We Tabulated and Organized American Board of Neurological Surgeons Primary Exam Keywords (2015-2023) so You Don't Have to.

Background Passing the American Board of Neurological Surgeons (ABNS) Primary Exam is required for residents in training. Both the program directors and residents are given keywords of the exam afterward in the hope to help program directors determine their relative strengths and weakness. We have organized and tabulated these keywords for neurosurgery residents' benefit. Methodology We collected and analyzed ABNS Primary Exam keywords (2015-2023) in each of the exam's main categories for trends and recurrences. We examined the overall passing rates among first-time credit test takers. The frequency of each subcategory was calculated as a percentage within its corresponding category. Recurrent keywords were grouped together with their corresponding years and categorized as once, twice, or thrice and greater occurrences; the last category was considered to be high-yield keywords. Results The number of questions in Neurosciences and Neurology has decreased over the years while Neurosurgery and Critical Care questions have increased. Similarly, there are fewer keyword repeats in Neurosciences and Neurology. The most repeated keywords are in Neuroimaging. The most common keywords are presented and listed along with the years of occurrences. Overall, the passing rate among first-time credit test takers is over 90%. Conclusions Neurosurgery residents can consider the common keywords as a guide in preparation for the ABNS Primary Exam.

Effect of Body Mass Index on Paddle Lead Spinal Cord Stimulator Safety Implantation for Chronic Pain Management.

OBJECTIVE: Spinal cord stimulators (SCS) represent an effective treatment for patients with chronic pain issues. This study examines extremely obese patients (body mass index [BMI] ≥40) as appropriate surgical candidates for paddle lead SCS trial via partial thoracic laminectomy and whether obesity impacts implantation safety. METHODS: A retrospective review of patients treated with partial thoracic laminectomy and paddle lead SCS trial between October 1, 2016 and September 30, 2019 was performed. The primary outcome was implantation safety (complication rate within minimum of 90 days) in patients with extreme obesity (BMI ≥40) compared with patients with BMI <40 and secondary outcome was effectiveness (successful trial leading to final implantation). Seventy-three patients underwent SCS trial. RESULTS: Four (5.48%) patients developed complications with only 1 patient in the BMI ≥40 cohort (not statistically significant). Overall trial success rate was 82.2% (60/73) with statistically significant higher success rates among patients with a BMI ≥40 (93.3% vs. 74.4%, P = 0.0183). CONCLUSIONS: We conclude that paddle lead SCS trial in extremely obese patients is reasonable to offer with the expectation of similar safety concerns as those for patients with a lower BMI.

The 'Lumbar Fusion Outcome Score' (LUFOS): a new practical and surgically oriented grading system for preoperative prediction of surgical outcomes after lumbar spinal fusion in patients with degenerative disc disease and refractory chronic axial low back pain.

In order to evaluate the predictive effect of non-invasive preoperative imaging methods on surgical outcomes of lumbar fusion for patients with degenerative disc disease (DDD) and refractory chronic axial low back pain (LBP), the authors conducted a retrospective review of 45 patients with DDD and refractory LBP submitted to anterior lumbar interbody fusion (ALIF) at a single center from 2007 to 2010. Surgical outcomes - as measured by Visual Analog Scale (VAS/back pain) and Oswestry Disability Index (ODI) - were evaluated pre-operatively and at 6 weeks, 3 months, 6 months, and 1 year post-operatively. Linear mixed-effects models were generated in order to identify possible preoperative imaging characteristics (including bone scan/99mTc scintigraphy increased endplate uptake, Modic endplate changes, and disc degeneration graded according to Pfirrmann classification) which may be predictive of long-term surgical outcomes . After controlling for confounders, a combined score, the Lumbar Fusion Outcome Score (LUFOS), was developed. The LUFOS grading system was able to stratify patients in two general groups (Non-surgical: LUFOS 0 and 1; Surgical: LUFOS 2 and 3) that presented significantly different surgical outcomes in terms of estimated marginal means of VAS/back pain (p = 0.001) and ODI (p = 0.006) beginning at 3 months and continuing up to 1 year of follow-up. In conclusion,  LUFOS has been devised as a new practical and surgically oriented grading system based on simple key parameters from non-invasive preoperative imaging exams (magnetic resonance imaging/MRI and bone scan/99mTc scintigraphy) which has been shown to be highly predictive of surgical outcomes of patients undergoing lumbar fusion for treatment for refractory chronic axial LBP.

