Conjugate Gaze Palsies: Understanding Eye Movement Disorders

The ability of our eyes to move together and in harmony to the right, left, or upward depends not only on the muscles but also on the flawless functioning of the brain's complex control mechanisms. Conjugate gaze palsy is a neurological eye movement disorder in which this coordination is disrupted, and both eyes cannot move together in a specific direction. If you would like to learn more about this condition, please take a look at our content.

What Is the Conjugate Gaze Palsies

Conjugate gaze palsy is an important neurological finding characterized by the inability of both eyes to move synchronously in the same direction, and it usually develops due to damage to the gaze centers in the brainstem. Under normal conditions, looking to the right or left is achieved through signals originating in cortical centers and coordinated via the paramedian pontine reticular formation (PPRF), the sixth nerve nucleus, and the medial longitudinal fasciculus (MLF) in the brainstem. Thus, a lesion at any point in this network can disrupt the coordinated movement of the eyes. Clinically, the patient may be unable to look in a specific direction, the eyes may remain fixed in the midline, and additional neurological findings such as double vision (diplopia), balance disorders, or accompanying facial paralysis may frequently be observed. In this context, the most common cause is brainstem stroke, but demyelinating diseases (e.g., multiple sclerosis), tumors, trauma, and, rarely, neurodegenerative conditions can also lead to this condition. Consequently, treatment is directed at the underlying cause, and the prognosis varies depending on the extent of the damage and the type of pathology.

Types of Gaze Palsies

There are specific types of gaze palsy. These types are determined based on the form of eye palsy. In this context, gaze palsy is divided into four types. These are: Horizontal Gaze Palsy, Vertical Gaze Palsy, Internuclear Ophthalmoplegia, and One-and-a-Half Syndrome. If we examine these types in detail;

• Horizontal Gaze Palsy:

Horizontal gaze palsy is characterized by the inability of the eyes to move together to the right or left and usually develops due to damage to the gaze centers at the pons level. In this type of gaze palsy, the eyes cannot turn to the desired side, and the patient may try to look by turning their head. The most common cause in this context is a stroke affecting the brainstem. However, diseases affecting the nerves, such as multiple sclerosis, or tumors can also cause this. Therefore, it requires urgent evaluation when it develops suddenly.

• Vertical Gaze Palsy:

In this type of gaze palsy, the person has difficulty moving their eyes up or down. In particular, an inability to look up is more common. Therefore, the patient may have difficulty climbing stairs, looking at an object above them, or reading a book. Furthermore, this condition usually occurs due to the involvement of the control centers in the middle part of the brain. Therefore, it may develop gradually in some neurological diseases, while in some cases it may appear suddenly.

• Internuclear Ophthalmoplegia:

In another type of gaze palsy called Internuclear Ophthalmoplegia, the eyes have difficulty moving together, but the problem is slightly more specific. Therefore, when the patient wants to look in one direction, one eye may move while the other eye remains in the midline. The most common cause of this type of gaze palsy in young patients is multiple sclerosis; in older patients, it is usually caused by vascular occlusions.

• One-and-a-Half Syndrome:

One-and-a-Half Syndrome, a type of gaze palsy, prevents the patient from looking in one direction; when looking in the other direction, only one eye moves. In other words, horizontal eye movement is almost completely impaired. This condition stems from a small but significant lesion in the brainstem. Therefore, it requires a neurological evaluation.

Causes of Conjugate Gaze Palsy

Conjugate gaze palsy is the loss of the ability of both eyes to look in the same direction (horizontal or vertical) at the same time. This condition usually stems not from the eye muscles themselves, but from damage to the gaze centers in the brain or the nerve pathways connecting these centers. At this point, the causes of gaze palsy are as follows:

1. Vascular Causes: Blood flow disorders in the brain stem and cerebral cortex are among the most common causes.

• Stroke: Ischemic or hemorrhagic strokes affecting the frontal gaze center or pathways in the brain stem.
• Vasculitis: Impaired nourishment of nerve pathways due to inflammation of the brain vessels.

2. Tumor Causes: Masses that exert pressure on strategic areas of the brain impair visual control.

• Brain Stem Tumors: Lesions in the pons region in particular cause horizontal gaze palsy.
• Pineal Region Tumors: Pressure on the upper part of the brain can lead to Parinaud Syndrome, characterized by upward gaze palsy.

