✓The authors present a unique case of hyperhidrosis as a side effect of a misplaced deep brain stimulation (DBS) electrode near the ventrointermedius (Vim) nucleus in a patient with essential tremor. Magnetic resonance imaging of the brain showed electrode placement in the left anterior thalamus traversing the hypothalamus. High-frequency electrical stimulation possibly resulted in unilateral activation of the efferent sympathetic pathways in the zona incerta. Although a rare complication, hypothalamic dysfunction may occur as a stimulation-related side effect of Vim-DBS.
Alan Diamond, Christopher Kenney, Michael Almaguer and Joseph Jankovic
Michael P. Steinmetz, Christopher D. Kager and Edward C. Benzel
Object. Cervical kyphotic deformation may develop after surgery involving either the ventral or dorsal approach. Regardless of the cause, the development of a cervical kyphotic deformity should be avoided, if possible, and corrected if present, when appropriate. The authors describe their experience with a technique for the ventral correction of iatrogenic (postoperative) cervical kyphosis.
Methods. A retrospective review of cases involving correction of postoperative iatrogenic cervical kyphosis via an ventral approach was performed. The authors conducted an ventral approach to kyphosis correction. The procedure required specific head positioning (in extension), convergent distraction pins, and an ventrally placed implant (axially dynamic when appropriate) with multiple points of fixation including at least one point of intermediate fixation. The pre- and postoperative sagittal angle and clinical status were evaluated.
During a nearly 14-month period, 12 patients met the inclusion criteria. Ten patients underwent a minimum of 6 months of follow up. They comprised the study population. Most patients presented with mechanical neck pain as part of their symptom profile. The mean magnitude of deformity correction (pre- to postoperative) was 20° of lordosis. The mean postoperative sagittal angle was 6° of lordosis. The mean change in the sagittal angle during the follow-up period was 2.2° of lordosis.
Conclusions. The ventral approach to correction of cervical deformity led to the achievement of lordosis in all but one patient. This posture was effectively maintained during the follow-up period. All patients exhibited improvement postoperatively; three experienced complete resolution of their preoperative symptoms. When symptoms are related to postsurgical kyphosis, deformity correction should be considered. Such a procedure may be performed effectively via an ventral approach in most circumstances.
Nishit Mummareddy, Michael C. Dewan, Michael R. Mercier, Robert P. Naftel, John C. Wellons III and Christopher M. Bonfield
The authors aimed to provide an updated and consolidated report on the epidemiology, management, and functional outcome of cases of myelomeningocele (MMC) in patients with scoliosis.
A comprehensive literature search was performed using MEDLINE, Embase, Google Scholar, and the Cochrane Database of Systematic Reviews on cases of MMC in patients with scoliosis between 1980 and 2016. The initial search yielded 670 reports. After removing duplicates and applying inclusion criteria, we included 32 full-text original articles in this study.
Pooled statistical analysis of the included articles revealed the prevalence of scoliosis in MMC patients to be 53% (95% CI 0.42–0.64). Slightly more females (56%) are affected with both MMC and scoliosis than males. Motor level appears to be a significant predictor of prevalence, but not severity, of scoliosis in MMC patients. Treatment options for these patients include tethered cord release (TCR) and fusion surgeries. Curvature improvement and stabilization after TCR may be limited to patients with milder (< 50°) curves. Meanwhile, more aggressive fusion procedures such as a combined anterior-posterior approach may result in more favorable long-term scoliosis correction, albeit with greater complication rates. Quality of life metrics including ambulatory status and sitting stability are influenced by motor level of the lesion as well as the degree of the scoliosis curvature.
Scoliosis is among the most common and challenging comorbidities from which patients with MMC suffer. Although important epidemiological and management trends are evident, larger, prospective studies are needed to discover ways to more accurately counsel and more optimally treat these patients.
