Discontinuation of Antiseizure Medications in Patients With Brain Tumors

Patients with brain tumors will experience seizures during their disease course. While providers can use antiseizure medications to control these events, patients with brain tumors can experience side effects, ranging from mild to severe, from these medications. Providers in subspecialties such as neurology, neuro-oncology, neurosurgery, radiation oncology, and medical oncology often work with patients with brain tumor to balance seizure control and the adverse toxicity of antiseizure medications. In this study, we sought to explore the problem of brain tumor-related seizures/epilepsy in the context of how and when to consider antiseizure medication discontinuation. Moreover, we thoroughly evaluate the literature on antiseizure medication discontinuation for adult and pediatric patients and highlight recommendations relevant to patients with both brain tumors and seizures.

CNSC-24. THE EPILEPTIC LANDSCAPE OF IDH MUTANT GLIOMAS

Tumor-associated epilepsy (TAE) is a frequent complication of diffusely infiltrative gliomas, and impairs quality-of-life. We previously showed that isocitrate dehydrogenase 1 mutant (IDHmut) gliomas were associated with preoperative seizures, and that D2HG increased synchronized bursts in cultured neurons (PMID: 28404805). But the mechanism whereby this occurs, whether IDHmut inhibitors can block this, and whether seizure risk varies by IDHmut status post-operatively, are unknown. We discovered that exogenous 3 mM D2HG had a 150% greater effect on the firing rate of cultured mouse cortical neurons when nonneoplastic glia cells were present versus when they were absent (P=0.002). Coculture with patient-derived IDHmut glioma cells increased the firing rate of human cortical neuron/astrocyte spheroids by up to 272%, and the IDHmut inhibitor AG881 reduced the excitatory effect of IDHmut glioma cells on spheroids by 79% (P=0.0008). Using a novel in vivo model of TAE, wherein EEG recordings were taken of immunocompetent mice engrafted with isogenic mouse glioma lines (NRAS/ATRX/TP53mut ± IDHmut), we found that IDHmut gliomas produced 7.6-fold more epileptiform spikes than IDHwt gliomas (P=0.004). RNA-Seq analysis of the peritumoral mouse brain tissue showed that this increase in spikes was associated with significantly increased expression of key genes known to be upregulated in epilepsy, including SLC12A5, THSB1, VEGFA, FOSL2, and SYNPO. Treatment with 5 mg/kg AG881 by daily oral gavage reduced those spikes in IDHmut-engrafted mice by 51% within three days (P=0.027), whereas vehicle control had no effect (P=0.33). Among 247 patients with grade 2–4 adult-type diffuse gliomas, multivariable time-to-event analysis showed that post-operative seizure risk was positively associated with pre-operative seizures, subtotal resection, and IDHmut astrocytoma. Together, these data show that (i) the D2HG product of IDHmut gliomas increases neuronal excitation in a glial-dependent manner; (ii) IDHmut also affects post-operative seizure risk; (iii) IDHmut inhibitors may improve TAE control.

