Implantable Subdural Cortical Stimulation for Chronic Intractable Pain Treatment-The Mayo Experience and Review of Literature

OBJECTIVES

Motor cortex stimulation (MCS) is an effective technique in treating chronic intractable pain for some patients. However, most studies are small case series (n < 20). Heterogeneity in technique and patient selection makes it difficult to draw consistent conclusions. In this study, we present one of the largest case series of subdural MCS.

MATERIALS AND METHODS

Medical records of patients who underwent MCS at our institute between 2007 and 2020 were reviewed. Studies with at least 15 patients were summarized for comparison.

RESULTS

The study included 46 patients. Mean age was 56.2 ± 12.5 years (SD). Mean follow-up was 57.2 ± 41.9 months. Male-to-female ratio was 13:33. Of the 46 patients, 29 had neuropathic pain in trigeminal nerve territory/anesthesia dolorosa; nine had postsurgical/posttraumatic pain; three had phantom limb pain; two had postherpetic pain, and the rest had pain secondary to stroke, chronic regional pain syndrome, and tumor. The baseline numeric rating pain scale (NRS) was 8.2 ± 1.8 of 10, and the latest follow-up score was 3.5 ± 2.9 (mean improvement of 57.3%). Responders comprised 67% (31/46)(NRS ≥ 40% improvement). Analysis showed no correlation between percentage of improvement and age (p = 0.352) but favored male patients (75.3% vs 48.7%, p = 0.006). Seizures occurred in 47.8% of patients (22/46) at some point but were all self-limiting, with no lasting sequelae. Other complications included subdural/epidural hematoma requiring evacuation (3/46), infection (5/46), and cerebrospinal fluid leak (1/46). These complications resolved with no long-term sequelae after further interventions.

CONCLUSION

Our study further supports the use of MCS as an effective treatment modality for several chronic intractable pain conditions and provides a benchmark to the current literature.

Results of surgical resection of carotid body tumors: A twenty-year experience

This study examines whether surgical resection of carotid body tumors (CBTs) is acceptable in light of potential significant neurologic complications. This IRB-approved retrospective study analyzed data from 24 patients undergoing surgical treatment for CBTs between April 1998 and April 2017 at Mayo Clinic (Florida campus only). For patients who underwent multiple CBT resections, only data from the first surgery was used in this analysis. CBT resection occurred in 24 patients with the following demographics: fourteen patients (58.3%) were female, median age was 56.5 years, median BMI was 29. A prior history of neoplasm was found in ten patients (41.7%). A known family history of paraganglioma was present in five patients (20.8%). Two patients were positive for succinate dehydrogenase mutation (8.3%). Multiple paragangliomas were present in seven patients (29.2%). There was nerve sacrifice in three patients (12.5%) during resection. Carotid artery reconstruction and patch angioplasty occurred in one patient (4.2%). Complete resection occurred in 24 patients (100.0%). Postoperatively, one patient (4.2%) suffered stroke. No mortalities occurred within or beyond 30 days of surgery. Persistent cranial nerve injury occurred in two patients (8.3%) with vocal cord paralysis. There was no recurrence of CBT through last follow-up. Five patients (20.8%) were diagnosed with other neoplasms after resection, including basal cell carcinoma, contralateral carotid body tumor, glomus vagale, and glomus jugulare. There was 100% survival at 1 year in patients followed for that time (n = 17). Surgical treatment remains the first-line curative treatment to relieve symptoms and ensure non-recurrence. While acceptable, neurologic complications are significant and therefore detailed preoperative informed consent is mandatory.

Outcomes following surgical management of vagus nerve stimulator-related infection: a retrospective multi-institutional study

OBJECTIVE

Surgical site infection (SSI) is a rare but significant complication after vagus nerve stimulator (VNS) placement. Treatment options range from antibiotic therapy alone to hardware removal. The optimal therapeutic strategy remains open to debate. Therefore, the authors conducted this retrospective multicenter analysis to provide insight into the optimal management of VNS-related SSI (VNS-SSI).

METHODS

Under institutional review board approval and utilizing an institutional database with 641 patients who had undergone 808 VNS-related placement surgeries and 31 patients who had undergone VNS-related hardware removal surgeries, the authors retrospectively analyzed VNS-SSI.

RESULTS

Sixteen cases of VNS-SSI were identified; 12 of them had undergone the original VNS placement procedure at the authors' institutions. Thus, the incidence of VNS-SSI was calculated as 1.5%. The mean (± standard deviation) time from the most recent VNS-related surgeries to infection was 42 (± 27) days. Methicillin-sensitive staphylococcus was the usual causative bacteria (58%). Initial treatments included antibiotics with or without nonsurgical procedures (n = 6), nonremoval open surgeries for irrigation (n = 3), generator removal (n = 3), and total or near-total removal of hardware (n = 4). Although 2 patients were successfully treated with antibiotics alone or combined with generator removal, removal of both the generator and leads was eventually required in 14 patients. Mild swallowing difficulties and hoarseness occurred in 2 patients with eventual resolution.

CONCLUSIONS

Removal of the VNS including electrode leads combined with antibiotic administration is the definitive treatment but has a risk of causing dysphagia. If the surgeon finds dense scarring around the vagus nerve, the prudent approach is to snip the electrode close to the nerve as opposed to attempting to unwind the lead completely.

In NPH, setting valve opening pressure close to lumbar puncture opening pressure decreases overdrainage

BACKGROUND

The management of normal pressure hydrocephalus (NPH) can be difficult, partly because there are frequent treatment complications such as overdrainage which, when serious, may require surgical intervention. We previously reported a correlation between the difference of lumbar puncture opening pressure minus the valve opening pressure setting (LPOP-VOP) (which we refer to as the delta) and increased rates of overdrainage. This led to a modification in our practice, whereby we now set the VOP equal to, or close to, the LPOP, resulting in lower deltas.

OBJECTIVE

In this new study, our aim was to compare the rate of overdrainage in our patients with higher and lower deltas and assess the significance of setting the VOP equal, or close, to the patient's LPOP.

