Magnetoencephalography for Epilepsy Presurgical Evaluation.

PURPOSE OF THE REVIEW: Magnetoencephalography (MEG) is a functional neuroimaging technique that records neurophysiology data with millisecond temporal resolution and localizes it with subcentimeter accuracy. Its capability to provide high resolution in both of these domains makes it a powerful tool both in basic neuroscience as well as clinical applications. In neurology, it has proven useful in its ability to record and localize epileptiform activity. Epilepsy workup typically begins with scalp electroencephalography (EEG), but in many situations, EEG-based localization of the epileptogenic zone is inadequate. The complementary sensitivity of MEG can be crucial in such cases, and MEG has been adopted at many centers as an important resource in building a surgical hypothesis. In this paper, we review recent work evaluating the extent of MEG influence of presurgical evaluations, novel analyses of MEG data employed in surgical workup, and new MEG instrumentation that will likely affect the field of clinical MEG. RECENT FINDINGS: MEG consistently contributes to presurgical evaluation and these contributions often change the plan for epilepsy surgery. Extensive work has been done to develop new analytic methods for localizing the source of epileptiform activity with MEG. Systems using optically pumped magnetometry (OPM) have been successfully deployed to record and localize epileptiform activity. MEG remains an important noninvasive tool for epilepsy presurgical evaluation. Continued improvements in analytic methodology will likely increase the diagnostic yield of the test. Novel instrumentation with OPM may contribute to this as well, and may increase accessibility of MEG by decreasing cost.

Gluteus Repair Yields Satisfactory Clinically Significant Outcome Achievement by 1 Year in Mostly Partial-Thickness Tears With Preoperative Hip Abduction Weakness Associated With Delayed Achievement.

PURPOSE: To define the time to achievement of clinically significant outcomes (CSOs) after primary gluteus medius and/or minimus (GM) repair and to identify factors associated with delayed CSO achievement. METHODS: Patients who underwent primary GM repair between January 2012 and June 2021 with complete preoperative, 6-month, 1-year, and 2-year Hip Outcome Score-Activities of Daily Living (HOS-ADL) were retrospectively identified. Cohort-specific minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) were calculated. The time to achievement of MCID and PASS was analyzed using Kaplan-Meier survival analysis. Median time to MCID and PASS achievement was recorded. Multivariate stepwise Cox regressions were used to identify factors associated with delayed CSO achievement. RESULTS: Fifty GM repairs were identified (age 59.4 ± 9.7 years, body mass index 27.9 ± 6.2, 94% female). Tears were grade 1 in 39 cases, grade 2 in 7 cases, and grade 3 in 4 cases. Endoscopic repair was performed in 35 cases, and open repair was performed in 15 cases. Labral debridement and repair were each performed in 15 cases. Median time to CSO achievement was 5.7 months for MCID and 11.0 months for PASS. The 2-year cumulative probability of MCID and PASS achievement was 92.7% and 66.7%, respectively. Preoperative hip abduction weakness on physical examination was associated with delayed achievement of MCID (hazard ratio 2.27, confidence interval 1.067-7.41, P = .039) and PASS (hazard ratio 3.89, confidence interval 1.341-11.283, P = .012). CONCLUSIONS: This study demonstrated that in patients undergoing repair of primarily grade 1 GM tears, most achieved MCID by 6 months, and more than one half achieved PASS by 12 months. Preoperative hip abduction weakness on physical examination was associated with delayed CSO achievement. LEVEL OF EVIDENCE: Level IV, retrospective case series.

3-dimensionally printed patient-specific glenoid drill guides vs. standard nonspecific instrumentation: a randomized controlled trial comparing the accuracy of glenoid component placement in anatomic total shoulder arthroplasty.