The epileptic landscape of IDH mutant gliomas

2064

Background: Tumor-associated epilepsy (TAE) is a frequent complication of diffusely infiltrative gliomas. TAE not only impairs quality-of-life, but it can even be life-threatening. Furthermore, glioma cells have been shown to proliferate and migrate faster when exposed to firing neurons. We previously showed that isocitrate dehydrogenase 1 mutant (IDHmut) gliomas were more likely to cause preoperative seizures than IDH wildtype (IDHwt) gliomas, and that the chemical product of IDHmut, D2HG, increased synchronized network bursts in cultured neurons (PMID: 28404805). But the mechanism whereby this occurs, whether IDHmut inhibitors can block this, and whether seizure risk also varies by IDHmut status postoperatively, are unknown. Methods: Methods are embedded in Results. Results: We discovered that exogenous 3 mM D2HG had a 150% greater effect on the firing rate of cultured mouse cortical neurons when nonneoplastic glia cells were present versus when they were absent ( P=0.002). Although a recently published study suggested that D2HG causes seizures through mTOR activation (PMID: 34994387), we found that D2HG reduced neuronal mTOR activity in neuronal-glial cocultures by 54% ( P=0.0004). Patch clamp analyses showed that, while D2HG does not directly activate glutamate receptors, it does act as a glutamate transport substrate, thus potentially interfering with the ability of glial cells to take up glutamate released into the synaptic cleft. Coculture with patient-derived IDHmut glioma cells increased the firing rate of human cortical neuron/astrocyte spheroids by up to 272%, and an IDHmut inhibitor currently being tested in clinical trials, AG881, reduced the excitatory effect of IDHmut glioma cells on spheroids by 79% ( P=0.0008). Using a novel in vivo model of TAE, wherein EEG recordings were taken of immunocompetent mice engrafted with an isogenic pair of Sleeping Beauty transposase-engineered mouse glioma lines (NRAS/ATRX/TP53mut ± IDHmut), we found that IDHmut gliomas produced 7.6-fold more epileptiform spikes than IDHwt gliomas ( P=0.004). RNA-Seq analysis of the peritumoral mouse brain tissue showed that this increase in spikes was associated with significantly increased expression of key genes known to be upregulated in epilepsy, including SLC12A5, THSB1, VEGFA, FOSL2, and SYNPO. Treatment with 5 mg/kg AG881 by daily oral gavage reduced those spikes in IDHmut-engrafted mice by 51% within three days ( P=0.027), whereas vehicle control had no effect ( P=0.33). Among 247 patients with grade 2–4 adult-type diffuse gliomas, multivariable time-to-event analysis showed that postoperative seizure risk increased with preoperative seizures, subtotal resection, and IDHmut astrocytoma. Conclusions: Together, these data show that (i) the D2HG product of IDHmut gliomas increases neuronal excitation in a glial-dependent manner; (ii) IDHmut also affects postoperative seizure risk; (iii) IDHmut inhibitors may improve TAE control.

QOLP-08. THE LANDSCAPE OF EPILEPSY ASSOCIATED WITH DIFFUSELY INFILTRATIVE GLIOMAS

Seizures are among the most prevalent co-morbidities associated with glioma, and pose a serious threat to patients. Our prior work showed that IDH mutation (IDHmut) was associated with much greater seizure frequency at the time of initial glioma diagnosis. However, less is known about the variables that contribute to seizure risk throughout the course of disease. We therefore collected data from 247 patients with grade 2–4 glioma, and determined seizure risk using Kaplan-Meier survival probabilities and multivariable cox regression analyses. Median follow-up of IDH wildtype (IDHwt) and IDHmut glioma patients was 15 months and 36 months, respectively. Incidence of pre-operative seizures for IDHwt and IDHmut patients was 75/168 (45%) and 60/79 (76%), and incidence of post-operative seizures was 70/168 (42%) and 43/79 (54%), respectively. Patients who had a pre-operative seizure had a shorter time to their first post-operative seizure than patients who never had a pre-operative seizure in both IDHwt (P< 0.0001) and IDHmut (P= 0.039) cohorts. Among IDHmut glioma patients, those with subtotal resections developed post-operative seizures faster (median time to first seizure= 9.9 months) than those with gross-total resections (median not reached) (P= 0.0005), but a similar pattern was not observed in IDHwt glioma patients (P= 0.20). Those with IDHmut astrocytomas more quickly developed post-operative seizures (median= 11.1 months), compared to those with IDHwt astrocytomas (24.9 months) or IDHmut oligodendrogliomas (median not reached) (P= 0.033). Tumor progression closely followed post-operative seizures in patients with IDHwt gliomas when either their first post-operative seizure occurred longer than 6 months following resection, or when their post-operative seizures worsened in quality. These data suggest the best predictors of post-operative seizures are as follows: the presence of pre-operative seizures; extent of surgical resection; IDHmut status. These data will help clinicians better manage glioma patients by identifying those at greatest risk of seizures.

