Myelodysplasia in Children

Myelodysplasia in ChildrenMyelodysplasia in children is a deformity resulting from failure of closure of the neural tube late in the first month following conception.

Etiology

Factors include genetic, geographic, and drugs (valproic acid and carbamazepine). The prevalence is reduced by periconceptional folic acid supplementation. The severity of paralysis is reduced by cesarean delivery before rupture of amniotic membranes and onset of labor.

Pathology

The spectrum of defects is broad, with localized or extensive neurological defects.

Brain defects include hydrocephalus, and the varied Chiari malformations that may include herniation of the cerebellum into the upper cervical canal. Mental retardation is common in higher-level lesions.

Cord defect Lesions may be incomplete or complete, open or closed, and occur at different levels. An autonomous functioning cord below the primary lesion may result in segmental spasticity. Diastatomyelia, tethered cords, lipoma, and syringomyelia may be coexisting problems.

Multiple system involvement is common. Major problems include incontinence, urinary infections, and nutritional problems.

Bone and joint deformity are common associated problems. These include clubfeet, vertical talus, knee flexion or extension deformities, hip dislocations, and spinal kyphosis or scoliosis.

Secondary skeletal defects often develop with time and muscle imbalance. These include hip dislocations, progressive scoliosis, and lower limb deformities.

Clinical Features

Prenatal diagnosis is by alpha-fetoprotein determination and ultrasound examination.

Initial assessment is best provided in a multidisciplinary facility with neurodevelopmental, neurosurgical, urologic, and orthopedic consultants available. Make certain management is whole-child oriented. Determine neurological level by neurological examination and muscle testing. Unilateral or incomplete lesions improve prognosis. Often the orthopedic concerns are the least of the child’s problems.

Periodic evaluations are necessary throughout childhood. During each visit, assess overall function, the spine and pelvis for symmetry, the skin for ulcers, and address specific problems identified by the parents.

Hip Deformity

Hip deformity is related to the neurological level. In the past, hip deformity was often overtreated.

Flexion contractures increase with time and may require release.

Hip dislocations are most common in upper lumbar paralysis with muscle imbalance. Hip dislocation itself does not affect the ability to walk. Operative indications include painful dysplasia in the ambulatory patient and fixed pelvic obliquity, which makes sitting difficult or skin care unmanageable. Operative complications, including recurrent deformity, stiffness, pathological fractures, and skin ulcers, are common.

Spinal Deformity

Spinal deformity is common in the more severely affected child. Progression is most likely when associated with cord tethering or hip contractures.

Kyphosis is usually congenital and may be severe. Resection is indicated if the deformity prevents skin closure during neonatal repair of the defect or later if skin breakdown occurs over the apex of the deformity.

Scoliosis may cause suprapelvic obliquity, increasing the risk of decubitus ulcer formation, sitting problems, and impaired hand function. Correct severe or progressive deformity and level the pelvis to distribute skin loading evenly under the pelvis. Manage with a focus on disability rather than deformity. Be aware that poor soft tissue coverage, contractures, impaired sensation, fragile bone, and deficient posterior elements complicate treatment. Pseudoarthrosis rates are decreased with combined anterior–posterior fusions and rigid segmental instrumentation.

Tethered cord Identification and repair are often a focus of management. Be aware that recurrence following repairs is common and that tether is not a cause of increasing deformity.

Knee Deformity

Knee deformities may be congenital.

Flexion deformity may make walking difficult or impossible. Correct significant disability with soft tissue releases, which often require a posterior capsulotomy. Extension osteotomy may be necessary in the older child or adolescent.

Extension deformity may complicate sitting. Release persisting congenital contractures by early percutanous release.

Foot Deformities

Foot deformities are common for both upper- and lower-level lesions. They occur in nearly 90% of upper-level paralysis and 60–70% of those with lower lesions. Spastic segments are common in high-level lesions and cause progressive deformity.

Operative procedures on the foot are often necessary, effective, and successful. Foot ulcers are common problems if the foot is non-plantigrade and stiff. Attempt to preserve motion and create a plantigrade position for standing or for positioning the footrests of a wheelchair. Avoid arthrodesing procedures whenever possible.

Calcaneus deformity results from relative overpull of the anterior tibialis. Manage with an orthotic, anterior tibialis and ankle release, tenodesis of the tendo-Achilles, or transfer of the anterior tibialis to the Achillis tendon.

Clubfeet are common and require operative correction at about a year of age. Correct by extensive posteromedial release or talectomy. Recurrent deformity may require a decancellation procedure. Avoid arthrodesing procedures. Residual varus may be a problem.

Ankle valgus is secondary to a triangular distal tibial epiphysis. Manage by placing a medial malleolar screw that restricts medial physeal growth to correct the valgus. Remove the screw when the ankle is neutral. A valgus deformity at the end of growth may require a distal tibial osteotomy for correction.

Planovalgus foot is best managed by calcaneal lengthening, which provides correction and maintains foot mobility.

Vertical talus deformities require operative correction during the first year. Correct with a single-stage procedure.

Cavus deformity often causes skin breakdown and significant disability. Manage in two stages. First, perform a plantar medial release. Follow with osteotomies and tendon transfers to maintain correction.

Toe deformities include dorsal bunion, clawing, or simple flexion deformities. Manage by releases and osteotomies to preserve function. Avoid fusions when possible.

External rotation deformity is nearly always secondary to external tibial torsion. Correct by a supramalleolar medial rotational osteotomy and fix with a short plate and screws.

Walking

Walking ability is related to level of paralysis, knee flexion deformity, mental status, family compliance, and gait training. It is not related to hip reduction status. Most sacral and lumbar, and a few thoracic level patients walk. Walking often deteriorates in late childhood and adolescence, when the body weight increases more than muscle mass. Provide walkers for gait training and crutches for long-term use. Walking must be energy efficient, convenient, and comfortable to be maintained. Combinations of independent walking and wheelchair dependence often provide a good long-term solution for mobility.

Problems

Pathologic fractures may follow minimal trauma, manipulative treatments, or operative procedures. Pathologic fractures may be confused with osteomyelitis. Avoid casts, and splint until comfortable. Avoid long-term immobilization. Permanent intramedullary fixation may be useful in allowing early mobility and preventing refracture. Physeal stress fractures may occur in the distal femur and upper tibia.

Cord tethering is suggested by loss of function, increasing deformity, or pain. Untethering often does not arrest deformity progression or eliminate the need for additional orthopedic procedures.

Skin breakdown includes sacral decubitus and foot ulcers. These are common serious problems that cause considerable disability. Reduce risk by correcting rigid foot deformities and severe pelvic obliquity.

Latex allergy occurs in about 5% of patients. Screen patients for a history of latex allergy. Create a latex-free environment in both the hospital and at home. Before any operative procedure, make certain the problem is assessed by an anesthesiologist and considered for preoperative prophylaxis.

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