What is the pathophysiology of one and a half syndrome?
Scheme showing anatomical location of lesions in one and a half syndrome. The syndrome usually results from single unilateral lesion of the paramedian pontine reticular formation and the ipsilateral medial longitudinal fasciculus.
Can multiple sclerosis cause one and a half syndrome?
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 is related to eye movement disturbances.
What are the treatment options for one and a half syndrome?
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.
What is one-and-a-half syndrome?
One-and-a-half syndrome is a disorder of horizontal ocular movement characterized by a lateral gaze palsy on looking toward the side of the lesion and INO on looking in the other direction. The location of the lesion is the paramedian pontine reticular formation or VI nerve nucleus.
Why is it called one and half syndrome?
In this syndrome, patients present with a combination of an ipsilateral conjugate horizontal gaze palsy (referring to the 'one' horizontal gaze palsy) and an ipsilateral internuclear ophthalmoplegia (INO) (referring to the 'half' of a horizontal gaze palsy).
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 halfman syndrome?
More formally, it is characterized by "a conjugate horizontal gaze palsy in one direction and an internuclear ophthalmoplegia in the other". Nystagmus is also present when the eye on the opposite side of the lesion is abducted.
What is vertical gaze palsy?
A vertical gaze palsy (VGP) is a conjugate, bilateral, limitation of the eye movements in upgaze and/or downgaze.
What is Foville syndrome?
Foville syndrome (FS) is an inferior medial pontine stroke syndrome that most commonly presents with contralateral hemiparesis and ipsilateral abducens and facial palsies.
What causes ophthalmoplegia?
What causes ophthalmoplegia? This condition can be congenital (present at birth) or develop later in life. It is generally caused by disruption of the messages that are sent from the brain to the eyes. Internuclear ophthalmoplegia is often caused by multiple sclerosis, trauma, or infarction.
Where is the lesion in one and half syndrome?
One-and-a-half syndrome is a disorder of horizontal ocular movement characterized by a lateral gaze palsy on looking toward the side of the lesion and INO on looking in the other direction. The location of the lesion is the paramedian pontine reticular formation or VI nerve nucleus.
What is the life expectancy of someone with SMA syndrome?
It's sometimes called Werdnig-Hoffmann disease or infantile-onset SMA. Children with type 1 have limited movement, can't sit without support, and have trouble breathing, feeding, and swallowing. Symptoms begin at birth or within the first six months of life. Many children with type 1 do not live past age 2.
What is internuclear ophthalmoplegia?
INTRODUCTION. 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.
What are the 3 types of nystagmus?
Spontaneous central vestibular nystagmusDownbeat nystagmus.Upbeat nystagmus.Torsional nystagmus.
What are the 9 positions of gaze?
The nine gazes are: straight ahead, left, right, straight up, up and to the left, up and to the right, straight down, down and to the left, down and to the right.
What does gaze palsy look like?
Gaze Palsies In one direction, the eyes cannot move reflexly to take up fixation or, more rarely, cannot follow a moving target (pursuit palsy). In lateral gaze palsy, the two eyes will not move beyond the mid-line. In vertical gaze palsy, movements above and/or below the horizontal are restricted.
What is internuclear ophthalmoplegia?
INTRODUCTION. 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.
What is medial longitudinal fasciculus?
The medial longitudinal fasciculus (MLF) is a specialized and heavily myelinated nerve bundle adjacent to the cranial nerve III and IV nuclei in the midbrain. It extends in a craniocaudad dimension to the level of the cranial nerve VI nuclei in the inferior and dorsal pons.
What causes OAHS in the brain?
Demyelinating lesions (s uch as multiple sclerosis) and brainstem malignancies (primary or metastatic) including gliomas, metastatic melanoma, ependymoma of the fourth ventricle and astrocytoma of the cerebellum can also cause OAHS. More rarely, infectious causes including neurocysticercosis, brainstem tuberculomas, ...
How to diagnose OAHs?
The diagnosis of OAHS is made through a combination of clinical and radiological findings. Clinically, a full ocular motility exam, including assessment of convergence, is performed. In addition, a thorough neurological exam with particular attention to the cranial nerves may further assist in lesion localization. Ocular manifestations of myasthenia gravis (MG) can imitate OAHS (i.e., a pseudo-OAHS), but adduction deficits would not be overcome with attempted convergence in MG. In the case of suspected MG or thyroid disease, MG antibody tests or thyroid function tests can be of clinical consideration respectively . Finally, to further elucidate the etiology underlying these symptoms, neuro-imaging is indicated, with MRI being the modality of choice to examine and localize underlying brainstem lesions .
What is OAHS in ophthalmology?
In 1967, Miller Fisher described a pattern of ophthalmoplegia in patients with various pontine lesions , known as “one-and-a-half syndrome” (OAHS). In this syndrome, patients present with a combination of an ipsilateral conjugate horizontal gaze palsy (referring to the ‘one’ horizontal gaze palsy) and an ipsilateral internuclear ophthalmoplegia (INO) (referring to the ‘half’ of a horizontal gaze palsy) .
Which eye is always straight ahead?
The ipsilateral eye usually remains fixed straight ahead but has diminished or no ability to move in right or left horizontal gaze. In some cases, the contralateral eye can be exotropic, with abduction nystagmus during attempts of lateral eye movements . In OAHS vertical gaze is preserved.
How long does it take to recover from OAHS?
Prognosis of OAHS depends on the underlying cause and management, but can sometimes resolve spontaneously with a typical recovery period of a few weeks to months .
Is OAHS a horizontal or vertical gaze palsy?