Automated analysis of breathing waveforms using BreathMetrics: a respiratory signal processing toolbox

Nasal inhalation is the basis of olfactory perception and drives neural activity in olfactory and limbic brain regions. Therefore, our ability to investigate the neural underpinnings of olfaction and respiration can only be as good as our ability to characterize features of respiratory behavior. However, recordings of natural breathing are inherently nonstationary, nonsinusoidal, and idiosyncratic making feature extraction difficult to automate. The absence of a freely available computational tool for characterizing respiratory behavior is a hindrance to many facets of olfactory and respiratory neuroscience. To solve this problem, we developed BreathMetrics, an open-source tool that automatically extracts the full set of features embedded in human nasal airflow recordings. Here, we rigorously validate BreathMetrics' feature estimation accuracy on multiple nasal airflow datasets, intracranial electrophysiological recordings of human olfactory cortex, and computational simulations of breathing signals. We hope this tool will allow researchers to ask new questions about how respiration relates to body, brain, and behavior.

Counseling by epileptologists affects contraceptive choices of women with epilepsy

INTRODUCTION

There are several important interactions between antiepileptic drugs (AEDs) and hormonal contraception that need to be carefully considered by women with epilepsy (WWE) and their practitioners. Many AEDs induce hepatic enzymes and decrease the efficacy of hormonal contraception. In addition, estrogen-containing hormonal contraception can increase the metabolism of lamotrigine, the most commonly prescribed AED in women of childbearing age. The intrauterine device (IUD) is a highly effective form of reversible contraception without AED drug interactions that is considered by many to be the contraceptive of choice for WWE. Women with epilepsy not planning pregnancy require effective contraceptive counseling that should include discussion of an IUD. There are no guidelines, however, on who should deliver these recommendations. The objective of this study was to explore the hypothesis that contraceptive counseling by a neurologist can influence the contraceptive choices of WWE. In particular, we explored the relationship between contraceptive counseling in the epilepsy clinic and the likelihood that patients would obtain an IUD.

METHODS

We conducted a retrospective chart review of female patients age 18-45 seen at our institution for an initial visit between 2010 and 2014 to ascertain the type of contraceptive counseling each patient received as well as AED use and contraceptive methods. Patients who were pregnant or planning pregnancy at the first visit were excluded from further analyses as were patients with surgical sterilization. We also examined a subgroup of 95 patients with at least 4 follow-up visits to evaluate the efficacy of epileptologists' counseling. Specifically, we looked at the likelihood a patient obtained an IUD based on the type of counseling she had received. Fisher exact tests assessed associations between counseling type and whether patients had obtained an IUD.

RESULTS

Three hundred and ninety-seven women met criteria for inclusion. Only 35% of female patients were counseled about contraception at the first visit. If women were not counseled at the first visit, they were unlikely to be counseled at subsequent visits; only 37% had ever received counseling by their fourth visit. Of the 95 patients who completed 4 visits, 28.4% were counseled about an IUD as an optimal contraceptive choice, 38.9% were generally counseled about contraceptive interactions, and 32.6% were not counseled about contraception. Women with epilepsy who received IUD-specific counseling were significantly more likely to switch to an IUD (44.4%) compared with women who received no contraceptive counseling (6.5%; p=0.0009). Women with epilepsy who received IUD-specific counseling also tended to switch to an IUD more often than those women receiving general counseling about AEDs and contraceptive interactions (18.9%; p=0.027). There was no significant difference in the likelihood of acquiring an IUD between the general counseling and no counseling groups.

CONCLUSIONS

Contraceptive counseling by epileptologists and specific mention of an IUD is significantly associated with patient selection of an IUD as a contraceptive method. This suggests that neurologists can play an important role in patients' contraceptive choices.

Anatomy of the paranasal sinuses

This article portrays the anatomy of the ethmoid bone and lateral nasal wall in a detailed, but easily digested form. Understanding the anatomy of the lateral wall of the nose is the cornerstone of competent paranasal sinus surgery.

Suprahyoid and inferior constrictor release for laryngeal lowering

OBJECTIVE

To quantify accurately the suprahyoid and inferior constrictor releases, which are used to decrease tension across a tracheal anastomosis performed after tracheal resection.

DESIGN

Intraoperative tension measurements at 0.5-cm intervals of the released laryngotracheal unit were obtained using a spring balance after division of the trachea.

