Eye movement Abnormalities in Joubert Syndrome
Avery H. Weiss 1,
Dan Doherty 2*,
Melissa Parisi 3,
Dennis Shaw 4,
Ian Glass 2,
and
James O Phillips 5
1 Ophthalmology, Seattle Children's Hospital, Seattle, Washington, United States
2 Genetics and developmental Medicine, Seattle Children's Hospital, Seattle, Washington, United States; Medical Genetics, University of Washington, Seattle, Washington, United States
3 Genetics and Developmental Medicine, Seattle Children's Hospital, Seattle, Washington, United States; Medical Genetics, University of Washington, Seattle, Washington, United States
4 Radiology, Seattle Children's Hospital, Seattle, Washington, United States
5 Ophthalmology, Seattle Children, Seattle, Washington, United States; Otolaryngology, University of Washington, Seattle, Washington, United States
* To whom correspondence should be addressed. E-mail: dan.doherty{at}seattlechildrens.org.
 |
Abstract |
|---|
Purpose. Joubert syndrome is a genetic disorder characterized by hypoplasia of the midline cerebellum and deficiency of crossed connections between neural structures in the brainstem that control eye movements. Our goal was to quantify the eye movement abnormalities which occur in Joubert syndrome.
Methods. We recorded eye movements in response to stationary stimuli and stimuli designed to elicit smooth pursuit, saccades, optokinetic nystagmus (OKN), vestibular-ocular reflex (VOR) and vergence using video-oculography in 10 patients with Joubert syndrome. All patients underwent high resolution magnetic resonance imaging (MRI).
Results. All patients had the highly characteristic molar tooth sign on brain MRI. Six patients had a conjugate pendular (4) or see-saw nystagmus (2); gaze holding was stable in 4 patients. Smooth pursuit gains were 0.28 to 1.19, 0.11 to 0.68 and 0.33 to 0.73 at peak stimulus velocities of 10, 20 and 30 deg/sec in 6 patients; smooth pursuit could not be elicited in 4 patients. Saccade gains in 5 patients ranged from 0.35 to 0.91 and velocities ranged from 60.9 to 259.5 deg/sec. Targeted saccades could not be elicited in 5 patients. Horizontal OKN gain was uniformly reduced across gratings drifted at velocities of 15, 30 and 45 deg/sec. Vestibular ocular reflex gain was 0.8 or higher and phase appropriate in 3 of seven subjects; VOR gain was 0.3 or less and phase was indeterminate in 4 subjects.
Conclusions.The abnormalities of gaze-holding and eye movements are consistent with the distributed abnormalities of midline cerebellum and brainstem regions associated with Joubert syndrome.
Key Words:
eye movements, genetic diseases, congenital nystagmus, Cerebellum, Brain malformation
