Oculomotor abnormalities in brainstem lesions

Oculomotor Abnormalities in Brainstem Lesions

Hyun Ah Kim

Department of Neurology Keimyung University Dongsan Hospital, Daegu, Korea

Oculomotor abnormalities in brainstem lesions

Keimyung University Dongsan Hospital Department of Neurology Hyun Ah Kim

Lateral medullay infarction (LMI)

 Vestibular nucleus

 Sympathetic tract

 Inferior cerebellar peduncle

Vestibular nucleus

Extraocular motor

Horizontal neural

Medial medullay infarction (MMI)

NPH

(nucleus prepositus hypoglossi)

Vertical VOR or neural integrator !!

Horner’s syndrome

Spontaneous nystagmus (vestibular nucleus)

: contralesional mixed horizontal-torsional N (rostral lesion) : ipsilesional mixed horizontal-torsional N (caudal lesion) : vertical component – usually upbeat

: pure torsional nystagmus Horizontal gaze-evoked nystagmus

: medial vestibular nucleus (MVN) Ocular ipsipulsion

Ipsilesional OTR

Ipsilesional head-shaking nystagmus

Ophthalmological findings in LMI

Spontaneous nystagmus

: ipsilesional mixed horizontal-torsional nystagmus (nucleus prepositus hypoglossus: NPH) : upbeat nystagmus

(bilateral AC or nucleus intercalatus/Roller) : hemi-seesaw nystagmus

Gaze-evoked nystagmus

: horizontal GEN (ipsi-gaze >> contra-gaze) - nucleus prepositus hypoglossus (NPH) : vertical GEN (NPH connection to INC) Ocular contrapulsion

Contralesional OTR

Ophthalmological findings in MMI

(dysruption of bilateral anterior canal pathways or nucleus intercalatus/Roller)

Hemi-seesaw nystagmus in MMI

Contralesional OTR Ocular ipsipulsion

(+) (-)

(-)

Ipsilateral saccadic hypermetria Contralateral saccadic hypometria Impaired contralateral pursuit

Ocular contrapulsion

Inverse Ptosis in Horner Syndrome : Sun rising Sign

Responsible structures for

abnormal ophthalmological findings in pontine lesion

MLF PPRF lesion 6th nucleus lesion 6th nerve fascicle

Central tegmental tract (CTT) Paramedian tract (PMT) DLPN, NRTP Ocular bobbing

Smooth pursuit VOR PPRF

Clinical Features of Internuclear Ophthalmoplegia (INO)

Weakness of the ipsi. MR for conjugate eye movements : especially saccades, leading to “adduction lag”

Adduction may be preserved during convergence

Nystagmus or postsaccadic drift on abduction of the eye contralateral to the lesion : “dissociated nystagmus”

Skew deviation—hypertropia on the side of the lesion

Bilateral INO also causes gaze-evoked vertical nystagmus, impaired vertical pursuit, and decreased vertical vestibular responses

Small-amplitude saccadic intrusions may interrupt fixation

33 patients with dissociated torsional–vertical nystagmus and INO. 

11 (33%): ipsiversive torsional in both eyes with vertical components in the  opposite directions  

18(55%): ipsiversive torsional nystagmus with a larger upbeat component in the  contralesional eye  

4(12%): ipsiversive torsional nystagmus with a greater downbeat component in the  ipsilesional eye 

The patterns of jerky seesaw nystagmus in INO suggest a disruption of neural  pathways from the contralateral vertical semicircular canals with or without  concomitant damage to the fibers from the contralateral utricle in or near the  medial longitudinal fasciculus.

