Can the conus medullaris in normal position be tethered?

Hidden cause of paralysis: tight filum terminale in spinal cord injury without radiographic abnormality

Objective

To explore the clinical characteristics and surgical treatment outcomes of spinal cord injury without radiographic abnormality (SCIWORA) in children.

Methods

A retrospective analysis was conducted on the clinical data of four children diagnosed with SCIWORA who were admitted to the Neurosurgery Department of Qingdao Women and Children's Hospital from November 2022 to June 2024. All four pediatric patients underwent laminectomy for spinal canal decompression along with resection of the filum terminale. Postoperatively, a regimen including corticosteroids and mannitol was administered. Following hospital discharge, each child was subjected to clinical follow-ups, and the neurological recovery from spinal cord injury was evaluated utilizing the American Spinal Injury Association (ASIA) impairment scale.

Results

Among the four patients, there was one male and three females, aged from 3 years and 2 months to 8 years. Two cases were due to low falls, one from a lower back injury, and one from a lumbar sprain. All patients had thoracolumbar injuries, with rapid progression of symptoms, including paralysis, sensory impairment, and urinary and fecal retention. Follow-up duration ranged from 3 to 24 months; three patients showed varying degrees of recovery in muscle strength and/or sensory function and bowel and bladder control, while one showed no improvement. One patient developed scoliosis and another presented with neurogenic bladder.

Conclusion

Tethered cord syndrome may be a potential underlying cause of SCIWORA. For children with SCIWORA accompanied by tethered cord syndrome, we recommend early surgical intervention to perform laminectomy and release the tethered cord, which may aid in the recovery of neurological function.

Total spine MRI for the preoperative evaluation of adolescent idiopathic scoliosis: part 1

Adolescent idiopathic scoliosis is a commonly encountered condition often diagnosed on screening examination. Underlying, asymptomatic neural axis abnormalities may be present at the time of diagnosis. At certain institutions, total spine MRI is obtained preoperatively to identify these abnormalities. We provide a framework for the radiologist to follow while interpreting these studies. In part 1, we discuss Arnold Chiari malformations, syringomyelia, and the tethered cord. In part 2, we focus on spinal cord tumors, dysraphisms, to include diastematomyelia, and vertebral anomalies.

Tethered spinal cord tension assessed via ultrasound elastography in computational and intraoperative human studies

BACKGROUND

Tension in the spinal cord is a trademark of tethered cord syndrome. Unfortunately, existing tests cannot quantify tension across the bulk of the cord, making the diagnostic evaluation of stretch ambiguous. A potential non-destructive metric for spinal cord tension is ultrasound-derived shear wave velocity (SWV). The velocity is sensitive to tissue elasticity and boundary conditions including strain. We use the term Ultrasound Tensography to describe the acoustic evaluation of tension with SWV.

METHODS

Our solution Tethered cord Assessment with Ultrasound Tensography (TAUT) was utilized in three sub-studies: finite element simulations, a cadaveric benchtop validation, and a neurosurgical case series. The simulation computed SWV for given tensile forces. The cadaveric model with induced tension validated the SWV-tension relationship. Lastly, SWV was measured intraoperatively in patients diagnosed with tethered cords who underwent treatment (spinal column shortening). The surgery alleviates tension by decreasing the vertebral column length.

RESULTS

Here we observe a strong linear relationship between tension and squared SWV across the preclinical sub-studies. Higher tension induces faster shear waves in the simulation (R2 = 0.984) and cadaveric (R2 = 0.951) models. The SWV decreases in all neurosurgical procedures (p < 0.001). Moreover, TAUT has a c-statistic of 0.962 (0.92-1.00), detecting all tethered cords.

CONCLUSIONS

This study presents a physical, clinical metric of spinal cord tension. Strong agreement among computational, cadaveric, and clinical studies demonstrates the utility of ultrasound-induced SWV for quantitative intraoperative feedback. This technology is positioned to enhance tethered cord diagnosis, treatment, and postoperative monitoring as it differentiates stretched from healthy cords.

Fetal neurosurgery

Among fetal surgical procedures, neurosurgery stands out due to the number of cases and the possibility of developing new procedures that can be performed in the fetal period. To perform fetal neurosurgical procedures, there is a need for specialized centers that have experts in the diagnosis of fetal pathologies and a highly complex obstetrics service with specialized maternal-fetal teams associated with a pediatric neurosurgery center with expertise in the diverse pathologies of the fetus and the central nervous system that offers multidisciplinary follow-up during postnatal life. Services that do not have these characteristics should refer their patients to these centers to obtain better treatment results. It is essential that the fetal neurosurgical procedure be performed by a pediatric neurosurgeon with extensive experience, as he will be responsible for monitoring these patients in the postnatal period and for several years. The objective of this manuscript is to demonstrate the diagnostic and treatment possibilities, in the fetal period, of some neurosurgical diseases such as hydrocephalus, tumors, occipital encephalocele, and myelomeningocele.

Fibrofatty filum terminale: long-term outcomes from a Singapore children's hospital

OBJECTIVE

The role of prophylactic detethering a fibrofatty filum terminale (FFT) remains equivocal. Furthermore, long-term studies focusing on urological outcomes are sparse. The aims of this study were to present an institutional experience on the perioperative and long-term outcomes of FFT surgery and to assess for factors that contribute to postoperative clean intermittent catheterization (CIC).