METHODS

1. We reproduced the association between delta and overdrainage. 2. We compared the incidence of overdrainage in those whose VOP was set close to LPOP (low delta) versus those with VOP setting distant from the LPOP (higher delta). 3. We compared symptom improvement in those with a low versus higher delta.

RESULTS

We confirmed the relation between high delta and an increased rate of overdrainage, lower rates of overdrainage in those whose VOP was set close to the LPOP (Delta Adjusted Practice), and better improvement of symptoms when the VOP was set closer to the LPOP.

CONCLUSION

We propose that the initial VOP should be set as close as possible to the patient's LPOP to decrease overdrainage without compromising symptom improvement.

Nine-year prospective efficacy and safety of brain-responsive neurostimulation for focal epilepsy

OBJECTIVE

To prospectively evaluate safety and efficacy of brain-responsive neurostimulation in adults with medically intractable focal onset seizures (FOS) over 9 years.

METHODS

Adults treated with brain-responsive neurostimulation in 2-year feasibility or randomized controlled trials were enrolled in a long-term prospective open label trial (LTT) to assess safety, efficacy, and quality of life (QOL) over an additional 7 years. Safety was assessed as adverse events (AEs), efficacy as median percent change in seizure frequency and responder rate, and QOL with the Quality of Life in Epilepsy (QOLIE-89) inventory.

RESULTS

Of 256 patients treated in the initial trials, 230 participated in the LTT. At 9 years, the median percent reduction in seizure frequency was 75% (p < 0.0001, Wilcoxon signed rank), responder rate was 73%, and 35% had a ≥90% reduction in seizure frequency. We found that 18.4% (47 of 256) experienced ≥1 year of seizure freedom, with 62% (29 of 47) seizure-free at the last follow-up and an average seizure-free period of 3.2 years (range 1.04-9.6 years). Overall QOL and epilepsy-targeted and cognitive domains of QOLIE-89 remained significantly improved (p < 0.05). There were no serious AEs related to stimulation, and the sudden unexplained death in epilepsy (SUDEP) rate was significantly lower than predefined comparators (p < 0.05, 1-tailed χ2).

CONCLUSIONS

Adjunctive brain-responsive neurostimulation provides significant and sustained reductions in the frequency of FOS with improved QOL. Stimulation was well tolerated; implantation-related AEs were typical of other neurostimulation devices; and SUDEP rates were low.

CLINICALTRIALSGOV IDENTIFIER

NCT00572195.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that brain-responsive neurostimulation significantly reduces focal seizures with acceptable safety over 9 years.

Neuroimaging Advances in Deep Brain Stimulation: Review of Indications, Anatomy, and Brain Connectomics

Deep brain stimulation is an established therapy for multiple brain disorders, with rapidly expanding potential indications. Neuroimaging has advanced the field of deep brain stimulation through improvements in delineation of anatomy, and, more recently, application of brain connectomics. Older lesion-derived, localizationist theories of these conditions have evolved to newer, network-based "circuitopathies," aided by the ability to directly assess these brain circuits in vivo through the use of advanced neuroimaging techniques, such as diffusion tractography and fMRI. In this review, we use a combination of ultra-high-field MR imaging and diffusion tractography to highlight relevant anatomy for the currently approved indications for deep brain stimulation in the United States: essential tremor, Parkinson disease, drug-resistant epilepsy, dystonia, and obsessive-compulsive disorder. We also review the literature regarding the use of fMRI and diffusion tractography in understanding the role of deep brain stimulation in these disorders, as well as their potential use in both surgical targeting and device programming.

Variability Between Direct and Indirect Targeting of the Anterior Nucleus of the Thalamus

BACKGROUND

Preoperative thalamic targeting methods have historically relied on indirect targeting techniques that do not fully account for variances in anatomy or for thalamic atrophy in epilepsy. We aimed to address variability noted between traditional indirect targeting and direct targeting methods for the anterior nucleus of the thalamus (ANT).

METHODS

Fifteen consecutive patients undergoing ANT deep brain stimulator placement were evaluated (30 thalamic nuclei). Direct ANT targeting was performed using a fast gray matter acquisition T1 inversion recovery sequence and compared with standard stereotactic coordinates. Thalamic volumes were calculated for each patient, and degree of thalamic volume loss was assessed compared with matched control subjects. Vertex analysis was performed to assess shape changes in the thalamus compared with age- and sex-matched subjects.

RESULTS

There was significant variation between direct and indirect targets in the y-axis and z-axis on both sides. On the left, the direct target was located at y = 2 ± 1.3 mm and z = 9.3 ± 1.8 mm (both P = 0.02). On the right, the direct target was located at y = 2.9 ± 1.8 mm and z = 9.2 ± 2 mm (both P ≤ 0.0003). There was no significant difference in the x-coordinate on either side (P > 0.5). Additionally, there was a correlation between thalamic volume and difference between direct and indirect targets in the y-axis and the z-axis.

CONCLUSIONS

We showed a significant difference in direct and indirect targeting in the y-axis and z-axis when targeting the ANT for deep brain stimulation for epilepsy. This difference is correlated to thalamic volume, with a larger difference noted in patients with thalamic atrophy.

The reliability of Deep Brain Stimulation YouTube videos

BACKGROUND

Deep Brain Stimulation (DBS) was approved by the FDA in the 1990s and is used to treat a variety of movement disorders. Patients are increasingly turning to the internet for information regarding their ailments. In this study, we aim to evaluate the accuracy and reliability of information presented in DBS-related YouTube videos.

METHODS

Using the "Relevance-Based Ranking" strategy for analysis we assessed the first 3 pages of YouTube for each of the following keywords: "Deep Brain Stimulation", "DBS", "DBS for Parkinson's disease", "DBS for essential tremor", and "DBS for movement disorders". Four independent healthcare personnel evaluated the videos' education quality and informational material using the validated DISCERN tool.

