Thoracoscopic discectomy and instrumented fusion using a minimally invasive plate system: surgical technique and early clinical outcome.

OBJECT: The use of minimally invasive noninstrumented fusions has increased as thoracoscopic approaches to the spine have evolved. The addition of instrumentation is infrequent, in part because of the lack of a minimally invasive implant system. The authors describe a technique for thoracoscopic plating after discectomy and report early clinical outcomes. METHODS: After a standard endoscopic discectomy and partial corpectomy and before exposure of the ventral thecal sac, the authors implanted a polyaxial screw and clamping element under fluoroscopic guidance. Reconstruction involves placement of autograft in the defect and subsequent placement of the remainder of the screw/plate construct with 2 screws per vertebral level. RESULTS: Twenty-five patients underwent thoracoscopic and thoracoscopy-assisted discectomies and fusion in which the aforementioned plate system was used. Of 19 patients presenting with pain, 10 had 6-month clinical follow-up with a greater than 50% reduction in visual analog scale score, which continued to improve up to 2 years postoperatively. There were 3 cases of pneumonia, 3 CSF leaks, 1 chyle leak, and 1 death due to a massive pulmonary embolus on the 1st postoperative day. CONCLUSIONS: The authors conclude that thoracoscopic discectomy and plate-instrumented fusion can be achieved with acceptable results and morbidity. Further studies should evaluate the role of instrumented fusions after thoracoscopic discectomy in larger groups of patients and during a longer follow-up period.

Intermediate segment degeneration after noncontiguous anterior cervical fusion.

BACKGROUND: Studies suggest that the annual incidence of symptomatic adjacent segment disease is 2-3%. Because biomechanical studies have shown increased stress at levels adjacent to a fusion mass, some surgeons have advocated including the normal level in the fusion construct in patients presenting with noncontiguous cervical spondylosis requiring surgical intervention. Our objective was to evaluate the incidence of adjacent segment disease (ASD) in intermediate segments in noncontiguous anterior cervical fusion. METHOD: We reviewed patients who underwent noncontiguous anterior cervical arthrodesis between 1985 and 2007. The primary outcome was the presence of symptomatic degeneration at the intermediate segment in noncontiguous fusions. Secondary outcomes were visual analog scale (VAS) scores and overall neurologic outcome. RESULTS: Seventeen cases of noncontiguous anterior cervical fusion were included. None had symptomatic ASD at the intervening level during mean follow-up of 26 months. Thirteen of 17 patients demonstrated postoperative neurological improvement; four had no change. Overall symptomatic outcome was judged as significantly improved, moderately improved, and unchanged in 11, two, and four patients, respectively. A mean five-point improvement in the VAS score was seen at 3-month follow-up, with continued improvement at 24 months. Among the 37 levels fused, three levels in two patients showed evidence of pseudarthrosis, one of which remained asymptomatic during the follow-up period. CONCLUSIONS: We observed neurological and clinical overall improvement in our series of patients after noncontiguous fusions without evidence of increased degeneration requiring treatment at the intermediate segment. We believe this technique is safe and effective without increased postoperative or long-term morbidity.

The development of neurosurgery at the University of Utah, 1955-2009.

Located in the geographic Intermountain West, the Department of Neurosurgery at the University of Utah has undergone remarkable growth and transformation since the appointment of the first full-time clinical faculty member in 1955. The Department has provided broad neurosurgical services to an expanding community while fulfilling its academic mission of pushing the frontiers within neurosurgical subspecialties. The history of neurosurgery in the Salt Lake Valley and the achievements of the Department of Neurosurgery, including the seminal development of early cranial stereotactic devices, are reviewed in this article.

Atlantoaxial transarticular screw fixation: update on technique and outcomes in 269 patients.

