The control of eye movements is complex and involves muscles, nerves, and interconnecting pathways. Three pairs of muscles, known as the extraocular muscles, are involved in the movement of each eye: the superior and inferior oblique, superior and inferior recti, and lateral and medial recti. The extraocular muscles are responsible for three types of eye movement: horizontal (the pupil directed toward or away from the nose), vertical (the pupil directed up or down), and torsional (rotational movement of the eyes). The three nerves that originate from the brain stem *
What Are the Symptoms of Ophthalmoplegic Syndromes?
The most common symptom is diplopia (de-PLO-pee-ah), or double vision * . Diplopia can involve one or both eyes, can be painful or painless, can come on suddenly or gradually, and can be congenital (present at birth) or acquired. Other symptoms, depending on the type of opthalmoplegic syndrome encountered, include blurred vision, a drooping of the eyelids, difficulty controlling eye movement, a general weakness of the skeletal muscles, and difficulty swallowing.
What Are Some of the Common Ophthalmoplegic Syndromes and Their Causes?
Congenital ophthalmoplegiaCongenital ophthalmoplegia is a rare nonprogressive syndrome due to fibrosis (increased fibrous tissue) of one or several of the muscles supplied by the third nerve, leading to restriction of upward gaze.
Acquired ophthalmoplegic syndromes can be classified by the part of the eye movement control apparatus that is involved.
In Graves’ disease, in which there is too much functioning of the thyroid gland * , the extraocular muscles become bulky due to fat and connective tissue * deposits leading to a “staring look” with restriction of eye movements. Orbital fractures, direct trauma * to the eye, or tumors * may lead to muscle entrapment and ophthalmoplegia.
Progressive external ophthalmoplegia develops in late childhood or adolescence with paralysis of the extraocular muscles, ptosis (droopy eyelids), hearing loss, cataracts * , neuropathy, ataxia (lack of coordination), and sexual dysfunction.
Kearns-Sayre syndrome starts in the first or second decade with ophthalmoplegia, retinal degeneration, ataxia, deafness, muscle weakness (face and swallowing), and heart rhythm abnormalities. These disorders are due to DNA mutation and are either inherited or occur sporadically.
The typical disorder is myasthenia gravis (MY-as-theen-a GRAV-us), which is characterized by ptosis and extraocular, skeletal, and respiratory * muscle weakness that typically worsens with activity and improves with rest. It occurs at any age from childhood to adulthood and is due to an immune * attack on acetylcholine (a chemical involved in neuromuscular transmission) receptors * .
Another disorder is botulism, in which the botulinum toxin from certain bacteria leads to pupil dilatation and ophthalmoplegia.
A tumor, aneurysm, or clot located behind the eye can lead to painful, puffy, and paralyzed eyes. Tolosa-Hunt syndrome is an inflammatory condition of the same region that causes painful ophthalmoplegia. Various infections or infiltration of cancer cells can affect the cranial nerves, resulting in ophthalmoplegia. In the brainstem, strokes * , tumors, and multiple sclerosis * can all result in this condition.
Ophthalmoplegic migraine is a type of headache that causes transient paralysis of the extraocular muscles. In diabetes * , due to interruption of blood supply, painful paralysis of one or more muscles supplied by that cranial nerve occurs.
In internuclear ophthalmoplegia, the MLF is affected by multiple sclerosis, tumor, or stroke, leading to a disturbance in conjugate (paired or parallel) eye movements.
Progressive supranuclear palsy is a rare neurodegenerative disorder affecting certain parts of the brain that exert control over the nuclei involved in eye movement, resulting in restricted upgaze, gait imbalance, dementia * , and symptoms similar to Parkinson's disease * . Neurodegenerative diseases such as Huntington disease * , Wilson's disease (due to impaired copper metabolism), and Wernicke's disease (due to thiamine deficiency from chronic alcohol use) impair the upward gaze.
Injury to various parts of the cerebral cortex * due to tumors, strokes, and trauma may result in ophthalmoplegia.
