Pupillary Abnormalities & INO In Multiple Sclerosis

In Multiple Sclerosis (MS), Nystagmus or InterNuclear Ophthalmoplegia (INO) are the usual Ocular Motor Dysfunctions.

However, in patients with focal BrainStem lesions, other rare manifestations may be observed, such as an Isolated Ocular Motor Nerve Palsy or Complex Ocular Motor Disturbances.

We report five MS patients with unusual Ocular Motor Disturbances (BiLateral Third Nerve Palsy [n = 2], OpsoClonus, Horner's Syndrome and One-And-A-Half Syndrome).

We discuss possible correlations between clinical disturbances and MRI abnormalities.

Patients were seen in two MS centers. They had a confirmed diagnosis of MS and underwent a Brain MRI and a complete Neuro-Ophthalmological work-up.

In one case (OpsoClonus), Ocular Motor manifestations were the first manifestation of MS.

In the other four cases they occurred 3 months (Horner syndrome), 6 years and 12 years (BiLateral Third Nerve Palsy) and 2 years (One-And-A-Half Syndrome) after the disease onset, respectively.

Four out of five patients were still in a Relapsing/Remitting form of MS.

In the OpsoClonus case, there was no evidence of a BrainStem lesion. A gadolinium-enhanced lesion (2 cases) or a new T2-weighted lesion located in the BrainStem correlated with the clinical presentation.

All patients completely or partially recovered after CorticoSteroid infusions. Our study shows some rare or previously undescribed Complex Ocular Motor Symptoms in MS.

InterNuclear Ophthalmoplegia (INO) is a distinctive ocular motor disorder resulting from dysfunction of the Medial Longitudinal Fasciculus, which lies in the Pontine Tegmentum.

We retrospectively analyzed clinical and Magnetic Resonance Imaging (MRI) findings for four consecutive patients with InterNuclear Ophthalmoplegia who were treated in our hospital.

The causes of the disease were Cerebral Infarction in three cases and Multiple Sclerosis in one case. Vertigo and Facial Nerve Palsy were associated in three cases and one case, respectively.

MRI studies visualized an Ischemic lesion in the responsible portion of the BrainStem in one patient but failed to reveal responsible lesions in the other three patients.

All the patients completely recovered in 1 to 22 days, with an average recovery period of 9.3 days. The etiology, diagnosis and management of INO were bibliographically reviewed.

Eye movements serve vision, which has two different aims: changing images using Saccades, i.e. rapid eye movements, and stabilizing new images on the Retina using slow eye movements.

Eye movements are performed by Ocular Motor Nuclei in the BrainStem, on which SupraNuclear pathways - originating in the Cerebral Cortex, Cerebellum and Vestibular structures - converge.

It is useful for the Neurologist to know the clinical abnormalities of eye movements visible at the bedside since such signs are helpful for localization.

Eye movement paralysis may be Nuclear or Infranuclear (Nerves), involving all types of eye movements, i.e. Saccades as well as the Vestibulo-Ocular Reflex (VOR), or SupraNuclear, in which case the VOR is usually preserved.

Lateral eye movements are organized in the Pons, with paralysis of adduction (and preservation of Convergence) when the lesion affects the Medial Longitudinal Fasciculus (InterNuclear Ophthalmoplegia).

Paralysis of conjugate lateral eye movements when the lesion affects the Abducens Nucleus (VI) and the "One-And-A-Half" Syndrome when both these structures are involved.

Vertical eye movements are organized in the MidBrain, with Ipsilateral Oculomotor (III) paralysis and ContraLateral Paralysis of the Superior Rectus Muscle when the Third Nerve Nucleus is unilaterally damaged.

SupraNuclear Upward Gaze Paralysis when the Posterior Commissure is UniLaterally damaged and SupraNuclear Downward Gaze Paralysis (often coupled with Upward Gaze Paralysis) when the Mesencephalic Reticular Formations are BiLaterally damaged.

Numerous types of abnormal eye movements exist, of which Nystagmus is the most frequent and usually due to damage to peripheral or Central Vestibular Pathways.

Cerebral Hemispheric or Cerebellar damage results in subtle eye movement abnormalities at the bedside, in general only detected using eye movement recordings.

Because of the multiplicity of eye movement pathways at these levels and their reciprocal compensation in the case of a lesion. Lastly, eye movements can also help the NeuroScientist to understand the organization of the Brain.

They are a good model of Motricity allowing us, using eye movement recordings, to study the Afferent Pathways of the Cortical Areas that trigger them.

And, thus to analyze relatively complex NeuroPsychological processes such as Visuo-Spatial Integration, Spatial Memory, Motivation and the preparation of Motor Programs.

Background
Some patients with Acquired Horizontal Gaze Palsy overcome the Adduction Palsy by utilizing convergence.

This substitution phenomenon is very rare. We report a patient with Horizontal Gaze Palsy who was able to use convergence to compensate for the lack of adduction in the left eye.

Case
The patient was a 31-year-old woman with an ArterioVenous Malformation in the Fourth Ventricle.

She suffered Right Gaze Palsy and Right Abducens Palsy after tumor surgery and radiation therapy.

