Glossary

A technique for increasing imaging contrast between dissimilar tissues.  Biological tissues attenuate X ray beams to differing extents depending on (a) the nature of the tissue and (b) the energy of the X ray beam. First generation CAT scanners used X ray at a single energy level. By using two X ray sources, at differing energy levels (dual energy technique), contrast definition between tissues and therefore image resolution can be improved.

A condition where abnormal cranial nerve development results in a limited ability to move the eyes outward. There is also abnormalities in the bones of the hands or absent thumbs, extra thumbs and absent of the bones of the forearm to a varying degree.

Refers to the repair or expansion of the dura (the outer covering of the central nervous system).  In the case of its referring to expansion, this can be accomplished using an artificial substance or tissue obtained from elsewhere in the patient’s body that is “grafted” into the opening of the dura.

Developmental venous anomaly (aka – cerebral venous angioma) – a developmental anomaly consisting of a collection of veins draining into a single larger collecting vein, which in turn drains into either a dural sinus or into a deep ependymal vein. The appearance has also been likened to a palm tree. They are the most common cerebral vascular malformation (range 50-63%).

Deep vein thrombosis – refers to clotting within the deep veins of the body, typically those of the extremities and in particular the legs.

Diffusion weighted imaging – A type of MRI that is thought to image water molecules diffusing across an area of tissue being imaged. It is thought to be sensitive to early pathological changes in tissue. This type of scan is most useful in tissue the grey matter of the central nervous system

An inability to perform rapid, alternating muscle movements (diadochokinesis).

Dyskinetic = abnormal movement.  Cerebral palsy characterized by abnormal movements that can be slow, writhing or fast and jerky.  Types of dyskinetic CP are athetoid CP, chorea CP, and dystonic CP.

A movement disorder consisting of involuntary muscle contractions that result in slow, repetitive movements and/or postures.

External Carotid Artery