Intraoperative monitoring for tethered cord surgery: an update

Intraoperative somatosensory evoked potential (SEP) monitoring: an updated position statement by the American Society of Neurophysiological Monitoring

Somatosensory evoked potentials (SEPs) are used to assess the functional status of somatosensory pathways during surgical procedures and can help protect patients' neurological integrity intraoperatively. This is a position statement on intraoperative SEP monitoring from the American Society of Neurophysiological Monitoring (ASNM) and updates prior ASNM position statements on SEPs from the years 2005 and 2010. This position statement is endorsed by ASNM and serves as an educational service to the neurophysiological community on the recommended use of SEPs as a neurophysiological monitoring tool. It presents the rationale for SEP utilization and its clinical applications. It also covers the relevant anatomy, technical methodology for setup and signal acquisition, signal interpretation, anesthesia and physiological considerations, and documentation and credentialing requirements to optimize SEP monitoring to aid in protecting the nervous system during surgery.

Intraoperative Monitoring of the External Urethral Sphincter Reflex: A Novel Adjunct to Bulbocavernosus Reflex Neuromonitoring for Protecting the Sacral Neural Pathways Responsible for Urination, Defecation and Sexual Function

PURPOSE

Intraoperative bulbocavernosus reflex neuromonitoring has been utilized to protect bowel, bladder, and sexual function, providing a continuous functional assessment of the somatic sacral nervous system during surgeries where it is at risk. Bulbocavernosus reflex data may also provide additional functional insight, including an evaluation for spinal shock, distinguishing upper versus lower motor neuron injury (conus vs. cauda syndromes) and prognosis for postoperative bowel and bladder function. Continuous intraoperative bulbocavernosus reflex monitoring has been utilized to provide the surgeon with an ongoing functional assessment of the anatomical elements involved in the S2-S4 mediated reflex arc including the conus, cauda equina and pudendal nerves. Intraoperative bulbocavernosus reflex monitoring typically includes the electrical activation of the dorsal nerves of the genitals to initiate the afferent component of the reflex, followed by recording the resulting muscle response using needle electromyography recordings from the external anal sphincter.

METHODS

Herein we describe a complementary and novel technique that includes recording electromyography responses from the external urethral sphincter to monitor the external urethral sphincter reflex. Specialized foley catheters embedded with recording electrodes have recently become commercially available that provide the ability to perform intraoperative external urethral sphincter muscle recordings.

RESULTS

We describe technical details and the potential utility of incorporating external urethral sphincter reflex recordings into existing sacral neuromonitoring paradigms to provide redundant yet complementary data streams.

CONCLUSIONS

We present two illustrative neurosurgical oncology cases to demonstrate the utility of the external urethral sphincter reflex technique in the setting of the necessary surgical sacrifice of sacral nerve roots.

The diagnostic accuracy of neuromonitoring for detecting postoperative bowel and bladder dysfunction in spinal oncology surgery: a case series

PURPOSE

Postoperative bowel and bladder dysfunction (BBD) poses a significant risk following surgery of the sacral spinal segments and sacral nerve roots, particularly in neuro-oncology cases. The need for more reliable neuromonitoring techniques to enhance the safety of spine surgery is evident.

METHODS

We conducted a case series comprising 60 procedures involving 56 patients, spanning from September 2022 to January 2024. We assessed the diagnostic accuracy of sacral reflexes (bulbocavernosus and external urethral sphincter reflexes) and compared them with transcranial motor evoked potentials (TCMEP) incorporating anal sphincter (AS) and external urethral sphincter (EUS) recordings, as well as spontaneous electromyography (s-EMG) with AS and EUS recordings.

RESULTS

Sacral reflexes demonstrated a specificity of 100% in predicting postoperative BBD, with a sensitivity of 73.33%. While sensitivity slightly decreased to 64.71% at the 1-month follow-up, it remained consistently high overall. TCMEP with AS/EUS recordings did not identify any instances of postoperative BBD, whereas s-EMG with AS/EUS recordings showed a sensitivity of 14.29% and a specificity of 97.14%.

CONCLUSION

Sacral reflex monitoring emerges as a robust adjunct to routine neuromonitoring, offering surgeons valuable predictive insights to potentially mitigate the occurrence of postoperative BBD.

Prognostication of the neurological outcome of tethered cord based on intraoperative neuromonitoring findings: how close can we get?

PURPOSE

To evaluate the correlation of intraoperative neuromonitoring (IONM) data in surgery for tethered cord syndrome (TCS) in children to the neurological outcome at 1-year follow-up.

METHODS

208 consecutive patients operated on for TCS, between January 2011 to February 2020, under electrophysiological monitoring in the Division of Paediatric Neurosurgery, AIMS, Kochi, India, were included. Their preoperative neurological, urological and orthopaedic status were compared with the postoperative status at 1 year follow-up.

RESULTS

Our study prospectively collected the IONM data and retrospectively correlated it to the children's neurological outcome on follow-up. Out of 208 children, 28% (n = 59/208) had motor, 35% (n = 73/208) had bladder and 26% (n = 54/208) had bowel disturbances. Postsurgery, at one-year follow-up, 91% (n = 52/57) of the patients who had motor deficits had improvement, 82.3% (n = 51/62) of patients who had bladder deficits showed an improvement, and 88.8% (n = 48/54) with bowel deficits showed improvement. The monitorability for motor and sphincter potentials were 99.4% and 89.3%, respectively. Except for four patients (3 with bladder and 1 with motor worsening), all the patients who were monitorable with no deficits remained intact except for four patients, all the patients who had deficits and were monitorable improved after detethering (at 1 year). Clinical worsening corresponded to those who had a drop in amplitude of baseline TcMEP (n = 4). 18 events showed an increase in amplitude compared to the baseline TcMEP. These patients improved clinically on follow-up (at 1 year).

CONCLUSIONS

IONM complements the preoperative clinical details in predicting immediate and long-term outcomes.

Ventral anchoring of the conus medullaris: a new surgical technique preventing the radiographic recurrence of retethering after surgery for tethered spinal cord

OBJECTIVE

Retethering is not an unusual operation for a congenital lumbosacral dysraphic spinal lesion. The present study aimed to assess a new surgical technique for preventing retethering.

SURGICAL TECHNIQUE

After untethering the spinal cord, the pia mater or scar tissue at the caudal end of the conus medullaris is anchored to the ventral dura mater loosely using 8-0 thread, and the dura mater is closed directly. This technique is called ventral anchoring.

RESULTS

Ventral anchoring was performed in 15 patients (aged 5 to 37 years old, average age: 12.1 years old) between 2014 and 2021. All but one patient showed improvement or stabilization of the preoperative symptoms. No complication directly related to the procedure was observed. Postoperative MRI demonstrated that the dorsal subarachnoid space was restored in 14 patients but was undetectable or absent in three patients on follow-up MRI. No patients have experienced a recurrence of the tethered cord syndrome during the follow-up period.

CONCLUSION

Ventral anchoring is effective for restoring the dorsal subarachnoid space after untethering the spinal cord. This preliminary study suggested that ventral anchoring has the potential to prevent the postoperative radiographic recurrence of tethered spinal cord in patients with a congenital lumbosacral dysraphic spinal lesion.

Surgery for spina bifida occulta: spinal lipoma and tethered spinal cord

The technical evolution of the surgery for spina bifida occulta (SBO) over the course of a half-century was reviewed with special foci placed on the spinal lipoma and tethered spinal cord. Looking back through history, SBO had been included in spina bifida (SB). Since the first surgery for spinal lipoma in the mid-nineteenth century, SBO has come to be recognized as an independent pathology in the early twentieth century. A half-century ago, the only option available for SB diagnosis was the plain X-ray, and pioneers of the time persevered in the field of surgery. The classification of spinal lipoma was first described in the early 1970s, and the concept of tethered spinal cord (TSC) was proposed in 1976. Surgical management of spinal lipoma with partial resection was the most widely practiced approach and was indicated only for symptomatic patients. After understanding TSC and tethered cord syndrome (TCS), more aggressive approaches became preferred. A PubMed search suggested that there was a dramatic increase of publications on the topic beginning around 1980. There have been immense academic achievements and technical evolutions since then. From the authors' viewpoint, landmark achievements in this field are listed as follows: (1) establishment of the concept of TSC and the understanding of TCS; (2) unraveling the process of secondary and junctional neurulation; (3) introduction of modern intraoperative neurophysiological mapping and monitoring (IONM) for surgery of spinal lipomas, especially the introduction of bulbocavernosus reflex (BCR) monitoring; (4) introduction of radical resection as a surgical technique; and (5) proposal of a new classification system of spinal lipomas based on embryonic stage. Understanding the embryonic background seems critical because different embryonic stages bring different clinical features and of course different spinal lipomas. Surgical indications and selection of surgical technique should be judged based on the background embryonic stage of the spinal lipoma. As time flows forward, technology continues to advance. Further accumulation of clinical experience and research will open the new horizon in the management of spinal lipomas and other SBO in the next half-century.

