Clinical significance of terminal syringomyelia in association with pediatric tethered cord syndrome

Optimizing Therapeutic Strategies for Syringomyelia Associated with Tethered Cord Syndrome: A Comprehensive Review

This review highlights the need for therapeutic guidelines for syringomyelia associated with tethered cord syndrome (TCS) caused by spinal dysraphism (SD). A comprehensive literature review was conducted, selecting twelve articles to analyze common therapeutic strategies. Surgical cord untethering alone has recently become a preferred treatment, with 45 ± 21.1% of patients experiencing remission or improvement, 47 ± 20.4% unchanged and asymptomatic, and 4 ± 8% worsened. Untethering with direct surgical drainage for the syrinx had better outcomes than untethering alone (78% vs. 45%, p = 0.05). Terminal syringostomy was beneficial for syrinxes extending to the filum terminale but not for asymptomatic small syrinxes with a syrinx index < 0.4. Syrinx shunting was recommended for symptomatic large syrinxes (>2 cm in length and syrinx index > 0.5). Various shunt procedures for syrinxes are still advocated, mainly for refractory syringomyelia in Chiari malformation, posttraumatic cases, SD, or other causes. Personalized surgical methods that address the root cause of syringomyelia, particularly those improving cerebrospinal fluid flow, offer promising results with minimized complications. Ongoing studies are required to enhance management strategies for syringomyelia associated with TCS, optimize patient outcomes, and reduce the risk of recurrent symptoms.

Disparities in indications and outcomes reporting for pediatric tethered cord surgery: The need for a standardized outcome assessment tool

PURPOSE

Tethered cord syndrome (TCS) is characterized by abnormal attachment of the spinal cord neural elements to surrounding tissues. The most common symptoms include pain, motor or sensory dysfunction, and urologic deficits. Although TCS is common in children, there is a significant heterogeneity in outcomes reporting. We systematically reviewed surgical indications and postoperative outcomes to assess the need for a grading/classification system.

METHODS

PubMed and EMBASE searches identified pediatric TCS literature published between 1950 and 2023. Studies reporting surgical interventions, ≥ 6-month follow-up, and ≥ 5 patients were included.

RESULTS

Fifty-five studies representing 3798 patients were included. The most commonly reported non-urologic symptoms were nonspecific lower-extremity motor disturbances (36.4% of studies), lower-extremity/back pain (32.7%), nonspecific lower-extremity sensory disturbances (29.1%), gait abnormalities (29.1%), and nonspecific bowel dysfunction/fecal incontinence (25.5%). Urologic symptoms were most commonly reported as nonspecific complaints (40.0%). After detethering surgery, retethering was the most widely reported non-urologic outcome (40.0%), followed by other nonspecific findings: motor deficits (32.7%), lower-extremity/back/perianal pain (18.2%), gait/ambulation function (18.2%), sensory deficits (12.7%), and bowel deficits/fecal incontinence (12.7%). Commonly reported urologic outcomes included nonspecific bladder/urinary deficits (27.3%), bladder capacity (20.0%), bladder compliance (18.2%), urinary incontinence/enuresis/neurogenic bladder (18.2%), and nonspecific urodynamics/urodynamics score change (16.4%).

CONCLUSION

TCS surgical literature is highly variable regarding surgical indications and reporting of postsurgical outcomes. The lack of common data elements and consistent quantitative measures inhibits higher-level analysis. The development and validation of a standardized outcomes measurement tool-ideally encompassing both patient-reported outcome and objective measures-would significantly benefit future TCS research and surgical management.

An Effective Surgical Method for Terminal Syringomyelia: Terminal Ventriculostomy-Associated "V"-Type Ostomy

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

We aimed to evaluate the effectiveness of terminal ventriculostomy in treating tethered cord syndrome (TCS) combined with terminal syringomyelia (TS) and describe "V"-type ostomy as an effective surgical method to avoid relapsing syringomyelia based on terminal ventriculostomy.

METHODS

We retrospectively analyzed the clinical and radiological data of 28 patients admitted to the Department of Neurosurgery, PLA General Hospital who had been diagnosed with TCS combined with TS and underwent terminal ventriculostomy-associated "V"-type ostomy between January 2011 and January 2016. We classified patients' clinical outcomes into 4 levels according to the Spinal Bifida Neurological Scale: markedly improved, improved, stable, and deteriorated. The size of the syrinx cavity was quantified using the syrinx index, and there was a difference in syrinx cavity size between pre-operation and post-operation.

