which is often misheard or misspelled as

“central sensational”

What is the meaning

Definition (IASP):

an increased responsiveness of pain-processing neurons in the central nervous system (spinal cord + brain) to normal or even sub-threshold inputs.

In plain English: the pain system’s “volume knob” gets turned up, so ordinary signals feel painful and painful signals feel bigger or spread wider. The Lancet iasp-pain.org

What’s happening inside the nerves

After a strong or ongoing trigger

(e.g., a disc bulge/annular tear irritating a nerve root),

Neurons in the spinal cord’s dorsal horn can switch to a hyperexcitable state. Features include:

Lowered thresholds (things hurt more easily)
Bigger responses to the same input
Spontaneous firing (pain without a obvious trigger)
Expanded receptive fields → pain can spread beyond the original area (secondary hyperalgesia/allodynia)
These are classic lab and clinical findings of central sensitization. jpain.org SpringerLink

Two extra processes keep the volume turned up:

Descending facilitation / reduced inhibition from brainstem circuits (less “top-down braking,” more amplification). ScienceDirect JCI
Glial/microglial activation & mediators in the cord that maintain hyperexcitability (part of the biology described in foundational reviews). ScienceDirect

Why this links to back injury “ants crawling” feelings

Your imaging shows L5/S1 disc bulge + left annular tear abutting the left S1 root. That provides ongoing nociceptive/neuritic input (mechanical + chemical) that can drive central sensitization. rosslab.neurobio.pitt.edu
When the system is sensitized, symptoms can move or widen (e.g., from low back into buttock, posterior thigh, calf, lateral foot). That’s the spread/secondary hyperalgesia piece, not “in your head.” jpain.org
The “ants crawling inside the spine/deep itch” is typical of neuropathic itch (pruritus)—itch that arises from nerve injury or root irritation, not from the skin. Itch and pain share wiring; when central inhibition drops, itch can appear in normal-looking skin and follow radicular or peripheral nerve patterns. The Lancet jacionline.org
So: this is not a skin allergy; it’s an inside-the-nerves issue driven by your spinal/nerve-root problem, then amplified centrally.

Why it can “travel”

Central sensitization causes receptive field enlargement and heterosynaptic sensitization—neighboring inputs start to ring the same alarm. The result is pain/itch extending beyond one dermatome, sometimes mirrored or widespread, even when imaging shows a single main driver. iasp-pain.org jpain.org

How clinicians recognise it (clues)

Pain out of proportion to tissue findings or persistent after tissues should have settled.
Allodynia (non-painful touch hurts), hyperalgesia, symptom spread, sleep disturbance, fatigue, stress sensitivity.
In your case: long duration, severe sleep loss, shifting itch/pain, and flare-ups with sitting/stress fit this pattern described in reviews. The Lancet

Treatment: calm the driver and turn down the gain

1) Address the peripheral driver (your L5/S1 root):

Continue what helps decompress/settle the root (graded decompression, neutral-spine mechanics, avoid twisting/side-bending under load). Consider targeted procedures (e.g., epidural steroid) only if your team advises. This reduces the input that’s fueling the central amplification. (General principle from central-sensitization literature.) ScienceDirect

2) Evidence-based strategies for the central piece:

Pain neuroscience education + graded activity/exposure. Understanding the biology lowers threat and reduces amplification; pair it with gentle, regular aerobic/strength work within symptom-paced limits. ScienceDirect
Sleep restoration (huge amplifier): consistent schedule, reclined/side positions that you tolerate; consider a night-time neuropathic agent (discuss with GP). Poor sleep sustains sensitization. The Lancet
Psychological therapies that target central gain (CBT-i for insomnia; CBT/ACT for pain) improve coping and descending inhibition. The Lancet
Medications for neuropathic symptoms (choose one, titrate, switch if needed):
- Amitriptyline or nortriptyline (low dose, especially at night),
- Duloxetine,
- Gabapentin or Pregabalin.
  NICE and NHS guidance support these first-line options; rotate if not effective/tolerated. (Opioids generally poor for central pain.) NICE hweclinicalguidance.nhs.uk bucksformulary.nhs.uk
Pacing & flare plans: short sitting bouts with micro-breaks; substitute bike/pool when treadmill provokes neural tension.

3) For neuropathic itch specifically:

Treat the underlying nerve source (root irritation).
The same neuropathic pain meds can help neuropathic itch in some patients; refractory cases sometimes trial topical/local treatments depending on the exact diagnosis. (Overview reviews.) The Lancet jacionline.org

Prognosis

Central sensitization is reversible in many people,

especially when the peripheral driver is reduced and you steadily rebuild sleep, fitness, and confidence. It can predict

slower recovery if unaddressed—

so your current shift to decompression,

careful loading, and sleep strategy is on the right track. The Lancet

Quick “is / is not” recap for your report

Is: a nervous-system processing change
(spinal cord/brain) that amplifies pain/itch signals and can spread symptoms. jpain.org
Is not: a skin allergy or purely psychological problem.
Your “ants inside the spine” feeling fits neuropathic itch
from nerve/root irritation with central amplification.
The Lancet

Your next steps (practical)

Keep neutral-spine mechanics, ≤10 kg, no twisting/side-bending under load.
Swap provocative treadmill days for bike/other forms of exercise; use intervals if walking.
Enforce micro-breaks when sitting (≤10–15 min → stand/walk 2–3 min).
Prioritize sleep;
I am avoiding medication,
I use food as medications
Not medications as food
Track daily: pain (0–10), sleep, sitting tolerance, and minutes of gentle activity.

“central sensitization”