METHODS

This was a single-institution, retrospective study conducted over a 20-year period. Patients younger than 19 years of age who underwent surgery for FFT were included. Variables of interest included patient demographics, clinical presentation, radiological findings, postoperative complications, and long-term need for CIC. Outcomes were measured using the Necker functional score and modified Hoffer Functional Ambulation scale score at 3, 6, and 12 months postdischarge.

RESULTS

A total of 164 surgeries were performed for FFT from 2000 to 2020. The median age at surgery was 1.1 years, and the mean follow-up duration was 8.3 years. There were 115 patients (70.1%) who underwent prophylactic-intent surgery and 49 patients (29.9%) who underwent therapeutic-intent surgery. The proportion of therapeutic-intent surgeries increased significantly with age percentiles (0-20th, 21.9%; 20th-40th, 9.1%; 40th-60th, 18.2%; 60th-80th, 36.4%; and 80th-100th, 63.6% [p < 0.001]). Thirty patients (18.3%) had an associated syndrome, the most common (n = 19, 11.6%) being VACTERL (vertebral defects, anal atresia, cardiac defects, tracheo-esophageal fistula, renal anomalies, and limb abnormalities). Forty-eight patients (29.3%) had an associated malformation (anorectal anomaly = 37, urogenital anomaly = 16, and sacral anomaly = 3). Cutaneous manifestation was the most common presentation (n = 96, 58.5%), followed by lower-limb neurological deficits (n = 21, 12.8%). A low-lying conus was present in 36.0% of patients (n = 59), and 16.5% had an associated syrinx (n = 27). There were 26 patients (18.8%) with an abnormal preoperative urodynamic study. Three patients (1.8%) had postoperative complications that required repeat surgery. There were no cases of CSF leakage. One patient (0.6%) developed retethering requiring another surgery. Postoperative CIC was required in 11 patients (6.7%). Multivariable analyses showed that an abnormal preoperative urodynamic study (adjusted OR 5.5 [95% CI 1.27-23.9], p = 0.023) and having an intraspinal syrinx (adjusted OR 5.29 [95% CI 1.06-26.4], p = 0.042) were associated with the need for CIC.

CONCLUSIONS

The authors' results demonstrate that detethering surgery for FFT is a relatively safe procedure and can be performed prophylactically. Nonetheless, the risks of postoperative CIC should be emphasized during the preoperative counseling process.

Gestational age-specific reference standards of low-lying conus medullaris level in fetuses: a prospective cohort study

PURPOSE

To explore the position change of fetal conus medullaris by ultrasound, and to propose gestational age-specific references for the lower limits of fetal conus medullaris level.

METHODS

We prospectively collected the imaging and clinical data of fetuses whose mothers accepted routine prenatal ultrasonic follow-ups in the Department of Medical Ultrasonics, Chinese PLA General Hospital, between November 2020 and April 2021. By assigning to the conus medullaris levels, calculating statistical data, and performing linear regression analysis, we determined the correlation between the conus medullaris level and gestational week, as well as between the 95th percentile of the conus medullaris level, i.e., the lower limit of the conus medullaris level, and gestational week.

RESULTS

We included 1202 different fetuses at 17-40 gestational weeks in the study. Both the conus medullaris level and the 95th percentile of the conus medullaris level were linearly correlated with gestational week. We calculated the adjusted values of the lower limits of fetal conus medullaris levels, that is, the theoretical references of the lower limits, according to the linear regression equation, and composed a comparison table.

CONCLUSION

The fetal conus medullaris position continues changing cranially with gestational weeks during the whole pregnancy. The conus medullaris of a term fetus should not lie below the L2 vertebra level at birth. We proposed reference criteria of fetal low-lying conus medullaris for each gestational week from 17 to 40 weeks of gestational age, which potentially help prompt diagnosis and improve prognosis of fetal tethered cord syndrome.

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.

Determination of the normal conus medullaris level in term infants: the role of MRI in early infancy

OBJECTIVE

This study aimed to explore the migration process of the conus medullaris (CM) in early infancy using infant MRI and to evaluate the application of MRI for locating the infant CM level.

METHODS

The authors retrospectively analyzed the CM level on the lumbosacral MR images of 26 term infants aged < 3 months who were classified into three groups according to age. The authors numbered the CM level in each patient and analyzed the range and average of the CM level of the cohort. The authors studied the linear correlation between CM level and postnatal days with linear regression analysis, 1-way ANOVA, and the least significant difference test.

RESULTS

The CM level ranged from the superior border of the L1 vertebra to the top third of the L3 vertebra. About 96.2% of infants had CM higher than the superior border of the L3 vertebra. On average, CM was located between the L1-2 intervertebral disc and the inferior border of the L2 vertebra (mean ± SD score 1.64 ± 1.14). The three groups had no significant statistical difference in CM level (F = 1.071 and p = 0.359; groups 1 and 2, p = 0.408; groups 1 and 3, p = 0.170; groups 2 and 3, p = 0.755). CM level had no linear regression correlation with postnatal days within the first month (r2 = 0.061, F = 0.654, p = 0.438) or within the first 3 months (r2 = 0.002, F = 0.056, p = 0.816).

