Retethering in children after sectioning of the filum terminale

Microsurgical approach for resection of the filum terminale internum in tethered cord syndrome-a case demonstration of technical nuances and vignettes

BACKGROUND

In tethered cord syndrome due to filum terminale pathology, the surgical approach to achieve detethering of the spinal cord may vary. Traditionally, sectioning the filum through a laminectomy at the lumbosacral level is performed.

METHOD

A microsurgical technique at a higher level to approach the filum below the conus tip is performed. This allows for removal of the entire distal portion of the filum through a limited interlaminar approach and dural opening.

CONCLUSION

We propose a technique to transect the filum terminale below the conus tip and extract the distal filum by releasing it from its intradural attachments to minimize any remnants of the filum terminale.

Filum Terminale: A Comprehensive Review with Anatomical, Pathological, and Surgical Considerations

The conus medullaris is the distal tapering end of the spinal cord, and the filum terminale (FT) is regarded as a bundle of non-functional fibrous tissue; therefore, some scholars call it the spinal ligament, while others describe the human FT as "remnants of the spinal cord." It was later found that in the human spinal cord, the FT is composed of an intradural segment and an epidural segment, and the end of the FT is connected to the coccyx periosteum. Because some nerve tissue is also found in the FT, as research progresses, FT may have the potential for transplantation. A lack of exhaustive overviews on the FT in the present literature prompted us to conduct this review. Considering that a current comprehensive review seemed to be the need of the hour, herein, we attempted to summarize previous research and theories on the FT, elucidate its anatomy, and understand its pathological involvement in various diseases.

A critical analysis of surgery for occult tethered cord syndrome

INTRODUCTION

Tethered cord syndrome (TCS) is an amalgamation of neurological, urological, orthopedic, and dermatologic signs and symptoms with radiographic evidence of a thickened filum and low-lying conus. Surgical sectioning of the filum and disconnection of any tethering entities such as dermal sinus tracts or lipomas has been shown to improve outcomes. The manifestation of TCS symptoms in the absence of a low-lying conus has been referred to as occult tethered cord syndrome (OTCS) and is much less well reviewed in the literature. To date, there has only been one randomized controlled trial examining the effect of intervention in OTCS; therefore, contemporary data is often elicited from limited cohorts.

OBJECTIVE

To perform a comprehensive literature review of management in OTCS and evaluate treatment response rates to sectioning of the filum terminale.

RESULTS

Seventeen papers met inclusion criteria for our review. Sample sizes ranged from 8 to 60 children, and results were mixed, often dependent on study design, definition of typical OTCS symptoms, and follow-up intervals. Symptomatic improvement was observed in > 50% of patients for all but one study; however, the recurrence rates were highly variable.

CONCLUSION

The data regarding the efficacy of surgical treatment in OTCS is mixed and merits more rigorous scientific examination with strict and clear parameters regarding symptomatic operationalization and follow-up time points to monitor for TCS recurrence.

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.

Retethering after transection of a tight filum terminale, postoperative MRI may help to identify patients at risk

PURPOSE

Retethering after transection of a tight filum terminale (TFT) deemed to be a rare and usually only years after initial surgery occurring complication. Possible perioperative factors that might influence the retethering rate or help to allow a prognostic risk assessment are still poorly investigated. The aim of this study was to analyze our patient cohort who underwent a TFT transection by assessing clinical outcome, retethering rate, and pre- and postoperative MRI studies.

METHODS

All consecutive patients undergoing transection of a TFT from January 2011 to December 2018 were evaluated. Inclusion criteria were defined as exclusive TFT intervention and a minimum follow up period of 1 year. Epidemiological data, treatment modalities, complication characteristics, and MRI studies were recorded and analyzed.

RESULTS

A total of 58 patients met our inclusion criteria. The retethering rate in our patient cohort was 5.2% (3/58); one of the three patients developed two episodes of a retethering. Patients with an unchanged conus level, no improvement in the syringomyelia, and an unchanged thickness of the spinal cord postoperatively seem to have a significant higher risk to develop a retethering episode in the follow-up.

CONCLUSION

Retethering after transection of the filum terminale did occur more often than expected. Certain existing factors on the routine postoperative MR images may help to identify patients with an increased likelihood to develop a retethering episode. These results may contribute to improve the follow-up for patients after transection of a TFT and may facilitate adequate treatment.

