Ultrasound-Guided Posterolateral Approach for Midline Calcified Thoracic Disc Herniation

Tan, Lee A.,Lopes, Demetrius K.,Fontes, Ricardo B.V. The Korean Neurosurgical Society 2014 Journal of Korean neurosurgical society Vol.55 No.6

Objective : Symptomatic thoracic disc herniation often requires prompt surgical treatment to prevent neurological deterioration and permanent deficits. Anterior approaches offer direct visualization and access to the herniated disc and anterior dura but require access surgeons and are often associated with considerable postoperative pain and pulmonary complications. A disadvantage with using posterior approaches in the setting of central calcified thoracic disc herniation however, has been the limited visualization of anterior dura and difficulty to accurately assess the extent of decompression. Methods : We report our experience with intraoperative ultrasound (US) guidance during a modified posterior transpedicular approach for removal of a central calcified thoracic disc herniation with a review of pertinent literature. Results : The herniated thoracic disc was successfully removed with posterior approach with the aid of intraoperative US. The patient had significant neurological improvement at three months follow-up. Conclusion : Intraoperative ultrasound is a simple yet valuable tool for real-time imaging during transpedicular thoracic discectomy. Visualization provided by intraoperative US increases the safety profile of posterior approaches and may make thoracotomy unnecessary in a selected group of patients, especially when a patient has existing pulmonary disease or is otherwise not medically fit for the transthoracic approach.

Biomechanical Analysis of 3-Level Anterior Cervical Discectomy and Fusion Under Physiologic Loads Using a Finite Element Model

Lee A. Tan,Narayan Yoganandan,Hoon Choi,Yuvaraj Purushothaman,Davidson Jebaseelan,Aju Bosco 대한척추신경외과학회 2022 Neurospine Vol.19 No.2

Objective: Pseudarthrosis and adjacent segment degeneration (ASD) are 2 common complications after multilevel anterior cervical discectomy and fusion (ACDF). We aim to identify the potential biomechanical factors contributing to pseudarthrosis and ASD following 3-level ACDF using a cervical spine finite element model (FEM). Methods: A validated cervical spine FEM from C2 to C7 was used to study the biomechanical factors in cervical spine intervention. The FEM model was used to simulate a 3-level ACDF with intervertebral spacers and anterior cervical plating with screw fixation from C4 to C7. The model was then constrained at the inferior nodes of the T1 vertebra, and physiological loads were applied at the top vertebra. The pure moment load of 2 Nm was applied in flexion, extension, and lateral bending. A follower axial force of 75 N was applied to reproduce the weight of the cranium and muscle force, was applied using standard procedures. The motion-controlled hybrid protocol was utilized to comprehend the adjustments in the spinal biomechanics. Results: Our cervical spine FEM demonstrated that the cranial adjacent level (C3–4) had significantly more increase in range of motion (ROM) (+90.38%) compared to the caudal adjacent level at C7–T1 (+70.18%) after C4–7 ACDF, indicating that the cranial adjacent level has more compensatory increase in ROM than the caudal adjacent level, potentially predisposing it to earlier ASD. Within the C4–7 ACDF construct, the C6–7 level had the least robust fixation during fixation compared to C4–5 and C5–6, as reflected by the smallest reduction in ROM compared to intact spine (-71.30% vs. -76.36% and -77.05%, respectively), which potentially predisposes the C6–7 level to higher risk of pseudarthrosis. Conclusion: Biomechanical analysis of C4–7 ACDF construct using a validated cervical spine FEM indicated that the C3–4 has more compensatory increase in ROM compared to C7–T1, and C6–7 has the least robust fixation under physiological loads. These findings can help spine surgeons to predicate the areas with higher risks of pseudarthrosis and ASD, and thus developing corresponding strategies to mitigate these risks and provide appropriate preoperative counseling to patients.

Treatment of a Ruptured Vertebrobasilar Fusiform Aneurysm Using Pipeline Embolization Device

Lee A Tan,Roham Moftakhar,Demetrius K. Lopes 대한뇌혈관외과학회 2013 Journal of Cerebrovascular and Endovascular Neuros Vol.15 No.1

Treatment options of ruptured vertebrobasilar fusiform aneurysms (VFA) are limited and often carry significant mortality and morbidity. We report the use of Pipeline Embolization Device (PED) to successfully treat a patient with a ruptured vertebrobasilar fusiform aneurysm (VFA) who presented with subarachnoid hemorrhage (SAH). A 73 year-old man with a history of cardiac stent placement seven days earlier presented with Hunt-Hess II SAH. He was taking aspirin and clopidogrel. Computed tomography angiogram revealed a large vertebrobasilar fusiform aneurysm. Microsurgical treatment options are technically challenging and carry high risk. He underwent endovascular treatment of the ruptured VFA using overlapping PEDs. Five PEDs were placed in a telescoping fashion to reconstruct the affected portions of the left vertebral and basilar arteries. An additional 2-mm blister aneurysm in the right vertebral artery was also discovered during the conventional cerebral angiography and was treated with one additional PED. The patient remained neurologically intact after the procedure. He was continued on aspirin and clopidogrel. Follow-up magnetic resonance imaging at three months demonstrated patency of the stents without any evidence of ischemic change. Follow-up conventional cerebral angiogram at six months demonstrated thrombosis of the VFA and reconstruction of the vertebrobasilar system. The patient remained clinically well. An endovascular approach using PEDs can be a safe and effective treatment option for ruptured VFA in selected cases.

