patients during VAC therapy. The VAC dressings applied to a tissue matrix or other barrier over brain tissue in extensive cranial wounds are safe and well tolerated, providing a functional barrier and preventing infection.

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Scott Campbell, Richard Theile, Gordon Stuart, Matthew McDonald, Stephen Sinnott, Kieran Frawley, John Wilson and Alan Isles

✓ Craniopagus is a rare and intriguing condition with an incidence of one in 2.5 million births. The chance of a neurosurgeon seeing a case in a working lifetime is unlikely. The chances of two cases from the same community within 12 months are remote in the extreme. The authors present a second case of craniopagus born and separated in Brisbane, Australia, in 2001 and discuss the intricacies of surgical separation and the lessons learned.

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Matthew A. Kirkman, Maria Ahmed, Angelique F. Albert, Mark H. Wilson, Dipankar Nandi and Nick Sevdalis

Object

There is increasing evidence that simulation provides high-quality, time-effective training in an era of resident duty-hour restrictions. Simulation may also permit trainees to acquire key skills in a safe environment, important in a specialty such as neurosurgery, where technical error can result in devastating consequences. The authors systematically reviewed the application of simulation within neurosurgical training and explored the state of the art in simulation within this specialty. To their knowledge this is the first systematic review published on this topic to date.

Methods

The authors searched the Ovid MEDLINE, Embase, and PsycINFO databases and identified 4101 articles; 195 abstracts were screened by 2 authors for inclusion. The authors reviewed data on study population, study design and setting, outcome measures, key findings, and limitations.

Results

Twenty-eight articles formed the basis of this systematic review. Several different simulators are at the neurosurgeon's disposal, including those for ventriculostomy, neuroendoscopic procedures, and spinal surgery, with evidence for improved performance in a range of procedures. Feedback from participants has generally been favorable. However, study quality was found to be poor overall, with many studies hampered by nonrandomized design, presenting normal rather than abnormal anatomy, lack of control groups and long-term follow-up, poor study reporting, lack of evidence of improved simulator performance translating into clinical benefit, and poor reliability and validity evidence. The mean Medical Education Research Study Quality Instrument score of included studies was 9.21 ± 1.95 (± SD) out of a possible score of 18.

Conclusions

The authors demonstrate qualitative and quantitative benefits of a range of neurosurgical simulators but find significant shortfalls in methodology and design. Future studies should seek to improve study design and reporting, and provide long-term follow-up data on simulated and ideally patient outcomes.

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Matthew C. Davis, Betsy D. Hopson, Jeffrey P. Blount, Rachel Carroll, Tracey S. Wilson, Danielle K. Powell, Amie B. Jackson McLain and Brandon G. Rocque

OBJECTIVE

Predictors of permanent disability among individuals with spinal dysraphism are not well established. In this study, the authors examined potential risk factors for self-reported permanent disability among adults with spinal dysraphism.

METHODS

A total of 188 consecutive individuals undergoing follow-up in an adult spinal dysraphism clinic completed a standardized National Spina Bifida Patient Registry survey. Chi-square tests and logistic regression were used to assess bivariate relationships, while multivariate logistic regression was used to identify factors independently associated with self-identification as “permanently disabled.”

RESULTS

A total of 106 (56.4%) adults with spina bifida identified themselves as permanently disabled. On multivariate analysis, relative to completion of primary and/or secondary school, completion of technical school (OR 0.01, 95% CI 0–0.40; p = 0.021), some college (OR 0.22, 95% CI 0.08–0.53; p < 0.001), college degree (OR 0.06, 95% CI 0.003–0.66; p = 0.019), and holding an advanced degree (OR 0.12, 95% CI 0.03–0.45; p = 0.002) were negatively associated with permanent disability. Relative to open myelomeningocele, diagnosis of closed spinal dysraphism was also negatively associated with permanent disability (OR 0.20, 95% CI 0.04–0.90; p = 0.036). Additionally, relative to no stool incontinence, stool incontinence occurring at least daily (OR 6.41, 95% CI 1.56–32.90; p = 0.009) or more than weekly (OR 3.43, 95% CI 1.10–11.89; p = 0.033) were both positively associated with permanent disability. There was a suggestion of a dose-response relationship with respect to the influence of educational achievement and frequency of stool incontinence on the likelihood of permanent disability.

