Evaluation of Degenerative Lumbar Disk Disease in Children

Examination

Similar to the adult population, diagnosis and treatment planning for children is very dependent on the patient’s history and physical findings.

• Aggravating movements: Activities or positions that worsen or improve the symptoms should be determined, with particular attention to whether or not the pain is motion-dependent. The range of motion should be examined to assess for flexion, extension, lateral bending, and rotation. Limitations may be pain-induced or related to seronegative spondyloarthropathies.
• Time frame of evolution: The time course and timing of pain are also important, as rapid progression raises concerns about diskitis or tumor. Similarly, pain at night or awakening the child from sleep is more concerning for tumor.
• Alteration of routine: It should be determined how much the pain is actually interfering with the child’s activities or attendance at school. Because children do not routinely have aches and pains, many will present (or be presented by their parents) with pain that does not significantly impact their daily lives. What these families need most is the reassurance that there is no imminent life-threatening danger.
• Tenderness, kyphoscoliosis: Physical examination should include assessment for tenderness, location of tenderness, and examination from the side and back to assess for scoliosis (i.e., Adam’s forward bending test) and kyphosis. More paramedian pain may reflect myofascial pain.
• Neurological examination: A complete motor examination should be performed. Evaluation of foot inversion/dorsiflexion/extensor hallucis longus (L5) and foot eversion/plantar flexion (S1) may help to distinguish a peroneal nerve injury from a radiculopathy. Reflexes should be examined; a complete sensory examination assessing dermatomal distribution should be performed, as well. If clinical concern for cauda equina is raised, a rectal examination assessing for tone is important.
• Specific tests: A straight leg raise (Lasegue) test should be performed. Other provocative clinical tests may be considered, such as a FABER (flexion abduction external rotation), to assess for sacroiliac joint pathology.

Laboratory Tests

In straightforward cases of DDD, laboratory tests are mostly reserved for preoperative screening. However, they can be helpful in differentiating from other diseases.

• Screening for infection: If infection is suspected, then a WBC count with differential, ESR, and CRP can be helpful. Blood cultures should be performed, although these are helpful only if they are positive.
• Serology for arthritis/inflammatory processes: If JRA is suspected, adding ANA and RF titers may be helpful. HLA-B27 testing may be used if a pretest suspicion is present for seronegative spondyloarthropathy.

Radiologic Tests

When to obtain imaging: Routine imaging is not required for initial evaluation and management of LBP if no red flags are present. Typically, imaging is reserved for refractory symptoms, recurrence, or in the presence of clinical suspicion for alternate diagnoses listed above.

Radiographs

• X-rays: AP, lateral, and oblique radiographs should be obtained to assess for pathology. The oblique views provide a more reliable assessment of the pars interarticularis to visualize a pars defect.

Oblique lumbar spine x-ray of fractured pars: X-ray of a 17-year-old with a pars defect (black arrow) highlighting a “broken Scotty-dog neck”.

• Flexion-extension x-rays: Dynamic x-rays (i.e., flexion-extension x-rays) may provide additional information if there is abnormal movement or if a spondylolisthesis has increased subluxation with movement.

Extension lateral x-ray of spondylolisthesis: Seen is reduction of the listhesis in a 10-year-old boy with spondyllithesis.

Flexion lateral x-ray of spondylolithesis: With flexion, the boy’s spine now shows an anterior listhesis of L5 on S1.

• CT: CT imaging should be performed when a clinician wants to better visualize osseous anatomy. Indications for CT may include but are not limited to the following: if a pars defect is suspected but not identified on radiographs; evaluation of a fracture or suspected fracture; diagnosis or follow-up for osseous tumors (e.g., osteoid osteomas); preoperative planning if congenital anomalies are present or if instrumentation is planned; addition of contrast to follow tumors. CT myelography can also be obtained to assess neural or intraspinal anatomy if MRI is contraindicated.

Sagittal CT image in a 9-year-old with back pain and histiocytosis of the L4 vertebral body: Shown is the osseous erosion by the histiocytosis.

Axial CT scan of histiocytosis: Shown is the extent o involvement of the L4 level by the histiocytosis.

• MRI: MRIs should be obtained to better visualize neural anatomy and routinely can be used for assessment and follow-up of infectious etiologies, neoplastic growths, and congenital anomalies.

Sagittal T2-weighted MRI of a disc herniation in a 17-year-old with right-sided L5 radiculopathy.: Seen is a small disk herniation (white arrow). 6 months of conservative treatment failed to result in resolution of the radiculopathy.

Axial T2-weighted MRI of L4-5 disk herniation: The white arrow points to the small disk fragment compressing the right L5 nerve root.

Nuclear Medicine Tests

• Conditions causing increase metabolism: Nuclear medicine tests may be used to help identify more indolent or subtle infections, inflammation, or degenerative changes. They will highlight areas with increased metabolic activity, which may represent infection, inflammation, or spondylolysis.

Electrodiagnostic Tests

• Electrodiagnostic testing: EMG and NCS may demonstrate signs of radiculopathy, including increased F-wave latencies and muscle denervation. Occasionally, this can be helpful in making a diagnosis or treatment plan.

Correlation of Tests

• DDD: The clinical findings should be used to create a diagnosis corroborated by imaging findings. Radiographs may show loss of height of the disk space or degenerative changes at the endplates. MRI may show Modic changes dependent on the chronicity of changes and should be used to visualize compression of the affected nerve root from the disk or foraminal compression. Occasionally, a high-intensity zone (HIZ; bright T2-weighted spot suggestive of edema within the annulus fibrosus) may be visualized, reflecting an annular tear.