Does preoperative magnetic resonance imaging alter the surgical plan in patients with acute traumatic cervical spinal cord injury?

BACKGROUND: Whether magnetic resonance imaging (MRI) adds value to surgical planning for patients with acute traumatic cervical spinal cord injury (ATCSCI) remains controversial. In this study, we compared surgeons' operative planning decisions with and without preoperative MRI. We had two hypotheses: (1) the surgical plan for ATCSCI would not change substantially after the MRI and (2) intersurgeon agreement on the surgical plan would also not change substantially after the MRI. METHODS: We performed a vignette-based survey study that included a retrospective review of all adult trauma patients who presented to our American College of Surgeons-verified level 1 trauma center from 2010 to 2019 with signs of acute quadriplegia and underwent computed tomography (CT), MRI, and subsequent cervical spine surgery within 48 hours of admission. We abstracted patient demographics, admission physiology, and injury details. Patient clinical scenarios were presented to three spine surgeons, first with only the CT and then, a minimum of 2 weeks later, with both the CT and MRI. At each presentation, the surgeons identified their surgical plan, which included timing (none, <8, <24, >24 hours), approach (anterior, posterior, circumferential), and targeted vertebral levels. The outcomes were change in surgical plan and intersurgeon agreement. We used Fleiss' kappa (κ) to measure intersurgeon agreement. RESULTS: Twenty-nine patients met the criteria and were included. Ninety-three percent of the surgical plans were changed after the MRI. Intersurgeon agreement was "slight" to "fair" both before the MRI (timing, κ = 0.22; approach, κ = 0.35; levels, κ = 0.13) and after the MRI (timing, κ = 0.06; approach, κ = 0.27; levels, κ = 0.10). CONCLUSION: Surgical plans for ATCSCI changed substantially when the MRI was presented in addition to the CT; however, intersurgeon agreement regarding the surgical plan was low and not improved by the addition of the MRI. LEVEL OF EVIDENCE: Diagnostic, level II.

Atoh1-lineal neurons are required for hearing and for the survival of neurons in the spiral ganglion and brainstem accessory auditory nuclei.

Atoh1 is a basic helix-loop-helix transcription factor necessary for the specification of inner ear hair cells and central auditory system neurons derived from the rhombic lip. We used the Cre-loxP system and two Cre-driver lines (Egr2(Cre) and Hoxb1(Cre)) to delete Atoh1 from different regions of the cochlear nucleus (CN) and accessory auditory nuclei (AAN). Adult Atoh1-conditional knock-out mice (Atoh1(CKO)) are behaviorally deaf, have diminished auditory brainstem evoked responses, and have disrupted CN and AAN morphology and connectivity. In addition, Egr2; Atoh1(CKO) mice lose spiral ganglion neurons in the cochlea and AAN neurons during the first 3 d of life, revealing a novel critical period in the development of these neurons. These new mouse models of predominantly central deafness illuminate the importance of the CN for support of a subset of peripheral and central auditory neurons.

Free-hand thoracic pedicle screws placed by neurosurgery residents: a CT analysis.

Free-hand thoracic pedicle screw placement is becoming more prevalent within neurosurgery residency training programs. This technique implements anatomic landmarks and tactile palpation without fluoroscopy or navigation to place thoracic pedicle screws. Because this technique is performed by surgeons in training, we wished to analyze the rate at which these screws were properly placed by residents by retrospectively reviewing the accuracy of resident-placed free-hand thoracic pedicle screws using computed tomography imaging. A total of 268 resident-placed thoracic pedicle screws was analyzed using axial computed tomography by an independent attending neuroradiologist. Eighty-five percent of the screws were completely within the pedicle and that 15% of the screws violated the pedicle cortex. The majority of the breaches were lateral breaches between 2 and 4 mm (46%). There was no clinical evidence of neurovascular injury or injury to the esophagus. There were no re-operations for screw replacement. We concluded that under appropriate supervision, neurosurgery residents can safely place free-hand thoracic pedicle screws with an acceptable breach rate.

