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Anthony C. Wang and Roberto C. Heros

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Ashish H. Shah, Anthony C. Wang and Jacques J. Morcos

Superficial arteriovenous malformations (AVMs) with favorable Spetzler-Martin grading are amenable to primary surgical resection. Careful preoperative workup including preoperative angiograms is essential to identify feeding artery aneurysms and deep venous drainage. The authors present a 37-year-old female who presented with a Spetzler-Martin Grade II right parietal superficial AVM with a 5-mm feeding artery aneurysm from the posterior cerebral artery. Given the risk of hemorrhage, the AVM was resected completely without any complications. On subsequent postoperative angiograms, the feeding artery aneurysm diminished in caliber. Feeding artery aneurysms may regress spontaneously after resection of an AVM due to flow-related changes.

The video can be found here: https://youtu.be/PpwODc9iI3g.

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Simon Buttrick, Jacques J. Morcos, Mohamed S. Elhammady and Anthony C. Wang

Extradural anterior clinoidectomy is a versatile technique to increase exposure of the sellar and parasellar region. It is of particular use in the resection of clinoidal meningiomas, as sphenoidal and clinoidal hyperostosis can cause compression of the optic nerve. Extradural clinoidectomy follows a series of steps, consisting of (1) unroofing of the superior orbital fissure, (2) unroofing of the optic canal, (3) removal of the optic strut, and (4) removal of the anterior clinoid process. The authors show these steps in detail, as well as their application to the resection of a large clinoidal meningioma.

The video can be found here: https://youtu.be/O1Fcef29ETg.

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Huan Wang, Robert J. Spinner and Anthony J. Windebank

Object

Contralateral C-7 nerve transfer has been used clinically for more than 20 years. The increased interest in studies of transfer effectiveness at different target muscles, posttransfer cocontraction, and brain plasticity has prompted the need for an animal model. In addition to the conventional electrophysiological, histomorphometric, and biomechanical evaluation modalities, quantitative functional and behavioral evaluation will be crucial in applying this kind of model. The aim of this study was to establish a C-7 transection animal model and quantify the changes in upper-limb joint movement and muscle power.

Methods

A C-7 nerve transection model was created in Sprague-Dawley rats, the brachial plexus of which resembles the human brachial plexus. The impact of C-7 transection on donor limb function—namely, strength, movement, and coordination—was evaluated in 6 rats. Muscle strength (power reported in g) was measured as a grasping task. The active range of motion (ROM; angle reported in °) of the elbow, wrist, and metacarpophalangeal joints was quantified by computerized video motion analysis. Antiresistance coordinated movement (speed reported in seconds) was assessed by the vertical rope-climbing test. These tests were carried out before surgery and at 2, 4, 6, 8, 10, 14, 21, and 28 days after C-7 transection. Repeated-measures 1-way analysis of variance was applied for statistical analysis. When the overall probability value was < 0.05, the Dunnett multiple-comparison posttest was used to compare postoperative values with preoperative baseline values.

Results

Immediately after C-7 transection, the mean ± SD grip strength declined from 378.50 ± 20.55 g to 297.77 ± 15.04 g. Active elbow extension was impaired, as shown by a significant decrease of the elbow extension angle. The speed of vertical rope climbing was also reduced. Elbow flexion, wrist flexion and extension, and metacarpophalangeal joint flexion and extension were not impaired. Fast recovery of motor function was observed thereafter. Grip strength, range of active elbow extension, and speed of rope climbing returned to baseline values at postoperative Days 4, 8, and 8, respectively.

Conclusions

The ROM and muscle strength of the upper limb in rats can be measured quantitatively in studies that simulate clinical situations. Application of these functional evaluation modalities in a C-7 nerve transection rat model confirmed that transection of C-7 causes only temporary functional dysfunction to the donor limb. The results obtained in this animal model mimic those seen in humans who undergo contralateral C-7 nerve harvesting.

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Robert T. Buckley, Anthony C. Wang, John W. Miller, Edward J. Novotny and Jeffrey G. Ojemann

OBJECTIVE

Laser ablation is a novel, minimally invasive procedure that utilizes MRI-guided thermal energy to treat epileptogenic and other brain lesions. In addition to treatment of mesial temporal lobe epilepsy, laser ablation is increasingly being used to target deep or inoperable lesions, including hypothalamic hamartoma (HH), subependymal giant cell astrocytoma (SEGA), and exophytic intrinsic hypothalamic/third ventricular tumors. The authors reviewed their early institutional experience with these patients to characterize clinical outcomes in patients undergoing this procedure.

METHODS

A retrospective cohort (n = 12) of patients undergoing laser ablation at a single institution was identified, and clinical and radiographic records were reviewed.

RESULTS

Laser ablation was successfully performed in all patients. No permanent neurological or endocrine complications occurred; 2 (17%) patients developed acute obstructive hydrocephalus or shunt malfunction following treatment. Laser ablation of HH resulted in seizure freedom (Engel Class I) in 67%, with the remaining patients having a clinically significant reduction in seizure frequency of greater than 90% compared with preoperative baseline (Engel Class IIB). Treatment of SEGAs resulted in durable clinical and radiographic tumor control in 2 of 3 cases, with one patient receiving adjuvant everolimus and the other receiving no additional therapy. Palliative ablation of hypothalamic/third ventricular tumors resulted in partial tumor control in 1 of 3 patients.