SUBJECTS

A selected series of eight patients undergoing total laryngectomy for laryngeal carcinoma, excluding those with cervical soft-tissue involvement, tongue-base involvement, or a history of radiation therapy to the head and neck.

RESULTS

The suprahyoid and inferior constrictor releases together permit a tension-free, inferior displacement of 2 cm. The suprahyoid release alone permits an inferior laryngotracheal displacement of 3.5 cm without exceeding the critical, anastomotic failure tension of 1700 g. Using the releasing techniques together permits inferior displacement of 4 cm without notably exceeding this critical tension.

CONCLUSIONS

The closure of 2-cm defects without a releasing procedure is supported by this study. Larger defects of 3.5 cm, and occasionally 4 cm, can be closed safely without exceeding the critical tension level using a suprahyoid release. This study supports the use of the suprahyoid and inferior constrictor releases together for the uncomplicated closure of 4-cm defects.

The sinking bullet

We report a case of a missile injury to the brain with an unusual complication. The bullet migrated by its mere weight to a distant location through the brain parenchyma after it initially lodged in a superficial site. Instances of similar phenomena reported in the literature are reviewed.

Injuries of the external ear

Ear injuries occur in people of all ages but predominate in active people such as wrestlers, boxers, and bike riders. The types and extent of injury are a function of the force causing the injury. Shearing forces of moderate intensity cause hematoma formation, whereas greater force causes lacerations or even amputation. Sharp objects cause lacerations determined by the force, direction, and point of impact. The high ratio of surface area to mass makes the auricle vulnerable to extremes of temperature. People participating in high-risk activities should wear protective headgear. The goal of treatment is to restore the normal contours while preventing infection. Hematoma results in disfigurement by organization or chondritis. Evacuation and pressure dressings using sterile technique correct the condition. Second-degree burns are treated by regular cleansing and application of topical antimicrobials. Deeper burns require debridement, biologic dressings, or burying the cartilage subcutaneously for later reconstruction. Simple lacerations are closed under aseptic technique using either skin-to-skin sutures only or sutures of the skin combined with intercartilage sutures. Extensive and complex lacerations require meticulous care to match all fragments and prevent infection or loss of tissue. Bare cartilage must be covered with vascularized tissue. The treatment of total amputation is controversial. Some advocate reattachment as a composite graft using intravenous low molecular weight dextrans and heparin as adjuvants. Mladick dermabrades the amputated pinna, reattaches it with sutures, and then slips it into a pocket of elevated postauricular skin for 2 weeks. Others urge microvascular reanastomosis of the small nutrient vessels. Brent and Byrd separate the cartilage from its overlying skin and envelope it first with vascularized temporoparietal fascia and then a split-thickness skin graft. Chondritis is the most feared complication of injury or surgery of the pinna. It is an aggressive process, and prompt removal of pus and necrotic cartilage is required. Exteriorization and removal of all cartilage is effective but disfiguring. Removal of only affected cartilage and constant irrigation with antibiotic solutions is effective but requires prolonged hospitalization. Iontophoresis of antibiotics into the auricle may be effective and conserve tissue. Traumatic deformities are corrected with composite grafts from the opposite ear, costal cartilage, and local pedicled flaps.(ABSTRACT TRUNCATED AT 400 WORDS)

Nasal spine suspension for reduction and immobilization of mandibular fractures

Successful treatment of mandibular fractures involves proper fracture reduction and immobilization for an adequate length of time. A simple wire fixation technique that can be used in many situations involves suspension wiring from the base of the anterior nasal spine to a pair of circummandibular wires. The technique may be used alone or adjunctively with other methods of fixation. It offers several advantages over other methods, particularly in the treatment of pediatric mandibular fractures.

Coordinated electrical pacing of vocal cord abductors in recurrent laryngeal nerve paralysis

Electrodes were placed into the posterior cricoarytenoid and diaphragmatic muscles of five tracheostomized dogs. With the use of a sensor that would selectively detect diaphragmatic electromyographic activity, this activity served as a trigger and was amplified and interfaced with a muscle stimulator attached to electrodes placed in the posterior cricoarytenoid muscles. In all animals obvious physiologic synchrony of vocal fold abduction and a reduction of the negative inspiratory intratracheal pressure were observed during electrical pacing. This represents a preliminary step in the development of an alternative approach to the patient with bilateral recurrent laryngeal nerve paralysis.

