Magnetic resonance imaging study of the level of termination of the Conus Medullaris and the thecal
sac: influence of age and gender.
The space between the outer margins of the vertebral canal and the thecal
sac is the epidural space which contains fat and blood vessels.
If there is concern for intrathecal needle placement, check for CSF return or look for a myelographic appearance during contrast administration: on the depth view, small intrathecal injections will first fall dependently and outline the anterior thecal
sac (Figure 10).
The observed sonographic changes within the spinal canal at the level of needle insertion during the loss of resistance are the anterior displacement of the posterior dura and widening of the posterior epidural space and compression of the thecal
sac (10, 35).
The ovary remains the primary source of hyperandrogenism in women with PCOS which is mainly attributed to thecal
cell hyperplasia leading to intense ovarian steroidogenesis.
At T10-T11, a small right central disc protrusion resulting in mild deformity of ventral thecal
sac, but no spinal cord impingement, was observed.
T1- and T2-weighted images revealed an intradural, extramedullary heterogeneous subdural T2 signal and isointense T1 signal located ventral to the spinal cord spanning T8 to T11 causing displacement and compression of the thecal
sac consistent with hyperacute or acute subdural hematoma.
Lumbar canal stenosis leads to compression of the thecal
sac and may also involve the nerve roots because of narrowing of the intervertebral foramina.
MRI revealed an epidural abscess from T5-6 to T8-9 causing mild thecal
cord compression and a collection from L4 to S1 (see Figures 1(a) and 1(b)).
Franks, "Evidence for a primary abnormality of thecal
cell steroidogenesis in the polycystic ovary syndrome," Clinical Endocrinology, vol.
Caption: FIGURE 3: Axial T2 postinjection MRI demonstrating extradural hydrogel sealant deposition with lefward displacement of the thecal
sac and spinal cord at T10-11.