Lee A Tan

• MD
• Professor (Assistant) at University of California, San Francisco

Cervical spine deformities can have a significant negative impact on the quality of life by causing pain, myelopathy, radiculopathy, sensorimotor deficits, as well as inability to maintain horizontal gaze in severe cases. Many different surgical options exist for operative management of cervical spine deformities. However, selecting the correct app...

A sound operative plan based on solid understanding of the pathology and biomechanics is the most important part of cervical deformity correction. Many different surgical options exist for operative management of cervical spine deformities. However, selecting the correct approach that ensures the optimal clinical outcome can be challenging and ofte...

Purpose: Correction of rigid cervical deformities often requires osteotomies to realign the spine. Cervical pedicle subtraction osteotomy can be technically challenging due to the presence of cervical nerve roots and usually can only be performed at C7 or T1 due to the presence of vertebral arteries. In contrast, anterior cervical osteotomy can be...

OBJECT The cervical interfacet spacer (CIS) is a relatively new technology that can increase foraminal height and area by facet distraction. These offer the potential to provide indirect neuroforaminal decompression while simultaneously enhancing fusion potential due to the relatively large osteoconductive surface area and compressive forces exerte...

Object Minimally invasive surgery (MIS) has been increasingly used for the treatment of various intradural spinal pathologies in recent years. Although MIS techniques allow for successful treatment of intradural pathology, primary dural closure in MIS can be technically challenging due to a limited surgical corridor through the tubular retractor sy...

Introduction: In a multilevel cervical laminoplasty operation for patients with cervical spondylotic myelopathy (CSM), a partial or complete C3 laminectomy may be performed at the upper level instead of a C3 plated laminoplasty. It is unknown whether C3 technique above the laminoplasty affects loss of cervical lordosis or range of motion. Methods...

OBJECTIVE Postoperative C5 palsy (C5P) is a known complication in cervical spine surgery. However, its exact pathophysiology is unclear. The authors aimed to provide a review of the current understanding of C5P by performing a comprehensive, systematic review of the existing literature and conducting a critical appraisal of existing evidence to det...

Study design: Operative video and supplemental manuscript. Objective: To present a novel step-by-step approach to performing a lumbar pedicle subtraction osteotomy (PSO) using laterally based satellite rods. Summary of background data: Multi-rod constructs have demonstrated paramount for decreasing rates of pseudarthrosis after PSOs. Multi-rod...

Objective: Vertebral osteomyelitis is a rare complication of coccidioidomycosis infection. Surgical intervention is indicated when there is failure of medical management or presence of neurological deficit, epidural abscess, or spinal instability. The relationship between timing of surgical intervention and recovery of neurological function has no...

OBJECTIVE Spinal meningiomas pose unique challenges based on the location of their dural attachment. However, there is a paucity of literature investigating the role of dural attachment location on outcomes after posterior-based approach for spinal meningioma resection. The aim of this study was to investigate any differences in outcomes between du...

A failed transforaminal lumbar interbody fusion (TLIF) may require a salvage surgery in patients who develop new or recurrent symptoms. The causes of symptoms after a previous TLIF include adjacent segment stenosis, instability after previous decompressive surgery, pseudarthrosis, and cage subsidence. There are various options to approach the remov...

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OBJECTIVE Ankylosing spondylitis, the most common spondyloarthritis, fuses individual spinal vertebrae into long segments. The unique biomechanics of the ankylosed spine places patients at unusually high risk for unstable fractures secondary to low-impact mechanisms. These injuries are unique within the spine trauma population and necessitate thoug...

BACKGROUND Posterior cervical decompression and fusion (PCF) is a common procedure used to treat various cervical spine pathologies, but the 90-d outcomes following PCF surgery continue to be incompletely defined. OBJECTIVE To identify risk factors associated with 90-d readmission and reoperation following PCF surgery. METHODS Adults undergoing P...

BACKGROUND Spontaneous intracranial hypotension (SIH) is usually caused by a spinal cerebrospinal fluid (CSF) leak. CSF-venous fistula is an underdiagnosed cause of spinal CSF leak, as it is challenging to identify on myelography. OBJECTIVE To review existing literature to summarize common presentations, diagnostic imaging modalities, and current...

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...

Pseudarthrosis is a well-recognized complication following multi-level ACDF. We aim to characterize the fusion order and level-specific rates of arthrodesis across four time points following 3-level ACDF. Patients who underwent 3-level ACDF by three UCSF spine surgeons from August 2012 to December 2019 were identified. Fusion status at each level w...