CONCLUSIONS

The CM level reaches the normal adult level by birth in term infants and does not ascend during childhood. On average, the CM was between the L1-2 intervertebral disc and the inferior border of the L2 vertebra in term infants. Considering the possibility of physiologically low-lying CM, the authors agree that normal CM is located above the L3 level in term infants and CM at the L3 level could be equivocal and should be investigated with other clinical data. The study data suggest that MRI is an accurate and valuable method for determining the CM level in term infants.

Effect of untethering on occult tethered cord syndrome: a systematic review

BACKGROUND AND OBJECTIVES

Despite the evident clinical, neurological, orthopedic, and urodynamic dysfunctions, neuroanatomic imaging is normal in patients with occult tethered cord syndrome (OTCS). Therefore, the diagnosis of OTCS can be very complex. In this regard, this systematic review aimed to determine the main clinical features (i.e. neurological, musculoskeletal, and urological abnormalities) and improvement rates of these symptoms in patients with OTCS after the section of the filum terminale (SFT).

MATERIALS AND METHODS

All the papers published in three electronic databases, namely Google Scholar, PubMed, and Web of Science, were searched for the purposes of this study. The searching process started on 15 October and lasted until 9 November 2020. Eventually, 10 reports were found about the clinical outcomes of SFT for the management of the OTCS.

RESULTS

The included studies were carried out on a total of 234 patients with OTCS, all of whom had undergone SFT. Evaluation of urologic symptoms revealed that 40-100% of patients with OTCS suffered from urinary instability. Moreover, its improvement rate after SFT was estimated at 59-100%. Evaluation of neurological symptoms indicated that 25-69% of patients with OTCS suffered from back/leg pain, And its improvement rate, the symptoms of back/leg pain of all patients were resolved or improved after SFT. Lower extremity weakness was found in 9-40% of patients with OTCS which was resolved or improved after SFT in about 25-100% of patients. Nevertheless, surgical indications for occult tight filum terminale syndrome remain controversial.

CONCLUSION

Although it seems that the SFT in OTCS patients is promising in treating neurologic, orthopedic and urological symptoms, usage of surgical untethering for patients with OTCS is a controversial issue. Clinical evaluation and urodynamic testing can be used to identify patients with OTCS. However, a multidisciplinary diagnostic work-up is strongly recommended for every child with OTCS.

Evaluation of the Filum Terminale in Hereditary Equine Regional Dermal Asthenia

The objectives of this study were to describe the anatomy, histology, and ultrastructure of the equine filum terminale (FT) and to describe the FT in hereditary equine regional dermal asthenia (HERDA), a model of human Ehlers-Danlos syndromes (EDS). Those humans suffer from tethered cord syndrome (TCS) caused by an abnormally structured FT wherein its attachment at the base of the vertebral column leads to long-term stretch-induced injury to the spinal cord. The pathophysiology of TCS in EDS is poorly understood, and there is a need for an animal model of the condition. Histopathologic and ultrastructural examinations were performed on FT from HERDA (n = 4) and control horses (n = 5) and were compared to FT from human TCS patients with and without EDS. Adipose, fibrous tissue, and neuronal elements were assessed. CD3 and CD20 immunohistochemistry was performed to clarify cell types (HERDA n = 2; control n = 5). Collagen fibrils were assessed in cross-section for fibril diameter and shape, and in longitudinal section for fibril disorganization, swelling, and fragmentation. The equine and human FT were similar, with both containing fibrous tissue, ependyma, neuropil, and nerve twigs. Hypervascularity was observed in both HERDA horses and human EDS-TCS patients and was not observed in equine or human controls. Moderate to severe abnormalities in collagen fibril orientation and architecture were observed in all HERDA horses and were similar to those observed in human EDS-TCS patients.

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.

Surgical volume of simple tethered spinal cord releases: review of a large pediatric neurosurgical service experience

OBJECTIVE

The aim of this study was to retrospectively review, from a single busy pediatric neurosurgical service, a consecutive series of patients who had undergone surgery for a simple tethered spinal cord, which was defined by a thickened or fatty filum terminale with a normal conus. The hope was to contribute to benchmark data regarding the expected frequency of surgery for this condition.

METHODS

The authors reviewed the electronic medical records of every patient with diagnosed simple tethered spinal cord, defined on spinal MRI as a thickened (> 2 mm in diameter) or fatty filum terminale, and who had undergone primary filum section at Boston Children's Hospital between 2005 and 2011.

