How does Dawson's finger relate to multiple sclerosis?
Dawson's finger lesions can help a doctor diagnose multiple sclerosis (MS) when other symptoms, such as difficulties with movement or thought processes, accompany them.
MS is a chronic disease that targets the central nervous system (CNS), which consists of the brain and spinal cord. Symptoms occur when the immune system develops extreme sensitivity and begins attacking the body.
In people with MS, the immune cells attack myelin, a fatty sheath that covers the nerve cells. This process is called demyelination.
Without myelin, nerves cannot send and receive information effectively, causing a range of symptoms that vary from person to person. Given this range of symptoms, Dawson's finger is a useful indicator of MS.
In this article, we explain Dawson's finger, its relationship with MS, and its role in diagnosis.
Dawson's finger and MS diagnosis
Dawson's finger is a lesion that might develop in people with MS.
In 1916, Dr. James Walker Dawson noticed a pattern of plaques in the brains of people with MS. Now, these so-called lesions that doctors call Dawson's fingers are a typical sign of MS.
In one 2014 study, researchers identified Dawson's finger in a majority of participants with MS. Two researchers looked at the brains of the same participants. One reported Dawson's fingers in 92.5% of people with MS, and the other researcher noted their presence in 77.5% of people.
Demyelination leaves behind plaques in the brain. These are often visible on brain scans. Dawson's finger develops around a band of nerve fibers that connect the brain's left and right hemispheres. The plaques form at right angles around veins in the brain's ventricles.
The presence of Dawson's fingers on a brain scan alone is not enough to for a doctor to diagnose MS, however. Depending on the type of evidence and the part of the body involved, a doctor will seek evidence of at least one attack and one lesion before confirming an MS diagnosis.
When doctors examine a Dawson's finger lesion, they use it to judge the spread, or dissemination, across the nervous system.
Dissemination in space (DIS) of a lesion suggests the extent of the disease's spread, while dissemination in time (DIT) can suggest multiple attacks. A doctor can use the dissemination of the lesion to predict the progression of the disease.
Before confirming MS, a doctor must find no evidence that another condition, such as an infection or brain injury, caused the symptoms.
Dawson's fingers are just one sign of damage that can point toward MS. If a brain scan shows Dawson's fingers, but a person has no other symptoms, or if they have only had one MS attack, their doctor might continue to monitor them.
The doctor may not confirm a diagnosis of MS until a person presents more symptoms.
Other MS tests
MRI brain and spinal cord scans check for a number of changes in the CNS and not only Dawson's fingers.
Doctors will check for signs of demyelination in the brain and spinal cord. Brain scans can also help to track the progression of MS over time.
Sometimes, scans show lesions in an area of the brain that does not produce symptoms of MS. These lesions offer an early warning that a person may eventually develop symptoms of the condition, however.
A doctor can use the presence of any of these lesions to request further testing, such as a brain MRI, to confirm the diagnosis. This intervention allows a person to start a course of treatment early and address symptoms before they can become disruptive.
Some other tests that support an MS diagnosis include:
- Lumbar puncture: A doctor may use this to collect cerebrospinal fluid (CSF). In this spinal fluid, they might find oligoclonal bands. These bands are products of autoimmune activity in the CSF that might indicate a range of inflammatory disorders in the CNS, including MS.
- Evoked potentials test: This test measures electrical activity in the brain, indicating how the nerves are communicating with one another.
- Optical coherence tomography: This technique uses imaging to look at the nerves at the back of the eye, which may also indicate problems.
The doctor will also check whether symptoms have developed due to any other illness. A history of the individual's symptoms can help the doctor determine which tests are most appropriate for confirming MS and ruling out other conditions.
Dawson's fingers and other brain disorders
Although Dawson's fingers do not usually develop due to other brain disorders, not everyone with Dawson's fingers displays symptoms of MS.
As brain scans are not always clear, a doctor could also mistake different brain changes for Dawson's fingers.
A 2014 study explored the ability of medical evaluators to differentiate symptoms of MS from symptoms of neuromyelitis optica spectrum disorders (NMOsd). NMOsd are immune-mediated disorders that, like MS, trigger demyelination. However, NMOsd typically target optic nerves, therefore affecting a person's vision.
One evaluator saw Dawson's fingers in an individual with NMOsd, suggesting that others might either misinterpret MRI findings or that Dawson's fingers may be present in some other medical disorders.
