Transabdominal motor evoked potential neuromonitoring of lumbosacral spine surgery.

BACKGROUND CONTEXT: Transcranial Motor Evoked Potentials (TcMEPs) can improve intraoperative detection of femoral plexus and nerve root injury during lumbosacral spine surgery. However, even under ideal conditions, TcMEPs are not completely free of false-positive alerts due to the immobilizing effect of general anesthetics, especially in the proximal musculature. The application of transcutaneous stimulation to activate ventral nerve roots directly at the level of the conus medularis (bypassing the brain and spinal cord) has emerged as a method to potentially monitor the motor component of the femoral plexus and lumbosacral nerves free from the blunting effects of general anesthesia. PURPOSE: To evaluate the reliability and efficacy of transabdominal motor evoked potentials (TaMEPs) compared to TcMEPs during lumbosacral spine procedures. DESIGN: We present the findings of a single-center 12-month retrospective experience of all lumbosacral spine surgeries utilizing multimodality intraoperative neuromonitoring (IONM) consisting of TcMEPs, TaMEPs, somatosensory evoked potentials (SSEPs), electromyography (EMG), and electroencephalography. PATIENT SAMPLE: Two hundred and twenty patients having one, or a combination of lumbosacral spine procedures, including anterior lumbar interbody fusion (ALIF), lateral lumbar interbody fusion (LLIF), posterior spinal fusion (PSF), and/or transforaminal lumbar interbody fusion (TLIF). OUTCOME MEASURES: Intraoperative neuromonitoring data was correlated to immediate post-operative neurologic examinations and chart review. METHODS: Baseline reliability, false positive rate, true positive rate, false negative rate, area under the curve at baseline and at alerts, and detection of pre-operative deficits of TcMEPs and TaMEPs were compared and analyzed for statistical significance. The relationship between transcutaneous stimulation voltage level and patient BMI was also examined. RESULTS: TaMEPs were significantly more reliable than TcMEPs in all muscles except abductor hallucis. Of the 27 false positive alerts, 24 were TcMEPs alone, and 3 were TaMEPs alone. Of the 19 true positives, none were detected by TcMEPs alone, 3 were detected by TaMEPs alone (TcMEPs were not present), and the remaining 16 true positives involved TaMEPs and TcMEPs. TaMEPs had a significantly larger area under the curve (AUC) at baseline than TcMEPs in all muscles except abductor hallucis. The percent decrease in TcMEP and TaMEP AUC during LLIF alerts was not significantly different. Both TcMEPs and TaMEPs reflected three pre-existing motor deficits. Patient BMI and TaMEP stimulation intensity were found to be moderately positively correlated. CONCLUSIONS: These findings demonstrate the high reliability and predictability of TaMEPs and the potential added value when TaMEPs are incorporated into multimodality IONM during lumbosacral spine surgery.

The utility of intraoperative neuromonitoring on simple posterior lumbar fusions-analysis of the National Inpatient Sample.

BACKGROUND: Several studies have demonstrated the utility of intraoperative neuromonitoring (IOM) including somatosensory evoked potentials (SSEPs), motor-evoked potentials (MEPs), and electromyography (EMG), in decreasing the risk of neurologic injury in spinal deformity procedures. However, there is limited evidence supporting the routine use of IOM in elective posterolateral lumbar fusion (PLF). METHODS: The National Inpatient Sample (NIS) was analyzed for the years 2012-2015 to identify patients undergoing elective PLF with (n=22,404) or without (n=111,168) IOM use. Statistical analyses were conducted to assess the impact of IOM on length of stay, total charges, and development of neurologic complications. These analyses controlled for age, gender, race, income percentile, primary expected payer, number of reported comorbidities, hospital teaching status, and hospital size. RESULTS: The overall use of IOM in elective PLFs was found to have increased from 14.6% in the year 2012 to 19.3% in 2015. The total charge in hospitalization cost for all patients who received IOM increased from $129,384.72 in 2012 to $146,427.79 in 2015. Overall, the total charge of hospitalization was 11% greater in the IOM group when compared to those patients that did not have IOM (P<0.001). IOM did not have a statistically significant impact on the likelihood of developing a neurological complication. CONCLUSIONS: While there may conceivably be benefits to the use of this technology in complex revision fusions or pathologies, we found no meaningful benefit of its application to single-level index PLF for degenerative spine disease.

