Glossary

O6-methylguanine – this is a naturally occuring protein (alkylated guanine) that induces DNA mutations and it is removed by MGMT. It is felt to be carcinogenic.

Occipital Frontal Circumference. The circumference of the largest part fo the head.  A flexible, non-stretchable measuring tape measures the circumerference from just above the eyebrows to the most prominent part of the back of the head.

Having few symptoms.  A paucity of symptoms.

Oncosphere: The larval form of a tapeworm that has been ingested by an intermediate host animal.

Overall survival.  This term is used to define the time until death after a treatment.

over-the-counter, as in over-the-counter drug.  A medication obtained without prescription legally.

Posterior Atlanto-Dental Interval.  This is the horizontal distance from the posterior (dorsal) odontoid surface to the anterior (ventral) surface of the posterior arch of the atlas. This measures the  space available for the spinal cord (so-called SAC).  A value of less than 13 mm suggests cord compression.

– aka dorsal midbrain syndrome: Abnormalities in eye movement and pupillary function die to a lesion in the midbrain. The abnormal eye movements associated with this syndrome are paralysis in upgaze, paresis in accommodation with convergence-retraction nystagmus and sunsetting due to retraction of the upper eyelids (sun setting).

pB-C2 line – Also referred to as the Grabb-Oakes line. A line drawn through the odontoid that is perpendicular to a line extending from the posterior basion to posterior-inferior body of C2. The distance of the segment of this line from the anterior edge of the odontoid to the ventral dura represents the degree of encroachment of the odontoid into the upper spinal canal and potential ventral brainstem compression.

Posterior Communicating Artery – An artery that is part of the Circle of Willis at the base of the brain that provides a circulatory pathway between the Carotid Artery and the Posterior Cerebral Artery.