3. Neurodegenerative Diseases: The gradual destruction of nerve cells affects visual mechanisms.

• Progressive Supranuclear Palsy (PSP): It is one of the most typical causes of vertical (up/down) gaze palsy.
• Parkinson's Disease: In advanced stages, restricted eye movements may be observed.
• Demyelinating Diseases: Damage to the sheaths that enable nerve transmission disrupts coordination.

4. Multiple Sclerosis (MS): It is the most common cause of a condition called Intranuclear Ophthalmoplegia (INO), which impairs the coordinated movement of the eyes.

5. Infections and Inflammation

• Encephalitis: Inflammation of brain tissue.
• Wernicke's Encephalopathy: A clinical condition that usually develops due to vitamin B1 (thiamine) deficiency and affects eye movements.
• Meningitis: Inflammation of the brain membrane affecting the cranial nerves.

6. Trauma and Other Causes

• Head Injuries: Shearing injuries to the brain stem (diffuse axonal injury).
• Metabolic Disorders: Severe liver failure or certain drug poisonings.
• Congenital (Birth) Causes: Rare developmental disorders such as Möbius syndrome.

Conjugate Gaze Palsies Diagnosis

The diagnosis of conjugate gaze palsy begins with a detailed neurological examination and focuses on determining the location of the lesion within the central nervous system. In this context, during the clinical evaluation, the patient is asked to look to the right and left; it is observed whether both eyes move together and symmetrically. If horizontal gaze restriction is detected after this observation, involvement at the pons level, particularly of the paramedian pontine reticular formation (PPRF) or abducens nucleus, is considered; while deviation of the eyes toward the lesion side may suggest supranuclear pathologies originating in the frontal eye field (FEF). Differential diagnosis should exclude internuclear ophthalmoplegia, isolated cranial nerve palsies, and neurodegenerative conditions such as progressive supranuclear palsy.

Following clinical findings, magnetic resonance imaging (MRI) is used to evaluate the brainstem and cortical areas in detail; diffusion-weighted MRI is critical for detecting stroke foci in acute cases. When necessary, computed tomography, vascular imaging (MR angiography/CT angiography), and laboratory tests are also added. Thus, the diagnosis of conjugate gaze palsy is made not only by looking at eye movement but also by evaluating neuroanatomy knowledge, clinical correlation, and advanced imaging methods together.

Treatment Methods for Conjugate Gaze Palsy

The treatment of conjugate gaze palsy depends on the underlying cause that directly leads to this condition (stroke, tumor, MS, etc.). Since there is no problem with the eye muscles themselves, treatment is generally neurologically focused. The treatments applied in this context are as follows:

• Stroke and Vascular Problems: If the cause is a blocked blood vessel, blood thinners or blood pressure medications are used. Once the blood vessel is opened, nerve function may gradually return.
• Tumors: Masses such as skull base chordomas or brain stem tumors are reduced by surgical resection, radiotherapy (especially Proton Therapy), or chemotherapy to relieve pressure on the nerves.
• Multiple Sclerosis (MS): During attack periods, high-dose steroid (cortisone) treatment suppresses inflammation in the nerve sheath, aiming to improve visual function.
• Infections: Appropriate antibiotic or antiviral treatments are administered in cases of meningitis or encephalitis.
• Vitamin Supplements: Especially in cases of Wernicke's Encephalopathy caused by B1 (Thiamine) deficiency, emergency vitamin loading can rapidly reverse the paralysis.
• Edema Reducers: Corticosteroids are used to reduce edema in the brain stem.
• Prismatic Glasses: Special prismatic lenses may be prescribed to alleviate double vision (diplopia) and focus images into a single point.
• Eye Patch (Occlusion): If double vision is very bothersome, temporarily covering one eye can prevent the patient's nausea and dizziness.
• Neuro-Ophthalmological Exercises: In some cases, “eye tracking exercises” are performed under specialist supervision to stimulate eye movements and retrain the brain in this function.
• Strabismus Surgery: Surgery can be performed on the eye muscles to correct the eyes and prevent the patient from constantly tilting their head (This only alleviates the symptom; it does not completely cure the paralysis).

If you are suffering from facial paralysis, you can immediately contact Dr. Be's team, who are experts in facial paralysis.