At birth, a defect of the vertebrae is noted with protrusion of the meninges and neural elements through an external sac (Lutenhoff, 1997).

The obvious physical manifestation of myelomeningocele is paraplegia caused from spinal cord malformation.

Myelomeningocele patients frequently are described as belonging to certain groups, based on the motor or neurosegmental lesion level. This approach is useful for general functional prognosis and anticipation of specific musculoskeletal complications.

In the thoracic group, innervations of the upper limb and neck musculature and variable function of trunk musculature are present with no voluntary lower limb movements. Patients with thoracic malformations have more involvement of the central nervous system (CNS) and associated cognitive deficits (Liptak, 2004).

In the high-lumbar group, variable hip flexor and hip adductor strength is characteristic, and absence of hip extensors, hip abductors, and all knee and ankle movements are noted (Liptak, 2004).

In the low-lumbar group, hip flexor, adductor, medial hamstring, and quadriceps strength is present; strength of the lateral hamstrings, hip abductors, and ankle dorsiflexors is variable; and strength of the ankle plantar flexors is absent. In the sacral-level group, strength of all hip and knee groups is present, and ankle plantar flexor strength is variable (Liptak, 2004).

“Muscle tone in any of these groups of patients with myelomeningocele usually is weakened; however, up to two thirds exhibit some upper motoneuron signs, with only 9% demonstrating a true spastic para paresis” (Johnson, 2004).

Lack of upper limb coordination is common, especially in patients with hydrocephalus. This lack of coordination also may be related to Arnold Chiari II malformation, motor-learning deficiencies, and/or delayed development of hand dominance. Affected children have problems with fine motor tasks, particularly when timed. New-onset weakness in the upper extremities may be a hallmark of progressive neurological dysfunction (Brown, 2001).

Spinal and lower extremity deformities and joint contractures are prevalent in children with myelomeningocele. Multiple factors may be involved, including intrauterine positioning, other congenital malformations, muscle imbalances, progressive neurological dysfunction, poor postural habits, and reduced or absent joint motion (Brown, 2001).

The musculoskeletal deformities that occur are related to the functional level of the lesion. Thoracic and high-lumbar groups tend to have increased incidence of lumbar curvature, hip abduction and external rotation contractures, flexing of the knee, and contractures of the ankles. (Barker) Unopposed flex of the hips and adduction contractures in the high-lumbar group frequently result in dislocated hips. The mid- and low-lumbar groups often have hip and knee flexion contractures, increased lumbar lordosis, and overpronated feet. Patients in the sacral group often exhibit mild hip and knee flexion contractures and increased lumbar lordosis with various ankle and foot positions (Brown, 2001).

Scoliosis or curvature of the spine can be congenital or acquired. The congenital form is associated with underlying spinal anomalies. The acquired form develops in 40-60% of children with myelomeningocele and is related to muscle imbalances. Increased lumbar lordosis and kyphosis of the entire spine or localized to the lumbar region also are observed. All the spinal deformities occur more frequently in groups with higher spinal lesions (Shure, 1993).

Ocular muscle palsies, swallowing and eating problems, and abnormal phonation are signs of cranial nerve dysfunction. These symptoms may be related to Arnold Chiari II malformation, hydrocephalus, and/or abnormal brainstem growth (Hunt, 2003).