Scheherazade Le

Gelastic epilepsy and hypothalamic hamartomas: neuroanatomical analysis of brain lesions in 100 patients

Hypothalamic hamartomas present with isolated fits of ictal laughter (gelastic epilepsy) or a combination of gelastic and other types of seizures. Many of these patients also suffer from cognitive decline, neuropsychiatric comorbidities and precocious puberty. Although there is a large body of anecdotal evidence about hypothalamic hamartomas and gelastic seizures, many questions still remain to be answered. For instance, which specific hypothalamic regions are most affected by the location of hamartomas causing laughing versus other types of seizures? Does the neuroanatomical localization of the lesions differ in cases with only gelastic seizures or a combination of gelastic and other types of seizures? Does the location of the lesions correlate with the presence of precocious puberty, and does the type of lesion influence the severity or the type of seizures? In a retrospective review of clinical and structural neuroimaging data from 100 cases of gelastic epilepsy and hypothalamic hamartoma, we aimed to address these questions by analysing the clinical presentation and the neuroanatomical features of the hypothalamic lesions in these patients. Our findings suggest that in all 100 cases, lesions were centred at the level of the mammillary bodies in the posterior hypothalamus. Compared with the patients with pure gelastic seizures (n = 32), those with gelastic and other types of seizures (n = 68) had significantly longer duration of epilepsy (P < 0.001), whereas age of seizure onset, the volume of lesions and the proximity to the mammillary bodies were not different between the two groups. In contrast, patients with cognitive or developmental impairment and those with precocious puberty had significantly larger lesions involving the anterior and posterior hypothalamus.

An online diary for tracking epilepsy

My Epilepsy Diary is a free Web-based application on the public website epilepsy.com, available for patients to track epilepsy and to aid clinicians with data-based, individualized management. The first aim of this descriptive study was to outline electronic diary functions. Second, the study retrospectively profiled a large cohort of 2010 calendar year diary users including demographics, seizure types, temporal distribution of seizures, triggers, and use and side effects of antiepileptic drugs (AEDs). A total of 1944 users provided demographic information and 1877 recorded seizure data. Most (64%) users were women. Average age was 29.9±16.0 years. A total of 70,990 seizure entries and 15,630 AED entries were logged. Events were apportioned as 79% seizures and 21% seizure clusters. Specific AEDs were detailed in 7331 entries: monotherapy was used in 18% and polytherapy in 82%. Mood-related side effects were most commonly reported in 19% of 1027 users.

Improved operative efficiency using a real-time MRI-guided stereotactic platform for laser amygdalohippocampotomy

OBJECTIVE MR-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive method for thermal destruction of benign or malignant tissue that has been used for selective amygdalohippocampal ablation for the treatment of temporal lobe epilepsy. The authors report their initial experience adopting a real-time MRI-guided stereotactic platform that allows for completion of the entire procedure in the MRI suite. METHODS Between October 2014 and May 2016, 17 patients with mesial temporal sclerosis were selected by a multidisciplinary epilepsy board to undergo a selective amygdalohippocampal ablation for temporal lobe epilepsy using MRgLITT. The first 9 patients underwent standard laser ablation in 2 phases (operating room [OR] and MRI suite), whereas the next 8 patients underwent laser ablation entirely in the MRI suite with the ClearPoint platform. A checklist specific to the real-time MRI-guided laser amydalohippocampal ablation was developed and used for each case. For both cohorts, clinical and operative information, including average case times and accuracy data, was collected and analyzed. RESULTS There was a learning curve associated with using this real-time MRI-guided system. However, operative times decreased in a linear fashion, as did total anesthesia time. In fact, the total mean patient procedure time was less in the MRI cohort (362.8 ± 86.6 minutes) than in the OR cohort (456.9 ± 80.7 minutes). The mean anesthesia time was significantly shorter in the MRI cohort (327.2 ± 79.9 minutes) than in the OR cohort (435.8 ± 78.4 minutes, p = 0.02). CONCLUSIONS The real-time MRI platform for MRgLITT can be adopted in an expedient manner. Completion of MRgLITT entirely in the MRI suite may lead to significant advantages in procedural times.

