David Boorman

Complications of subdural and depth electrodes in 269 patients undergoing 317 procedures for invasive monitoring in epilepsy

Intracranial monitoring is fundamental to epilepsy surgery, with reported complication rates of 3–17%. We aimed to assess the differences in complication rates between subdural and depth electrodes.

The effects of anatomic variations on stereotactic laser amygdalohippocampectomy and a proposed protocol for trajectory planning.

BACKGROUND: Stereotactic laser amygdalohippocampectomy (SLAH) is a promising minimally invasive alternative for mesial temporal lobe epilepsy. As seizure outcome has been associated with the extent of amygdalar and hippocampal ablation, it is important to select a safe trajectory optimizing involvement of both structures; however, variations in temporal anatomy significantly affect the overall complexity of planning. OBJECTIVE: To quantify anatomic variables of SLAH and facilitate stereotactic planning by developing a protocol for optimally targeting the amygdalohippocampal complex (AHC). METHODS: We performed a retrospective analysis of 19 SLAHs. Anatomic measurements from preoperative magnetic resonance imaging and laser trajectory measurements from coregistered postoperative magnetic resonance imaging were taken in 11 patients. Simple linear regression analysis was performed to identify significant predictor variables determining ablation extent. Based on these data, a protocol for optimal trajectory planning was developed and subsequently implemented in 8 patients. RESULTS: The medial angle of the laser trajectory correlated with the medial angle of the AHC. The length of amygdalar cannulation was predictive of its ablation volume. All trajectories passed through a posteroinferior corridor formed by the lateral ventricle superiorly and collateral sulcus inferiorly. Our protocol facilitated planning and increased the volume of AHC ablation. CONCLUSION: The medial AHC angle dictates the medial trajectory angle and a path from the posteroinferior corridor through the hippocampus and the center of the amygdala dictates the caudal angle. These observations led to a protocol for long-axis AHC cannulation that maintains an extraventricular trajectory to minimize hemorrhage risk and targets the center of the amygdala to optimize ablation volumes. ABBREVIATIONS: AHC, amygdalohippocampal complex MTLE, mesial temporal lobe epilepsy SLAH, stereotactic laser amygdalohippocampectomy

Long-Term Pain Reduction Does Not Imply Improved Functional Outcome in Patients Treated With Combined Supraorbital and Occipital Nerve Stimulation for Chronic Migraine.

Dual supraorbital and occipital nerve stimulation (SONS and ONS) have shown promising efficacy in treating primary headaches. However, its functional outcome is not well studied.

189 Comparison of Efficacy of Tonic and Burst Occipital Nerve Stimulation in Treating Trigeminal Allodynia: Chronic Result.

INTRODUCTION Burst stimulation is a new paradigm that eliminates paresthesias typically observed with traditional tonic stimulation. We used a rodent model of episodic migraine to compare the efficacy of tonic and burst stimulation in treating trigeminal allodynia. METHODS Twelve Sprague-Dawley rats with spontaneous trigeminal allodynia1 were implanted with miniaturized paddle leads over the occipital nerves, and the leads connected to a pulse generator located dorsally. Rats were randomly assigned to receive 4 frequencies: tonic 60 Hz, tonic 500 Hz, burst 40 Hz, and burst 50 Hz. Tonic 500 Hz and burst 50 Hz were the most effective parameters on short-term trials conducted previously. Tonic 60 Hz and burst 40 Hz are the most common parameters in clinical use. After establishing baseline hypersensitivity, the stimulation was turned ON for 10 days, followed by OFF for 10 days. Daily periorbital sensitivity was assessed using von Frey filaments (VFF). Rats were characterized as hypersensitive or as responders when VFF thresholds were 4 g or 6 g, respectively. Analysis of variance tests were used for analysis. RESULTS Overall, both tonic and burst ONS significantly improved VFF thresholds compared with baseline (P < .005). Tonic stimulations had a superior response (P = .022) on day 1, but the burst stimulations produced superior efficacy from day 3. On 3, 4, 6, and 9 of ON days, there were statistically superior reduction of allodynia observed for burst stimulations. After the stimulation was turned OFF on day 10, tonic stimulations lost efficacy sooner, whereas burst stimulations had a trend in maintaining superior efficacy for an additional day (day 11, P = .053). CONCLUSION Tonic stimulation had superior take-off efficacy, but there was a latent positive response associated with burst stimulation that made it superior to tonic stimulation. In addition, burst stimulations exhibited a better therapeutic carryover effect that lasted for a day after stimulation was OFF. Human trials of burst stimulation for headache disorders are warranted to clinically validate our results.

