Congenital Spinal Cysts: An Update and Review of the Literature.

Congenital spinal cysts are rare and encompass a wide variety of diseases including arachnoid, enterogenous, teratomatous, neurenteric, foregut, bronchogenic, epithelial, ependymal, dermoid, and epidermoid cysts. Here, we elucidate the epidemiology, pathology, pathogenesis, and diagnostic findings of the most common congenital spinal cysts, followed by a discussion of their presentation and treatment options. Differentiating the cause of each lesion is crucial for targeted clinical and surgical management for the patient. Our review describes how arachnoid cysts can be observed, fenestrated, percutaneously drained, or shunted; however, the primary goal for neurenteric, dermoid, and epidermoid cysts is removal. Further, we discuss how patient presentation is dependent on the rate of growth and location of compression on the spinal cord and nerve roots. However, although many of these lesions are discovered incidentally on imaging, the spectrum of possible symptoms include pain, weakness, ataxia, bladder incontinence, and progressive or acute neurologic deficits. We present and review the histology and imaging of a variety of cysts and discuss how although the goal of treatment is resection, the risks of surgery must be considered against the benefits of complete resection in each case.

Deep Brain Electrode Externalization and Risk of Infection: A Systematic Review and Meta-Analysis.

BACKGROUND: When evaluating deep brain stimulation (DBS) for newer indications, patients may benefit from trial stimulation prior to permanent implantation or for investigatory purposes. Although several case series have evaluated infectious complications among DBS patients who underwent trials with external hardware, outcomes have been inconsistent. OBJECTIVE: To determine whether a period of lead externalization is associated with an increased risk of infection. METHODS: We conducted a Preferred Reporting Items for Systematic Reviews and Meta-Analyses compliant systematic review of all studies that included rates of infection for patients who were externalized prior to DBS implantation. A meta-analysis of proportions was performed to estimate the pooled proportion of infection across studies, and a meta-analysis of relative risks was conducted on those studies that included a control group of nonexternalized patients. Heterogeneity across studies was assessed via I2 index. RESULTS: Our search retrieved 23 articles, comprising 1354 patients who underwent lead externalization. The pooled proportion of infection was 6.9% (95% CI: 4.7%-9.5%), with a moderate to high level of heterogeneity between studies (I2 = 62.2%; 95% CI: 40.7-75.9; P < .0001). A total of 3 studies, comprising 212 externalized patients, included a control group. Rate of infection in externalized patients was 5.2% as compared to 6.0% in nonexternalized patients. However, meta-analysis was inadequately powered to determine whether there was indeed no difference in infection rate between the groups. CONCLUSION: The rate of infection in patients with electrode externalization is comparable to that reported in the literature for DBS implantation without a trial period. Future studies are needed before this information can be confidently used in the clinical setting.

Case Series: Deep Brain Stimulation for Facial Pain.

BACKGROUND: Deep brain stimulation (DBS) has been used for chronic pain for decades, but its use is limited due to a lack of reliable data about its efficacy for specific indications. OBJECTIVE: To report on 9 patients who underwent DBS for facial pain, with a focus on differences in outcomes between distinct etiologies. METHODS: We retrospectively reviewed 9 patients with facial pain who were treated with DBS of the ventral posteromedial nucleus of the thalamus and periventricular gray. We report on characteristics including facial pain etiology, complications, changes in pain scores using the visual analog scale (VAS), and willingness to undergo DBS again. RESULTS: Nine patients underwent DBS for either poststroke, post-traumatic, postherpetic, or atypical facial pain. Eight patients (89%) were permanently implanted. Seven patients had sufficient follow-up (mean 40.3 mo). Of these 7 patients, average VAS scores decreased from 9.4 to 6.1 after DBS. The average decrease in VAS was 55% for post-traumatic facial pain (2 patients), 45% for poststroke (2 patients), 15% for postherpetic neuralgia (2 patients), and 0% for atypical facial pain (1 patient). Three of the 8 implanted patients (38%) had complications which required removal of hardware. Only 2 of 7 (29%) patients met classical criteria for responders (50% decrease in pain scores). However, among 4 patients who were asked about willingness to undergo DBS again, all expressed that they would repeat the procedure. CONCLUSION: There is a trend towards improvement in pain scores following DBS for facial pain, most prominently with post-traumatic pain.

