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Abstract
Spinal lipoma is one of the congenital abnormalities that affects the spinal cord. The suffix ‘oma’ is used to described a neoplastic event involving in pathophysiology of a lesion. Filum terminale has been termed “The unpaired nerve”, because it is what remains of the spinal cord at the end of the coccyx, was described by Galen. The prevalence of the disease remains unknown. Filum lipoma is a simple close dysraphism without any subcutaneous mass. It occurs because of an abnormality of secondary neurulation. Filum lipoma is benign, overgrowth of fat cells. In normal adults, the incidental fat within filum terminale is about 17%. The most commonly recorded symptoms include pain, sensory disturbance, weakness, and urinary disturbance. The test of choice would of course be magnetic resonance imaging (MRI). It has been suggested that the threshold of diagnosis of thickened filum is 2 mm. The classification of FL is based on whether the conus medullaris is at a normal age-specific position or not in addition to the presence of symptoms (neurological manifestations). Surgical intervention is the choice. Generally, symptomatic patients with low-lying conus medullaris should undergo detethering procedure. This is done by sectioning the thickened filum terminale which interrupts the connection between the conus medullaris and fat-infiltrated and hypertrophied filum. Overall, filar lipoma is considered a benign disease. Its treatment, especially the prophylactic method, carries significantly better prognosis with low complication rate.
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Spinal dysraphisms (SDs) are congenital malformations of the spinal cord, determined by derangement in the complex cascade of embryologic events involved in spinal development. They represent a heterogeneous group ranging from mild clinical manifestations-going unnoticed or being discovered at clinical examination-to a causal factor of life quality impairment, especially when associated with musculoskeletal, gastrointestinal, genitourinary, or respiratory system malformations. Knowledge of the normal embryologic development of the spinal cord-which encompasses three main steps (gastrulation, primary neurulation, and secondary neurulation)-is crucial for understanding the pathogenesis, neuroradiologic scenarios, and clinical-radiologic classification of congenital malformations of the spinal cord. SDs can be divided with clinical examination or neuroradiologic study into two major groups: open SDs and closed SDs. Congenital malformations of the spinal cord include a wide range of abnormalities that vary considerably in imaging and clinical characteristics and complexity and therefore may represent a diagnostic challenge, even for the experienced radiologist. Online supplemental material is available for this article.©RSNA, 2021.
Lumbosacral lipomas are the most common form of occult spinal dysraphism. The development of lumbosacral lipomas is from the premature disjunction of the neural tube from the surrounding ectoderm, leaving the neural plate open posteriorly and allowing for the infiltration of mesodermal tissue, including fatty tissue. Since lumbosacral lipomas are a common cause of spinal cord tethering that can lead to progressive neurological deficits, prophylactic neurosurgery for lumbosacral lipomas, including untethering of the spinal cord, is recommended. We briefly review the embryology, classification, clinical presentation, imaging evaluation, surgical indication, neurosurgical management and pathological examination that are involved in recognizing these complicated malformative pathologies.
Congenital lumbosacral lipomas can be responsible for progressive defects. The general feeling is that tethering of roots,
filum, or cord probably explains this evolution, and that untethering of these structures could prevent late deterioration.
Like the vast majority of neurosurgeons, we too have routinely and systematically operated on lumbosacral lipomas, even in
the absence of neurological deficits. This policy stemmed from our belief that spontaneous neurological deterioration was
frequent, recovery from preoperative deficits rare, and surgery both efficient and benign in nature. After 22 years of experience,
we felt that it was necessary to review our series of 291 lipomas (38 lipomas of the filum and 253 of the conus) operated
on from 1972 to 1994. To reassess the value of pro-phylactic surgery, we attempted an accurate evaluation of (1) the risk
of pathology, (2) the risks involved in surgery, (3) the postoperative outcome with respect to preoperative deficits, and
(4) the postoperative outcome in asymptomatic patients at 1 year and at maximum follow-up. Special attention was paid to 93
patients whose postoperative follow-up was more than 5 years (average 8.7, median 8, range 5–23 years). Of these 93 patients,
39 were asymptomatic preoperatively (7 with lipoma of the filum and 32 with lipoma of the conus). Lipomas of the filum and
of the conus are entirely different lesions and were studied separately. In 6 cases prenatal diagnosis had been possible.
