Sumeet Vadera

A new Elixhauser-based comorbidity summary measure to predict in-hospital mortality.

Background:Recently, van Walraven developed a weighted summary score (VW) based on the 30 comorbidities from the Elixhauser comorbidity system. One of the 30 comorbidities, cardiac arrhythmia, is currently excluded as a comorbidity indicator in administrative datasets such as the Nationwide Inpatient Sample (NIS), prompting us to examine the validity of the VW score and its use in the NIS. Methods:Using data from the 2009 Maryland State Inpatient Database, we derived weighted summary scores to predict in-hospital mortality based on the full (30) and reduced (29) set of comorbidities and compared model performance of these and other comorbidity summaries in 2009 NIS data. Results:Weights of our derived scores were not sensitive to the exclusion of cardiac arrhythmia. When applied to NIS data, models containing derived summary scores performed nearly identically (c statistics for 30 and 29 variable-derived summary scores: 0.804 and 0.802, respectively) to the model using all 29 comorbidity indicators (c=0.809), and slightly better than the VW score (c=0.793). Each of these models performed substantially better than those based on a simple count of Elixhauser comorbidities (c=0.745) or a categorized count (0, 1, 2, or ≥3 comorbidities; c=0.737). Conclusions:The VW score and our derived scores are valid in the NIS and are statistically superior to summaries using simple comorbidity counts. Researchers wishing to summarize the Elixhauser comorbidities with a single value should use the VW score or those derived in this study.

Minimally invasive surgical approaches for temporal lobe epilepsy

Surgery can be a highly effective treatment for medically refractory temporal lobe epilepsy (TLE). The emergence of minimally invasive resective and nonresective treatment options has led to interest in epilepsy surgery among patients and providers. Nevertheless, not all procedures are appropriate for all patients, and it is critical to consider seizure outcomes with each of these approaches, as seizure freedom is the greatest predictor of patient quality of life. Standard anterior temporal lobectomy (ATL) remains the gold standard in the treatment of TLE, with seizure freedom resulting in 60-80% of patients. It is currently the only resective epilepsy surgery supported by randomized controlled trials and offers the best protection against lateral temporal seizure onset. Selective amygdalohippocampectomy techniques preserve the lateral cortex and temporal stem to varying degrees and can result in favorable rates of seizure freedom but the risk of recurrent seizures appears slightly greater than with ATL, and it is not clear whether neuropsychological outcomes are improved with selective approaches. Stereotactic radiosurgery presents an opportunity to avoid surgery altogether, with seizure outcomes now under investigation. Stereotactic laser thermo-ablation allows destruction of the mesial temporal structures with low complication rates and minimal recovery time, and outcomes are also under study. Finally, while neuromodulatory devices such as responsive neurostimulation, vagus nerve stimulation, and deep brain stimulation have a role in the treatment of certain patients, these remain palliative procedures for those who are not candidates for resection or ablation, as complete seizure freedom rates are low. Further development and investigation of both established and novel strategies for the surgical treatment of TLE will be critical moving forward, given the significant burden of this disease.

Amygdala-hippocampal dynamics during salient information processing

Recognizing motivationally salient information is critical to guiding behaviour. The amygdala and hippocampus are thought to support this operation, but the circuit-level mechanism of this interaction is unclear. We used direct recordings in the amygdala and hippocampus from human epilepsy patients to examine oscillatory activity during processing of fearful faces compared with neutral landscapes. We report high gamma (70–180 Hz) activation for fearful faces with earlier stimulus evoked onset in the amygdala compared with the hippocampus. Attending to fearful faces compared with neutral landscape stimuli enhances low-frequency coupling between the amygdala and the hippocampus. The interaction between the amygdala and hippocampus is largely unidirectional, with theta/alpha oscillations in the amygdala modulating hippocampal gamma activity. Granger prediction, phase slope index and phase lag analysis corroborate this directional coupling. These results demonstrate that processing emotionally salient events in humans engages an amygdala-hippocampal network, with the amygdala influencing hippocampal dynamics during fear processing.

National Trends and In-hospital Complication Rates in More Than 1600 Hemispherectomies From 1988 to 2010: A Nationwide Inpatient Sample Study.

