The PPRF is the premotor structure of all ipsilateral saccades (including quick phases of nystagmus) and the generator of horizontal saccadic pulse. From: Handbook of Clinical Neurology, 2011.
What is the function of PPRF?
The paramedian pontine reticular formation, also known as PPRF or paraabducens nucleus, is part of the pontine reticular formation, a brain region without clearly defined borders in the center of the pons. It is involved in the coordination of eye movements, particularly horizontal gaze and saccades .
Where is the horizontal gaze center located?
The PPRF is located on the medial aspect of the pontine reticular formation about 2 mm from the midline . The PPRF receives input through polysynaptic connections from the vestibular nuclei and contralateral frontal lobe for saccades.
What is eight and a half syndrome?
Eight-and-a-half syndrome describes a constellation of symptoms that occur due a lesion involving the abducens (cranial nerve (CN) VI) nucleus, the fascicular portion of the facial (CN VII) nerve, and the medial longitudinal fasciculus (MLF).
What is one and a half syndrome?
One-and-a-half syndrome is a syndrome characterized by horizontal movement disorders of the eyeballs , which was first reported and named by Fisher in 1967. It presents a combination of ipsilateral conjugate horizontal gaze palsy (one) and ipsilateral internuclear ophthalmoplegia (INO) (a half).
What part of the brain controls Saccades?
The parietal lobe and more particularly its posterior part, the PPC , are involved in the control of saccades and attention.
What is internuclear ophthalmoplegia?
Internuclear ophthalmoparesis (INO), also commonly referred to as internuclear ophthalmoplegia, is a specific gaze abnormality characterized by impaired horizontal eye movements with weak and slow adduction of the affected eye , and abduction nystagmus of the contralateral eye.
Where is the gaze center?
The rostral interstitial nucleus or vertical gaze center is located in the rostral part of the midbrain reticular formation and is responsible for vertical movements. Activation of each gaze center separately results in movements of the eyes along a single axis, either horizontal or vertical.
What causes parinaud syndrome?
Anything that causes unusual swelling or pressure in your brain may cause Parinaud syndrome. The most common causes include: brain tumors in the midbrain region or pineal gland . stroke .
What is conjugate gaze palsy?
A conjugate gaze palsy is inability to move both eyes together in a single horizontal (most commonly) or vertical direction.
What causes one and a half syndrome?
One-and-a-half syndrome is most often caused by multiple sclerosis (MS), brain stem stroke, brain stem tumors, and arteriovenous malformations .
What does skew deviation mean?
Skew deviation is a vertical strabismus caused by supranuclear lesions . It is often associated with ocular torsion and head tilt, which together constitute the ocular tilt reaction. 1 – 4 . Skew deviation is often the initial manifestation of diseases that affect the brainstem, cerebellum, or peripheral vestibular system.
What causes internuclear ophthalmoplegia?
Internuclear ophthalmoplegia (INO) is a disorder of eye movements caused by a lesion in an area of the brain called the medial longitudinal fasciculus (MLF). The most common causes of INO are multiple sclerosis and brainstem infarction .
Are saccadic eye movements normal?
Saccades are the fastest eye movements ( up to about 500 degrees per second ) and they are very brief in duration (typically less then 100 msec) [1]. We will review the anatomy, basic clinical features and examination of normal saccades, and then review movement disorders in which saccadic abnormalities aid in diagnosis.
How can I improve my saccadic eye movement?
Saccadic deficiencies can be treated using vision therapy at any age , and it can help to improve reading speed and ability. Some of the treatments that might be used are monocular exercises done with a patch including charts, games, hitting a Marsden Ball, and doing eye stretches and jumps.
What do saccades indicate?
| Class of eye movement Main function | Saccades Brings images of objects of interest onto the fovea | Vergence Moves the eyes in opposite directions so that images of a single object are placed or held simultaneously on the fovea of each eye |
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