RESULTS

Our study found that only 24% of the 42 published videos analyzed scored above a 3 on the DISCERN scoring scale (considered a "good" video). The search term "Deep Brain Stimulation" had the highest percentage of good videos (DISCERN > 3) (32%). We also found that the duration of videos was longer for the "good" videos (Good = 25.6 min vs Unhelpful = 3.0 min, P = 0.01).

CONCLUSION

YouTube is one of the largest video platforms; the uploaded videos lack reliability and institutional oversight by the experts. We believe that medical institutions should explore this way of communicating to patients by publishing evidence-based and informative videos on diseases and their management. As it is imperative that the medical field advance to combat medical misinformation.

Video-Assisted Bilateral Thoracoscopic Sympathotomy for Palmar Hyperhidrosis

In this video, we demonstrate a case of a 21-year-old right-handed man who presented with palmar hyperhidrosis. His symptoms started at the age of 4 years and progressively worsened throughout his life. Multiple medical treatments were used without significant benefit. His symptoms worsened to the limit that it affected his work and lifestyle. The patient was taken to the operating room in a supine position with both arms abducted 90°. The right and left chest were prepped and draped in a sterile fashion. The skin incision was done on the left side first, the left lung was isolated, and two 5-mm thoracoports were placed in the sixth and third intercostal spaces, respectively. Carbon dioxide insufflation was used to a pressure of 6 mm Hg for exposure. The chest was visualized, and the sympathetic chain was identified. Ribs were counted and then cautery at a low setting was used. The sympathetic chain was transected at the level of the head of the second rib. Accessory nerves of Kuntz were identified and resected. Carbon dioxide was then evacuated from the left chest using a bronchial tube exchanger and Valsalva maneuver. The lung was completely reinflated and skin was closed in a normal fashion. The same procedure was repeated on the right side. A chest radiograph was obtained intraoperatively, and no pneumothorax was observed. At the end of the procedure, both upper extremity temperature probes showed a significant increase from baseline. Informed patient consent was obtained.

De novo temporal intermittent rhythmic delta activity after laser interstitial thermal therapy for mesial temporal lobe epilepsy predicts poor seizure outcome

OBJECTIVE

To evaluate EEG abnormalities, particularly development of temporal intermittent rhythmic delta activity (TIRDA) after laser interstitial thermal therapy (LITT) and assess the role of further surgery after LITT.

METHODS

We retrospectively identified consecutive cases of LITT for the prevalence of post-operative TIRDA. We assessed baseline demographics, clinical variables including age of seizure onset, age at surgery, pre-operative and post-operative EEG changes.

RESULTS

40 patients underwent LITT for drug-resistant temporal lobe epilepsy (TLE), 29 met inclusion criteria. Median duration of follow-up was 15 months. Ten patients had post-LITT ipsilateral TIRDA, another two demonstrated post-operative TIRDA but they occurred contralateral to the side of ablation. None of the patients with TIRDA on their post-LITT EEG became seizure-free. Six out of 29 patients (21%) eventually required anterior temporal lobectomy (ATL), and of those 6 patients 4 (66%) had evidence of TIRDA on their post-LITT follow up EEG. The sensitivity and specificity of post-LITT TIRDA in predicting surgical failure was 57.14% and 100% respectively.

CONCLUSIONS

Post-LITT TIRDA may serve as a biomarker to predict unsuccessful seizure outcome following LITT and be an early indicator for ATL.

SIGNIFICANCE

The presence of TIRDA following LITT should prompt early consideration for reoperation.

Laser ablation for mesial temporal epilepsy: a multi-site, single institutional series

OBJECTIVEAlthough it is still early in its application, laser interstitial thermal therapy (LiTT) has increasingly been employed as a surgical option for patients with mesial temporal lobe epilepsy. This study aimed to describe mesial temporal lobe ablation volumes and seizure outcomes following LiTT across the Mayo Clinic's 3 epilepsy surgery centers.METHODSThis was a multi-site, single-institution, retrospective review of seizure outcomes and ablation volumes following LiTT for medically intractable mesial temporal lobe epilepsy between October 2011 and October 2015. Pre-ablation and post-ablation follow-up volumes of the hippocampus were measured using FreeSurfer, and the volume of ablated tissue was also measured on intraoperative MRI using a supervised spline-based edge detection algorithm. To determine seizure outcomes, results were compared between those patients who were seizure free and those who continued to experience seizures.RESULTSThere were 23 patients who underwent mesial temporal LiTT within the study period. Fifteen patients (65%) had left-sided procedures. The median follow-up was 34 months (range 12-70 months). The mean ablation volume was 6888 mm3. Median hippocampal ablation was 65%, with a median amygdala ablation of 43%. At last follow-up, 11 (48%) of these patients were seizure free. There was no correlation between ablation volume and seizure freedom (p = 0.69). There was also no correlation between percent ablation of the amygdala (p = 0.28) or hippocampus (p = 0.82) and seizure outcomes. Twelve patients underwent formal testing with computational visual fields. Visual field changes were seen in 67% of patients who underwent testing. Comparing the 5 patients with clinically noticeable visual field deficits to the rest of the cohort showed no significant difference in ablation volume between those patients with visual field deficits and those without (p = 0.94). There were 11 patients with follow-up neuropsychological testing. Within this group, verbal learning retention was 76% in the patients with left-sided procedures and 89% in those with right-sided procedures.CONCLUSIONSIn this study, there was no significant correlation between the ablation volume after LiTT and seizure outcomes. Visual field deficits were common in formally tested patients, much as in patients treated with open temporal lobectomy. Further studies are required to determine the role of amygdalohippocampal ablation.