BACKGROUND: Transarticular screw (TAS) fixation is our preferred method for stable internal fixation of the atlantoaxial joint because of its excellent outcomes, versatility, and cost-effectiveness. OBJECTIVE: In this article, we update our series of patients who have undergone TAS fixation, with attention to surgical technique, planning, complication avoidance, and anatomic suitability. METHODS: We retrospectively reviewed 269 patients (150 women, 119 men; average age, 52.9 years; age range, 17-90 years) who underwent placement of at least 1 TAS. In total, 491 TASs were placed for stabilization necessitated by various pathologic conditions. The mean follow-up period was 15.7 months (range, 0-106 months). RESULTS: Fusion was achieved in 99% of 198 patients monitored until fusion or nonunion requiring revision, or for 2 years. Forty-five patients had a complication, for a rate of 16.7%. Five early patients had vertebral artery injuries, 1 of which was bilateral and fatal. No recent patients had vertebral artery injuries. Other complications did not result in neurologic morbidity. Review of all atlantoaxial fusions by the senior author (R.I.A.) revealed that the TAS fixation technique could be successfully applied in 86.7% of sides considered. The main reasons for inapplicability were anatomic (recognized on preoperative planning) in 77% and abandonment secondary to concern about possible vertebral artery injury on the first side attempted in 13.8%. CONCLUSION: The placement of TASs is safe and effective for stabilizing the atlantoaxial articulation. Refinements in technique, such as 3-dimensional stereotactic workstation for trajectory planning, have reduced the rate of serious complications. Clinical outcomes are excellent, with nearly 100% of patients achieving stable bony union.

Anterior fixation of odontoid fractures in an elderly population.

OBJECT: Fractures of the odontoid process are the most common fractures of the cervical spine in patients over the age of 70 years. The incidence of fracture nonunion in this population has been estimated to be 20-fold greater than that in patients under the age of 50 years if surgical stabilization is not used. Anterior and posterior approaches have both been advocated, with excellent results reported, but surgeons should understand the drawbacks of the various techniques before employing them in clinical practice. METHODS: A retrospective review was undertaken to identify patients who had direct fixation of an odontoid fracture at a single institution from 1991 to 2006. Patients were followed up using flexion-extension radiographs, and stability was evaluated as bone union, fibrous union, or nonunion. Patients with bone or fibrous union were classified as stable. In addition, the incidence of procedure- and nonprocedure-related complications was extracted from the medical record. RESULTS: Of the 57 patients over age 70 who underwent placement of an odontoid screw, 42 underwent follow-up from 3 to 62 months (mean 15 months). Stability was confirmed in 81% of these patients. In patients with fixation using 2 screws, 96% demonstrated stability on radiographs at final follow-up. Only 56% of patients with fixation using a single screw demonstrated stability on radiographs. In the immediate postoperative period, 25% of patients required a feeding tube and 19% had aspiration pneumonia that required antibiotic treatment. CONCLUSIONS: Direct fixation of Type II odontoid fractures showed stability rates > 80% in this challenging population. Significantly higher stabilization rates were achieved when 2 screws were placed. The anterior approach was associated with a relatively high dysphagia rate, and patients must be counseled about this risk before surgery.

Use of allograft bone for posterior C1-2 fusion.

OBJECT: An iliac crest autograft is the gold standard for bone grafting in posterior atlantoaxial arthrodesis but can be associated with significant donor-site morbidity. Conversely, an allograft has historically performed suboptimally for atlantoaxial arthrodesis as an onlay graft. The authors have modified a bone grafting technique to allow placement of a bicortical iliac crest allograft in an interpositional manner, and they evaluated it as an alternative to an autograft in posterior atlantoaxial arthrodesis. METHODS: The records of 89 consecutive patients in whom C1-2 arthrodesis was performed between 2001 and 2005 were reviewed. RESULTS: Forty-seven patients underwent 48 atlantoaxial arthrodeses with an allograft (mean follow-up 16.1 months, range 0-49 months), and 42 patients underwent autograft bone grafting (mean follow-up 17.6 months, range 0-61.0 months). The operative time was 50 minutes shorter in the allograft (mean 184 minutes, range 106-328 minutes) than in the autograft procedure (mean 234 minutes, range 154-358 minutes), and the estimated blood loss was 50% lower in the allograft group than in the autograft group (mean 103 ml [range 30-200 ml] vs mean 206 ml [range 50-400 ml], respectively). Bone incorporation was initially slower in the allograft than in the autograft group but equalized by 12 months postprocedure. The respective fusion rates after 24 months were 96.7 and 88.9% for autografts and allografts. Complications at the donor site occurred in 16.7% of the autograft patients, including 1 pelvic fracture, 1 retained sponge, 1 infection, 2 hernias requiring repair, 2 hematomas, and persistent pain. CONCLUSIONS: The authors describe a technique for interpositional bone grafting between C-1 and C-2 that allows for the use of an allograft with excellent fusion results. This technique reduced the operative time and blood loss and eliminated donor-site morbidity.

