Occult lumbosacral dysraphism in children and young adults: diagnostic performance of fast screening and conventional MR imaging

Results of the prophylactic surgery of lumbosacral lipomas 20 years of experience in the Paediatric Neurosurgery Department La Timone Enfants Hospital, Marseille, France

We conducted a retrospective study of children with lumbosacral lipomas treated in the Department of Pediatric Neurosurgery hospital Timone Enfants in the last 20 years. We selected patients with lipomas of the conus medullaris who underwent preventive surgery. 86 ,4 % of the patients remained asymptomatic during the follow-up. Worse results were observed in children older than one year old at surgery with transitional lipoma, with the conus medullaris was below L5 and when the resection had been partial. In view of the results, the authors recommend the preventive surgery before the first year of life under neurophysiologic monitoring in order to perform a total near-total resection with a neural plate reconstitution.

Spinal cord malformations

Malformations of the spinal cord are one of the most frequent malformations. They should be clearly divided into two completely different families of malformations: open dysraphisms and occult dysraphisms. Open dysraphism mostly consists in myelomeningocele (MMC). Its incidence is 1/1000 live births with a wide variation. Folic acid supplementation has been shown to reduce its risk. In most cases, the diagnosis is done prenatally by serum screening and ultrasound and may lead to termination of pregnancy. In case of decision to continue pregnancy, surgical treatment must be achieved during the first days of life, and in 50 to 90% of cases, a ventricular shunt must be installed. The follow-up of these children must be continued throughout life looking for late complications (Chiari II and syringomyelia, vertebral problems, neuropathic bladder, tethered cord). Occult dysraphisms are a heterogeneous group of malformations. Lipomas (filum and conus) are the most frequent and their treatment remains controversial. Diastematomyelia, neurenteric cysts, dermal sinus, and more complex forms (Currarino syndrome) belong to this group. Most of them can and must be diagnosed prenatally or at birth by careful examination of the lower back for the cutaneous stigmata of the disease to decrease the risk of neurological, urological, or orthopedic permanent handicap.

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.

Prevalence of primary tethered cord syndrome associated with occult spinal dysraphism in primary school children in Turkey

The prevalence and associated factors of primary tethered cord syndrome (PTCS) in primary school children were investigated. A cross-sectional study was performed in four demographically different primary schools in Turkey. Demographic, familial and physical data were collected from 5,499 children based on enuresis as a predominant symptom and dermatologic and orthopedic signs as clues of occult spinal dysraphism. Statistical analysis and input of the data were carried out with the SPSS package program 10.00, and logistic regression analysis was used to identify discriminating factors between enuretic children with or without neurologic signs. Of 5,499 analyzed children, 422 (7.7%) had enuresis nocturna, and 19.9% of 422 children had also daytime incontinence. Sixteen of these 422 enuretic children (3.8%) had several dermatologic signs. Five of them had spina bifida on plain radiographies, and 4 of them had cord tethering on lumbar MRI. Fifteen of 422 enuretic children (3.7%) had gait disturbances and orthopedic anomalies without cutaneous manifestations. Six of 15 children had spina bifida on plain graphies and 2 of them had tethered cord syndrome on MRI. The general prevalence of PTCS was found to be 0.1% of 5,499 analyzed children and 1.4% of enuretic children. A good outcome after untethering was found in 83.0% in this series. Practitioners should be aware of these clues of occult spinal dysraphism and resort to further radiologic and neurosurgical assessment. Early surgical intervention may halt the progression of the neurologic deficits and stabilize or reverse symptoms.

[Type II split cord malformation of late clinical onset]

A 68-year-old patient suffered for 8 years from radicular S1 pain on the left side, which was aggravated by walking. After an increased effort, he experienced a violent dorsal pain and sensitive troubles in the left T1 and T2 territories. Low back pain and painful paresthesiae of right leg came on next. Physical examination revealed proprioceptive symptoms on the left, a left pyramidal syndrome and a sacral pilonidal sinus. MRI showed on level of L2 vertebra, a spinal cord duplication in a unique dural tube, corresponding to diplomyelia or split cord malformation (SCM) type II. The patient had low conus medullaris anchored on L3-L4 level. A syringomyelia surmounted this medullar dysraphia. Split cord malformations, SCM type I (diplomyelia) or SCM type II (diastematomyelia), are usually revealed in infancy or early childhood. They are very rarely discovered late in the life. With progress in noninvasive spinal cord imaging, such diagnoses will undoubtedly be made more often in adults.

Prenatal diagnosis of diastematomyelia

INTRODUCTION

Diastematomyelia, also termed split cord malformation, is a form of occult spinal dysraphism characterized by a cleft in the spinal cord. Prenatal diagnosis of this anomaly is possible by ultrasonography (US), and fetal MRI can be used to diagnose the type of diastematomyelia precisely. Diastematomyelia can be isolated or associated with other dysraphisms, segmental anomalies of the vertebral bodies, or visceral malformations (horseshoe or ectopic kidney, utero-ovarian malformation, and anorectal malformation). We present three cases of fetal diastematomyelia investigated using a multimodal prenatal work-up (US, MRI, 3D-CT).