Retethering : A Neurosurgical Viewpoint

During the follow-up period after surgery for spinal dysraphism, a certain portion of patients show neurological deterioration and its secondary phenomena, such as motor, sensory or sphincter changes, foot and spinal deformities, pain, and spasticity. These clinical manifestations are caused by tethering effects on the neural structures at the site of previous operation. The widespread recognition of retethering drew the attention of medical professionals of various specialties because of its incidence, which is not low when surveillance is adequate, and its progressive nature. This article reviews the literature on the incidence and timing of deterioration, predisposing factors for retethering, clinical manifestations, diagnosis, surgical treatment and its complications, clinical outcomes, prognostic factors after retethering surgery and preventive measures of retethering. Current practice and opinions of Seoul National University Children’s Hospital team were added in some parts. The literature shows a wide range of data regarding the incidence, rate and degree of surgical complications and long-term outcomes. The method of prevention is still one of the main topics of this entity. Although alternatives such as spinal column shortening were introduced, re-untethering by conventional surgical methods remains the current main management tool. Re-untethering surgery is a much more difficult task than primary untethering surgery. Updated publications include strong skepticism on re-untethering surgery in a certain group of patients, though it is from a minority of research groups. For all of the abovementioned reasons, new information and ideas on the early diagnosis, treatment and prevention of retethering are critically necessary in this era.

Tethered cord in children with anorectal malformations with emphasis on rectobladder neck fistula

PURPOSE

To find the incidence of tethered cord (TC) in patients with anorectal malformations (ARM) and to determine the relationship between bowel/urinary control and TC in a subset of patients with rectobladder neck fistula (RBNF).

METHODS

The database of a tertiary medical center was retrospectively collected for all patients treated for ARM from 1980 to 2012. All patients with TC and RBNF were identified.

RESULTS

Among 790 patients, who underwent screening for TC, 285(36%) were diagnosed with TC. Eleven of 37 screened patients with RBNF were diagnosed with TC. The median follow-up period was 49 months (range 2-222 months). TC was diagnosed in 3/18(16.6%) patients with sacral ratio (SR) ≥ 0.7; 4/12(33.3%) with SR 0.41-0.69; and 4/7(57.1%) patients with SR 0-0.4. The association of TC in RBNF patients had a negative influence in the prognosis for bowel and urinary control.

CONCLUSION

The incidence of TC among patients with ARM is 36%. Incidence of TC among patients with RBNF correlates with SR value and is higher with lower SR. Patients with RBNF and TC have dismal prognosis for bowel control, unrelated to their SR status. Many unresolved questions related to the management of ARM patients with asymptomatic TC still remain.

Microsurgical efficacy in 326 children with tethered cord syndrome: a retrospective analysis

Tethered cord syndrome is a progressive disease with a typically insidious onset in infants and children, and which can lead to persistent progress of neurological deficits and a high rate of disability without timely intervention. The purpose of this study was to investigate the curative effect of microsurgery in children with different types of tethered cord syndrome. In this study, we analyzed 326 patients with tethered cord syndrome, aged from 2 months to 14 years old, who were followed for 3-36 months after microscopic surgery. Based on clinical manifestations and imaging findings, these patients were classified into five types: tight filum terminale (53 cases), lipomyelomeningocele (55 cases), lipomatous malformation (124 cases), postoperative adhesions (56 cases), and split cord malformation (38 cases). All patients underwent microsurgery. Curative effects were measured before and 3 months after surgery by Spina Bifida Neurological Scale based on sensory and motor functions, reflexes, and bladder and bowel function. The results showed that Spina Bifida Neurological Scale scores improved in all five types after surgery. Overall effective rates in these patients were 75%. Effective rates were 91% in tight filum terminale, 84% in lipomyelomeningocele, 65% in lipomatous malformation, 75% in postoperative adhesion, and 79% in split cord malformation. Binary logistic regression analysis revealed that types of tethered cord syndrome (lipoma-type or not) and symptom duration before surgery were independent influencing factors of surgical outcome. These results show that therapeutic effect is markedly different in patients with different types of tethered cord syndrome. Suitable clinical classification for tethered cord syndrome will be helpful in predicting prognosis and guiding treatment. This trial has been registered in the Chinese Clinical Trial Registry (registration number: ChiCTR1800016464).

Transhiatal Approach to Filum Terminale Externum Sectioning in Adult Patient With Tethered Cord Syndrome: Case Report

BACKGROUND AND IMPORTANCE

An adult patient was referred to our department for tethered cord syndrome. A lumbar magnetic resonance imaging showed a conus medullaris at the S2 level and the caudal part of the dural sac at the S3 level. We present a minimally invasive spine surgery procedure at the hiatus level for the treatment of tethered cord syndrome by the surgical section of the filum terminale externum, which avoids bone demolition.