Intraoperative neurophysiology in pediatric neurosurgery: a historical perspective

INTRODUCTION

Intraoperative neurophysiology (ION) has been established over the past three decades as a valuable discipline to improve the safety of neurosurgical procedures with the main goal of reducing neurological morbidity. Neurosurgeons have substantially contributed to the development of this field not only by implementing the use and refinement of ION in the operating room but also by introducing novel techniques for both mapping and monitoring of neural pathways.

METHODS

This review provides a personal perspective on the evolution of ION in a variety of pediatric neurosurgical procedures: from brain tumor to brainstem surgery, from spinal cord tumor to tethered cord surgery.

RESULTS AND DISCUSSION

The contribution of pediatric neurosurgeons is highlighted showing how our discipline has played a crucial role in promoting ION at the turn of the century. Finally, a view on novel ION techniques and their potential implications for pediatric neurosurgery will provide insights into the future of ION, further supporting the view of a functional, rather than merely anatomical, approach to pediatric neurosurgery.

The role of intraoperative neuromonitoring in pygopagus separation: two-institution experience in Indonesia

INTRODUCTION

Pygopagus comprises 17% of all conjoined twin cases. Survival rate is higher compared to other variations of conjoined twins, but separation is a great challenge due to multiorgan involvement. Intraoperative neuromonitoring (IONM) used aims to aid operator in preserving as much function as possible.

CASE PRESENTATIONS

The authors reported 2 pairs of pygopagus separation. Intraoperatively, motor-evoked potential (MEP) and sensory-evoked potential (SEP) were used in all patients. Three patients survived in which all had transient motor deficits. Urinary retention was reported in one patient. One patient died 2 weeks after separation as twins only had one kidney which was spared for the healthier twin.

DISCUSSION

IONM was used to guide operator in dissecting, identify the ownership of the neural structures, and determine the safest point to separate in pygopagus separation. Despite the normal MEP and SEP recordings, transient motor weakness may still occur transiently. The motor tract development of children is achieved in adolescence, making MEP less accurate. However, the reliability of MEP increases when it is combined with SEP. Autonomic function monitoring such as bulbocavernosus reflex (BCR) could not be assessed due to the unavailability of the probe.

CONCLUSION

IONM can aid operator in pygopagus separation during determining the origins of the structure, dissecting, and cutting the neural structures. Normal MEP interpretations are still possible to correlate with transient deficits, but reliability can be improved with the use of SEP. In surgeries involving the lower spine level, BCR monitoring is recommended to avoid autonomic deficits.

Updates on Intraoperative Neurophysiology During Surgery for Spinal Dysraphism

Spinal dysraphism is a group of disorders resulting from an embryologic failure of spinal cord development which can lead to a radicular-medullary mechanical stretch that generates vascular compromise and hypoxic-ischemic damage to the nervous structures of the conus-cauda region.Thus, the clinical relevance of the different types of spinal dysraphism is related to the possible neurologic deficits resulting from spinal cord tethering. The clinical presentation is heterogenous: from asymptomatic to very compromised patients. The indications and the time of a detethering surgery are still subject of debate, although there is an agreement on the high standards of treatment that have to be offered by the surgery. Intraoperative neurophysiology (ION) contributes to the safety of tethered cord surgery in reducing the risks of iatrogenic neurological damages.

Transcranial electric stimulation motor evoked potentials for cervical spine intraoperative monitoring complications: systematic review and illustrative case of cardiac arrest

PURPOSE

We show a systematic review of known complications during intraoperative neuromonitoring (IONM) using transcranial electric stimulation motor evoked potentials (TES-MEP) on cervical spine surgery, which provides a summary of the main findings. A rare complication during this procedure, cardiac arrest by cardioinhibitory reflex, is also described.

METHODS

Findings of 523 scientific papers published from 1995 onwards were reviewed in the following databases: CENTRAL, Cochrane Library, Embase, Google Scholar, Ovid, LILACS, PubMed, and Web of Science. This study evaluated only complications on cervical spine surgery undergoing TES-MEP IONM.

RESULTS

The review of the literature yielded 13 studies on the complications of TES-MEP IONM, from which three were excluded. Five studies are case series; the rest are case reports. Overall, 169 complications on 167 patients were reported in a total of 38,915 patients, a global prevalence of 0.43%. The most common complication was tongue-bite in 129 cases, (76.3% of all complication events). Tongue-bite had a prevalence of 0.33% (CI 95%, 0.28-0.39%) in all patients on TES-MEP IONM. A relatively low prevalence of severe complications was found: cardiac-arrhythmia, bradycardia and seizure, the prevalence of this complications represents only one case in all the sample. Alongside, we report the occurrence of cardiac arrest attributable to TES-MEP IONM.

CONCLUSIONS

This systematic review shows that TES-MEP is a safe procedure with a very low prevalence of complications. To our best knowledge, asystole is reported for the first time as a complication during TES-MEP IONM.

Intraoperative Neuromonitoring for Pediatric Pelvic Tumors

Background

Tumors of the pre-sacral and sacral spaces are a rare occurrence in children. Total tumor excision is required due to the significant risk of relapse in the event of partial surgery, but the surgical procedure may lead to postoperative problems such as urinary, sexual, and anorectal dysfunctions. Intraoperative neuromonitoring (IONM) has gained popularity in recent years as a strategy for preventing the onset of neurologic impairments by combining several neurophysiological techniques. The aim of our study is to describe the experience of Bambino Gesù Children's Hospital in the use of IONM in pediatric pelvic surgery.

Materials and Methods

The data of patients treated for pelvic malignancies at Bambino Gesù Children's Hospital from 2015 to 2019 were retrospectively collected. All patients were assessed from a neurologic and neuro-urologic point of view at different time-points (before and immediately after surgery, after 6 months, and 1-year follow-up). They were all monitored during a surgical procedure using multimodal IONM including transcranial motor evoked potentials (TcMEP), triggered-EMG (t-EMG), pudendal somatosensory evoked potentials (PSSEP), and bulbocavernosus reflex (BCR).

Results

During the study period, ten children underwent pelvic tumor removal at our Institution. In all cases, intraoperative neurophysiological recordings were stable and feasible. The preservation of neurophysiological response at the same intensity during surgical procedures correlated with no new deficits for all neurophysiological techniques.

Discussion

Although the impact of the IONM on surgical strategies and clinical follow-up is unknown, this preliminary experience suggests that the appropriate use of several neurophysiological techniques can influence both the radicality of pelvic tumor removal and the neurological and urological outcome at clinical follow-up. Finally, because of the highly complex anatomy and inter-individual variances, this is especially useful in this type of surgery.

Long-term outcome following surgical treatment of posttraumatic tethered cord syndrome: a retrospective population-based cohort study

STUDY DESIGN

Retrospective population-based cohort study.

OBJECTIVE

To investigate the long-term outcome following surgery for posttraumatic spinal cord tethering (PSCT).

SETTING

Publicly funded tertiary care center.

METHODS

Patients surgically treated for PSCT between 2005-2020 were identified and included. No patients were excluded or lost to follow-up. Medical records and imaging data were retrospectively reviewed.