A wireless spinal stimulation system for ventral activation of the rat cervical spinal cord.

Electrical stimulation of the cervical spinal cord is gaining traction as a therapy following spinal cord injury; however, it is difficult to target the cervical motor region in a rodent using a non-penetrating stimulus compared with direct placement of intraspinal wire electrodes. Penetrating wire electrodes have been explored in rodent and pig models and, while they have proven beneficial in the injured spinal cord, the negative aspects of spinal parenchymal penetration (e.g., gliosis, neural tissue damage, and obdurate inflammation) are of concern when considering therapeutic potential. We therefore designed a novel approach for epidural stimulation of the rat spinal cord using a wireless stimulation system and ventral electrode array. Our approach allowed for preservation of mobility following surgery and was suitable for long term stimulation strategies in awake, freely functioning animals. Further, electrophysiology mapping of the ventral spinal cord revealed the ventral approach was suitable to target muscle groups of the rat forelimb and, at a single electrode lead position, different stimulation protocols could be applied to achieve unique activation patterns of the muscles of the forelimb.

Intraspinal mesenchymal chondrosarcoma: An argument for aggressive local resection and adjuvant therapy based on review of the literature.

BACKGROUND: Mesenchymal chondrosarcoma is a rare cartilaginous neoplasm that typically involves the axial skeleton. Despite a well-circumscribed appearance, this tumor has a tendency to recur both locally and with distant metastases. CASE DESCRIPTION: A 17-year-old patient presented with numbness and paresthesias in the lower extremities attributed to a T10-T11 intradural extramedullary mesenchymal chondrosarcoma. The patient was treated with aggressive local resection and adjuvant therapy. Here, this case and present literature are appropriately reviewed. CONCLUSION: Although uncommon, intraspinal mesenchymal chondrosarcomas warrant both radical local resection and aggressive adjuvant therapy with chemoradiation to provide the greatest chance of progression-free survival.

Contemporary Management of Increased Intraoperative Intracranial Pressure: Evidence-Based Anesthetic and Surgical Review.

Increased intracranial pressure (ICP) is frequently encountered in the neurosurgical setting. A multitude of tactics exists to reduce ICP, ranging from patient position and medications to cerebrospinal fluid diversion and surgical decompression. A vast amount of literature has been published regarding ICP management in the critical care setting, but studies specifically tailored toward the management of intraoperative acute increases in ICP or brain bulk are lacking. Compartmentalizing the intracranial space into blood, brain tissue, and cerebrospinal fluid and understanding the numerous techniques available to affect these individual compartments can guide the surgical team to quickly identify increased brain bulk and respond appropriately. Rapidly instituting measures for brain relaxation in the operating room is essential in optimizing patient outcomes. Knowledge of the efficacy, rapidity, feasibility, and risks of the various available interventions can aid the team to properly tailor their approach to each individual patient. In this article, we present the first evidence-based review of intraoperative management of ICP and brain bulk.

Minimally Invasive Tubular Tethered Cord Release in the Pediatric Population.

BACKGROUND: Tethered cord syndrome (TCS) refers to a clinical constellation of signs and symptoms associated with tension in the spinal cord and associated with pathologies related to abnormally low-lying conus medullaris. As minimally invasive spinal operations have become more prevalent in the past decade, we applied expanding indications to selected intradural procedures, such as tethered cord release (TCR). We present the first series of minimally invasive muscle-sparing TCR in the pediatric population. METHODS: A retrospective review of the Texas Children's Hospital, Houston, neurosurgical database was conducted for patients who underwent TCR between 2010 and 2017. Charts were reviewed to determine the source of TCS and whether surgery was conducted in a minimally invasive fashion. To establish a cohort of control population, age-matched cases of open TCR were selected in the same. Exclusion criterion was non-fatty filum sources of TCS. The length of stay, operative time, estimated blood loss, and postoperative complications were recorded. RESULTS: Eleven patients underwent minimally invasive TCR. Mean age of the patients was 10.1 years. All patients underwent L4-5 tubular laminotomy and cord detethering by 2 pediatric neurosurgeons at Texas Children's Hospital. The average length of stay in the hospital was 2.6 days. The average operative time was 167 minutes and average estimated blood loss was 8.2 mL. Ten patients reported clinical improvement and 1 patient was lost to follow-up. CONCLUSIONS: Minimally invasive TCR is a safe and represents a viable alternative to the open approach with advantages such as minimal estimated blood loss, shortened length of stay, and postoperative pain control.

