Tianyi Niu

Molecular and cellular development of spinal cord locomotor circuitry.

The spinal cord of vertebrate animals is comprised of intrinsic circuits that are capable of sensing the environment and generating complex motor behaviors. There are two major perspectives for understanding the biology of this complicated structure. The first approaches the spinal cord from the point of view of function and is based on classic and ongoing research in electrophysiology, adult behavior, and spinal cord injury. The second view considers the spinal cord from a developmental perspective and is founded mostly on gene expression and gain-of-function and loss-of-function genetic experiments. Together these studies have uncovered functional classes of neurons and their lineage relationships. In this review, we summarize our knowledge of developmental classes, with an eye toward understanding the functional roles of each group.

Multimodal endovascular therapy of traumatic and spontaneous carotid cavernous fistula using coils, n-BCA, Onyx and stent graft

Background and purpose Carotid cavernous fistula (CCF) can be classified as either direct or indirect according to the arterial feeder source. The current standard treatment for CCF is endovascular embolization. In this case series, 21 CCF (direct and indirect) embolization procedures were treated with multimodal endovascular therapy to explore safety, technique and clinical efficacy. Method and patients The neurointerventional database was reviewed for all cases of CCF. Demographic information, indications for the procedure, presenting symptoms, endovascular therapy types, complications and procedure angiographic and clinical efficacy were collected. Results 21 CCF embolization procedures were performed using multimodal therapy on 15 patients (eight females and seven males) with a mean age of 56.4±22.4 years (15–90 years), with 60% traumatic CCF and 40% spontaneous CCF presenting mainly with typical visual symptoms. 10 patients were treated in one session, four patients underwent two sessions and one required three sessions of endovascular therapy. Complete fistula occlusion was achieved in 10/15 patients (73.3%) in one session and in 14/15 (93.3%) patients after two or more sessions. One patients symptoms (case No 15) improved dramatically after the second session despite incomplete obliteration of the CCF. No periprocedural complications were reported. Long term follow-up showed one recurrence of the CCF with a mean follow-up time of 201±17.2 months (range 1–56 months). Patient No 6 was lost to follow-up. Conclusion Multimodal endovascular embolization of CCF appears to be safe with a high success rate of complete obliteration. This case series demonstrates complete occlusion in 73.3% of the patients after one session and in 93.3% after the second session.

The use of a covered stent graft for obliteration of high-flow carotid cavernous fistula presenting with life-threatening epistaxis

Background We present a rare complication of trans-sphenoidal adenectomy (TSA) for pituitary macroadenoma: carotid cavernous fistula (CCF) that was treated with endovascular therapy. The incidence of internal carotid artery (ICA) injury following TSA is 1% and may spontaneously heal by packing and rarely manifest as symptomatic CCF/aneurysm. Treatment of post-TSA CCF may be challenging due to the breach of nasal floor and may be prone to recurrence. Presentation/intervention Uncontrolled intra-operative bleeding during a TSA led to an emergent angiogram to show slow-flow left CCF. Due to clinical deterioration with nasal bleeding, angiography was repeated after 4 h; the fistula had transformed into high flow with significant increase in size, and was therefore embolized using stent-assisted coiling. The fistula recanalized in a month with massive epistaxis and was re-treated using a covered stent graft. Conclusion This case represents several unique learning points: (1) CCF as a complication of TSA due to close anatomical proximity; (2) the role of endovascular management post-TSA complication; (3) stent-assisted coil embolization of high-flow fistula with moderate ICA laceration; (4) recanalization of CCF causing massive epistaxis; (5) rare use of covered stent graft stent in distal intracranial circulation maintaining integrity and patency of ICA; (6) long-term results after covered stent graft with no in-stent restenosis.

Limbic Neuromodulation: Implications for Addiction, Posttraumatic Stress Disorder, and Memory

Deep brain stimulation, a technique whereby electrodes are implanted into specific brain regions to modulate their activity, has been mainly used to treat movement disorders. More recently this technique has been proposed for the treatment of drug addiction, posttraumatic stress disorder (PTSD), and dementia. The nucleus accumbens, amygdala, and hippocampus, central nuclei within the limbic system, have been studied as potential targets for neuromodulation for the treatment of drug addiction, PTSD, and dementia, respectively. As the scope of neuromodulation grows to include disorders of mood and thought, new ethical and philosophic challenges that require multidisciplinary discussion and cooperation are emerging.

Rare vascular complication of percutaneous balloon compression of trigeminal neuralgia treated endovascularly

Trigeminal neuralgia is commonly treated with percutaneous balloon compression due to the high success rate, technical simplicity and cost efficiency.1–3 The procedure carries certain risks, most notably dysesthesias and masseter muscle weakness.4 5 However, more severe complications are rare. In this report, the case of a rare complication of percutaneous balloon compression for trigeminal neuralgia is presented, resulting in a carotid cavernous fistula treated via an endovascular approach.