The mean age at surgery was 6.4 years. Low back skin stigmata were present in 89.4% of cases. Preoperative neurological deficits
existed in 57% of the patients and were congenital in 22%. Clinical signs and symptoms recorded were pain in 13.3% of the
patients and/or neurological deficits affecting sphincter (52%), motor (27.6%) and sensory (22.4%) functions. Deficits were
progressive in 22.4% of cases, slowly progressive in 58.8% of these and rapidly progressive in the remaining 41.2%. In 36
patients (13.2%) the lipomas were seen to grow either subcutaneously or intraspinally. Among these patients, 21 were infants,
2 were obese adolescents, and 10 were pregnant women. The metabolism of the fat within the lipomas was studied in 11 patients
and found to be similar to that at other sites. Lipomas were associated with various other malformations, either intra- or
extraspinal. These associated anomalies were rare in the case of lipomatous filum (5.2%) but frequent with lipomas of the
conus, except for intracranial malformations (3.6%). Therapeutic objectives were spinal cord untethering and decompression,
sparing of functional neural tissue and prevention of retethering. Procedures used to achieve these goals were subtotal removal
of the lipoma, intraoperative monitoring, duroplasty, and sometimes closure of the placode. Histologically, lipomas consisted
of normal mature fat. However, 77% of them also included a wide variety of other tissues, originating from ectoderm, mesoderm,
or entoderm. This indicates that lipomas are either simple or complex teratomas. The results of the study are as follows.
(1) Surgery was easy and safe when performed for treatment of lipomas of the filum (no complications), but difficult and hazardous
in the case of lipomas of the conus (20% local, 3.9% neurological complications). (2) All types of deficit could be improved
by surgery, which was beneficial in all cases of lipoma of the filum and 50% of cases of lipoma of the conus. (3) In asymptomatic
patients long-term surgical results depended on the anatomical type of the lipoma. They were excellent in lipomas of the filum.
In lipomas of the conus they were good in the short term but eroded with time. At more than 5 years of follow-up only 53.1%
of the patients were still free of symptoms. (4) Reoperations were performed in 16 patients (5.5%), 5 (31.2%) of whom improved
postoperatively, while in 7 (43.7%) progression stopped, in 3 (18.7%) deterioration continued and in 1 (6.2%) the condition
was worse after surgery. (5) The natural history of the malformation, that is to say the risk of spontaneous aggravation,
has only been evaluated in hospital in-patients, so that the true level of risk remains unknown. This means we cannot interpret
the actuarial curve following surgery for asymptomatic lipoma of the conus. In conclusion, there are two different types of
lipoma: lipoma of the filum, for which surgery is harmless and beneficial in both the short and the long term, and lipoma
of the conus, for which surgery involves considerable risks and is of questionable benefit in the long term. This raises the
question as to whether prophylactic surgery is indicated for patients with asymptomatic lipomas of the conus, and whether
the outcome is any better than it would be if the lipoma were left to take its natural course. The lack of basic information
remains a stumbling block to management of these patients. Until this is remedied, we are unable to recommend prophylactic
surgery in patients with asymptomatic lipomas of the conus.
Lipomas of the spinal cord are among the most fascinating lesions encountered by the pediatric neurosurgeon. An understanding of spinal lipomas may, however, be difficult because the terminology used to describe the accumulations of spinal fat is confusing, inconsistently applied, and at times contradictory. An anatomical characterization of lipomas may assist in understanding these lesions. Lipomas of the spinal cord are very rare and cause symptoms related to mass effect and secondary compressive myelopathy. Lipomas of the conus medullaris (or lipomyelomeningocele) are the most common form of fatty masses in the spine and can be divided into dorsal, caudal, and transitional forms. These lesions are a manifestation of occult spinal dysraphism and a common cause of the tethered cord syndrome (TCS). The natural history of untreated lipomyelomeningocele, although incompletely understood, appears to be progressive neurological deterioration with loss of bladder control. Timely, careful surgical intervention may prevent significant neurological deterioration and progressive disability in the majority of children harboring these lesions. In surgical intervention the surgeon seeks to disrupt the connection between the fibrofatty mass and underlying cord as well as to reestablish normal anatomical planes. Several intraoperative video segments illustrating lipomyelomeningocele resection are included in this paper. Lipomas of the terminal filum (fatty filum) are truly occult and are also associated with TCS. Surgical treatment of filum lipomas carries significantly lower risk than that for lipomas of the conus medullaris. Again, the goal of surgery is to disrupt the connection between the abnormal fibrofatty tissue and the underlying spinal cord.
