Internal Morphology of the Odontoid Process: Anatomic and Imaging Study with Application to C2 Fractures.

OBJECTIVE: Fracture of the odontoid process is a critical injury to diagnose and often treat. The aim of this anatomic study was to present a comprehensive understanding of this part of the C2 vertebra. METHODS: We used 20 C2 vertebrae. Samples underwent imaging (computed tomography [CT] with and without three-dimensional reconstruction, micro-CT, 1.5T magnetic resonance imaging) and sagittal and coronal sectioning using a bone saw. Sectioned specimens were imaged under a digital handheld microscope, and transillumination of the bone was used to highlight its internal trabecular pattern. Three samples underwent infusion of the odontoid process with a hardening substance and were then decalcified. RESULTS: Internal trabecular patterns of the odontoid process of all specimens were discernible. In sagittal and coronal sections, trabecular patterns were highlighted with transillumination, but the patterns were much clearer using the digital microscope. Magnetic resonance imaging and CT provided the least detail of the imaging methods, but the trabecular patterns could be identified. Three-dimensional reconstruction of CT data was the preferred imaging method over magnetic resonance imaging and CT without three-dimensional reconstruction. The most distinct trabecular and cortical patterns were seen using micro-CT. Osteoporosis was seen in 2 specimens (10%). Five specimens (25%) were found to have a subdental synchondrosis. For most specimens, the trabeculae were found throughout the odontoid process. CONCLUSIONS: Improved knowledge of the anatomy, structural composition, and variations within the C2 vertebra may allow for better treatment options and patient care.

Relationship of the lumbar plexus branches to the lumbar spine: anatomical study with application to lateral approaches.

BACKGROUND CONTEXT: Injuries to the lumbar plexus during lateral approaches to the spine are not uncommon and may result in permanent deficits. However, the literature contains few studies that provide landmarks for avoiding the branches of the lumbar plexus. PURPOSE: The present anatomical study was performed to elucidate the course of these nerves in relation to lateral approaches to the lumbar spine. STUDY DESIGN: This is a quantitative anatomical cadaveric study. METHODS: The lumbar plexus and its branches were dissected on 12 cadaveric sides. Metal wires were laid on the nerves along their paths on the posterior abdominal wall. Fluoroscopy was performed in the anteroposterior and lateral positions. The relationships between regional bony landmarks and the branches of the lumbar plexus were observed. RESULTS: When viewed laterally, the greatest concentration of nerves occurred from the posteroinferior aspect of L4, inferior along the posterior one-third of the body of L5, then at the level of the sacral promontory. On the basis of our study, approaches to the anterior two-thirds of the L4 vertebra and anterior third of L5 will result in the lowest chance of lumbar plexus nerve injury. In addition, lateral muscle dissection through the psoas major should be in a superior to inferior direction in order to minimize nerve injury. Laterally, the widest corridor between branches in the abdominal wall was between the subcostal and iliohypogastric nerves. CONCLUSIONS: The findings of our cadaveric study provide surgeons who approach the lateral lumbar spine with data that could decrease injuries to the branches of the lumbar plexus, thus lessening patient morbidity.

Association Between Allogeneic Blood Transfusion and Postoperative Infection in Major Spine Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The objective of this study is to compare the incidence of infection in patients who do and do not receive blood transfusions in major deformity surgery (>8 levels). SUMMARY OF BACKGROUND DATA: Postoperative infections increase morbidity and mortality rates in spine surgery and generate additional costs for the health care system. It has been proposed that blood transfusions increase the risk of wound infection, urinary tract infection, pneumonia, and sepsis. METHODS: A total of 56 patients met the study criteria, receiving spine surgery involving the fusion of 8 levels or more. Patient-specific characteristics, starting and ending hematocrits, number of units transfused and infections including urinary tract infection, wound infection, pneumonia, and sepsis were documented. Differences in infection risk between those who did and did not undergo a transfusion and their 95% confidence intervals were calculated. RESULTS: Groups were similar with respect to baseline and surgical characteristics except for smoking status, operative time, estimated blood loss, and ending hematocrit. The overall infection rate was greater in patients who underwent transfusion than those who did not (36% vs. 10%; P=0.03). Wound infections (n=5) were only observed in those who underwent a transfusion. Smokers were more likely to receive a transfusion and more likely to experience infection. A stratified analysis demonstrated an increased risk of infection associated with transfusion; however, the risk was greater in smokers, suggesting the effect of transfusion on infection could be modified by smoking. Patients undergoing transfusion experienced a significantly longer hospital stay (P=0.01). CONCLUSIONS: Allogeneic red blood cell transfusion in major spine surgery could be a risk factor for postoperative infection. This increased risk seems to be magnified in those who smoke. Further studies are warranted, and risks of blood loss and transfusion-related complications in smokers also potentially merit exploration. LEVEL OF EVIDENCE: Level 3.

