What is central sensitization?

Central sensitization is a condition in which the central nervous system amplifies pain signals beyond what the original injury or tissue damage warrants. The spinal cord and brain become hypersensitive, so stimuli that should feel mild or painless register as painful. It is a key driver of chronic pain conditions including fibromyalgia, complex regional pain syndrome (CRPS), chronic migraines, and neuropathic pain. The International Association for the Study of Pain now uses the term nociplastic pain to describe pain arising from this altered nociceptive processing.

How does ketamine treat central sensitization?

Ketamine is a noncompetitive antagonist of NMDA receptors, which are the primary drivers of central sensitization. When pain signals repeatedly activate NMDA receptors in the spinal cord, the nervous system becomes increasingly sensitive through a process called wind-up. By blocking these receptors, ketamine interrupts the cycle of amplification, reduces wind-up, and can lower the nervous system's baseline excitability. Evidence also suggests ketamine has anti-inflammatory effects at spinal and cortical levels and can alter connectivity among pain-processing brain regions.

Which chronic pain conditions involve central sensitization?

Many chronic pain conditions involve central sensitization as a core mechanism. These include fibromyalgia, complex regional pain syndrome (CRPS), chronic migraines, neuropathic pain, irritable bowel syndrome, chronic pelvic pain, temporomandibular disorders, and post-surgical chronic pain. The common thread is that the nervous system has become amplified beyond the scope of any identifiable tissue damage, producing pain that persists after the original cause has resolved or that exceeds what the underlying pathology explains.

How long does pain relief last after ketamine infusions?

Duration of relief varies by condition and individual. For CRPS, clinical evidence shows multi-day ketamine infusions can provide pain relief lasting 8 to 12 weeks. For other centralized pain conditions, a standard series of six infusions over two to three weeks typically produces initial benefit, with maintenance infusions individualized based on response. Some patients sustain improvement for weeks to months between sessions. The theory is that by interrupting the sensitization cycle, ketamine gives the nervous system an opportunity to reset toward a less amplified baseline.

Is ketamine effective for fibromyalgia pain?

Fibromyalgia is characterized by widespread pain that research has linked to central sensitization and elevated glutamate levels in pain-processing regions of the brain. Because ketamine directly targets the NMDA receptor and glutamate system that drive this sensitization, there is a mechanistic rationale for its use. Clinical evidence is mixed but growing. Some patients experience meaningful reduction in pain severity and improved function. At our clinic, we assess each fibromyalgia patient individually and discuss realistic expectations based on their symptom profile and treatment history.

Ketamine and Central Sensitization: Why It Helps So Many Pain Conditions

The Volume Knob Problem

Here is a simplified way to think about what has gone wrong in chronic pain: the nervous system has a volume knob for pain signals, and in certain conditions, that knob gets turned up and stuck. A stimulus that should register as mild discomfort gets amplified into significant pain. A stimulus that should not be painful at all—a light touch, a change in temperature, clothing against skin—registers as agony. The original injury may have healed months or years ago, but the nervous system is still broadcasting at maximum volume.

This is central sensitization, and it is not a theory or a metaphor. It is a measurable neurobiological state in which neurons in the spinal cord and brain have become hyperexcitable, responding more aggressively to incoming signals than they should. The International Association for the Study of Pain (IASP) now classifies the pain it produces as nociplastic pain—a distinct third category alongside nociceptive pain (caused by tissue damage) and neuropathic pain (caused by nerve injury).

Central sensitization is now understood to be a core mechanism in conditions we have written about elsewhere on this blog: fibromyalgia, CRPS, chronic migraines, neuropathic pain, and chronic pain broadly. The reason ketamine can help with all of these conditions is that it targets the molecular machinery that drives the sensitization itself.

How the Nervous System Gets Stuck

Under normal circumstances, pain works as an alarm system. You touch a hot stove, pain neurons fire, you pull your hand back. The system does its job and returns to baseline. The alarm turns off when the danger passes.

Central sensitization develops when pain signals are sustained or repeated enough that the spinal cord neurons processing those signals undergo a change in their responsiveness. The mechanism involves a specific receptor on these neurons: the NMDA receptor.

