It lasts just a few seconds, but it can be startling: An intense burst of pain like an electric shock that runs down your back into your arms and legs when you move your neck. It’s called Lhermitte’s sign, or barber chair sign, and it’s often one of the symptoms that people mention when they’re first diagnosed with multiple sclerosis.
The problem can be painful, but it’s not life-threatening. With time or with treatment, some people stop having Lhermitte’s sign.

What’s Really Going On?

When you have MS, your immune system begins to attack the fatty coating, called myelin, that protects your nerves. Without it, scar tissue forms and begins to block the messages traveling in your brain and spinal cord. Lhermitte’s sign is one of the symptoms that happens when those signals don’t move like they should.
MS is not the only condition that can cause Lhermitte’s. It can also happen to people with other disorders involving the upper part of the spinal cord, and to people with a severe lack of vitamin B12. Your doctor will want to test you to see if MS or another health problem is causing your symptoms.

Treatment and Therapy

Like a lot of MS symptoms, you’re more likely to trigger Lhermitte’s sign if you’re tired or overheated. It can also happen if you move your head the wrong way, often when your chin hits your chest.