RESULTS

Seventeen patients were included. Median age was 52 (23-69) years and 7 (41%) were female. PSCT was diagnosed at a median of 5.0 (0.6-27) years after the initial trauma. Motor deficit was the most common neurological manifestation (71%), followed by sensory deficit (53%), spasticity (53%), pain (41%) and gait disturbance (24%). Median follow-up time was 5.1 (0.7-13) years. Fifteen patients (88%) showed satisfactory results following untethering, defined as improvement or halted progression of one or more of the presenting symptoms. Treatment goals were met for motor symptoms in 92%, sensory loss in 100%, spasticity in 100%, gait disturbance in 100% and pain in 86%. Statistically, a significant improvement in motor deficit (p = 0.031) and syrinx decrease (p = 0.004) was also seen. A postoperative complication occurred in four patients: three cases of cerebrospinal fluid leakage and one postoperative hematoma. Two patients showed a negative surgical outcome: 1 with increased neck pain and 1 with left arm weakness following the postoperative hematoma.

CONCLUSION

Surgical treatment of PSCT results in improved neurological function or halted neurological deterioration in the vast majority of patients.

Outcomes of cauda equina syndrome due to lumbar disc herniation after surgical management and the factors affecting it: a systematic review and meta-analysis of 22 studies with 852 cases

PURPOSE

This study aimed to investigate the long-term clinical outcomes after surgical decompression in cauda equina syndrome (CES) and see if any preoperative patient-related factors contributed to this outcome.

METHODS

A systematic literature search was conducted in the electronic databases of PubMed, Embase, Scopus, and Ovid. Data regarding outcome parameters from eligible studies were extracted. Meta-analysis was performed using a random-effect model.

RESULTS

A total of 852 patients (492 males and 360 females), with a mean age of 44.6 ± 5.5 years from 22 studies diagnosed with cauda equina syndrome and undergoing surgical decompression, were included in the meta-analysis; however, not all studies reported every outcome. The mean follow-up period was 39.2 months, with a minimum follow-up of 12 months in all included studies. Meta-analysis showed that on long-term follow-up, 43.3% [29.1, 57.5] (n=708) of patients had persistent bladder dysfunction. Persistent bowel dysfunction was observed in 31.1% [14.7, 47.6] (n=439) cases, sensory deficit in 53.3% [37.1, 69.6] (n=519), motor weakness in 38.4% [22.4, 54.4] (n=490), and sexual dysfunction in 40.1% [28.0, 52.1] (n=411). Decompression within 48 hours of the onset of symptoms was associated with a favourable outcome in terms of bladder function with 24.6% [1.6, 50.9] (n=75) patients having persistent dysfunction, whereas 50.3% [10.3, 90.4] (n=185) of patients in studies with a mean time to decompression after 48 hours had persistent bladder dysfunction. Other factors such as speed of onset and sex of the patients were not found to significantly impact long-term bladder outcomes.

CONCLUSION

The long-term outcomes of CES after decompression are enumerated. Decompression within 48 hours of the onset of symptoms appears to result in fewer patients with persistent bladder dysfunction. However, a randomized controlled trial is required to conclusively determine whether early decompression leads to better outcomes.

Intraoperative neurophysiological monitoring in paediatric neurosurgery

Intraoperative neurophysiological monitoring (IONM) is commonly used in various surgical procedures in adults, but with technological and anaesthetic advancements, its use has extended to the paediatric population. The use of IONM in children poses a unique set of challenges considering the anatomical and physiological differences in this group of patients. The use of IONM aids in the localization of neural structures and enables surgeons to preserve the functional neural structures leading to decreased incidence of postoperative neurological deficits and better patient outcomes. In this article, we review the use of IONM in paediatric patients undergoing various spinal and cranial neurosurgical procedures. We discuss the patient characteristics, type of surgeries, and technical and anaesthetic considerations about IONM in this population.

5-ALA fluorescence for intraoperative visualization of spinal ependymal tumors and identification of unexpected residual tumor tissue: experience in 31 patients

OBJECTIVE

Gross-total resection (GTR) is the treatment of choice in the majority of patients suffering from spinal ependymal tumors. In such tumors, the extent of resection (EOR) is considered the key factor for tumor recurrence and thus patient prognosis. However, incomplete resection is not uncommon and leads to increased risk of tumor recurrence. One important cause of incomplete resection is insufficient intraoperative visualization of tumor tissue as well as residual tumor tissue. Therefore, the authors investigated the value of 5-aminolevulinic acid (5-ALA)-induced fluorescence in a series of spinal ependymal tumors for improved tumor visualization.

METHODS

Adult patients who underwent preoperative 5-ALA administration and surgery for a spinal ependymal tumor were included in this study. For each tumor, a conventional white-light microsurgical resection was performed. Additionally, the fluorescence status (strong, vague, or no fluorescence) and fluorescence homogeneity (homogenous or inhomogeneous) of the spinal ependymal tumors were evaluated during surgery using a modified neurosurgical microscope. In intramedullary tumor cases with assumed GTR, the resection cavity was investigated for potential residual fluorescing foci under white-light microscopy. In cases with residual fluorescing foci, these areas were safely resected and the corresponding samples were histopathologically screened for the presence of tumor tissue.

RESULTS

In total, 31 spinal ependymal tumors, including 27 intramedullary tumors and 4 intradural extramedullary tumors, were included in this study. Visible fluorescence was observed in the majority of spinal ependymal tumors (n = 25, 81%). Of those, strong fluorescence was noted in 23 of these cases (92%), whereas vague fluorescence was present in 2 cases (8%). In contrast, no fluorescence was observed in the remaining 6 tumors (19%). Most ependymal tumors demonstrated an inhomogeneous fluorescence effect (17 of 25 cases, 68%). After assumed GTR in intramedullary tumors (n = 15), unexpected residual fluorescing foci within the resection cavity could be detected in 5 tumors (33%). These residual fluorescing foci histopathologically corresponded to residual tumor tissue in all cases.

CONCLUSIONS

This study indicates that 5-ALA fluorescence makes it possible to visualize the majority of spinal ependymal tumors during surgery. Unexpected residual tumor tissue could be detected with the assistance of 5-ALA fluorescence in approximately one-third of analyzed intramedullary tumors. Thus, 5-ALA fluorescence might be useful to increase the EOR, particularly in intramedullary ependymal tumors, in order to reduce the risk of tumor recurrence.

Early de-tethering: analysis of urological and clinical consequences in a series of 40 children

PURPOSE

Early de-tethering procedures are performed on spinal dysraphisms to prevent neuro-urological deterioration caused by growth. Partial lipoma removal may cause delayed deterioration by re-tethering, while complete removal may increase the risk of postoperative worsening. The present study evaluates the risk of postoperative deterioration and the protective potential of intraoperative neurophysiological monitoring (IOM), with a special reference to the conus lipomas treated with the radical approach.

METHODS

Forty toddlers (< 24 months) underwent complete perioperative neurological and urological assessment, including urodynamic study (UDS). The dysraphisms were subgrouped according to Pang's classification. IOM was applied in all patients: transcranial motor evoked potentials (tMep) combined with mapping were recorded in all cases while bulbocavernosus reflex (BCR) was evaluable just in 7 cases.

RESULTS

At preoperative evaluation, 11 children already had UDS impairment and 2 had motor disturbances before neurosurgery. At 1-month follow-up, preoperative motor disturbances were stable, 7/11 UDS alterations normalized, and the remaining 4 were stable. At 6-month follow-up, all motor deficits and 8/11 preoperative UDS alterations had improved. Unfortunately, 7 children with previously normal UDS experienced a new impairment after surgery: 2/7 normalized while 5/7 did not recover. This postoperative permanent urodynamic impairment occurred in 4 chaotic lipoma (CLchaos) and in one terminal myelocystocele (TMC) that means a surgical deterioration rate of 22% for the high risk cases.

CONCLUSIONS

This small highly selected series confirms that early de-tethering may stop or revert the spontaneous neuro-urological deterioration: in fact, preoperative UDS impairment was frequent (27.5%) and improved in all the low surgical risk cases (limited dorsal myeloschisis, filar, transitional and dorsal lipomas). On the contrary, in CLchaos and TMC, early de-tethering was unable to revert preoperative UDS impairment, and radical surgery carried a high risk of new neuro-urological deterioration directly caused by the operation. In our experience, IOM had a protective role for motor functions, while it was less effective for the neuro-urological ones, probably due to the anesthesiology regimens applied. In conclusion, among the dysraphisms, CLchoas proved to be the worst enemy that often camouflages at MRI. Affording it without all possible IOM weapons carries a high risk to harm the patient.