CONCLUSIONS

The authors’ findings suggest that level of education and degree of stool incontinence are the strongest predictors of permanent disability among adults with spinal dysraphism. These findings will be the basis of efforts to improve community engagement and to improve readiness for transition to adult care in a multidisciplinary pediatric spina bifida clinic.

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David Y. C. Chan, Anderson C. O. Tsang, Wilson W. S. Ho, Kevin K. F. Cheng, Lai F. Li, Frederick C. P. Tsang, Benedict B. T. Taw, Jenny K. S. Pu, Gilberto K. K. Leung and Matthew W. M. Lui

OBJECTIVE

Hydrocephalus with a blocked ventriculoperitoneal (VP) shunt is a life-threatening condition. Emergency endoscopic third ventriculostomy (ETV) is a potential treatment option. The aim of the study was to identify independent risk factors associated with failure of ETV in treating patients with blocked shunts.

METHODS

The authors retrospectively reviewed data from consecutive patients admitted for blocked shunt treated by ETV during the study period from 2000 to 2016. Univariate and multivariate analyses were performed to identify independent factors associated with failed ETV for blocked shunts, such as age, sex, history of CNS infection, number of previous shunt revisions, operations performed as an emergency or elective, number of specialists, and other factors.

RESULTS

In total, 121 patients underwent ETV during the study period. Of these, 31 patients (25.6%) had ETV for treatment of a blocked shunt. In 25 (80.6%) of 31 ETV was performed as an emergency procedure. There was no significant difference in the success rate of ETV depending on whether it was performed as an emergency procedure (64% [16/25]) or an elective procedure (66.7% [4/6]; OR 0.062, 95% CI 0.001–2.708; p = 0.149). Univariate and multivariate analyses identified that history of a CNS infection was an independent risk factor for failure of ETV in treating patients with a blocked shunt (OR 0.030, 95% CI 0.001–0.888; p = 0.043).

CONCLUSIONS

Emergency ETV had a comparable success rate as elective ETV. A history of CNS infection is an independent predictor of ETV failure in treating patients with blocked shunts.

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Christina K. Magill, Amy M. Moore, Ying Yan, Alice Y. Tong, Matthew R. MacEwan, Andrew Yee, Ayato Hayashi, Daniel A. Hunter, Wilson Z. Ray, Philip J. Johnson, Alexander Parsadanian, Terence M. Myckatyn and Susan E. Mackinnon

Object

Glial cell line–derived neurotrophic factor (GDNF) has potent survival effects on central and peripheral nerve populations. The authors examined the differential effects of GDNF following either a sciatic nerve crush injury in mice that overexpressed GDNF in the central or peripheral nervous systems (glial fibrillary acidic protein [GFAP]–GDNF) or in the muscle target (Myo-GDNF).

Methods

Adult mice (GFAP-GDNF, Myo-GDNF, or wild-type [WT] animals) underwent sciatic nerve crush and were evaluated using histomorphometry and muscle force and power testing. Uninjured WT animals served as controls.

Results

In the sciatic nerve crush, the Myo-GDNF mice demonstrated a higher number of nerve fibers, fiber density, and nerve percentage (p < 0.05) at 2 weeks. The early regenerative response did not result in superlative functional recovery. At 3 weeks, GFAP-GDNF animals exhibit fewer nerve fibers, decreased fiber width, and decreased nerve percentage compared with WT and Myo-GDNF mice (p < 0.05). By 6 weeks, there were no significant differences between groups.

Conclusions

Peripheral delivery of GDNF resulted in earlier regeneration following sciatic nerve crush injuries than that with central GDNF delivery. Treatment with neurotrophic factors such as GDNF may offer new possibilities for the treatment of peripheral nerve injury.