Surgical treatment of bilateral glossopharyngeal neuralgia

Glossopharyngeal neuralgia (GPN) is a condition characterised by sudden, severe pain in the distribution of the glossopharyngeal nerve. It can be triggered by talking, yawning, coughing and swallowing. Classically, patients experience a unilateral lancinating and excruciating pain described as electrical shock-like pain in the areas around the ear, tongue, or the mandibular angle. Uncommon manifestations include cardiac arrhythmias and syncope during pain episodes. Surgery is indicated in refractory cases. Bilateral GPN is rare, and definitive surgical treatment for bilateral GPN has not yet been reported. In this case report, a young woman with bilateral GPN who underwent staged surgery bilaterally is described. She did not develop life-threatening cardiac abnormalities postoperatively.

Nonaneurysmal "Pseudo-Subarachnoid Hemorrhage" Computed Tomography Patterns: Challenges in an Acute Decision-Making Heuristics

BACKGROUND

Acute aneurysmal subarachnoid hemorrhage (SAH) is a medical and neurosurgical emergency from ruptured brain aneurysm. Aneurysmal SAH is identified on brain computed tomography (CT) as increased density of basal cisterns and subarachnoid spaces from acute blood products. Aneurysmal SAH-like pattern on CT appears as an optical illusion effect of hypodense brain parenchyma and/or hyperdense surrounding cerebral cisterns and blood vessels termed as "pseudo-subarachnoid hemorrhage" (pseudo-SAH).

METHODS

We reviewed clinical, laboratory, and radiographic data of all SAH diagnoses between January 2013 and January 2018, and found subsets of nonaneurysmal SAH, originally suspected to be aneurysmal in origin. We performed a National Library of Medicine search methodology using terms "subarachnoid hemorrhage," "pseudo," and "non-aneurysmal subarachnoid hemorrhage" singly and in combination to understand the sensitivity, specificity, and precision of pseudo-SAH.

RESULTS

Over 5 years, 230 SAH cases were referred to our tertiary academic center and only 7 (3%) met the definition of pseudo-SAH. Searching the National Library of Medicine using subarachnoid hemorrhage yielded 27,402 results. When subarachnoid hemorrhage and pseudo were combined, this yielded 70 results and sensitivity was 50% (n = 35). Similarly, search precision was relatively low (26%) as only 18 results fit the clinical description similar to the 7 cases discussed in our series.

CONCLUSIONS

Aneurysmal SAH pattern on CT is distinct from nonaneurysmal and pseudo-SAH patterns. The origin of pseudo-SAH terminology appears mostly tied to comatose cardiac arrest patients with diffuse dark brain Hounsfield units and cerebral edema, and is a potential imaging pitfall in acute medical decision-making.

The impact of stereotactic laser ablation at a typical epilepsy center

PURPOSE

Stereotactic laser ablation (SLA) is a novel form of epilepsy surgery for patients with drug-resistant focal epilepsy. We evaluated one hundred consecutive surgeries performed for patients with epilepsy to address the impact of SLA on our therapeutic approach, as well as patient outcomes.

METHODS

A retrospective, single center analysis of the last one hundred neurosurgeries for epilepsy was performed from 2013 to 2015. Demographics, surgical procedures, and postoperative measures were assessed up to 5years to compare the effect of SLA on outcome. Confidence intervals (CI) and comparative tests of proportions compared outcomes for SLA and resective surgery. Procedural categorical comparison used Chi-square and Kaplan-Meier curves. Student t-test was utilized for single variables such as age at procedure and seizure onset.

RESULTS

One hundred surgeries for epilepsy yielded thirty-three SLAs and twenty-one resections with a mean of 21.7-month and 21.3-month follow-up, respectively. The temporal lobe was the most common target for SLA (92.6%) and resection (75%). A discrete lesion was present on brain magnetic resonance imaging (MRI) in 27/32 (84.4%) of SLA patients compared with 7/20 (35%) of resection patients with a normal MRI. Overall, 55-60% of patients became seizure-free (SF). Four of five patients with initial failure to SLA became SF with subsequent resection surgery. Complications were more frequent with resection although SF outcomes did not differ (Chi square; p=0.79). Stereotactic laser ablation patients were older than those with resections (47.0years vs. 35.4years, p=0.001). The mean length of hospitalization prior to discharge was shorter for SLA (1.18days) compared with open resection (3.43days; SD: 3.16 days) (p=0.0002).

CONCLUSION

We now use SLA as a first line therapy at our center in patients with lesional temporal lobe epilepsy (TLE) before resection. Seizure-free outcome with SLA and resection was similar but with a shorter length of stay. Long-term follow-up is recommended to determine sustained SF status from SLA.

Neuropsychological outcomes following stereotactic laser amygdalohippocampectomy

OBJECTIVE

The objective was to analyze neuropsychological testing data from 15 patients before and after stereotactic laser ablation surgery for temporal lobe epilepsy and to describe the seizure outcomes after stereotactic laser ablation surgery.

METHODS

A retrospective review of 15 patients who underwent stereotactic laser ablation and who also underwent neuropsychological testing before and after surgery was performed. Verbal and visual memory was assessed in all 15 patients using California Verbal Learning Test and Wechsler Memory Scale IV. Naming was assessed in 9 of 15 patients using the Boston Naming Test. Statistical analysis was performed to determine clinically significant changes using previously validated reliable change indices and proprietary Advanced Clinical Solutions software. Seizure outcome data were evaluated using Engel classification.

RESULTS

Postsurgery neuropsychological evaluation demonstrated that all 15 patients experienced at least 1 clinically significant decline in either verbal or visual memory. Ten patients in this series, including five with dominant-hemisphere surgery, demonstrated decline in delayed memory for narrative information (Logical Memory II). By contrast, the Boston Naming Test demonstrated more favorable results after surgery. Two of nine patients demonstrated a clinically significant increase in naming ability, and only one of nine patients demonstrated a clinically significant decline in naming ability. With at least 6months of follow-up after surgery, 33% reported seizure freedom.

CONCLUSION

Stereotactic laser ablation can result in clinically significant and meaningful decline in verbal and visual memory when comparing patients to their own presurgical baseline. Naming ability, conversely, is much less likely to be impacted by stereotactic laser ablation and may improve after the procedure.