Filum terminale lipomas-the role of intraoperative neuromonitoring

BACKGROUND

Filum terminale lipomas (FTL) represent a sub-type of spinal lipomas, where there is fatty infiltration of the filum. It becomes a surgical entity when it manifests as clinical or radiological tethered cord syndrome. Intraoperative neuromonitoring (IONM) has been suggested as a valuable tool in children for tethered cord surgeries. FTL is distinct and cannot be compared with complex tethered cord syndrome (TCS). Untethering an FTL is a relatively straightforward microsurgical exercise, usually based on anatomical findings. Neurological morbidity in FTL untethering is extremely low. The necessity of IONM in FTL has not been evaluated. The objective of this study was to identify the role of IONM in untethering an FTL METHODS: Available electronic data and case files were interrogated to identify children (0-18 years) who underwent an untethering of FTL between 2008 and 2019. We had a shift in our policy and tried to use IONM as often as possible in all tethered cord surgery from 2014. All children were categorised under 'IONM implemented' or 'no IONM' group. Outcomes analysed were as follows: (1) Clinical status on short-term and long-term follow-up, (2) alteration of surgical course by IONM and (3) complications specifically associated with IONM RESULTS: Among 80 children included in this study, IONM was implemented in 37 children and 43 children underwent untethering without IONM. 32.5% of children were 'syndromic'. Seventy-five percent of children were under age 3 years during surgery. Both groups (No IONM vs. IONM implemented) were well matched in most variables. Majority of 'no IONM' surgeries were performed prior to 2014. There was no neurological morbidity in the entire cohort. Mean duration of follow-up was 49.10 (± 33.67) months. Short-term and long-term clinical status remained stable in both cohorts. In 16 children, the filum was stimulated. Based on our protocol, majority had a negative response. One child showed a positive response, contradicted by thorough microscopic inspection. Despite a positive response, the filum was untethered. IONM was not associated with any complication in this study.

CONCLUSION

FTL untethering is an inherently low-risk microsurgery in experienced hands with rarely reported neurological morbidity. IONM may not be required for all FTL and may be used more judiciously.

Intraoperative Neuromonitoring for Tethered Cord Surgery in Infants: Challenges and Outcome

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of intraoperative neuromonitoring (IONM) in surgery for tethered cord in infants.

MATERIALS AND METHODS

The study included 87 infants who underwent surgery for closed spinal dysraphism under IONM. Their preoperative neurological and urological statuses were compared with postoperative status clinically. The study design was prospective, and the study's duration was from January 2011 to February 2020. IONM was performed (TcMEP and direct mapping) with an Xltek Protektor 32 IOM system, Natus Neurology/medical Inc., Middleton, USA. Statistical analysis in the form of χ2 is conducted using SPSS.

RESULTS

Overall, among 87 patients, clinical improvement was seen in 28 (28/29) patients with motor deficits, 17 (17/24) with bladder deficits, and 18 (18/24) with bowel deficits. The monitorability for motor and sphincter was 97.3% and 90.7%, respectively. The sensitivity of IONM in predicting new motor deficit was 100%, whereas the specificity was 100%. The negative predictive value of predicting motor deficit was 100%, with a diagnostic accuracy of 100%. There were no complications in this cohort related to the IONM.

CONCLUSIONS

The study has highlighted that the use of IONM is sensitive in identifying motor injury in infants with reliable outcome correlation. Assessment, monitoring, and outcome correlation of bladder and sphincteric functions are a challenge in this cohort.

Intraoperative Neurophysiology Monitoring for Spinal Dysraphism

Spinal dysraphism often causes neurological impairment from direct involvement of lesions or from cord tethering. The conus medullaris and lumbosacral roots are most vulnerable. Surgical intervention such as untethering surgery is indicated to minimize or prevent further neurological deficits. Because untethering surgery itself imposes risk of neural injury, intraoperative neurophysiological monitoring (IONM) is indicated to help surgeons to be guided during surgery and to improve functional outcome. Monitoring of electromyography (EMG), motor evoked potential, and bulbocavernosus reflex (BCR) is essential modalities in IONM for untethering. Sensory evoked potential can be also employed to further interpretation. In specific, free-running EMG and triggered EMG is of most utility to identify lumbosacral roots within the field of surgery and filum terminale or non-functioning cord can be also confirmed by absence of responses at higher intensity of stimulation. The sacral nervous system should be vigilantly monitored as pathophysiology of tethered cord syndrome affects the sacral function most and earliest. BCR monitoring can be readily applicable for sacral monitoring and has been shown to be useful for prediction of postoperative sacral dysfunction. Further research is guaranteed because current IONM methodology in spinal dysraphism is still deficient of quantitative and objective evaluation and fails to directly measure the sacral autonomic nervous system.

Current status and treatment modalities in metastases to the pituitary: a systematic review

BACKGROUND

Metastases to the pituitary (MP) are uncommon, accounting for 0.4% of intracranial metastases. Through advances in neuroimaging and oncological therapies, patients with metastatic cancers are living longer and MP may be more frequent. This review aimed to investigate clinical and oncological features, treatment modalities and their effect on survival.

METHODS

A systematic review was performed according to PRISMA recommendations. All cases of MP were included, excepted primary pituitary neoplasms and autopsy reports. Descriptive and survival analyses were then conducted.

RESULTS

The search identified 2143 records, of which 157 were included. A total of 657 cases of MP were reported, including 334 females (50.8%). The mean ± standard deviation age was 59.1 ± 11.9 years. Lung cancer was the most frequent primary site (31.0%), followed by breast (26.2%) and kidney cancers (8.1%). Median survival from MP diagnosis was 14 months. Overall survival was significantly different between lung, breast and kidney cancers (P < .0001). Survival was impacted by radiotherapy (hazard ratio (HR) 0.49; 95% confidence interval (CI) 0.35-0.67; P < .0001) and chemotherapy (HR 0.58; 95% CI 0.36-0.92; P = .013) but not by surgery. Stereotactic radiotherapy tended to improve survival over conventional radiotherapy (HR 0.66; 95% CI 0.39-1.12; P = .065). Patients from recent studies (≥ 2010) had longer survival than others (HR 1.36; 95% CI 1.05-1.76; P = .0019).

CONCLUSION

This systematic review based on 657 cases helped to better identify clinical features, oncological characteristics and the effect of current therapies in patients with MP. Survival patterns were conditioned upon primary cancer histologies, the use of local radiotherapy and systemic chemotherapy, but not by surgery.

Intraoperative neurophysiological monitoring of the bulbocavernosus reflex during surgery for conus spinal lipoma: what are the warning criteria?

OBJECTIVE

Despite the surge in the intraoperative use of the bulbocavernosus reflex (BCR) during lumbosacral surgeries, there are as yet no widely accepted BCR warning criteria for use with intraoperative neurophysiological monitoring (IONM). The author's aim was to find clinically acceptable warning criteria for use in IONM of the BCR.

METHODS

Records of IONM of the BCR in 164 operations in 163 patients (median age 5 months) with a conus spinal lipoma who underwent surgery between August 2002 and May 2016 were retrospectively analyzed. The outcomes of IONM of the BCR were grouped by the residual amplitude at the end of surgery: group 1, ≥ 50%; group 2, 25%-50% (including the lower bound, but not the upper); and group 3, < 25%. Cases in which the BCR was lost were separately assessed as a subgroup of group 3. The postoperative urinary complication rate was used to verify the warning criteria zones.

RESULTS

The BCR could be monitored in 149 surgeries (90.9%). There were 118 surgeries (79.2%) in group 1, 18 (12.1%) in group 2, and 13 (8.7%) in group 3. Two surgeries (11.1%) in group 2 and 6 (46.2%) in group 3 resulted in urinary complications. In the group 3 subgroup (lost BCR), all 5 surgeries resulted in urinary complications. The cutoff value of the BCR amplitude reduction was placed between groups 1 and 2 (zone 1: cutoff 50%), groups 2 and 3 (zone 2: cutoff 25%), and group 3 and its subgroup (zone 3: cutoff zero, present or lost). In zone 1, the positive predictive value (PPV) was 25.8% and the negative predictive value (NPV) was 100%. In zone 2, the PPV was 53.8% and the NPV 98.5%. In zone 3, the PPV was 100% and the NPV 97.9%. The PPV was highest in zone 3. The NPV was highest in zone 1, but its PPV was low (25.8%).

