Opsoclonus

What is Opsoclonus?

Opsoclonus is a condition involving eye movement referred to as oculomotor dyskinesia. People with this condition experience fast, repeated, and involuntary eye movements that don’t follow a particular rhythm. Their eyes will move in all directions: up, down, and side-to-side (torso rotation), without any break between the eye movements. This is most noticeable when the patient is awake and trying to focus their gaze. However, it continues even when they’re trying to focus their eyes, when their eyes are closed, in dark environments, and even during sleep. People suffering from opsoclonus often complain about visual blurring and shaking vision, because of the high frequency and substantial range of the eye movements.

There are other conditions that somewhat resemble opsoclonus, like opsochoria and ocular flutter. Opsochoria differs due to its uncoordinated eye movements, while ocular flutter is another type of abnormal eye movement that only happens side-to-side. Opsoclonus is unique when compared to nystagmus, another eye condition, because the phase in which the eye darts away from the target it’s looking at, always happens abruptly (saccade).

When opsoclonus appears along with other conditions like myoclonus, encephalopathy (an illness affecting the brain), tremors, impaired mental function, or changes in behavior, it’s often classified as an opsoclonus-myoclonus syndrome (OMS), also commonly known as dancing eyes and dancing feet syndrome.

What Causes Opsoclonus?

Opsoclonus and OMS (Opsoclonus-Myoclonus Syndrome), conditions that affect eye movement and muscle control, can be linked to several diseases. These range from certain types of cancer, infections, to effects of toxins and drugs. In adults, they are commonly associated with illnesses such as small cell lung cancer, breast cancer, ovarian teratoma, and less commonly, non-Hodgkin lymphoma, malignant melanoma, and kidney cancer. Research suggests that people under 40 with opsoclonus are less likely to have a cancer other than ovarian teratoma.

In children, the most common causes of opsoclonus and OMS are neuroblastic tumors, which are types of nerve tissue tumors, with over half of children with OMS also having an underlying neuroblastoma (a type of nerve cancer). Interestingly, opsoclonus in children with neuroblastoma usually indicates a better outcome. Other rare causes of opsoclonus in children include ovarian teratoma and hepatoblastoma, a rare liver cancer.

Opsoclonus can also be linked to infections such as HIV, or to the immune response to beginning HIV treatment, as well as Mycoplasma pneumonia, Salmonella enterica, and others. Certain diseases like celiac disease, sarcoidosis, and multiple sclerosis are also associated with opsoclonus.

Offending toxins could include substances such as chlordecone, organophosphates, strychnine, thallium, and toluene. Certain medications like amitriptyline, cocaine, lithium, and phenytoin with diazepam can also cause opsoclonus. In many instances, even after thorough investigations, the cause of opsoclonus may remain unknown and so these cases are classified as idiopathic, or without known cause.

Risk Factors and Frequency for Opsoclonus

Opsoclonus is extremely rare, happening to about 1 in 5 million people each year.

Signs and Symptoms of Opsoclonus

When checking a patient, it’s important to gather a detailed medical history. This can help reveal if they’ve had a previous serious disease like cancer, or a recent infection. Documenting the movement of the patient’s eyes can also provide valuable information and confirm the diagnosis. In addition, a thorough examination focusing on the patient’s neurology and eye health should be done to rule out any other possible issues.

Testing for Opsoclonus

If you have symptoms of opsoclonus or OMS, your doctor will want to run some thorough tests to understand what’s going on. This could start with a neuroimaging, a technique that provides images of your nervous system, and a lumbar puncture, a procedure in which a needle is inserted into the lower part of the spine to test the fluid that surrounds the brain and spinal cord.

Next, they’ll want to make sure that you don’t have any diseases of the central nervous system. If those tests come back clear, your doctor will then look for hidden (occult) cancer or signs of toxic, metabolic, and infection-related (para-infectious) causes. This typically involves a CT scan of your chest, stomach, and pelvis areas. If these tests don’t reveal the cause, they may then recommend a PET scan, a type of imaging test that helps reveal how your tissues and organs are working. This scan is particularly recommended for patients over the age of 40.

Even though testing for autoantibodies (proteins produced by your immune system that can end up attacking your body’s own cells) often doesn’t provide a clear diagnosis, doctors still usually recommend this test. That’s because if these antibodies are present, they could confirm a diagnosis of paraneoplastic opsoclonus or OMS. Paraneoplastic refers to disorders that are triggered by your immune system’s response to a tumor. In women, a mammogram (breast X-ray) and a thorough gynecological examination may also be performed.

If a child is being tested for opsoclonus or OMS, the doctor will want to check for the presence of neuroblastoma, a type of cancer that often starts in the adrenal glands. This typically includes imaging of the entire nervous system, and a detailed CT scan of the chest, stomach, and pelvis. They might also test the child’s urine for certain substances called catecholamines, which can indicate the presence of a neuroblastoma. In addition, they might run antibody screening tests.

In every case, if the initial investigation doesn’t provide an answer, it’s usual to re-run the tests a few months later to make sure that no hidden conditions were missed the first time around.