Here is how the process works:

Initial pain signals arrive at the dorsal horn of the spinal cord, where they activate AMPA receptors on spinal neurons. This produces a normal, proportionate pain response.
With repeated or sustained signaling, the persistent activation removes a magnesium block from the NMDA receptor, allowing it to open. Once open, the NMDA receptor allows calcium to flood into the neuron.
This calcium influx changes the neuron’s excitability. The neuron becomes easier to activate and responds more vigorously to subsequent signals. This is wind-up—a progressive increase in neuronal firing in response to repeated stimuli.
If the process continues, structural and functional changes consolidate. More NMDA receptors are produced and expressed on the cell surface. Glial cells (astrocytes and microglia) become activated and release inflammatory mediators that further amplify signaling. The neuron’s threshold drops permanently. What used to require a strong signal to fire now fires at a whisper.

The result is a nervous system that has learned to amplify pain. The original injury may be fully healed, but the spinal cord is still behaving as though the emergency is ongoing. This is why patients with chronic pain often hear “we can’t find anything wrong”—the problem is not in the tissue. It is in the processing.

The Conditions This Connects

Once you understand central sensitization as a shared mechanism, the overlap between seemingly unrelated chronic pain conditions starts to make sense.

Fibromyalgia is perhaps the most recognized centralized pain condition. Patients have widespread pain with no identifiable tissue damage. Research published in the Journal of Pain Research (2025) found elevated glutamate levels in the insular cortex and anterior cingulate of fibromyalgia patients, with glutamate concentrations correlating directly with pain severity. Reduced GABA (the brain’s inhibitory neurotransmitter) was found in the same regions, meaning both the accelerator and the brake are broken: too much excitation, too little inhibition.

Complex regional pain syndrome (CRPS) often begins after an injury—a fracture, surgery, or even a minor sprain—but the pain that develops is wildly disproportionate to the triggering event and persists long after healing. The affected limb may become swollen, discolored, and exquisitely sensitive to touch. Research has demonstrated that CRPS involves both peripheral and central sensitization, with NMDA receptor activation driving the central component.

Chronic migraines involve sensitization of the trigeminal system, the nerve pathway responsible for head and face sensation. With repeated migraine episodes, neurons in the trigeminal nucleus become hyperexcitable, lowering the threshold for subsequent attacks and expanding the area of pain. Patients who have had migraines for years often describe the attacks becoming more frequent, harder to treat, and involving broader regions of the head and neck—a clinical pattern that maps directly to progressive sensitization.

Neuropathic pain from conditions like diabetic neuropathy, post-herpetic neuralgia, or chemotherapy-induced peripheral neuropathy involves damage to the nerves themselves, but the severity and persistence of pain often exceeds what the peripheral nerve damage alone explains. Central sensitization accounts for this gap: the spinal cord has amplified the already abnormal signals from damaged nerves.

A 2025 review in the Journal of Pain Research described central sensitization as the “shared mechanism” across fibromyalgia, osteoarthritis, and inflammatory arthritis, noting that excessive NMDA and AMPA receptor activation, elevated glutamate, and reduced GABA constitute a common neurochemical signature. The same review noted that activated glial cells sustain neuroinflammation in all three conditions, perpetuating the sensitized state.

Why Ketamine Fits This Problem

Ketamine is a noncompetitive antagonist of the NMDA receptor. This means it binds inside the receptor channel and blocks it, preventing the calcium influx that drives sensitization. It is the most widely studied NMDA receptor antagonist in clinical pain medicine.

