Download Horizontal Gaze Palsy

HARVARD MEDICAL SCHOOL
DEPARTMENT OF NEUROLOGY
MASSACHUSETTS GENERAL HOSPITAL
One and a Half Syndrome
Shirley H. Wray, M.D., Ph.D.
Professor of Neurology, Harvard Medical School
Director, Unit for Neurovisual Disorders
Massachusetts General Hospital
The One-and-a-Half Syndrome
On horizontal gaze there is:
An ipsilateral gaze paresis or palsy
An internuclear ophthalmoplegia (INO) on
contralateral gaze
At rest, the eyes are:
Orthophoric, or, in acute stage
Ipsilateral eye esotropic or
Contralateral eye exotropic (Paralytic
pontine exotropic)
Three possibilities to account for an
ipsilateral horizontal gaze palsy: may be
due to unilateral lesion affecting
The ipsilateral PPRF only
The ipsilateral abducens nucleus alone
Both the ipsilateral PPRF and
abducens nucleus
Abducens Nucleus
All the cells necessary for ipsilateral
horizontal gaze:
Motoneurons whose axons form the sixth
nerve (VIN) to innervate the ipsilateral
lateral rectus muscle
Internuclear neurons which send axons
across the midline to opposite MLF and
ultimately to the medial rectus
motoneurons in the contralateral
oculomotor nucleus (III N).
Pathogenesis of Certain Signs
Ocular Motor
Deficit
Possible Pathophysiologic
Substrate
Ipsilateral adduction
weakness
Interruption of axons of abducens
internuclear motoneurons
Ipsilateral slowed
abducting saccades
Inadequate inhibition of medial
rectus motoneurons
Contralateral abduction
nystagmus
Impaired inhibition of contralateral
medial rectus or
Interruption of descending fibers
to contralateral abducens nucleus
or
Involvement of adjacent PPRF
Neurology 1983; 33:971-980
Reported
cases
Brainstem Infarct
12
Multiple Sclerosis
2
Pontine Glioma
2
Arteriovenous Malformation 1
Pontine Hemorrhage
8
Basilar Artery Aneurysm
0
Cerebellar Astrocytoma
2
Metastatic Melanoma
1
Ependymoma Fourth Ventricle 1
29
Table 1. The one-and-a-half syndrome: Etiology
Boston
series
4
14
1
0
0
1
0
0
0
20
Total
16
16
3
1
8
1
2
1
1
49
Diplopia
12
Blurred Vision
8
Oscillopsia
4
Difficulty looking to one side
2
“Quivering” of the eye
1
No visual complaint
3
Table 2. One-and-a-half syndrome (N = 20): Visual Symptoms
(N = 20)
Gaze-evoked upbeat nystagmus
12
Skew deviation
8
Horizontal ipsilateral gaze nystagmus
4
Rotary component to horizontal ipsilateral gaze nystagmus
2
Spontaneous nystagmus to the contralateral side
1
Absent or impaired convergence
5
Saccadic vertical pursuit
9
Gaze-evoked downbeat nystagmus
4
Impaired upward gaze
1
(N = 11)
Exotropia
4
Esotropia
3
Orthotropia
4
Table 3. One-and-a-half syndrome (N = 20;11): Associated ocular motility signs
Cranial Nerve Involvement
I
0
II
1
III
0
V
3
VII
4
VIII
2
IX
3
XI
0
XII
2
Horner’s Syndrome
1
Weakness or spasticity
6
Sensory deficits
7
Abnormally brisk or asymmetric reflexes
5
Extensor plantar responses
9
Incoordination
10
Table 4. One-and-a-half
syndrome (N = 20):
Associated neurologic signs
Esotropia of the
ipsilateral eye
Patient 1. The one-and-a-half syndrome (A) Mild left INO looking right. (B) Esotropia
OS (ipsilateral) in the primary position of gaze. (C) Horizontal conjugate gaze palsy
attempting to look left. (D) Normal convergence.
Paralytic Pontine
Exotropia
Patient 2. Paralytic pontine exotropia. (A) Horizontal conjugate gaze paresis
looking right. (B) Exotropia OS (contralateral) in the primary position of gaze. (C)
Right INO looking left. (D) Right “peripheral-type” ipsilateral facial palsy. (E)
Impaired convergence.
Patient 2. Paralytic Pontine Exotropia
A. Horizontal conjugate palsy looking right.
B. Exotropia OS contralateral in the primary
position of gaze.
C. Right INO looking left
D. Right “peripheral-type” ipsilateral facial
palsy
E. Impaired convergence
In paralytic pontine exotropia the exotropic
eye shows:
Abduction nystagmus during attempts
to move it laterally
Extreme slowness of adduction
saccades when eye fixing to move it to
the midline
Paralytic Pontine Exotropia attributed to:
Tonic contralateral deviation of the eyes
Implies acute ipsilateral PPRF lesion
Failure of ipsilateral eye to deviate
medially explained by the INO
Paralytic pontine exotropia OS
Paralytic pontine exotropia
right horizontal gaze palsy
http://www.library.med.utah.edu/NOVEL