CONCLUSIONS

The "lost or remained" criterion of BCR amplitude (zone 3: cutoff zero) can be used as a predictor of postoperative urinary function. As a warning criterion, the cutoff value of the BCR amplitude reduction at 75% (zone 2) may be used. This preliminary clinical report on the warning criteria for the BCR may contribute to improving the safety of surgery for conus spinal lipoma.

Sellar Metastasis of Cervical Adenocarcinoma

Background

Pituitary metastasis of cervical adenocarcinoma is an exceedingly rare phenomenon.

Case Description

The authors present a case of a 66-year-old female with cervical adenocarcinoma who was discovered to have a rapidly growing intrasellar mass in the work-up of adrenal insufficiency and hypothyroidism. The patient underwent subsequent endoscopic endonasal subtotal resection of the mass. Histopathological analysis of the resected lesion demonstrated features consistent with metastatic mucinous adenocarcinoma of the cervix. While initially neurologically asymptomatic following surgery, the patient developed an oculomotor nerve palsy several weeks following surgical debulking, at which time neuroimaging revealed marked regrowth and suprasellar extension of the metastatic lesion.

Conclusions

While metastatic cervical adenocarcinoma to the sella is rare, it should be considered in the differential based on the history of the patient.

Predictive value of intraoperative bulbocavernosus reflex during untethering surgery for post-operative voiding function

OBJECTIVE

To evaluate the clinical significance of intraoperative bulbocavernosus reflex (BCR) during untethering surgery in predicting post-operative voiding function.

METHODS

We conducted a retrospective review of pediatric patients who underwent untethering surgery with available intraoperative baseline BCR. BCR response during surgery was classified into loss or maintenance. Post-operative voiding function was determined as worsened or maintained based on history, postvoid residual urine measurement, and urodynamic study (UDS). Data regarding demographics, diagnosis, pre-operative voiding difficulty, re-untethering, syrinx, and abnormalities in electromyography were collected for analysis.

RESULTS

We included 106 patients, with a mean age of 3.3 years, and 49 patients were male. BCR was lost in 15 patients during surgery and voiding function worsened in 14 patients after surgery. Lumbosacral lipoma was the most common diagnosis, and 16 patients were diagnosed with lipomyelomeningocele (LMMC). The sensitivity and specificity of intraoperative BCR for post-operative worsening of voiding function were 35.7%, and 88.5% at 6 months, respectively. The diagnosis of LMMC was statistically significant in a logistic regression analysis. The specificity of BCR at 6 months in patients with diagnosis other than LMMC was 93.4%, and intraoperative BCR was significant in a logistic regression analysis.

CONCLUSIONS

Intraoperative BCR during untethering could predict bladder function 6 months post-operatively with high specificity (88.5%), particularly in cases other than LMMC (93.4%), indicating that voiding function deterioration will not occur if intraoperative BCR is preserved.

SIGNIFICANCE

Intraoperative BCR during untethering surgery is a useful tool to predict post-operative voiding outcome.

Using subdural strip electrodes to define functional sensory nerves and the most inferior functional portion of the conus medullaris during detethering surgeries for tethered cord syndrome: a pilot study

OBJECTIVE

The aim of this study was to investigate the feasibility of using subdural strip electrodes, placed just rostral to the surgical field, to record sensory evoked potentials (SEPs) from the lumbosacral sensory nerves and define the most inferior functional portion of the conus medullaris during detethering surgery for spinal dysraphism and/or tethered cord syndrome (TCS).

METHODS

Six patients, 2 boys and 4 girls, aged 0.5 to 16 years, were enrolled in this study. One patient had lipomyelomeningocele-related, 4 had myelomeningocele-related, and 1 had diastematomyelia and lipomyelomeningocele-related TCS. In addition to the routine preparations that are needed for performing functional mapping and monitoring during surgery for spinal dysraphism and TCS, the patients had a 1 × 4 strip of electrodes placed rostral to the surgical field, where it was secured by a surgeon after opening the dura. With the patient under total intravenous anesthesia, the sensory nerves and conus medullaris were stimulated with a concentric bipolar electrode over the surgical field while SEPs were recorded with the strip electrodes to identify any possible sensory roots with remaining function and the most inferior functional portion of the conus medullaris.

RESULTS

The SEP amplitudes that were recorded with the subdural strip electrodes ranged from 4 to 400 μV, and the responses to sensory nerve stimulation were frequently much larger than were those to conus stimulation. Use of the SEP recordings for sensory mapping along with the routine mapping and monitoring techniques allowed detethering to be completed such that none of the patients sustained any new functional deficit after surgery.

CONCLUSIONS

Recording SEPs from the functional sensory nerves and conus medullaris through subdural strip electrodes proved to be a feasible and valuable tool during detethering surgery in young patients. This approach may help surgeons achieve maximal detethering while preserving important sensory functions, consequently retaining the patient's quality of life.

Intraoperative feasibility of bulbocavernosus reflex monitoring during untethering surgery in infants and children

Bulbocavernosus reflex (BCR) monitoring is used to assess the integrity of urinary and bowel function. In this study, we evaluated the feasibility of BCR monitoring during untethering surgery in infants and children to predict postoperative urinary and bowel dysfunction. The records of 22 patients ranging from 4 days to 10 years old (mean 2.7 ± 3.3 years) were reviewed. Anesthesia was maintained by propofol or sevoflurane/opioid without neuromuscular blockade. BCR waveforms induced by electrical stimulation (20-40 mA, train-of-four pulses with 500 Hz) to the penis or clitoris were recorded from bilateral external anal sphincters. To assess the sensitivity and specificity of BCR monitoring, we investigated the association between a significant continuous decrease in BCR amplitude at the end of surgery and postoperative urinary and bowel dysfunction after surgery. Reproducible baseline BCR waveforms were successfully recorded in 20 of 22 patients (90.9%). A significant continuous decrease in BCR amplitude was observed in 8 patients. The results of intraoperative BCR monitoring included three true-positives, twelve true-negatives, five false-positives, and zero false-negatives. Therefore, the sensitivity and specificity of BCR monitoring used to predict postoperative urinary and bowel dysfunction were 100 and 70.6%, respectively. BCR monitoring during untethering surgery in infants and children under general anesthesia was found to be a feasible method to prevent postoperative urinary and bowel dysfunction.

Radiation Therapy for Pituitary Metastasis: Report of Four Cases

Aims and Background

To report the clinical outcomes of four patients with pituitary metastases treated with radiotherapy.

Methods

Retrospective chart review of four cases.

Results

The mean age of the patients was 66 years; two were women and two were men. The mean duration of symptoms at initial presentation of the primary tumor was 2.25 months. The location of the primary tumor was the breast in one case and the lung in three. Magnetic resonance imaging of the brain revealed sellar masses in all cases. The mean interval between the primary tumor diagnosis and the development of pituitary metastases was 22.5 months. The metastases were treated with radiation therapy (palliative/stereotactic/intensity modulated) at a mean dose of 3219 cGy. At the last follow-up, three patients were dead and one was alive.

Conclusions

Treatment with three-dimensional conformal radiotherapy or stereotactic radiotherapy is a suitable non-surgical option for patients with pituitary metastases.

Prevention and prediction of postoperative bowel bladder disorder using an anal plug electrode with Tc-MsEP monitoring during spine surgery

A retrospective study was performed to examine the efficacy of intraoperative monitoring of the external anal sphincter (EAS) muscle-evoked potential after a transcranial muscle-action potential (Tc-MsEP) in spinal cord surgery, and to evaluate alarm points for EAS waveform deterioration related to postoperative bowel bladder disorder (BBD). BBD is caused by damage to the hypogastric, pelvic, and pudendal nerves and leads to a significant reduction in quality of life. Intraoperative Tc-MsEP monitoring using the EAS is common to prevent neurological deficit, but the relationship of BBD with intraoperative monitoring of the EAS has not been examined. Waveform derivation from the EAS using a plug-type surface electrode was investigated in 123 spine surgeries in which Tc-MsEP was recorded intraoperatively outside the anal sphincter. An acceptable baseline waveform from the EAS was detected in 105 of the 123 cases (85.3%). Preoperative BBD was present in 16 cases, postoperative BBD occurred in 8 cases, and intraoperative waveform deterioration from the EAS was detected in 25 cases. The derivation rate was significantly lower in cases with preoperative BBD compared to those without BBD (62.5% vs. 88.9%, p<0.01). Waveform deterioration from the EAS had a sensitivity of 100%, specificity of 93.0%, positive predictive value of 50%, and negative predictive value of 100% for detection of postoperative BBD. All postoperative BBD was detected with an EAS amplitude decrease to <30% of baseline. Therefore, in spine surgery, a Tc-MsEP intraoperative EAS amplitude decrease to <30% of the control waveform may be useful for prediction of postoperative BBD.