Creutzfeldt Cell Rich Glioblastoma: A Diagnostic Dilemma.

Differentiating demyelinating conditions from neoplastic conditions can pose a significant challenge. There are a number of reports in the literature of large ring-enhancing, space-occupying lesions that were initially considered neoplastic or infectious but, on further review, were deemed demyelinating. Creutzfeldt-Peters cells (CPC) are reactive astrocytes with fragmented nuclear inclusions that are routinely seen in multiple sclerosis (MS) and generally exclude the diagnosis of glioblastoma (GB). The patient is a 78-year-old man with a history of prostate cancer, which was treated with radiation therapy, who presented with altered mental status. A magnetic resonance imaging (MRI) scan of the brain revealed a 4.6 x 3.1 cm mass lesion in the right posterior temporal lobe with minimal mass effect and heterogeneous contrast enhancement. The patient underwent an open biopsy of the mass, which on histology was rich with Creutzfeldt-Peters cells. Frozen histology was unclear and full resection of the mass was delayed. A molecular and immunohistochemical analysis confirmed glioblastoma. The patient returned four weeks later for a subtotal resection of the tumor. The case presented demonstrates an example of a challenging diagnosis. Differentiating between demyelinating and neoplastic conditions is critical since the management and prognosis differ greatly. More importantly, we present a case of glioblastoma rich with Creutzfeldt-Peters cells, which has previously not been reported in the literature.

Diagnostic Dilemma: Cerebellopontine Angle Lipoma Versus Dermoid Cyst.

Both lipomas and dermoid cysts of the cerebellopontine angle are rare tumors. These tumors differ in their embryological origin but share similar features on imaging. Both of these congenital lesions can be found in the cerebellopontine angle (CPA), and symptomatic clinical presentation is dictated by the location of the lesion. This paper demonstrates a unique case in which a CPA lipoma was misidentified as a dermoid cyst, leading to surgical intervention. Further, the paper provides a literature review of CPA lipomas and dermoid cysts to aid readers in further differentiating between these two unique tumors.

Spinal Schwannoma and Meningioma Mimicking a Single Mass at the Craniocervical Junction Subsequent to Remote Radiation Therapy for Acne Vulgaris.

BACKGROUND: Schwannomas and meningiomas are relatively common tumors of the nervous system. They have been reported in the literature as existing concurrently as a single mass, but very rarely have they been shown to present at the craniocervical junction. CASE DESCRIPTION: We present a rare and interesting case of a patient previously treated with radiation therapy for acne vulgaris and who presented to us with a concurrent schwannoma and meningioma of the craniocervical junction mimicking a single mass. CONCLUSIONS: These tumors can be solitary or mixed masses, and are known to be associated with certain disease processes such as long-term sequelae of radiation therapy and neurofibromatosis type 2. The precise mechanism behind the formation of these tumors is unknown; however, molecular cues in the tumor microenvironment may play a role.

Multicenter retrospective evaluation of the validity of the Thoracolumbar Injury Classification and Severity Score system in children.