OBJECTIVE Potential advantages of using expandable versus static cages during transforaminal lumbar interbody fusion (TLIF) are not fully established. The authors aimed to compare the long-term radiographic outcomes of expandable versus static TLIF cages. METHODS A retrospective review of 1- and 2-level TLIFs over a 10-year period with expandable...

Background: Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is a surgical technique frequently used to treat symptomatic lumbar spondylolisthesis. We aim to investigate the safety and efficacy of using a biplanar expandable cage in the treatment of symptomatic lumbar spondylolisthesis using a MIS TLIF approach. Methods: A re...

Introduction: Atypical teratoid/rhabdoid tumor (AT/RT) is a rare tumor of the central nervous system, especially when involving the spinal column or spinal cord. Case presentation: We present a case of a 5-year-old girl with progressive bilateral lower extremity pain found to have a discrete nodular lesion of the conus with mild heterogeneous en...

BACKGROUND CONTEXT Anterior cervical discectomy and fusion (ACDF) is a common procedure for the treatment of cervical radiculopathy and myelopathy. PURPOSE Multilevel ACDFs are often used to address multi-level cervical stenosis. The purpose of this study is to provide a chronological, level-specific characterization of fusion order and fusion rat...

Renal cell carcinoma (RCC) commonly metastasizes to the lung, liver, bones, and brain; however, cutaneous metastases remain rare with few reported cases. Since RCCs have the propensity to metastasize to highly vascular areas, the scalp and skin of the head and neck region are likely locations for cutaneous metastases. We report a rare case of a lar...

Background: The utilization of the S2 Alar-Iliac (S2AI) screw provides an optimal method of spinopelvic fixation. The free-hand placement of these screws obviates the use of intra-operative fluoroscopy and relies heavily on sacropelvic anatomy; variations of this anatomy could alter the ideal screw trajectory. The S2AI corridor is near several neu...

Background: For laminectomy and posterior spinal fusion (LPSF) surgery for cervical spondylotic myelopathy (CSM), the evidence is unclear as to whether fusions should cross the cervicothoracic junction (CTJ). Objective: To compare LPSF outcomes between those with and without lower instrumented vertebrae (LIV) crossing the CTJ. Methods: A conse...

Background: Prescription opioid use and opioid-related deaths have become an epidemic in the United States, leading to devastating economic and health ramifications. Opioids are the most commonly prescribed drug class to treat low back pain, despite the limited body of evidence supporting their efficacy. Furthermore, preoperative opioid use prior...

The Cervical Spine Research Society (CSRS) is dedicated to advancing the care of patients with cervical spine pathology. The authors present here highlights of the 2019 CSRS-Asia Pacific Traveling Fellowship.

Surgical site infections (SSI) following cervical spine surgery can lead to significant patient morbidity and costs. Prevention of SSIs is multifactorial and can be divided in to preoperative patient optimization and intraoperative surgical factors. We performed a literature review to identify methods that can be used to prevent SSI development spe...

Cervical spine pathology is becoming increasingly prevalent with an aging world population and is associated with significant morbidity, affecting all areas of the world. This review was undertaken to provide a global perspective on cervical spine pathology, including epidemiology, burden of disease, access to care, and plan of care in both develop...

Posterior cervical spine fixation is a key component in achieving spinal arthrodesis for treating various cervical spine pathologies including neoplastic, inflammatory, traumatic and degenerative diseases. Historically, various wiring techniques had played major roles in posterior cervical spine fixation. Today, posterior cervical screw fixation is...

Cervical radiculopathy is a common spinal condition associated with pain, sensory disturbances, and motor weakness. Symptoms often can be attributable to either disc herniation and/or bony foraminal stenosis due to uncinate hypertrophy. Posterior cervical foraminotomy and conventional anterior cervical discectomy and fusion (ACDF) represent the mai...

Posterior atlantoaxial fusion is an important surgical technique frequently used to treat various pathologies involving the cervical 1-2 joint. Since the beginning of the 20th century, various fusion techniques have been developed with improved safety profile, higher fusion rates, and superior clinical outcome. Despite the advancement of technology...