Optimal stimulation parameters for intraoperative bulbocavernosus reflex in infants

OBJECTIVE The aim of this study was to establish optimal electric stimulation parameters for intraoperatively monitoring the bulbocavernosus reflexes (BCRs) in infants. METHODS The authors retrospectively reviewed the medical records of all infants (age < 24 months) who had undergone an untethering operation for tethered cord syndrome between May 2013 and February 2014 at a single institution and whose baseline BCR had been elicited during surgery. Using different combinations of stimulation parameters-number of stimulation pulses: 4 or 8 pulses, interpulse interval: 1, 2, or 5 msec, and polarity of stimulation: biphasic or monophasic-the authors compared the relative mean amplitude of 10 BCR responses (rmaBCRs) to each combination of parameters. RESULTS The rmaBCRs were larger with the 8-pulse stimulations than with the 4-pulse stimulations (p < 0.0001). There was a tendency, though not statistically significant, for larger rmaBCRs to be obtained with the longer interpulse interval in the 8-pulse stimulation (p = 0.1289). The biphasic stimulation produced larger rmaBCRs than the monophasic stimulation (p = 0.0005). CONCLUSIONS Biphasic 8-pulse stimulations with 5-msec or 2-msec intervals yield the largest BCR responses. Considering that an 8-pulse stimulation with 5-msec intervals may overlap the onset of the BCR, a biphasic 8-pulse stimulation with 2-msec intervals is recommended as the optimal stimulation paradigm to monitor intraoperative BCRs in infants.

Hypofractionated stereotactic radiosurgery for pituitary metastases

Pituitary metastases (PMs) are uncommon, representing only 1% of pituitary lesions. The diagnosis of PMs can be challenging and an optimal management remains to be determined. Here, we present a pilot clinical study on the efficacy and safety of hypofractionated stereotactic radiosurgery (SRS) with an optimized dosimetric plan in treating PMs. Between June 2013 and December 2014, seven consecutive patients (4 men and 3 women; median age 62 years) had been diagnosed with PMs based on their characteristic clinical and radiological features and subsequently treated using hypofractionated SRS. Primary cancers originated from the lung (n = 5) or the breast (n = 2). All patients presented with diabetes insipidus (DI). Anterior pituitary and visual dysfunction were combined in 4 and 3 patients, respectively. On magnetic resonance imaging (MRI), PMs involved the pituitary stalk and/or the posterior lobe in all patients. SRS of a cumulative marginal dose 31 Gy with dose-volume constraints for the optic apparatus was delivered in 5 daily fractions. As results, tumor was locally controlled in all patients with substantial responses on MRI (including complete remission in 4 patients). The median survival time was 14 months (range, 6-24 months) after SRS. DI and visual dysfunction improved in all patients, although anterior pituitary dysfunction did not recover. No patients experienced any deterioration in visual, pituitary, or other cranial nerve functions. These results suggest a promising role of hypofractionated SRS in treating PMs in terms of both tumor control and functional outcomes.

Against the odds: extraordinary recovery from complete cauda equina syndrome following L3 fracture. Time still matters

INTRODUCTION

Cauda equina syndrome secondary to lumbar fracture is a relative rare event. Although it is usually considered as an emergency, there is still controversy in the literature regarding the optimal timeframe of surgical intervention in complete spinal cord and cauda equina injuries.

CASE PRESENTATION

We report a case of a 24-year-old victim of a road traffic accident admitted with an L3 fracture causing complete cauda equina syndrome, who underwent early surgery within 12 h and made an extraordinary recovery (from AIS A to E).

DISCUSSION

Although the timing of surgery in complete traumatic spinal cord injury and cauda equina syndrome remains controversial, this case highlights the importance of early surgical intervention even in complete injuries.

Long-term evaluation of intraoperative neurophysiological monitoring-assisted tethered cord surgery

PURPOSE

Patients with tethered spinal cord have been investigated for short-term effects after tethered spinal cord surgery in the past. However, little is known about the long-term effects in this patient group. In this retrospective, longitudinal, observational study, a patient sample of a previous report of 65 patients was reassessed to observe the long-term effects of intraoperative neurophysiological monitoring-assisted tethered cord surgery.

METHODS

With the use of patient charts and a survey, patients were scored on four domains: (1) neurological deficits, (2) urological deficits, (3) pain symptoms, and (4) orthopedic deficits. Measurements were performed at four moments in time: (1) preoperatively, (2) postoperatively, (3) follow-up 1 (4.6 years), and (4) follow-up 2 (11.2 years). Besides this, a subgroup analysis and a quality of life questionnaire were performed.

RESULTS

When observing the symptom domains in the long-term, the pain domain appeared to improve most postoperatively after which it remained stable over time. The neurological and urological domains showed a stable, slightly decreasing trend in the long-term follow-up. The orthopedic domain showed a significant increase of the number of patients with scoliosis during the long-term follow-up.

CONCLUSIONS

Lasting effects of stability in the neurological, urological, and pain domains were observed. Close monitoring during follow-up might contribute to early recognition of progressive scoliosis, in spite of detethering, in a risk group defined by females who underwent tethered cord surgery at or under the age of 12 years old with either lipomyelomeningocele, split cord malformation, or myelomeningocele. Detethering does not appear to protect these patients against progressive scoliosis.

Metastatic involvement of the pituitary gland: a systematic review with pooled individual patient data analysis

PURPOSE

To report a rare case of pituitary metastasis (PM) from hepatocellular carcinoma (HCC) and help better understand the incidence of PM and its most common presenting symptoms through a pooled individual patient data analysis.

METHODS

Literature regarding PM was systematically reviewed with a pooled individual patient data analysis conducted. Pooled individual data analysis result is also compared with the result in a most recent systematic review.

RESULTS

Our results demonstrate that the incidence of PM among all intracranial metastases is 0.87% (95% CI 0.56, 1.18); it is 1.9% (95% CI 1.46, 2.34) among all autopsied cancer cases; it is 11.56% (95% CI 7.08, 16.04) among all breast cancer patients who had hypophysectomies and 12.83% (95% CI 10.5, 15.16) among all autopsied breast cancer patients. The fixed effect model showed that the incidence of PM in breast cancer patients group is significantly higher (p < 0.001) with an odds ratio of 6.71 (95% CI 4.24, 10.61). Breast and lung cancer are the most common primary cancer of PM with a percentage of 37.2 and 24.2 respectively. The next most common primary sites are prostate and kidney respectively, although the percentages for each are only about 5. Diabetes insipidus (DI) remains the most common symptom among all reported PM cases with a pooled incidence of 42.34% (95% CI 36.15, 48.53). Although not significant (χ(2) = 2.846, df = 1, p = 0.061), it is less common in the most recent reported cases which has a pooled incidence of 32.76% (95% CI 20.31, 45.21). DI is extremely rare in the reported PM cases from HCC (none of the eight cases presented with DI). The symptoms of anterior hypopituitarism (23.68 vs 39.66%, p = 0.015), visual deterioration (27.89 vs 41.38%, p = 0.039), cranial nerve palsies (21.58 vs 41.38%, p = 0.003) and headaches (15.79 vs 32.76%, p = 0.005) were reported significantly higher than previously described in the literature.

CONCLUSIONS

Pituitary metastasis is rare in patients with cancer, and the pituitary gland is an uncommonly involved location in patients with intracranial metastases. With advanced diagnostic imaging techniques and increased awareness about the manifestation of sellar lesions, the incidence of cranial nerve palsies and anterior pituitarism are higher than reported. This information may allow earlier diagnosis of PM.

