by Carol Hart, Ph.D.
AAP News Correspondent
From AAP News, vol. 13, no. 9, September 1997
Chris McAfee's baby girl was born with unusual marks along the midline of the lower back, a lipoma with a dimple and a hemangioma.
Three hospital physicians reassured the McAfees that these marks were nothing to be concerned about, and a spinal ultrasound was reported as negative. Their pediatrician, however, was still worried, and the baby was ultimately referred for an MRI at the nearest children's hospital, in Philadelphia.
When the McAfees returned for the result, they learned a nine-syllable word new to them and probably to the first three physicians who had examined their baby: Hannah had lipomyelomeningocele.
Beth Reeth's daughter Jennafer was born with a small patch of hair over the lower spine and a dimple directly below it. The pediatrician in their small Michigan town assured her that the hair would eventually fall out and the dimple was harmless.
Later on, when she and her husband were dissatisfied with care for the toddler's constipation and urinary tract infections, they sought another opinion. Almost by chance, they showed the hairy patch to the second doctor, who recognized its significance.
The MRI showed syringomyelia and possible spinal cord tethering. Their neurosurgeon finds no abnormal neurologic signs and is reluctant to operate. The Reeths are currently seeking opinions from pediatric neurosurgeons more experienced with this and other forms of occult spinal dysraphism.
Occult spinal dysraphism (OSD) is a general term for congenital spinal cord abnormalities that cause progressive neurologic dysfunction.
The causes of the neurological deficits include tethering or fixation of the spinal cord, as from a thickened, inelastic filum terminale, as well as tumors that grow into and compress the cord, such as a fatty tumor or lipomyelomeningocele.
Without early surgery, these children will suffer neurologic changes that might be irreversible. Such children are at high risk for recurrent meningitis (if a dermal sinus tract is present), bladder and bowel incontinence, foot and leg deformities, and disabling motor deficits.
"They call these occult spinal dysraphisms, but in fact they are not really occult," said David McLone, M.D., FAAP, professor of surgery at Northwestern University and chairman of pediatric neurosurgery at Children's Memorial Hospital, Chicago.
"Most of these children have markers--either a hemangioma, a hairy patch, a dimple, or a lump--that tells you there's some problem with the underlying nervous system."
Children with anorectal or genitourinary anomalies are another group with a high incidence of associated OSD.
In most cases, the markers of OSD are not subtle, and neither parents nor physicians will fail to notice them. However, these babies rarely show neurologic impairment, so a physician who is unaware of OSD will have no reason to suspect underlying abnormalities. The symptoms of tethered cord syndrome are unlikely to appear for months or years, and onset can be insidious.
"How do you tell if a 6-month-old is incontinent? The answer is it's really hard," said W. Jerry Oakes, M.D., FAAP, professor and chief, section of pediatric surgery, University of Alabama and Children's Hospital of Alabama. These children may go undetected until 3 years of age or later.
"The element of denial is strong in all of us," Dr. Oakes remarked, and described the court case of a pediatrician who did not recognize the significance of cutaneous markers and later took a "wait-and-see" approach to the child's incontinence. The diagnosis was made after the parents sought a second opinion at age 4½, but the child's incontinence did not resolve after the tethered cord was surgically released. The pediatrician was found liable for the child's considerable and ongoing medical problems, because the delay in diagnosis left the child incontinent for life.
"This is a time when we know the natural history of OSD, and if you trained 20 years ago and don't keep up, you're in trouble," Dr. Oakes commented.
A spinal ultrasound is often sufficient for confirming the OSD diagnosis. However, it takes a good pediatric ultrasonographer to make that diagnosis, experts cautioned. Dr. Michael Scott, professor of surgery at Harvard University and director of clinical pediatric neurosurgery at Children's Hospital, Boston, said that the ultrasound is also less reliable in a baby older than 2 months.
Some lesions, such as a dermal sinus tract going into the lower end of the spinal cord, may be missed even by an experienced radiologist, Dr. Scott said.
In addition, certain skin markers have such a high association with spinal cord abnormalities that they would be indications to investigate the child more fully with an MRI. These would include, he said, a midline or slightly eccentric mass or a hairy patch in the lumbar region.
During the last two decades, understanding of the natural history of OSD has improved, as have surgical approaches to treatment, Dr. Oakes said.
"There's a risk that verges on 100% for a lipomyelomeningocele and a fairly low risk of injury from operative intervention, along with a fairly high efficacy rate," Dr. Oakes said. "Add that up, and you have an operation as early in life as you can get them on the table."
There are seven pathologic changes that can be found in OSD (see sidebar), and both the natural history and the technical demands of the surgery vary for those different lesions.
"At the very least there is a tenfold difference in safety in favor of having an operation," provided the surgery is undertaken by an experienced pediatric neurosurgeon Dr. Oakes said.
Children with OSD are being detected and referred at an earlier age than in the past, according to these pediatric neurosurgery experts. Yet some children with obvious cutaneous signs are still seen late, after the onset of problems that may be irreversible.
"We see children come in with E. coli meningitis who are left permanently impaired, often with post-infectious hydrocephalus requiring a shunt," said Dr. McLone. "We see children with lumps on their back who are not referred until they have lost bladder function or developed progressive foot deformity or atrophy of an extremity. Surgery prior to onset in any of these cases would have prevented the problem."
Some children lack cutaneous markers and will not be diagnosed until symptoms appear. The diagnosis may depend on the pediatrician's awareness that OSD can underlie bladder or bowel control problems, Dr. Scott said. Along with urinary incontinence and foot deformities, pain with activity is one of the more common presentations.
"This pattern becomes very obvious." said Merion Walker, M.D., FAAP, professor and head, division of pediatric neurosurgery, University of Utah and Primary Children's Medical Center, Salt Lake City. "They can't walk around the mall any more because it hurts too much, and they have to rest very often."
Dr. Walker and Dr. McLone remarked that the diagnosis can be missed when a child with cutaneous markers is referred to a neurosurgeon lacking pediatric experience who finds no neurologic deficits and pronounces the child normal.
"We see that situation more commonly than a pediatrician who misses it. OSD is a childhood disease and it's best treated by physicians who take care of children," Dr. Walker said.
When managed care companies control access to testing and neurosurgical consults, diagnosis and treatment might be delayed, he added.
"The experienced radiographer tends to be in a children's hospital or a university setting where they have a strong children's service, and those tend to be more expensive."
If the insurer forces the choice of ultrasound for evaluation, he said, and that test is read as normal, then an MRI will not be authorized. Similarly, the managed care system's neurosurgeon may not appreciate the need for early surgery.
"Once the children get to us we can fight that battle and justify the need for tests and treatment. But less experienced physicians might not understand they have reasons to fight. I think it's been a major problem."
These signs might occur anywhere along the midline but are seen most frequently in the lumbar region. Combinations of these cutaneous stigmata are common.
Urologic
Orthopedic
Neurologic