Multivalent bi-specific nanobioconjugate engager for targeted cancer immunotherapy

Tumour-targeted immunotherapy offers the unique advantage of specific tumouricidal effects with reduced immune-associated toxicity. However, existing platforms suffer from low potency, inability to generate long-term immune memory and decreased activities against tumour-cell subpopulations with low targeting receptor levels. Here we adopted a modular design approach that uses colloidal nanoparticles as substrates to create a multivalent bi-specific nanobioconjugate engager (mBiNE) to promote selective, immune-mediated eradication of cancer cells. By simultaneously targeting the human epidermal growth factor receptor 2 (HER2) expressed by cancer cells and pro-phagocytosis signalling mediated by calreticulin, the mBiNE stimulated HER2-targeted phagocytosis and produced durable antitumour immune responses against HER2-expressing tumours. Interestingly, although the initial immune activation mediated by the mBiNE was receptor dependent, the subsequent antitumour immunity also generated protective effects against tumour-cell populations that lacked the HER2 receptor. Thus, the mBiNE represents a new targeted, nanomaterial-immunotherapy platform to stimulate innate and adaptive immunity and promote a universal antitumour response.

Thalamic DBS with a constant-current device in essential tremor: A controlled clinical trial

INTRODUCTION

This study of thalamic deep brain stimulation (DBS) investigated whether a novel constant-current device improves tremor and activities of daily living (ADL) in patients with essential tremor (ET).

METHODS

A prospective, controlled, multicenter study was conducted at 12 academic centers. We investigated the safety and efficacy of unilateral and bilateral constant-current DBS of the ventralis intermedius (VIM) nucleus of the thalamus in patients with essential tremor whose tremor was inadequately controlled by medications. The primary outcome measure was a rater-blinded assessment of the change in the target limb tremor score in the stimulation-on versus stimulation-off state six months following surgery. Multiple secondary outcomes were assessed at one-year follow-up, including motor, mood, and quality-of-life measures.

RESULTS

127 patients were implanted with VIM DBS. The blinded, primary outcome variable (n = 76) revealed a mean improvement of 1.25 ± 1.26 points in the target limb tremor rating scale (TRS) score in the arm contralateral to DBS (p < 0.001). Secondary outcome variables at one year revealed significant improvements (p ≤ 0.001) in quality of life, depression symptoms, and ADL scores. Forty-seven patients had a second contralateral VIM-DBS, and this group demonstrated reduction in second-sided tremor at 180 days (p < 0.001). Serious adverse events related to the surgery included infection (n = 3), intracranial hemorrhage (n = 3), and device explantation (n = 3).

CONCLUSION

Unilateral and bilateral constant-current VIM DBS significantly improves upper extremity tremor, ADL, quality of life, and depression in patients with severe ET.

Deep brain stimulation for levodopa-refractory benign tremulous parkinsonism

Benign tremulous parkinsonism (BTP) is characterized by prominent resting tremor combined with action and postural components, and with only subtle rigidity and bradykinesia. This tremor is frequently disabling and poorly responsive to therapy with levodopa. Thus, BTP could be considered either as a distinct clinical disorder or a variant of PD. We present a case of a 57-year-old man who had a 3-year history of severe and functionally disabling resting tremor with action and postural features bilaterally but with left dominant hand predominance. There was only very mild rigidity and bradykinesia and no postural instability. His tremor was refractory to dopaminergic therapy, including carbidopa/levodopa. The dopamine transporter (DAT) imaging showed reduced tracer uptake in the putamen bilaterally, more so on the right side. He was treated with deep brain stimulation (DBS) targeting the right ventral intermediate nucleus of the thalamus. His tremor resolved immediately after procedure. The DAT imaging abnormalities indicate the presynaptic dopamine deficiency. In some autopsied BTP cases classic alpha-synuclein pathology of PD was observed. Thus, despite the lack of levodopa responsiveness BTP likely represents a variant of PD and not a distinct neurodegenerative disorder. DBS should be considered for patients with BTP PD variant despite their poor responsiveness to levodopa treatment.

Surface modification of nanoparticles enables selective evasion of phagocytic clearance by distinct macrophage phenotypes

Nanomedicine is a burgeoning industry but an understanding of the interaction of nanomaterials with the immune system is critical for clinical translation. Macrophages play a fundamental role in the immune system by engulfing foreign particulates such as nanoparticles. When activated, macrophages form distinct phenotypic populations with unique immune functions, however the mechanism by which these polarized macrophages react to nanoparticles is unclear. Furthermore, strategies to selectively evade activated macrophage subpopulations are lacking. Here we demonstrate that stimulated macrophages possess higher phagocytic activities and that classically activated (M1) macrophages exhibit greater phagocytic capacity than alternatively activated (M2) macrophages. We show that modification of nanoparticles with polyethylene-glycol results in decreased clearance by all macrophage phenotypes, but importantly, coating nanoparticles with CD47 preferentially lowers phagocytic activity by the M1 phenotype. These results suggest that bio-inspired nanoparticle surface design may enable evasion of specific components of the immune system and provide a rational approach for developing immune tolerant nanomedicines.

Non-contiguous meningeal metastases of olfactory neuroblastoma

Olfactory neuroblastoma (ONB) is a malignant neoplasm centered along the roof of the nasal cavity near the cribriform plate. Although metastasis of this tumor has been reported, non-contiguous spread to the dura is rare. Here, we report the largest series of intracranial meningeal metastases of ONBs from M.D. Anderson Cancer Center and the University of Toronto. The unique natural history and geographical distribution of these metastatic lesions suggest a common mechanism of tumor spread along the dural vascular arborization.

Influence of body mass index and age on functional outcomes in patients with subarachnoid hemorrhage

BACKGROUND

Recent studies have highlighted the obesity paradox where patients with obesity have a greater chance of survival than patients with normal weight.

OBJECTIVE

To investigate the association between body mass index (BMI) and age with severity of subarachnoid hemorrhage (SAH) and functional outcome.