A New Association Between Castleman Disease and Immune-Mediated Cerebellitis

Report of a Case | A previously healthy man in his 30s awoke one morning with acute, extreme vertigo; unsteady gait; and dyscoordination. His symptoms progressed despite treatment with diazepam and meclizine, and he presented to our hospital 1 month after symptom onset unable to walk or feed himself. Neurologic examination was significant for oscillopsia, nystagmus in all directions of gaze, scanning speech, and profound truncal and appendicular ataxia. He could neither stand nor ambulate owing to imbalance. Institutional review board approval was not obtained because it is not required for case reports at our institution; the patient provided oral consent. Brain magnetic resonance imaging revealed leptomeningeal enhancement between the cerebellar folia (Figure 1A). Cerebrospinal fluid tests revealed white blood cell count of 16/μL (96% lymphocytes) (to convert white blood cell count to ×109 per liter, multiply by 0.001), red blood cell count of less than 1 ×106/μL (to convert to ×1012 per liter, multiply by 1.0), and normal protein and glucose levels; viral, fungal, and bacterial culture results were negative (including varicellazoster virus, herpes simplex virus types 1 and 2, enterovirus, Lyme, and cryptococcus); and oligoclonal bands, cytology, and flow cytometry were unremarkable. Cerebrospinal fluid test results were negative for autoantibodies to antineuronal nuclear antibody 1 (anti-Hu), antineuronal nuclear antibody 2 (anti-Ri), antineuronal nuclear antibody 3, antiglial nuclear antibody 1, Purkinje cell cytoplasmic antibody type 1 (antiYo), Purkinje cell cytoplasmic antibody type 2, amphiphysin, and collapsin response mediator protein 5 (anti-CV2). Serum paraneoplastic panel results were negative, which included the same cerebrospinal fluid antibodies plus anti-Ma1, anti-Zic4, anti-GAD65, Purkinje cell cytoplasmic antibody type Tr, P/Qand N-type calcium channel antibodies, voltage-gated potassium channel, N-methyl-D-aspartate receptor, and acetylcholine receptor antibodies. Serum studies revealed only an isolated elevated interleukin 6 level at 26 pg/mL (normal, <5 pg/mL). Results from human immunodeficiency virus RNA polymerase chain reaction and human herpesvirus 8 IgG and DNA testing were negative. Computed tomographic scans of the chest, abdomen, and pelvis found multiple anterior mediastinal soft-tissue nodules that were metabolically active on positron emission tomography with fluorodeoxyglucose. Thymic and lymph node biopsies confirmed the diagnosis of hyaline vascular Castleman disease (Figure 2). The patient underwent treatment with intravenous immunoglobulin for 5 days (0.4 g/kg/d), followed by 1 g intravenous solumedrol daily for 5 days along with intensive physical, occupational, and speech therapy but failed to improve clinically. The mediastinal mass was resected on hospital day 16, and repeated magnetic resonance imaging 3 weeks after presentation (6 days postresection) showed resolution of cerebellar enhancement and subtle cerebellar degeneration (Figure 1B). He was discharged to a rehabilitation facility and, at 6-month follow-up, remained wheelchair dependent with persistent ataxia and diplopia. He was lost to follow-up before more aggressive treatment could be instituted.