This book documents the state of the art in pediatric neurosurgery with the intention of providing a comprehensive guide to the management of the full range of pediatric neurosurgical disorders that will aid in the delivery of optimal care. Detailed practical instruction, taking into account recent advances, is provided on the neurosurgical treatment of congenital brain malformations, cerebrovascular diseases, head injuries and spinal trauma, infections, functional disorders, congenital and developmental spinal disorders, and brain and spinal tumors. Pearls and pitfalls are highlighted, and attention drawn to the most useful tips and tricks. Information is also included on relevant related topics, including the principles of neuroimaging, the physiological responses of newborns, infants, and children to neurosurgical trauma, preoperative evaluation, anesthesiology and intensive care, and other forms of therapy. The authors are renowned experts in the field, and the text is supported by a wealth of high-quality images. Handbook of Pediatric Neurosurgery will be of value for neurosurgeons of all levels of experience, as well as for pediatricians, neuroradiologists, neuropathologists, and neuro-oncologists.
This volume covers the known details of all subtypes of occult spinal dysraphism in unprecedented detail. This 21 chapter invaluable resource begins with a deep dive into the history and embryology of occult spinal dysraphisms. Following this, subtypes of occult spinal dysraphism are thoroughly explored — of which include split cord malformations, tethered cord syndromes, adult presentations/outcomes of occult spinal dysraphism, cutaneous stigmata. Chapters will cover the clinical presentation, radiological features, and surgical nuances of each of the occult spinal dysraphisms. Throughout the book, expertly written text is supplemented by a number of high quality figures and tables, as well as a video documenting surgical treatment of type 1 split cord malformation.
By focusing on each entity currently grouped within this topic as a separate chapter, the most up-to-date information will be provided to the reader, making Occult Spinal Dysraphism a must-have resource for students, practitioners and medical professionals involved in treating spinal dsyraphism.
Congenital abnormalities of the spine and spinal cord are referred to as spinal dysraphisms. This article reviews normal embryological development of the spine and spinal cord and the imaging findings of congenital abnormalities of the spine and spinal cord with particular focus on MRI.
31 children with spina bifida occulta who have presented with back pain, scoliosis, a progressive neurological deficit involving lower limbs or a neurogenic bladder have been found to have a tethered spinal cord. Release of the tethered spinal cord has always relieved pain, frequently occrected a progressive scoliosis, and arrested or improved neurogenic foot deformities as well as neurogenic bladder.
The prevalence and appearance on MRI of lipomas of the filum terminale was studied in a random population referred to MRI for evaluation of the lumbosacral spine. The MRI scans of 100 patients selected at random were retrospectively reviewed.
The study sought to determine the frequency and MRI appearance of incidental filum lipomas in a random population.
Postmortem studies have reported a 4%-6% incidence of occult fibrolipomas of the filum terminale in what were thought to be otherwise normal spinal cords. The improved resolution of MRI imaging allows the detection of small amounts of fat associated with the filum terminale that heretofore had not been demonstrated on radiologic imaging examinations.
The lumbosacral spine unenhanced MRI scans of 100 patients not previously operated upon were selected at random and were retrospectively reviewed by two of the authors (EB and JCM).
Of the 100 MRI examinations reviewed, four patients were found to have small lipomas of the filum terminale. No spinal dysraphism or cord tethering were present in these four patients. Their clinical symptoms were related to disc herniation in two patients, spinal stenosis in one, and discitis in one. The lipomatous tissue was hyperintense to cerebrospinal fluid (CSF) on T1-weighted images and hypointense to CSF on T2-weighted images.
Incidental lipomas of the filum terminale were present in 4% of 100 lumbosacral spine MRI examinations in a random population.