Arjun S. Chandran, Michael Bynevelt and Christopher R. P. Lind
The subthalamic nucleus (STN) is one of the most important stereotactic targets in neurosurgery, and its accurate imaging is crucial. With improving MRI sequences there is impetus for direct targeting of the STN. High-quality, distortion-free images are paramount. Image reconstruction techniques appear to show the greatest promise in balancing the issue of geometrical distortion and STN edge detection. Existing spin echo- and susceptibility-based MRI sequences are compared with new image reconstruction methods. Quantitative susceptibility mapping is the most promising technique for stereotactic imaging of the STN.
Christopher E. Mandigo, Prakash Sampath and Michael G. Kaiser
✓Posterior dynamic stabilization in the lumbar spine is performed in an attempt to reduce loading across the intervertebral disc for the purpose of relieving pain and limiting degeneration while preserving motion. The AccuFlex rod system (Globus Medical, Inc.), a first-generation device, achieves this by changing the properties of the rod within the Protex pedicle screw–based rigid rod system. Helical cuts that have been created in the standard 6.5-mm rod allow for a limited range of motion while providing a posterior tension band that relieves a significant amount of disc loading. The AccuFlex rod system has been approved by the Food and Drug Administration for single-level fusion when used in conjunction with an interbody graft. In a study involving 170 patients who underwent fusion surgery for back pain, the 54 who received the AccuFlex construct had statistically similar fusion rates and outcomes (as assessed by visual analog scale and Short Form-16 scores) when compared with 116 patients treated with rigid rod fixation after 1 year of follow up. Future clinical studies will examine and provide information regarding the impact of AccuFlex on the incidence of adjacent-level disease. Information gained through the clinical experience with AccuFlex will serve as a foundation for the development of a stand-alone dynamic construct.
Michael Garcia, Christopher Daugherty, Bertha Ben Khallouq and Todd Maugans
The Internet is used frequently by patients and family members to acquire information about pediatric neurosurgical conditions. The sources, nature, accuracy, and usefulness of this information have not been examined recently. The authors analyzed the results from searches of 10 common pediatric neurosurgical terms using a novel scoring test to assess the value of the educational information obtained.
Google and Bing searches were performed for 10 common pediatric neurosurgical topics (concussion, craniosynostosis, hydrocephalus, pediatric brain tumor, pediatric Chiari malformation, pediatric epilepsy surgery, pediatric neurosurgery, plagiocephaly, spina bifida, and tethered spinal cord). The first 10 “hits” obtained with each search engine were analyzed using the Currency, Relevance, Authority, Accuracy, and Purpose (CRAAP) test, which assigns a numerical score in each of 5 domains. Agreement between results was assessed for 1) concurrent searches with Google and Bing; 2) Google searches over time (6 months apart); 3) Google searches using mobile and PC platforms concurrently; and 4) searches using privacy settings. Readability was assessed with an online analytical tool.
Google and Bing searches yielded information with similar CRAAP scores (mean 72% and 75%, respectively), but with frequently differing results (58% concordance/matching results). There was a high level of agreement (72% concordance) over time for Google searches and also between searches using general and privacy settings (92% concordance). Government sources scored the best in both CRAAP score and readability. Hospitals and universities were the most prevalent sources, but these sources had the lowest CRAAP scores, due in part to an abundance of self-marketing. The CRAAP scores for mobile and desktop platforms did not differ significantly (p = 0.49).
Google and Bing searches yielded useful educational information, using either mobile or PC platforms. Most information was relevant and accurate; however, the depth and breadth of information was variable. Search results over a 6-month period were moderately stable. Pediatric neurosurgery practices and neurosurgical professional organization websites were inferior (less current, less accurate, less authoritative, and less purposeful) to governmental and encyclopedia-type resources such as Wikipedia. This presents an opportunity for pediatric neurosurgeons to participate in the creation of better online patient/parent educational material.