Laser interstitial thermal therapy (LITT): Seizure outcomes for refractory mesial temporal lobe epilepsy

BACKGROUND Laser interstitial thermal therapy (LITT) is a minimally invasive alternative with less cognitive risks compared with traditional surgery for focal drug-resistant epilepsy. OBJECTIVE We describe seizure outcomes and complications after LITT in our cohort with intractable mesial temporal lobe epilepsy (MTLE). MATERIAL AND METHODS We prospectively tracked Stanfords MTLE cases treated with LITT from October 2014 to October 2017. Primary endpoints were seizure outcomes by (1) Engel classification and (2) reduction in baseline seizure frequency. Secondary outcomes were postablation complications. RESULTS A total of 30 patients underwent selective amygdalohippocampotomy via LITT. Mesial temporal sclerosis (MTS) was present in 23/30 (77%) patients. Median follow-up was 18 ± 12 months (range: 6-44 months). Almost all 28/29 (97%) patients had >50% reduction, and 22/29 (76%) patients had >90% reduction in seizure frequency. Engel Class I outcome was achieved in 18/29 (62%) patients; with complete seizure freedom in 9/29 (31%) patients (Engel Class IA). Three (10%) patients have had only focal aware seizures (Engel Class 1B). Seizures only occurred with medication withdrawal in 6/29 (21%) patients (Engel Class ID). Class II was achieved by 6/29 (21%) and Class III by 5/29 (17%) patients. Complications included perioperative seizures in 10/29 (34%) and nonseizure complaints in 6/29 (21%) patients. Three (10%) patients had neurological deficits including one permanent superior quadrantanopsia, one transient trochlear, and one transient oculomotor nerve palsy. CONCLUSIONS Overall, Engel Class I outcome was achieved in 62% of patients with MTLE, and 97% of patients achieved >50% seizure frequency reduction. Complications were largely temporary, though there was one persistent visual field deficit. Laser ablation is well-tolerated and offers marked seizure reduction for the majority of patients.

F113. The methohexital challenge prior to intracranial endovascular embolization

Introduction The risks associated with endovascular embolization procedures are both mitigated and predicted with the use of pharmacologic provocative testing (PT) and intraoperative neurophysiologic monitoring (IONM). The utility of pharmacologic provocative testing has been reviewed in the literature, mostly in patients undergoing awake procedures with the use of neurologic examination and electroencephalogram. Here, we review our experience in patients undergoing intracranial endovascular embolization procedures with the use of IONM. Methods We reviewed our database to identify all patients undergoing endovascular procedures between January 1, 2014 and January 1, 2016. We included only patients who underwent cerebral endovascular embolization procedures with the use of methohexital PT. A retrospective chart review was performed to identify patients’ demographic factors, intraoperative findings, and postoperative examination details. We also reviewed perioperative notes to identify any adverse reactions to methohexital as well as other complications unrelated to the use of methohexital. Awake patients were tested with SSEP, EEG and real time neurologic examination while TcMEPs were performed in all anesthetized patients. BAEPs were performed in anesthetized patients if indicated. Methohexital was administered as an injection at a dose of 5 mg or 10 mg and repeat testing was performed if needed. Results A total of 64 endovascular procedures were performed in 31 patients with utilization of pharmacologic PT and were included in this review. PT was performed under general anesthesia in 54 procedures (84%) and awake testing was performed in 10 procedures (16%). PT was negative in 62 procedures and embolizations were performed in these patients. PT was positive in two procedures and the procedure was terminated without embolization in one patient. The other patient underwent embolization after repositioning the catheter at an alternative embolization site but repeat testing was not performed. There were no new postoperative neurologic deficits after any of these procedures. We calculated the specificity of pharmacologic PT as 100% as none of the patients with a negative provocative test developed a new postoperative neurologic deficit after embolization. Conclusion To the best of our knowledge, this is the first review on pharmacologic PT with methohexital and with the use of IONM under general anesthesia. Our results also indicate that IONM under general anesthesia can allow pharmacologic PT at a specificity comparable to awake testing. We also postulate that the absence of false negatives provides strong evidence that IONM accurately monitors the functional state of the brain during PT. If this were not the case, then new neurologic deficits should be seen in some of the cases with negative tests.