CLINICAL PRESENTATION

A 65-yr-old Caucasian man was referred for dysesthesia and a burning sensation in his lower limbs, which was both spontaneous and triggered by contact with his clothes. He had been unable to walk for 5 mo due to severe pain and stiffness in his legs. He suffered from minimal, occasional urinary incontinence and complained about muscle cramps in the supine position that prevented him from sleeping; he was only able to sleep when sitting in a wheelchair. Informed patient consent was obtained for the procedure; no opinion was requested from the Ethics Committee. A minimally invasive transhiatal approach with the sectioning of the superficial dorsal sacrococcygeal ligament without the removal of bone tissue allows access to the sacral canal, after which it is possible to section the filum terminale externum using a microsurgical technique.

CONCLUSION

After a 6-mo follow-up period, the patient no longer had dysesthesia and pain in his legs, and was able to walk, albeit just a few meters. This surgical technique has the advantage of minimally invasive spine surgery, has few complications, and avoids risk of retethering.

Clinical Outcomes of Primary and Revision Untethering Surgery in Patients with Tethered Cord Syndrome and Spinal Bifida

BACKGROUND

Tethered cord syndrome (TCS) is an increasingly recognized clinical condition, with untethering surgery considered the classically effective treatment. Yet, as evidence has aggregated, the surgical outcomes of untethering remain controversial. This study aimed to systematically evaluate the clinical outcomes in patients who underwent primary or revision untethering.

METHODS

This retrospective study was conducted at the Department of Spine Surgery of Changzheng Hospital between January and December 2016. Patients with TCS who underwent untethering surgery were recruited for the study. Information collected included demographic data, main clinical manifestations, and outcomes after untethering surgery.

RESULTS

A total of 112 patients (60 males and 52 females) were included in this study, with mean follow-up of 13.7 years. The surgical outcomes of the primary untethering varied among symptoms, with remission rates of 30.0% for pain, 24.4% for paresthesia, 18.6% for motor deficit, 12.6% for bladder dysfunction, and 21.2% for bowel dysfunction. Moreover, 23.3%-40.2% of patients suffered deterioration after surgery during the follow-up period. Twenty-eight patients underwent revision untethering surgery. In these patients, the remission rate decreased by 5.6%-16.7% compared with the primary operation. Moreover, most patients (58.8%-70.6%) experienced no benefits after revision surgery.

CONCLUSIONS

With a possible high risk of recurrence, further exploration of the indications and timing of the untethering surgery is needed. Conservative treatment and omnidirectional care might be a better choice for patients with retethering with recurrent symptoms.

Magnetic resonance imaging in the prone position and the diagnosis of tethered spinal cord

OBJECTIVE Tethered cord syndrome (TCS) is a neurosurgical disorder with varied clinical manifestations believed to result from vascular compromise due to stretch forces on the spinal cord. Conventional supine MRI findings may include a low-lying conus medullaris, thickened or fat-infiltrated filum terminale, or lipoma; however, imaging sensitivity and specificity for tethered cord can be low. The purpose of this study was to evaluate the utility of prone MRI in the diagnosis of tethered and retethered spinal cord. METHODS Medical records were reviewed in 41 patients who underwent surgical release of tethered cord and in whom preoperative prone MRI sequences were available. Patients were divided into Group 1 (new TCS diagnosis) and Group 2 (recurrent TCS after previous untethering). Absolute conus ventral motion and motion as a percentage of canal width between supine and prone positions was measured in these 2 groups via sagittal T2-weighted sequences; these groups were compared with 30 consecutive patients (Group 3) who were classified as the normal control group. RESULTS The mean ventral motion was as follows: Group 1 (absolute: 0.5 ± 0.5 mm [range 0-2.4 mm]; canal percentage: 3.7% ± 3.9% [range 0%-16.3%]); Group 2 (absolute: 0.4 ± 0.7 mm [range 0-2.6 mm]; canal percentage: 2.2% ± 3.7% [range 0%-14.0%]); and Group 3 (absolute: 3.4 ± 1.3 mm [range 1.4-5.6 mm]; canal percentage: 22.0% ± 7.2% [range 10.5%-36.1%]). Whereas 38/41 surgically treated patients with TCS had diminished (< 10% canal width) ventral motion on preoperative MRI, 30/30 controls had > 10% canal width motion. Sensitivity and specificity were thereby calculated as 92.7% and 100%, respectively. CONCLUSIONS In the present series, prone imaging is found to be a sensitive and specific tool, and the authors believe it may have a role as supportive evidence in the diagnosis of tethered and retethered spinal cord.