BACKGROUND: Traditional, commercially sourced patient-specific instrumentation (PSI) systems for shoulder arthroplasty improve glenoid component placement but can involve considerable cost and outsourcing delays. The purpose of this randomized controlled trial was to compare the accuracy of glenoid component positioning in anatomic total shoulder arthroplasty (aTSA) using an in-house, point-of-care, 3-dimensionally (3D) printed patient-specific glenoid drill guide vs. standard nonspecific instrumentation. METHODS: This single-center randomized controlled trial included 36 adult patients undergoing primary aTSA. Patients were blinded and randomized 1:1 to either the PSI or the standard aTSA guide groups. The primary endpoint was the accuracy of glenoid component placement (version and inclination), which was determined using a metal-suppression computed tomography scan taken between 6 weeks and 1 year postoperatively. Deviation from the preoperative 3D templating plan was calculated for each patient. Blinded postoperative computed tomography measurements were performed by a fellowship-trained shoulder surgeon and a musculoskeletal radiologist. RESULTS: Nineteen patients were randomized to the patient-specific glenoid drill guide group, and 17 patients were allocated to the standard instrumentation control group. There were no significant differences between the 2 groups for native version (P = .527) or inclination (P = .415). The version correction was similar between the 2 groups (P = .551), and the PSI group was significantly more accurate when correcting version than the control group (P = .042). The PSI group required a significantly greater inclination correction than the control group (P = .002); however, the 2 groups still had similar accuracy when correcting inclination (P = .851). For the PSI group, there was no correlation between the accuracy of component placement and native version, native inclination, or the Walch classification of glenoid wear (P > .05). For the control group, accuracy when correcting version was inversely correlated with native version (P = .033), but accuracy was not correlated with native inclination or the Walch classification of glenoid wear (P > .05). The intraclass correlation coefficient was 0.703 and 0.848 when measuring version and inclination accuracy, respectively. CONCLUSION: When compared with standard instrumentation, the use of in-house, 3D printed, patient-specific glenoid drill guides during aTSA led to more accurate glenoid component version correction and similarly accurate inclination correction. Additional research should examine the influence of proper component position and use of PSI on clinical outcomes.

From theory to practical fundamentals of electroencephalographic source imaging in localizing the epileptogenic zone.

With continued advancement in computational technologies, the analysis of electroencephalography (EEG) has shifted from pure visual analysis to a noninvasive computational technique called EEG source imaging (ESI), which involves mathematical modeling of dipolar and distributed sources of a given scalp EEG pattern. ESI is a noninvasive phase I test for presurgical localization of the seizure onset zone in focal epilepsy. It is a relatively inexpensive modality, as it leverages scalp EEG and magnetic resonance imaging (MRI) data already collected typically during presurgical evaluation. With an adequate number of electrodes and combined with patient-specific MRI-based head models, ESI has proven to be a valuable and accurate clinical diagnostic tool for localizing the epileptogenic zone. Despite its advantages, however, ESI is routinely used at only a minority of epilepsy centers. This paper reviews the current evidence and practical fundamentals for using ESI of interictal and ictal epileptic activity during the presurgical evaluation of drug-resistant patients. We identify common errors in processing and interpreting ESI studies, describe the differences in approach needed for localizing interictal and ictal EEG discharges through practical examples, and describe best practices for optimizing the diagnostic information available from these studies.

Effective Use of Sirolimus and Zoledronic Acid for Multiosteotic Pseudomyogenic Hemangioendothelioma of the Bone in a Child: Case Report and Review of Literature.

Pseudomyogenic hemangioendothelioma (PMH) is a rare neoplasm with vascular and sarcomatous elements, unpredictable course, and uncommon metastatic or fatal potential. Although systemic chemotherapy has been reported with variable success, generally accepted treatment is aggressive surgery with wide margins. Evidence-based treatment options are lacking, and lack of clear prognostic features poses a risk of undertreatment or overtreatment with associated morbidity and mortality. We report the use of initial systemic therapy with oral sirolimus (SIR) and IV zoledronic acid (ZA) to induce a sustained clinical response and avoidance of amputation in a 6-year-old boy. At 37 months after diagnosis, our patient remains in sustained clinical remission as documented by x-ray, MRI, and PET-CT with return of normal mobility/activity and resolution of swelling and pain. Literature review identified 20 cases of pediatric and young adult patients with PMH, of which 7 received some form of systemic therapy. To the best of our knowledge, our patient represents the youngest reported case of PMH and the first successful and limb-sparing utilization of systemic chemotherapy as primary treatment for PMH.