OBJECTIVE The Thoracolumbar Injury Classification and Severity Score (TLICS) system was developed to streamline injury assessment and guide surgical decision making. To the best of the authors' knowledge, external validation in the pediatric age group has not been undertaken prior to this report. METHODS This study evaluated the use of the TLICS in a large retrospective series of children and adolescents treated at 4 pediatric medical centers (Texas Children's Hospital, Children's Healthcare of Atlanta, Riley Children's Hospital, and Doernbecher Children's Hospital). A total of 147 patients treated for traumatic thoracic or lumbar spine trauma between February 1, 2002, and September 1, 2015, were included in this study. Clinical and radiographic data were evaluated. Injuries were classified using American Spinal Injury Association (ASIA) status, Denis classification, and TLICS. RESULTS A total of 102 patients (69%) were treated conservatively, and 45 patients (31%) were treated surgically. All patients but one in the conservative group were classified as ASIA E. In this group, 86/102 patients (84%) had Denis type compression injuries. The TLICS in the conservative group ranged from 1 to 10 (mean 1.6). Overall, 93% of patients matched TLICS conservative treatment recommendations (score ≤ 3). No patients crossed over to the surgical group in delayed fashion. In the surgical group, 26/45 (58%) were ASIA E, whereas 19/45 (42%) had neurological deficits (ASIA A, B, C, or D). One of 45 (2%) patients was classified with Denis type compression injuries; 25/45 (56%) were classified with Denis type burst injuries; 14/45 (31%) were classified with Denis type seat belt injuries; and 5/45 (11%) were classified with Denis type fracture-dislocation injuries. The TLICS ranged from 2 to 10 (mean 6.4). Eighty-two percent of patients matched TLICS surgical treatment recommendations (score ≥ 5). No patients crossed over to the conservative management group. Eight patients (8/147, 5%) had a calculated TLICS of 4, which meant they were candidates for surgery or conservative therapy by TLICS criteria. Excluding these patients, the degree of agreement between TLICS and surgeon decision was deemed to be very good (κ = 0.878). CONCLUSIONS The TLICS results and recommendations matched treatment in 96% of conservative group cases. In the surgical group, TLICS recommendations matched treatment in 93% of cases. The TLICS recommendations and surgeon decision making displayed very good concordance. The TLICS appears to be effective in the classification of thoracic and lumbar spine injuries and in guiding treatment in the pediatric age group.

Isolated, Transient, Pneumocephalus-Induced Oculomotor Neuropathy After Microvascular Decompression of the Trigeminal Nerve.

BACKGROUND: Pneumocephalus is a common radiographic finding after posterior fossa craniotomy. In contrast, cranial neuropathies related to pneumocephalus are extremely rare, with only a handful of previous reports. CASE DESCRIPTION: We present the rare case of a right partial oculomotor mononeuropathy occurring in a 26-year-old woman 4 hours after a microvascular decompression of her right trigeminal nerve. Postoperative imaging revealed pneumocephalus in the interpeduncular cisterns with an air bubble close to the cisternal segment of the right oculomotor nerve, trapped by a fetal right posterior cerebral artery. The patient was placed on 100% Fio2 (fraction of inspired oxygen) and encouraged to remain in the Trendelenburg position. She was discharged with only modest improvement in her pupil-involved partial oculomotor palsy, but she improved over the course of clinical follow-up and her deficit had completely resolved at 6 months. CONCLUSIONS: Cranial neuropathy secondary to pneumocephalus is a rare and usually self-limiting condition. Although high-concentration oxygen therapy hastens resolution of pneumocephalus, recovery from pneumocephalus-related neuropathies may take weeks to months. To properly treat pneumocephalus-induced cranial neuropathies, further studies into the mechanism of injury are needed.

Primary central nervous system vasculitis preceded by granulomatous hypophysitis: Case report with a review of the literature.

BACKGROUND: Primary central nervous system (CNS) vasculitis is an idiopathic inflammatory process that selectively affects CNS vasculature without a systemic inflammatory response, and causes luminal obstruction with resultant ischemia of recipient tissue. Its varying clinical symptoms and signs depend on the caliber of vessels involved and distribution and location of the affected structures. Granulomatous hypophysitis (GH) is an autoimmune inflammatory process typically affecting women, and usually presents with hypopituitarism, and at times, diabetes insipidus, and/or visual loss. Both entities are rare CNS diseases, which, to our knowledge, have never been previously reported in the same patient. CASE DESCRIPTION: We present a unique case of chronic progressive primary CNS vasculitis causing limbic encephalopathy in a 30-year-old male with only a history of medication-controlled hypertension. He initially presented 4 months prior with nonspecific neurological complaints and was found to have a homogenously enhancing and enlarged pituitary, which was biopsy proven to be GH. CONCLUSION: This rather unique presentation highlights the need to maintain a high index of suspicion for underlying PCNS vasculitis in a patient who does not fit the typical demographic for isolated GH.