What is the Hoffman sign?
The Hoffman sign refers to the results of the Hoffman test. This test is used to determine whether your fingers or thumbs flex involuntarily in response to certain triggers.
The way that your fingers or thumbs react may be a sign of an underlying condition affecting your central nervous system. This includes the corticospinal nerve pathways, which help control movements in your upper body.
Although it may be performed as part of a routine physical exam, it usually isn’t done unless your doctor has reason to suspect an underlying condition.
Not all doctors consider the Hoffman test to be a reliable diagnostic tool by itself, because your response to the test can be affected by other factors. When it’s used, it’s typically alongside other diagnostic tests. This will allow your doctor to get a broader view of the signs from the symptoms you report.
Keep reading to learn more about the test procedure and what you may need to do if you get a positive or negative result.
How is this test done?
To perform the Hoffman test, your doctor will do the following:
- Ask you to hold out your hand and relax it so that the fingers are loose.
- Hold your middle finger straight by the top joint with one hand.
- Place one of their fingers on top of the nail on your middle finger.
- Flick the middle fingernail by quickly moving their finger down so that your nail and your doctor’s nail make contact with each other.
When your doctor performs this flicking motion, your finger tip is forced to quickly flex and relax. This causes the finger flexor muscles in your hand to stretch, which can then make your index finger and thumb flex involuntarily.
Your doctor may repeat these steps multiple times so that they can make sure your hand responds the same way each time. They may also perform the test on your other hand to see if the sign is present on both sides of your body.
If you’ve already had other diagnostic tests, your doctor may only perform the test once. This is usually the case if it’s being done to confirm a diagnosis or as part of a series of tests for a particular condition.
What does a positive result mean?
A positive result occurs when your index finger and thumb flex quickly and involuntarily right after the middle finger is flicked. It’ll feel as if they’re trying to move towards each other. This reflexive movement is called opposition.
In some cases, your body naturally reacts this way to the Hoffman test, and you may not have any underlying conditions causing this reflex.
A positive Hoffman’s sign may indicate that you have a neurological or nervous system condition that affects the cervical spine nerves or brain. If the sign is positive on only one hand, you may have a condition that only affects one side of your body.
Some of these conditions include:
- hyperthyroidism, which happens when you have too much thyroid-stimulating hormone (TSH) in your blood
- spinal cord compression (cervical myelopathy), which happens when there’s pressure on your spinal cord because of osteoarthritis, back injuries, tumors, and other conditions that affect your spine and backbone
- multiple sclerosis (MS), a nerve condition that happens when your immune system attacks and damages your body’s myelin, the tissue that insulates your nerves
What happens if I get a positive result?
If your doctor believes that a neurological or nervous condition is causing you to get a positive Hoffman sign, they may recommend additional testing.
This may include:
- blood tests
- a spinal tap (lumbar puncture) to test your cerebrospinal fluid
- imaging tests, such as an MRI scan, to look for any neurological damage in your spine or brain
- stimulus tests, which use small electrical shocks to test how your nerves respond to stimulation
These tests can help diagnose MS and other conditions that can cause a positive Hoffman sign.
For example, blood tests can help your doctor find out if you have a deficiency of thyroid stimulating hormone (TSH) and an excessive amount of thyroid hormones (T3, T4) in your blood, which can indicate hyperthyroidism.
A spinal tap can help diagnose many conditions in addition to MS, including infections and cancer.
Other symptoms that may be a sign of one of these conditions include:
- blurred vision
- pain in your back, neck, or eyes
- trouble using one or both hands
- difficulty urinating
- difficulty swallowing
- abnormal weight loss
What does a negative result mean?
A negative result occurs when your index finger and thumb don’t respond to your doctor’s flick.
What happens if I get a negative result?
Your doctor will likely interpret a negative result as normal and may not require you to get any further tests. If you get a negative result despite other symptoms and signs indicating that you have a condition like MS, your doctor will likely suggest additional tests before making a diagnosis.
How is the Hoffman sign different from the Babinski sign?
The Hoffman test is used to assess upper motor neuron function based on how your fingers and thumbs respond to stimulus, whereas the Babinski test is used to assess upper motor neuron function based on how your toes respond to stroking the bottom of your foot.
Although the two tests are often done together, their results could mean different things about your body, brain, and nervous system.
The Hoffman sign may indicate a condition that affects the cervical spinal cord, but it may happen even if you don’t have any spinal conditions.
The Babinski sign is normal in infants, but it should go away with maturation of the upper motor neurons by 2 years of age.
A positive Hoffman test or Babinski test may indicate a condition affecting your upper motor neuron system, such as amyotrophic lateral sclerosis (ALS).
The bottom line
A positive Hoffman sign isn’t necessarily a cause for concern. But your doctor may suggest additional tests if you get a positive sign and have other symptoms of conditions like MS, ALS, hyperthyroidism, or spinal compression. Whatever the result, your doctor will walk you through your options and help you determine your next steps.