Mutations in SLC26A1 Cause Nephrolithiasis

Gee, H.Y.,Jun, I.,Braun, D.A.,Lawson, J.A.,Halbritter, J.,Shril, S.,Nelson, C.P.,Tan, W.,Stein, D.,Wassner, A.J.,Ferguson, M.A.,Gucev, Z.,Sayer, J.A.,Milosevic, D.,Baum, M.,Tasic, V.,Lee, M.G.,Hildebr University of Chicago Press [etc.] 2016 American journal of human genetics Vol.98 No.6

<P>Nephrolithiasis, a condition in which urinary supersaturation leads to stone formation in the urinary system, affects about 5%-10% of individuals worldwide at some point in their lifetime and results in significant medical costs and morbidity. To date, mutations in more than 30 genes have been described as being associated with nephrolithiasis, and these mutations explain about 15% of kidney stone cases, suggesting that additional nephrolithiasis-associated genes remain to be discovered. To identify additional genes whose mutations are linked to nephrolithiasis, we performed targeted next-generation sequencing of 18 hypothesized candidate genes in 348 unrelated individuals with kidney stones. We detected biallelic mutations in SLC26A1 (solute carrier family 26 member 1) in two unrelated individuals with calcium oxalate kidney stones. We show by immunofluorescence, immunoblotting, and glycosylation analysis that the variant protein mimicking p.Thr185Met has defects in protein folding or trafficking. In addition, by measuring anion exchange activity of SLC26A1, we demonstrate that all the identified mutations in SLC26A1 result in decreased transporter activity. Our data identify SLC26A1 mutations as causing a recessive Mendelian form of nephrolithiasis.</P>

Selection of the Lowest Instrumented Vertebra and Relative Odds Ratio of Distal Adding-on for Lenke Type 1A and 2A Curves in Adolescent Idiopathic Scoliosis: A Systematic Review and Meta-analysis

Che-Wei Liu,Lawrence G. Lenke,Lee A. Tan,Taemin Oh,Kou-Hua Chao,Shi-Ding Lin,Ru-Yu Pan 대한척추신경외과학회 2020 Neurospine Vol.17 No.4

Objective: To examine existing literature and pool the data to determine the relative odds ratio of “adding-on” (AO) based on various reported criteria for lower instrumented vertebra (LIV) selection in Lenke type 1A and 2A curves. Methods: Using electronic databases, studies reporting on AO and LIV selection in Lenke type 1A and 2A curves were identified. Studies were excluded if they failed to meet the following criteria: ≥30 patients, Lenke type 1A or 2A curves, thoracic-only fusions, and inclusion of outcome differences in AO and non-AO groups. Review articles, letters, and case reports were excluded. Results: Six studies were identified reporting on 732 patients with either Lenke type 1A or 2A curves treated with thoracic-only fusions. Five different landmarks were used for LIV selection in these studies including the stable vertebra (SV) -1, end vertebra (EV) +1, neutral vertebra (NV), touched vertebra (TV), and substantially touched vertebra (STV) versus nonsubstantially touched vertebra (nSTV) +1. The pooled odds ratios of AO for choosing LIV at levels above the afore landmarks (i.e., ending the construct “short”) versus at the landmarks were 2.59 (SV-1), 2.43 (EV+1), 3.05 (NV), 3.40 (TV), and 4.52 (STV/nSTV+1), all at 95% confidence interval. Conclusion: Five landmarks shared a similar characteristic in that the incidence of AO was significantly higher if the LIV was proximal to the chosen landmark. In addition, choosing STV/(nSTV+1) as the LIV have the lowest absolute risk of AO and the greatest risk reduction. If additional levels were fused (i.e., LIV distal to the landmark), there was no statistically significant benefit in further reducing the risk of AO. Selection of the optimal LIV is a complex issue and spine surgeons must balance the risk of AO with the need for motion preservation in young patients.

Ventriculoperitoneal Shunt in a Patient with Ruptured Blister Aneurysm Treated with Pipeline Embolization Device

Lee A Tan,Carter S. Gerard,Kiffon M. Keigher,Roham Moftakhar,Demetrius K. Lopes 대한뇌혈관외과학회 2015 Journal of Cerebrovascular and Endovascular Neuros Vol.17 No.1

Cerebral spinal fluid (CSF) diversion is frequently required in patients with aneurysmal subarachnoid hemorrhage who develop subsequent hydrocephalus. Procedures such as external ventricular drain (EVD) and ventriculoperitoneal shunt (VPS) usually carry a very low rate of complications. However, as flow diverting stents such as Pipeline Embolization Device (PED) become more widely available, flow diverters are being used in treatment of some ruptured complex aneurysms. EVD and VPS placement in the setting of dual antiplatelet therapy (DAT) in these patients are associated with a significant risk of intracranial hemorrhage. We describe a management strategy and surgical technique that can minimize hemorrhagic complications associated with VPS in patients on DAT after treatment with flow diverting stents.