Math1 expression redefines the rhombic lip derivatives and reveals novel lineages within the brainstem and cerebellum.

The rhombic lip (RL) is an embryonic proliferative neuroepithelium that generates several groups of hindbrain neurons. However, the precise boundaries and derivatives of the RL have never been genetically identified. We use beta-galactosidase expressed from the Math1 locus in Math1-heterozygous and Math1-null mice to track RL-derived cells and to evaluate their developmental requirements for Math1. We uncover a Math1-dependent rostral rhombic-lip migratory stream (RLS) that generates some neurons of the parabrachial, lateral lemniscal, and deep cerebellar nuclei, in addition to cerebellar granule neurons. A more caudal Math1-dependent cochlear extramural stream (CES) generates the ventral cochlear nucleus and cochlear granule neurons. Similarly, mossy-fiber precerebellar nuclei require Math1, whereas the inferior olive and locus coeruleus do not. We propose that Math1 expression delimits the extent of the rhombic lip and is required for the generation of the hindbrain superficial migratory streams, all of which contribute neurons to the proprioceptive/vestibular/auditory sensory network.

Trap-door rib-head osteotomies for posterior placement of expandable cages after transpedicular corpectomy: an alternative to lateral extracavitary and costotransversectomy approaches.

Lateral extracavitary and costotransversectomy approaches have been well described, and they are useful for posterior thoracic corpectomies. However, these approaches require pleural dissection and are associated with welldocumented morbidities, including hemothorax, pneumothorax, and pneumonia. But without removing the rib head, the window through which an expandable cage can be placed from a posterior approach is narrow. Thus, smaller nonexpandable mesh cages or methylmethacrylate constructs are commonly used for anterior column reconstruction. The authors describe a technique of using a "trap-door" rib-head osteotomy that avoids pleural dissection, yet allows a large expandable cage to be placed from an entirely posterior approach.

Reconstruction of C-1 lateral mass with titanium mesh cage after resection of an aneurysmal bone cyst of the atlas.

Aneurysmal bone cysts (ABCs) are rare benign tumors with a prevalence of 0.14 cases per 100,000 people. A majority of cases arise during adolescence, and there is a female predominance. This lesion accounts for 1.4% of all primary bone tumors. Aneurysmal bone cysts occur mainly in the long bones, with spinal involvement in 10-30% of cases. Cervical spine ABCs account for about one-third of spinal ABCs, and atlas involvement occurs in 1% of cases. Resection of ABCs at the atlas is difficult because of the location and the lack of proper instrumentation for reconstruction of C-1. The authors present a case of an ABC at C-1 in a child who underwent resection of the lesion and reconstruction of the lateral mass with a titanium mesh cage.

Posterior transpedicular corpectomy and reconstruction of the axial vertebra for metastatic tumor.

Management of metastatic disease is a significant challenge in modern spinal surgery. Previously, radiation therapy alone was the most commonly employed treatment. Recent data, however, suggest that surgical decompression in addition to radiation therapy improves functional recovery compared with radiation therapy alone. Metastatic disease most commonly affects the thoracic spine. Over the past decade surgical treatment has changed significantly for thoracic disease, shifting from transthoracic resection and reconstruction to single-stage posterolateral approaches that allow transpedicular resection and reconstruction. In posterolateral approaches, patients are spared the morbidity associated with transcavitary approaches while receiving the benefit of radical resection and circumferential reconstruction in a single-stage procedure. The authors report 3 cases in which a similar posterior transpedicular technique, adapted for the cervical spine, was used for intralesional resection of metastatic tumors of the axis.

Transpedicular corpectomy with posterior expandable cage placement for L1 burst fracture.