Transoral approach and extended modifications for lesions of the ventral foramen magnum and craniovertebral junction.

OBJECTIVES: To describe our method of performing the transoral approach and the extended approaches to the ventral foramen magnum and craniovertebral junction and review the technical aspects and operative nuances. DESIGN: Review. RESULTS: The transoral approach provides direct midline exposure to access extradural disease located at the craniovertebral junction and ventral foramen magnum. The corridor of exposure is generally limited by the extent to which the patient can open his or her mouth. The location of the hard palate relative to the craniovertebral junction limits superior exposure, whereas the mandible and base of the tongue limit the inferior exposure. In most cases, exposure can be obtained from the inferior clivus to the middle to lower C2 vertebral body. Extended transoral approaches can be performed to increase exposure if necessary. These approaches include transmaxillary (Le Fort I maxillotomy), transmaxillary with a midline palatal split (extended "open-door" maxillotomy), transpalatal, and median labiomandibular glossotomy (transmandibular split). CONCLUSIONS: The transoral approach effectively provides direct access to extradural midline lesions of the craniovertebral junction. A specialized retractor system can expose the inferior clivus to the C2 body. Extended approaches as described can access lesions that extend beyond these limits.

The utility of MRI in the evaluation of odontoid fractures.

STUDY DESIGN: Retrospective radiographic review. OBJECTIVE: The purpose of this study was to reassess the utility of magnetic resonance imaging (MRI) in the assessment of type II and shallow type III odontoid fractures. SUMMARY OF BACKGROUND DATA: The authors of previous studies have reported a 10% incidence of transverse atlantal ligament (TAL) injury with odontoid fractures and suggested that all odontoid fractures be evaluated preoperatively with MRI. METHODS: A retrospective radiographic review was performed on all odontoid fractures treated with anterior screw fixation from 1987 to 2006. Patients were not screened for TAL injury with MRI or dynamic radiographs before surgery. Each patient had dynamic studies using intraoperative fluoroscopy after screw placement. Evidence of TAL injury was also evaluated on follow-up radiographs by measuring the atlantodental interval (ADI) on neutral, flexion, and extension films. For the purpose of this study, an ADI>3 mm indicated possible TAL injury. Neutral follow-up radiographs were available for 77 patients (mean follow-up, 17.5 mo), and flexion/extension films were available for 34 patients (mean follow-up, 16.4 mo). The mean ADI of the patients with neutral films was 1.1 mm (range=0.5 to 2.1 mm). The mean ADI of the patients with flexion/extension films was 1.2 mm (range=0.6 to 1.8 mm) for flexion and 1.2 mm for extension (range=0.5 to 2.8 mm). There was no evidence of atlantoaxial instability to suggest TAL disruption. CONCLUSIONS: The results of our study demonstrate that the patients with type II and shallow type III odontoid fractures do not require MRI screening for TAL injury. We found no cases of patients with late instability to suggest that a TAL injury was missed.

Comparison of fusion assessment techniques: computer-assisted versus manual measurements.