To determine the usefulness of urodynamic studies in the management of children with a suspected tethered spinal cord, the authors retrospectively reviewed case records of 25 patients evaluated both pre- and postoperatively using this diagnostic adjunct. All patients were also evaluated with magnetic resonance imaging or computerized tomography myelography. Seven patients who presented initially with orthopedic deformity, skin stigmata, and neurological problems underwent primary cord untethering (Group 1). All seven patients were urologically asymptomatic; all but one had normal findings on urodynamic study. Eighteen patients with prior myelomeningocele closure underwent secondary untethering (Group 2). They presented with urological (11 cases), neurological (three cases), or both urological and neurological (four cases) deterioration. All patients underwent surgery via a microsurgical technique. At a mean follow-up time of 2 years, the only Group 1 patient with preoperative abnormal urodynamic findings normalized following untethering, whereas another asymptomatic patient showed worsened results on his postoperative study. In Group 2, all seven patients with preoperative neurological deterioration improved. Ten of the 15 patients who had isolated or associated preoperative clinical urological deterioration improved or stabilized, whereas five displayed continued deterioration in their bladder function. With respect to urodynamic studies, there was a significant increase in total and pressure-specific bladder capacities following untethering. We conclude that urodynamic studies are useful both diagnostically and in follow-up examinations of patients with tethered cord, that disturbances identified by these studies often precede clinical manifestations of deterioration, and that spinal cord untethering favorably influences the urological status in most patients.
Spinal lipomas are a common cause of spinal cord tethering. Recently, prophylactic surgical removal of spinal lipomas has been questioned, especially of the conus medullaris. Unfortunately, few statistically significant series have been reported. A total of 213 children with spinal lipomas were operated on at the Children's Memorial Hospital in Chicago, Ill., USA, on whom 270 procedures were carried out between 1975 and 1995. The status of these children was retrospectively reviewed to determine the differences in outcome between patients prophylactically operated on before the onset of symptoms and those operated on after the onset of symptoms. Fifty-five patients presented with a lipoma of the filum terminale and 158 with a lipoma of the conus medullaris. In the filum terminale group, 28 were asymptomatic at the initial operation, and 27 presented with symptoms. Of the asymptomatic children with filum terminale lipomas, none worsened after surgery, and all remained asymptomatic throughout follow-up (mean follow-up: 3.4 years). Benefits were also observed for the symptomatic patients in this group as no cases of further deterioration were noted, and 5 patients returned to normal clinical status. In the conus group, 71 patients were asymptomatic at initial surgery, and 87 presented with symptoms. In the case of conus medullaris lipomas, 9 of the 71 children who were operated on prophylactically, later deteriorated (mean follow-up: 6.2 years) and required a second untethering operation which resolved all symptoms in 4 cases. Thus, 5 of 71 deteriorated, while 66 remained normal (93%) throughout the period of follow-up. On the other hand, of the 87 patients operated on after the onset of symptoms, 36 (41%) deteriorated further and required subsequent reoperations. In these 87 children, the final outcome at the end of follow-up (mean follow-up: 6.6 years) showed that 20 (23%) patients had deteriorated compared to initial presentation and 44 (51%) remained at initial clinical baseline, while 23 (26%) improved or returned to normal clinical status. Prophylactic surgery in the case of the asymptomatic infant with a spinal lipoma showed a clear benefit. Good outcome was also observed when surgery was carried out after the onset of symptoms. Prophylactic surgery also had a better general outcome by actuarial calculations when only patients with a follow-up of more than 5 years were considered. Deterioration occurred in 5 (16.7%) of the 30 children with a follow-up of more than 5 years, while 25 (83.3%) remained normal. Furthermore, in cases which had prophylactic surgery, there was not only a smaller incidence of deterioration requiring a reoperation, but this group of patients also experienced a longer time interval between initial surgery and the need for reoperation compared to the patients operated on after the onset of symptoms. The authors conclude that spinal lipomas should be operated on as soon as possible on a prophylactic basis, and careful and constant follow-up should be carried out to permit prompt reintervention in cases with deterioration.
The hallmarks of tethered cord syndrome are a low-lying conus medullaris and a thick filum terminale. In diagnosing the tethered cord syndrome, the thick filum terminale is often defined as that greater than 2 mm in diameter. The cutoff of 2 mm in diameter was derived from myelographic measurements a few decades ago, and the true normal diameter of the filum terminale diameter in children or adults remains unknown. We measured the diameters of the filum terminale in vivo in the operating room on 31 children (age range = 2-14 years; mean age = 5 years) undergoing selective dorsal rhizotomy for spastic cerebral palsy. None of them had clinical evidence of tethered cord syndrome. The conus medullaris and filum terminale were videotaped intraoperatively and images were transferred to an image analyzer; the filum diameters at 10 and 15 mm caudal to the conus medullaris were then measured extraoperatively using the computer graphics system. The diameter of the filum at 10 and 15 mm caudal to the conus was 1,211 +/- 209 and 1,163 +/- 245 microm (mean +/- SD), respectively. In all children except one, the conus medullaris ended above the L2 level. The data indicate that filum terminales greater than 2 mm in diameter in children are abnormally thick.