The surgical management of lumbar burst usually involves either a posterior or an anterior approach. Posterior-only procedures usually rely on ligamentotaxis or manual tamping of bone fragments for decompression of the spinal canal. Transpedicular corpectomies allow for circumferential surgery through a single posterior approach; however, they are rarely done for lumbar burst fractures. The presence of intervening nerve roots is one impediment to the placement of expandable cages to reconstruct the anterior column through the transpedicular approach. Using an adaptation of a technique previously described for the treatment of spinal tumors, we were able to successfully treat a traumatic lumbar burst fracture with an expandable cage from a purely posterior approach. This treatment included decompression of the neural elements, correction of the kyphosis, restoration of vertebral body height and reconstruction of the anterior column using an expandable cage with nerve root preservation. We describe our surgical procedure in this technical note.

Removal of ossified ligamentum flavum via a minimally invasive surgical approach.

Ossified ligamentum flavum (OLF) in the thoracic spine is a rare cause of myelopathy, often presenting with progressive symptomatology over an extended period of time. Surgical decompression via wide laminectomy has been the mainstay of treatment for this symptomatic disease phenomenon, but complications such as kyphotic deformity have developed due to extensive bone removal and release of the posterior tension band. The authors present a case of OLF excised via a minimally invasive microsurgical approach in which an expandable tubular retractor system was used. This approach enables complete decompression of the spinal canal while minimizing nerve, vascular, and musculoskeletal disruption, thus maintaining the native biomechanical disposition of the intact vertebral column.

A novel anterior technique for simultaneous single-stage anterior and posterior cervical release for fixed kyphosis.

The incidence rate of kyphosis of the cervical spine after a laminectomy can be as high as 20% after a multilevel laminectomy. The loss of the posterior tension band leads to increased load on the vertebral body and discs, leading to further degenerative changes and kyphotic deformities. The initial decompression of the spinal cord disappears as the cord is stretched over the anterior lesions. Muscle damage and facet degeneration from prior surgery contribute to additional pain, muscle spasm, and motion. Occasionally prior surgical fusion that fails to address the kyphosis or spontaneous fusion in a kyphotic position (observed more in laminectomies performed in the growing spine) can result in a challenging rigid deformity with anterior vertebral body and lateral mass facet fusion. For this fixed deformity, anterior and posterior release are often necessary for restoration of lordosis, which can result in the need for a 540 degrees procedure. In this report the authors describe an anterior technique for simultaneous anterior and posterior lateral mass release. The vertebral artery is mobilized using this technique, allowing for its lateral retraction. The nerve roots are visualized and retracted superiorly and inferiorly. The lateral mass and facets can then be accessed anteriorly using an osteotome or drill for the release. The authors illustrate this technique in a patient who developed fixed scoliosis and kyphosis of the cervical spine after surgery for degenerative disc disease. To the authors' knowledge, this is the first report of this technique.

Stabilization of the atlantoaxial complex via C-1 lateral mass and C-2 pedicle screw fixation in a multicenter clinical experience in 102 patients: modification of the Harms and Goel techniques.