RESULTS

Twenty-eight patients were followed up for 36 months. We found that each syrinx cavity shrunk by at least 50%. More than 90% of patients had achieved "markedly improved" and "improved" outcomes during the follow-up visit. Moreover, no patient relapsed for up to 36 months post-surgery.

CONCLUSION

Terminal ventriculostomy has a beneficial effect on TS, particularly on the syrinx cavity extending to the filum terminale. For this special cavity, we advocate the use of terminal ventriculostomy-associated "V"-type ostomy to avoid potential relapse. As a safe, convenient, and persistently effective approach, terminal ventriculostomy-associated "V"-type ostomy can be considered a promising alternative method for treating TCS combined with TS in clinical practice.

Characterizing syringomyelia and its clinical significance in 140 patients with lipomyelomeningocele

OBJECTIVE

The aims of this study were to characterize syringomyelia in patients with lipomyelomeningocele (LMMC) and investigate the association between the presence of a syrinx and patient neurological deficits.

METHODS

Patients with LMMC who had been admitted between 2007 and 2020 were included in the study. Syringomyelia on magnetic resonance imaging (MRI) was classified into three groups: true syrinx, early syrinx, and presyrinx. The correlation of clinical deficits (at birth, new onset, and progressive) and type of lipoma with the presence and type of syrinx was studied.

RESULTS

Among a total of 140 patients, the median age was 2.5 (IQR 1.3-9) years. Neurological deficits were present at birth in 75 (53.6%) patients, but 67 (47.9%) had new-onset deficits or progression of their birth deficits. The most common type of spinal lipoma was the transitional type (75.7%). Thirty-nine (27.9%) patients had a syrinx (37 with a true syrinx, 2 with an early syrinx), and 25 (17.9%) patients had a presyrinx. There was no significant correlation between the presence of a syrinx and patient neurological deficits. However, patients with a syrinx that was not adjacent to the lipoma (≥ 1 vertebral level away) had a higher incidence of deficits at birth (p = 0.045), whereas those with a syrinx spanning ≥ 5 vertebral levels had a higher incidence of progressive neurological deficits (p = 0.04). Six (75%) of 8 patients in whom serial MRI had shown syrinx progression had clinical worsening.

CONCLUSIONS

Syrinx location with respect to the spinal lipoma, syrinx length, and progressive syringomyelia may have clinical significance in patients with LMMC.

Value of pre- and postnatal magnetic resonance imaging in the evaluation of congenital central nervous system anomalies

Fetal MRI and neonatal MRI of the central nervous system (CNS) are complementary tools that can help to accurately counsel and direct the management of children with anomalies of the central nervous system. Postnatal MRI can add to fetal MRI by allowing for monitoring of changes in the severity of disease, better delineation of a suspected prenatal anomaly, evaluation for secondary pathologies related to the primary diagnosis, and surgical management direction. In this review we discuss the roles of fetal and neonatal MRI in the diagnosis and treatment of congenital anomalies of the CNS through a series of case examples and how both are important in patient management.

The Management of Idiopathic and Refractory Syringomyelia

Idiopathic syringomyelia (IS) and refractory syringomyelia (RS) are types of syringomyelia that often pose a management challenge and are associated with long-term clinical sequela. They are usually an epiphenomenon reflecting an underlying pathology where the treatment of the primary cause should be the aim for any surgical intervention. In the case of IS, the initial step is agreeing on the definition of the terms idiopathic and syringomyelia. After a rigorous exhaustive clinic-radiological workup, only IS patients with progressive neurology are treated, usually unblocking subarachnoid cerebrospinal fluid (CSF) pathway obstruction somewhere in the thoracic spinal canal and reserving shunting techniques to nonresponsive cases. Similar to IS, also RS is multifactorial, and its management varies based on the initial pathology, strongly supported by radiological and clinical features. We aim to address this topic focusing on the etiopathology, investigation paradigm, and surgical pathway, formulating algorithms of management with available evidence in literature. Surgical techniques are discussed in detail.