OBJECT: Fusion assessment after cervical arthrodesis can be subjective. Measures such as bridging bone quantification or extent of (limited) motion on dynamic studies are common but difficult to interpret and fraught with biases. We compared manual measurement and computer-assisted techniques in assessing fusion after anterior cervical discectomy and fusion (ACDF). METHODS: One hundred patients who underwent ACDF (512 intervertebral levels) were randomly selected for this radiographic review (follow-up 3-36 months). Two assessment techniques were performed by different observers, with each blinded to the results of the other. The manual spinous process displacement measurement technique was used to calculate motion between the spinous processes under magnification on a digital imaging workstation. Computer-assisted measurements of intervertebral angular motion were made using Quantitative Motion Analysis (QMA) software. Fusion criteria were arbitrarily set at 1 mm of motion for the manual technique and 1.5 degrees of angular motion for the QMA technique. RESULTS: The manual measurement technique revealed fusion in 61.7% (316 of 512) of the interspaces assessed, and QMA revealed fusion in 64.3% (329 of 512). These two assessment techniques agreed in 87.5% of cases, with a correlation coefficient of 0.68 between the two data sets. In cases in which the two techniques did not agree, QMA revealed fusion and the manual measurement revealed nonfusion in 64% of the disagreements; 98% of the disagreements occurred when motion was < 2 mm or 2 degrees. CONCLUSIONS: Although osseous fusion after arthrodesis remains difficult to assess, new computer-assisted techniques may remove the subjectivity generally associated with assessing fusion.

Surgical treatment of nonrheumatoid atlantoaxial degenerative arthritis producing pain and myelopathy.

STUDY DESIGN: A retrospective review. OBJECTIVE: The purpose of this study was to evaluate the clinical and pathologic findings and surgical treatment outcomes for atlantoaxial osteoarthritis. SUMMARY OF BACKGROUND DATA: Nonrheumatoid atlantoaxial osteoarthritic degeneration can occur at either the atlantodental articulation or lateral mass articulations. This condition may present with neck pain or myelopathy in the setting of a compressive degenerative pannus. There is a paucity of literature on this topic with only case reports and small case series. METHODS: A retrospective chart review was performed to identify patients treated for C1-C2 osteoarthritis. Patient demographics, clinical presentation, neurologic examination, visual analog pain scores, radiographic findings, surgical treatment, outcomes, and complications were recorded for each patient. RESULTS: Twenty-six patients (18 with pannus at the atlantodental articulation and 8 primarily with lateral mass articulation arthritis; 10 men, 16 women; mean age 74 years) were surgically treated for atlantoaxial osteoarthritis. Eleven patients presented primarily with complaints related to myelopathy (all with a degenerative pannus) and 15 presented with cervicalgia only. All patients were treated with posterior atlantoaxial arthrodesis, and 13 patients with myelopathy or severe canal compromise from an irreducible subluxation also had transoral odontoidectomy. All myelopathic patients had improvement in neurologic function (10 of 11 improved 1 Ranawat grade). Neck pain improved in 93% of patients with preoperative neck pain complaints (mean visual analog score before surgery = 7.0, follow-up = 1.3). Fusion was demonstrated in all patients with adequate follow-up. CONCLUSION: Atlantoaxial osteoarthritis can result in neck pain and myelopathy. In the setting of a degenerative pannus and myelopathy, most patients will improve neurologically after transoral decompression and arthrodesis. Patients with pannus and no myelopathy were effectively treated with posterior fusion alone, although 2 with irreducible subluxation required an initial transoral decompression to allow realignment before fusion. Posterior arthrodesis alone provided significant pain relief in most patients.

The lasso technique for posterior C1-C2 fusion.

OBJECTIVE: Posterior atlantoaxial arthrodesis requires placement of a bone graft in a properly prepared environment that includes decorticated bony surfaces, compressive forces between graft and native bone, and limited motion. To achieve posterior atlantoaxial arthrodesis, various cable-and-graft constructs have been used, all of which require an intact posterior arch of C1. For patients who lack an intact arch owing to congenital, iatrogenic, or traumatic causes, we have devised the "lasso technique," which uses the remnants of the posterior arch of C1 for placement of the graft to achieve fusion isolated to C1-C2 or to be part of an occipitocervical construct. METHODS: A retrospective record review was conducted of all patients who underwent the lasso technique. Clinical and radiographic history, perioperative course, and time to fusion were recorded. We describe the technique in detail. RESULTS: During the last 13 years, we have used this technique successfully in five female and four male patients. The absent or incompetent posterior arch was a congenital defect in one patient, a result of prior surgical removal in four patients, and caused by fracture associated with prior failed fusion attempts in four other patients. All patients experienced successful fusion after an average of 6.8 months. CONCLUSION: Securing a bone graft in the absence of an intact C1 lamina is a challenge when a patient presents with atlantoaxial instability. We have devised the lasso technique to secure an interpositional C1-C2 graft using the remnants of the posterior atlantal arch. Although this technique has been required relatively infrequently, we have found it to be valuable and effective in our practice.

