Dr Adriaan Liebenberg My Spine Explained | Page 124

My Spine Explained
Thecal sac – This is the name given for the elongated membraneous tube that
extends from the brain to the end of the spine in which the spinal cord and
nerve roots run. It is made up of – and is continuous with – the membrane that
covers the brain.
Flattening of the spinal cord – This is a description of the situation that
occurs when a herniated (slipped or prolapsed) disc has extended so far into
the spinal canal that it is pushing on the spinal cord.
Flattening of the thecal sac – This is a description of the situation that occurs
when a lumbar herniated (slipped or prolapsed) disc has extended so far into
the spinal canal that it is pushing on the thecal sac.
Nerve root – The nerve root leaves the spinal cord, or the thecal sac in the
lumbar area, and exit the spine through the intervertebral foramen. Most of
the exiting nerve roots can be seen side-on in the axial planes as well as the
coronal planes and are seen end-on in the sagittal plane.
Foraminal stenosis – This is a narrowing of the foramen and the exiting
nerve root can become compressed in the foramen by either a disc herniation
or a hypertrophied facet joint or a combination of both.
Synovial cyst – The joint space of the facet joints are lined with a membrane
– the synovial membrane – which allows for free and easy movement of the
joint. Sometimes, as the joints become damaged, this synovial membrane can
bulge out and form a cyst.
The cyst is filled with synovial fluid that is usually found in the joint space
for lubrication. These are completely benign (harmless) lesions and should
not be confused with cancerous lesions. They can, however, cause nerve com-
pression and foraminal stenosis.
Tarlov cyst – This cyst is filled with spinal fluid and develops in the mem-
brane that covers the nerve roots. If it is large, it can cause nerve compression
and pain. Surgery for this benign lesion can be difficult. The diagnosis is
made based on the fact that the cyst is in direct contact with a nerve root.
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