Clinical Significance of Terminal Syringomyelia and Accompanying Congenital Anomalies of Neurosurgical Interest in Adult and Pediatric Patients with Tethered Cord Syndrome

Magnetic resonance imaging (MRI) can be used to examine tethered cord syndrome (TCS) and terminal syringomyelia (TS). Additionally, there is increasing evidence of an association between congenital anomalies and TCS. We aimed to identify the clinical and radiological characteristics of syringomyelia and other anomalies in pediatric and adult patients with TCS. This study included 54 TCS patients (mean age, 17.37 ± 15.83 years; 31 females) admitted to our department between 2010 and 2019. The patients were divided into two age groups: pediatric (<18 years; 63%) and adult (>18 years). Clinical findings, direct vertebrae radiographs, lower extremity radiographs, and spinal/cranial MRI findings were used to evaluate all patients. Computed tomography (CT) was performed to reveal the structure of the septum in patients with Diastematomyelia. Cranial ultrasonography or CT was performed if the fontanel was open or closed, respectively, in pediatric hydrocephalus cases. Pelvic ultrasonography and urodynamic tests were performed to evaluate other comorbid anomalies and urinary system pathologies. A thick filum terminale (73.3%) and diastematomyelia (44.4%) were found to cause spinal tension. The most common accompanying pathology was syringomyelia (78%). The common symptoms were urinary incontinence and bowel problems (71%), scoliosis (68%), and progressive lower extremity weakness (64.4%). It is difficult to distinguish the exact cause of symptoms in patients with TCS and TS. Due to the greater occurrence of other congenital spinal anomalies accompanying TCS, both preoperative symptoms and clinical findings are more severe in the pediatric group than in the adult group, and postoperative results may be more negative.

Association between filum terminale internum length and pain in Cavalier King Charles spaniels with and without syringomyelia

Background

Lumbar syringomyelia (SM), lumbosacral pain, and more caudal spinal cord termination are reported in Cavalier King Charles spaniels (CKCS). Data are lacking on the clinical relevance of alterations in their spinal cord terminal structures.

Objectives

To compare spinal cord termination level and filum terminale internum length (FTIL) with presence of lumbar SM and clinical signs in CKCS.

Animals

Forty‐eight CKCS.

Methods

In this prospective study, pain was quantified using owner and clinician assessments. Vertebral level of spinal cord and dural sac termination, presence of SM, and FTIL were determined from sagittal magnetic resonance imaging (MRI) sequences. Kappa and intraclass correlation (ICC) analyses determined interobserver reliability. The MRI findings were compared to owner and clinician‐reported pain quantification.

Results

Interobserver reliability was good for spinal cord and dural sac termination (kappa = 0.61 and 0.64, respectively) and excellent for FTIL (ICC: 92% agreement). The spinal cord terminated at 6th lumbar vertebra in 1, 7th lumbar vertebra in 31, and the sacrum in 15 dogs, and termination level was associated with lumbar SM (P = .002) but not clinical signs. Mean FTIL was 2.9 ± 1.08 mm; it was associated with owner‐reported pain (P = .033) and spinal palpation scores (P = .023). Painful CKCS without SM had shorter FTIL compared to normal CKCS and painful CKCS with SM (P = .02).

Conclusions

Painful CKCS without SM have decreased distance between the termination of the spinal cord and dural sac, suggesting a shorter FTIL. More caudal spinal cord termination is associated with development of lumbar SM.

MRI characteristics of the fetal tethered spinal cord: a comparative study

Purpose: To compare fetuses and children with confirmed tethered cord syndrome to age-matched controls to provide a reference for prenatally identifying tethered spinal cord and to identify salient points on MRI for diagnosis.Materials and Methods: This retrospective study enrolled 13 fetuses and 20 children with tethered cord syndrome, and age-matched counterparts were included as controls. The MRI features including concomitant malformations, position of the conus medullaris, and thickened filum terminale of the two patient groups were evaluated and compared. Levels of the conus medullaris were discriminated between patients and an equivalent number of controls.Results: Various concomitant malformations manifested on the MRI of all patients, and there were differences between the two patient groups. Significant differences of the level of the conus medullaris were found between the fetal and child patients (U, 26.50; Z, -3.87; p < 0.001) and between the normal fetus and child controls (U, 23.50; Z, -4.13; p < 0.001). The position of the conus medullaris was visibly lower in the patient groups than in the control groups. No significant difference in the diameters of the filum terminale was found between the fetal and child patients (p = 0.67).Conclusions: The current study's results indicate that tethered spinal cord syndrome can be diagnosed in utero with MRI combined with several characteristics, particularly the position of the conus medullaris. Special attention should be paid to the gestational age of the fetus because normal changes in spinal cord position occur with gestational development.

