MYELOGRAPHIC ASSESSMENT OF OCCULT FORMS OF SPINAL DYSRAPHISM

High-resolution constructive interference in steady-state imaging in tethered cord syndrome: technical note

BACKGROUND

Differentiation between nerve roots and the tethered filum terminale in magnetic resonance images remains challenging. It is, however, crucial to select patients for surgical intervention.

METHOD

In 1 patient with progressive and 2 patients with stable clinical signs of tethered cord syndrome (TCS), images reconstructed from a 3D constructive interference in steady-state (CISS) sequence were compared with those obtained from a regular T2-weighted fast spin echo sequence.

RESULTS

Nerve roots of the cauda equina were suppressed, whereas visualization of the filum terminale was much improved in high-resolution CISS sequences. In addition, the level of adhesion of the filum could be localized in relation to elements of the spinal cord. The imaging results were confirmed during surgery and the patient improved considerably after the intervention. The advantages of CISS were also apparent in 2 other patients who are still being observed.

CONCLUSION

Constructive interference in steady-state imaging should be considered in the presurgical routine for patients with TCS.

Surgical treatment of late neurological deterioration in children with myelodysplasia

Late deterioration of the neurological condition in patients operated on for myelomeningocele repair has been repeatedly reported in the literature. At the present time magnetic resonance imaging (MRI) allows one to recognize various pathological conditions which can be amenable to surgical correction in these patients, such as Chiari type II malformation, hydro/syringomyelia, decompensated hydrocephalus, and tethered spinal cord. The authors report their experience with 26 myelodysplastic children operated on for myelomeningocele repair in the early neonatal period, who exhibited late deterioration at variable time intervals from the first operation. The children were examined pre-operatively by means of MRI; the results were compared with those provided by MRI in 46 myelodysplastic children who underwent the investigation as a routine follow-up control. The MRI findings were subdivided into 4 main groups of increasing severity from 1 to 4; in some subjects, associated pathological conditions (Chiari II malformation, hydromyelia, etc.) were detected as well. Twenty-two out of the 26 patients with late neurological deterioration were operated on. Eleven of them (grades 2 to 4) underwent detethering of the fixed conus, with an improvement of their clinical picture from mild to good. On the other hand the remaining 11 subjects (grades 1 to 2) improved their condition following the correction of the associated abnormalities (malfunctioning CSF shunt: 5 cases; hydromyelia: 4 cases; symptomatic Chiari II malformation: 2 cases).

The tethered spinal cord syndrome: a correlation of radiological features and peroperative findings in 30 patients

The aim of this investigation is to evaluate the accuracy of the diagnostic parameters of the radiological features, especially in conventional lumbar myelography, since these will be used in the future as a gold standard for new developing diagnostic methods like ultrasonography (US) and magnetic resonance imaging (MRI). A short review of the clinical symptoms and diagnostic radiology of the tethered spinal cord (TSC) is given. The radiological features of the TSC syndrome are compared with the peroperative findings in 30 patients investigated and operated in our hospital. All patients showed lumbar or sacral osseous malformations on the plain X-ray films. This means a high diagnostic sensitivity although the specificity for TSC is low. Conventional myelography had a sensitivity of 0.82 and positive predictive value of 0.94, while the specificity and negative predictive value are respectively 0.96 and 0.85. The positive predictive value of the total diagnostic procedure of plain X-ray films and lumbar myelography for TSC may be estimated at 1.

Diagnosis of tethered cords by magnetic resonance imaging

Thirty children presented with signs and/or symptoms of tethered spinal cord, 13 in association with spina bifida occulta and 17 after myelomeningocele repair. Preoperative magnetic resonance imaging (MRI) of 27 children showed tethering (27), intradural fat (17), distal syrinxes (8), and thickened filum terminale (2). There was an excellent correlation between MRI and the surgical findings. Postoperative MRI was obtained within 1 year after operation in 14 children; spinal cord ascent was seen on only four studies and retethering was suspected on five studies. We consider MRI the procedure of choice to diagnose a tethered cord because this technique accurately defines anatomical relationships without risk to the patient. In addition, we conclude that cord ascent is seen less often than expected and that retethering may occur, especially to cadaveric dura mater.