Posterior cervical osteotomies are powerful techniques for the correction of rigid cervical deformity. These include a variety of subtypes including partial facet joint resection, complete facet joint resection, opening wedge osteotomy (OWO), and closing wedge osteotomy (CWO). The partial facet joint resection provides limited lordosis but can be a...

Posterior cervical decompression and fusion (PCF) is a common surgical technique used to treat various cervical spine pathologies. However, there are various complications associated with PCF that can negatively impact patient outcome. We performed a comprehensive literature review to identify the most common complications following PCF using PubMe...

Rigid deformities of the cervical spine can be associated with significant pain, disability, and impaired quality of life. Historical treatments generally utilized posterior approaches including the opening wedge osteotomy and pedicle subtraction osteotomy (PSO). Translation can occur during osteoclasis of the opening wedge osteotomy, making it inh...

Study designRetrospective outcome analysis of a prospectively collected single-surgeon casesObjectives Identify risk factors for complications in adult surgical spine deformity patients, develop a surgeon-specific risk stratification model, and predict the likelihood of 6-week postoperative complications based on prospectively collected preoperativ...

Background: Anterior cervical discectomy and fusion (ACDF) is being increasingly offered on an outpatient basis. However, the safety profile of outpatient ACDF remains poorly defined. Objective: To review the medical literature on the safety of outpatient ACDF. Methods: We systematically reviewed the literature for articles published before Ap...

Study Design Literature review. Objectives Surgical site infection (SSI) following spine surgery leads to significant patient morbidity, mortality, and increased health care costs. The purpose of this article is to identify risk factors and strategies to prevent SSIs following spine surgery, with particular focus on avoiding infections in posterio...

Lumbar spinal stenosis (LSS) is characterized by narrowing of the central canal, lateral recesses, or foramina leading to compression of neural tissue. The clinical syndrome associated with LSS is usually neurogenic claudication, which often presents as lower back and extremity pain, numbness, and tingling upon ambulation. Autonomic dysfunction is...

C1 stenosis is often an easily missed cause for cervical myelopathy. The vast majority of cervical myelopathy occurs in the subaxial cervical spine. The cervical canal is generally largest at C1/2, explaining the relatively rare incidence of neurological deficits in patients with odontoid fractures. However, some subjects have anatomical anomalies...

Objective: This retrospective cohort study seeks to identify risk factors associated with complications following posterior cervical laminectomy and fusion (PCLF) surgery. Methods: Adults undergoing PCLF from 2012 through 2018 at a single center were identified. Demographic and radiographic data, surgical characteristics, and complication rates...

Due to the highly mobile nature of the cervical spine, and the fact that most magnetic resonance imagings (MRIs) and computed tomography scans are obtained only in one single position, dynamic cord compression can be an elusive diagnosis that is often missed and not well-understood. In this context, dynamic MRI (dMRI) has been utilized to improve t...

INTRODUCTION For patients undergoing posterior cervical laminectomy and fusion (PCLF) with an upper thoracic lower instrumented vertebra (LIV), the evidence is unclear as to whether C2 vs C3 is the ideal upper instrumented vertebra (UIV). This study analyzes short-term postoperative outcomes for PCLF comparing cervicothoracic constructs with UIV at...

INTRODUCTION Anterior cervical discectomy and fusion (ACDF) is one of the most prevalent surgical procedures and is used to treat several cervical spinal pathologies, including herniated discs, degenerative disc disease, and spondylosis. With the increasing prevalence of ACDF procedures, this procedure has become an excellent target for clinical op...

The diagnosis of cervical spondylotic myelopathy (CSM) is made based on clinical signs and symptoms, and then confirmed with magnetic resonance imaging (MRI) or CT myelogram. Due to the highly mobile nature of the cervical spine, and the fact that most MRIs and CTs are obtained only in one single position, dynamic cord compression can be an elusive...

Purpose: To validate with a prospective study a decision-supporting coding system for the surgical approach for multi-level degenerative cervical myelopathy (mDCM). Methods: Ten cases were presented on an internet platform, including clinical and imaging data. A single approach (G1), a choice between two (G2), or three approaches (G3) were optio...

Multiple sclerosis (MS) and cervical stenosis (CS) are two unique pathologies that can present with overlapping symptoms. In patients with concurrent MS and CS, the exact cause for worsening of symptoms is often difficult to decipher. In this study, we aimed to review the medical literature on the benefits of surgical decompression surgery in patie...