The incidence and effect of tethered cord release for tethered cord syndrome in patients with myelomeningocele: a population-based study

OBJECTIVE

The goal of this study was to establish an incidence and assess the effect of tethered cord release for tethered cord syndrome in patients with myelomeningocele.

METHODS

The study population was based on the Western Denmark Myelomeningocele Database, which contains all patients born with myelomeningocele in western Denmark since 1970. The study population was cross-referenced in 2015 with a database for surgical procedures containing all surgical procedures performed in the central Denmark region since 1996. Patients alive between 1996 and 2015 were identified. Incidences was calculated and presented for year of age. File reviews were conducted for all patients who underwent the procedure. Follow-up was divided into short-term and long-term follow-up.

RESULTS

One hundred sixty-six patients were alive during various time periods between 1996 and 2015. Of these, 45 patients underwent the procedure. Seven underwent reoperation. The median age for the procedure was 12 years and the highest incidence was found at 15 years of age. Incidence was bimodal with highest incidence in children and adolescents. The most common indications were progressive spine deformity (40%), deteriorating ambulation (38%), and deteriorating neurogenic bladder and/or bowel dysfunction (32%). The mean short-term follow-up was 4.7 months and the mean long-term follow-up was 72.6 months. Postoperatively, the majority had improved (27%) or stabilized (27%) at short-term follow-up. At long-term follow-up, most patients were stable (27%) or had deteriorated (24%). For both follow-up terms there was a loss of approximately one-third of all patients. Complications occurred in 17% of the procedures.

CONCLUSIONS

In this population-based study, tethered cord release has the highest incidence in children and adolescents. The beneficial effect of the procedure seems to be short term. Due to the uncertainty of a long-term effect of the procedure in patients with myelomeningocele and the registered complications, the authors suggest that this surgical indication should be reserved for well-selected patients.

Syringomyelia in the Tethered Spinal Cords

Cases of syringomyelia associated with spinal dysraphism are distinct from those associated with hindbrain herniation or arachnoiditis in terms of the suspected pathogenetic mechanism. The symptoms of terminal syringomyelia are difficult to differentiate from the symptoms caused by spinal dysraphism. Nonetheless, syringomyelia has important clinical implications, as it is an important sign of cord tethering. The postoperative assessment of syringomyelia should be performed with caution.

External validation of a new classification of spinal lipomas based on embryonic stage

OBJECTIVE

Contention exists regarding appropriate classification and management of spinal lipomas (SLs). Given the heterogeneity of SLs, omissions and overlap between surgically incomparable groups exist in conventional classification systems. The new classification of spinal lipoma (NCSL) recently proposed by Morota et al. delineates morphology by embryological pathogenesis and the resultant operative difficulty. Here, the authors aimed to validate the NCSL by applying it to patients who had been operated on at their institution.

METHODS

All children who had undergone resection for SL between 2014 and 2018 were included in this analysis. MRI studies were independently reviewed and classified by three adjudicators. Baseline characteristics, inter-adjudicator agreement, coexisting anomalies and/or malformations, and postoperative outcomes and complications were analyzed.

RESULTS

Thirty-six patients underwent surgical untethering for SL: NCSL type 1 in 5 patients (14%), type 2 in 14 patients (39%), type 3 in 4 patients (11%), and type 4 in 13 patients (36%). All classification was agreed on first assignment by the adjudicators. Radical or near-radical resection, which was attempted in all patients, was always possible in those with type 1 and 4 SL, but never in those with type 2 and 3 SL. Neurological stabilization and/or improvement were observed in all patients at the last follow-up.

CONCLUSIONS

The NCSL was found to be a logical and reproducible system to apply in this SL population. All cases were successfully classified with a high degree of inter-assessor agreement. Widespread establishment of a commonly adopted and clinically useful classification system will enable clinicians to improve patient selection as well as discussion with patient representatives during the decision-making process.

Evaluation of Dorsal Midline Discolorations with Physical Examination and Ultrasound

OBJECTIVE

To assess the association between dorsal midline skin discolorations, tethering of the spinal cord, and the role of ultrasound screening of these stigmata, focusing specifically on vascular lesions.