Michael G. Muhonen, Scott C. Robertson, Jeffrey S. Gerdes and Christopher M. Loftus
✓ Serotonin (5-HT) produces constriction of peripheral collateral blood vessels. Using an animal model, the authors tested the hypothesis that 5-HT constricts collateral vessels in the cerebrum. A branch of the middle cerebral artery (MCA) was occluded proximally and cannulated distally in anesthetized dogs. Blood flow to the area at risk for infarction was detected by perfusing the cannulated MCA branch with microsphere-free blood during systemic injection of radioactive microspheres (shadow flow technique). Blood flow to collateral-dependent and normal cerebrum was measured during intravenous infusion of 5-HT (10 and 40 mg/kg/minute). Serotonin produced a dose-related reduction of blood flow to collateral-dependent cerebrum, increased collateral vessel resistance in large cerebral arteries and collateral vessels, and decreased cerebral artery perfusion pressure. In contrast, blood flow to normal cerebrum was not altered because a decrease in small vessel resistance effectively compensated for a decrease in MCA perfusion pressure. These findings indicate that 5-HT produces constriction of collateral vessels in the cerebrum. This response is clearly different from normal small cerebral vessels, which dilate during 5-HT infusion.
Rudolf Fahlbusch, Oliver Ganslandt, Michael Buchfelder, Werner Schott and Christopher Nimsky
Object. The aim of this study was to evaluate whether intraoperative magnetic resonance (MR) imaging can increase the efficacy of transsphenoidal microsurgery, primarily in non—hormone-secreting intra- and suprasellar pituitary macroadenomas.
Methods. Intraoperative imaging was performed using a 0.2-tesla MR imager, which was located in a specially designed operating room. The patient was placed supine on the sliding table of the MR imager, with the head placed near the 5-gauss line. A standard flexible coil was placed around the patient's forehead. Microsurgery was performed using MR-compatible instruments. Image acquisition was started after the sliding table had been moved into the center of the magnet. Coronal and sagittal T1-weighted images each required over 8 minutes to acquire, and T2-weighted images were obtained optionally. To assess the reliability of intraoperative evaluation of tumor resection, the intraoperative findings were compared with those on conventional postoperative 1.5-tesla MR images, which were obtained 2 to 3 months after surgery.
Among 44 patients with large intra- and suprasellar pituitary adenomas that were mainly hormonally inactive, intraoperative MR imaging allowed an ultra-early evaluation of tumor resection in 73% of cases; such an evaluation is normally only possible 2 to 3 months after surgery. A second intraoperative examination of 24 patients for suspected tumor remnants led to additional resection in 15 patients (34%).
Conclusions. Intraoperative MR imaging undoubtedly offers the option of a second look within the same surgical procedure, if incomplete tumor resection is suspected. Thus, the rate of procedures during which complete tumor removal is achieved can be improved. Furthermore, additional treatments for those patients in whom tumor removal was incomplete can be planned at an early stage, namely just after surgery.
Christopher I. Shaffrey and Justin S. Smith
Alex J. Koefman, Melissa Licari, Michael Bynevelt and Christopher R. P. Lind
An objective biomarker for pain is yet to be established. Functional MRI (fMRI) is a promising neuroimaging technique that may reveal an objective radiological biomarker. The purpose of this study was to evaluate fMRI technology in the setting of lumbosacral radiculopathy and discuss its application in revealing a biomarker for pain in the future.
A prospective, within-participant control study was conducted. Twenty participants with painful lumbosacral radiculopathy from intervertebral disc pathology were recruited. Functional imaging of the brain was performed during a randomly generated series of nonprovocative and provocative straight leg raise maneuvers.
With a statistical threshold set at p < 0.000001, 3 areas showed significant blood oxygen level–dependent (BOLD) signal change: right superior frontal gyrus (x = 2, y = 13, z = 48, k = 29, Brodmann area 6 [BA6]), left supramarginal cortex (x = −37, y = −44, z = 33, k = 1084, BA40), and left parietal cortex (x = −19, y = −41, z = 63, k = 354, BA5). With a statistical threshold set at p < 0.0002, 2 structures showed significant BOLD signal change: right putamen (x = 29, y = −11, z = 6, k = 72) and bilateral thalami (right: x = 23, y = −11, z = 21, k = 29; x = 8, y = −11, z = 9, k = 274; and left: x = −28, y = −32, z = 6, k = 21).
The results in this study compare with those in previous studies and suggest that fMRI technology can provide an objective assessment of the pain experience.