CASES

The first case, detected at 20 weeks' gestation, had a lumbar meningocele. At 30 weeks' gestation, direct US visualization revealed the division of the spinal cord into two hemicords. This patient illustrates an isolated type II diastematomyelia with a favorable prognosis. The second case, detected at 22 weeks' gestation, presented with disorganization of bony process of the vertebral column with a midline echogenic bony spur, asymmetrical hemicords, and a foot malposition. Fetal MRI at 26 weeks' gestation and CT/3D reconstructed at 32 weeks' gestation confirmed a type I diastematomyelia with orthopedic malposition. The third case, detected at 22 weeks' gestation, presented with widening of the lumbar canal and scoliosis. Prenatal work-up (US, MRI) disclosed other visceral malformations (pelvic kidney), which led to the assumption of a complex polymalformative syndrome. The pregnancy was terminated. Fetopathologic examination disclosed even more visceral malformations (anal atresia and unicorn uterus).

Occult spinal dysraphism: evidence-based diagnosis and treatment

This article reviews the scientific evidence behind the diagnostic tools available for the appropriate workup and management of patients with occult spinal dysraphism (OSD). The diagnostic tools include the use of detailed history and physical examination, plain films, ultrasound, MR imaging, and neurophysiologic tests. In addition, the article discusses the epidemiology of the most common causes of OSD in children, which will allow physicians caring for children to develop a pretest probability of disease and make a more educated decision as to when additional diagnostic testing is required.

Newborns with suspected occult spinal dysraphism: a cost-effectiveness analysis of diagnostic strategies

OBJECTIVE

To assess the clinical and economic consequences of different diagnostic strategies in newborns with suspected occult spinal dysraphism.

METHODS

A decision-analytic model was constructed to project the cost and health outcomes of magnetic resonance imaging (MRI), ultrasound (US), plain radiographs, and no imaging in newborns with suspected occult spinal dysraphism. Morbidity and mortality rates of early versus late diagnosis of dysraphism and the sensitivity and specificity of MRI, US, and plain radiographs were obtained from the literature. Cost estimates were obtained from a hospital cost accounting database and from the Medicaid fee schedule.

RESULTS

We found that the choice of imaging strategy depends on the underlying risk of occult spinal dysraphism. In low-risk children with intergluteal dimple or newborns of diabetic mothers (pretest probability: 0.3%-0.34%), US was the most effective strategy with an incremental cost-effectiveness ratio of $55 100 per quality-adjusted life year gained. For children with lumbosacral dimples, who have a higher pretest probability of 3.8%, US was less costly and more effective than the other 3 strategies considered. In intermediate-risk newborns with low anorectal malformation (pretest probability: 27%), US was more effective and less costly than radiographs and no imaging. However, MRI was more effective than US at an incremental cost-effectiveness of $1000 per quality-adjusted life year gained. In the high-risk group that included high anorectal malformation, cloacal malformation, and exstrophy (pretest probability: 44%-46%), MRI was actually cost-saving when compared with the other diagnostic strategies. For the intermediate-risk group, we found our analysis to be sensitive to the costs and diagnostic performances (sensitivity and specificity) of MRI and US. Lower MRI cost or greater MRI diagnostic performance improved the cost-effectiveness of the MRI strategy, whereas lower US cost or greater US diagnostic performance worsened the cost-effectiveness of the MRI strategy. Therefore, individual or institutional expertise with a specific diagnostic modality (MRI versus US) may influence the optimal diagnostic strategy.

CONCLUSIONS

In newborns with suspected occult dysraphism, appropriate selection of patients and diagnostic strategy may increase quality-adjusted life expectancy and decrease cost of medical work-up.

Femoral head osteonecrosis: detection and grading by using a rapid MR imaging protocol

PURPOSE

To design and evaluate a limited magnetic resonance (MR) imaging examination that can be performed rapidly and potentially inexpensively in patients with clinical suspicion of osteonecrosis.

MATERIALS AND METHODS

Both a limited and a full hip MR examination were performed prospectively in 179 hips in 92 patients with clinical suspicion of femoral head osteonecrosis. The presence of osteonecrosis was determined by two radiologists. The percentage of involvement of the femoral head weight-bearing surface was evaluated subsequently for osteonecrosis-positive hips on both sets of images.

RESULTS

Both examinations were performed successfully in all cases. Agreement between the limited and full examinations for presence of osteonecrosis was 98.9% (177 of 179 cases; kappa, 0.97). Forty-six (92%) of 50 patients with femoral head osteonecrosis at both examinations were placed in the appropriate quartile of percentage of femoral head weight-bearing surface involvement by both readers (weighted kappa, 0.94). Incidental findings were made at the full examination that could not be made or were difficult to make at the limited examination.

CONCLUSION

There was excellent agreement between the full and screening MR examinations for both detection of and determining the extent of osteonecrosis. The time and potential cost reduction achieved with a limited examination may allow introduction of MR imaging earlier in the diagnosis of femoral head osteonecrosis, as well as its more widespread use in patient care.