Diadema antillarum on St. Croix, USVI: Current Status and Interactions with Herbivorous Fishes.

The 1983-84 mass mortality of the long-spined sea urchin, Diadema antillarum, intensified the loss of herbivory that was a major factor in the degradation of coral reefs in the wider Caribbean. As determined from recent surveys, densities of D. antillarum populations at back reef locations on St. Croix, US Virgin Islands, are higher than densities immediately following the die-off - but still about an order of magnitude below pre-die-off densities and patchy in both time and space. Comparisons to similar surveys during the past twelve years and to earlier historical records indicate that recovery on St. Croix continues at the very slow rate that typified the first decade after the mass mortality. Populations of herbivorous fishes on St. Croix surged following the D. antillarum die-off but have experienced heavy fishing pressure ever since then. Reciprocal densities of D. antillarum versus roaming grazers (parrotfishes and surgeonfishes) on survey transects and stationary point counts indicate that negative interaction between these two groups is present despite the reductions to their populations during the last 35 years.

EEG Source Imaging in Presurgical Evaluations.

SUMMARY: Presurgical evaluations to plan intracranial EEG implantations or surgical therapies at most epilepsy centers in the United States currently depend on the visual inspection of EEG traces. Such analysis is inadequate and does not exploit all the localizing information contained in scalp EEG. Various types of EEG source modeling or imaging can provide sublobar localization of spike and seizure sources in the brain, and the software to do this with typical long-term monitoring EEG data are available to all epilepsy centers. This article reviews the fundamentals of EEG voltage fields that are used in EEG source imaging, the strengths and weakness of dipole and current density source models, the clinical situations where EEG source imaging is most useful, and the particular strengths of EEG source imaging for various cortical areas where spike/seizure sources are likely.

Association Between Proximal Hamstring Tear Characteristics and Achievement of Clinically Significant Outcomes After Endoscopic and Open Repair at Minimum 2-Year Follow-up.

BACKGROUND: The effect of preoperative tear characteristics and the relative efficacy of open versus endoscopic surgical techniques have not been elucidated for the surgical treatment of proximal hamstring tendon injuries. PURPOSE: (1) To report on achievement rates of clinically significant outcomes at a minimum 2-year follow-up for multiple patient-reported outcomes (PROs) after surgical treatment of proximal hamstring injuries, stratified according to severity of proximal hamstring injury, and (2) to compare clinical outcomes associated with endoscopic versus open surgical repair for a subset of similarly classified tears. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A single-surgeon clinical registry was queried for patients who underwent surgical repair for proximal hamstring ruptures between January 2012 and March 2021. Injuries were classified by magnetic resonance imaging as follows: grade 1, incomplete tear with the involvement of 1 or 2 tendons; grade 2, complete tear with the involvement of 3 tendons and ≤2-cm retraction; and grade 3, complete tear with the involvement of 3 tendons and >2-cm retraction. The Patient Acceptable Symptom State (PASS) for multiple PROs was calculated and compared among injury grades and between surgical techniques. RESULTS: Among 75 patients with a mean follow-up of 30.5 ± 5.1 months, 20 had grade 1 tears, 24 had grade 2 tears, and 31 had grade 3 tears. Favorable 2-year postoperative PROs were demonstrated by each grade for all measured PROs. Patients with grade 3 tears were noted to have significantly lower rates of 2-year PASS achievement for the Hip Outcome Score-Activities of Daily Living (HOS-ADL) and Hip Outcome Score-Sports Specific (HOS-SS) scales (P≤ .032). Among grade 2 tears, patients treated endoscopically demonstrated significantly greater HOS-SS (endoscopic, 91.7%; open, 58.3%; P = .045) and Patient-Reported Outcomes Measurement Information System for Physical Function (endoscopic, 80.0%; open, 50.0%; P = .033) PASS achievement rates compared with those treated with the open technique. Complication rates were highest in patients with grade 3 tears (45.2%, P = .043). CONCLUSION: Surgical repair of proximal hamstring tendon tears with varying extents of tendon retraction resulted in high rates of achieving PASS at the 2-year follow-up. Among complete tears with <2 cm of retraction, endoscopic repairs exhibited equal or higher rates of achieving PASS compared with open repairs across multiple PROs at 2 years postoperatively. However, patients with complete tears and retraction >2 cm achieved lower rates of PASS on the HOS-ADL and HOS-SS scales and had a higher rate of complications.