METHODS

We retrospectively reviewed the charts of 274 consecutive patients admitted with SAH between June 2008 and June 2012. Data collected included patient demographic features (age, sex, BMI), severity of SAH at admission (Fisher grade, Hunt and Hess grade, Glasgow Coma Scale score, and the World Federation of Neurosurgeons Scale score), as well as functional outcome measured by the modified Rankin Scale (mRS) by death or discharge.

RESULTS

The median age was 57 years (range, 18-99), and 62% were female; the median BMI was 27 (range, 14.3-55.1). On multivariate analysis adjusting for age and sex, there was no evidence of an association between BMI and Hunt and Hess grade, Fisher grade, World Federation of Neurosurgeons Scale score, Glasgow Coma Scale score, or mRS score (all P≥.17). On multivariate analysis adjusting for BMI and sex, there was evidence of a higher mRS score (P<.001) and lower WFNS grade (P=.016) in older patients, with no significant association observed between age and the remaining 3 measures of SAH severity (all P≥.10).

CONCLUSION

The results of our study indicate that BMI is not noticeably associated with severity of bleeding or functional outcome in patients with SAH. This finding was discovered after performing a multivariate analysis adjusting for age where older age was associated with worsened severity and outcome.

Lateralization of mesial temporal lobe epilepsy with chronic ambulatory electrocorticography

OBJECTIVE

Patients with suspected mesial temporal lobe (MTL) epilepsy typically undergo inpatient video-electroencephalography (EEG) monitoring with scalp and/or intracranial electrodes for 1 to 2 weeks to localize and lateralize the seizure focus or foci. Chronic ambulatory electrocorticography (ECoG) in patients with MTL epilepsy may provide additional information about seizure lateralization. This analysis describes data obtained from chronic ambulatory ECoG in patients with suspected bilateral MTL epilepsy in order to assess the time required to determine the seizure lateralization and whether this information could influence treatment decisions.

METHODS

Ambulatory ECoG was reviewed in patients with suspected bilateral MTL epilepsy who were among a larger cohort with intractable epilepsy participating in a randomized controlled trial of responsive neurostimulation. Subjects were implanted with bilateral MTL leads and a cranially implanted neurostimulator programmed to detect abnormal interictal and ictal ECoG activity. ECoG data stored by the neurostimulator were reviewed to determine the lateralization of electrographic seizures and the interval of time until independent bilateral MTL electrographic seizures were recorded.

RESULTS

Eighty-two subjects were implanted with bilateral MTL leads and followed for 4.7 years on average (median 4.9 years). Independent bilateral MTL electrographic seizures were recorded in 84%. The average time to record bilateral electrographic seizures in the ambulatory setting was 41.6 days (median 13 days, range 0-376 days). Sixteen percent had only unilateral electrographic seizures after an average of 4.6 years of recording.

SIGNIFICANCE

About one third of the subjects implanted with bilateral MTL electrodes required >1 month of chronic ambulatory ECoG before the first contralateral MTL electrographic seizure was recorded. Some patients with suspected bilateral MTL seizures had only unilateral electrographic seizures. Chronic ambulatory ECoG in patients with suspected bilateral MTL seizures provides data in a naturalistic setting, may complement data from inpatient video-EEG monitoring, and can contribute to treatment decisions.

Migration to the ICD-10 coding system: A primer for spine surgeons (Part 1)

Background:

On 1 October 2015, a new federally mandated system goes into effect requiring the replacement of the International Classification of Disease-version 9-Clinical Modification (ICD-9-CM) with ICD-10-CM. These codes are required to be used for reimbursement and to substantiate medical necessity. ICD-10 is composite with as many as 141,000 codes, an increase of 712% when compared to ICD-9.

Methods:

Execution of the ICD-10 system will require significant changes in the clinical administrative and hospital-based practices. Through the transition, diminished productivity and practice revenue can be anticipated, the impacts of which the spine surgeon can minimizeby appropriate education and planning.

Results:

The advantages of the new system include increased clarity and more accurate definitions reflecting patient condition, information relevant to ambulatory and managed care encounters, expanded injury codes, laterality, specificity, precise data for safety and compliance reporting, data mining for research, and finally, enabling pay-for-performance programs. The disadvantages include the cost per physician, training administrative staff, revenue loss during the learning curve, confusion, the need to upgrade hardware along with software, and overall expense to the healthcare system.

Conclusions:

With the deadline rapidly approaching, gaps in implementation result in delayed billing, delayed or diminished reimbursements, and absence of quality and outcomes data. It is thereby essential for spine surgeons to understand their role in transitioning to this new environment. Part I of this article discusses the background, coding changes, and costs as well as reviews the salient features of ICD-10 in spine surgery

Implementation and impact of ICD-10 (Part II)

BACKGROUND

The transition from the International Classification of Disease-9(th) clinical modification to the new ICD-10 was all set to occur on 1 October 2015. The American Medical Association has previously been successful in delaying the transition by over 10 years and has been able to further postpone its introduction to 2015. The new system will overcome many of the limitations present in the older version, thus paving the way to more accurate capture of clinical information.

METHODS

The benefits of the new ICD-10 system include improved quality of care, potential cost savings, reduction of unpaid claims, and improved tracking of healthcare data. The areas where challenges will be evident include planning and implementation, the cost to transition, a shortage of qualified coders, training and education of the healthcare workforce, and a loss of productivity when this occurs. The impacts include substantial costs to the healthcare system, but the projected long-term savings and benefits will be significant. Improved fraud detection, accurate data entry, ability to analyze cost benefits with procedures, and enhanced quality outcome measures are the most significant beneficial factors with this change.

RESULTS

The present Current Procedural Terminology and Healthcare Common Procedure Coding System code sets will be used for reporting ambulatory procedures in the same manner as they have been. ICD-10-PCS will replace ICD-9 procedure codes for inpatient hospital services. The ICD-10-CM will replace the clinical code sets. Our article will focus on the challenges to execution of an ICD change and strategies to minimize risk while transitioning to the new system.