STUDY DESIGN

We conducted a prospective observational study of infants <6 months of age with suspicious dorsal midline skin stigmata. All were evaluated by physical examination and ultrasound scan. A subset also had a magnetic resonance imaging examination. We examined the association between small, red-shaded discolorations and their respective imaging findings.

RESULTS

Among 100 cases with discolorations of vascular types, either isolated or combined with low-risk simple dimples or deviated gluteal folds, none had clinically significant pathologic findings requiring surgical intervention.

CONCLUSIONS

Midline lumbar discolorations are more benign than previously thought. Despite the very low association of this group of stigmata with surgical implications, we still recommend the routine use of ultrasound scanning.

Putative height acceleration following tethered cord release in children

OBJECT

Tethered cord (TC) is a neurological disorder caused by tissue attachments that limit the normal movement of the spinal cord. A TC can be unmasked by a cutaneous abnormality or manifest clinically in myriad neurological, urological, and orthopedic symptoms. The relationship between TC and height is previously unknown. This study investigates the association between TC release and changes in height profiles in the pediatric population.

METHODS

Fifty-two children undergoing first-time TC release at a single institution were examined retrospectively. Clinical symptoms, radiographic findings, pre- and postoperative height, and height-for-age percentiles were recorded and analyzed.

RESULTS

Children with TC experienced a statistically significant increase in age-adjusted height percentiles after TC release (p = 0.0028), with a mean increase of 7 percentile points (from 48.1st to 54.9th percentile). When stratified by age, children 5 years or older (5-18 years) demonstrated a mean percentile increase of 10 percentile points (from 46.7th to 56.4th percentile) (p = 0.0001). Among the same age group, this effect scaled significantly with age (p = 0.02, beta coefficient -1.3). There was no significant difference in height-for-age after detethering surgery in children younger than 5 years. There was no significant association between the presence of clinical symptoms or specific radiographic findings and height outcomes after surgery. Overall, 56% of TC-related clinical symptoms improved after detethering (mean follow-up 4.6 months). Among children younger than 5 years, 82% of TC-related clinical symptoms improved after detethering (average follow-up 4.5 months); in children 5-18 years, 47% of symptoms improved after detethering (average follow-up 4.8 months).

CONCLUSIONS

The authors observed a statistically significant gain in height-for-age percentiles in children undergoing surgical release of TC. The authors' data suggest that such gains may be more significant in older children (≥ 5 years) and the increase appears to scale positively with youth in the older cohort. In this study, postoperative height gains did not appear to correlate with the presence of TC-related clinical symptoms or radiographic findings. Further investigation is necessary to elucidate any potential correlation between release of TC and height changes in children postoperatively.

Asymptomatic lumbosacral lipomas--a natural history study

BACKGROUND

Inevitable deterioration due to mechanical tethering is perceived as the natural history for complex congenital spinal lipomas of the conus medullaris region, even if asymptomatic at presentation. The conventional wisdom that prophylactic surgical untethering improves outcome has been challenged recently [1, 2]. This study examines the natural history of asymptomatic un-operated children with lumbosacral lipomas (LSL) and investigates whether predictive factors herald deterioration.

METHODOLOGY

Over the past decade, children presenting with complex LSL to a single clinician at Great Ormond Street Hospital (GOSH), London, UK have undergone a thorough assessment focusing on neurological and urological evaluation and MRI of the lumbosacral spine. For children deemed to be asymptomatic, conservative management has been adopted with close periodic surveillance of neurological and urological function, thus avoiding untethering surgery unless symptomatic deterioration occurs. A retrospective review identified this cohort of children asymptomatic of their LSL and their progress closely recorded.

DISCUSSION

This study suggests that the natural history of this subgroup of dysraphic patients may be more benign than hitherto considered. Conservative management with adoption of a novel surveillance policy and timely intervention only in the presence of symptomatic deterioration resulted in 71% of this series remaining clinically asymptomatic at mean follow up period of 5.9 years (range, 1.0-19.3 years). At 10 years, the cumulative risk of deterioration determined by the Kaplan-Meier method was 40%. Children aged<2 years, female, with presence of a transitional type of LSL and associated syrinx were independently associated with a higher risk of deterioration.

Tethered cord syndrome in adults

OBJECT

The treatment of tethered cord syndromes in adults is discussed regarding the natural history and surgical indications. The author analyzes data obtained in patients who were diagnosed with a tethered cord in adulthood and either underwent surgical or conservative therapy between 1991 and 2009.