Tonic phase of a generalized convulsive seizure is an independent predictor of postictal generalized EEG suppression.

PURPOSE: To determine the incidence, duration, risk factors for, and clinical correlates of postictal generalized electroencephalography (EEG) suppression (PGES), and to further delineate the significance of PGES in the pathogenesis of sudden unexpected death in epilepsy (SUDEP). METHODS: We retrospectively reviewed the video-EEG studies of 109 consecutive patients with 151 generalized convulsive seizures (GCS) during video-EEG monitoring. We determined the incidence, duration, and clinical correlates of PGES. We also investigated whether factors such as age, sex, seizure type, total seizure duration, and duration of tonic and clonic phases influenced PGES. KEY FINDINGS: PGES was observed in 64 (58.7%) of 109 patients and in 98 (64.9%) of 151 GCS. Average duration of PGES was 42.4 ± 19.1 s. Statistical analysis showed that patients with PGES had no difference in age, gender, total seizure duration, total convulsive duration, clonic phase, seizure type, and seizure termination, as compared to those without PGES. However, tonic phase was significantly prolonged in patients with PGES than in those without PGES (p = 0.00086). A 1 s increase in tonic phase duration was associated with a 0.06 increase in log odds of PGES (odds ratio = 1.1, p = 0.00055). Clinically, 95.3% patients were unresponsive or immobile during PGES, whereas only 26.7% patients without PGES were unresponsive or immobile immediately after seizure termination. SIGNIFICANCE: PGES is a common EEG pattern of GCS. Tonic phase of GCS is an independent predictor of PGES, which is well correlated with postictal unresponsiveness or immobile, and may play a significant role in the mechanism of SUDEP.

Three-Grade Magnetic Resonance Imaging-Based Gluteus Medius and/or Minimus Tear Classification System Provides Excellent Inter-Rater Reliability.

Purpose: To develop a magnetic resonance imaging (MRI)-based classification system integrating tear characteristics including tear thickness (partial vs full) and tear retraction (less than or greater than 2 cm) for gluteus medius and/or minimus tears and to determine the inter-rater reliability of this MRI-based classification for gluteus medius and/or minimus tears. Methods: Patients who underwent primary endoscopic or open repair of gluteus medius and/or minimus tears between 2012 and 2022 were identified to be included in the review of 1.5-T MRI scans. One hundred MRI scans were randomized for review by 2 orthopaedic surgeons and evaluated for tear thickness (partial vs full), extent of retraction, and degree of fatty infiltration according to an applied Goutallier-Fuchs (G-F) classification. Tears were also graded according to the 3-grade MRI-based classification system as follows: grade 1, partial-thickness tears; grade 2, full-thickness tears with less than 2 cm of retraction; grade 3, full thickness with 2 cm or more retraction. Inter-rater reliability was calculated by absolute and relative agreement using Cohen's kappa (κ). Significance was defined by P value <.05. Results: In total, 221 patients were identified, and after application of exclusion criteria and randomization, 100 scans were evaluated. The 3-grade classification system demonstrated high absolute agreement (88%) comparable to the absolute agreement of the G-F classification (67%). The 3-grade classification system demonstrated substantial inter-rater reliability (κ = 0.753), whereas the G-F classification demonstrated moderate inter-rater reliability (κ = 0.489). Conclusions: The proposed 3-grade MRI-based classification system for gluteus medius and/or minimus tears demonstrated substantial inter-rater reliability, comparable with that of the applied G-F classification. Clinical Relevance: It is important to understand how gluteus medius and/or minimus tear characteristics impact postoperative outcomes. The 3-grade MRI-based classification incorporates tear thickness and amount of retraction that can complement previous classification systems to give the provider and patient more information when considering treatment options.