Pathophysiology of regression of synovial cysts of the lumbar spine: the 'anti-inflammatory hypothesis'.

The term 'synovial cysts' of the lumbar spine refers to cysts that arise from the zygapophyseal joint capsule of the lumbar spine. Although several cases of regression of lumbar spine synovial cysts after oral anti-inflammatory therapy as well as local steroid injection have already been reported in the literature, no study up to now has addressed the role of 'inflammation suppression' in the regression of such lesions. In fact most of the previous studies have regarded 'spontaneous rupture' as well as 'instability resolution' as the most probable explanations for such phenomenon. In this article the authors review the current experimental data about the role of cytokines and inflammation in the development of synovial cysts of the lumbar spine. Additionally with basis on both our clinical experience of regression of a synovial cyst after conservative treatment with a non-steroidal anti-inflammatory drug (Cox-2 inhibitor) as well as on the experimental data supporting the multi-factorial effects of such drugs on the lumbar facet joints, the authors hypothesize that inhibition of inflammation might play a significant role in the pathophysiology of lumbar spine synovial cysts' regression.

Recurrence-free chronic subdural hematomas: a retrospective analysis of the instillation of tissue plasminogen activator in addition to twist drill or burr hole drainage in the treatment of chronic subdural hematomas.

OBJECTIVE: To evaluate whether increasing the volume drained from chronic subdural hematomas (SDHs) via either twist drill drainage (TDD) or burr hole drainage (BHD) followed by instillation of tissue plasminogen activator (tPA) is more efficacious than simple drainage alone. METHODS: Patients admitted over the course of 42 months (2007-2010) to a single institution for treatment of chronic SDH were retrospectively evaluated. RESULTS: There were 139 patients treated for chronic SDH; 54 patients were treated with BHD alone, 3 were treated with tPA after BHD, 85 were treated with TDD alone, and 12 were treated with tPA after TDD. Follow-up examinations were performed 1 month after treatment in 13 of 15 patients treated with tPA and 93 of 124 patients treated without tPA. Patients treated with tPA had a significantly lower rate of recurrence than patients treated without tPA (P=0.041). Patients treated with BHD had a recurrence rate of 11.8%, whereas patients treated with BHD and tPA had 0% recurrence. Patients treated with TDD had a recurrence rate of 30%, whereas patients treated with TDD and tPA had 0% recurrence. Without tPA, BHD was found to be a significantly better treatment than TDD (P=0.016). Mean drainage for TDD with tPA was 427.33 mL. There were no complications related to the administration of tPA. CONCLUSIONS: This study adds another therapeutic option for patients with chronic SDH requiring treatment. In this retrospective study, the addition of tPA increased the volume of hematoma drained and significantly reduced the incidence of recurrence requiring further intervention regardless of cranial access route. No complications occurred related directly or indirectly to the administration of tPA. Further study of this technique is warranted.

Symptomatic occipitocervical paracondylar process.

A paracondylar process is a bony exostosis that arises from the skull base lateral to the occipital condyle and extends inferiorly toward the transverse process of the atlas. This congenital anomaly can vary in size from a small protuberance to an elongated process articulating with an epitransverse process arising from C-1. Typically, a paracondylar process is an incidental finding described in anatomical studies. The authors report on a patient with a symptomatic paracondylar process articulating with an epitransverse process that caused occipitocervical pain. Resection of the paracondylar and epitransverse processes completely relieved the patient's pain.

Treatment of large segmental bone defects with reamer-irrigator-aspirator bone graft: technique and case series.