To vape or not to vape? Effects of exposure to conflicting news headlines on beliefs about harms and benefits of electronic cigarette use: Results from a randomized controlled experiment

Tan, Andy S.L.,Lee, Chul-joo,Nagler, Rebekah H.,Bigman, Cabral A. Elsevier 2017 Preventive medicine Vol.105 No.-

<P><B>Abstract</B></P> <P>News coverage of novel tobacco products including e-cigarettes has framed the use of these products with both positive and negative slants. Conflicting information may shape public knowledge, perceptions of e-cigarettes, and their harms. The objective of this study is to assess effects of exposure to conflicting news coverage on US adults' beliefs about harms and benefits of e-cigarette use. We conducted a one-way between-subjects randomized controlled experiment in 2016 to compare the effects of viewing either 1) positive, 2) negative, 3) both positive and negative (conflicting) news headlines about the safety of using e-cigarettes, or 4) no-message. Participants were 2056 adults aged 18 and older from an online survey panel. Outcomes were beliefs about harms (3-item scale, α=0.76) and benefits (3-item scale, α=0.82) of using e-cigarettes. Participants who viewed negative headlines reported increased beliefs about harms (B=0.164, p=0.039) and lower beliefs about benefits of e-cigarette use (B=−0.216, p=0.009), compared with those in the positive headlines condition. These differences were replicated in subgroup analyses among never e-cigarette users. In addition, never e-cigarette users who viewed conflicting headlines reported lower beliefs about benefits of e-cigarette use (B=−0.221, p=0.030) than the positive headlines condition. Valence of news coverage about e-cigarettes (positive, negative, or conflicting) could influence people's beliefs about harms and benefits of e-cigarette use.</P> <P><B>Highlights</B></P> <P> <UL> <LI> In an experiment, participants viewed news headlines about e-cigarettes. </LI> <LI> Outcomes were beliefs about harms and benefits of using e-cigarettes. </LI> <LI> Negative headlines increased beliefs about harms and reduced beliefs about benefits. </LI> <LI> Conflicting headlines reduced beliefs about benefits of e-cigarette use among never users. </LI> <LI> Valence of news coverage about e-cigarettes could influence people's beliefs about e-cigarette use. </LI> </UL> </P>

A missense variant in NCF1 is associated with susceptibility to multiple autoimmune diseases

Zhao, Jian,Ma, Jianyang,Deng, Yun,Kelly, Jennifer A,Kim, Kwangwoo,Bang, So-Young,Lee, Hye-Soon,Li, Quan-Zhen,Wakeland, Edward K,Qiu, Rong,Liu, Mengru,Guo, Jianping,Li, Zhanguo,Tan, Wenfeng,Rasmussen, Nature Pub. Co 2017 Nature genetics Vol.49 No.3

<P>Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease with a strong genetic component characterized by autoantibody production and a type 1 interferon signatures. Here we report a missense variant (g.74779296G>A; p.Arg90His) in NCF1, encoding the p47phox subunit of the phagocyte NADPH oxidase (NOX2), as the putative underlying causal variant that drives a strong SLE-associated signal detected by the lmmunochip in the GTF2IRD1-GTF2I region at 7q11.23 with a complex genomic structure. We show that the p.Arg90His substitution, which is reported to cause reduced reactive oxygen species (ROS) production(2), predisposes to SLE (odds ratio (OR) = 3.47 in Asians (P-meta = 3.1 x 10(-104)), OR = 2.61 in European Americans, OR = 2.02 in African Americans) and other autoimmune diseases, including primary Sjogren's syndrome (OR = 2.45 in Chinese, OR = 2.35 in European Americans) and rheumatoid arthritis (OR = 1.65 in Koreans). Additionally, decreased and increased copy numbers of NCF1 predispose to and protect against SLE, respectively. Our data highlight the pathogenic role of reduced NOX2-derived ROS levels in autoimmune diseases.</P>

Symptomatic Cerebral Air Embolism During Stent-assisted Coiling of an Unruptured Middle Cerebral Artery Aneurysm: Intraoperative Diagnosis and Management of a Rare Complication

Lee A Tan,Kiffon M. Keigher,Demetrius K. Lopes 대한뇌혈관외과학회 2014 Journal of Cerebrovascular and Endovascular Neuros Vol.16 No.2

Symptomatic Cerebral Air Embolism During Stent-assistedCoiling of an Unruptured Middle Cerebral Artery Aneurysm:Intraoperative Diagnosis and Management of a RareComplication

Cervical Angina

Lee A. Tan 대한척추신경외과학회 2020 Neurospine Vol.17 No.4