RESULTS

A total of 208 patients met the study inclusion criteria. At the time of surgery, patients ranged in age from 0.4 to 19.8 years. One hundred forty-four (69%) patients were symptomatic with one or more of the following: bowel/bladder dysfunction, 94 (45%); neurological dysfunction, 49 (24%); scoliosis, 44 (21%); or back pain, 44 (21%). Sixty-four (31%) patients were asymptomatic and were operated on prophylactically when filum pathology was discovered during the course of a workup for clinical syndromes such as anorectal anomalies and/or suspicious cutaneous lesions. No patients in this series were operated on if they had normal MRI studies, defined as a conus tip no lower than L3 and no distal tethering lesion visualized. Over the study period, approximately 1000 major surgical cases were performed in the department every year, only 30 of which were simple detethering procedures, representing well under 5% of the service's operative volume and approximately 5 cases per surgeon per year. Clinical follow-up, available at a postoperative interval of 6.6 ± 3.8 years, demonstrated that approximately 80% of patients symptomatic with bowel or bladder involvement or neurological dysfunction had improvement or relief of their symptoms and that none of the patients treated prophylactically experienced new-onset symptoms that could be related to spinal tethering.

CONCLUSIONS

Simple detethering procedures were relatively uncommon in an active, well-established pediatric neurosurgical service and represented less than 5% of the service's total case volume per year with an average of 5 cases per surgeon per year. No patients with normal MRI studies were operated on during the study period.

Are high lumbar punctures safe? A magnetic resonance imaging morphometric study of the conus medullaris

A high lumbar puncture (LP) at L2-L3 or above is often necessary to consider on technical grounds, but complications of conus medullaris (CM) damage during high LP are potentially concerning. We hypothesized that a high LP might be safer than previously thought by accounting for movements of the CM upon patient positional changes. We retrospectively reviewed standard normal supine lumbar spine magnetic resonance imaging of 58 patients and used electronic calipers on axial images at the T12-L1, L1-L2, and L2-L3 disc levels to measure the transverse diameter of the CM relative to the size of the dorsal thecal sac space (DTSS) through which a spinal needle could be inserted. On 142 axial images, the means for CM diameters were 8.2, 6.0, and 2.9 mm at the three levels, respectively. We then used known literature mean CM displacement values in the legs flexed and unflexed lateral decubitus position (LDP) to factor in CM shifts to the dependent side. We found that at all three levels, the likely positional shift of the CM would be too small and insufficient to displace the entire CM out of the DTSS. However, if needle placement could be confined to the midsagittal plane, an LP in the unflexed LDP would theoretically be entirely safe at both L1-L2 and L2-L3, and almost so at L2-L3 in the legs flexed LDP. Thus, high LPs at L1-L2 and L2-L3 are in theory likely safer than considered previously, more so in the legs unflexed than in the flexed LDP. Clin. Anat. 32:618-629, 2019. © 2019 Wiley Periodicals, Inc.

Impact of magnetic resonance imaging and urodynamic studies on the management of sacrococcygeal dimples

OBJECTIVE Sacrococcygeal dimples in neonates and infants are of uncertain pathological import. Previously they were believed to be rarely associated with intraspinal anomalies. Recent studies using MRI, however, revealed that 6%-7% of pediatric cases of sacrococcygeal dimples were associated with anatomical tethered spinal cord (TSC). Because the prevalence of tethered cord syndrome is still unclear, there is no consensus among pediatric neurosurgeons on the management of children with sacrococcygeal dimples. The authors performed an analysis of MRI and urodynamic studies to validate their management strategy for pediatric cases of sacrococcygeal dimples. METHODS A total of 103 Japanese children (49 male and 54 female, median age 4 months, range 8 days-83 months) with sacrococcygeal dimples who were referred to the Division of Pediatric Neurosurgery between 2013 and 2015 were included in this study. The lumbosacral region of all the patients was investigated using MRI. Anatomical TSC was defined as a condition in which the caudal end of the conus medullaris is lower than the inferior border of the L2-3 intervertebral disc. Patients with minor spinal anomalies (e.g., anatomical TSC, filum lipoma, thickened filum, or filar cyst) underwent further urodynamic studies to ascertain the presence of neurogenic bladder (NGB). In this study, the presence of NGB without anatomical TSC but with other minor spinal anomalies was defined as "functional TSC." The prevalence of anatomical and functional TSC was investigated. The association of the following cutaneous findings with spinal anomalies was also assessed: 1) depth of the dimple, 2) deviation of the gluteal fold, and 3) other skin abnormalities (e.g., discoloration, angioma, or abnormal hair). RESULTS The children were classified into 4 groups: Group 1, patients with anatomical TSC; Group 2, patients with functional TSC; Group 3, patients without anatomical or functional TSC but with other minor spinal anomalies; and Group 4, patients with no spinal anomaly. There were 6 patients (5.8%) in Group 1, 8 patients (7.8%) in Group 2, 10 patients (9.7%) in Group 3, and 79 patients (76.7%) in Group 4. Twenty-four patients (23.3%; Groups 1, 2, and 3) showed MRI abnormalities, including filum lipoma (14 cases), filar cysts (5 cases), thickened filum (2 cases), and anatomical TSC without other spinal anomalies (3 cases). Untethering of the spinal cord was indicated for 14 patients (13.6%; Groups 1 and 2) with anatomical and functional TSCs. Preoperative NGB was found in 12 patients and improved postoperatively in 7 (58.3%). None of the associated lumbosacral skin findings predicted the presence of underlying spinal anomalies. CONCLUSIONS The prevalence of tethered cord syndrome among children with sacrococcygeal dimples was, for the first time, revealed to be higher than previously thought. MRI and supplemental urodynamic studies may be indicated for children with sacrococcygeal dimples to identify patients with symptomatic TSC.