Intramedullary spinal epidermoid cysts are rare tumors and only account for 1% of all spinal tumors in adults. Epidermoid cysts can develop from ectodermal tissue that was inappropriately positioned in the primitive neural tube during closure; acquired forms exist for epidermoid cysts as they can emerge in an iatrogenic manner following repeated lu...

Background: Several cervical laminectomy techniques have been described. One commonly used method involves making bilateral trough laminotomies using either a Kerrison rongeur or a high speed burr, and then removing the lamina en-bloc. Alternatively, some surgeons prefer to thin the lamina with the burr, and then remove the lamina in a piecemeal fa...

Cervical laminoplasty is an effective and well-established motion preserving treatment for cervical myelopathy and myeloradiculopathy. Many different laminoplasty methods have been developed over the last 35 years since the original technique, including open-door laminoplasty, French-door laminoplasty, dome-shaped laminoplasty, and many other varia...

OBJECTIVE To demonstrate that a more ventral starting point for thoracic pedicle screw insertion, produced by aggressively removing the dorsal transverse process bone down to the superior articular facet (SAF), results in a larger margin for error and more medial screw angulation compared to the traditional dorsal starting point (DSP). The margin f...

Tranexamic acid (TXA) is a commonly used antifibrinolytic agent for perioperative blood conservation in several surgical specialties. Although historically administered intravenously, such systemic administration may be accompanied by severe side effects. Thus, the topical usage of TXA has been established in several fields but remains poorly evalu...

Background: Vocal cord dysfunction resulting from recurrent laryngeal nerve palsy (RLNP) is a known complication following anterior cervical discectomy and fusion. RLNP occurs typically secondary to neurapraxia caused by intraoperative compression or traction on the nerve and less commonly from direct nerve injury intraoperatively in the setting of...

Determining the responsible level of cervical radiculopathy can be difficult. Because asymptomatic findings are common in cervical radiculopathy, diagnoses based on imaging studies can be inaccurate. Therefore, we investigated whether the application of oblique sagittal reformatted computed tomography (oblique sagittal CT) and three-dimensional sur...

Though dynamic changes in the physical exam of patients being evaluated for cervical spine pathology have been reported, there is limited information on the prevalence and clinical features associated with reflex changes in a population undergoing surgical evaluation for cervical spine pathology. Fifty-one patients with at least grade 1 cervical st...

Background: Transcranial motor evoked potential (TcMEP) is widely used intraoperatively to monitor spinal cord and nerve root function. To our knowledge, there is no report regarding TcMEP signal loss purely caused by patient positioning during the spinal procedure. Purpose: The objective of this article is to report an intraoperative TcMEP sign...

We demonstrate the setup and workflow of performing robotic spine surgery using the Mazor XTM system (MAZOR Robotics Inc, Orlando, Florida) in this video. An illustrative case was presented, including detailed steps for S2AI screw and lumbar pedicle screw placement using robotic assistance. A step-by-step narration is provided along with discussion...

Objective: The S2-alar-iliac (S2AI) screw is an increasingly popular method for spinopelvic fixation. The technique of freehand S2AI screw placement has been recently described. The purpose of this study was to demonstrate, through a CT imaging study of patients with spinal deformity, that screw trajectories based on the posterior superior iliac s...

Background: We aim to demonstrate the safety and efficacy of utilizing 3D-printed spine models to facilitate freehand pedicle screw placement in complex spinal deformity correction. Currently there is no data on using 3D-printed models for freehand pedicle screw placement spinal deformity correction. Methods: All patients undergoing spinal defor...

Study Design A narrative literature review. Objectives To review the surgical techniques of posterior screw fixation in the subaxial cervical spine. Methods A broad literature review on the most common screw fixation techniques including lateral mass, pedicle, intralaminar and transfacet screws was performed on PubMed. The techniques and surgical...

Background: Greater trochanteric pain syndrome (GTPS) is a relatively common diagnosis among the general population. Objective: We aim to determine the prevalence of GTPS among patients who presented to the spine clinic. Methods: Medical records of patients who were evaluated in the spine clinic were reviewed over a 12-month period (4/1/2016 t...

We provide a step-by-step technique guide for performing anterior cervical foraminotomy in this video. An illustrative case was presented with detailed narration and a discussion of surgical nuances. Anterior cervical foraminotomy can be an effective treatment strategy for patients with unilateral cervical radiculopathy without the need for cervica...