Symptomatic Pneumocephalus after Deep Brain Stimulation Surgery: Report of 2 Cases.

BACKGROUND: Symptomatic pneumocephalus is an uncommon complication of cranial surgery. Reports of symptomatic pneumocephalus in deep brain stimulation (DBS) surgery are lacking, due to the rarity of this condition. The -authors describe 2 patients who experienced clinically significant intraparenchymal pneumocephalus as a consequence of DBS surgery and report their clinical presentations, treatments, and outcomes. Cases Descriptions: The first patient was a 69-year-old woman with Parkinson disease and the second was a 73-year-old woman with medically refractory essential tremor. Both patients underwent DBS implantation and developed focal neurological deficits in the days after surgery. In each case, immediate postoperative head computed tomography scans showed extra-axial pneumocephalus which redistributed on subsequent imaging along the dorsal length of the lead. For each patient, a second surgery was carried out to evacuate the pneumocephalus without lead removal. Clinical symptoms and radiological signs of intracranial air were resolved on the last follow-up. CONCLUSION: Symptomatic intraparenchymal pneumocephalus is a rare complication of DBS surgery which can be treated with surgical evacuation.

Neurophysiological Monitoring During Arteriovenous Malformation Embolization.

BACKGROUND: Neurophysiological monitoring (NPM) is frequently performed during arteriovenous malformation (AVM) embolization. However, the ability of NPM to predict neurological deficits or improve surgical decision making in this setting has not been studied. OBJECTIVE: To review our use of NPM during AVM embolization to better define its utility. METHODS: We retrospectively examined AVM embolization cases from 2004 to 2017. We recorded patient and AVM characteristics as well as outcomes. We then reviewed NPM results from each case, including somatosensory evoked potentials and electroencephalogram. Our primary outcome was postoperative neurological deficit, and secondary outcomes were discharge and 30-d modified Rankin Score (mRS). RESULTS: There were 173 embolizations in 74 patients. Mean patient age was 40 yr. There were 8 (5%) transient and 2 (1.3%) permanent neurological complications. Among those with neurological complications, 3 had NPM changes during the operation (positive predictive value [PPV] = 50%). This improved to 67% for permanent NPM change. Three patients had NPM changes but did not suffer clinical deficits postoperatively (negative predictive value = 90%). The predictive value of the test was improved for discharge but not 30-d mRS, and the test performance improved dramatically with increased pretest probabilities (likelihood ratio [LR](+) = 14.5, LR(-) = 0.715). CONCLUSION: We present a large series of AVM embolization operations performed with NPM. The PPV of NPM changes was moderate but improved dramatically with increased pretest probabilities. The rate of permanent neurological complications was among the lowest reported in the literature, suggesting NPM may lead to improved intraoperative decision making.

The comparative accuracy of the ROSA stereotactic robot across a wide range of clinical applications and registration techniques.

Robot-assisted stereotactic neurosurgery is an emerging technology with a growing range of applications. The ROSA system is a robotic stereotactic system that has been shown to be accurate in laboratory studies and large case series. The goal of this study was to examine the accuracy of the ROSA across different registration methods as well as different clinical applications. Sixteen patients with one hundred and seventeen stereotactic trajectories were examined. Accuracy was compared by measuring the distance between the trajectory target and the actual termination of the device as determined by imaging. Entry error and angular deviation were also measured. Variables included bone fiducials vs. laser facial scanning, the clinical indication for stereotactic surgery, and the effect of lead deflection on accuracy. Bone fiducials did not offer an accuracy benefit over laser facial scanning (mean target error 4.5-3.9 mm, p = 0.34) in these clinical scenarios. Laser interstitial thermal therapy, responsive neurostimulation, and stereo electroencephalography were equally accurate when placed by the ROSA (mean target error 4.4-4.3-4.0 mm, respectively, p = 0.69). Deflection did not affect lead accuracy (mean target error 4.4-3.9 mm, p = 0.11). Similar results are seen for entry error and angular deviation. ROSA is a highly accurate stereotactic system. Laser facial scanning provides the same accuracy as bone fiducials in these stereotactic applications. The ROSA is equally accurate across a wide spectrum of applications. The ROSA is effective at limiting lead deflection, and when it does occur, it does not impact target accuracy in a significant way.