Congenital and Hereditary Diseases of the Spinal Cord

Congenital anomalies of the spinal cord can pose a diagnostic dilemma to the radiologist. Several classification systems of these anomalies exist. Antenatal ultrasound and fetal magnetic resonance imaging is playing an increasingly important role in the early diagnosis and management of patients. Understanding the underlying anatomy as well as embryology of these disorders can be valuable in correctly identifying the type of spinal cord dysraphic defect. Hereditary spinal cord diseases are rare but can be devastating. When the onset is in adulthood, delay in diagnosis is common. Although the spine findings are nonspecific, some imaging features combined with brain imaging findings can be distinctive. Sometimes, the radiologist may be the first to raise the possibility of these disorders.

Does the position of conus medullaris change with increased thoracolumbar kyphosis in ankylosing spondylitis patients?

To date, only a few reports described the potential factors influencing the position of conus medullaris. One previous study revealed no significant change of conus locations in patients with idiopathic scoliosis; however, the effect of ankylosing spondylitis (AS)-related thoracolumbar kyphosis on conus position remains unexplored. Therefore, we aimed to investigate the variation of conus medullaris terminations in patients with thoracolumbar kyphosis secondary to AS when compared with normal subjects, and evaluated the relationship between conus positions and the magnitude of kyphosis. In this study, MR images of 96 AS patients with thoracolumbar kyphosis, including 86 males and 10 females with an average of 34.6 years (range, 17-65 years), and 100 age-matched normal controls were reviewed to determine the conus terminations in relation to spinal levels. Sagittal parameters of the AS group measured on radiograph included: global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), and thoracolumbar junction (TLJ). Finally, conus tips located at the mean level of the lower 3rd of L1 in both groups, there was no significant difference of the conus distributions between AS and control group (P = 0.49). In addition, conus medullaris displayed similar positions in AS patients among various apical region groups (P = 0.88), and no significant difference was found when AS population was stratified into GK ranges of 30° (P = 0.173). Also, no remarkable correlation of the conus positions with GK (r = -0.15, P = 0.15), TK (r = -0.10, P = 0.34), LL (r = -0.10, P = 0.32), and TLJ (r = -0.06, P = 0.54) was identified. This study showed the conus terminations displayed a wide range of distributions in AS patients with thoracolumbar kyphosis, which was similar to normal subjects. Moreover, the conus located at a relatively fixed position and would not be affected by the change of kyphosis magnitude, which is an important knowledge that surgeons should acquire in surgical correction of the deformity in these patients.

Conus Medullaris Level in Vertebral Columns With Lumbosacral Transitional Vertebra

BACKGROUND

The estimated prevalence of lumbar or sacral transitional vertebrae (LSTV) in the population is 4% to 30%. Few small patient series have studied the normal level of the conus medullaris (CM) in individuals with LSTV.

OBJECTIVE

To determine, by using a large cohort of patients, whether individuals of all ages with LSTV have different CM positions in the spinal canal in comparison with the rest of the population with normal vertebral columns.

METHODS

We performed an institutional retrospective analysis of spinal magnetic resonance images on individuals with LSTV of all ages, sexes, and pathologies during a 10-year period. Fifty-seven percent of patients (n = 467) had a lumbarized vertebra and 43% had sacralized vertebra (n = 355). Mean age at the time of the study was 55 ± 19 years (range 1-97 years). Fifty-two percent were male and 48% were female. Sixty percent of subjects with a sacralized vertebra were female, and 54.5% of those with a lumbarized vertebra were male (P = .001).

RESULTS

The CM in individuals with a lumbarized vertebra was seen to be lower at L1-2 to L2s, than un those with a sacralized vertebra where most conuses were at T12-L1 to L1s (P ≤ 0.001). The CM level was similarly distributed among sexes and ages.

CONCLUSION

In our series, the CM level, when lumbarization occurred, was lower, with a mean level at L1-L2, whereas a more superior mean level at T12-L1 was seen when sacralization occurred. CM level was not influenced by sex, age, or pathology other than tethered cords.

Occult spinal dysraphism: lessons learned by retrospective analysis of 149 surgical cases about natural history, surgical indications, urodynamic testing, and intraoperative neurophysiological monitoring

PURPOSE

Prophylactic surgery is indicated for lipoma of the filum, while it is still debated for the conus lipomas and more complex tethering malformations of the cord.

METHODS

We retrospectively reviewed the preoperative and postoperative clinical histories and long-term outcomes of 149 operated patients (33 adults, 116 children). Intraoperative neurophysiological monitoring (NPM) was utilized since 1998. Their malformative lesions were reclassified following recent Pang's embryological criteria for surgical complexity. In nine cases, the spinal tethering malformation was associated with an anorectal malformation (ARM) and in nine with a Chiari I malformation (CM1).

RESULTS

One hundred nineteen (80 %) patients were symptomatic at the time of surgery, 66 (44 %) having presented with progressive preoperative deterioration. Postoperative surgery-related deterioration was observed in 6 % of the cases operated on under the intraoperative NPM control. Surgery did not improve any deficit, especially of sphincter functions, independently from the type of associated malformation (ARM, CM1). Urodynamic testing was a reliable predictor both in the preoperative and in the follow-up period of subsequent neurological deterioration. In the long-term follow-up, an increasing percentage of retethering was observed, especially concerning complex cases submitted to partial excision. The surgical risk increased with repeated operations.