CONCLUSIONS

Early experience suggests that laser ablation is a generally safe, durable, and effective treatment for patients harboring HHs. It also appears effective for local control of SEGAs, especially in combination therapy with everolimus. Its use as a palliative treatment for intrinsic hypothalamic/deep intraventricular tumors was less successful and associated with a higher risk of serious complications. Additional experience and long-term follow-up will be beneficial in further characterizing the effectiveness and risk profile of laser ablation in treating these lesions in comparison with conventional resective surgery or stereotactic radiosurgery.

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Anthony C. Wang, Khoi D. Than, Arnold B. Etame, Frank La Marca and Paul Park

Object

Transcranial motor evoked potential (TcMEP) monitoring is frequently used in complex spinal surgeries to prevent neurological injury. Anesthesia, however, can significantly affect the reliability of TcMEP monitoring. Understanding the impact of various anesthetic agents on neurophysiological monitoring is therefore essential.

Methods

A literature search of the National Library of Medicine database was conducted to identify articles pertaining to anesthesia and TcMEP monitoring during spine surgery. Twenty studies were selected and reviewed.

Results

Inhalational anesthetics and neuromuscular blockade have been shown to limit the ability of TcMEP monitoring to detect significant changes. Hypothermia can also negatively affect monitoring. Opioids, however, have little influence on TcMEPs. Total intravenous anesthesia regimens can minimize the need for inhalational anesthetics.

Conclusions

In general, selecting the appropriate anesthetic regimen with maintenance of a stable concentration of inhalational or intravenous anesthetics optimizes TcMEP monitoring.

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Arnold B. Etame, Anthony C. Wang, Khoi D. Than, Frank La Marca and Paul Park

Object

Symptomatic cervical kyphosis can result from a variety of causes. Symptoms can include pain, neurological deficits, and functional limitation due to loss of horizontal gaze.

Methods

The authors review the long-term functional and radiographic outcomes following surgery for symptomatic cervical kyphosis by performing a PubMed database literature search.

Results

Fourteen retrospective studies involving a total of 399 patients were identified. Surgical intervention included ventral, dorsal, or circumferential approaches. Analysis of the degree of deformity correction and functional parameters demonstrated significant postsurgical improvement. Overall, patient satisfaction appeared high. Five studies reported mortality with rates ranging from 3.1 to 6.7%. Major medical complications after surgery were reported in 5 studies with rates ranging from 3.1 to 44.4%. The overall neurological complication rate was 13.5%.

Conclusions

Although complications are not insignificant, surgery appears to be an effective option when conservative measures fail to provide relief.

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K. Anthony Kim, Michael Y. Wang, Pamela M. Griffith, Susan Summers and Michael L. Levy

The authors conducted a study to describe the incidence and types of fall-related head injury observed at a pediatric trauma center.

We performed a retrospective analysis of all patients under 15 years of age treated for fall-related trauma between 1992 and 1998. Falls were classified as low (< 15 feet) and high level (≥ 15 feet).

Seven hundred twenty-nine cases were identified with a mortality rate of 1.7%. A fall of greater than 15 feet (high-level fall) was associated with a higher mortality rate than low-level falls (2.4% compared with 1.0%, respectively). Ninety-eight patients had sustained a calvarial fracture and 93 experienced a basal skull fracture. Twenty-six patients had suffered a cerebral contusion, 25 a sub-arachnoid hemorrhage, 22 a subdural hematoma, and 12 had an epidural hematoma. Forty-nine patients required surgery for traumatic injuries; of these, 10 underwent craniotomy for evacuation of a blood clot. Height was not predictive of the Glasgow Coma Scale (GCS) score. In all four deaths resulting from a low-level fall there was an admission GCS score of 3, and abnormal findings were demonstrated on computerized tomography scanning. Death from high-level falls was attributable to either intracranial injuries (50%) or severe extracranial injuries (50%).

Intracranial injury is the major source of fall-related death in children and, unlike extracranial insults, brain injuries are sustained with equal frequency from low- and high-level falls in this population. The only cause of mortality from low-level falls was intracranial injury. Trauma triage criteria must account for these differences in the pediatric population.

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Paul Khoueir, K. Anthony Kim and Michael Y. Wang

✓Numerous new posterior dynamic stabilization (PDS) devices have been developed for the treatment of disorders of the lumbar spine. In this report the authors provide a classification scheme for these devices and describe several clinical situations in which the instrumentation may be expected to play a role. By using this classification, the PDSs that are now available and those developed in the future can be uniformly categorized.

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Namath S. Hussain, Paul P. Wang, Carol James, Benjamin S. Carson and Anthony M. Avellino

✓ The placement of a ventriculoperitoneal (VP) shunt is the most common form of treatment for hydrocephalus. Although allergic reactions to the silicone in shunt hardware are very rare, the authors describe a case of silicone allergy causing multiple ventricular shunt revisions. A 24-year-old man, who had undergone multiple VP shunt revisions, presented with shunt malfunction caused by allergic reaction of the tissues surrounding the shunt tubing. The patient's existing silicone-based shunt was replaced with a new polyurethane system, including the proximal and distal catheters as well as the valve mechanism. Contrary to recommendations in previous studies of silicone shunt allergies, long-term immunosuppression was not initiated. The patient was followed up for more than 8 years without recurrence of an allergic reaction to the shunt. This outcome indicates that replacing the original silicone-based shunt system with a polyurethane-based system alone is sufficient in the treatment of a silicone shunt allergy.