F111. Isolating C8 nerve root technique with focal digital stimulation

Introduction The American Clinical Neurophysiology Society guidelines recommend eliciting upper extremity somatosensory evoked potentials (SSEP) via median or ulnar nerve stimulation at the wrist. However, when monitoring cervical spine surgeries, it may be more appropriate to use ulnar nerve stimulation as the root contribution to the cortical SSEP originates at levels below C7, while median nerve SSEPs have contributions possibly as high as C5. We postulate that wrist stimulation reflects a combination of activated axons from both the median and ulnar nerves secondary to supramaximal stimulation typically used intraoperatively. It’s therefore difficult to precisely determine the level of SSEP nerve root entry. Isolated ulnar stimulation targeting only C8-T1 roots could remedy this issue. The authors tested the feasibility and reliability of pure ulnar C8-T1 activation through 5th digit stimulation. Methods This prospective study consented and enrolled eight patients without known evidence of peripheral neuropathy or cervical radiculopathy undergoing routine intraoperative neurophysiologic monitoring (IONM) including SSEP. Standard adhesive gel electrodes were used for wrist stimulation over the median and ulnar nerves, as well as the 5th digit. Ulnar nerve stimulating electrodes were placed at the wrist and 5th digit on the contralateral side of arterial line placement. Cortical SSEPs (montage of CPc-Fz and CPc-CPi) were analyzed for amplitude, latency and morphology. The intensity, pulse width, and repetition rate of stimulation to elicit the SSEP were also analyzed. SSEPs were obtained throughout surgery to ensure reproducibility. Results Stimulation of the median nerve at the wrist provided the highest amplitude cortical SSEP. Signals were consistently present in the ulnar nerve at wrist and 5th digit for each patient. The mean ulnar nerve amplitudes at the wrist and 5th digit were 42% and 78% smaller compared to the median amplitude, respectively. The average percent standard deviation of amplitudes for median nerve SSEP was 13.42% compared to 17.87% and 17.35% from ulnar nerve at the wrist and 5th digit, respectively. Conclusion These data confirm 5th digit stimulation may be a reproducible method of isolating C8-T1 root activation. Despite higher amplitude responses from median wrist stimulation, 5th digit ulnar stimulation remained consistent during surgical procedures and could be used to detect conduction changes. This technique avoids coactivation of the median nerve SSEP which can occur when stimulating for an ulnar nerve SSEP at the wrist, thereby preventing false negative responses. This was further confirmed during this study by the identification of a case, which was subsequently excluded from analysis, of a patient determined to have a preexisting ulnar neuropathy, diagnosed by outpatient nerve conduction studies. Intraoperative cortical SSEP was correctly absent from 5th digit stimulation and incorrectly present from wrist stimulation of the ulnar nerve in this patient.

S116. Transient intraoperative peripheral nerve injury precipitated by rare iatrogenic lapse

Introduction Intraoperative neuromonitoring primarily tracks for disruptions of the neuraxis during cerebral surgical procedures. Occasionally, peripheral injury can mimic central injury. We report a case where an iatrogenic lapse triggered transient peripheral injury. Methods A 4 year old boy was diagnosed with a left-sided arteriovenous malformation and underwent cerebral angiogram with embolization. While acquiring vascular access to begin the procedure, the endovascular neurosurgeon advanced the femoral sheath into the right femoral artery towards the level of right common iliac artery and the distal aorta. Prior to guidewire insertion, the surgeon flushed the femoral sheath with heparinized saline to prevent blood clot formation. Within a few minutes, there was a significant right lower extremity somatosensory evoked potential (SSEP) amplitude decline of greater than 50%. Review of the SSEP traces displayed a decrease in both the cortical and peripheral potentials (popliteal fossa and C7), indicating a likely peripheral cause of the change. The surgeon was informed of the peripheral cause of the SSEP change, but no etiology was readily identified. Additional detailed investigation identified the saline flush being infused at a high rate into the right leg, instead of the typical rate of 1–2 drops per second. The flush was closed after an approximate total infused volume of 1000 mL. After closure of the flush, the lower extremity SSEP returned to baseline within a few minutes. The procedure continued and was completed without any other adverse events. He was neurologically intact postoperatively. Results This case provides an example of how the nervous system is at risk throughout a procedure, even during ”non-critical” periods when neurologic injury is not expected to occur. By quickly identifying and investigating neurophysiologic changes, the clinical team was able to correct a rare iatrogenic cause of peripheral limb ischemia and avoid potential complications or neurologic injury. Conclusion While infrequent, neurologic dysfunction and permanent damage may occur during the initial phases of any surgical procedure while positioning, access, or exposure is occurring. The etiology of these neurologic changes may not always be immediately recognizable and should encourage early and effective communication between the neurophysiologist, anesthesiologist, and surgeon.