Observations
Three years after the Vascular accident, she was found to be able to adduct the left eye, in association with the adduction of the right eye.

At the same time, constriction of both pupils and globe retraction of the left eye were observed.

When she shifted the gaze direction of her left eye from left to right, an 11 and 8 diopter increase of Myopia in the right and left eyes, respectively, was confirmed by objective Refractometry.

Conclusions
The existence of convergence substituting for adduction in this patient with Horizontal Gaze Palsy was confirmed by refraction change in addition to Pupillary change.

Objective
The authors imaged the Medial Longitudinal Fasciculus (MLF) in 58 patients with MS and chronic InterNuclear Ophthalmoparesis (INO) to determine which MRI technique best shows the characteristic lesion associated with this Ocular Motor Syndrome.

Methods
Using quantitative infrared Oculography, the authors determined the ratios of Abduction to Adduction for Velocity and Acceleration.

To confirm the presence of INO and to determine the severity of MLF dysfunction in 58 patients with MS and INO.

Conventional MRI techniques, including Proton Density Imaging (PDI), T₂-weighted imaging, and Fluid-Attenuated Inversion Recovery (FLAIR) imaging, were used to ascertain which technique best shows MLF lesions within the BrainStem Tegmentum.

T₁-weighted imaging was performed to determine the frequency of BrainStem Tegmentum HypoIntensities.

Results
All patients studied had evidence of an MLF lesion HyperIntensity on PDI, whereas T₂-weighted imaging and FLAIR imaging showed these lesions in 88% and 48% of patients, respectively.

With PDI, DorsoMedial Tegmentum lesions were seen in the Pons in 93% of patients and in the MidBrain of 66% of patients.

Lesions were observed at both locations in 59% of patients. One patient had an MLF lesion with a corresponding T₁ HypoIntensity.

Conclusions
PDI best shows the MLF lesion in patients with MS and INO.

Objectives
To develop a hypothetical scheme to account for clinical disorders of Vertical Gaze based on recent insights gained from experimental studies.

Methods
The authors critically reviewed reports of anatomy, physiology, and effects of pharmacologic inactivation of MidBrain Nuclei.

Results
Vertical Saccades are generated by burst Neurons lying in the rostral interstitial Nucleus of the Medial Longitudinal Fasciculus (riMLF).

Each burst Neuron projects to MotoNeurons in a manner such that the eyes are tightly coordinated (yoked) during Vertical Saccades.

Saccadic innervation from right MLF is unilateral to depressor muscles but BiLateral to elevator muscles, with Axons crossing within the Oculomotor Nucleus.

Thus, right MLF lesions cause Conjugate Saccadic Palsies that are usually either complete or selectively downward. Each right MLF contains burst Neurons for both up and down Saccades, but only for Ipsilateral Torsional Saccades.

Therefore, unilateral right MLF lesions can be detected at the bedside if torsional quick phases are absent during IpsiDirectional head rotations in roll.

The Interstitial Nucleus of Cajal (INC) is important for holding the eye in Eccentric Gaze after a Vertical Saccade and coordinating eye-head movements in roll.

BiLateral INC lesions limit the range of Vertical Gaze. The Posterior Commissure (PC) is the route by which INC projects to Ocular MotoNeurons.

Inactivation of PC causes Vertical Gaze-Evoked Nystagmus, but destructive lesions cause a more profound defect of Vertical Gaze, probably due to involvement of the Nucleus of the PC.

Vestibular signals originating from each of the Vertical Labyrinthine Canals ascend to the MidBrain through several distinct pathways.

Normal Vestibular function is best tested by rotating the patient's head in the planes of these canals.

Conclusions
Predictions of a current scheme to account for Vertical Gaze Palsy can be tested at the bedside with systematic examination of each functional class of eye movements.

How the human Brain controls the subtle coupling between eye and head movements is still debated. The Brain could either coordinate two separate (eye and head) networks or use a single system involved in gaze (eye + head) control.

In a recent report, a total transfer from eye to head movements was observed in a patient with Congenital Ophthalmoplegia. This led the authors to hypothesize that such transfer resulted from a long-term adaptation between Oculomotor and head movement systems.

We report on a patient in whom a similar transfer was observed but at the acute stage of an acquired Ophthalmoplegia.

This case demonstrates that the transfer between head and eye movements does not necessarily require long-term adaptation and supports the hypothesis of a common unique Gaze Motor Command in which eye and head movements would be rapidly exchangeable.

Background
Isolated Down-Gaze Palsy is the least common pathology of Vertical Gaze.

Patients with Low-Gaze Palsy may consult an Ophthalmologist with difficulty in reading and this may be the only Ocular finding of a Central Nervous System lesion.

Methods
A 43-year-old man with Isolated Down-Gaze Palsy was examined. The medical history of the patient revealed that he had had Myocardial Infarction.

Result
Magnetic Resonance Imaging disclosed an Ischemic area at the Right Thalamus.

Conclusion
Down-Gaze Palsy may be an important sign for the diagnosis of Thalamic Infarctions due to Embolic Syndrome.