Positive effect of medicine on neuropathic pain disorder

Medication for epilepsy also has an effect on small fiber neuropathy

Researchers at the Maastricht UMC+ have shown that lacosamide has a positive effect in patients with small fiber neuropathy, a condition causing continuous neuropathic pain. The medicine reduced pain, improved sleep and had a positive effect on the overall wellbeing. The results were previously published in the journal Brain. Bianca de Greef obtained her PhD in small fiber neuropathy.

Small fiber neuropathy (SFN) is characterized by continuous burning or irritating pain. The sensations can be different from patient to patient. The pain is caused by malfunctioning of the small nerve fibers. Different underlying conditions in SFN are described, such as gene mutations, diabetes mellitus or chemotherapy. To date, there is no effective treatment for the disease. Yearly, 450 patients with SFN are visiting the Maastricht University Medical Center+.

Overactive sodium channels
Scientists from Maastricht demonstrated in earlier studies that the pain is associated with the overactivity of so-called sodium channels in the nerve fibers. With a 'normal' pain sensation, those channels become active to send the 'pain' signal to the brain. In patients with small fiber neuropathy there is a continuous signal to the brain, with continuous pain as a consequence. De researchers thought that blocking the overactive sodium channels might be the key to success. Lacosamide is a medicine that is normally used for epilepsy and indeed blocks the sodium channels from being overactive.

Positive effect
In the study, 24 patients with a hereditary form of small fiber neuropathy were divided into two groups. One group started with lacosamide for a period of eight weeks, followed by treatment with a placebo (a pill without an active agent). The other group started with placebo, followed by treatment with lacosamide. Neither the patients nor the researcher knew in which period they received lacosamide. In nearly 60 percent of patients, the pain had decreased with lacosamide use (21 percent with placebo). Moreover, around one third of the patients experienced an improvement in their overall wellbeing by using lacosamide (only 4 percent with the placebo). On top of that, also their sleep was less interfered by pain.

Other patients
Even though the medicine was tested in a specific group of patients with small fiber neuropathy (i.e. a hereditary variant), it can be expected to benefit other patients as well. "After all, something goes wrong with the sodium channels of all these patients," says PhD student De Greef. "Lacosamide has a specific effect on this. It is therefore expected that the medicine has a positive effect on other patients, but we still have to find out first."

The research about the effect of lacosamide in small fiber neuropathy was made possible with support from the Princess Beatrix Spierfonds.