Posterior arch C-1 screw technique: a cadaveric comparison study.

OBJECTIVE Posterior atlantoaxial stabilization and fusion using C-1 lateral mass screw fixation has become commonly used in the treatment of instability and for reconstructive indications since its introduction by Goel and Laheri in 1994 and modification by Harms in 2001. Placement of such lateral mass screws can be challenging because of the proximity to the spinal cord, vertebral artery, an extensive venous plexus, and the C-2 nerve root, which overlies the designated starting point on the posterior center of the lateral mass. An alternative posterior access point starting on the posterior arch of C-1 could provide a C-2 nerve root-sparing starting point for screw placement, with the potential benefit of greater directional control and simpler trajectory. The authors present a cadaveric study comparing an alternative strategy (i.e., a C-1 screw with a posterior arch starting point) to the conventional strategy (i.e., using the lower lateral mass entry site), specifically assessing the safety of screw placement to preserve the C-2 nerve root. METHODS Five US-trained spine fellows instrumented 17 fresh human cadaveric heads using the Goel/Harms C-1 lateral mass (GHLM) technique on the left and the posterior arch lateral mass (PALM) technique on the right, under fluoroscopic guidance. After screw placement, a CT scan was obtained on each specimen to assess for radiographic screw placement accuracy. Four faculty spine surgeons, blinded to the surgeon who instrumented the cadaver, independently graded the quality of screw placement using a modified Upendra classification. RESULTS Of the 17 specimens, the C-2 nerve root was anatomically impinged in 13 (76.5%) of the specimens. The GHLM technique was graded Type 1 or 2, which is considered "acceptable," in 12 specimens (70.6%), and graded Type 3 or 4 ("unacceptable") in 5 specimens (29.4%). In contrast, the PALM technique had 17 (100%) of 17 graded Type 1 or 2 (p = 0.015). There were no vertebral artery injuries found in either technique. All screw violations occurred in the medial direction. CONCLUSIONS The PALM technique showed statistically fewer medial penetrations than the GHLM technique in this study. The reason for this is not clear, but may stem from a more angulated "up-and-in" screw direction necessary with a lower starting point.

Advancement of Surgical Visualization Methods: Comparison Study Between Traditional Microscopic Surgery and a Novel Robotic Optoelectronic Visualization Tool for Spinal Surgery.

INTRODUCTION: The operating microscope (OM) has become instrumental in aiding surgeons during key microdissection with greater safety and detail. An exoscope offers similar detail with improved functionality and greater implications for live teaching and improved operating room flow. METHODS: Eleven senior neurosurgery residents and fellows performed unilateral, single-level laminotomies on fresh cadavers using an OM and exoscope. Three attending spine surgeons blinded for the visualization technique used then reviewed and graded each decompression. Data points gathered included time of procedure, grading of decompression (1-5), and complications, including dural tear, nerve root injury, and pars fracture. RESULTS: Operative times between the 2 systems were not significantly different (14.9 minutes OM vs. 15.6 minutes exoscope, P = 0.766). Despite high variability between evaluators in assessing complications and adequacy of decompression, there was no significant difference between either system. Postprocedural surveys indicated greater comfort with the exoscope, greater ease of use, and superior teaching potential for the exoscope over the standard OM. CONCLUSION: In our simulated operating room model, an exoscope is a valid alternative to the standard OM that affords the surgeon greater comfort with greater teaching potential while maintaining many of the microscope's benefits.

Cervical fracture from chronic steroid usage presenting as a stroke: A case report.