Thyroid carcinoma with pituitary metastases: 2 case reports and literature review

We present 2 patients with pituitary metastases from thyroid carcinoma-the first from anaplastic thyroid carcinoma and the second from follicular thyroid carcinoma. The first patient, a 50-year-old lady, presented with 2-week history of hoarseness of voice, dysphagia, dyspnoea, and neck swelling. Imaging revealed metastatic thyroid cancer to lymph nodes and bone. Histology from surgery confirmed anaplastic thyroid cancer. She was found to have pituitary metastases postoperatively when she presented with nonvertiginous dizziness. She subsequently underwent radiotherapy and radioiodine treatment but passed away from complications. The second patient, a 65-year-old lady, presented with loss of appetite and weight with increased goitre size and dyspnoea. Surgery was performed in view of compressive symptoms and histology confirmed follicular thyroid carcinoma. Imaging revealed metastases to bone, lung, and pituitary. She also had panhypopituitarism with hyperprolactinemia and diabetes insipidus. She received radioiodine therapy but eventually passed away from complications.

Asymptomatic lipomas of the medullary conus: surgical treatment versus conservative management

OBJECT

The goal of this study was to compare long-term results of surgery with the outcomes of conservative treatment in patients with asymptomatic lipomas of the conus medullaris.

METHODS

The parents of 56 consecutive children with a diagnosis of asymptomatic lipoma of the conus medullaris underwent detailed neurosurgical consultation. The pros and cons of both prophylactic surgery and conservative treatment were carefully presented. Both options were offered, and the parents were free to choose the preferred management. A total of 32 children underwent surgical treatment, and 24 were conservatively treated. Afterward, all patients entered the same protocol of serial neurological and urological follow-up at the Centro Spina Bifida. The mean follow-up periods were 9.7 years in the surgical treatment group and 10.4 years in the conservative treatment group.

RESULTS

Permanent surgical morbidity was 3.1% (1 patient). During follow-up, tethered cord syndrome occurred in 9.7% of the surgically treated patients (3 of 32 patients) and in 29.1% of the conservatively managed children (7 of 24 patients). This difference did not result in statistical significance, but a clear trend in favor of surgery emerged. Young age at surgery and a cord/sac ratio < 50% appeared to be determining factors in the prevention of subsequent tethered cord syndrome.

CONCLUSIONS

The small size of this series does not provide enough statistical evidence that surgical treatment can really improve the natural history of asymptomatic lipomas of the conus medullaris. Nevertheless, surgery appears at least advisable since it reduces by 75% the odds of TCS (p = 0.067), which is quite close to statistical significance.

Below the belt: sensory mapping and monitoring in the sacral-pudendal region

Originally described in 1982, scalp somatosensory evoked potential responses can be recorded after stimulation of multiple different pudendal nerve- and sacral root-supplied structures. The resulting P40 response is usually the highest amplitude at Cz. Responses are generally easy to resolve and therefore should be of equivalent ease to follow for neurophysiologic intraoperative monitoring versus lower limb peripheral nerve somatosensory evoked potentials (e.g., tibial or fibular [peroneal] nerves), but sizeable reports of pudendal somatosensory evoked potential monitoring are few. Direct orthodromic sensory nerve action potential recording from the cauda equina in response to single such sacral stimuli has been reported of utility for preserving roots that participate in urinary control during dorsal rhizotomy procedures for spasticity. Technical application of both techniques is quite straightforward. As in most areas of neurophysiologic intraoperative monitoring, there are no well-constructed historical control series informing use of these techniques and, certainly, no clinical trials. Given the socially devastating consequences of urinary and anal continence disturbances and a fairly high rate of functional postoperative disturbances when sacral roots are manipulated, this field begs more active clinical investigation.

Pituitary metastasis of rhabdomyosarcoma: a case report and review of the literature

INTRODUCTION

The pituitary gland is an uncommon site for metastases, in particular from rhabdomyosarcoma. Some authors have reported a recent increase in the incidence of metastases at infrequent sites, such as brain or bone, probably due to the expanded treatment options and the resulting improved survival. Treatment options are limited, but must be discussed and adapted to the patient profile.

CASE PRESENTATION

We report the case of a 17-year-old Arabic man, diagnosed with alveolar rhabdomyosarcoma of the left shoulder, who, after several cycles of chemotherapy, presented symptoms and signs of pituitary dysfunction. To the best of our knowledge, it is the first case described.

CONCLUSIONS

Pituitary metastasis of rhabdomyosarcoma is a rare situation, which must be actively researched to have access to an optimal therapeutic approach.

Intraoperative neurophysiological monitoring in patients undergoing tethered cord surgery after fetal myelomeningocele repair

OBJECT

Fetal myelomeningocele closure has been shown to be advantageous in a number of areas. In this study, the authors report on neural function in patients who had previously undergone fetal myelomeningocele repair and returned to the authors' institution for further surgery that included intraoperative neurophysiological monitoring.

METHODS

The authors retrospectively reviewed data obtained in 6 cases involving patients who underwent fetal myelomeningocele repair and later returned to their institution for spinal cord untethering. (In 4 of the 6 cases, the patients also underwent removal of a dermoid cyst [3 cases] or removal of an epidermoid cyst [1 case] during the untethering procedure.) Records and imaging studies were reviewed to identify the anatomical level of the myelomeningocele as well as the functional status of each patient. Stimulated electromyography (EMG) and transcranial motor evoked potential (tcMEP) recordings obtained during surgery were reviewed to assess the functional integrity of the nerve roots and spinal cord.

RESULTS

During reexploration, all patients had reproducible signals at or below their anatomical level on stimulated EMG and tcMEP recordings. Corresponding to these findings, prior to tethering, all patients had antigravity muscle function below their anatomical level.

CONCLUSIONS

All 6 patients had lower-extremity function and neurophysiological monitoring recording signals at or below their anatomical level. These cases provide direct evidence of spinal cord and nerve root conductivity and functionality below the anatomical level of the myelomeningocele, further supporting that neurological status improves with fetal repair.

Endocrine side-effects of anti-cancer drugs: mAbs and pituitary dysfunction: clinical evidence and pathogenic hypotheses

mAbs are established targeted therapies for several diseases, including hematological and solid malignancies. These agents have shown a favorable toxicity profile, but, despite their high selectivity, new typical side-effects have emerged. In cancer patients, pituitary dysfunction may be mainly due to brain metastases or primary tumors and to related surgery and radiotherapy. Anticancer agents may induce hypopituitarism in patients cured for childhood cancers. These agents infrequently affect pituitary function in adult cancer patients. Notably, hypophysitis, a previously very rare disease, has emerged as a distinctive side-effect of ipilimumab and tremelimumab, two mAbs inhibiting the cytotoxic T-lymphocyte antigen-4 receptor, being occasionally seen with nivolumab, another immune checkpoint inhibitor. Enhanced antitumor immunity is the suggested mechanism of action of these drugs and autoimmunity the presumptive mechanism of their toxicity. Recently, ipilimumab has been licensed for the treatment of patients affected by metastatic melanoma. With the expanding use of these drugs, hypophysitis will be progressively encountered by oncologists and endocrinologists in clinical practice. The optimal management of this potentially life-threatening adverse event needs a rapid and timely diagnostic and therapeutic intervention. Hypopituitarism caused by these agents is rarely reversible, requiring prolonged or lifelong substitutive hormonal treatment. Further studies are needed to clarify several clinical and pathogenic aspects of this new form of secondary pituitary dysfunction.

Pituitary gland metastasis from rectal cancer: report of a case and literature review

Pituitary metastases are unusual complications of malignancies. In about only 2% of patients they origin from colorectal cancer (CRC), with breast and lung as the most common primary tumors. Nevertheless, some authors reported a recent increase of the incidence of metastases in infrequent sites, such as brain or bone, arising from gastrointestinal cancers, probably due to the expanded treatment options and the resulting improved survival. Here, we report the case of a 54-year old woman diagnosed with lung metastases from rectal cancer, who, after several cycles of radio- and chemotherapy, presented symptoms and signs of pituitary disfunction (i.e. diabetes insipidus, hypothyroidism and diplopy). The diagnosis of pituitary metastasis from rectal cancer was histologically confirmed after surgery.