Treatment of large segmental defects using conventional autogenous iliac crest bone graft can be limited by volume of cancellous bone and donor site morbidity. The reamer-irrigator-aspirator (RIA) technique allows access to a large volume of cancellous bone graft containing growth factors with potency equal to or greater than autograft material from the iliac crest. The purpose of this study was to evaluate the effectiveness of RIA-harvested autogenous bone graft for treating large segmental defects of long bones.

Comparison of low back fusion techniques: transforaminal lumbar interbody fusion (TLIF) or posterior lumbar interbody fusion (PLIF) approaches.

The authors review and compare posterior lumbar interbody fusion (PLIF) with transforaminal lumbar interbody fusion (TLIF). A review of the literature is performed wherein the history, indications for surgery, surgical procedures with their respective biomechanical advantages, potential complications, and grafting substances are presented. Along with the technical advancements and improvements in grafting substances, the indications and use of PLIF and TLIF have increased. The rate of arthrodesis has been shown to increase given placement of bone graft along the weight-bearing axis. The fusion rate across the disc space is further enhanced with the placement of posterior pedicle screw-rod constructs and the application of an osteoinductive material. The chief advantages of the TLIF procedure compared with the PLIF procedure included a decrease in potential neurological injury, improvement in lordotic alignment given graft placement within the anterior column, and preservation of posterior column integrity through minimizing lamina, facet, and pars dissection.

The cervical end of an occipitocervical fusion: a biomechanical evaluation of 3 constructs. Laboratory investigation.

OBJECT: Stabilization with rigid screw/rod fixation is the treatment of choice for craniocervical disorders requiring operative stabilization. The authors compare the relative immediate stiffness for occipital plate fixation in concordance with transarticular screw fixation (TASF), C-1 lateral mass and C-2 pars screw (C1L-C2P), and C-1 lateral mass and C-2 laminar screw (C1L-C2L) constructs, with and without a cross-link. METHODS: Ten intact human cadaveric spines (Oc-C4) were prepared and mounted in a 7-axis spine simulator. Each specimen was precycled and then tested in the intact state for flexion/extension, lateral bending, and axial rotation. Motion was tracked using the OptoTRAK 3D tracking system. The specimens were then destabilized and instrumented with an occipital plate and TASF. The spine was tested with and without the addition of a cross-link. The C1L-C2P and C1L-C2L constructs were similarly tested. RESULTS: All constructs demonstrated a significant increase in stiffness after instrumentation. The C1L-C2P construct was equivalent to the TASF in all moments. The C1L-C2L was significantly weaker than the C1L-C2P construct in all moments and significantly weaker than the TASF in lateral bending. The addition of a cross-link made no difference in the stiffness of any construct. CONCLUSIONS: All constructs provide significant immediate stability in the destabilized occipitocervical junction. Although the C1L-C2P construct performed best overall, the TASF was similar, and either one can be recommended. Decreased stiffness of the C1L-C2L construct might affect the success of clinical fusion. This construct should be reserved for cases in which anatomy precludes the use of the other two.

Use of resorbable collagen dural substitutes in the presence of cranial and spinal infections-report of 3 cases.

BACKGROUND: Various allografts, xenografts, and synthetic materials are used in neurosurgery to repair dural defects when primary suture closure is impossible and autologous grafts are inadequate or inaccessible. When used in contaminated or infected wounds, however, nonautologous grafts promote chronic colonization and recurring infection. Recently, several resorbable dural substitutes that are broken down biologically and replaced by autologous tissues have been introduced. These include type 1 collagen matrix (DuraGen, Integra LifeSciences, Plainsboro, NJ) and a collagen implant derived from bovine skin (Durepair, Medtronic, Inc, Minneapolis, Minn), which can be applied as sutured or sutureless onlay grafts. The safety and efficacy of this material has not been reported in the setting of wound contamination or infection. CASE DESCRIPTIONS: We present 3 cases in which these new collagen dural substitutes were successfully used to close dural defects in the presence of wound contamination and infection. In one case, a lumbar dural defect was closed with DuraGen in the presence of a subdural empyema. In the second case, maceration of the cranial dura mater from extensive compound depressed skull fractures was repaired with DuraGen in the presence of a subgaleal abscess. In the third case, a large dural defect in the setting of frontal osteomyelitis was successfully closed with sutured Durepair. In all cases appropriate antibiotic coverage was provided for the infection, and the tissues healed with excellent biologic incorporation and without evidence of further infection. CONCLUSIONS: Resorbable collagen dural grafts appear to be effective alternatives to either primary dural closure or the use of autologous-harvested tissue grafts in the setting of grossly contaminated or infected wounds.

