One and a Half Syndrome Definition, Symptoms, Causes, Treatment

One and a half syndrome is an eye movement disorder. In this syndrome weakness occurs in both eyes. One eye, either left or right, cannot move laterally at all while other eye can move laterally in only 1 direction I.e. outward or inward. It is described as horizontal gaze palsy in one direction along with internuclear ophthalmoplegia in other eye. It is a rare and unusual syndrome. Usually eye ball of the eye, which can move laterally, moves away from mid point and other eye cannot move eye ball horizontally at all.

One and a half syndrome occurs due to a single small unilateral lesion in reticular formation of paramedian pontine or occurs as a result of nucleus abducence on one side. This abducence nucleus causes ipsilateral gaze palsy I.e. gaze palsy occurs on the side of lesion. Along with this, the internuclear fibers of ipsilateral medial longitudinal fasciculus are interrupted after crossing midline from its origin. It was all about its pathophysiology. Multiple sclerosis can cause one and a half syndrome. Other than multiple sclerosis, brain stem tumors, Brain stem stroke and malformation in arteries and veins can also cause one and a half syndrome.

One and a Half Syndrome Definition, Symptoms, Causes, Treatment

One and a Half Syndrome Symptoms


One and a half syndrome is related to eye movement disturbances. It is a conjugate of gaze palsy horizontally in one eye and internuclear ophthalmoplegia in other eye. In simple words, one eye can move it's eye ball laterally but in one direction only while other eye cannot move it's eye ball laterally. Some vertical oculomotor symptoms appear which involve vertical nystagmus, ocular bobbing and skew deviation. It does not affect vision I.e. patient can see every thing clearly like a normal person but movement of eye ball in both eyes is not under control.

One and a Half Syndrome Causes


It is an eye movement disorder which occurs as a result of small single lesion in paramedian pontine reticular formation. It is an ipsilateral gaze palsy I.e. it occurs on the same side of lesion. It may be secondary to various diseases I.e. ischemia, tuberculomas ( lesion occurs in tuberculosis infective mass ), hemorrhage in paramedian pontine can lead to one and a half syndrome. Multiple sclerosis is the common cause in which demyelination leads to this syndrome. Other than these, cancer tumors and accidental injuries can also cause one and a half syndrome.

One and a Half Syndrome Treatment


There are no of success stories of botulinum toxin injection in treating one and a  half syndrome and extra ocular movement disorder. Botulinum toxin or Botox is a toxin which is produced by clostridium botulinum. It is responsible for controlling acetylcholine release from axon endings. According to the cause of one and a half syndrome, its treatment is designed. Some helping medications are prescribed like anti platelets (to make blood thin and to make circulation easy), atorvastatin calcium (it resist atherosclerosis) and butylphthalide to improve collateral circulation Because both eyes are involved.
One and a Half Syndrome Definition, Symptoms, Causes, Treatment One and a Half Syndrome Definition, Symptoms, Causes, Treatment Reviewed by Simon Albert on June 16, 2019 Rating: 5
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