Spinal Cord Tethering

Central to an understanding of the development of symptoms in occult dysraphism is the concept of spinal cord tethering. This is a dynamic problem with the spinal cord and cannot therefore be identified per se on static imaging such as MR or CT. Nevertheless, that tethering may exist can be inferred by the presence of an abnormality such as a lipoma, bony spur or thickened filum terminale, producing an abnormally long spinal cord with a low-lying conus. The implication is that the cord has been held in its original position and prevented from ascending within its thecal sac during growth of the individual. There are a number of possible explanations of why this should lead to neurological dysfunction:

sustained traction on the cord with growth of the bony spine leads to stretching of the cord itself and disruption of neuronal function;

ischemia of the cord leads to abnormalities of oxidative metabolism [13]; repeated hyperflexion (e.g. during sporting activities) of the spine causes acute injury to neuronal processes at the level of the tethering lesion.

Attempts have been made to "visualize" tethering clinically using MR CSF pulsatility studies [14] or to demonstrate motion of the conus using CT myelography in both prone and supine positions, but the diagnosis remains a clinical one, based on the presence of a presumed tethering lesion and evidence of neurological dysfunction.

If tethering is the underlying cause of neurological deterioration in many dysraphic conditions, the principle of surgical treatment is to untether the spinal cord and to prevent it re-tethering. This is generally achieved by removing the tissue responsible for the tethering or detaching the spinal cord from it, as described in the specific sections below.

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The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.

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