Ossification of the posterior atlantoaxial membrane associated with atlas hypoplasia: A case report

Ossification of posterior atlantoaxial membrane causing spinal stenosis - A case report

Background

Ossification of the posterior atlantoaxial membrane (PAAM) is a rare cause of spinal cord compression.

Case presentation

A 46-year-old woman with rheumatoid arthritis (RA) and a 2-year history of slowly progressive gait disturbance underwent surgery for right knee stiffness and right lower limb mild weakness. A neurologic examination revealed brisk deep tendon reflexes (DTR) and spasticity in her four limbs. A computed tomography (CT) scan revealed spinal stenosis caused by ossification of the PAAM, a rare cause of spinal cord compression. The patient's lower limbs weakness and walking capability were ameliorated post-surgery.

Conclusions

Although the exact mechanism of ossification of PAAM remains unclear, chronic mechanical stress as well as persistent atlantoaxial instability may promote the development of the ossification.

Hypoplasia of C1's posterior arch: Is there an ideal anatomical classification?

Background:

Congenital anomalies of the atlas are rare and usually occur in conjunction with other congenital variants. They include a wide spectrum of anomalies ranging from clefts to hypoplasia or aplasia of its arches that may contribute to spinal cord compressive syndrome.

Case Description:

A 54-year-old male presented with the sudden onset of a severe quadriparesis and loss of proprioception after a minor fall. The magnetic resonance (MR) scan showed cord compression at the C1 level attributed to C1 arch hypoplasia. Two months following a decompressive C1 laminectomy without fusion, and the patient was symptom free.

Conclusion:

Posterior C1 arch hypoplasia is a rare anomaly that can contribute to cervical cord compression and myelopathy. The optimal surgical management may include, as in this case, a posterior decompression without fusion.

Concurrent Ossification of the Posterior Atlantoaxial Interlaminar Membrane and Atlas Hypoplasia: A Case Report

An onset of cervical myelopathy due to ossification of the posterior atlantoaxial membrane (PAAM) is extremely rare in older patients, and its clinical characteristics are still unclear. We report an onset of ossification of PAAM with congenital atlas hypoplasia in an 81-year-old man who presented with a 2-year history of progressive cervical myelopathy. Cervical computed tomography (CT) revealed canal stenosis secondary to a hypoplastic posterior arch of the atlas with a diameter of 20.3 mm between the anterior and posterior process. Magnetic resonance imaging showed marked spinal cord compression at the level of C1-2 secondary to atlas hypoplasia as well as ossification of PAAM. The patient underwent laminectomy of C1 and partial C2, as well as removal of the ossification, without atlantoaxial fusion. His neurological status improved 1 year postoperatively. In older patients, cervical myelopathy secondary to PAAM ossification, in the absence of trauma and atlantoaxial instability, may be induced by age-related pathophysiology associated with congenital atlas hypoplasia.