Anti-seizure medications: Relief from nerve pain

Anti-seizure medications were originally designed to help people who have epilepsy. But the nerve-calming qualities of some of these drugs can also help quiet the burning, stabbing or shooting pain often caused by nerve damage.

Why does it hurt?

Nerves can be damaged by many things, including injury, surgery, disease or exposure to toxins. The damaged nerves are activated inappropriately and send pain signals that don't serve a useful purpose. This type of pain can be debilitating and difficult to control.

Nerve damage (neuropathy) can be caused by many conditions, including:

• Diabetes. High blood sugar levels, common in diabetes, can damage nerves throughout the body, but the first symptom typically is numbness and pain in the hands and feet.
• Shingles. Anyone who has had chickenpox is at risk of shingles, a rash of blisters that can be painful or itchy. A condition called postherpetic neuralgia occurs if shingles pain persists after the rash disappears. Because the risk of shingles increases with age, everyone age 60 and older should receive the zoster vaccine (Zostavax), which can help prevent this painful condition.
• Chemotherapy. Some chemotherapy drugs can damage nerves, causing pain and numbness that typically begin in the tips of your toes and fingers.
• Herniated disk. Nerve damage can occur if a herniated disk in your spine squeezes a nerve passing through your vertebrae too tightly.
• Inherited neuropathies. Some neuropathies are passed on genetically and can affect different nerves, depending on the type of disorder. The most common hereditary neuropathy is Charcot-Marie-Tooth disease, which affects your motor and sensory nerves.

How do anti-seizure drugs help?

The exact mechanism of action isn't fully understood, but anti-seizure medications appear to interfere with the overactive transmission of pain signals sent from damaged nerves.

Some anti-seizure drugs work particularly well for certain conditions. Carbamazepine (Carbatrol, Tegretol) is widely prescribed for trigeminal neuralgia, a condition that causes searing facial pain that feels like an electric shock.

It's important to note that the Food and Drug Administration has issued a warning that all anti-seizure drugs are associated with a slightly increased risk of suicidal thoughts or actions. Talk to a doctor or counselor promptly if you experience feelings of depression or suicidal thoughts.

Newer anti-seizure drugs may have fewer side effects

More recent and more rigorous research supports the use of the following newer anticonvulsants to help relieve pain caused by damaged nerves.

• Gabapentin (Neurontin)
• Pregabalin (Lyrica)
• Lamotrigine (Lamictal)

Gabapentin and pregabalin
Both gabapentin and pregabalin are particularly effective in the treatment of postherpetic neuralgia, diabetic neuropathy and pain caused by a spinal cord injury. Pregabalin may also help fibromyalgia. Because these drugs have few side effects — typically, drowsiness and dizziness — and are usually well tolerated, they are often the first medications to try for neuropathic pain.

Lamotrigine
Lamotrigine has proved effective in treating trigeminal neuralgia, nerve pain experienced after a stroke and HIV neuropathy (particularly in people with HIV taking antiretroviral therapy). It may also be helpful for diabetic neuropathy. If you develop a rash while taking lamotrigine, see your doctor right away because it may indicate a severe skin reaction that requires emergency treatment, such as Stevens-Johnson syndrome.

Side effects limit use of older anticonvulsants

Anti-seizure drugs have been used to treat nerve pain for many years, but their use was limited by the severity of side effects they produce.

Older anti-seizure drugs include:

• Carbamazepine (Carbatrol, Tegretol)
• Oxcarbazepine (Trileptal)
• Phenytoin (Dilantin)
• Valproic acid (Depakene)

Side effects may include:

• Liver damage
• Nausea
• Vomiting
• Double vision
• Loss of coordination
• Drowsiness
• Headache

If you take an older anticonvulsant, you typically need regular follow-up visits so your doctor can monitor for side effects. Because these older drugs generally have more side effects than do the newer anticonvulsants, and the evidence supporting use of the older anticonvulsants for neuropathic pain is sparse at times, they often are recommended only when the newer medications prove ineffective.

Research continues

As scientists learn more about the way anti-seizure drugs work, this information will be useful in determining which drugs may work best for different types of nerve pain. Pain caused by nerve damage can be disabling, but anti-seizure drugs sometimes provide relief.

Related

• Slide show: How your brain works
• Electromyography (EMG)
• Biofeedback
• Hypothyroidism: Can it cause peripheral neuropathy?
• Diabetic neuropathy
• Hypothyroidism (underactive thyroid)
• Peripheral neuropathy