Vertebroplasty and kyphoplasty: a comparative review of efficacy and adverse events.

Vertebroplasty and kyphoplasty have become common surgical techniques for the treatment of vertebral compression fractures. Vertebroplasty involves the percutaneous injection of bone cement into the cancellous bone of a vertebral body with the goals of pain alleviation and preventing further loss of vertebral body height. Kyphoplasty utilizes an inflatable balloon to create a cavity for the cement with the additional potential goals of restoring height and reducing kyphosis. Vertebroplasty and kyphoplasty are effective treatment options for the reduction of pain associated with vertebral body compression fractures. Biomechanical studies demonstrate that kyphoplasty is initially superior for increasing vertebral body height and reducing kyphosis, but these gains are lost with repetitive loading. Complications secondary to extravasation of cement include compression of neural elements and venous embolism. These complications are rare but more common with vertebroplasty. Vertebroplasty and kyphoplasty are both safe and effective procedures for the treatment of vertebral body compression fractures.

Pigmented villonodular synovitis associated with pathological fracture of the odontoid and atlantoaxial instability. Case report and review of the literature.

Pigmented villonodular synovitis (PVNS) is a proliferative disorder of the synovium with a predisposition for the appendicular skeleton. Rarely PVNS can arise from the spine, where this disorder usually presents with localized or radicular pain secondary to involvement of the posterior elements. The authors report the case of an 82-year-old woman who presented with long-standing neck pain and acute upper-extremity numbness and weakness. Computed tomography imaging revealed a mixed sclerotic and lucent lesion affecting the dens and right lateral mass of C-2. There was also a pathological fracture at the base of the dens with 8 mm of anterior dens displacement. Magnetic resonance imaging demonstrated a diffusely infiltrative process that was nonenhancing. Because of instability, the patient underwent transarticular screw fixation, and a biopsy of the lesion was also performed at this time. Histopathological analysis was consistent with a diagnosis of PVNS. To the authors' knowledge, this is the first report of PVNS involving the C-2 vertebra or causing a pathological fracture.

Volar versus dorsal fixed-angle fixation of dorsally unstable extra-articular distal radius fractures: a biomechanic study.

PURPOSE: To evaluate and compare the biomechanic rigidity and strength of 3 fixed-angle plates used to treat extra-articular distal radius fractures that are dorsally unstable. Volar fixed-angle plates were compared with a dorsal fixed-angle nail plate. METHODS: Three plate constructs were tested: the dorsal nail plate (DNP), distal volar radius (DVR) plate, and locking compression plate (LCP) volar distal radius plate. With anatomic, third-generation, artificial composite radii, dorsally unstable extra-articular distal radius fracture models were made by cutting a wedge osteotomy with an 8-mm dorsal gap 1 cm from the articular surface. These models were then fixed with the 3 implants by the method recommended by the manufacturer. The proximal radii of each specimen were attached to the base of a materials testing machine with a probe centered at the radial side of the lunate fossa. The specimens were loaded at a constant rate to failure under axial compression. Load and displacement were plotted graphically, and the resulting rigidities and strengths of each plate were assessed statistically. RESULTS: The DVR group had significantly greater stiffness than the LCP group. The DVR group had significantly higher maximum loads than both the DNP and LCP groups. There were no significant differences in yield loads. Both the DNP and DVR groups had significantly less displacement at yield than the LCP group. CONCLUSIONS: These 3 groups had similar yield loads. However, the LCP was less stiff than the DVR and had more displacement at yield than both the DVR and DNP. The yield load of all 3 implants was much higher than previously described loads for active wrist and finger motion.