Treatment Options for Opsoclonus

It’s essential to identify the root cause of a medical problem, especially when it comes to detecting Paraneoplastic syndrome, a group of rare disorders triggered by an abnormal immune system response to a cancerous tumor. In people with proven cancer-related opsoclonus or OMS, a disorder affecting the nervous system, targeted cancer treatments such as surgery, chemotherapy, and radiation are usually the first course of action. Sometimes, doctors will supplement these treatments with immunotherapy if necessary.

Opsoclonus, a condition characterised by rapid, irregular eye movements, is primarily caused due to immune system activity. As a result, immunosuppression treatments, which aim to reduce the body’s immune response, have been proven effective. These treatments often use corticosteroids, a type of medication that reduces inflammation and immune system activity.

Several medicines such as prednisone or dexamethasone, or adrenocorticotropic hormone (ACTH), a hormone that helps regulate your immune system, are often used. They typically apply these treatments along with intravenous immunoglobulin (IVIG), a solution of antibodies that help control immune response. Studies suggest that IVIG shows improved results when combined with steroid therapy.

In more severe cases, doctors might combine corticosteroids or ACTH and IVIG with cyclophosphamide or rituximab, types of cancer medication. Additionally, other types of immunotherapy and plasma exchanges, a procedure that replaces the plasma in your blood, might be considered if the disease doesn’t respond to standard treatments.

Similar treatments apply to children suffering from paraneoplastic opsoclonus. Common treatments include corticosteroids, ACTH, and IVIG. If these treatments aren’t effective, doctors may consider prescribing low-dose cyclophosphamide or rituximab. Using plasma exchange can also prove useful for children with especially stubborn cases.

What else can Opsoclonus be?

When trying to diagnose OMS (Oscillopsia), physicians usually consider the following potential causes:

Neurological related causes might include:

• Benign paroxysmal positional vertigo (a type of balance-related issue)
• Cerebral vascular event (a problem related to blood vessels in the brain)
• Lateral medullary syndrome (a nerve-related condition often due to a stroke)
• Meniere’s disease (a disease that affects your balance and hearing)
• Multiple sclerosis (a disease of the brain and spinal cord)
• Tumors in the brain
• Wernicke encephalopathy (brain damage caused by a lack of vitamin B1)

Possible toxin-related causes might include:

• Alcohol intoxication
• Amphetamines (stimulant drugs)
• Barbiturates (sedatives)
• Benzodiazepines (used to treat anxiety and sleep disorders)
• Ketamine (a pain medication and recreational drug)
• Lithium (used to treat mood disorders)
• Phencyclidine (also known as PCP, a hallucinogenic drug)
• Phenytoin (a medication used to treat seizures)
• Salicylates (a type of drug that includes aspirin)
• Overuse of selective serotonin reuptake inhibitors (commonly used antidepressants)
• Thiamine deficiency (a lack of vitamin B1)

What to expect with Opsoclonus

Intensive treatment to lower immune system activity, and improvement of the condition, tend to result in better long-term neurological results. About 75% of patients, especially children, with rapid, irregular eye movements or OMS (a disorder featuring a spectrum of symptoms such as random eye movements, body trembling, weak muscles, etc.) will likely experience a return of their symptoms. The timing of reducing immune-lowering treatment often contributes to these recurrences. Recurrences of the condition usually imply worse long-term results and significant developmental disorders in children. Hence, it’s important to consider the right duration of treatment and careful reduction of immune-lowering therapy.

When the rapid, irregular eye movements condition comes without an identifiable cause, it generally has a better outlook compared to instances caused by a tumor. In children, having a neuroblastoma (a type of cancer that forms in certain nerve tissue) alongside irregular eye movements tends to have a better prognosis.

Every patient showing rapid, irregular eye movements or OMS symptoms needs careful examination to rule out hidden tumors. For adults, this condition when associated with tumors usually results from small cell lung cancer, breast cancer, or ovarian cancer. In children, neuroblastoma is the usual cause. Treatment to reduce the activity of the immune system is vital in preventing the return of symptoms and deterioration of neurological outcomes.

Possible Complications When Diagnosed with Opsoclonus

Opsoclonus is a condition that affects eye movement and is often caused by complex reactions involving certain body defense mechanisms, including those involving cells and fluids. This condition can cause balance problems that could lead to accidents like head and muscle injuries. Treatment typically involves suppressing the immune system, which can sometimes cause other infections. Further, children with certain tumors, such as neuroblastoma, may experience developmental delays.

Common Possible Consequences:

• Balance issues leading to head and muscle injuries
• Infections due to immune system suppression
• Developmental delay in children with certain tumors

Preventing Opsoclonus

Opsoclonus is a condition that affects the movement of your eyes, making it difficult to control. The exact cause of this condition isn’t readily known but is thought to be related to issues with your body’s immune system. Anyone who is suspected of having this condition, also known as OMS, must undergo thorough medical tests to rule out the possibility of hidden, or “occult”, tumors.

In adults who have opsoclonus which coincides with cancer (referred to as ‘paraneoplastic opsoclonus’), it is usually tied to lung cancer (specifically SCLC), breast cancer, or ovarian cancer. In children, the most common associated cause is often neuroblastoma, which is a type of cancer that forms in certain types of nerve tissue.

One of the important aspects of managing this condition is immunotherapy. This is a type of treatment that helps enhance or suppress the immune system to prevent relapse — a situation where the symptoms come back — and prevent the neurological condition from worsening. This therapy is essential in maintaining a more stable and improved health outcome.