Temporalis pericranial muscle flap for reconstruction of the lateral face and head

Large ablative surgical tissue defects of the lateral face and head can pose a difficult task for the reconstructive surgeon who must choose from among a large variety of possible reparative techniques. In many situations the temporalis pericranial muscle flap offers the outstanding feature of providing a large amount of soft tissue at no direct expense of donor site skin cover. It is easily obtained and results in negligible functional loss. With care taken to preserve the neurovascular pedicle, this flap may be rotated in multiple directions and even overturned as either surface can receive surface skin closure. The amount of operative time and effort required is much less than for many of the more elaborate reconstructive flaps. Five representative cases are presented.

Skin grafts: the "unsuture' technique

Small skin grafts are often the most appropriate treatment of skin defects on the face, as in the areas of the nasal tip and the anterior surface of the auricle. An improved technique for suturing the graft and applying the stent is described that uses rapidly absorbed 6-0 mild chromic sutures and a protective stent that is taped in a radial fashion. This technique has proved to yield appropriate graft results as well as avoiding a number of the inconveniences of traditional grafting and stent methods.

Congenital laryngeal stridor secondary to flaccid epiglottis, anomalous accessory cartilages and redundant aryepiglottic folds

Most laryngeal anomalies are supraglottic and laryngomalacia is the most common. Cysts, bifid epiglottis and absence of the epiglottis are uncommon. An 18-year-old Caucasian man had long-standing stridor caused by anomalous supraglottic structures: a small floppy epiglottis, enlarged accessory cartilages and redundant aryepiglottic folds. These structures were excised and the airway was improved. The ventral portions of the fourth arches become the aryepiglottic folds and lateral segments of the epiglottis. A disturbance in this portion of the fourth arch may explain the anomaly. The cartilaginous contributions to the epiglottis were possibly isolated as accessory cartilages. Epiglottic anomalies may be associated with other anomalies, especially the digits of the hand. This patient had a short lingual frenulum and mild macroglossia.

Metastatic cervical adenocarcinoma from unknown primary tumor. Treatment dilemma

Adenocarcinomas with cervical metastases as their only manifestation are infrequent. They have been grouped with metastatic squamous carcinomas of unknown primary tumor in the ear, nose, and throat literature. Most cases represent distant metastases and will have a rapid downhill course to death despite all treatment. A diligent search should be made for treatable adenocarcinomas, eg, breast, ovary, prostate, and thyroid. The primary site will be found in only a small minority of cases by any means. Radical neck dissection should not be performed when the primary tumor is not localized to the head and neck.

Soft tissue facial trauma

Treatment of soft tissue facial trauma requires attention to detail. Careful cleansing, debridement, tailoring of skin edges and meticulous closure are factors which control the ultimate result. Specific attention is required for the special problems of eyelids, auricles, lips, nose and inside of the mouth. Scar formation occurs after all trauma and sometimes requies revision. In general, revision should be performed after maturation of the scar.

Leiomyoma of the maxilla - report of a case

Leiomyoma is a rare tumor in this location. It probably arises from the tunica media of blood vessels. Electron microscopy is necessary to confirm the diagnosis. Local excision of the lesion is adequate treatment.

Recurrent laryngeal nerve localization using a microlaryngeal electrode

Damage to the recurrent laryngeal nerve is a frequently seen complication in head and neck surgery. A system for intraoperative monitoring of the recurrent laryngeal nerve is presented. The key to this system lies in the use of a microlaryngeal electrode and inserter. Application of this system to various situations is described.

Aspiration cytology for diagnosis of head and neck masses

Most American clinicans have been relectant to utilize aspiration biopsy due to poor interpretive skills by the pathologists in the past and a fear of tumor spread by the needle. Voluminous European series and recent American series have proved aspiration to be safe and reliable. In our series of 78 cases, both thin-needle aspiration and conventional tissue biopsies were made. The diagnoses were compared and the overall agreement rate was 90%.