Antipsychotic drugs (medications used to treat severe mental disorders) such as phenothiazines, which are antidepressants used for treating depression, and anticonvulsants (medications used to prevent or stop seizures) such as phenytoin can result in ophthalmoplegia. Thiamine and vitamin E deficiencies have been identified as the cause of this disorder as well.
How Is an Ophthalmoplegic Syndrome Diagnosed?
Diagnosis is made by a neurologist, a physician specializing in diagnosing and treating diseases of the nervous system; an ophthalmologist, a physician specializing in diseases of the eye; or by a neurologist who specializes in eye disorders (neuro-ophthalmologist). Diagnosis is made by a combination of thorough history taking, physical examination, and laboratory tests.
- Is the diplopia present only if both eyes are open or if only one eye is open?
- How did the diplopia start?
- How long has it been present? Is there any fluctuation in the diplopia?
- In which direction is the diplopia worse? Does it get better by covering one eye or by tilting the head?
- Is there any pain?
- Was there any trauma?
- Are there other family members with diplopia?
- Are there other eye symptoms, such as ptosis, decreased vision, or uncontrollable jerking of eyes?
- Are there other symptoms, such as headache, muscle weakness, or numbness?
- Is there any history of diabetes, stroke, migraine, or thyroid problems?
Eyes are examined for protrusion, redness, ptosis, and tenderness. Then, eye movements are examined separately in each eye and together in both eyes. A red glass or prism in front of each eye helps to pinpoint the eye and the muscle that is responsible for the false image leading to diplopia. Pupils are examined with respect to their reaction to light. A dilated eye exam is done to examine other structures, such as the retina. Finally, a thorough neurological * exam is conducted that includes systematic tests of how well various parts of the nervous system are functioning. A general physical exam may also be performed.
Laboratory testing includes a complete blood count, blood chemistry profile, and thyroid testing. Based on the history and physical exam, one or more of the following tests may be performed:
- Brain imaging by computed tomography * (CT scan) or magnetic resonance imaging * (MRI) to rule out stroke, cancer, aneurysm, or multiple sclerosis
- Electromyogram to determine muscle electrical activity
- Nerve conduction or evoked potential testing to determine nerve activity and response for conditions such as diabetes and multiple sclerosis, respectively
- Cerebrospinal fluid (fluid that surrounds the brain and spinal cord) analysis by spinal tap to detect infections, multiple sclerosis, and cancer
- Tests for electrical activity of the heart (electrocardiogram) and hearing (audiogram)
- Muscle biopsy * in conditions such as muscular dystrophy (DIStro-fee), which is a group of inherited disorders that causes muscle weakening that worsens over time
- In myasthenia gravis, testing for acetylcholine activity (Tensilon test) or to detect acetylcholine receptor antibodies
- Genetic analysis for DNA * mutation
How Is Ophthalmoplegia Treated?
Specific treatment depends on the syndrome. Myasthenia gravis is treated with corticosteroids (kor-tih-ko-STIRoyds), which are chemical substances made by the adrenal glands that have several functions in the body, including maintaining blood pressure during stress and controlling inflammation; diabetes with insulin * or medications; and multiple sclerosis with immunosuppressants (im-yoono-su-PRES-ants), which are substances that weaken the body's immune system. Medical professionals have tried Vitamin E to treat Kearns-Sayre syndrome and Coenzyme Q in progressive external ophthalmoplegia, but there is no definitive treatment for these. A pacemaker * may be needed in Kearns-Sayre syndrome. All syndromes benefit from symptomatic treatment for alleviating diplopia. The basic principle is to eliminate the abnormal image from the eye with the weak muscle by using an eye patch or special glasses with prisms, or by having surgery for ptosis.
What Is the Prognosis for Ophthalmoplegic Syndromes?
See also Dementia • Diabetes • Eye Disorders: Overview • Huntington Disease • Muscular Dystrophy • Myasthenia Gravis (MG) • Parkinson's Disease • Stroke • Tumor • Thyroid Disease