Apoptosis suppression by somatic cell transfer of Bcl-2 promotes Sonic hedgehog-dependent medulloblastoma formation in mice.

Medulloblastomas are malignant brain tumors that arise in the cerebellum in children. Aberrant activation of the Sonic hedgehog (Shh) signaling pathway, which normally stimulates proliferation of granule neuron precursors (GNP) during cerebellar development, induces tumors in mice that closely mimic human medulloblastomas. Shh-dependent medulloblastoma formation is enhanced by hyperactive insulin-like growth factor (IGF) signaling and ectopic expression of Myc oncogenes. This enhanced tumorigenesis stems from the sensitivity of GNPs to IGF and Myc levels in regulating proliferation. An emerging theme in cancer research is that oncogene-induced cell proliferation cannot initiate neoplastic transformation unless cellular programs that mediate apoptosis are disabled. Here, we report a high frequency of medulloblastoma formation in mice after postnatal overexpression of the antiapoptotic protein Bcl-2 in cooperation with Shh. Ectopic expression of Bcl-2 alone or in combination with N-Myc did not induce tumors, indicating that Shh has essential transforming functions in GNPs not supplied by the mitogenic stimulus of N-Myc combined with a strong antiapoptotic signal provided by Bcl-2. Expression of endogenous Bcl-2 was not up-regulated in Shh-induced tumors. Instead, elevated levels of phosphorylated Akt were found, suggesting that activated phosphatidylinositol 3-kinase signaling is one intrinsic mechanism for suppressing apoptosis in Shh-dependent medulloblastomas. Thus, blockade of apoptosis cooperates with Shh-stimulated proliferation to transform GNPs and induce aggressive medulloblastomas. These findings provide insights into the molecular signals that initiate medulloblastoma formation and they support the importance of blocking apoptosis in carcinogenesis.

Glutaric aciduria type 1 presenting as bilateral subdural hematomas mimicking nonaccidental trauma. Case report and review of the literature.

Glutaric aciduria type 1 (GA1) is a rare neurometabolic disorder with characteristic neuroimaging and clinicopathological features. The authors describe a case of GA1 in a 7-month-old girl presenting with macrocephaly and bilateral subdural hematomas (SDHs) who was initially evaluated for nonaccidental trauma (NAT). Bilateral subdural drains were placed because of significant mass effect from the chronic SDHs, with subsequent neurological and neuroimaging-documented improvement. Clinical and neuroimaging findings led to further laboratory investigation to confirm the diagnosis of GA1, after which a specialized low-protein diet was initiated. After a thorough investigation, NAT was ruled out. At the follow-up examination, the patient experienced improvement in her symptoms and resolution of the bilateral subdural collections. The presence of bilateral SDHs in an infant raises the suspicion of NAT and presents a difficult diagnostic challenge because of the legal and social implications. Glutaric aciduria type 1 should be considered in the differential diagnosis of bilateral SDHs, and an evaluation should be performed. The authors review the clinical manifestations, diagnosis, medical and surgical management, and specific considerations regarding GA1, including misdiagnosis of NAT.

Cervical catheter tip placement for intrathecal baclofen administration.

