Vacuum Phenomenon in the Lumbar Spine: Pilot Study for Accuracy of Magnetic Resonance Imaging.

Objectives: Vacuum phenomenon (VP) is defined as air within a joint. Many pathologies are associated with VP, mainly degenerative disease and trauma. Although patients with intradiscal gas may be asymptomatic, it promotes disc degeneration and can eventually become painful.

Dorsal Arachnoid Web: A Rare Cause of Myelopathy.

The scalpel sign is pathognomonic for a dorsal arachnoid web, a rare clinical-radiologic entity that can cause myelopathy.

Retro-Odontoid Pseudotumor in a Patient with Atlanto-Occipital Assimilation.

A retro-odontoid pseudotumor is an uncommon non-neoplastic mass. They are mostly associated with rheumatoid arthritis and atlanto-axial subluxation. The pathogenesis is degeneration of the transverse ligament due to chronic mechanical stress.