We evaluated bladder function in adults with the tethered cord syndrome using multichannel urodynamics.
A total of 21 patients a mean 39.6 years old (range 20 to 62) with a tethered cord were evaluated. Of the patients 13 were diagnosed with a tethered cord as an adult and 8 had undergone previous spinal surgery. The tethered cord syndrome was diagnosed by magnetic resonance imaging in 20 patients and computerized tomography myelogram in 1. All patients underwent complete neurological and urological evaluation, including multichannel urodynamics. Needle electromyography and video urodynamics were performed in select cases. Microsurgical release of the tethered cord was performed in 19 patients and 2 refused surgery. Urodynamics were done before surgery in 16 of 19 patients and a median of 12.5 months (range 1 to 40) after surgery in 14. In addition, intraoperative urodynamic monitoring and nerve root stimulation were done in 14 patients to prevent nerve root injury at surgery.
At presentation urgency (67%) and urge incontinence (50%) were the most common findings in 18 patients with urinary symptoms. Pretreatment urodynamics in 18 of 21 patients revealed hyperreflexia in 13 (72%), external detrusor-sphincter dyssynergia in 4 (22%), decreased sensation in 4 (22%), decreased compliance in 3 (17%) and hypocontractile detrusor in 2 (11%). Postoperative urodynamic findings were improved in 4 patients (29%) and unchanged in 10 (71%). Preoperative external detrusor-sphincter dyssynergia in 4 patients resolved postoperatively in 3 and was unchanged in 1. Urinary symptoms were improved in 19% of patients (4), unchanged in 76% (16) and worse in 5% (1). To date 7 patients require anticholinergics, 4 require clean intermittent catheterization and 1 is taking an alpha-blocker.
Adults with the tethered cord syndrome are less likely to have urodynamic or symptom improvement after cord release and most often present with irreversible findings which rarely become worse after surgery. These patients need to have careful and continuous followup, including urodynamic studies, due to possible re-tethering with time.
To evaluate the intradural anatomic features of the filum terminale (FT) in fresh human cadavers, analyzing morphological parameters relevant for the diagnosis of the tethered cord syndrome.
Forty-one fresh cadavers were dissected, and the following parameters were evaluated: cadaver height, weight, and age, FT length, FT diameters at the initial point and midpoint, and topographic relationships of the initial and fusion points of the FT to the adjacent vertebrae.
The mean FT length was 156.44 mm (range, 112.8-211.1 mm), the mean initial diameter was 1.38 mm (range, 0.4-2.5 mm), and the mean midpoint diameter was 0.76 mm (range, 0.1-1.55 mm). Four specimens (9.76%) exhibited FT thicknesses of more than 2 mm at their initial points. The FT most frequently started at the middle L1 level (19.51%) and fused with the dura mater at the upper S2 level (31.71%). Two fila (4.88%) started below the L2 level. Statistically significant correlations were observed (Pearson correlation, P < 0.05) between specimen weight and height (P = 0.019), initial point and midpoint diameters of the FT (P < 0.001), initial vertebral level and specimen height (P = 0.012), and initial and fusion vertebral levels (P = 0.004).
Variation ranges were large for almost all anatomic parameters of the FT. Six cadavers (14.63%) in our study fulfilled one of the anatomic diagnostic criteria for tethered cord syndrome. Neurosurgeons must remember the normal variations in the anatomic features of this region when establishing the diagnosis of tethered cord syndrome or performing surgical procedures involving the caudal part of the dural sac.
To determine whether there are magnetic resonance imaging (MRI) characteristics of fatty fila that are correlated with neurological deficits, especially in the presence of a normal-level conus medullaris.
Lumbosacral MRI scans were reviewed for patients with fatty fila who were treated at Duke University Medical Center during a 5-year period. The patients were divided into three groups. Group I patients (n = 5) had fatty fila that were incidentally detected during evaluations for metastases or infections. Group II patients (n = 16) exhibited isolated low back pain but were in neurologically intact condition. Group III patients (n = 15) exhibited neurological impairments consistent with distal spinal cord dysfunction. Several characteristics were measured on the MRI scans, including the location of the conus medullaris, the filum thickness, and the distance of fat from the conus. These results were assessed for statistically significant correlation with the presence of clinical symptoms.
