The term 'vacuum phenomenon' (VP), is characterized by gas-like density areas due to a rapid increase in the joint space volume ('acute VP') or represent a chronic gas collection. It can occur within a collapsed vertebral body, the spinal canal, joints but mainly the intervertebral disc. Studies support that VP is originated by a dynamic process involving the balance between tissues' liquid and gaseous components, influenced by the duration and the depth of mechanical and metabolic alterations, by the nature of neighboring tissues and the variability in both pressure and permeability of disc or vertebral or joint structures. Prevalence of VP in the general population is about 2%, reaching 20% in the elderly with disc degeneration. Although it's often a random finding in asymptomatic patients, VP is an eventually painful expression of disc degeneration, or disc or vertebral fracture, or bone lesions. In sporadic cases, intradiscal gas can be expelled (all-in-one or gradually), resulting in a gaseous cyst, causing pain and neurological symptoms. Considering that spontaneous resolution and recurrence after surgery are both possible, most of the authors recommend conservative treatment in patients with intradiscal and intravertebral VP; occasionally percutaneous CT(computed tomography) -guided aspiration or vertebral stabilization.
Keywords: Vacuum; back pain; intervertebral disc; intravertebral fracture; pathogenesis; physiology; pneumorrhachia; spine disease.