Skip to main content

Health condition · Clinically reviewed

Arachnoiditis, nerve root scarring, neuropathic pain and the right specialist team.

A difficult, often disabling spinal condition. With careful assessment, modern neuropathic pain treatment and MDT support, most patients can regain meaningful function.

WhatsApp us
A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE, British Pain Society and peer-reviewed neurosurgical sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK pain and neurosurgery practice, including neuromodulation and MDT pain clinic pathways.

Key facts

Arachnoiditis at a glance.

The essentials, in plain English. What it is, why it happens and how UK pain and neurosurgery teams approach it.

  • What it is

    Inflammation and fibrosis of the arachnoid membrane surrounding the spinal cord and nerve roots, often with adhesive clumping of roots.

  • Causes

    Spinal surgery, meningitis or infection, intrathecal chemicals, subarachnoid haemorrhage or major spinal trauma.

  • Adhesive arachnoiditis

    The severe end of the spectrum, where nerve roots clump and tether to the thecal sac, visible on MRI.

  • Symptoms

    Chronic burning, tingling and numbness in the lower back, buttocks and legs, with bladder, bowel and sexual dysfunction.

  • Diagnosis

    MRI of the spine with a specialist neurology and pain assessment to exclude other structural causes.

  • Treatment

    Neuropathic pain medication, selective neuromodulation and MDT pain rehabilitation, avoiding further surgery where possible.

Why this guide matters

A rare condition that needs the right team.

Arachnoiditis is under-recognised and often misdiagnosed. The three points below shape the assessment and treatment plan on this page.

  • The cause matters

    Post-surgical, post-infective, chemical, post-haemorrhagic and post-traumatic arachnoiditis each need slightly different assessment and MDT input.

  • MRI is the key test

    Nerve root clumping, the empty thecal sac sign and adhesions on high-quality spinal MRI confirm the diagnosis and exclude other structural causes.

  • Surgery is usually avoided

    Further open spinal surgery often produces more scar tissue and worsens pain. Neuromodulation and MDT rehabilitation are the mainstays.

How the diagnosis is made

From first symptoms to a clear plan.

The steps a UK pain specialist or neurosurgeon will normally follow, in order, so you know what to expect and why.

  1. 01

    Assessing

    Detailed history and cause

    Prior spinal surgery, epidural or intrathecal injections, meningitis, spinal trauma or haemorrhage all point towards arachnoiditis.

  2. 02

    Assessing

    Neurological examination

    Motor, sensory, reflex and sphincter assessment maps the nerve roots involved and looks for cauda equina features.

  3. 03

    Assessing

    Pain phenotyping

    Burning, tingling, allodynia and spontaneous shooting pains suggest a neuropathic mechanism that guides treatment.

  4. 04

    Confirming

    MRI spine with contrast

    The key test. Look for nerve root clumping, the empty thecal sac sign, adhesions and any syrinx or hydrocephalus.

  5. 05

    Confirming

    Exclude other causes

    Rule out disc prolapse, spinal stenosis, tumour, infection and vascular malformation before settling on arachnoiditis.

  6. 06

    Planning

    Electromyography and nerve tests

    EMG and nerve conduction studies clarify which roots are affected and quantify neuropathic involvement.

  7. 07

    Planning

    Pain clinic and MDT review

    Referral to a specialist pain clinic, with neurosurgery input for selected refractory or complicated cases.

Typical timeline: a full workup and MDT plan usually within a few weeks of specialist referral.

Symptoms

What arachnoiditis actually feels like.

A chronic neuropathic pattern of pain, sensory change and autonomic disturbance. And the features that need same-day emergency attention.

  • Burning back and leg pain

    Constant burning, tingling or crawling sensations in the lower back, buttocks and legs, often worse at night.

  • Numbness and paraesthesia

    Patchy loss of sensation and pins and needles in a nerve root distribution, often bilateral.

  • Muscle cramps and spasms

    Painful lower limb cramps, spasms and visible fasciculations that disturb sleep and mobility.

  • Bladder and bowel dysfunction

    Hesitancy, urgency, incontinence or constipation from involvement of sacral nerve roots.

  • Sexual dysfunction

    Reduced sensation, erectile dysfunction or loss of orgasm, an often under-recognised feature of sacral root involvement.

  • Balance and gait problems

    Weakness, unsteadiness and falls from proprioceptive loss and lower limb pain.

  • Autonomic and skin changes

    Sweating changes, temperature intolerance and skin colour changes in the affected limbs.

  • Red flag - cauda equina features

    New saddle anaesthesia, urinary retention or rapidly progressive weakness needs same-day emergency spinal assessment.

Treatment

How arachnoiditis is treated in the UK.

Neuropathic pain medication and MDT rehabilitation first, with selective interventional and neuromodulatory options for refractory pain. Further surgery is generally avoided.

  • Gabapentin or pregabalin

    First-line neuropathic pain agents, titrated slowly to balance benefit against sedation and cognitive side effects.

  • Amitriptyline or nortriptyline

    Low-dose tricyclics at night, useful for burning pain, sleep disturbance and low mood in chronic pain.

  • Duloxetine

    An SNRI licensed for neuropathic pain, particularly helpful when depression or fibromyalgic overlap is present.

  • Selective long-term opioids

    Reserved for severe refractory pain, prescribed under a specialist pain clinic with clear function and dose review.

  • Sacral pulsed radiofrequency

    A neuromodulatory interventional option for selected sacral root pain, using pulsed rather than ablative energy.

  • Spinal cord stimulator

    Implanted neuromodulation for refractory neuropathic pain after a successful trial. See our own guide for details.

  • Intrathecal drug pump

    Continuous intrathecal analgesia for refractory cases when oral therapy and neuromodulation are not enough.