We demonstrate the surgical resection of a cervical dumbbell tumor in a patient who presented with progressive weakness over 3 mo. He was found to have a large C2-C3 dumbbell-shaped lesion with bony destruction on preoperative imaging. The patient subsequently underwent successful gross total resection of the tumor and had dramatic improvement in n...

Background: Spinopelvic fixation is an integral part of achieving solid fusion across the lumbosacral junction, especially in deformity procedures requiring substantial correction or long-segment constructs. Traditional S2-alar-iliac (S2AI) screw-placement techniques utilize fluoroscopy, increasing operative time and radiation exposure to the pati...

The distal adding-on phenomenon is a known complication after surgical treatment of adolescent idiopathic scoliosis (AIS) that can lead to loss of deformity correction, worsening pain, wedging, and degeneration of the adjacent intervertebral disc, as well as the need for revision surgery. Various factors have been associated with the adding-on phen...

Study Design Retrospective review of high-dose tranexamic acid (TXA) use in consecutive patients. Objective To determine the safety profile of a high-dose TXA protocol in complex adult spinal deformity patients. Summary of Background Data Adult spinal deformity (ASD) surgery may involve significant amounts of blood loss, especially when various o...

The goals of cervical deformity surgery include deformity correction, restoration of horizontal gaze, decompression of neural elements, spinal stabilization with a biomechanically sound construct, and meticulous arthrodesis technique to prevent pseudoarthrosis and minimizing surgical complications. Many different surgical options exist, but selecti...

Purpose The primary correlate to survival and preservation of neurologic function in patients suffering from an acute ischemic stroke is time from symptom onset to initiation of therapy and reperfusion. Communication and coordination among members of the stroke team are essential to maximizing efficiency and subsequently early reperfusion. In this...

Study Design: Retrospective review of high-dose tranexamic acid (TXA) use in consecutive patients. Objective: To determine the efficacy and safety profile of a high-dose TXA protocol in complex adult spinal deformity patients. Summary of Background Data: Adult spinal deformity (ASD) surgery may involve significant amounts of blood loss, especiall...

Study Design: Retrospective Objectives: To evaluate the effectiveness of using motor evoked potentials to monitoring lumbar nerve root function during spinal surgery. Background: Intraoperative neurophysiological monitoring (IONM) plays an important role during modern spinal surgery. Somatosensory evoked potentials (SSEPs) and motor evoked potent...

A sagittal split fracture of the C1 lateral mass is an unstable subtype of C1 fractures and has a high propensity for developing late deformities and pain with nonoperative management. A primary internal fixation of this type of fracture has been recently described with good clinical outcomes and preservation of motion. We present a modified techni...

Vascular anomalies involving the V3 segment of the vertebral artery are common and may complicate posterior atlantoaxial instrumentation. We report a patient with a fenestrated vertebral artery that underwent successful C1-2 instrumentation and fusion. Various vertebral artery anomalies are discussed with a review of pertinent literature.

Vein of Galen malformations (VoGMs) are rare vascular malformations resulting from persistent shunting of primitive choroidal vessels into the median prosencephalic vein of Markowski. VoGMs are associated with poor clinical outcome with a reported 76.7% mortality if left untreated. We present an exceedingly rare case of a giant, untreated VoGM meas...

Study Design: Retrospective review of high-dose tranexamic acid (TXA) use in consecutive patients. Objective: To determine the efficacy and safety profile of a high-dose TXA protocol in complex adult spinal deformity patients. Summary of Background Data: Adult spinal deformity (ASD) surgery may involve significant amounts of blood loss, especiall...

Introduction: Anterior lumbar interbody fusion (ALIF) is a well-established technique to achieve lumbar spine fusion with various indications including degenerative disc disease, spondylolisthesis, recurrent disc herniation, adjacent level disease, pseudoarthrosis, as well as being used as part of the overall strategy to restore sagittal balance. A...

Orbital cellulitis, also known as postseptal cellulitis, is a serious condition frequently associated with paranasal sinusitis, with the potential risk of blindness if diagnosis and treatment are delayed (1). Patients with orbital cellulitis usually present with periorbital edema, pain, and restricted extraocular movement, thus facilitating a promp...

Aortic dissection is a cardiovascular emergency in which a false lumen is created within the aorta via a tear in the intima. Depending on the location and size of the dissection, arterial blood flow to various end organs can be affected, which is potentially life threatening. Various presentations of aortic dissection include sudden severe chest an...