SPINA BIFIDA OCCULTA – WHAT IS ITS SIGNIFICANCE?

The two cases presented here demonstrate the benign presentation of spina bifida occulta. There is a benign spina bifida occulta affecting the C7, T1 and T2 segments without evidence of block vertebrae or congenital fusion. In the cervical spine most cases of spina bifida occulta are not symptom generating and are not associated with any other abnormalities. However, if spina bifida occulta should occur at C5 or C6 as an isolated entity it may be associated with true cervical spondylolisthesis with lack of development of the pars–lamina area. The additional case here demonstrates spina bifida occulta at L5 which carries a higher incidence of an association with pars defects and/or spondylolisthesis. Many patients with benign spina bifida occulta at L5 do not have spondylolisthesis but many do. So, when viewing spina bifida occulta at L5, one should always look very closely for defects in the pars and if necessary, obtain oblique radiographs to rule out a pars interarticularis defect.

AZYGOS FISSURE

Observe the curvilinear radiopacity seen in the medial aspect of the right upper lobe. This is the classic characteristic appearance of an azygos fissure creating what has been referred to as an azygos lobe. The fine radiopaque line present in the right upper lung apex represents the azygos fissure. The radiopaque density at the base of the fissure represents the azygos vein. This fissure creates an accessory lobe that is often referred to as the azygos lobe. This is of no clinical significance to the patient and no further imaging is necessary.

A SIMPLE CASE HISTORY: SOLVES THE PROBLEM

Observe the extensive bone deformity present affecting this patient’s left ilium. At first glance one might consider this could be a destructive or expansile neoplasm such as chondrosarcoma, plasmacytoma or possibly metastatic disease. A detailed history of this patient helped answer this question. This patient had a giant cell tumor in the distal tibia that has been treated with a bone graft taken from the patient’s ilium. Without that history it would be very difficult to make that conclusion. Bone grafts are often taken from the posterior aspect of the ilium rather than the anterior surface. While this deformity is quite extensive in this patient, it was asymptomatic.

Also noted were metallic clips present in the proximal scrotum. This patient has had a previous bilateral vasectomy. Note on the lateral film there is multilevel discogenic spondylosis with advanced disc space narrowing at every lumbar segment.