One of my brightest neurologists said that memantine is highly specific for trigeminal nerve pain and there are a bunch of studies (below) showing reduced nerve pain in general with memantine…
After a few-month break from memantine in which I had a lot of horrible flare-ups I realize that memantine had helped me to have fewer flare-ups of severe cranial nerve pain, including trigeminal nerve pain. I’m back on it.
Memantine has a very low side effect profile. For what it’s worth, it’s the only medication for neuropathic pain that I’ve been able to take daily without any cognitive side effects. It might even help me to concentrate. It seems from peer-reviewed studies that 10 mg once per day is a common dose. I started at just 5 mg/day this time around. (It has a very long half-life, but still many headache docs suggest taking it twice per day.)
https://scholar.google.com/scholar?hl=en&as_sdt=0%2C33&q="neuropathic+pain"+memantine&btnG=
About the mechanism:
"Neuropathic pain usually arises due to injury or from dysfunction of the nervous system. This injury leads to increased glutamate production which being major excitatory neurotransmitter in the central nervous system leads to excitatory neurotransmission through postsynaptic receptors. During this phase of injury, there is an excess of glutamate receptors due to increased production of glutamate, increase in the functioning of glutamate receptors, and decreased metabolism of glutamate. Simultaneously, N-methyl D-aspartate (NMDA) mediates the release of substance P from the dorsal horn, leading to central sensitization by facilitating synaptic changes, and also increases the release of glutamate via presynaptic receptors.[2]
NMDA receptors are ionotropic receptors, which mediate neurotransmission via glutamine. Excessive NMDA receptor activity leads to excitotoxic cell death and is thus responsible for spasticity along with manifestations of acute pain, thereby progressing to chronic neuropathic pain if untreated or if the ongoing insult is not addressed. Based on this knowledge, NMDA-receptor antagonists are developed to treat neuropathic pain.[3]
Magnesium, ketamine, amantadine, memantine, and dextromethorphan are the drugs classified as NMDA-receptor antagonists…"