A radiographic appearance involving the spine in which linear or circular radiolucent collections appear within the intervertebral discs.
In persons with intervertebral osteo chondrosis this finding is accentuated with extension and may disappear with flexion. Vacuum phenomena are a reliable indicator of disc degeneration and are very rare in the presence of discal infection or tumour. These phenomena are of various types and may be seen in several diseases or conditions.
Vacuum phenomena are a characteristic, although not pathognomonic, sign of intervertebral (osteo)chondrosis.
When isolated in the outer portions of the anulus fibrosus the vacuum phenomenon represents early findings of Spondylosis deformans. Similar gaseous collections have been noted in the discs of the cervical spine after trauma. Displacement or herniation of portions of a degenerating intervertebral disc into the spinal canal can also be associated with gas formation in both the disc and the canal.
An intraosseous vacuum phenonemon may occur after fracture and fragmentation of vertebrae in patients with Ischaemic necrosis, particularly those taking steroid medications.