TABLE 17-3. ROSTROCAUDAL BRAIN STEM DETERIORATION SECONDARY TO EXPANDING RIGHT SUPRATENTORIAL MASS
ANATOMICAL LEVEL (the level reached by progressive damage) |
CONSCIOUSNESS |
RESPIRATION |
PUPILS |
OCULOMOTOR-VESTIBULAR |
MOTOR |
Upper diencephalon |
Drowsy (dull) |
Eupnea with yawns and sighs |
Small, reactive |
Depression of ocular checking and fast component of nystagmus |
Left hemiparesis, bilateral paratonia |
Lower diencephalon |
Coma |
Cheyne-Stokes (CSR) |
Small, reactive |
Loss of above |
Left hemiparesis, decorticate |
Mesencephalon |
Coma |
CSR or central neurogenic hyperventilation (CNH) |
Midposition, fixed (MPF) |
Dysconjugate response; loss of medial rectus function on horizontal gaze; may see loss of lateral rectus function also (see text) |
Decerebrate |
Upper pons |
Coma |
CNH or ataxia |
MPF |
As above |
Weak decrebrate |
Lower pons |
Coma |
Ataxia or apnea |
MPF |
None |
Flaccid, areflexic |
Medulla |
Coma |
Apnea |
MPF |
None |
Same |