Conjugate Horizontal gaze palsy

PPRF lesion Abducens nucleus lesion

Isolated ipsilesional saccadic palsy with contralesional conjugate deviation of the eyes Isolated PPRF or abducens nucleus lesion: rare

DDx. 6th nulear lesion from PPRF lesion : Impairment of saccades, smooth pursuit, VOR : normal centripetal saccades from contralateral side

(mild slowing is also possible) : associated peripheral facial nerve palsy

PPRF lesion, Rt

Courtesy of Kwang-Dong Choi

Abducens nucleus lesion, Lt

Courtesy of Kwang-Dong Choi, Ji Soo Kim

HIT

One-and-a-half syndrome

Guillain-Mollaret Triangle (Dentate nucleus, Red

nucleus, Inferior Olive) – Oculopalatal tremor Pontine ICH and inferior olivary hypertrophy

Video

Ahn BY, Choi KD, Kim JS, et al. Neurology, 2007

PMT : the cell group of the paramedian tracts DLPN : dorsolateral pontine nucleus – initiation (FEF : dorsal vermis)

NRTP : nucleus reticularis tegmenti pontis – maintenance (MT and MST : flocculus and paraflocculus )

The dorsolateral pontine nuclei (DLPN) and the nucleus reticularis tegmenti pontis (NRTP) are involved in the control of smooth pursuit eye movements.

Damage to DLPN impairs ipsilesional smooth pursuit (May et al., 1988; Ahn et al., 2007), and NRTP lesions cause impairment of vertical smooth pursuit (Suzuki et al., 1999) and vergence eye movements (Gamlin and Clarke, 1995;

Rambold et al., 2004).

Ocular bobbing after pontine hemorrhage

Courtesy of David Zee

Intermittent, conjugate, fast downward eye movements followed by slow upward return to  primary position. 

It usually localizes to intrinsic pontine pathologies (stroke, tumor) , although it has been  described in extra‐axial masses, diffuse encephalitis, toxic and metabolic encephalopathies.

Video

Responsible structures for

abnormal ophthalmological findings in midbrain lesion

Rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) Interstitial nucleus of Cajal (INC)

Posterior commissure and the nucleus of the posterior commissure Premotor neuron of vergence

Oculomotor and trochlear nucleus Medial longitudinal fasciculus (MLF)

riMLF

Bilateral lesion

Vertical and torsional saccades are abolished

Vertical pursuit, VOR and gaze holding as well as horizontal saccades are spared Unilateral lesion

Mild slowing of downward saccades Static contralesional torsional deviation

Torsional nystagmus beating contralateral to the side of the lesion Loss of ipsitorsional quick phases

Selective saccadic loss

RiMLF

Kremmyda O et al. Neurology 2009;73:e92-e93

INC See-saw nystagmus

Torsional nystagmus

Localizing value of torsional nystagmus in small midbrain lesions NEUROLOGY 2002;59:1956–1964

Dorsal midbrain syndrome

Disturbances of vergence eye movements Convergence retraction nystagmus Pseudo abducens palsy A or V-pattern pseudobobbing Convergence spasm Convergence paralysis Divergence parapysis Lid retraction or Ptosis

Fixation instability (square-wave jerks) Skew deviation

Light near dissociation Limitation of upward eye

movements : saccades, pursuit, VOR, Bell’s phenomenon

Disturbances of downward eye movements

Downward saccade, pursuit impairment

(VOR relatively preserved) Downward gaze preference

(setting sun sign) Downbeating nystagmus

Selective upgaze palsy

Convergence excess- pseudoabducens palsy Convergence-retraction nystagmus

Spasm of convergence

Specificity of “Peering at the Tip of the Nose”

for a Diagnosis of Thalamic Hemorrhage Arch Neurol. 2004;61:417‐422

Oculomotor nucleus lesion

Trochlear nucleus and fasciculus

Isolated trochlear palsy due to midbrain stroke Clinical Neurology and Neurosurgery (2010) 68–71 

DDx. with Skew Deviation

Elevated eye is intorted (extorted in 4^thN palsy) Head tilt toward undermost eye if exist Hypertropia decreased in supine position Comitant, Negative Bielschowski head-tilt test

Oculomotor findings in midbrain