BACKGROUND Anatomic and functional hemispherectomies are relatively infrequent and technically challenging. The literature is limited by small samples and single institution data. OBJECTIVE We used the Nationwide Inpatient Sample (NIS) database to report on a large population of hemispherectomy patients and their in-hospital complication rates over a 23-year period. METHODS Between 1988 and 2010, we identified 304 pediatric hospitalizations in the NIS database where hemispherectomy was performed. Using the NIS weighting scheme, this inferred an estimated 1611 hospitalizations nationwide during this time period. Descriptive statistics were calculated on this inferred sample for patient and hospital characteristics and stratified by the presence of in-hospital complications. The adjusted odds of in-hospital complications and nonroutine discharge were estimated using multivariable models. RESULTS The mean age of the patients was 5.9 years; 46% were female, and 54% were white. In the inferred series, 909 hospitalizations (56%) encountered at least 1 in-hospital complication; 42% were surgery related, and 25% were related to the hospitalization itself. For every 1-year increase in age, there was a corresponding 8% increase in the odds of a nonroutine discharge, adjusting for other potential confounders (95% confidence interval: 1.01-1.16). The most common in-hospital complication was the need for a blood transfusion (30%), followed by meningitis (10%), hydrocephalus (8%), postoperative hematoma/stroke (8%), and adverse pulmonary event (8%). Thirty-three mortalities (2%) were inferred from this series. CONCLUSION This is the largest study to date examining hemispherectomy and associated in-hospital complication rates. This study supports early surgery in patients with medically intractable epilepsy and severe hemispheric disease.

Rare complication of ventriculoperitoneal shunt. Early onset of distal catheter migration into scrotum in an adult male: Case report and literature review

Highlights • Cases of scrotal migration of distal catheter in adults are rare.• There have been no reports for scrotal migration in adults at an early onset.• Early detection of migration of distal catheter prevents shunt malfunction.• Prompt surgical management of catheter repositioning is recommended.

National Incidence of Medication Error in Surgical Patients Before and After Accreditation Council for Graduate Medical Education Duty-Hour Reform

OBJECTIVE The Accreditation Council for Graduate Medical Education (ACGME) established duty-hour regulations for accredited residency programs on July 1, 2003. It is unclear what changes occurred in the national incidence of medication errors in surgical patients before and after ACGME regulations. DESIGN Patient and hospital characteristics for pre- and post-duty-hour reform were evaluated, comparing teaching and nonteaching hospitals. A difference-in-differences study design was used to assess the association between duty-hour reform and medication errors in teaching hospitals. SETTING We used the Nationwide Inpatient Sample database, which consists of approximately annual 20% stratified sample of all the United States nonfederal hospital inpatient admissions. PARTICIPANTS A query of the database, including 4 years before (2000-2003) and 8 years after (2003-2011) the ACGME duty-hour reform of July 2003, was performed to extract surgical inpatient hospitalizations (N = 13,933,326). The years 2003 and 2004 were discarded in the analysis to allow for a wash-out period during duty-hour reform (though we still provide medication error rates). RESULTS The Nationwide Inpatient Sample estimated the total national surgical inpatients (N = 135,092,013) in nonfederal hospitals during these time periods with 68,736,863 patients in teaching hospitals and 66,355,150 in nonteaching hospitals. Shortly after duty-hour reform (2004 and 2006), teaching hospitals had a statistically significant increase in rate of medication error (p = 0.019 and 0.006, respectively) when compared with nonteaching hospitals even after accounting for trends across all hospitals during this period. After 2007, no further statistically significant difference was noted. CONCLUSIONS After ACGME duty-hour reform, medication error rates increased in teaching hospitals, which diminished over time. This decrease in errors may be related to changes in training program structure to accommodate duty-hour reform.

Using electrocorticogram baseline seizure frequency to assess the efficacy of responsive neurostimulation

BACKGROUND The effect of direct brain responsive neurostimulation on the frequency of electrographic seizures in patients with medically refractory focal epilepsy has not been evaluated by chronic ambulatory electrocorticographic monitoring. METHODS This was a retrospective study of 9 patients who underwent implantation of the responsive neurostimulator (RNS) system from 2015 to 2017 at the University of California, Irvine. Leads were placed at the ictal onset zone as determined by intracranial electroencephalography (EEG). The neurostimulator was programmed to detect and deliver stimulation following identification of the individuals epileptiform patterns. Electrographic seizures were determined by review of all detections. The electrocorticography (ECoG) seizure frequency baseline was the average of the first 2 months postimplantation. The patient-reported seizure frequency baseline was the average of the 2 most recent months prior to RNS implantation. Seizure control was assessed at 3 months, 6 months, and 12 months. RESULTS Nine patients were included in the study. All 9 patients have been treated with responsive stimulation for at least 3 months, 7/9 for 6 months, and 4/9 for 12 months. The mean change in seizure frequency was -10%, -19%, and -56% at 3, 6, and 12 months, respectively, using a self-reported seizure frequency baseline compared with -85%, -71%, and -56% at 3, 6, and 12 months, respectively, using the ECoG seizure frequency baseline. CONCLUSION Chronic ECoG may provide a more accurate estimate of seizure frequency and provide additional insight into the true efficacy of the RNS system.