METHODS

Since 1991, data obtained in 2515 patients with spinal cord pathologies were entered into the spinal cord database, and prospective follow-up was performed through outpatient visits and questionnaires. Of the 2515 patients, 85 adults with a tethered cord syndrome formed the basis of this study. The tethering effect was caused either by a split cord malformation, a thick filum terminale, a conus medullaris lipoma with extradural extension, or various combinations of these mechanisms. The mean age of the patients was 46 ± 13 years (range 23-74 years) and the mean follow-up duration was 61 ± 62 months. Two groups were distinguished based on the absence (Group A, 43 patients) or presence (Group B, 42 patients) of an associated lipoma or dysraphic cyst (that is, dermoid, epidermoid, or neurenteric cyst). Surgery was recommended for patients with symptoms only. Short-term results were determined within 3 months of surgery, whereas long-term outcomes (clinical recurrences) were evaluated using Kaplan-Meier statistics.

RESULTS

For all patients, pain was the most common major complaint. Severe neurological deficits were rare. In Group A, 20 of 43 patients underwent surgery, whereas in Group B 23 of 42 patients underwent surgery. Among individuals who did not undergo surgery, 17 patients refused surgery and 25 patients underwent recommended conservative treatment. Short-term postoperative results indicated a significant improvement of pain and a stabilization of neurological symptoms. Long-term results showed a good prognosis in patients in whom first-time (that is, nonrevision) surgery achieved successful untethering, with a 10-year rate of neurological stabilization in 89% of Group A and a 10-year rate of neurological stabilization in 81% of Group B patients. The benefit of secondary operations in Group B was limited, with eventual clinical deterioration occurring in all patients within 10 years. For patients treated conservatively, follow-up information could be obtained in 33 of 42 patients. Twenty-eight patients remained in stable clinical condition. Only 5 of the conservatively treated patients experienced clinical deterioration over time; in 4 of these individuals with deterioration, surgery had been recommended but was refused by the patient. The clinical recurrence rate in all conservatively treated patients was 21% after 10 years. With a recommendation for surgery this figure rose to 47% within 5 years.

CONCLUSIONS

Surgery in adult patients with a tethered cord syndrome should be reserved for those with symptoms. In surgically treated patients, pain relief can often be achieved, and long-term neurological stabilization tends to persist more often than it does in conservatively treated patients. A conservative approach is warranted, however, in adult patients without neurological deficits. Revision surgery in patients with complex dysraphic lesions should be performed in exceptional cases only.

Low-risk lumbar skin stigmata in infants: the role of ultrasound screening

OBJECTIVE

To reassess the utility and validity of ultrasound (US) screening in infants with lumbar midline skin stigmata (MSS) that may be associated with tethering of the spinal cord.

STUDY DESIGN

We conducted a prospective observational study of 254 infants under age 6 months with suspicious dorsal MSS between 2005 and 2007. All infants were examined by US and neurosurgical clinical evaluation, and 50 infants also underwent magnetic resonance imaging (MRI). The US and MRI findings were analyzed for correlation. Associations between the imaging findings and the presence of the low-risk skin lesions simple dimple (113 cases) and deviated gluteal fold (DGF; 44 cases) also were evaluated.

RESULTS

Analysis of US and MRI results for the cohort of 50 neonates in whom both examinations were performed showed high concordance. The low-risk group of infants with simple dimple and DGF constituted 157 US procedures, 96% of which were of high quality, providing clear visualization of spinal components. None demonstrated any clinically significant pathological findings.

CONCLUSIONS

Our data reaffirm the reliability of US as a screening tool for tethered cord syndrome. Infants with low-risk lesions, such as simple dimple and DGF, may be absolved from US screening, because these findings alone do not indicate underlying pathological lesions. We propose a simplified diagnostic classification system for MSS.

Association of Chiari malformation type I and tethered cord syndrome: preliminary results of sectioning filum terminale

OBJECTIVE

The pathogenesis of CM-I is incompletely understood. We describe an association of CM-I and TCS that occurs in a subset of patients with normal size of the PCF.

METHODS

The prevalence of TCS was determined in a consecutively accrued cohort of 2987 patients with CM-I and 289 patients with low-lying cerebellar tonsils (LLCT). Findings in 74 children and 244 adults undergoing SFT were reviewed retrospectively. Posterior cranial fossa size and volume were measured using reconstructed 2D computed tomographic scans and MR images. Results were compared to those in 155 age- and sex-matched healthy control individuals and 280 patients with generic CM-I. The relationships of neural and osseus structures at the CCJ and TLJ were investigated morphometrically on MR images. Intraoperative CDU was used to measure anatomical structures and CSF flow in the lumbar theca.

