Pearls &amp; Oy-sters: The medial longitudinal fasciculus in ocular motor physiology

Frohman, Teresa C.; Galetta, Steven; Fox, Robert J.; Solomon, David; Straumann, Dominik; Filippi, Massimo; Zee, David S.; Frohman, Elliot M.

doi:10.1212/01.wnl.0000310640.37810.b3

Cited by 84 publications

(62 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The pathogenesis of INO is well understood (figure 1). [4][5][6] Burst neurons lying in the paramedian pontine reticular formation generate a pulse of innervation that projects to 2 populations of neurons in the abducens nucleus: abducens motor neurons and abducens internuclear neurons. The pulse of innervation passes on axons of abducens motoneurons to the lateral rectus muscle, and the eye accelerates to high speeds.…”

Section: Discussionmentioning

confidence: 99%

Using fast eye movements to study fatigue in multiple sclerosis

Matta¹,

Leigh²,

Pugliatti³

et al. 2009

Neurology

View full text Add to dashboard Cite

Objective: To investigate whether internuclear ophthalmoparesis (INO) due to demyelination of the medial longitudinal fasciculus (MLF) provides a model for studying the poorly understood symptom of fatigue in multiple sclerosis (MS). We asked whether repetitive horizontal saccades increased eye movement disconjugacy in patients with MS with INO, but not in healthy subjects. Methods:We compared conjugacy of horizontal saccades in 9 patients with INO (4 bilateral, total 13) and 8 controls during minute 1 and minute 10 of a fatigue test; we measured the ratio of abducting/adducting peak velocity (versional disconjugacy index [VDI]).Results: VDI values were greater in patients than controls. During the fatigue test, controls showed no changes of VDI, but patients did (p Ͻ 0.005) for 10/13 INOs, with increased ratios in 5 cases and a decrease in the other 5. Conclusion:Fatigue-induced worsening of conjugacy was observed in milder internuclear ophthalmoparesis (INO), and may reflect deteriorated fidelity of saccadic pulse transmission along demyelinated medial longitudinal fasciculus. Improved conjugacy was observed in the more severe INOs, and may be due to adaptive mechanisms, such as recruitment of vergence to aid gaze shifts. INO may provide an accessible, reductionist model to study how decreased neural transmission influences fatigue in multiple sclerosis, how the brain adapts to it, and whether drugs may prove therapeutic. Neurology Fatigue is a disabling symptom of MS but its pathogenesis is not understood.1,2 Internuclear ophthalmoparesis (INO) is common in multiple sclerosis (MS), being evident when patients make rapid gaze shifts (saccades) between 2 horizontally separated targets.3,4 Normal subjects show conjugate horizontal saccades but, in INO, the saccade made by the adducting eye is slowed more than the abducting eye ("adduction lag"). The pathogenesis of INO is well understood (figure 1). [4][5][6] Burst neurons lying in the paramedian pontine reticular formation generate a pulse of innervation that projects to 2 populations of neurons in the abducens nucleus: abducens motor neurons and abducens internuclear neurons. The pulse of innervation passes on axons of abducens motoneurons to the lateral rectus muscle, and the eye accelerates to high speeds. 7,8 Abducens internuclear neurons convey the pulse of innervation, via the medial longitudinal fasciculus (MLF), to medial rectus motoneurons in the contralateral oculomotor nucleus that cause the medial rectus muscle to contract rapidly. In normal subjects, the eyes turn rapidly together, as a conjugate saccade. The initial portion of horizontal saccades, which corresponds to the saccadic pulse, is machine-like and normal limits can be defined for the speed of abducting and the adducting eyes.4,7 INO in MS is due to demyelination of the MLF, which causes slowing of the adducting eye, which can no longer conduct high-frequency From Clinical Neurology (M.M., M.P., I.A., A.S.),