Aquaporin-1 Expression in Herniated Human Lumbar Intervertebral Discs

Study Design: Case series. Objective: Intervertebral disc (IVD) degeneration is the cause of spondylosis. The pathogenesis is poorly understood, but disc dehydration often plays a role. In this study, we aim to identify and quantify aquaporin-1 (AQP1) in ex vivo human degenerated IVDs obtained intraoperatively and to investigate the relationship between AQP1 levels and magnetic resonance imaging (MRI) T2 intensity of the disc. Methods: Ex vivo samples of nucleus pulposus (NP) tissue from lumbar IVDs were obtained from 18 consecutive patients who underwent surgery for disc herniation at L4/5 and L5/S1 level. Immunohistochemistry was performed to determine the presence of AQP1 expression, and this was quantified by Western blot analysis. AQP1 expression was compared to preoperative IVD signal intensity on T2-weighted MRI. Results: NP tissue was obtained from 18 patients (9 for L4/5 level and 9 for L5/S1 level). AQP1 expression was detected in all samples by Western blot and immunohistochemistry. AQP1 expression had a linear correlation with the preoperative IVD signal intensity on T2-weighted MRI at L4/5 level (R 2 = 0.90) and at L5/S1 level (R 2 = 0.92). AQP1 expression was 52.2 ± 59.0 at L5/S1 level and 15.9 ± 20.6 at L4/5 (P = .10). Conclusions: Our results show that AQP1 can be detected in IVD obtained from live human subjects. Increased AQP1 expression is associated with greater disc hydration as measured by signal intensity on T2-weighted MRI. AQP1 may have a role in the dehydration associated with disc degeneration.

A review of the diagnosis and management of vertebral basilar (posterior) circulation disease

We have reviewed the English literature published in the last 70 years on Diseases of the Vertebral Basilar Circulation, or Posterior Circulation Disease (PCD). We have found that errors have been made in the conduct and interpretation of these studies that have led to incorrect approaches to the management of PCD. Because of the difficulty in evaluating the PC, the management of PCD has been incorrectly applied from anterior circulation disease (ACD) experience to PCD. PCD is a common form of stroke affecting 20-40% patients with stroke. Yet, the evidence is strong that the Anterior Circulation (AC) and Posterior Circulations (PC) differ in their pathology, in their clinical presentations, in the rapidity of development of symptoms, in optimal imaging methods, and in available treatments. There appears to be two categories of patients who present with PCD. The first, acute basilar artery occlusion has a more rapid onset. The diagnosis must be made quickly and if imaging proves a diagnosis of Basilar Artery Occlusion (BAO), the treatment of choice is Interventional removal of the basilar artery thrombosis or embolus. The second category of PCD and the most commonly seen PCD disease process presents with non-specific symptoms and early warnings of PCD that now can be related to ischemic events in the entire PC vessels. These warning symptoms and signs occur much earlier than those in the AC. IA angiography is still the gold standard of diagnosis and is superior in definition to MR and CT angiography which are commonly used as a convenient screening imaging tool to evaluate PCD but are both inferior to IA angiography in definition for lesions below 3-4 mm. In at least two reported studies 7T MR angiography appears superior to other imaging modalities and will become the gold standard of imaging of PCD in the future. Medical treatments applied to the ACD have not been proven of value in specific forms of PCD. Interventional therapy was promising but of unproven value in Randomized Controlled Trials (RCT) except for the treatment of Basilar Artery Occlusion (BAO). Surgical revascularization has been proved to be highly successful in patients, who are refractory to medical therapy. These studies have been ignored by the scientific community basically because of an incorrect interpretation of the flawed EC-IC Bypass Trial in 1985 as applying to all stroke patients. Moreover, the EC-IC Bypass Study did not include PCD patients in their study population, but the study results were extrapolated to patients with PCD without any scientific basis. This experience led clinicians to an incorrect bias that surgical treatments are of no value in PCD. Thus, incorrectly, surgical treatments of PCD have not been considered among the therapeutic possibilities for PCD. QMRA is a new quantitative MR technique that measures specific blood flow in extra and intracranial vessels. QMRA has been used to select those patients who may benefit from medical, or interventional, or surgical treatment for PCD based on flow determinations with a high success rate. QMRA accurately predicts the flows in many large and small vessels in the PC and AC and clearly indicates that both circulations are intimately related. From medical and surgical studies, the longer one waits for surgical treatment the higher the risk of a poor outcome results. This observation becomes obvious when the rapidity of development of PCD is compared with ACD. Recent advances in endovascular therapy in the treatment of acute basilar thrombosis is a clear sign that early diagnosis and treatment of PCD will reduce the morbidity and mortality of these diseases. In this review it is evident that there are multiple medical and surgical treatments for PCD depending upon the location of the lesion(s) and the collateral circulation demonstrated. It is clear that the AC and PC have significant differences. With the exception of the large population studies from Oxford England, the reported studies on the management of PCD in the literature represent small selected subsets of the universe of PC diseases, the information from which is not generalizable to the universe of PCD patients. At this point in the history of PCD, there are not large enough databases of similar patients to provide a basis for valid randomized studies, with the exception of the surgical studies. Thus, a high index of suspicion of the early warning symptoms of PCD should lead to a rapid individual clinical assessment of patients selecting those with PCD. Medical, interventional, and/or surgical treatments should be chosen based on knowledge presented in this review. Recording the results in a national Registry on a continuing basis will provide the data that may help advance the management of PCD based on larger data bases of well documented patient information to guide the selection of future therapies for PCD treatments. It is also clear that the management of patients within the complex of diseases that comprise PCD should be performed in centers with expertise in the imaging, medical, interventional and surgical approaches to diseases of the PCD.

