Magnetic resonance imaging: lumbosacral lipoma

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.

Whole spine MRI is not required in investigating uncomplicated paediatric lumbosacral lipoma. A retrospective single-institution review

PURPOSE

Lumbosacral lipoma (LSL) is a severe occult spinal dysraphism, frequently associated with neurological, urological and orthopaedic complications. Whole spine imaging is typically performed to identify concomitant, but spatially separate, congenital anomalies. Our hypothesis: the incidence of additional, clinically significant abnormalities of the neuraxis is low; thus, imaging should be optimised at the lumbosacral region. We aim to assess the prevalence and relevance of LSL-associated lesions.

METHOD

A single-centre, retrospective, radiological review using a prospectively maintained operative database.

INCLUSION CRITERIA

children (< 16 years) with confirmed diagnosis of LSL and received whole spine MRI. Fatty filum, syndromic cases and cutaneous stigmata above lesion level were excluded. Data was extracted from radiological imaging, reports and clinical correspondence.

RESULTS

One hundred twelve patients (40:72, M:F) aged 0.5 years (0.2-2.7) (median ± IQR) with LSL had whole spine MRI between 2001 and 2017. Classification of LSL: transitional 48 (43%); dorsal 30 (27%); caudal 28 (25%) and chaotic 6 (5%). Additional anomalies included syringohydromyelia 44 (39%), subcutaneous tract 19 (17%), abnormal vertebral segmentation 18 (16%), dermoid cyst 1 and 1 Chiari I deformity. There were no Chiari II malformations. No child required surgery for an associated lesion. Binary logistic regression revealed no factors associated with predicting secondary lesions.

CONCLUSIONS

In congenital LSL, additional anomalies of the neuraxis are typically loco-regional rather than pan-CNS and additional lesions are rarely clinically significant. The loco-regional distribution of anomalies suggests that only lumbosacral spinal imaging is required in the initial evaluation of LSL. Such a policy would lessen the anaesthetic/sedation time for children and reduce imaging cost per patient. MRI protocols could be refined to optimise imaging quality at the region of interest.

Critical analysis of the Chiari malformation Type I found in children with lipomyelomeningocele

OBJECT

Occasional comments are found in the literature regarding patients with lipomyelomeningocele and concomitant Chiari malformation Type I (CM-I). The object of this study was to explore the association between these two conditions.

METHODS

The authors performed a retrospective database analysis of lipomyelomeningocele cases to identify cases of concomitant CM-I. Analysis of posterior fossa volume (based on the Cavalieri principle) was performed in all identified cases in which appropriate neuroimages were available, and the results were compared with those obtained in age-matched controls. Seven (13%) of 54 patients with lipomyelomeningocele were found to also have CM-I. Two of these were symptomatic (cervicothoracic syrinx and occipital headaches) and required posterior fossa decompression. No correlation was found between the amount of hindbrain herniation and the level of the conus medullaris or the type of lipomyelome-ningocele (for example, caudal or transitional). Volumetric studies of the posterior fossa revealed normal age-matched volumes in all but one patient (who had asymptomatic CM-I).

CONCLUSIONS

The incidence of CM-I in patients with lipomyelomeningocele appears to be significantly greater than that of the general population and the association rate is too high for the finding to be a chance occurrence. Decreases in the volume of the posterior cranial fossa were not found in the majority of patients in this small cohort; therefore, the cause of the concomitant occurrence of lipomyelomeningocele and CM-I remains undetermined. Clinicians should consider obtaining imaging studies of the entire neuraxis in patients with lipomyelomeningoceles and should investigate other causes for syringes found in association with lipomyelomeningoceles.

Pre- and post-operative hydromyelia in spinal dysraphism

BACKGROUND AND PURPOSE

There has been limited description of hydromyelia after surgery for spinal dysraphism. The opportunity to compare pre- and post-operative hydromyelia in patients with spinal dysraphism has been possible in two groups of patients using MRI. Post-operative assessment and possible relationship of hydromyelia to clinical findings has been made during a 7- to 14-year period.

METHODS

A total of 38 patients with congenital lumbar or sacral lipomas and 20 with diastematomyelia were studied pre-operatively with a 1.5-T MRI. Most patients in each group were examined with surveillance MRI (1.5 T) post-operatively. Clinical correlations were carried out with each examination.

RESULTS

Of the 38 dorsal or terminal lipoma post-operative patients, hydromyelia increased in 3 and was a new finding in 4. One symptomatic patient in the latter group had extensive septated lumbar hydromyelia. In 8 of 20 diastematomyelia patients, pre-operative hydromyelia was unchanged post-operatively. Hemicord hydromyelia developed in 1.

CONCLUSION

Hydromyelia of varying degree was found in almost one-third of post-operative dorsal or terminal lipoma patients and nearly one-half of diastematomyelia patients. In five post-operative lipoma and two diastematomyelia patients, significant neurological findings remained. One of the six post-operative lipomas had new extensive lumbar hydromyelia that may have been responsible for the patient's symptoms. In the remaining symptomatic patients, hydromyelia was absent or modest.

