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Ossification of the Posterior Longitudinal Ligament
OPLL
General Considerations
- Heterotopic ossification of the posterior longitudinal ligament
- Occurs primarily in cervical, most often C4-C5, next most commonly in thoracic spine and least frequently in lumbar spine
- Most commonly in 40s and 50s
- Twice as common in males as females
- Higher prevalence in Asian population, especially Japanese
- Since OPLL can narrow the spinal canal, most who are symptomatic present with spinal stenosis or myelopathy
- Associated with DISH
Clinical Findings
- Majority of patients have no symptoms
- Cervical myelopathy is the most common presentation
- Numbness
- Neck pain
- Weakness
Imaging Findings
- Linear ossification immediately posterior to vertebral body in canal
- May be continuous (spans several bodies and intervening disc spaces), segmental (occupies back of body but spares disc spaces) or both
- Predominantly in high cervical spine
- CT is best at demonstrating ossification
- On MR, signal behind the vertebral bodies and interbody spaces becomes less dense on all MR imaging sequences as disease progresses
Differential Diagnosis
- Calcified herniated disc
- Calcified meningioma
- Calcified epidural hematoma
Treatment
- Symptomatic patients may undergo decompression such as by laminectomy
Prognosis
- Patients with mild cases of OPLL on first discovery rarely progress to severe stenosis
- Patients presenting with myelopathy are likely to progress
Ossification of the Posterior Longitudinal Ligament (OPLL). Above:Linear ossification just posterior to the posterior border of the cervical vertebral bodies (white arrows). Below: Sagittal reconstruction of cervical spine CT on left shows same flowing ossification (yellow arrow); axial CT demonstrates the ossified posterior longitudinal ligament (blue arrow).
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Inamasu J et al: Ossification of the posterior longitudinal ligament: an update on its biology, epidemiology, and natural history. Neurosurgery. 58(6):1027-39; discussion 1027-39, 2006
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