Since the OAHS is a combination of an ipsilateral horizontal gaze palsy and an ipsilateral INO, understanding of the relevant neuroanatomy and potential lesion locations is critical. Given the pathway described earlier, there seems to be four possible lesion locations to account for the horizontal gaze palsy in the OAHS, including (1) damage to both the ipsilateral abducens nuclei and the PPRF, (2) damage to the ipsilateral abducens nuclei only, (3) damage to the ipsilateral PPRF only, and (4) damage to the ipsilateral abducens nerve root fiber together with the contralateral MLF in the event of two separate lesions .
What is one and a half syndrome?
One-and-a-half syndrome is a disorder of horizontal ocular movement characterized by a lateral gaze palsy on looking toward the side of the lesion and INO on looking in the other direction. The location of the lesion is the paramedian pontine reticular formation or VI nerve nucleus. MLF fibers crossing from the contralateral VI nucleus are also involved, causing INO. The common causes of this syndrome are similar to those of INO (e.g., multiple sclerosis, stroke). Hemorrhage or tumor in the lower pons is also in the differential diagnosis. Pseudo–one-and-a-half syndromes may occur with myasthenia gravis, Wernicke's encephalopathy, or Guillain-Barré syndrome. Clinical signs include the following:
What is the right paramedian pontine syndrome?
Right paramedian pontine syndrome. The eyes display a left exotropia in primary position. In right gaze, neither eye crosses the midline. In left gaze, the right eye does not cross the midline and the left eye has a normal excursion.
What are the symptoms of ipsilateral eye palsy?
Clinical signs include the following: 1. Horizontal gaze palsy on looking toward the size of the lesion (“one”). 2. INO on looking away from the side of the lesion (“half”). This paralyzes adduction and causes nystagmus on abduction. As a result, the ipsilateral eye has no horizontal movement, and the only lateral ocular movement ...
Where do hematomas originate?
Lateral tegmental brainstem hematomas usually originate from vessels penetrating into the brainstem from long circumferential branches. They enter the tegmentum laterally and course medially. Small hematomas remain confined to the lateral tegmentum, and larger lesions spread across to the opposite side and can destroy the entire tegmentum. Neurologic examination reveals a predominantly unilateral tegmental lesion with variable degrees of basilar involvement. 191,192 Oculomotor abnormalities, especially the “one-and-a-half syndrome,” horizontal gaze palsy, internuclear ophthalmoplegia, partial involvement of vertical eye movements, and ocular bobbing, have been described. 191,192,571,577–579 The tegmental location of the spinothalamic tract makes sensory symptoms common. Ataxia, either unilateral or bilateral, may also accompany the oculomotor signs. 191,192 Action tremor has developed as the transient hemiparesis improves; this observation can be possibly explained by involvement of the red nucleus or its connections. 192 Facial numbness, ipsilateral miosis, and hemiparesis have also been noted. 191,192 Two patients 191 developed Cheyne-Stokes respirations, one of the short-cycle type, 415,532 the other of the classic variety. Table 28-11 reviews some reported examples of tegmental pontine hematomas. 137,191,192,534,558,566,578
Is one and half rare?
The “one-and-a-half” syndrome is not really rare since it may result from relatively small unilateral dorsal tegmental pontine lesions but also from much larger unilateral pontine lesions. It may be due to brainstem ischemia, multiple sclerosis, tumor, hemorrhage, trauma, or infection ( Leigh and Zee, 2006 ).
Does a pontine hemorrhage cause dizziness?
We examined two patients with tegmental pontine hemorrhage , and Lawrence and Lightfoote 580 studied a patient with a pontine AVM; all three patients showed vertical pendular ocular oscillations with dizziness and vertical oscillopsia weeks after the hemorrhage. Delayed pain in the contralateral limbs, as in the thalamic pain syndrome, began during recovery from a unilateral tegmental hemorrhage in another patient. We have also observed “palatal myoclonus” as a sequela of lateral tegmental hematomas.
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.
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.
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.
Disease
- In 1967, Miller Fisher described a pattern of ophthalmoplegia in patients with various pontine lesions, known as “one-and-a-half syndrome” (OAHS). In this syndrome, patients present with a combination of an ipsilateral conjugate horizontal gaze palsy (referring to the ‘one’ horizontal gaze palsy) and an ipsilateral internuclear ophthalmoplegia (INO...
Etiology
- Any disease causing a pontine lesion can account for the findings seen in the OAHS, including vascular, inflammatory, traumatic, infiltrative, demyelinating and neoplastic. Of these, the most commonly reported etiology in adults is vascular, including mainly ischemic brainstem infarction, pontine hemorrhages, basilar artery aneurysms and arteriovenous malformations . Demyelinatin…
Clinical Presentation
- OAHS presents with an ipsilateral conjugate horizontal gaze palsy and limited adduction of the ipsilateral eye (INO). The ipsilateral eye usually remains fixed straight ahead but has diminished or no ability to move in right or left horizontal gaze. In some cases, the contralateral eye can be exotropic, with abduction nystagmus during attempts of lateral eye movements . In OAHS vertic…
Physiology
- In discussing horizontal eye movements, there are three main structures within the dorsal pontine tegmentum that are relevant, namely the Paramedian Pontine Reticular Formation (PPRF), the internuclear fibers of the Medial Longitudinal Fasciculus (MLF) and the abducens nuclei . The PPRF and the abducens nuclei act as the final pre-nuclear and nuclear centers for horizontal ey…
Pathophysiology
- Since the OAHS is a combination of an ipsilateral horizontal gaze palsy and an ipsilateral INO, understanding of the relevant neuroanatomy and potential lesion locations is critical. Given the pathway described earlier, there seems to be four possible lesion locations to account for the horizontal gaze palsy in the OAHS, including (1) damage to both the ipsilateral abducens nuclei …