INTRODUCTION: Misdiagnosis of Brown-Séquard-like presentations can delay treatment; potentially endangering the positive outcomes a patient might otherwise have had. Stroke mimics can be perceived as signaling the end of urgent investigation and care once stroke is ruled out; however, stroke mimics themselves can require prompt care. Herein, we discuss an extremely rare case where stroke was ruled out, resulting in a lapse in care that lead to an exacerbated hemiparesis over the following week. PRESENTATION OF CASE: We present a patient with an occult cervical spine fracture with extension of the neck, caused by reduced bone density from a chronic steroid regimen. Nine days after the initial onset of her neurological symptoms, the patient presented to the ED with the complaint of left sided weakness and right-sided sensory loss. She was determined to have a left- sided Brown Séquard syndrome, which resolved following anterior cervical discectomy and fusion at C4-C6 and a laminectomy from C4-C6. DISCUSSION: This case indicated that patients with dangerously low bone density should be weaned off chronic steroid therapy to prevent the onset of osteoporotic symptoms early in adulthood. Furthermore, this case emphasizes the importance of continued investigation of symptoms if a stroke is ruled out and the need for more diligent monitoring of bone density of chronic steroid users. CONCLUSION: Stroke mimics can require the same urgency in care and diagnosis as strokes themselves.

The Vertebral Artery Cave at C2: Anatomic Study with Application to C2 Pedicle Screw Placement.

OBJECTIVE: Knowledge of the course of the vertebral artery during instrumentation is of paramount importance. It has been shown that erosion of the C2 pedicle and body can occur due to pulsations of the adjacent vertebral artery. This often results in a "cave" for this segment of the artery. The descriptions of this anatomy are limited. The current study was performed with the hope that these data will be of use to spine surgeons during C2 instrumentation. METHODS: In 40 human adult C2 bone specimens, the position of the vertebral artery in relation to the undersurface of the superior articular facet, pedicle, and C2 body was observed. A classification system was used to better describe these relationships. Pedicle screws were then placed into selected examples of each type. RESULTS: We found type 0 specimens, with no cave, on 8 sides (10%). Types I, II, and III caves with minimal, moderate, and significant encroachment of the pedicle were observed on 40%, 35%, and 27.5% sides, respectively. Type IV caves with erosion into the lateral C2 body and undersurface of the superior articular facet were observed on 12.5% of sides. Although larger caves were found on left sides, this did not reach statistical significance. Pedicle screw placement for types III and IV were most likely to enter the vertebral artery cave (P < 0.05). CONCLUSIONS: Additional osteologic data regarding the course of the vertebral artery while within C2 may decrease morbidity during surgery in this region.

Unilateral Laminotomy with Bilateral Spinal Canal Decompression for Lumbar Stenosis: A Technical Note.

Lumbar stenosis has become one of the most common spinal pathologies and one that results in neurogenic claudication, back and leg pain, and disability. The standard procedure is still an open laminectomy, which involves wide muscle retraction and extensive removal of the posterior spinal structures. This can lead to instability and the need for additional spinal fusion. We present a systemized and detailed approach to unilateral laminotomy for bilateral decompression, which we believe is superior to the standard open laminectomy in terms of intraoperative visualization, postoperative stability, and degree of invasiveness.

Dural-Based Cavernoma of the Posterior Cranial Fossa Mimicking a Meningioma: A Case Report.

Cavernous angiomas usually occur in the parenchyma of both the supra and infratentorial compartments. At times, they can both clinically and radiologically mimic other dural-based lesions. We present a case of a patient with chronic occipital headaches, initially thought to have a meningioma, but proven to be a cavernoma with histological analysis.

Pulmonary Complications following Thoracic Spinal Surgery: A Systematic Review.

Study Design Systematic review. Objective To determine the frequency of pulmonary effusion, pneumothorax, and hemothorax in adult patients undergoing thoracic corpectomy or osteotomy for any condition and to determine if these frequencies vary by surgical approach (i.e., anterior, posterior, or lateral). Methods Electronic databases and reference lists of key articles were searched through September 21, 2015, to identify studies specifically evaluating the frequency of pulmonary effusion, pneumothorax, and hemothorax in patients undergoing thoracic spine surgery. Results Fourteen studies, 13 retrospective and 1 prospective, met inclusion criteria. The frequency across studies of pulmonary effusion ranged from 0 to 77%; for hemothorax, 0 to 77%; and for pneumothorax, 0 to 50%. There was no clear pattern of pulmonary complications with respect to surgical approach. Conclusions There is insufficient data to determine the risk of pulmonary complications following anterior, posterior, or lateral approaches to the thoracic spine. Methods for assessing pulmonary complications were not well reported, and data is sparse.