The majority of patients in all three groups demonstrated the normal conus position (L2 or above) and thickened fila. The distance of fat from the conus was the only parameter that demonstrated a statistically significant difference among the groups.
The following findings were noted: 1) patients were likely to exhibit neurological deficits at a younger age (<22 yr in Group III versus 47 yr in Groups I and II); 2) a conus level below L2 was associated with neurological deficits (Group III); 3) filum thickness was not correlated with clinical presentation; 4) fat in the filum within 13 mm of the conus medullaris was most predictive of neurological deficits (Group III).
Spinal and spinal cord malformations are collectively named spinal dysraphisms. They arise from defects occurring in the early embryological stages of gastrulation (weeks 2-3), primary neurulation (weeks 3-4), and secondary neurulation (weeks 5-6). Spinal dysraphisms are categorized into open spinal dysraphisms (OSDs), in which there is exposure of abnormal nervous tissues through a skin defect, and closed spinal dysraphisms (CSD), in which there is a continuous skin coverage to the underlying malformation. Open spinal dysraphisms basically include myelomeningocele and other rare abnormalities such as myelocele and hemimyelo(meningo)cele. Closed spinal dysraphisms are further categorized based on the association with low-back subcutaneous masses. Closed spinal dysraphisms with mass are represented by lipomyelocele, lipomyelomeningocele, meningocele, and myelocystocele. Closed spinal dysraphisms without mass comprise simple dysraphic states (tight filum terminale, filar and intradural lipomas, persistent terminal ventricle, and dermal sinuses) and complex dysraphic states. The latter category further comprises defects of midline notochordal integration (basically represented by diastematomyelia) and defects of segmental notochordal formation (represented by caudal agenesis and spinal segmental dysgenesis). Magnetic resonance imaging (MRI) is the preferred modality for imaging these complex abnormalities. The use of the aforementioned classification scheme is greatly helpful to make the diagnosis.
Tethered cord syndrome, usually discovered in childhood, is a developmental abnormality impairing the longitudinal movement of the spinal cord that can be combined with various forms of spinal dysraphism. Adult onset tethered cord syndrome (ATCS) seems not as rare as once thought, however, low susceptibility in adulthood commonly leads to a delay in diagnosis and therapy. We conducted a meticulous literature research to evaluate the clinical presentation, associated malformations, prognostic factors, as well as the benefits and risks of surgical treatment in ATCS patients. The age of patients at onset of symptoms ranged from 18 to 76 years with a mean of 36.5 years, including 184 males and 202 females. In contrast to the pediatric clientele, pain is the predominant symptom in adults, and elicitating mechanisms like trauma, excessive physical training, or degenerative spinal canal stenosis are reported more often. Surgical untethering aims the restoration of craniocaudal mobility of the spinal cord in order to prevent the further progression of symptoms, to restore neurological function, and to improve pain. In our evaluation of literature, pain was the most responsive symptom after surgical untethering (307 of 368 patients). Sensory and motor symptoms also seem to benefit from the surgery, especially if less than 6 months standing and mild. Improvement could be achieved in 43% (144 of 335 patients) for sensory deficits and 58.6% (191 of 326 patients) for motor deficits. Sphincter troubles are less responsive; they show an improvement in 45.6% (141 of 309 patients). Factors reported to be associated with the postoperative deterioration and/or bad outcome are the split cord malformation, lipomyelomeningocele, previous surgery, rapid motor function worsening experienced shortly before the operation, and long delay in diagnosis. The rate of secondary decline and retethering could not be established in our literature research. We report on an additional case of ATCS with the late onset of symptoms at the age of 49; she underwent surgical untethering with neuronavigational guidance. Performing neuronavigational guidance on the basis of multimodal images (computed tomography and magnetic resonance imaging fused with the intraoperative biplanar X-ray) in our patient showed substantial benefit in the surgical orientation within a complex skeletal and neuronal anomaly.
Surgery of the pediatric spine
- D H Kim
- R R Betz
- S L Huhn
- P Newton
Tight filum syndrome
- L B Poe