High-Resolution Pulse Oximetry (HRPO): A Cost-Effective Tool in Screening for Obstructive Sleep Apnea (OSA) in Acute Stroke and Predicting Outcome

INTRODUCTION Obstructive sleep apnea (OSA) is a well-known risk factor for stroke. This is attributed to multiple mechanisms such as endothelial dysfunction, atrial fibrillation, hypertension, and comorbid obesity. STOP questionnaire alone is unreliable to diagnose OSA and in-hospital sleep study is costly and can be technically challenging. We used high-resolution pulse oximetry (HRPO) to test the feasibility of screening for OSA and predicting outcome. METHODS Data from 115 stroke patients who underwent HRPO was collected including Oxygen desaturation index (ODI) <4%, pulse rate, arterial oxygen saturation (SaO2), and time spent at SaO2 saturation <88%. We also collected data on various confounders. The outcomes measured were NIHSS (National Institutes of Health Stroke Scale), mRS (modified Rankin Score) on discharge, and discharge disposition. RESULTS Overall 115 patients with valid HRPO data were included in the study. Mean age was 64±12years with 68% white, 22% black, and 10% Hispanic population. Of this cohort of 115 patients, 56% were males. Of the subjects enrolled 22 had atrial fibrillation, 27 had type 2 diabetes, 7 had resistant hypertension, and 7 had patient foramen ovale. Of the 115 patients, 75 patients were found to have ODI of >10 and the mean ODI was 29±30. The NIHSS on admission was 6.14±6.93 and on discharge was 4.46±4.59, mRS on discharge was 1.70±1.67 with 52% being discharged home, 43% to rehab, 2% nursing home, and 3% to long-term acute care facility. In this study, we show a strong association between atrial fibrillation and increasing ODI (P<.001, OR 1.01, CI 1.00-1.03). In addition, our study also shows an association between discharges outcome of rehab (more deficits leading to higher disability) versus discharge to home (lesser deficits) if ODI was ≤10 (P = 0.005, OR 3.76, CI 1.49-9.52). CONCLUSIONS Our study showed that there is a significant burden of OSA in acute stroke patients. ODI emerged as a predictor of atrial fibrillation and discharge disposition in our study. HRPO may be a cost-effective tool to screen and evaluate for OSA in acute stroke patients.

758: CAN PROCALCITONIN DIFFERENTIATE BETWEEN CENTRAL AND INFECTIOUS FEVER IN PATIENTS WITH ICH

Crit Care Med 2016 • Volume 44 • Number 12 (Suppl.) median dose of 4FPCC in the SD and HD groups was 25 units/kg and 50 units/ kg, respectively. The repeat INR post 4FPCC in the SD was 1.2 [1.2–1.3] and 1.1 [1.1–1.2] in the HD 4FPCC group (p=0.19). No difference was observed in achieving an INR of 1.3 or less when comparing the HD and SD 4FPCC groups (77 vs 82%, p=0.72). Hematoma expansion occurred equally in both groups at 13% (p=0.96). Lastly, in the HD group, there was one thrombotic event reported vs none in the SD group. Conclusions: Administering SD or HD 4FPCC to patients with WICH effectively lowered the INR to 1.3 or less in most patients. HD 4FPCC was not associated with a significant increase in thrombotic events. Further studies are warranted to evaluate the impact of HD 4FPCC on functional outcomes and mortality.

445: SAFETY AND EFFICACY OF A SHORTENED FASTING TIME FOR MECHANICALLY VENTILATED PATIENTS

Crit Care Med 2016 • Volume 44 • Number 12 (Suppl.) in 2015. Results: The study population included 55 patients (83% new onset) with a median age of 55 months (105-188) and weight of 44.5 kg (22.5-56). On admission, patients had a median venous pH of 7.06 (6.96-7.15), mean bicarbonate of 5 mmol/L (±2.1), anion gap (AG) of 25 (±5.7), and hemoglobin A1c of 12.7 % (±2.1). During DKA management, patients received a median chloride load (CL) of 606.8 mEq (357.8-767.7). It took a median of 8 hours (4-8) for the AG to normalize and an additional 8 hours (3-14) for overall acidosis to resolve. There was a significant positive correlation between CL from IVF and duration of overall acidosis (rs = 0.391, p<0.01) and CL and duration of acidosis after the AG normalized (rs=0.318, p=0.01). After adjusting for age, initial pH and hemoglobin A1c, the chloride load from 1L of 0.9% normal saline was associated with an increased duration of acidosis of 4.6 hours (95%CI 2.5-6.5; p<0.01). After adjusting for age and initial pH, having a serum chloride level over 120 mEq/dL increased the hospital length of stay by 0.33 days (95%CI 0.14-1.54; p=0.02). Conclusions: The iatrogenic chloride load from DKA management is associated with prolongation of acidosis well after the anion gap normalizes and elevated serum chloride prolongs length of stay. Further research to evaluate the potential for shortening of the duration of acidosis and overall length of stay in children with DKA by changing the chloride content of IV fluids administered needed.