Intramedullary spinal tumors of disordered embryogenesis

Abnormal spinal embryogenesis is quite commonplace. While greater than 90 percent of these errors of embryogenesis leads to occult spinal dysraphism with minimal neurologic or orthopedic sequelae, there is a significant minority of these anomalies which leads to the formation of the so-called 'congenital tumors of disordered embryogenesis'. The purpose of this article is to discuss the embryology, presentation, diagnosis and management of the spinal dysraphic states with particular emphasis on those errors which lead to mass lesions in the spinal canal such as dermoids, epidermoids, lipoma/lipomyelomeningocoele and neurenteric cysts. We also include lesions such as dermal sinus tracts and thickened filum terminale in our discussion with particular emphasis on their relationship to the tethered cord syndrome. Proper surgical management of these various conditions necessitates a thorough understanding of their embryologic etiology and the anatomic/physiologic ramifications that such lesions have on the developing spinal cord.

Treatment and prevention of tethered and retethered spinal cord using a Gore-Tex surgical membrane

The incidence of the tethered cord syndrome after repair of spinal dysraphism is not insignificant. A retethered spinal cord may also develop after an untethering operation. In order to treat and/or prevent the tethered and retethered spinal cord, the authors developed and successfully used a new method in 12 cases. After complete release and reconstruction of the spinal cord, a Gore-Tex surgical membrane was placed over the cord and fixed to the lateral dural surface with stay sutures. During a postoperative follow-up period ranging from 23 months to 7 years, no further neurological deterioration was observed in the 12 patients and magnetic resonance imaging studies showed no adhesion of the spinal cord to the operative site. It is concluded that this simple new method is effective for the treatment and prevention of tethering and/or retethering of the spinal cord, although a longer follow-up study is required.

Myelomeningocele and thick filum terminale with tethered cord appearing as a human tail. Case report

Tail-like caudal appendages may be associated with spinal dysraphism, particularly with spinal lipomas or lipomyelomeningoceles. An unusual case is presented of a patient with a myelomeningocele and a thick filum terminale with tethered spinal cord, which presented with the external appearance of a human tail. A review of the literature reveals that human tails may be associated with dysraphic conditions. Extensive neuroradiological examinations should be performed for all such cases of apparent tails.

Surgical treatment of the retethered spinal cord after repair of lipomyelomeningocele

In a series of 75 patients with surgically treated lipomyelomeningoceles, the neurological condition of six patients deteriorated 6 months to 14 years after the operation due to repeat tethering of the spinal cord. The tethering resulted from postoperative dense adhesion between the cord and the overlying dura mater. Two of the six patients underwent conventional repeat untethering procedures, and the remaining four were successfully treated with a new surgical technique developed by the authors to prevent such dural adhesion. For this procedure, after complete untethering of the spinal cord, the lumbosacral cord is retained in the center of the dural sac by fine stay sutures between the pia mater of the conus medullaris and the ventral dura mater. In addition, the dura mater is tacked to the posterior arch which is reconstructed with bone grafts at one or two bifid vertebral levels. During a postoperative follow-up period of 1 to 3 years, no further deterioration has been observed and magnetic resonance studies have demonstrated a space filled with cerebrospinal fluid (CSF) around the lumbosacral cord. The authors conclude that long-term observation, both neurological and radiological, is essential even after successful repair of a lipomyelomeningocele. This new surgical procedure can maintain a CSF bath around the lumbosacral cord, thus preventing dural adhesion. Application of this technique will hopefully be beneficial in lipomyelomeningocele patients with a high risk of cord retethering after initial repair.

Thickened fatty filum terminale: MR imaging

MR images of four patients with a thickened filum terminale showing a fat signal are presented. There were no related symptoms and no evidence of tethering. The thickened fatty filum terminale seemed to be a developmental anomaly and without clinical significance. As the incidence of this anomaly was 0.24% in our series, knowledge of its possible presence of this anomaly is important for routine reviews of MR image.

Leptomyelolipoma: analysis of 20 cases

Leptomyelolipoma (lumbosacral lipoma) is a common form of spinal dysraphism. The deficits produced include sensory, motor, bowel, and bladder dysfunction, and vary in incidence between the pediatric and adult populations. Twenty patients treated surgically at the Mount Sinai Hospital between 1972 and 1988 are reviewed. Fifty percent were 12 years of age or less and 50% were older than 18 years of age. The surgical approach was designed to accomplish untethering of the conus medullaris, debulking of the lipomatous mass compressing the cord, reconstruction of the dural canal, and reapproximation of the paraspinal muscles and lumbosacral fascia to prevent future trauma. Postoperatively, no patient experienced deterioration of neurological function. Of the symptomatic patients. 67% displayed dramatic improvement or became asymptomatic and 33% experienced stabilization of their deficits. The symptoms most resistant to surgical correction were orthopedic foot deformities and bowel dysfunction, whereas bladder dysfunction, motor weakness, and radiculopathies were most amenable to surgical therapy. Early surgical repair is recommended in these cases to forestall irreversible neurological damage.

MRI study of lumbosacral lipoma in children

The authors report 16 cases of lumbosacral lipoma in children studied by MRI. The exact position of the cord and its relationship to the lipoma were well demonstrated in all cases but one. There was as high incidence (25%) of syringomyelia in the terminal conus. Arnold Chiari malformation was never associated, which differentiates lumbosacral lipomas from myelomeningoceles. However, the nerve roots and their relationship to the lipoma were rarely visualized. Despite these drawbacks, MRI is the examination of choice if lumbosacral lipoma is suspected in children.