CONCLUSION

With the implementation deadline gradually approaching, spine surgery practices that include multidisciplinary health specialists have to anticipate and prepare for the ICD change in order to mitigate risk. Education and communication is the key to this process in spine practices.

Two-year seizure reduction in adults with medically intractable partial onset epilepsy treated with responsive neurostimulation: final results of the RNS System Pivotal trial

OBJECTIVE

To demonstrate the safety and effectiveness of responsive stimulation at the seizure focus as an adjunctive therapy to reduce the frequency of seizures in adults with medically intractable partial onset seizures arising from one or two seizure foci.

METHODS

Randomized multicenter double-blinded controlled trial of responsive focal cortical stimulation (RNS System). Subjects with medically intractable partial onset seizures from one or two foci were implanted, and 1 month postimplant were randomized 1:1 to active or sham stimulation. After the fifth postimplant month, all subjects received responsive stimulation in an open label period (OLP) to complete 2 years of postimplant follow-up.

RESULTS

All 191 subjects were randomized. The percent change in seizures at the end of the blinded period was -37.9% in the active and -17.3% in the sham stimulation group (p = 0.012, Generalized Estimating Equations). The median percent reduction in seizures in the OLP was 44% at 1 year and 53% at 2 years, which represents a progressive and significant improvement with time (p < 0.0001). The serious adverse event rate was not different between subjects receiving active and sham stimulation. Adverse events were consistent with the known risks of an implanted medical device, seizures, and of other epilepsy treatments. There were no adverse effects on neuropsychological function or mood.

SIGNIFICANCE

Responsive stimulation to the seizure focus reduced the frequency of partial-onset seizures acutely, showed improving seizure reduction over time, was well tolerated, and was acceptably safe. The RNS System provides an additional treatment option for patients with medically intractable partial-onset seizures.

Overdrainage shunt complications in idiopathic normal-pressure hydrocephalus and lumbar puncture opening pressure

OBJECT

Management of idiopathic normal-pressure hydrocephalus (iNPH) is hard because the diagnosis is difficult and shunt surgery has high complication rates. An important complication is overdrainage, which often can be treated with adjustable-shunt valve manipulations but also may result in the need for subdural hematoma evacuation. The authors evaluated shunt surgery overdrainage complications in iNPH and their relationship to lumbar puncture opening pressure (LPOP).

METHODS

The authors reviewed the charts of 164 consecutive patients with iNPH who underwent shunt surgery at their institution from 2005 to 2011. They noted age, sex, presenting symptoms, symptom duration, hypertension, body mass index (BMI), imaging findings of atrophy, white matter changes, entrapped sulci, LPOP, valve opening pressure (VOP) setting, number of valve adjustments, serious overdrainage (subdural hematoma requiring surgery), radiological overdrainage (subdural hematomas or hygroma seen on postoperative imaging), clinical overdrainage (sustained or postural headache), other complications, and improvements in gait, urine control, and memory.

RESULTS

Eight patients (5%) developed subdural hematomas requiring surgery. All had an LPOP of greater than 160 mm H2O and an LPOP-VOP of greater than 40 mm H2O. Radiological overdrainage was more common in those with an LPOP of greater than 160 mm H2O than in those with an LPOP of less than 160 mm H2O (38% vs. 21%, respectively; p = 0.024). The BMI was also significantly higher in those with an LPOP of greater than 160 mm H2O (median 30.2 vs. 27.0, respectively; p = 0.005).

CONCLUSIONS

Serious overdrainage that caused subdural hematomas and also required surgery after shunting was related to LPOP and LPOP-VOP, which in turn were related to BMI. If this can be replicated, individuals with a high LPOP should have their VOP set close to the LPOP, or even higher. In doing this, perhaps overdrainage complications can be reduced.

Signal characteristics of intraventricular electrodes recordings in human epilepsy: a case report

The case of a patient with intractable temporal lobe seizures and inadvertent unilateral intraventricular depth electrode placement is presented. The resting electroencephalograph (EEG) showed marked amplitude differences between the intraventricular electrode on the left and the parenchymal electrode on the right. All recorded seizures originated on the left side and in spite of its intraventricular location, frequency power spectra during the early ictal phase showed a marked increase in power for all frequency bands in the left depth electrode, exceeding that on the right. Analysis with Brain Electrical Source Analysis (BESA) software demonstrated marked ictal baseline shifts which were initially limited to the left side but changed to the right during clinical secondary generalization. In the immediate postictal state, all, except for infraslow, frequencies were markedly reduced in power. We conclude that intraventricular depth electrode contacts placed adjacent to the hippocampal structure can record interictal and ictal activity for all frequency bands, albeit at reduced amplitudes. Furthermore, infraslow activity can provide supplementary information about the epileptogenic zone.

Anterior cervical osteophyte dysphagia: manofluorographic and functional outcomes after surgery

BACKGROUND

Our aim was to investigate the clinical and manofluorographic findings of patients with anterior cervical osteophyte (ACO) dysphagia before and after surgery.

METHODS

Chart review including manofluorography (MFG) data of patients undergoing ACO removal was undertaken.

RESULTS

Thirteen patients underwent transcervical ACO removal over a 10-year period. A postoperative hematoma was the only surgical complication. Overall, there was a significant postoperative decrease in Functional Outcome Swallowing Scale (FOSS). MFG data showed an elevated preoperative intrabolus pressure gradient across the osteophyte (IB-Gra), 39.78 mm Hg, and IB-Gra significantly decreased to 19 mm Hg 6 months after surgery.

CONCLUSION

Functional (FOSS) and objective MFG (IB-Gra) improvements occurred in patients who had ACO dysphagia and underwent surgery. These findings support high IB-Gra as a reliable objective indicator for surgical intervention for ACO dysphagia and IB-Gra as an appropriate parameter for follow-up after ACO removal. In selected patients, ACO removal by anterolateral-transcervical approach is a safe and highly effective treatment.