Robotic-Guided Bihippocampal and Biparahippocampal Depth Placement for Responsive Neurostimulation in Bitemporal Lobe Epilepsy.

BACKGROUND: Patients with bitemporal lobe epilepsy are generally not considered for surgical resection. Fortunately, responsive neurostimulation provides another avenue for the management of this challenging disease process. In conjunction with our epileptologist, we consider responsive neurostimulation for patients who have clinical features of temporal lobe epilepsy without clear localization on imaging and stereoelectroencephalography. METHODS: Here we describe our technique for implanting a responsive neurostimulator (NeuroPace, NeuroPace Inc., Mountain View, California) with depth electrodes monitoring the hippocampus and parahippocampus using stereotactic robotic guidance (ROSA, Medtech SA, Montpeillier, France). RESULTS: We have used this technique with 5 patients without morbidity. Four of 5 patients have received clinical benefit (Engel classification I-III). Promisingly, long-term seizure monitoring with use of the NeuroPace system has suggested lateralizing information on 3 of these patients that was not apparent on previous invasive monitoring. CONCLUSIONS: Robotically implanted responsive neurostimulation is a safe and effective treatment for bitemporal epilepsy and can possibly lead to valuable diagnostic information to guide future surgical management in patients who previously were not considered candidates for resective or ablative surgery.

Perioperative management of a neurosurgical patient requiring antiplatelet therapy.

In patients who undergo neurovascular stent placement with postoperative dual antiplatelet therapy to prevent in-stent thrombosis, there is no protocol for balancing the risk of acute stent thrombosis and bleeding if urgent neurosurgical procedures are required. We detail perioperative management of dual antiplatelet therapy in a 66-year-old man with a dolichoectatic aneurysm of the basilar artery treated with a Pipeline stent. Postoperatively, the patient was placed on aspirin and clopidogrel to prevent in-stent thrombosis. One month after the procedure, his neurological status declined secondary to obstructive hydrocephalus. His condition necessitated urgent placement of a ventriculoperitoneal shunt, despite the dual antiplatelet therapy for the flow-diverting Pipeline stent. Aspirin and clopidogrel were discontinued seven days prior to the planned shunt placement. To minimize time off antiplatelet therapy, aspirin was immediately replaced with ibuprofen. Eptifibatide was then started three days prior to surgery. The ibuprofen/eptifibatide bridge was discontinued at midnight prior to surgery. Aspirin was restarted on the first postoperative day and clopidogrel was restarted on the second postoperative day. The patient tolerated shunt placement without excessive bleeding or hemorrhagic complications. During the remainder of his hospital course, no evidence of stent thrombosis or intracranial hemorrhage was noted. We conclude that management of antiplatelet prophylaxis for neurovascular stent thrombosis in patients requiring urgent neurosurgical procedures may be successfully achieved by bridging aspirin and clopidogrel with ibuprofen and eptifibatide in the preoperative period.

In vivo performance of a microelectrode neural probe with integrated drug delivery.

OBJECT: The availability of sophisticated neural probes is a key prerequisite in the development of future brain-machine interfaces (BMIs). In this study, the authors developed and validated a neural probe design capable of simultaneous drug delivery and electrophysiology recordings in vivo. Focal drug delivery promises to extend dramatically the recording lives of neural probes, a limiting factor to clinical adoption of BMI technology. METHODS: To form the multifunctional neural probe, the authors affixed a 16-channel microfabricated silicon electrode array to a fused silica catheter. Three experiments were conducted in rats to characterize the performance of the device. Experiment 1 examined cellular damage from probe insertion and the drug distribution in tissue. Experiment 2 measured the effects of saline infusions delivered through the probe on concurrent electrophysiological measurements. Experiment 3 demonstrated that a physiologically relevant amount of drug can be delivered in a controlled fashion. For these experiments, Hoechst and propidium iodide stains were used to assess insertion trauma and the tissue distribution of the infusate. Artificial CSF (aCSF) and tetrodotoxin (TTX) were injected to determine the efficacy of drug delivery. RESULTS: The newly developed multifunctional neural probes were successfully inserted into rat cortex and were able to deliver fluids and drugs that resulted in the expected electrophysiological and histological responses. The damage from insertion of the device into brain tissue was substantially less than the volume of drug dispersion in tissue. Electrophysiological activity, including both individual spikes as well as local field potentials, was successfully recorded with this device during real-time drug delivery. No significant changes were seen in response to delivery of aCSF as a control experiment, whereas delivery of TTX produced the expected result of suppressing all spiking activity in the vicinity of the catheter outlet. CONCLUSIONS: Multifunctional neural probes such as the ones developed and validated within this study have great potential to help further understand the design space and criteria for the next generation of neural probe technology. By incorporating integrated drug delivery functionality into the probes, new treatment options for neurological disorders and regenerative neural interfaces using localized and feedback-controlled delivery of drugs can be realized in the near future.