Effect of steroid use in anterior cervical discectomy and fusion: a randomized controlled trial.

OBJECT Anterior cervical discectomy and fusion (ACDF) is an effective procedure for the treatment of cervical radiculopathy and/or myelopathy; however, postoperative dysphagia is a significant concern. Dexamethasone, although potentially protective against perioperative dysphagia and airway compromise, could inhibit fusion, a generally proinflammatory process. The authors conducted a prospective, randomized, double-blinded, controlled study of the effects of steroids on swallowing, the airway, and arthrodesis related to multilevel anterior cervical reconstruction in patients who were undergoing ACDF at Albany Medical Center between 2008 and 2012. The objective of this study was to determine if perioperative steroid use improves perioperative dysphagia and airway edema. METHODS A total of 112 patients were enrolled and randomly assigned to receive saline or dexamethasone. Data gathered included demographics, functional status (including modified Japanese Orthopaedic Association myelopathy score, neck disability index, 12-Item Short-Form Health Survey score, and patient-reported visual analog scale score of axial and radiating pain), functional outcome swallowing scale score, interval postoperative imaging, fusion status, and complications/reoperations. Follow-up was performed at 1, 3, 6, 12, and 24 months, and CT was performed 6, 12, and 24 months after surgery for fusion assessment. RESULTS Baseline demographics were not significantly different between the 2 groups, indicating adequate randomization. In terms of patient-reported functional and pain-related outcomes, there were no differences in the steroid and placebo groups. However, the severity of dysphagia in the postoperative period up to 1 month proved to be significantly lower in the steroid group than in the placebo group (p = 0.027). Furthermore, airway difficulty and a need for intubation trended toward significance in the placebo group (p = 0.057). Last, fusion rates at 6 months proved to be significantly lower in the steroid group but lost significance at 12 months (p = 0.048 and 0.57, respectively). CONCLUSIONS Dexamethasone administered perioperatively significantly improved swallowing function and airway edema and shortened length of stay. It did not affect pain, functional outcomes, or long-term swallowing status. However, it significantly delayed fusion, but the long-term fusion rates remained unaffected. Clinical trial registration no.: NCT01065961 (clinicaltrials.gov).

Place conditioning to apomorphine in rat models of Parkinson's disease: differences by dose and side-effect expression.

One potential complication of treating Parkinson's Disease (PD) with dopaminergic drugs is dopamine dysregulation syndrome, an addiction-like response to the drug therapy. Here, we assessed whether rats given parkinsonian-like symptoms with a unilateral injection of 6-hydroxydopamine into the medial forebrain bundle (6-OHDA-MFB), exhibit similar behavior. To examine this, we injected these rats or sham-lesioned rats subcutaneously (sc) with apomorphine (APO) at low (0.05mg/kg) and high (1mg/kg) dosage and monitored their conditioned place preference Saline was administered on alternating days. After 4 and 8 conditioned pairings, both rat groups underwent post-conditioning tests in a drug-free state 6-OHDA rats exhibited positive place conditioning to the low dose of APO after 4 and 8 pairings whereas sham-lesioned rats did not (p<0.01). At the high APO dose, sham-lesioned rats showed consistent positive place conditioning, but preferences in 6-OHDA rats were more variable although they all exhibited rotation behavior. Upon further inspection, we noted that contraversive rotation increased over time and this negatively correlated with place conditioning scores. While the absolute number of rotations did not negatively affect preference for the APO-paired chamber, an increase in rotation numbers between pairings did (r=-0.634, p=0.027). Taken together, 6-OHDA rats were more sensitive to the rewarding aspects of APO, but the adverse consequence of rotation diminished this response This model may be ideal to study addiction-like responses in PD.

Iliac bolt fixation: an anatomic approach.