Symptoms of MS
MS may lead to vision problems.
Symptoms of an MS attack must have occurred alongside Dawson's finger lesions before a doctor will diagnose the disease. However, a doctor can use the presence of any lesions to request further imaging tests.
Symptoms may be subtle at first. Early warning signs of MS include:
- eye problems, including blurred vision and pain when moving the eyes.
- unusual or uncomfortable sensations, such as tingling, numbness, or an electrical shock sensation in the limbs.
- unexplained itchiness in the body.
- severe fatigue, particularly in response to extreme temperature changes.
- unexplained muscle pain and weakness.
- difficulty walking and problems with balance or coordination.
- ringing in the ears
- changes in bladder or bowel function
- feelings of "brain fog" or unclear thinking
As the disease attacks more myelin sheaths, the symptoms may progress. Most people with MS experience periodic attacks, or relapses, followed by brief improvements. However, symptoms can vary widely in people. Several types of MS might develop that progress and flare at different rates.
As the disease progresses, the attacks may become more frequent, and symptoms may include:
- long-term fatigue that interferes with daily life
- stiffness and uncontrollable muscle spasms
- muscle weakness that can limit mobility
- sexual dysfunction
- emotional difficulties, such as depression, mood swings, and involuntary laughter or weeping
- loss of bladder or bowel control
Less frequently, other symptoms can occur. These include:
Occupational and physical therapy can help people with MS return to work and social life.
MS is a chronic illness with no known cure. However, starting treatment as soon as possible provides the best chance of limiting symptoms. Identifying Dawson's finger lesions can improve the possibility of receiving an early diagnosis.
Because symptoms tend to appear in the form of attacks and then resolve later, a person might experience extended periods without an MS recurrence. In rare circumstances, some people with MS stop experiencing attacks altogether.
If attacks are not severe or disruptive, a person may not need treatment to manage the effects of the disease. Most treatment focuses on increasing the remission periods between attacks and reducing the severity of the attacks.
- Lifestyle changes: Exercise, yoga, dietary changes, and stress management may improve symptoms and quality of living in some people with MS.
- Muscle relaxants: These can help reduce the frequency and intensity of muscle spasms.
- Physical, occupational, and speech therapy: Various therapies can help slow the loss of physical and social function, improve muscle strength, and support a person's return to a good quality of life.
- Alternative and complementary treatments: Some people with MS use massage, acupuncture, or other forms of alternative medicine to manage symptoms. There is no clear evidence that these strategies work, though some people report improvements.
- Medications: Drugs, such as steroids, aim to decrease the inflammation that damages the nerve coverings.
- Plasma exchange therapy, or plasmapheresis: The doctor withdraws blood from a large vein, separates the plasma, removes harmful antibodies, and transfuses the blood back into the body. Some people who try corticosteroid treatment during a relapse without results may benefit from plasmapheresis.
An individual with MS might also need to take one or several drugs to support their symptom management. Some will be oral medications, while others take the form of an injection.
These treatments can include:
- Stimulants to help a person manage individual symptoms, including fatigue, depression, and anxiety.
- Pain medication, which can help the individual manage headaches, muscle pain, and other uncomfortable symptoms of MS.
- Drugs for treating relapses, including ocrelizumab, siponimod, and cladribine.
- Steroid drugs, which may help reduce inflammation but do not have any long-term effects on disease progression.
- Immunosuppressant drugs, which inhibit the immune response that causes demyelination.
- Disease-modifying therapies (DMTs), such as beta-interferon, that help reduce the frequency of MS attacks.
The symptoms of MS vary in their severity and effects, so a doctor may need to monitor the benefits or harm of a particular medication and make changes to support health and recovery.
Although MS can reduce a person's quality of life, it is rarely fatal. Many people with MS live full and active lives.
While some doctors find it challenging to diagnose and predict MS, recognizing Dawson's finger lesions in a scan of the CNS can help limit the progression of the disease.
However, the course of the disease is unpredictable, with symptoms ranging from relatively minor to debilitating. Symptoms tend to get worse over time as demyelination occurs in an increasing number of nerve sheaths.
MS does not always progress this way, however. Some people with MS may spend years in remission without experiencing the effects of the disease.
Tracking symptoms over time may assist people in predicting their next attack. Logging symptoms can also make it easier to get a diagnosis and help people assess whether medications and lifestyle management strategies are working.