Dural sac
As dural sac or dural sac in the clinical usage of the tube (from dura mater is mater Dura ) denotes that the spinal cord and the outgoing nerve roots surrounds. Anatomically, this name is not completely correct, as it does not take into account that the so-called spider web skin ( arachnoid ) is also involved in the formation of this covering. The dural sac ends at the level of the second sacral vertebra in the filum terminale .
function
The dura mater is a solid covering that is supposed to protect the highly sensitive nerve tissue of the spinal cord against mechanical damage. At the exit of the nerve roots, the dura forms a protuberance, called a root pocket, which accompanies the nerve root and only then merges into the connective tissue covering of the nerve, the epineurium . In addition, the dural sac is filled with cerebrospinal fluid ( liquor cerebrospinalis ), and here, too, a protective function is assumed, this time in the sense of a water pillow.
Pathological changes
Scarring after disc surgery can of a bond between the dural sac and the inner region of the spinal canal lead, resulting from such complaints are the discectomy syndrome attributed. If the dura mater is injured, spinal fluid drains off, which is particularly important in an upright posture as a result of the hydrostasis. The resulting negative pressure inside the skull capsule leads to swelling of the brain with resulting headaches. This is called CSF loss syndrome and sometimes occurs as a result of punctures or injections into the dural sac.
Clinical significance
The dural sac offers a very simple way of accessing the liquor space through puncture. The laboratory analysis of the spinal cord fluid can provide information with regard to the diagnosis of a number of diseases. However, it is just as possible to inject an X-ray contrast medium into the dural sac and thus determine space occupation within the spinal canal, but also pathological changes in the nerve roots or in the spinal cord itself. With the high level of technical development in computed tomography and nuclear magnetic resonance diagnostics that has now been reached , this X-ray contrast display or myelography is becoming increasingly rare. It is also common to inject drugs directly into the dural sac as a way to completely numb the lower half of the body ( spinal anesthesia ) in order to be able to perform operations here. In obstetrics, an anesthetic is usually only introduced into the space between the dura and the spinal canal ( epidural anesthesia ).
In the case of very severe pain, opiates are often the only remaining option to make life bearable for the person affected. If these opiates are introduced directly into the dural sac, vanishingly small doses are sufficient to achieve satisfactory pain relief. There are permanent catheter inserted over which the drug can be administered continuously at a drug pump.
