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Radiological Case of the Month
Monica Epelman, MD;
Imad R. Makhoul, MD, DSc;
Dorith Golsher, MD;
Polo Sujov, MD
From the Departments of Radiology (Drs Epelman and Goldsher) and Neonatology
(Drs Makhoul and Sujov), Rambam Medical Center, Rappaport Faculty of Medicine,
Technion-Israel Institute of Technology, Haifa, Israel. Dr Epelman is currently
affiliated with the Department of Diagnostic Imaging, Hospital for Sick Children,
Toronto, Ontario.
Arch Pediatr Adolesc Med. 2002;156:407-408.
A FULL-TERM, 2725-g female infant was born by vacuum extraction delivery
following an uncomplicated pregnancy. The infant appeared normal except for
a tuft of dark hair covering the skin of the lumbar area (Figure 1). She moved her extremities well and showed normal sensation
and strength.
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Figure 1.
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As part of the patient workup, a radiograph of the spine was was obtained
followed by imaging of the spine with ultrasonography in axial (Figure 2) and midsagittal planes (Figure 3) and magnetic resonance imaging of the spine (Figure 4).
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Figure 2.
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Figure 3.
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Figure 4.
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Denouement and Discussion: Occult Spinal Dysraphism (Tethered Cord, Diastematomyelia, and Spinal Lipoma)
Figure 1. Photograph of the
newborn's back shows a copious, localized hair tuft over the lumbar area.
Figure 2. Axial ultrasonographic
scan at the level of L1 demonstrates division of the spinal cord into 2 portions
(arrows).
Figure 3. Midsagittal ultrasonographic
scan shows the spinal cord (arrow) to be tethered posteriorly by a lipoma
(arrowheads).
Figure 4. Magnetic resonance
imaging in the coronal plane (T1-weighted) demonstrating a split spinal cord
(arrows) from diastematomyelia and a small lipoma (arrowhead).
The term dysraphism means incomplete fusion
of a raphe. The skin and the nervous system share a common ectodermal origin.
Differentation of the neural ectoderm from the epithelial ectoderm occurs
during the third to the fifth week of gestation. Cleavage occurs concurrently
with formation and closure of the neural tube.1
The embryologic concurrence of events explains simultaneous occurrence of
"occult" dysraphic lesions and minor malformations of the skin. Awareness
of the cutaneous manifestations of underlying spinal cord malformations is
critical because dysraphic malformations can cause damage from tethering of
the spinal cord.
While during early fetal life the spinal cord occupies the entire length
of the vertebral column, differential growth results in progressive ascent
of the conus medullaris. In the newborn, the conus medullaris can be at the
level of L2/L3 but by the age of 3 months is at the level of L1/L2, as in
adults. Tethering of the cord prevents the progressive ascension of the conus
with continued somatic growth and anchors the conus at or below the L2 level.
Flexion of the normal spine is associated with upward movement of the cord
and if the cord is fixed or tethered, traction injuries occur and there is
damage to the lower cord and conus.2
Split cord malformations are anomalies in which the spinal cord is cleft
over a portion of its length by either a fibrocartilaginous or a bony septum
originating from the posterior part of the vertebral body. The terms diastematomyelia and diplomyelia
have created confusion; hence, they have been superseded by the term spilt cord malformation. The malformation results from
disarry of midline axial integration during gastrulation, producing a split
neural tube.3 In both types of malformation
there is a tethering element that results in neurologic deterioration.4
The neurologic symptoms result from flexion and extension movements
of the cord that produce traction and trauma from the impaling septum. The
clinical presentations of occult spinal lesions vary. Clinical signs could
appear at birth or be delayed until adulthood. Tethering from any cause may
produce back, leg, or groin pain, progressive lower extremity sensorimotor
dysfunction, urinary dysfunction from neurogenic bladder, bowel incontinence
or constipation, lower extremity orthopedic deformities, and progressive scoliosis.5
Dysraphism should be diagnosed and surgically repaired before symptoms
and signs of irreversible neurologic impairment are evident. Cutaneous abnormalities,
such as hypertrichosis, a dimple, or a lipoma, might be the only clues to
an underlying tethered cord. This is particularly seen in newborn infants
with spinal dysraphism; 71% to 100% of patients have these signs.6-7 A high index of suspicion should
occur when any of the above-mentioned cutaneous abnormalities is present so
that spinal dysraphism can be recognized and managed to prevent irreversible
neurologic impairment.
AUTHOR INFORMATION
Accepted for publication October 23, 2000.
Corresponding author: Monica Epelman, MD, Department of Diagnostic
Imaging, Hospital for Sick Children, 555 University Ave, Toronto, Ontario,
M5G 1X8, Canada.
REFERENCES
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1. Drolet B. Birthmarks to worry about: cutaneous markers of dysraphism. Dermatologic Clinics. 1998;16:447-453.
FULL TEXT
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2. Harlow CL, Partington MD, Thieme GA. Lumbosacral agenesis: clinical characteristics, imaging and embryogenesis. Pediatr Neurosurg. 1995;23:140-147.
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3. Dias MS, Walker ML. The embryogenesis of complex dysraphic malformations: a disorder of
gastrulation? Pediatr Neurosurg. 1992;18:229-253.
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4. Dias MS, Veetai Li. Pediatric surgery for the primary care pediatrician, part II: pediatric
neurosurgical disease. Pediatrics Clin North Am. 1998;45:1539-1578.
5. Dias MS, McLone DG. Spinal dysraphism. In: Weinstein SL, ed. The Pediatric Spine: Principles
and Practice. New York, NY: Raven Press; 1994:343-368.
6. Keim HA, Greene AF. Diastematomyelia and scoliosis. J Bone Joint Surg Am. 1973;55:1325-1434.
FREE FULL TEXT
7. Scatliff J, Kendall B, Kingsley D, et al. Closed spinal dysraphism: analysis of clinical, radiological and surgical
findings in 104 consecutive patients. Am J Radiol. 1989;10:269-277.
SECTION EDITOR: BEVERLY P. WOOD, MD
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