show abstract

Section: Discussionmentioning

confidence: 99%

Using fast eye movements to study fatigue in multiple sclerosis

Matta¹,

Leigh²,

Pugliatti³

et al. 2009

Neurology

View full text Add to dashboard Cite

show abstract

“…MLF are the longitudinal nerve fibers that locate on the back of the pons and are close to the front of the fourth ventricle, a part of which relating to horizontal gaze is from the side of the abducens nucleus to the contralateral oculomotor subnucleus (9). The lesion of unilateral pontine tegmentum can damage the ipsilateral MLF, causing the ipsilateral INO, and its clinical manifestations show the ipsilateral intraocular muscle paralysis and contralateral horizontal nystagmus when staring at the opposite side.…”

Section: The Brain Structures and Functions Involving Horizontal Movementioning

confidence: 99%

One-and-a-half syndrome with its spectrum disorders

Xue¹,

Zhang²,

Zhang³

et al. 2017

Quant. Imaging Med. Surg.

View full text Add to dashboard Cite

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). On the basis of the one-and-a-half syndrome, there are a series of related rare syndromes called the one-and-a-half syndrome spectrum disorders. This article reviews rare cases of one-and-a-half syndrome spectrum disorder, describes the clinical and pathological features of different syndromes, and summarizes their nomenclature. Quant Imaging Med Surg 2017;7(6):691-697 qims.amegroups.com Xue et al. One-and-a-half syndrome with its spectrum disorders horizontal conjugate movement of eyes. If the isolated side of PPRF is damaged, the eyes could not gaze at the lesion side, presenting the horizontal gaze palsy to the lesion side (6).The abducens nucleus is located in colliculus facialis, which is in the lower part of the pons and the bottom of the fourth ventricle (7). It contains two functionally distinct cell groups: the abducens motoneurons that innervate the lateral rectus muscle; the internuclear neurons which axons cross the midline and ascend via the contralateral MLF to oculomotor subnucleus and control the medial rectus (8). Therefore, the unilateral lesion of the abducens nucleus will also produce ipsilateral horizontal gaze paralysis.MLF are the longitudinal nerve fibers that locate on the back of the pons and are close to the front of the fourth ventricle, a part of which relating to horizontal gaze is from the side of the abducens nucleus to the contralateral oculomotor subnucleus (9). The lesion of unilateral pontine tegmentum can damage the ipsilateral MLF, causing the ipsilateral INO, and its clinical manifestations show the ipsilateral intraocular muscle paralysis and contralateral horizontal nystagmus when staring at the opposite side. If the damage does not involve the midbrain, the convergence reflex is integrated (10). One-and-a-half syndromeThe one-and-a-half syndrome is caused by a lesion of unilateral tegmentum of pons, causing damage to the PPRF (or abducens nucleus) and MLF ( Figure 2). The most common cause of one-and-a-half syndrome was cerebrovascular disease, and usually was brain stem lacunar infarction, followed by the demyelinating etiology (multiple sclerosis), and then the infectious cause including neurocysticercosis and brainstem encephalitis. Other uncommon causes were head trauma, brain stem tumor (primary or metastasis), astrocytomas, etc. (6,11). Therefore, the vast majority of one-and-a-half syndrome companied by other positioning signs is due to the different lesions of brainstem (3). Only a very small number of patients showed isolated one-and-a half syndrome, while the lesions are smaller and localized, such as brainstem cysticercosis, brainstem tuberculosis, brainstem cavernous hemangioma and the local hemorrhagic infarction of brainstem (12-15).We recently diagnosed a ...

show abstract

“…The medial longitudinal fasciculus (MLF) is a periventricular, dorsomedial brainstem tegmentum pathway that yokes the 2 eyes in many types of eye movements. 1,2 Further, T2 lesions localized in the region containing the MLF strongly associate with INO. 3 However, the small diameter of the MLF and lack of contrast between the MLF and the surrounding neural tissue on conventional MRI hinder direct visualization.…”

Section: Injury To a Specific Neural Pathway Detected By Ultra-high-fmentioning

confidence: 96%