OBJECT: Stabilization of the atlantoaxial complex has proven to be very challenging. Because of the high mobility of the C1-2 motion segment, fusion rates at this level have been substantially lower than those at the subaxial spine. The set of potential surgical interventions is limited by the anatomy of this region. In 2001 Jürgen Harms described a novel technique for individual fixation of the C-1 lateral mass and the C-2 pedicle by using polyaxial screws and rods. This method has been shown to confer excellent stability in biomechanical studies. Cadaveric and radiographic analyses have indicated that it is safe with respect to osseous and vascular anatomy. Clinical outcome studies and fusion rates have been limited to small case series thus far. The authors reviewed the multicenter experience with 102 patients undergoing C1-2 fusion via the polyaxial screw/rod technique. They also describe a modification to the Harms technique. METHODS: One hundred two patients (60 female and 42 male) with an average age of 62 years were included in this analysis. The average follow-up was 16.4 months. Indications for surgery were instability at the C1-2 level, and a chronic Type II odontoid fracture was the most frequent underlying cause. All patients had evidence of instability on flexion and extension studies. All underwent posterior C-1 lateral mass to C-2 pedicle or pars screw fixation, according to the method of Harms. Thirty-nine patients also underwent distraction and placement of an allograft spacer into the C1-2 joint, the authors' modification of the Harms technique. None of the patients had supplemental sublaminar wiring. RESULTS: All but 2 patients with at least a 12-month follow-up had radiographic evidence of fusion or lack of motion on flexion and extension films. All patients with an allograft spacer demonstrated bridging bone across the joint space on plain x-ray films and computed tomography. The C-2 root was sacrificed bilaterally in all patients. A postoperative wound infection developed in 4 patients and was treated conservatively with antibiotics and local wound care. One patient required surgical debridement of the wound. No patient suffered a neurological injury. Unfavorable anatomy precluded the use of C-2 pedicle screws in 23 patients, and thus, they underwent placement of pars screws instead. CONCLUSIONS: Fusion of C1-2 according to the Harms technique is a safe and effective treatment modality. It is suitable for a wide variety of fracture patterns, congenital abnormalities, or other causes of atlantoaxial instability. Modification of the Harms technique with distraction and placement of an allograft spacer in the joint space may restore C1-2 height and enhance radiographic detection of fusion by demonstrating a graft-bone interface on plain x-ray films, which is easier to visualize than the C1-2 joint.

Drosophila atonal fully rescues the phenotype of Math1 null mice: new functions evolve in new cellular contexts.

Many genes share sequence similarity between species, but their properties often change significantly during evolution. For example, the Drosophila genes engrailed and orthodenticle and the onychophoran gene Ultrabithorax only partially substitute for their mouse or Drosophila homologs. We have been analyzing the relationship between atonal (ato) in the fruit fly and its mouse homolog, Math1. In flies, ato acts as a proneural gene that governs the development of chordotonal organs (CHOs), which serve as stretch receptors in the body wall and joints and as auditory organs in the antennae. In the fly CNS, ato is important not for specification but for axonal arborization. Math1, in contrast, is required for the specification of cells in both the CNS and the PNS. Furthermore, Math1 serves a role in the development of secretory lineage cells in the gut, a function that does not parallel any known to be served by ato. We wondered whether ato and Math1 might be more functionally homologous than they appear, so we expressed Math1 in ato mutant flies and ato in Math1 null mice. To our surprise, the two proteins are functionally interchangeable.

Focal cortical dysplasia: a review of pathological features, genetics, and surgical outcome.

Focal cortical dysplasia (FCD) is found in approximately one-half of patients with medically refractory epilepsy. These lesions may involve only mild disorganization of the cortex, but they may also contain abnormal neuronal elements such as balloon cells. Advances in neuroimaging have allowed better identification of these lesions, and thus more patients have become surgical candidates. Molecular biology techniques have been used to explore the genetics and pathophysiological characteristics of FCD. Data from surgical series have shown that surgery often results in significant reduction or cessation of seizures, especially if the entire lesion is resected.

Breast cancer molecular subtypes: from TNBC to QNBC.