Management of urological dysfunction in pediatric patients with spinal dysraphism: review of the literature

An intact, fully functional spine is the result of a complex sequence of embryological events involving both nervous and musculoskeletal system precursors. Deviations from this highly ordered system can result in congenital abnormalities ranging from clinically insignificant cosmetic changes to CNS malformations that are incompatible with life. Closure of the neural tube, which is believed to be the embryological event gone awry in these cases, is complete by just 28 days' gestation, often before pregnancy is detected. Although progress has been made to help prevent neural tube defects in the children of those attempting to conceive, these congenital deformities unfortunately continue to affect a startling number of infants worldwide each year. Furthermore, the precise mechanisms governing closure of the neural tube and how they might be interrupted remain elusive. What is known is that there are a large number of individuals who must deal with congenital spine dysraphism and the clinical sequelae on a daily basis. Bladder and urinary dysfunction are frequently encountered, and urological care is a critical, often neglected, component in the lifelong multidisciplinary approach to treatment. Although many treatment strategies have been devised, a need remains for evidence-based interventions, analysis of quality of life, and preemptive education of both caregivers and patients as they grow older. Pediatric neurosurgeons in particular have the unique opportunity to address these issues, often in the first few days of life and throughout pre- and postoperative evaluation. With proper management instituted at birth, many patients could potentially delay or avoid the potential urological complications resulting from congenital neurogenic bladder.

Lipomyelomeningocele: pathology, treatment, and outcomes

Lipomyelomeningocele represents a rare but complex neurological disorder that may present with neurological deterioration secondary to an inherent tethered spinal cord. Radiological testing is beneficial in determining the morphology of the malformation. Specialized testing such as urodynamic studies and neurophysiological testing may be beneficial in assessing for neurological dysfunction secondary to the lipomyelomeningocele. Early surgical intervention may be beneficial in preventing further neurological decline.

A case of pituitary metastasis from breast cancer that presented as left visual disturbance

Tumors that metastasize to the pituitary gland are unusual, and are typically seen in elderly patients with diffuse malignant disease. The most common metastases to the pituitary are from primary breast and lung cancers. We report a 65-year-old woman with pituitary metastasis from breast cancer who presented with recent-onset left progressive deterioration of visual acuity and visual field. The clinical diagnosis was made after brain and sellar magnetic resonance imaging showed a large sellar mass compressing the optic chiasm and invading the pituitary stalk. An otorhinolaryngology and neurosurgery team removed the tumor via a transsphenoidal approach, and this procedure obtained symptomatic relief. Postoperatively, metastasis from breast invasive ductal adenocarcinoma was confirmed histologically. We report this unusual case with a review of the relevant literature.

The use of BoneWelding® technology in spinal surgery: an experimental study in sheep

The innovative BoneWelding(®) technology, where ultrasound energy bonds bioresorbable implants to bone, was tested for its feasibility in spine surgery and its local thermal effects. The three tested concepts consisted of implementation of a resorbable plating system, two converging polymer pins and suture anchors to the cervical vertebral bodies. Bioresorbable polylactide implants (PLDLLA 70/30) were inserted ventrally into the third and fourth vertebral body of seven sheep, of which six were sacrificed at 2 months and one sheep immediately after temperature measurements during implant insertion. Polymer screws were used as controls. Qualitative, semi-quantitative histological, and quantitative histomorphometrical evaluation showed excellent anchorage of the implants, new mineralized bone at the implant-bone interface, no inflammatory cell reaction or thermal damage to the adjacent bone in response to the novel insertion technology. The application of two converging pins, parallel inserted polymer pins, or fusion of the implant to the polymer plates did not affect the overall excellent tissue tolerance of the technology. Temperature increase during insertion was noticed but never exceeded 47°C for less than 1 s. The BoneWelding(®) technology was proven to be safe and easy to apply.

Complications associated with the treatment for spinal ependymomas

Spinal cord ependymomas are rare neoplasms, comprising approximately 5% of all CNS tumors and 15% of all spinal cord tumors. Although surgery was once reserved for diagnosis alone, the evolution of surgical practices has elevated resection to the treatment of choice for these lesions. While technological advances continue to improve the capacity for gross-total resections and thus decrease the risk of recurrence, ependymoma spinal surgery still contains a variety of potential complications. The presence of neurological deficits and deterioration are not uncommonly associated with spinal cord ependymoma surgery, including sensory loss, dorsal column dysfunction, dysesthetic syndrome, and bowel and bladder dysfunction, particularly in the immediate postoperative period. Surgical treatment may also lead to wound complications and CSF leaks, with increased risk when radiotherapy has been involved. Radiation therapy may also predispose patients to radiation myelopathy and ultimately result in neurological damage. Additionally, resections of spinal ependymomas have been associated with postoperative spinal instability and deformities, particularly in the pediatric population. Despite the advances in microsurgical techniques and intraoperative cord monitoring modalities, there remain a number of serious complications related to the treatment of spinal ependymoma tumors. Identification and acknowledgment of these potential problems may assist in their prevention, early detection, and increased quality of life for patients afflicted with this disease.

The value of intraoperative neurophysiological monitoring in tethered cord surgery

PURPOSE

The value of intraoperative neurophysiological monitoring (IONM) with surgical detethering in dysraphic patients has been questioned. A retrospective analysis of our series of 65 patients is presented with special focus on technical set-up and outcome.

METHODS

All patients were diagnosed with a tethered cord (TC) due to spinal dysraphism. A high-risk group (HRG) was determined consisting of 40 patients with a lipomyelomeningocele and/or a split cord malformation sometimes in combination with a tight filum terminale. The surgical procedure was a detethering operation in all cases performed by a single surgeon during a 9-year period (1999-2008). A standard set-up of IONM was used in all patients consisting of motor-evoked potentials (MEP) evoked by transcranial electrical stimulation (TES) and electrical nerve root stimulation. In young patients, conditioning stimulation was applied in order to improve absent or weak MEPs.

RESULTS

IONM responses could be obtained in all patients. Postoperative deterioration of symptoms was found in two patients of whom one patient belonged to the HRG. Mean maximal follow-up of all 65 patients was 4.6 years (median 4.1 years). Long-term deterioration of symptoms was found in 6 of 65 patients with a mean follow-up of 5 years (median 5.3 years).

CONCLUSION

The use of IONM is feasible in all TC patients. The identification of functional nervous structures and continuous guarding of the integrity of sacral motor roots by IONM may contribute to the safety of surgical detethering.

Cauda equina repair in the rat: part 1. Stimulus-evoked EMG for identifying spinal nerves innervating intrinsic tail muscles

Cauda equina injuries may produce severe leg and pelvic floor dysfunction, for which no effective treatments exist. We are developing a rat cauda equina injury model to allow nerve root identification and surgical repair. One possible difficulty in implementing any repair strategy after trauma in humans involves the correct identification of proximal and distal ends of nerve roots separated by the injury. Two series of studies were carried out. In Series 1, we electrically stimulated segmental contributors to the dorsal and ventral caudales nerves in order to characterize the recruitment patterns of muscles controlling rat tail movements. In Series 2, we attempted to identify individual nerve roots forming the cauda equina by both level of origin and function (i.e., dorsal or ventral), based solely upon the recruitment patterns in response to electrical stimulation. For Series 1 studies, electrical stimulation of the segmental contributors showed that all nerve roots-from the sixth lumbar to the first coccygeal-contributed to recruitment of muscles found at the base of the tail. Intrinsic tail muscles lying more distally in the tail showed a more root-specific pattern of innervation. For Series 2, the rate of successful identification of an unknown nerve root as being ventral was very high (>95%), and only somewhat lower (approximately 80%) for dorsal roots. Correctly identifying the level of origin of that root was more difficult, but for ventral roots this rate still exceeded 90%. Using the rat cauda equina model, we have shown that stimulus-evoked EMG can be used to identify ventral nerve roots innervating tail muscles with a high degree of accuracy. These findings support the feasibility of using this conceptual approach for identifying and repairing damaged human cauda equina nerve roots based on stimulus-evoked recruitment of muscles in the leg and pelvic floor.