CONCLUSIONS

This study demonstrates that the rate of the natural deterioration associated with a conservative approach is higher than in patients operated on prophylactically, if the operation is performed by a team with a special expertise. However, the first surgical procedure should be aimed at detethering the conus completely, with the aid of intraoperative NPM; even in expert hands, it is associated with a high risk of clinical deterioration. Based on these results, we are increasing the percentage of children to whom surgery is offered when still asymptomatic as well as the degree of the lipoma excision to prevent retethering. However, in cases of rethetering and subjects presenting in adult age, we suggest to consider for surgery only those symptomatic. Urodynamic testing and magnetic resonance imaging in prone position were, in our experience, the best tools for screening those patients at risk of symptomatic retethering.

Section of the filum terminale: is it worthwhile in Chiari type I malformation?

A section of the filum terminale (SFT) is used for the surgical treatment of isolated tethered cord or that resulting from neurulation disorders. More recently, it has been proposed for the management of the occult tethered cord syndrome (OTCS), though it is still under debate. Even more controversial appears to be the use of SFT in patients with Chiari type I malformation (CIM), which is based on the possible presence of OTCS. This review shows that: (1) there are issues both in favor and against the occurrence of OTCS, (2) there is no significant correlation between CIM and tethered cord, the old "caudal traction theory" being not supported by clinical or experimental evidences. On these grounds, a relationship between CIM and OTCS is hard to be demonstrated, (3) a subgroup of patients with CIM suffering from OTCS may exist and benefit from SFT.

Tethered cord: natural history, surgical outcome and risk for Chiari malformation 1 (CM1): a review of 110 detethering

The surgical results of this series of occult spina bifida seem better than the natural history registered in the long pre-operative period in terms of neurological deterioration. The major contribution to this result is attributed to neurophysiological monitoring that lowers the risks of permanent damage and increases the percentage of effective detethering. The present series of TCS, due to conus and filar lipoma, documents that CM1 is a really rare association occurring in less than 6% of the patients, despite the low position of conus. The detethering procedure did not influence the tonsillar position, thus excluding the correlation between the tethering and the tonsillar descent. The genetic alteration documented in a girl reinforces the hypothesis of a rare complex polymaformative picture deserving multiple procedures according to the prevailing clinical symptoms.

Dysfunctional voiding: A review of the terminology, presentation, evaluation and management in children and adults

Dysfunctional voiding (DV) is a voiding disorder characterized by dyssynergic striated sphincteric activity in the absence of a proven neurological etiology. It can present at any age with a spectrum of storage and voiding symptoms that may resemble florid neurogenic bladder. There is a striking lack of clarity regarding what this entity represents, the diagnostic methodology and treatment. The limitations of existing guideline documents are analyzed. Specifically, use of the term "habitual", the assumption that bladder changes are secondary to the outlet, the emphasis on "staccato" voiding and the implication of striated urethral sphincter are discussed. Literature shows that DV may also present with continuous slow flow or normal flow. Dyssynergia may be at the level of the striated urethral sphincter, the pelvic floor or both, better termed "striated urethral sphincter-pelvic floor complex" (SUS-PFC).A diagnostic algorithm is provided so that patients are evaluated on merit rather than on the basis of different philosophies of individual centers. High-risk markers such as hydronephrosis, vesicoureteral reflux, renal failure or marked voiding difficulty should prompt a formal urodynamics evaluation and imaging for neurological etiology. Patients with predominantly storage symptoms with incidental staccato voiding can be managed initially, on the basis of non-invasive evaluation. Conservative urotherapy including biofeedback is appropriate initial management for patients without high risk factors. Treatment and evaluation should be escalated based on response. Patients with severe DV will need treatment similar to neurogenic bladder including clean intermittent catheterization and measures to control storage pressures.

Chiari type I malformation in children

The diagnosis of Chiari type I malformation (CIM) is more and more frequent in clinical practice due to the wide diffusion of magnetic resonance imaging. In many cases, such a diagnosis is made incidentally in asymptomatic patients, as including children investigated for different reasons such as mental development delay or sequelae of brain injury. The large number of affected patients, the presence of asymptomatic subjects, the uncertainties surrounding the pathogenesis of the malformation, and the different options for its surgical treatment make the management of CIM particularly controversial.This paper reports on the state of the art and the recent achievements about CIM aiming at providing further information especially on the pathogenesis, the natural history, and the management of the malformation, which are the most controversial aspects. A historial review introduces and explains the current classification. Furthermore, the main clinical, radiological, and neurophysiological findings of CIM are described to complete the picture of this heterogeneous and complex disease.

Spinal cord traction, vascular compromise, hypoxia, and metabolic derangements in the pathophysiology of tethered cord syndrome

OBJECT

The definition of tethered cord syndrome (TCS) relies mainly on radiological criteria and clinical picture. The presence of a thickened filum terminale and a low-lying conus medullaris in symptomatic patients is indicative of TCS. The radiological definition of TCS does not take into account cases that involve a normal-lying conus medullaris exhibiting symptoms of the disease.