Back Pain and Spinal Cysticercosis

Dear Editor, Neurocysticercosis is a common parasitic disease of the CNS that is caused by a pork tapeworm (Taenia solium). However, involvement with the spine is uncommon. This report highlights spinal cysticercosis as a cause of low back pain, which is of special interest due to its rare etiology, reportedly accounting for only 1.2% to 5.8% of all cases of neurocysticercosis. Furthermore, the intraspinal type is even more rare, with only 53 cases reported up to 2010.1 A previously healthy 46-year-old man presented with low back pain radiating to the legs. At the initial neurological examination he was awake and alert, with normal cognitive function. There was no cranial nerve impairment or weakness in the upper extremities. He reported subjective pain in the lower extremities, especially in the dorsal-to-lateral aspect of the thighs, calves, and feet bilaterally. However, there was no apparent sensory impairment in any modality, including position sense. His muscle bulk was also normal. There was trivial weakness of left planter flexion and dorsiflexion. Coordination was intact, and deep tendon reflexes were symmetric and within normal limits, with no pathological reflexes suggestive of a long tract sign. He complained of mild ischuria. There was no meningeal sign of neck stiffness. His gait was guarded secondary to the lower extremity pain probably associated with lumbago. Based on the neurological examination, bilateral S1 radiculopathy was suspected, with greater severity on the left. Given his age and presentation, degenerative joint disease was the most likely etiology. However, the initial MRI and CT myelogram of the lumbar spine obtained in 2012 demonstrated a cystic lesion (Fig. 1). The patient underwent laminectomy at the L4–5 and L5–S1 levels. Opening of the dura revealed exudative inflammatory material with cysts. Several cysts were observed enveloped by nerve roots, each of which was carefully dissected microscopically and sent for pathology analysis. The nerve roots were inflamed and difficult to dissect off completely. The procedure was carried out with intraoperative neuromonitoring, which revealed normal motor responses throughout the procedure. No surgical complication was identified. The pathological specimen showed typical findings of neurocysticercosis (Fig. 2). He subsequently presented 4 years later with management noncompliance and worsening bilateral radicular-type pain in both legs in the L5–S1 distribution. A neurological examination revealed no significant weakness in the lower extremities and an intact gait. The patient’s most recent MRI and CT myelogram obtained in 2016 revealed recurrent cysts that had increased in both size and number (Fig. 3). Medical treatment with albendazole was initiated. At the time of writing the patient was reluctant to receive any further surgical intervention, and so was receiving on medical management. Clinically, his lower extremity pain and lumbago had been slowly subsiding since the initiation of albendazole. Spinal cysticercosis is rare, but it should be suspected in patients from endemic regions who complain of backache with radicular pain. The present case of cysticercosis in the lumbar spine is uncommon because cysticercosis is usually found in the thoracic cord. Furthermore, even when a cyst has previously been resected, it is important to consider the risk of Pauline Joy F Santos Shuichi Suzuki Sumeet Vadera

Language recovery after epilepsy surgery of the Broca's area

Epilepsy surgery is indicated in select patients with drug-resistant focal epilepsy. Seizure freedom or significant reduction of seizure burden without risking new neurological deficits is the expected goal of epilepsy surgery. Typically, when the seizure onset zone overlaps with eloquent cortex, patients are excluded from surgery. We present a patient with drug-resistant frontal lobe epilepsy who underwent successful surgery with resection of Brocas area, primarily involving the pars triangularis (BA 45). We report transient expressive aphasia followed by recovery of speech. This case provides new insights into adult neuroplasticity of the language network.

Hippocampal CA1 gamma power predicts the precision of spatial memory judgments

Significance Spatial memory is critical to every facet of our lives. The hippocampus is known to play a prominent role in the formation and retrieval of spatial memories; however, the exact mechanisms remain elusive. Using electrophysiology recordings from presurgical epilepsy patients implanted with depth electrodes, we measured high-frequency neural activity from the CA1 region of the hippocampus and the dorsolateral prefrontal cortex. We found associations between increased high-frequency activity and the precision of spatial memory retrieval. These data suggest that local processing within the CA1 subfield and the dorsolateral prefrontal cortex underlie the quality of retrieved spatial memories. The hippocampus plays a critical role in spatial memory. However, the exact neural mechanisms underlying high-fidelity spatial memory representations are unknown. We report findings from presurgical epilepsy patients with bilateral hippocampal depth electrodes performing an object-location memory task that provided a broad range of spatial memory precision. During encoding, patients were shown a series of objects along the circumference of an invisible circle. At test, the same objects were shown at the top of the circle (0°), and patients used a dial to move the object to its location shown during encoding. Angular error between the correct location and the indicated location was recorded as a continuous measure of performance. By registering pre- and postimplantation MRI scans, we were able to localize the electrodes to specific hippocampal subfields. We found a correlation between increased gamma power, thought to reflect local excitatory activity, and the precision of spatial memory retrieval in hippocampal CA1 electrodes. Additionally, we found a similar relationship between gamma power and memory precision in the dorsolateral prefrontal cortex and a directional relationship between activity in this region and in the CA1, suggesting that the dorsolateral prefrontal cortex is involved in postretrieval processing. These results indicate that local processing in hippocampal CA1 and dorsolateral prefrontal cortex supports high-fidelity spatial memory representations.