Chylorrhea: a rare complication of thoracoscopic discectomy of the thoracolumbar junction. Case report.

The thoracic duct along with the cisterna chyli is a major lymphatic pathway near the anterior thoracolumbar spine. Despite the fragile nature of the lymphatic system and its proximity to the spinal column, chylorrhea is rarely encountered by spine surgeons. The authors present a unique case of chylorrhea associated with a left thoracoscopic, transdiaphragmatic discectomy and fusion for a T12-L1 herniated disc. The anomalous location of the thoracic duct at the left lateral vertebral column contributes to this unusual complication.

Surgical management of cervical myelopathy: indications and techniques for multilevel cervical discectomy.

BACKGROUND CONTEXT: Surgery is usually required for treatment of cervical myelopathy to decompress the neural elements, restore lordosis, and stabilize the spine. By addressing these problems, the neurological deterioration may be halted. PURPOSE: Multilevel cervical discectomy and fusion offers several advantages over other approaches. The authors describe the technique, discuss the indications, and present the potential complications associated with it. METHODS: Decompression is achieved via discectomy and subsequent removal of the osteophytes using a curetting technique. Preparation of end plates in a parallel fashion allows for gapless grafting of allograft bone for enhancement of fusion. A dynamic plate and screw system strengthens the construct. RESULTS: A high rate of fusion can be obtained using the technique of multilevel cervical discectomy and fusion with acceptable levels of complications. It is especially useful in cases of spondylosis that have a kyphotic deformity because, in addition to anterior decompression, it allows reconstruction of the spine to help restore a lordotic curvature. CONCLUSIONS: Multilevel cervical discectomy and fusion has proven to be very effective in decompressing and stabilizing the spine for treatment of cervical myelopathy.

Axially dynamic implants for stabilization of the cervical spine.

OBJECTIVE: Subsidence is a naturally occurring process that is observed during aging and after spine surgery. Rigid cervical spine instrumentation is excellent for stabilizing the spine. These devices, however, also retard subsidence after surgery. Thus, the implant carries much of the axial load, rather than sharing the axial load with the bone graft. This results in an increased incidence of construct failures, pseudoarthrosis, or both, which often occur late in the postoperative course. METHODS: In contrast, dynamic implants allow normal (natural) subsidence to occur, while effectively stabilizing the spine by preventing translation, rotation, and angular deformation. Load sharing, which works with, instead of against, the normal biology of bone healing, occurs with axially dynamic implants, resulting in more robust and earlier fusions. RESULTS: Diminished incidences of construct failures have been reported with dynamic implants. CONCLUSION: Dynamic implants seem to be the system of choice for ventral cervical stabilization in selected patients.

Decompression of cavernous sinus meningioma for preservation and improvement of cranial nerve function. Technical note.

Meningiomas are the most common tumors affecting the cavernous sinus (CS). Despite advances in microsurgery and radiosurgery, treatment of CS meningiomas remains difficult and controversial. As in cases of other meningiomas, the goal of treatment for CS meningioma is long-term growth control and preservation of neural function. Gross-total resection, the ideal treatment for meningioma, is not always possible to obtain in patients with CS meningiomas with an acceptable level of morbidity. Therefore, microsurgery and radiosurgery have recently been advocated as a combined therapy to achieve good control of tumor growth and favorable functional outcome. The authors describe a technique in which tumor volume can be reduced to a minimal residual amount, while preserving cranial nerve function. This enables the smallest field to be treated radiosurgically. The optic nerve is decompressed, and the tumor mass is reduced to provide at least a 5-mm interpositional distance between the optic nerve and the residual lesion. Direct decompression of the CS, with opening of the lateral and superior sinus walls, and piecemeal removal of the tumor in "safe" locations are performed to facilitate an improvement in cranial nerve function. The authors describe the use of this technique in a series of patients and demonstrate improvement of cranial nerve function in a subset of these patients.