Neurenteric cyst of the conus medullaris

Background: Neurenteric cysts (NECs) are rare developmental malformations of the central nervous system (CNS) which originate as benign congenital lesions. They originate from developmental foregut precursors, and are presumed to be the result of abnormal partitioning of the embryonic notochord plate. Such NECs predominantly arise in the cervical region in patients around 6 years of age or in their twenties or thirties. Notably, NECs of the conus medullaris are exceedingly rare, especially in patients of advanced age. Case Description: A 70-year-old male presented with bilateral upper thigh and leg pain of over 20 years duration. His pain worsened over the past 3 years, and he sought surgical management. Although his neurological exam was normal, the lumbar magnetic resonance imaging revealed an intradural, nonenhancing, thin-walled, cystic lesion at L1/conus medullaris. The lesion was successfully resected without any adverse sequelae. Conclusions: NECs are rare congenital legions that involve the spine. Here, an L1 intradural extramedullay neuroenteric cyst of the conus medullaris was resected without complications.

Survival Outcomes After Intracranial Hemorrhage in Liver Disease

BACKGROUND Survival outcomes for patients with liver disease who suffer an intracranial hemorrhage (ICH) have not been thoroughly investigated. OBJECTIVE To understand survival outcomes for 3 groups: (1) patients with an admission diagnosis of liver disease (end-stage liver disease [ESLD] or non-ESLD) who developed an ICH in the hospital, (2) patients with ESLD who undergo either operative vs nonoperative management, and (3) patients with ESLD on the liver transplant waitlist who developed an ICH in the hospital. METHODS We retrospectively reviewed hospital charts from March 2006 through February 2017 of patients with liver disease and an ICH evaluated by the neurosurgery service at a single academic medical center. The primary outcome was survival. RESULTS We included a total of 53 patients in this study. The overall survival for patients with an admission diagnosis of liver disease who developed an ICH (n = 29, 55%) in the hospital was 22%. Of those patients with an admission diagnosis of liver disease, 27 patients also had ESLD. Kaplan-Meier analysis found no significant difference in survival for ESLD patients (n = 33, 62%) according to operative status. There were 11 ESLD patients on the liver transplant waitlist. The overall survival for patients with ESLD on the liver transplant waitlist who suffered an in-hospital ICH (n = 7, 13%) was 14%. CONCLUSION ICH in the setting of liver disease carries a grave prognosis. Also, a survival advantage for surgical hematoma evacuation in ESLD patients is not clear.

Surgical nuances of partial sacrectomy for chordoma

Background: Sacral chordomas are rare, slow growing, locally aggressive tumors. Unfortunately, aggressive surgical resection is often associated with increased neurological morbidity. Methods: This technical note focuses on the utilization of partial sacrectomy for the resection of complex spinal chordomas. Results: The case presented documents the potential range of postoperative morbidity seen in patients undergoing partial sacrectomy for chordomas. Despite iatrogenic morbidity and tumor recurrence, with the cooperation of medical and surgical spine specialists, majority of patients can achieve good long-term outcomes. Conclusions: Sacral chordomas are rare lesions and pose a therapeutic challenge for spinal surgeons and oncologists. En-bloc surgical resection (e.g., partial sacrectomy) is the treatment of choice for these lesions, and the cooperation between subspecialists can lead to good neurologic outcomes, particularly if gross total resection is achieved.