grade I : involves grey-white matter interfaces most commonly : parasagittal regions of frontal lobes, periventricular temporal lobes less commonly : parietal and occipital lobes, internal and external capsules, and cerebellum often inapparent on conventional imaging may have changes on MRS 3
grade II : involves corpus callosum in addition to stage I locations observed in approximately 20% of patients most commonly : posterior body and splenium but does advance anteriorly with increasing severity of injury most frequently unilateral may be seen on SWI 3
grade III : involves brainstem in addition to stage I and II locations most commonly : rostral midbrain, superior cerebellar peduncles, medial lemnisci and corticospinal tracts.
When Brainlab first introduced neurosurgery software in 1989, a neurosurgeon who needed software was viewed as not a good neurosurgeon. Today, a neurosurgeon who does certain procedures without the proper software is viewed as not a good neurosurgeon.
The initial ProDisc-L artificial disc was developed by Thierry Marnay 2) in 1989, and was used clinically in the early 1990s. Subsequently, the second generation, ProDisc II was developed in 1999 with cobalt chrome endplates and constrained polyethylene core and approved for commercial use in Europe the same year.