Iatrogenic intradural spinal arachnoid cyst as a complication of lumbar spine surgery

Iatrogenic spinal arachnoid cysts are rare, but have been described as a complication of spinal injection and lumbar puncture procedures. The authors describe 2 cases of iatrogenic spinal arachnoid cyst formation that occurred after incidental durotomy during lumbar spine surgery. In both cases, postoperative MR imaging revealed compression of the cauda equina by an intradural arachnoid cyst. Intradural exploration and fenestration of the arachnoid cyst was accomplished in each case. This entity should be considered in the differential diagnosis of a patient experiencing symptoms of neurological compression after a lumbar surgery complicated by incidental durotomy.

Trigeminal neuralgia in a patient with spontaneous intracranial hypotension

Spontaneous intracranial hypotension and trigeminal neuralgia are examples of pain syndromes arising from shifting anatomical relationships in the posterior fossa. We report both conditions occurring in the same patient and resolving following surgical closure of a cervical nerve root sleeve dural defect. This case further elucidates the pathophysiologic basis of both forms of head pain.

Correlation of outcome to neurosurgical lesions: confirmation of a new method using data after microelectrode-guided pallidotomy

The purpose of this study was the development of a new method to correlate functional surgery with outcome measures. Lesions following microelectrode guided globus pallidus internus (GPi) pallidotomy for Parkinson's disease are presented to demonstrate this new method in regard to clinical outcome. A clinical series of 26 patients with extensive neurological and neuropsychological data were studied. Three-month postoperative MRI lesion borders at the AC-PC plane were scaled to a standard size, and the lesions were stored in a virtual array with a cell size of one voxel. The average outcome measure for each voxel is presented graphically. Unified Parkinson's disease rating scale (UPDRS) motor scores improved more with posterolateral and centrally located GPi lesions than with anteromedial lesions. A correlation of lesion location to outcome was also visible for subscales of the UPDRS. The distributions were similar for the left and right sides, as well as for ipsi- and contralateral measurements. In general, verbal fluency decreased after lesioning the dominant hemisphere, and posterolateral lesions caused less impairment. This method enables associative analyses between brain area and outcome down to the size of a few voxels. This may be particularly helpful for planning and validating neurosurgical targets for various disorders.

Responsive cortical stimulation for the treatment of epilepsy

Epilepsy is a common chronic neurological disorder affecting approximately 1-2% of the population. Despite the available treatment options (pharmacotherapy, surgery, and vagus nerve stimulation), a large percentage of patients continue to have seizures. With the success of deep brain stimulation for treatment of movement disorders, brain stimulation has received renewed attention as a potential treatment option for epilepsy. Responsive stimulation aims to suppress epileptiform activity by delivering stimulation directly in response to electrographic activity. Animal and human data support the concept that responsive stimulation can abort epileptiform activity, and this modality may be a safe and effective treatment option for epilepsy. Responsive stimulation has the advantage of specificity. In contrast to the typically systemic administration of pharmacotherapy, with the concomitant possibility of side effects, electrical stimulation can be targeted to the specific brain regions involved in the seizure. In addition, responsive stimulation provides temporal specificity. Treatment is provided as needed, potentially reducing the likelihood of functional disruption or habituation due to continuous treatment. Here we review current animal and human research in responsive brain stimulation for epilepsy and then discuss the NeuroPace RNS System, an investigational implantable responsive neurostimulator system that is being evaluated in a multicenter, randomized, double-blinded trial to assess the safety and efficacy of responsive stimulation for the treatment of medically refractory epilepsy.

Unilateral deep brain stimulation of the subthalamic nucleus for Parkinson disease

OBJECT

The object of this study was to assess the results of unilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) for management of advanced Parkinson disease (PD).

METHODS

A clinical series of 24 patients (mean age 71 years, range 56-80 years) with medically intractable PD, who were undergoing unilateral magnetic resonance imaging-targeted, electrophysiologically guided STN DBS, completed a battery of qualitative and quantitative outcome measures preoperatively (baseline) and postoperatively, using a modified Core Assessment Program for Intracerebral Transplantations protocol. The mean follow-up period was 9 months. Statistically significant improvement was observed in the Unified Parkinson's Disease Rating Scale (UPDRS) Part II score (18%), the total UPDRS PART III score (31%), the contralateral UPDRS Part III score (63%), and scores for axial motor features (19%), contralateral tremor (88%), rigidity (60%), bradykinesia (54%), and dyskinesia (69%), as well as the Parkinson's Disease Quality of Life questionnaire score (15%) in the on-stimulation state compared with baseline. Ipsilateral symptoms improved by approximately 15% or less. Performance on the Purdue pegboard test improved in the contralateral hand in the on-stimulation state compared with the off-stimulation state (38%, p < 0.05). The daily levodopa-equivalent dose was reduced by 21% (p = 0.018). Neuropsychological tests revealed an improvement in mental flexibility and a trend toward reduced letter fluency. There were no permanent surgical complications. Of the 16 participants with symmetrical disease, five required implantation of the DBS unit on the second side.

CONCLUSIONS

Unilateral STN DBS is an effective and safe treatment for selected patients with advanced PD. Unilateral STN DBS provides improvement of contralateral motor symptoms of PD as well as quality of life, reduces requirements for medication, and possibly enhances mental flexibility. This method of surgical treatment may be associated with a reduced risk and may provide an alternative to bilateral STN DBS for PD, especially in older patients or patients with asymmetry of parkinsonism.

Cervical Sympathetic Neuralgia Arising From a Schwannoma

We describe an unusual case of neuropathic pain of the left face and shoulder accompanied by ipsilateral hyperhidrosis caused by a schwannoma of the cervical sympathetic chain. Additional signs of associated sympathetic hyperactivity included left-sided lacrimation, conjunctival injection, and nasal congestion. Autonomic testing demonstrated signs of increased vasomotor and sudomotor activity in the left palm. The pain was refractory to analgesic and antimigraine medications but resolved following surgical resection of the T2 schwannoma.