STUDY DESIGN: An illustrative technique display and discussions. OBJECTIVES: Review of traditional and new "anatomic" techniques for placement of iliac-spinal fixation. SUMMARY OF BACKGROUND DATA: Placement of iliac fixation traditionally has been performed using offset connectors, devascularizing the iliac muscles, in addition to the posterior iliac spine. The technique reviewed provides for the screw heads to be placed in a more anatomic position, allowing rods to be laid parallel without the detachment of the erector spinous muscles. METHODS: Utilization of anatomic models and discussion of present surgical technique for iliac bolt fixation (traditional) compared and contrasted to newer technique using the anatomic landmarks and structures of the iliac crest. RESULTS: The anatomic models illustrate and support the utilization of an anatomic technique for fixation due to the lessening of muscle trauma, alignment of the rod systems, and preservation of the cortical surfaces. CONCLUSIONS: The anatomic placement of iliac bolts provides for improved alignment of constructs while addressing spinal deformities. It may also increase screw pullout and construct strength.

Acute cervical fracture or congenital spinal deformity?

BACKGROUND/OBJECTIVE: There are few reports of developmental or congenital cervical spinal deformities. Such cases may be mistaken for traumatically induced fractures, and additional treatment may ensue. METHODS: A retrospective analysis was performed to identify patients with congenital cervical spine deformities. These patients were matched with a confirmed traumatic spinal fracture population with similar demographic features. Patients were analyzed for age, gender, imaging findings (plain roentgenograms including dynamic flexion and extension views, computed tomography scan, and MRI), neurologic status, and subjective complaints of pain. RESULTS: Thirty-six individuals were included in the final analysis, 7 with congenital abnormalities and 29 with radiographically confirmed traumatic injuries. Patients with congenital abnormalities had significantly less soft-tissue swelling compared with the population with traumatic fractures (P < 0.001). Furthermore, those with congenital defects presented with lesser degrees of vertebral subluxation (0.29 mm vs 7.24 mm) (P < 0.0001) and without neurologic deficits (P < 0.0001). CONCLUSIONS: Congenital abnormalities, though rare, can be mistaken for traumatic fractures of the spine. Physicians should note any evidence of soft-tissue swelling, neurologic deficits, degree of subluxation, and radiographic evidence of pedicle absence because these characteristics often provide insight into the specific etiology of the observed spinal deformity (congenital vs traumatic).

Athletes returning to play after cervical spine or neurobrachial injury.

The treatment algorithms for athletes with spine injuries follow similar guidelines as those for non-athletes in terms of deciding between surgical intervention and non-operative management. However, the athlete has unique postoperative demands and the decision to "allow" an athlete to return to competitive sports after a spinal or plexus injury can be difficult. This article reviews the several studies, available guidelines and peer-reviewed publications to aid in the decisions to allow athletes to return to sports. A set of recommendations concerning return to play after a spinal injury is provided.

Mortality rates in geriatric patients with spinal cord injuries.

OBJECT: The authors undertook this study to evaluate the incidence of spinal cord injury (SCI) in geriatric patients (> or = 70 years of age) and examine the impact of patient age, extent of neurological injury, and spinal level of injury on the mortality rate associated with traumatic SCI. METHODS: A prospectively maintained SCI database (3481 patients) at a single institution was retrospectively studied for the period from 1978 through 2005. Parameters analyzed included patient age, admission American Spinal Injury Association (ASIA) motor score, level of SCI, mechanism of injury, and mortality data. The data pertaining to the 412 patients 70 years of age and older were compared with those pertaining to the younger cohort using a chi-square analysis. RESULTS: Since 1980, the number of SCI-related hospital admissions per year have increased fivefold in geriatric patients and the percentage of geriatric patients within the SCI population has increased from 4.2 to 15.4%. In comparison with younger patients, geriatric patients were found to be less likely to have severe neurological deficits (greater percentage of ASIA Grades C and D injuries), but the mortality rates were higher in the older age group both for the period of hospitalization (27.7% compared with 3.2%, p < 0.001) and during 1-year follow-up. The mortality rates in this older population directly correlate with the severity of neurological injury (1-year mortality rate, ASIA Grade A 66%, Grade D 23%, p < 0.001). The mortality rate in elderly patients with SCI has not changed significantly over the last two decades, and the 1-year mortality rate was greater than 40% in all periods analyzed. CONCLUSIONS: Spinal cord injuries in older patients are becoming more prevalent. The mortality rate in this patient group is much greater than in younger patients and should be taken into account when aggressive interventions are considered and in counseling families regarding prognosis.