T92. Diversity in clinical practice of “Continuous” intraoperative neurophysiologic monitoring (IONM)

Introduction Despite advances in neurophysiologic techniques and increased utilization of IONM across a wide diversity of surgical cases, there remain no formal guidelines or consensus about best practice parameters in the implementation of “continuous” monitoring. As critical IONM changes may occur at any time during a surgical procedure, even during “non-critical” periods, variations in total duration of neuromonitoring as well as frequency of evoked potential (EP) acquisition may adversely impact timely and reliable interpretation and communication of such neurophysiologic changes to the surgical team. It is our goal to evaluate the potential variability of IONM practice in both private and academic settings. Methods A practice survey was administered to attendees of the IONM Special Interest Group sessions at the annual ACNS meetings in 2016 (Part I) and 2017 (Part II). This included multiple choice as well as open-ended questions on topics such as the frequency of somatosensory and transcranial motor evoked potential (SSEP and tcMEP) acquisition in the OR, appropriate “start” and “end” times of neuromonitoring, effective communication between the IONM and surgical teams, as well as the number of simultaneous cases that are confidently monitored, and issues related to job satisfaction. These findings are summarized here. Results A total of 35 surveys were returned in 2016 and 30 surveys in 2017, respondents comprising IONM providers in academic, private, and mixed practices. The most popular answer for frequency of SSEP acquisition was every 3–5 min (48%), followed by every 5–7 min (23%). Most common responses regarding frequency of tcMEP acquisition were every 10–15 min (43%) followed by every 5–7 min (25%). Regarding the appropriate duration of an incision/exposure break, answers were especially variable, ranging from zero, to however long it takes to complete exposure (even if that exceeds 30 min). When asked about the maximum number of cases that are simultaneously monitored, responses also varied widely, ranging from 1 to 10 or more. For the question asking how many cases IONM providers felt comfortable monitoring simultaneously, the most common responses ranged from 1 to 6. The most frequent answer to the question of how many cases respondents felt confident monitoring simultaneously was 3 cases or less. A majority of respondents reported satisfaction most of the time with their current practice of IONM. Conclusion There is significant diversity in the clinical practice of IONM, including the frequency of evoked potential acquisition, duration of “continuous” neuromonitoring for a given procedure, and number of simultaneous cases monitored. By highlighting this variability across IONM providers, we are better able to evaluate clinical areas where future improvements and development of emerging practice parameters may be considered that have the potential to positively impact perioperative care and improve patient outcomes.

Positive pharmacologic provocative testing with methohexital during cerebral arteriovenous malformation embolization

A middle-aged patient underwent staged endovascular embolization of a Spetzler-Martin grade V right parietal arteriovenous malformation(AVM).In the fifth endovascular embolization, after methohexital 10 mg injection into a right posterior choroidal artery feeding the AVM nidus, there was an immediate change in the electroencephalogram (EEG) with simultaneous loss of motor evoked potentials (MEPs) in the bilateral upper and lower extremities and a delayed change in somatosensory evoked potential responses (SSEPs). No embolization was made and procedure was terminated. This case demonstrates the utility of intraoperative neurophysiologic monitoring (IONM) with pharmacologic provocative testing in predicting and mitigating the risks prior to the proposed embolization.