12 CN IV injuries Intrinsic Trauma Tumor Demyelination Vascular MedulloblastomaEpendymomaMetastaticDemyelinationVascularCongenital ( high vertical vergence amplitudes and objective excyclotorsion only)Bilateral: V-pattern esotropia and excyclotorsion greater than 15 degrees.Resultant compensatory head position?
14 Skew Deviation? Supranuclear cause of vertical misalignment Does not necessarily obey the 3-step testIpsilateral intorsion (not extorsion as in IV palsy)Interruption of otolith-ocular pathway at some point along it’s course
15 Skew deviation - OTR Vestibulo-cerebellar: Midbrain: Ipsilateral head tiltIpsilateral hypotropiaExcyclo of hypo eye, incyclo of hyper eyeMidbrain:Contralateral head tiltIpsilateral hypertropiaExcylo of hypo eye, incyclo of hyper eye
28 Paramedian Pontine Reticular Formation Horizontal Gaze centerInitiates horizontal eye movementsBilateral, within PonsProjects to ipsilateral CN VI nucleusLesions of the PPRF cause ipsilateral gaze palsiesPPRF lesions do not affect oculocephalic & caloric reflexes
30 MLF Midbrain to cervical spine Composed of interneurons – ipsilateral CN VI to contralateral CN III.fascicle for horizontal gaze and vertical gaze that connects the VI and III nuclear complexes.Trochlear nerve and otolith ocular pathways also use the MLF
31 Vertical GazeRostral Interstitial nucleus of the MLF (riMLF) (gaze initiation)Interstitial Nucleus of Cajal (INC) (gaze holding)INCriMLF
32 UpgazeLateral riMLF projects to contralateral inferior oblique and superior rectus sub-nucleiRemember Superior Rectus fascicle decussates
34 DowngazeMedial riMLF projects downward to ipsilateral superior oblique and inferior rectus sub nucleiRemember the CN IV fascicle decussatesVertical gaze is initiated by Bilateral activation of the riMLF and INC.