Clinical Outcomes After Open and Endoscopic Repair of Proximal Hamstring Tendon Tears at a Minimum Follow-up of 5 Years.

Background: Current evidence supports favorable short-term clinical outcomes with few complications after surgical management of proximal hamstring injuries; however, the durability of clinical benefits beyond approximately 2 years after surgery is unknown. Purpose: To evaluate patient-reported clinical outcomes and complication rates associated with open and endoscopic repair of proximal hamstring tears at minimum 5-year follow-up. Study Design: Case series; Level of evidence, 4. Methods: A single-surgeon registry of patients was queried between October 1, 2014, and December 31, 2017, to identify patients who underwent open or endoscopic repair of a proximal hamstring tear. Patients who reported minimum 5-year follow-up data were included. Multiple patient-reported outcome measures, including the Hip Outcome Score Activities of Daily Living (HOS-ADL) and Sports-Specific (HOS-SS) subscales, 12-Item International Hip Outcome Tool (iHOT-12), and Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) and Pain domains, along with surgical complications, were analyzed. Results: Among 35 eligible patients (65.7% female; mean age, 52.3 ± 8.4 years), 24 had full-thickness tears and 11 had partial-thickness tears. There were 23 open repairs and 12 endoscopic repairs. Mean duration from symptom onset to surgical intervention was 37.9 weeks (range, 1.3-306.9 weeks). At a mean follow-up of 69.0 months (range, 60.0-95.0 months), mean postoperative outcome scores were as follows: HOS-ADL, 86.8 ± 12.7; HOS-SS, 83.1 ± 19.5; iHOT-12, 86.3 ± 14.9; PROMIS-PF, 50.0 ± 11.8; and PROMIS-Pain, 50.2 ± 7.9. Regarding complications, 28.6% of patients had a complication including persistent peri-incisional numbness (11.4%), wound infection (11.4%), postoperative neuropathy (8.6%), and revision surgery (2.9%). Conclusion: Both open and endoscopic surgical techniques for repair of proximal hamstring injuries produced favorable patient-reported clinical outcomes at a minimum 5-year follow-up.

Interictal regional delta slowing is an EEG marker of epileptic network in temporal lobe epilepsy.

PURPOSE: Several studies have suggested that interictal regional delta slowing (IRDS) carries a lateralizing and localizing value similar to interictal spikes and is associated with favorable surgical outcomes in patients with temporal lobe epilepsy (TLE). However, whether IRDS reflects structural dysfunction or underlying epileptic activity remains controversial. The objective of this study is to determine the cortical electroencephalography (EEG) correlates of scalp-recorded IRDS, in so doing, to further understand its clinical and biologic significances. METHODS: We examined the cortical EEG substrates of IRDS with electrocorticography (ECoG-IRDS) and delineated the spatiotemporal relationship between ECoG-IRDS and both interictal and ictal discharges by recording simultaneously scalp and intracranial EEG in 18 presurgical candidates with TLE. KEY FINDINGS: Our results demonstrated that ECoG-IRDS is typically a mixture of delta/theta slowing and spike-wave potentials. ECoG-IRDS was predominantly recorded from basal and anterolateral temporal cortex, occasionally in mesial, posterior temporal, and extratemporal regions. Abundant IRDS was most commonly observed in patients with neocortical temporal lobe epilepsy (NTLE), whereas infrequent to moderate IRDS was usually observed in patients with mesial temporal lobe epilepsy (MTLE). The anatomic distribution of ECoG-IRDS was highly correlated with the irritative and seizure-onset zones in 10 patients with NTLE. However, it was poorly correlated with the irritative and seizure-onset zones in the 8 patients with MTLE. SIGNIFICANCE: These findings demonstrate that IRDS is an EEG marker of epileptic network in patients with TLE. Although IRDS and interictal/ictal discharges likely arise from the same neocortical generator in patients with NTLE, IRDS in patients with MTLE may reflect a network disease that involves temporal neocortex.

