Cord pathology

Cord pathology include the following:

1-Tethered cord.

2-Diastematomyelia.

3-Syrinx.

These are the three sub items related to cord pathology in addition to Ventricularis terminalis which is a distal oval dilatation of the conus medullaris.

1-month-old boy with ventriculus terminalis who was referred for deep sacral dimple and who is developmentally normal at 18 months. Sagittal T2-weighted MR image at age 7 months shows stable distention of distal spinal canal (arrowhead), excluding syrinx.

1-Tethered cord:

-Normally the cord is stopped at the level of L1-L2.

-If it extends below this level, it is considered to be a tethered cord.

-After birth, the cord is present down to that level, then it start gradually to goes up as the filum terminalis is soft and permits that raising up, if filum terminalis is tight , it will inhibits this rising leading to formation of tethered cord.

-Tethered cord is one of the most famous type of dysraphysm and almost in this cases you will find a small lipoma causing tightness of the filum resulting in its stiffness and formation of the tethered cord.

-D.D.between lipoma of filum and lipomeningomyelocele is that in the former the lipoma is present in the filum and not attached to another one in the subcutaneous area.

In this T1 image the cord is tethered with evidence of a lipoma present intra dural.

Tethered cord with evident lipoma at the end of the cord.

-Sometimes, you can find tethered cord with lipoma in the filum.

Tethered cord without lipoma.

Tight filum syndrome:

-Tethered cord by a thickened filum terminale.

-The filum may be lipomatous or fibrous.

-Normal thickness of the filum(2 mm).

-Normal cord termination with thickened filum is seen in 50% of cases.

2-Diastematomyelia:

-Due to partial or complete, bony or fibrous sagital cleft.

-90% affects female.

-90% have tethered cord.

-100% have spina bifida.

-The septum may be present or not, and when it is present it could be bony or fibrous.

-Usually, there is a cutaneous stigma(Faun tail). which is most commonly a long silky patch of hair known as Faun tail. 

Faun tail.

Diastematomyelia with bony cleft (type 1).

Diastematomyelia (type 2 ).

Diastematomyelia with bony cleft (type 1).

-Cleft could be due to presence of a bone or fibrous tissue or could be  without anything.

-Types of Diastematomyelia:

*Type 1:There is evidence of a mid sagittal bony or fibrous spur separating the spinal cord into two parts, each with its own arachnoid and dural sheath. 

*Type 2: Has no spur and the hemi cord lie within a single arachnoid and dural sheath.

Type 1

3-Syrinx:

-Hydromyelia is dilatation of the central canal lined by ependymal cells.

-Syringomyelia is lined by glial cells and is due to trauma.

- It is so difficult to differentiate between both, so it is known as syringohydromyelia.

-Syrinx is can be found in children without problem, but if you feel that it is due a tumor you must give contrast.