Etiological Theories of Adolescent Idiopathic Scoliosis: Past and Present

Adolescent idiopathic scoliosis is one of the most common spinal deformities, yet its cause is unknown. Various theories look to biomechanical, neuromuscular, genetic, and environmental origins, yet our understanding of scoliosis etiology is still limited. Determining the cause of a disease is crucial to developing the most effective treatment. Associations made with scoliosis do not necessarily point to causality, and it is difficult to determine whether said associations are primary (playing a role in development) or secondary (develop as a result of scoliosis). Scoliosis is a complex condition with highly variable expression, even among family members, and likely has many causes. These causes could be similar among homogenous groups of AIS patients, or they could be individual. Here, we review the most prevalent theories of scoliosis etiology and recent trends in research.

Evaluation and management of tethered cord syndrome in occult spinal dysraphism: Recommendations from the international children's continence society

AIMS

As awareness and frequency of tethered spinal cord (TSC) related to occult spinal dysraphism (OSD) has increased with magnetic resonance imaging (MRI), variability exists in its evaluation and management. Due to no published level I data, we summarize the current International Children's Continence Society (ICCS) recommendations for diagnosis and treatment of OSD.

METHODS

Guidelines were formulated based on analysis of pertinent literature and consensus among authors. This document was vetted by the multidisciplinary members of the ICCS via its website before submission for peer review publication.

RESULTS

The more frequent diagnosis of OSD is associated with increased operative intervention. Spinal cord untethering (SCU) has a highly variable risk profile, largely dependent on the specific form of OSD. Progressive neurological deterioration attributed to "tethered cord" may occur, with or without surgery, in selected forms of OSD whereas other cohorts do well.

CONCLUSION

Infants with classic cutaneous markers of OSD, with progressive neurologic, skeletal, and/or urologic findings, present no diagnostic or therapeutic dilemma: they routinely undergo MRI and SCU. Conversely, in asymptomatic patients or those with fixed, minor abnormalities, the risk profile of these OSD cohorts should be carefully considered before SCU is performed. Irrespective of whether or not SCU is performed, patients at risk for progression should be followed carefully throughout childhood and adolescence by a multidisciplinary team.

The natural history and management of patients with congenital deficits associated with lumbosacral lipomas

INTRODUCTION

Many patients with lumbosacral lipoma are asymptomatic; however, a significant proportion will have neurological deficits present at birth. Implication of these deficits with respect to natural history and management are not well understood.

METHODS

A retrospective review of all infants with lumbosacral lipoma seen at BCCH between 1997 and 2013 was carried out. The study population was stratified on the presence of a congenital, non-progressive deficit and subdivided on treatment approach. The subsequent developments of deficits resulting in untethering procedures were recorded.

RESULTS

Of the 44 infants in this study, 24 patients had no neurologic deficit while 20 patients had a fixed, non-progressive deficit evident at birth. Ten of 24 patients without a neurological deficit at birth underwent a prophylactic untethering with 3 eventually requiring repeat untethering after, on average, 62.7 months. Eleven of 14 asymptomatic, monitored patients required untethering for clinical deterioration. Two required a second untethering procedure after 48.7 months. Ten of 20 infants with congenital deficits present at birth underwent prophylactic untethering, and 4 required further surgery after 124 months. Ten patients underwent observation with 8 eventually requiring surgery. Two required repeat untethered after 154 months. The complication rates and operative burden for patients are similar whether prophylactic or delayed surgery is performed.

CONCLUSION

The presence of congenital neurologic deficit does not affect the likelihood of deterioration in patients managed expectantly; prophylactic detethering of these patients did not prevent delayed neurologic deterioration. Comparing the need for repeat surgery in prophylactically untethered patients with initial untethering of patients operated upon at the time of deterioration, prophylactic untethering may confer a benefit with respect to subsequent symptomatic tethering if complication rates are low. However, in a setting with multidisciplinary follow-up, a period of observation for patients and intervention when patients become symptomatic is an acceptable approach for patients with or without congenital deficits.

Fecal incontinence as a predominant symptom in a case of multiply recurrent tethered cord: diagnosis and operative strategies

Recurrent manifestations of tethered spinal cord after an initial operative intervention for a simple fatty filum terminale is fairly uncommon. The authors present the case of an unusual clinical course in which there were 3 distinct episodes of recurrence, each time presenting predominantly as fecal incontinence and resolving with operative intervention. Typical signs of tethering were absent on radiological evaluation, and operative intervention was based on clinical grounds. Intraoperatively, sacral nerve roots to the anal sphincter were found tethered to the filar stump with electrophysiological evidence of regained activity on disentanglement. To the best of the authors' knowledge, a similar clinical course or operative findings have not been reported.