Historical perspectives on the diagnosis and treatment of trigeminal neuralgia.

Since the earliest recorded history of medicine, physicians have been challenged by the difficulty in relieving the great pain experienced by individuals suffering from trigeminal neuralgia (TN). The nature of the pain and the events that incite it have been well described, but effective treatments with acceptable levels of side effects remained elusive until the latter part of the 20th century. As a result, many theories about the origins of TN have been proposed, along with numerous treatment modalities. The pathophysiological causes of TN remain incompletely understood, but the medical and surgical treatment techniques currently used offer effective ways to relieve this extremely painful condition. In this historical review the authors discuss the initial descriptions of tic douloureux, Fothergill disease, and TN, along with various therapeutic interventions and their refinements.

Atlantoaxial transarticular screw fixation: a review of surgical indications, fusion rate, complications, and lessons learned in 191 adult patients.

OBJECT: In this, the first of two articles regarding C1-2 transarticular screw fixation, the authors assessed the rate of fusion, surgery-related complications, and lessons learned after C1-2 transarticular screw fixation in an adult patient series. METHODS: The authors retrospectively reviewed 191 consecutive patients (107 women and 84 men; mean age 49.7 years, range 17-90 years) in whom at least one C1-2 transarticular screw was placed. Overall 353 transarticular screws were placed for trauma (85 patients), rheumatoid arthritis (63 patients), congenital anomaly (26 patients), os odontoideum (four patients), neoplasm (eight patients), and chronic cervical instability (five patients). Among these, 67 transarticular screws were placed in 36 patients as part of an occipitocervical construct. Seventeen patients had undergone 24 posterior C1-2 fusion attempts prior to referral. The mean follow-up period was 15.2 months (range 0.1-106.3 months). Fusion was achieved in 98% of cases followed to commencement of fusion or for at least 24 months. The mean duration until fusion was 9.5 months (range 3-48 months). Complications occurred in 32 patients. Most were minor; however, five patients suffered vertebral artery (VA) injury. One bilateral VA injury resulted in patient death. The others did not result in any permanent neurological sequelae. CONCLUSIONS: Based on this series, the authors have learned important lessons that can improve outcomes and safety. These include techniques to improve screw-related patient positioning, development of optimal instrumentation, improved screw materials and design, and defining the role for stereotactic navigation. Atlantoaxial transarticular screw fixation is highly effective in achieving fusion, and the complication rate is low when performed by properly trained surgeons.

Anterior cervical spinal cord tethering after anterior spinal surgery: case report.

OBJECTIVE AND IMPORTANCE: This is the first reported case of anterior cervical spinal cord tethering after anterior spinal surgery. A mechanistic hypothesis is presented to explain the observed phenomenon. CLINICAL PRESENTATION: A patient developed cervical myelopathy 2 years after multiple anterior cervical discectomies complicated by cerebrospinal fluid leakage. She demonstrated reflex and motor changes as well as neuropathic pain. INTERVENTION: An anterior corpectomy was performed, with opening of the dura and detethering of an arachnoid band and then fusion and plating. CONCLUSION: Reflex and motor changes improved, but pain did not. We hypothesize that mechanical deformation and scar formation after cerebrospinal fluid leakage may have led to tethering of the spinal cord.

Odontoid screw fixation for fresh and remote fractures.

Fractures of the odontoid process are common, accounting for 10% to 20% of all cervical spine fractures. Odontoid process fractures are classified into three types depending on the location of the fracture line. Various treatment options are available for each of these fracture types and include application of a cervical orthosis, direct anterior screw fixation, and posterior cervical fusion. If a patient requires surgical treatment of an odontoid process fracture, the timing of treatment may affect fusion rates, particularly if direct anterior odontoid screw fixation is selected as the treatment method. For example, type II odontoid fractures treated within the first 6 months of injury with direct anterior odontoid screw fixation have an 88% fusion rate, whereas fractures treated after 18 months have only a 25% fusion rate. In this review, we discuss the etiology, biomechanics, diagnosis, and treatment (including factors affecting fusion such as timing and fracture orientation) options available for odontoid process fractures.