Characterizing radial undersampling artifacts for cardiac applications.

The undersampled radial acquisition has been widely employed for accelerated (by a factor R = N(r)/N(p)) cardiac imaging, but the resulting reduction in image quality has not been well characterized. This investigation presents a method of measuring these artifacts through synthetic undersampling of high SNR images (SNR > or = 30). After validating the method in phantoms, the method was applied to a study of short-axis, long-axis, and coronary MRI imaging in healthy subjects. For 60 projections (60 N(p)), the total artifact is approximately 10% for short and long-axis imaging (R = 2.1) and approximately 15% for coronary MRI (R = 3.7). For 60 N(p), the SD of artifact in the region of the heart is 2% for short- and long-axis imaging (R = 2.1) and 3.5% for coronary MRI (R = 3.7). The artifact content is less in the region of the heart than in the periphery. The artifact is very reproducible among subjects for standard views. A study of coronary MRI at progressively fewer projections (at constant scan time) showed that right coronary MRI images were acceptable if total artifact was <6.5% of image content (N(p) > 120, R = 2.1).

3D breath-held cardiac function with projection reconstruction in steady state free precession validated using 2D cine MRI.

PURPOSE: To develop and validate a three-dimensional (3D) single breath-hold, projection reconstruction (PR), balanced steady state free precession (SSFP) method for cardiac function evaluation against a two-dimensional (2D) multislice Fourier (Cartesian) transform (FT) SSFP method. MATERIALS AND METHODS: The 3D PR SSFP sequence used projections in the x-y plane and partitions in z, providing 70-80 msec temporal resolution and 1.7 x 1.7 x 8-10 mm in a 24-heartbeat breath hold. A total of 10 volunteers were imaged with both methods, and the measurements of global cardiac function were compared. RESULTS: Mean signal-to-noise ratios (SNRs) for the blood and myocardium were 114 and 42 (2D) and 59 and 21 (3D). Bland-Altman analysis comparing the 2D and 3D ejection fraction (EF), left ventricular end diastolic volume (LVEDV) and end systolic volume (LVESV), and end diastolic myocardial mass (LVEDM) provided values of bias +/-2 SD of 0.6% +/- 7.7 % for LVEF, 5.9 mL +/- 20 mL for LVEDV, -2.8 mL +/- 12 mL for LVESV, and -0.61 g +/- 13 g for LVEDM. 3D interobserver variability was greater than 2D for LVEDM and LVESV. CONCLUSION: In a single breath hold, the 3D PR method provides comparable information to the standard 2D FT method, which employs 10-12 breath holds.

Complementation of bacteriophage induction and recombination defects in Escherichia coli RecA(-) mutants by expression of the cloned T4 bacteriophage uvsX gene.

Previous workers reported that the T4 bacteriophage UvsX protein could promote neither RecA-LexA-mediated DNA repair nor induction of lysogenized bacteriophage, only recombination. Reexamination of these phenotypes demonstrated that, in contrast to these prior studies, when this gene was cloned into a medium but not a low-copy-number vector, it stimulated both a high frequency of spontaneous induction and mitomycin C-stimulated bacteriophage induction in a strain containing a recA13 mutation, but not a recA1 defect. The gene when cloned into a low- or medium- copy-number vector also promoted a low frequency of recombination of two duplicated genes in Escherichia coli in a strain with a complete recA gene deletion. These results suggest that a narrow concentration range of T4 UvsX protein is required to promote both high-frequency spontaneous and mitomycin C-stimulated bacteriophage induction in a recA13 gene mutant, but it facilitates recombination of duplicated genes at only a very low frequency in E. coli RecA(-) mutants with a complete recA deletion. These results also suggest that the different UvsX phenotypes are affected differentially by the concentration of UvsX protein present.