RESULTS

Tethered cord syndrome was present in 408 patients with CM-I (14%) and 182 patients with LLCT (63%). In 318 patients undergoing SFT, there were no significant differences in the size or volume of the PCF as compared to healthy control individuals. Morphometric measurements demonstrated elongation of the brain stem (mean, 8.3 mm; P < .001), downward displacement of the medulla (mean, 4.6 mm; P < .001), and normal position of the CMD except in very young patients. Compared to patients with generic CM-I, the FM was significantly enlarged (P < .001). The FT was typically thin and taut (mean transverse diameter, 0.8 mm). After SFT, the cut ends of the FT distracted widely (mean, 41.7 mm) and CSF flow in the lumbar theca increased from a mean of 0.7 cm/s to a mean of 3.7 cm/s (P < .001). Symptoms were improved or resolved in 69 children (93%) and 203 adults (83%) and unchanged in 5 children (7%) and 39 adults (16%) and, worse, in 2 adults (1%) over a follow-up period of 6 to 27 months (mean, 16.1 months +/- 4.6 SD). Magnetic resonance imaging 1 to 18 months after surgery (mean, 5.7 months +/- 3.8 SD) revealed upward migration of the CMD (mean, 5.1 mm, P < .001), ascent of the cerebellar tonsils (mean, 3.8 mm, P < .001), reduction of brain stem length (mean, 3.9 mm, P < .001), and improvement of scoliosis or syringomyelia in some cases.

CONCLUSIONS

Chiari malformation type I/TCS appears to be a unique clinical entity that occurs as a continuum with LLCT/TCS and is distinguished from generic CM-I by enlargement of the FM and the absence of a small PCF. Distinctive features include elongation and downward displacement of the hindbrain, normal position of the CMD, tight FT, and reduced CSF flow in the lumbar theca. There is preliminary evidence that SFT can reverse moderate degrees of tonsillar ectopia and is appropriate treatment for cerebellar ptosis after Chiari surgery in this cohort.

Three-dimensional constructive interference in steady-state magnetic resonance imaging in syringomyelia: advantages over conventional imaging

OBJECT

Neuroradiology has become indispensable in detecting the pathophysiology in syringomyelia. Constructive interference in steady-state (CISS) magnetic resonance (MR) imaging can provide superior contrast at the sub-arachnoid tissue borders. As this region is critical in preoperative evaluation, the authors hypothesized that CISS imaging would provide superior assessment of syrinx pathology and surgical planning.

METHODS

Based on records collected from a database of 130 patients with syringomyelia treated at the authors' institution, 59 patients were prospectively evaluated with complete neuroradiological examinations. In addition to routine acquisitions with FLAIR, T1- and T2-weighted, and contrast-enhanced MR imaging series, the authors obtained sagittal cardiac-gated sequences to visualize cerebrospinal fluid (CSF) pulsations and axial 3D CISS MR sequences to detect focal arachnoid webs. Statistical qualitative and quantitative evaluations of spinal cord/CSF contrast, spinal cord/CSF delineation, motion artifacts, and artifacts induced by pulsatile CSF flow were performed.

RESULTS

The 3D CISS MR sequences demonstrated a contrast-to-noise ratio significantly better than any other routine imaging sequence (p < 0.001). Moreover, 3D CISS imaging can detect more subarachnoid webs and cavitations in the syrinx than T2-weighted MR imaging with less flow-void artifact. The limitation of 3D CISS imaging is a susceptibility to motion artifacts that can cause reduced spatial resolution. Lengthy acquisition times for axial segments can be reduced with multiplanar reconstruction of 3D CISS-generated sagittal images.

CONCLUSIONS

Constructive interference in steady-state imaging is the MR sequence of choice in the preoperative evaluation of syringomyelia, allowing significantly higher detection rates of focal subarachnoid webs, whereas standard T2-weighted MR imaging shows turbulent CSF flow voids. Constructive interference in steady-state MR imaging enables the neurosurgeon to accurately identify cases requiring decompression for obstructed CSF. Motion artifacts can be eliminated with technical variations.