A 2026 review published in Current Pain and Headache Reports (Springer Nature) described ketamine’s analgesic mechanisms in the context of central sensitization:

As a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine attenuates central sensitization, modulates opioid tolerance, and enhances descending inhibitory control. — Current Pain and Headache Reports, 2026

The review detailed several mechanisms through which ketamine addresses centralized pain:

Wind-up reduction. By blocking NMDA receptors in the dorsal horn of the spinal cord, ketamine directly interrupts the progressive amplification of pain signaling. The neurons cannot undergo the calcium-mediated changes that make them hyperexcitable.
Descending inhibition enhancement. The brain has its own pain-suppression system—descending pathways from the brainstem that send inhibitory signals down to the spinal cord to modulate pain processing. In chronic pain states, these inhibitory pathways often become impaired. Evidence suggests ketamine helps restore their function.
Neuroinflammation modulation. Research has identified anti-inflammatory effects of ketamine at both spinal and cortical levels, including effects on activated glial cells that sustain chronic neuroinflammation.
Pain circuit remodeling. Through the same BDNF-mediated synaptogenesis that underlies its antidepressant effects, ketamine may alter connectivity among pain-processing brain regions, shifting the system away from its amplified baseline.

A Cochrane review and additional systematic reviews have found that for CRPS specifically, there is moderate-certainty evidence supporting the use of ketamine infusions for analgesia, with pain relief lasting 8 to 12 weeks following multi-day protocols. For neuropathic pain more broadly, evidence supports short-term analgesic benefit with IV ketamine.

Not Just Pain Relief: Breaking the Cycle

An important distinction about ketamine in chronic pain: the goal is not just temporary pain reduction, although that matters. The goal is to interrupt the sensitization cycle long enough for the nervous system to recalibrate.

Think of it in terms of the volume knob analogy. If you could turn down the volume on pain signals for a sustained period, the neural circuits that have been locked into amplification mode have an opportunity to return toward a normal baseline. The NMDA receptors are no longer being continuously activated. The glial cells have a chance to quiet down. The descending inhibitory pathways can begin to reassert themselves.

This is a theory, not a proven mechanism, and we want to be honest about that. But it aligns with what many chronic pain patients describe after a ketamine infusion series: not just reduced pain during the infusions, but a period afterward where the pain stays lower than its previous baseline. The nervous system seems to have stepped down from its amplified state, at least partially.

This effect is not permanent for most patients, which is why maintenance protocols exist. But each infusion series may be thought of as a window of opportunity—a period in which physical therapy, movement, sleep improvement, and other rehabilitation strategies can be pursued with less pain interference. Pain reduction without functional improvement is incomplete treatment. Pain reduction combined with restored function is where meaningful recovery happens.

The Depression Connection

There is a reason many patients with chronic pain also have depression, and it is not just that living in pain is depressing (although it is). Central sensitization and depression share overlapping neurobiology.

Both involve glutamatergic dysfunction. Both involve reduced BDNF and impaired synaptic plasticity. Both involve neuroinflammation mediated by activated glial cells. Both involve impaired prefrontal cortex function. The two conditions feed each other: chronic pain worsens depression, and depression lowers pain thresholds and impairs the brain’s ability to modulate pain signals.

Ketamine addresses both conditions through shared molecular pathways. For patients who carry both chronic pain and treatment-resistant depression, this dual mechanism is particularly relevant. Treating the pain and the depression with the same intervention, through the same set of infusions, is more efficient and often more effective than treating them separately with different medications.

What Treatment Looks Like at Our Clinic

At Music City Ketamine, we treat chronic pain patients whose conditions involve central sensitization as a significant component. During the initial consultation, we discuss your pain history: the original onset, how it has evolved over time, what treatments you have tried (medications, nerve blocks, physical therapy, surgery), and how much the pain has restricted your daily function. We also screen for co-occurring depression and anxiety, which frequently accompany chronic pain and influence treatment planning.

Marla Peterson, CRNA, administers and monitors every session. For chronic pain, the infusion protocol may differ somewhat from the protocol used for mood disorders—dosing, duration, and frequency are adjusted based on the specific pain condition and individual response. We typically begin with a series of six infusions and assess progress along the way.

We encourage patients to use the pain reduction period following infusions to re-engage with physical therapy, movement, sleep hygiene, and other rehabilitation strategies. The infusion opens a window; what you do during that window matters. Safety information and pricing details are available on our website.

For patients in Franklin, Nashville, Brentwood, Cool Springs, Murfreesboro, and the broader Middle Tennessee area, our clinic is located at 480 Duke Dr., Suite #100 in Franklin.

Ketamine and Central Sensitization: Why One Treatment Helps So Many Pain Conditions