Treatment protocols for breast cancer depend predominantly on receptor status with respect to estrogen (estrogen receptor alpha), progesterone (progesterone receptor) and human epidermal growth factor [human epidermal growth factor receptor 2 (HER2)]. The presence of one or more of these receptors suggests that a treatment targeting these pathways might be effective, while the absence of, or in the case of HER2, lack of overexpression of, all of these receptors, termed triple negative breast cancer (TNBC), indicates a need for the more toxic chemotherapy. In an effort to develop targeted therapies for TNBC, it will be necessary to differentiate among specific TNBC subtypes. The subset of TNBC that expresses androgen receptor (AR) has been determined to express genes consistent with a luminal subtype and therefore may be amenable to therapies targeting either AR, itself, or other pathways typical of a luminal subtype. Recent investigations of the AR signal pathway within breast cancer lead to AR as a significant target for breast cancer therapy with several clinical trials currently in progress. The subclass of TNBC that lacks AR, which we have termed quadruple negative breast cancer (QNBC) currently lacks a defined targetable pathway. Unlike AR-positive TNBC, QNBC predominantly exhibits a basal-like molecular subtype. Several subtypes and related pathway proteins are preferentially expressed in QNBC that may serve as effective targets for treatment, such as ACSL4, SKP2 and EGFR. ACSL4 expression has been demonstrated to be inversely correlated with expression of hormone/growth factor receptors and may thus serve as a biomarker for QNBC as well as a target for therapy. In the following review we summarize some of the current efforts to develop alternatives to chemotherapy for TNBC and QNBC.

Accuracy of body weight perception and obesity among Chinese Americans.

BACKGROUND: Accuracy of body weight perception is an individual's perception of their body weight in comparison with actual body weight and is associated with weight-related behaviors. Chinese Americans have increased risk for obesity but no studies have examined accuracy of body weight perception. METHODS: This study was a descriptive and cross-sectional study, which was conducted in a community health center in New York. Study subjects were all Chinese-American adults. Demographic information, accuracy of perception of body weight, anthropometric measures (weight, height, body mass index [BMI], waist circumference [WC], hip circumference [HC], weight to height ratio, weight to hip ratio), fasting plasma glucose (FPG), glycosylated hemoglobin (HbA1C) and obesity-related diseases (hypertension, diabetes, heart disease, and stroke) were assessed. RESULTS: A total of 162 Chinese Americans were recruited. 52 subjects (32%) did not perceive body weight correctly: 32 subjects had underestimation and 20 subjects had overestimation of body weight. Significant differences were found among subjects in the three groups of different accuracy of body weight perception in terms of gender (p=0.003), age (p=0.003), education years (p=0.047), WC (p<0.001), HC (p≤0.001), weight/height ratio (p=0.001), and BMI (p<0.001). Accuracy of perception of body weight significantly predicted WC (p<0.001), HC (p<0.001), weight to height ratio (p=0.001), BMI (p<0.001) and weight (<0.001) even after controlling for all demographic factors. DISCUSSION AND CONCLUSION: The study identified that around one-third of Chinese Americans did not perceive their body weight correctly. Intervention studies for obesity management in Chinese Americans should address gender difference, target on older subjects, and focus on educating the normal values and significances of WC, HC and HbA1C among Chinese Americans.

Pedicle subtraction osteotomies for the correction of post-traumatic thoracolumbar kyphosis.

Traumatic compression fractures are usually treated non-surgically. In most patients without osteoporosis, such fractures heal without any sequelae. However, some patients develop a post-traumatic kyphosis that can lead to severe pain and disability, refractory to non-surgical management. In such patients, correction of the kyphosis ultimately may be the only definitive treatment. Pedicle subtraction osteotomies have been used in non-traumatic settings to correct kyphotic deformities or restore lordosis in patients in symptomatic positive sagittal balance. We apply this technique in the setting of post-traumatic kyphosis, and we performed the osteotomies at the level of the compression fracture.

Spine and spinal cord emergencies: vascular and infectious causes.

This content presents infectious and vascular spinal emergencies, including epidural abscess, nontraumatic epidural hematoma, vascular malformations, and spinal cord infarction. The spine is subjected to multiple potential insults, such as trauma, infection, ischemia, hemorrhage, tumor, inflammation, and degeneration. All of these processes can lead to the sudden onset of neurologic symptoms, such as motor weaknesses, bowel and bladder incontinence, and sensory changes. Therefore, prompt recognition of these entities is important to reverse or minimize potential neurologic injury. The authors discuss several infectious and vascular spinal emergencies, including epidural abscess, nontraumatic epidural hematoma, vascular malformations, and spinal cord infarction.