METHODS

The authors performed a MEDLINE search using the terms "tethered cord" and "pathophysiology." The search returned a total of 134 studies. The studies were further filtered to identify mostly basic research studies in animal models or studies related to the biomechanics of the filum terminale and spinal cord.

RESULTS

Spinal cord traction and the loss of filum terminale elasticity are the triggers that start a cascade of events occurring at the metabolic and vascular levels leading to symptoms of the disease. Traction on the caudal cord results in decreased blood flow causing metabolic derangements that culminate in motor, sensory, and urinary neurological deficits. The untethering operation restores blood flow and reverses the clinical picture in most symptomatic cases.

CONCLUSIONS

Although classically defined as a disease of a low-lying conus medullaris, the pathophysiology of TCS is much more complex and is dependent on a structural abnormality, with concomitant altered metabolic and vascular sequelae. Given the complex mechanisms underlying TCS, it is not surprising that the radiological criteria do not adequately address all presentations of the disease.

Infant craniospinal ultrasonography: beyond hemorrhage and hydrocephalus

Ultrasonography is widely used for screening for neonatal intracranial hemorrhage, hydrocephalus, and cord tethering in young infants. Proper interpretation of infant cranial and spinal ultrasound examinations requires not only familiarity with the appearances of these disorders, but also recognition of imaging artifacts capable of mimicking pathology and awareness of developmental variants and conditions that occupy a borderline position along the spectrum from normal to abnormal. This article will review the current understanding of the ultrasonographic characteristics and clinical relevance of these imaging artifacts, developmental variants, and quasi-pathologic conditions to avoid diagnostic pitfalls and guide appropriate patient management.

Intractable voiding dysfunction in children with normal spinal imaging: predictors of failed conservative management

OBJECTIVES

To identify the factors that might predict which individuals ultimately fail to resolve voiding symptoms by analyzing their presenting symptoms and video-urodynamic findings. Older children with intractable voiding dysfunction and no evidence of neurologic abnormality, who are recalcitrant to medical treatment, pose a management challenge.

METHODS

The charts of neurologically normal children with intractable voiding dysfunction, who had fluorourodynamic studies and normal lumbosacral magnetic resonance imaging, were reviewed. A database was created that included the urodynamics, presenting urinary symptoms, presence of soiling or constipation, age at onset of symptoms, cystogram and bladder ultrasound findings, and treatments given. Long-term follow-up was determined from chart review (all patients) or by a mailed survey (15 patients). Patients without symptoms and off medication were defined as normal.

RESULTS

A total of 50 children met the criteria mentioned earlier in the text, presented at a mean age of 9.4 years (range, 3.8-17.3) and were followed up for a mean of 4 years (range, 1-11) from their initial urodynamic evaluation. Of them, 33 (66%) remained symptomatic and 1 (34%) normalized. A total of 31 were found to have uninhibited bladder contractions (UBCs) with daytime wetting, of which 24 (77.4%) failed to normalize (P = .037). All 9 with UBCs and detrusor-sphincter dyssynergia remained symptomatic (P = .02).

CONCLUSIONS

The majority failed to resolve their voiding symptoms. Children who presented with daytime wetting, UBC, and detrusor-sphincter dyssynergia were the most likely to remain symptomatic. Patients with these characteristics might be considered for more aggressive alternative therapies, after a period of medical management.

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.

Preoperative predictors for improvement after surgical untethering in occult tight filum terminale syndrome

BACKGROUND/AIMS

An occult tight filum terminale syndrome has been described wherein clinical symptoms result from tension on the spinal cord despite nondiagnostic spinal magnetic resonance imaging (MRI). Recent reports have suggested a role for surgical untethering in this patient population; however, controversy remains regarding the surgical treatment of this condition. Owing to the various clinical presentations, the relationship of presenting signs and symptoms to postoperative outcomes might be useful in surgical selection.

METHODS

A retrospective review was conducted of 22 pediatric cases of surgical untethering for suspected occult tight filum terminale syndrome. All patients had nondiagnostic MRI findings, defined as a conus medullaris above the L(3) vertebral body and a filum terminale diameter of less than 2 mm. Preoperative symptoms, signs and urodynamic test results were collected and compared with surgical outcomes determined by clinical notes and postoperative urodynamics reports. Abnormal findings on presentation were categorized as dermatologic, urologic, orthopedic and neurologic.

RESULTS

Patient age ranged from 7 months to 17 years, and 12 were female. Sixteen (73%) patients experienced subjective and/or objective improvement following surgical untethering. Fourteen patients had abnormal preoperative urodynamic testing, of which 12 underwent postoperative urodynamic testing. Five of these 12 (42%) demonstrated objective improvement postoperatively. Patients presenting with abnormal findings in at least 2 categories were more likely to improve following untethering (88%) than those with abnormalities in only 1 category (20%; p = 0.009).

CONCLUSION

Spinal cord untethering is a treatment option for occult tight filum terminale syndrome. Further evaluation of the relationship between preoperative findings and surgical outcomes may facilitate the selection of surgical candidates.