Computed tomographic myelography in the investigation of childhood scoliosis and spinal dysraphism

The combined investigations of positive contrast myelography and computed tomographic (CT) myelography were performed on 53 consecutive children. Thirty-eight (72%) of these investigations were performed as a routine pre-operative procedure to identify occult spinal dysraphism in patients with childhood scoliosis; the remainder were because of the "orthopaedic syndrome", cervical radiculopathy, back pain and patients with clinical findings to suggest spinal dysraphism. In the 20 patients (38%) with idiopathic scoliosis, there was no case of spinal dysraphism and CT myelography provided no additional information to the myelogram. In the seven patients with spinal dysraphism the plain radiographic abnormalities identified were lumbar vertebral abnormalities (five), thoracic vertebral abnormalities (one), and sacral agenesis (one). Diastematomyelia was found in four patients, a low tethered cord and lipoma in two patients and a large lipoma in one patient. In all of these cases the myelogram indicated the intraspinal abnormalities; however, CT myelography provided more precise anatomical detail. We conclude that CT myelography is not indicated in the initial preoperative assessment of idiopathic scoliosis but should be reserved for patients with congenital or complicated scoliosis where the association with dysraphism is well recognised.

Lumbosacral lipoma causing tethering of the conus: case report

We report a case of tethered cord syndrome treated surgically. As in many reported cases, the treatment was successful on pain but only partially so on sphincter dysfunction. The most important diagnostic investigation is CT scanning with contrast medium.

Magnetic resonance imaging in occult spinal dysraphism

The value of magnetic resonance imaging (MRI), compared to myelography and computerized tomography, is illustrated in six patients with occult spinal dysraphism. MRI proved to be the diagnostic tool of choice.

Magnetic resonance and CT imaging of diastematomyelia

The clinical, MRI and CT features of diastematomyelia with an uncommon clinical course are reported. Possible pathogenetic aspects in the late onset of symptoms are discussed implying vascular factors. MRI provides direct visualization of the split cord and low conus, confirming that frontal images are preferable.

Surgically confirmed myelographic classification of congenital intraspinal lipoma in the lumbosacral region

Twenty-four cases of histologically confirmed congenital intraspinal lipoma of the lumbosacral region were studied by means of myelography with metrizamide. The findings were compared with intraoperative observations. Myelography with metrizamide clearly revealed the detailed intrathecal structures and allowed a classification of intraspinal lipomas into four types, in terms of their insertion into the conus medullaris: dorsal type, either with direct or indirect (via an intrathecal stalk) insertion of the extrathecal lipoma into the dorsal aspect of the conus medullaris; caudal type; combined type; and filar lipoma. Based on our surgical experience in untethering and decompression of the lesions, the classification was found to be useful in designing a safe and effective surgical procedure which minimized all possible trauma to the intrathecal neural structures.

Imperforate anus: the neurologic implication of sacral abnormalities

The association of imperforate anus with bony sacral abnormalities and neurologic deficits is well recognized. These neurologic deficits have been considered static rather than progressive. However, recent experience indicates that some patients may develop progressive neurologic problems due to spinal cord lesions that are amenable to neurosurgical correction. To investigate the frequency of such lesions, routine myelography of imperforate anus patients with sacral anomalies was undertaken. The extraordinarily high incidence of unsuspected lesions known to cause progressive bowel, bladder, and musculoskeletal dysfunction is the basis of this interim report. Thirty percent of patients with anorectal abnormalities had sacral dysplasia. Of the nine patients undergoing myelography to date, eight have been abnormal. Six children had a tethered spinal cord, one had narrowing of the bony spinal canal and dural sac stenosis, and one an anterior meningocele. Spinal cord conditions that may cause deterioration of bowel, bladder, and extremity function should be defined and corrected before irreversible damage occurs. Because of the high incidence of spinal cord lesions detected in these patients with coexisting anorectal and sacral anomalies, routine screening for spinal cord lesions is recommended.

Gas myelography in the investigation of occult spinal dysraphism

In patients presenting with suspected spinal dysraphism of the occult type, particularly children, cisternal gas myelography is coming to be accepted as the radiological investigation of choice. The technique of the examination as performed on 40 such patients is described in detail. There have been no complications. Twenty-five patients showed abnormalities of the cord together with low termination and abnormal fixation of the conus. The visualization was excellent in terms both of reliability and detail. The reasons for the difficulties in demonstrating these lesions using positive contrast and for preferring gas myelography are discussed.

Lumbosacral lipomas: critical survey of 26 cases submitted to laminectomy

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Tethering of the conus medullaris within the sacrum

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DIASTEMATOMYELIA. A CRITICAL SURVEY OF 24 CASES SUBMITTED TO LAMINECTOMY

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