OBJECTIVE: Intrathecal baclofen can reduce congenital and posttraumatic spasticity. Traditionally, the catheter tip for baclofen delivery is placed in a low thoracic position, which can result in a lumbar-to-cisternal cerebrospinal fluid baclofen concentration gradient. We investigated whether more rostral catheter placement was technically feasible, safe, and able to control upper extremity spasticity. METHODS: The records of 48 patients with a baclofen pump were reviewed retrospectively to evaluate the safety and efficacy of cervically placed intrathecal catheters for baclofen administration. Twenty-three patients had a catheter located in a cervical position and 25 had a catheter in a thoracic position (control group). Complications, including baclofen overdose, mechanical failures, and infections, were noted. Pre- and postoperative Ashworth scores were determined by a physical therapist using a standardized protocol. RESULTS: The mean duration of the follow-up period was 10 months. The groups were not significantly different in patient age, baclofen dose, or duration of follow-up, but differed somewhat in the causes of spasticity. For patients with a cervical catheter tip position, upper extremity Ashworth scores decreased significantly from 4.0 +/- 0.8 (standard deviation) preoperatively to 3.0 +/- 0.9 postoperatively (P = 0.003). In both groups, lower extremity spasticity was significantly reduced. Postoperatively, one patient with a cervical catheter developed aspiration pneumonia, possibly because of sedation. Other complications included hardware infections, mechanical malfunctions, and pseudomeningoceles. CONCLUSION: In this series, placement of intrathecal baclofen catheters in the cervical region resulted in equal control of spasticity in the upper and lower extremities and did not increase complications related to the catheter position.

Variations of disseminated choroid plexus papilloma: 2 case reports and a review of the literature.

BACKGROUND: Choroid plexus papillomas are typically considered benign lesions, but histology is not always predictive of their behavior. These tumors can metastasize anywhere along the neuraxis and may be intraventricular, subarachnoid, or intraparenchymal. We present 2 cases that illustrate the wide diversity with which choroid plexus papillomas can disseminate. CASE DESCRIPTIONS: The patient described in case 1 had a primary fourth ventricular choroid plexus papilloma that produced diffuse cystic subarachnoid and leptomeningeal lesions. Patient 2 also had a primary fourth ventricular tumor but with subsequent suprasellar and spinal drop metastases. Patient 1 was treated with temozolomide, resulting in regression of symptoms including headache and dizziness. Patient 2 has been treated with several modalities, including radiation therapy and chemotherapy, with slowing of symptom progression. CONCLUSIONS: Variations of choroid plexus papilloma dissemination include intraventricular, subarachnoid, and leptomeningeal nodules or cystic lesions, and intraparenchymal locations. There is no consensus on the most effective treatment for choroid plexus papilloma metastases; surgical resection, chemotherapy, and radiation therapy may all yield benefits. The prognosis for patients with disseminated choroid plexus papilloma can range from prolonged stable disease and symptoms to death within months.

Development and rapid growth of a desmoid tumor in the surgical corridor after suboccipital craniotomy for recurrent low-grade astrocytoma.

Desmoid tumors are histologically benign but locally invasive tumors that can occur in the head and neck. We present the rare case of a desmoid tumor that occurred in the surgical corridor after suboccipital craniotomy for recurrent low-grade astrocytoma. A 30-year-old woman underwent a repeat suboccipital craniotomy for recurrent low-grade astrocytoma. A gross total resection was achieved. Nine months later, a firm, palpable mass was noted near the surgical scar. No new neurologic deficits were noted on exam. A magnetic resonance imaging scan demonstrated a homogeneously enhancing lesion superficial to the dural graft. Surgical resection of the lesion was performed through the original midline incision. The mass was resected en bloc. Histology demonstrated clear surgical margins and a tumor of low cellularity consistent with a desmoid tumor. Desmoid tumors should be considered in the differential diagnosis for superficial masses occurring in the surgical bed after posterior cervical surgery.

Inflammatory pseudotumor of the cavernous sinus and skull base.

Inflammatory pseudotumor is a non-neoplastic process of unknown etiology characterized by a proliferation of connective tissue with an inflammatory infiltrate. Intracranial inflammatory pseudotumors classically involve the cavernous sinus but can also occur in the supratentorial or infratentorial compartments and spinal canal. Symptoms are dependent on location, and, when present in the cavernous sinus, typically include cranial nerve palsies of those nerves in the cavernous sinus. These lesions are rapidly responsive to steroid therapy. Surgery is typically indicated for biopsy only, but complete resection may be justified for lesions outside the cavernous sinus.