Tethered cord syndrome

Tethered cord syndrome is a clinical phenomenon resulting from anatomic restriction of the normal movement of the spinal cord or vascular compromise leading to hypoxia of its distal structures. Tethering can be acquired (secondary) or congenital (primary). This article presents the relevant embryology, primary and secondary causes of tethering, clinical presentations, the treatment of specific entities, indications and options for Tethered cord syndrome is a clinical phenomenon resulting from anatomic restriction of the normal movement of the spinal cord or vascular compromise leading to hypoxia of its distal structures. Causes of tethering can be acquired (secondary) or congenital (primary). This article presents the relevant embryology, primary and secondary causes of tethering, clinical presentations, the treatment of specific entities, indications and options for surgical treatment, and surgical complications.

Tethered cord syndrome in children: a review

✓The treatment of a patient with symptoms of a tethered spinal cord and in whom a fatty infiltrated terminal filum is found is controversial. The authors review their experience and the literature regarding this aspect of occult spinal dysraphism. From experience, transection of a fatty terminal filum in patients with symptoms related to excessive caudal cord tension is a minor procedure that generally yields good results. The most problematic issue in the literature is what patients and symptoms are best suited to surgical treatment.

Minimal tethered cord syndrome: what's necessary to justify a new surgical indication?

✓Traditionally, surgical division of the terminal filum (filum terminale) has been reserved for patients with imaging-apparent spinal cord tethering. The occurrence of medically refractory voiding dysfunction of neurogenic origin, without magnetic resonance (MR) imaging documentation of abnormality in the spine, has been termed “minimal” tethered cord syndrome (TCS). The rationale for and utility of using surgical division of the terminal filum in the treatment of minimal TCS are unproven.

Six studies that involved surgical division of the terminal filum for minimal TCS were identified and reviewed. A seventh study conducted prior to the MR imaging era, in which authors used myelography, was also included. In addition, two investigations of the clinicopathological findings in such cases were analyzed. A tripartite criterion for justifying the introduction of a new surgical indication is proposed and analyzed in light of this evidence.

In children with minimal TCS there are definite pathological changes in the terminal filum that are not visible on routine spinal MR imaging. These changes suggest that the pathophysiology of minimal TCS, like TCS that is demonstrated on neuroimaging, may involve abnormal traction on the distal spinal cord. Additional data are needed regarding the sensitivity and specificity of various clinical studies intended to identify children with minimal TCS. All existing data supporting the efficacy of surgery for minimal TCS have been generated by Class III studies. Clinical equipoise exists for this surgical indication, and, therefore, a prospective randomized trial should be completed.

Neuropathology of developmental abnormalities

Varieties of neuropathological disorders are caused by a perturbation of normal developmental processes, resulting from insults by heterogeneous etiologic factors. These factors trigger the sequence of molecular, biochemical, and morphologic alterations of the brain, resulting morphologically and/or functionally abnormal brain. The resulting brain contains basic components of the normal brain but is assembled in an abnormal way. The developmental stage when the insults occur appears to largely dictate the outcome of the pathological processes. Depending on the developmental stage involved, the morphology of the brain may be grossly abnormal or is apparently normal but functionally abnormal. The brain development progresses in an orderly fashion and can be divided into several major developmental stages; the neurulation (neural tube formation), ventral induction (formation of prosencephalon), neuroepithelial cell proliferation and migration, neuroglial differentiation and establishment of neuronal circuits. The perturbation of these developmental stages results in uniquely specific pathological outcome, regardless of the etiologic factors/agents. In this review, I will briefly discuss the normal pattern of brain development and neuropathology of the representative disorders resulting from the deviation of normal developmental processes in the individual developmental stage.

Treatment of the Occult Tethered Spinal Cord for Neuropathic Bladder: Results of Sectioning the Filum Terminale

PURPOSE

Occult tethered cord syndrome applies to patients with signs and symptoms consistent with a caudal spinal cord malformation despite normal neuroimaging. Although several reports of successful surgical treatment exist, controversy remains with respect to patient selection and efficacy. We present a large series with excellent clinical followup, neuroimaging and urodynamic characterization.

MATERIALS AND METHODS

We present our experience with 36 patients at a single institution with preoperative clinical findings, neuroimaging and urodynamics available. Postoperative outcomes were assessed clinically and with urodynamics. We determined predictive parameters to improve patient selection.

RESULTS

Approximately 0.04% of pediatric urology clinic visits resulted in neurosurgical referral for the potential of an occult tethered cord. They occurred after failure of a mean of 2 years of aggressive medical management. Daytime urinary incontinence was present in 83% of patients and 47% had encopresis. Preoperative urodynamics were markedly abnormal in all patients with mean bladder capacity 55% of expected capacity. Clinical improvement in urinary symptoms was seen in 72% of patients with resolution of incontinence in 42%. Bowel symptoms improved in 88% of cases, including resolution of encopresis in 53% within 3 months of surgery. Urodynamic improvements were demonstrated in 57% of cases. We were unable to determine preoperative factors that were more likely associated with surgical success.

CONCLUSIONS

In a highly select population with severe urinary and fecal dysfunction sectioning a normal-appearing filum terminale can result in significant improvement. We were unable to identify factors that may increase the chance of surgical success.