Practical Fundamentals of Clinical MEG Interpretation in Epilepsy.

Magnetoencephalography (MEG) is a neurophysiologic test that offers a functional localization of epileptic sources in patients considered for epilepsy surgery. The understanding of clinical MEG concepts, and the interpretation of these clinical studies, are very involving processes that demand both clinical and procedural expertise. One of the major obstacles in acquiring necessary proficiency is the scarcity of fundamental clinical literature. To fill this knowledge gap, this review aims to explain the basic practical concepts of clinical MEG relevant to epilepsy with an emphasis on single equivalent dipole (sECD), which is one the most clinically validated and ubiquitously used source localization method, and illustrate and explain the regional topology and source dynamics relevant for clinical interpretation of MEG-EEG.

Case Study: Mapping Evoked Fields in Primary Motor and Sensory Areas via Magnetoencephalography in Tetraplegia.

Devices interfacing with the brain through implantation in cortical or subcortical structures have great potential for restoration and rehabilitation in patients with sensory or motor dysfunction. Typical implantation surgeries are planned based on maps of brain activity generated from intact function. However, mapping brain activity for planning implantation surgeries is challenging in the target population due to abnormal residual function and, increasingly often, existing MRI-incompatible implanted hardware. Here, we present methods and results for mapping impaired somatosensory and motor function in an individual with paralysis and an existing brain-computer interface (BCI) device. Magnetoencephalography (MEG) was used to directly map the neural activity evoked during transcutaneous electrical stimulation and attempted movement of the impaired hand. Evoked fields were found to align with the expected anatomy and somatotopic organization. This approach may be valuable for guiding implants in other applications, such as cortical stimulation for pain and to improve implant targeting to help reduce the craniotomy size.

SUDEP, suspected positional airway obstruction, and hypoventilation in postictal coma.

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of mortality in patients with chronic uncontrolled epilepsy. Despite intense interest in SUDEP from the medical and scientific communities in recent years, its etiologies are still largely unresolved. A 35-year-old woman had SUDEP after having a generalized seizure in the prone position. The cause of her death was likely asphyxia from the convergence of postictal coma and suspected positional airway obstruction and hypoventilation, rather than the commonly suspected periictal cardiac arrhythmia or central apnea. SUDEP may share a similar etiology with sudden infant death syndrome (SIDS) and is likely preventable, at least in a proportion of cases.

Relative Yield of MEG and EEG Spikes in Simultaneous Recordings.

PURPOSE: Most clinical magnetoencephalography (MEG) centers record both MEG and EEG, but model only MEG sources. This may be related to the belief that MEG spikes are more prevalent, MEG is more sensitive, or to proprietary software limitations. Biophysics would contend, however, that EEG, being sensitive to radial and tangential source orientations, would provide complementary data for analysis. METHODS: We recorded 306 channels of MEG and 25 channels of EEG simultaneously in 297 consecutive patients over 3 years. We inspected the MEG and EEG recordings separately, identified spikes in both, determined whether their voltage and/or magnetometer magnetic fields were dipolar and thus model-worthy, and segregated them into types based on similar and distinct field topography. We placed for each patient their spike types into categories, including those with both a recognizable MEG and EEG signal and those with only an MEG and only an EEG signal. RESULTS: Eighty-three percent of patients had spikes recorded, and these patients had an average of 2.7 spike types each. Fifty-six percent of spike types were present in both MEG and EEG. However, 36% of spike types were only evident in EEG, whereas 8% were noted in MEG alone. In 49% of patients with spikes, MEG review missed at least one spike type, whereas in 17% of patients, EEG review missed at least one spike type. CONCLUSIONS: To obtain an optimal yield of diagnostic information, EEG should also be subjected to source analysis in any clinical MEG study. EEG and MEG data are indeed complementary.