  • MDT pain rehabilitation

    Physiotherapy, hydrotherapy, graded exercise, pacing and CBT delivered by a specialist multidisciplinary team.

A note on epidural steroid injections

Epidural steroid injections are widely used for other spinal pain conditions but are generally avoided in established arachnoiditis, as they can worsen inflammation and adhesions in some patients. Any interventional plan should be led by a specialist pain consultant familiar with the condition.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your pain consultant, neurologist or neurosurgeon knows your imaging and history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Neuropathic pain in adults: pharmacological management in non-specialist settings (CG173).

  • British Pain Society. Standards of good practice for spinal interventional pain procedures.

  • Royal College of Anaesthetists / Faculty of Pain Medicine. Core standards for pain management services in the UK.

  • Society of British Neurological Surgeons. Guidance on complex spinal pain and neuromodulation.

Red flags

When arachnoiditis needs urgent attention.

Most symptoms need planned specialist review. These are the situations that need same-day emergency care or urgent escalation.

  • Cauda equina syndrome

    New saddle anaesthesia, urinary retention, faecal incontinence or rapidly progressive leg weakness needs same-day emergency spinal MRI.

  • Suspected spinal infection

    Fever, back pain and neurological signs after any spinal procedure need urgent bloods, imaging and neurosurgical review.

  • Progressive weakness

    A new or worsening foot drop, or difficulty walking, is not typical background arachnoiditis pain and needs urgent reassessment.

  • Post-procedure deterioration

    Sudden severe pain or new deficit after epidural or intrathecal injection needs urgent review to exclude haematoma or infection.

  • Syrinx or hydrocephalus

    MRI evidence of a syrinx or hydrocephalus needs neurosurgical assessment for possible shunt or drainage.

  • Suicidal thoughts

    Severe chronic pain carries a real mental health burden. Low mood or suicidal thoughts need urgent GP or crisis support.

  • Opioid harm

    Sedation, confusion, breathing problems or escalating doses without benefit need urgent pain clinic and GP review.

  • Meningitis symptoms

    Fever, neck stiffness, headache and photophobia after any spinal or epidural procedure needs same-day emergency care.

  • Post-SAH deterioration

    New spinal or neurological symptoms after subarachnoid haemorrhage warrant urgent neurology and neurosurgery review.

Living with it

A long-term condition, with a coordinated plan.

Four things that make the biggest difference day to day. Pacing activity, gentle movement, mental health support and a coordinated specialist team.

A quiet reminder

Small, steady gains beat heroic effort.

Arachnoiditis rarely disappears, but function, mood and quality of life can improve steadily with the right MDT plan and a supportive charity network.

  1. 01 Pacing

    Work with the pain, not through it

    Break the day into small, achievable blocks of activity and rest. Boom and bust cycles make everything worse.

  2. 02 Movement

    Gentle, regular movement

    Hydrotherapy, walking and stretching, guided by a specialist physiotherapist, protect function without provoking flares.

  3. 03 Mind

    Look after the mind as well

    CBT for chronic pain, mindfulness and peer support genuinely change how the nervous system processes pain.

  4. 04 Team

    Build a specialist team

    A named pain consultant, GP, physiotherapist and, when needed, neurosurgeon and psychologist work best as a coordinated MDT.

Frequently asked

Everything we get asked about arachnoiditis.

Quick answers on causes, MRI, neuropathic pain treatment and when surgery has a role.

  • What is arachnoiditis?

    Arachnoiditis is inflammation and scarring of the arachnoid membrane, one of the layers surrounding the spinal cord and nerve roots. In its adhesive form, the nerve roots clump together and tether to the sac, producing chronic neuropathic pain and neurological symptoms in the lower back, buttocks and legs.

  • What causes arachnoiditis?

    The main causes are spinal surgery, particularly multiple procedures or failed back surgery syndrome, infection such as bacterial meningitis, TB, syphilis, viral or parasitic infection and spinal abscess, chemical injury from intrathecal injections, subarachnoid haemorrhage and major spinal trauma.

  • Are epidural steroid injections a cause?

    This is debated. Older oil-based myelographic agents such as Pantopaque and contaminated steroid preparations are well recognised triggers. Modern epidural steroid injections are widely used, but they are generally avoided in established arachnoiditis because they can worsen symptoms in some patients.

  • How is arachnoiditis diagnosed?

    The key investigation is MRI of the spine, which can show nerve root clumping, the empty thecal sac sign, adhesions and any associated syrinx. Diagnosis also needs a careful neurological and pain assessment, exclusion of other causes such as disc disease and stenosis, and sometimes electromyography.

  • Why is more spinal surgery usually avoided?

    Further open surgery, laminectomy or adhesiolysis often produces more scar tissue and can worsen pain. Surgery is generally reserved for specific problems such as significant hydrocephalus, a symptomatic syrinx or an unrelated compressive lesion, and is only done in specialist neurosurgical centres.

  • What can actually help the pain?

    A combination approach works best. Neuropathic pain medication such as gabapentin, pregabalin, amitriptyline or duloxetine, selective interventional options like sacral pulsed radiofrequency, spinal cord stimulation or an intrathecal pump in refractory cases, and MDT pain rehabilitation with physiotherapy, hydrotherapy and CBT. Support from an arachnoiditis charity can also make a real difference.

Related content

Keep reading.

Pulse Healthcare concierge

Send us your enquiry

A concierge service for UK private healthcare. We match you with the best vetted clinics and consultants in our network - they then contact you directly.

So we can match you to the right clinician close to you.

We reply to every enquiry within 24 hours (Mon–Fri). Confidential - your details are never shared outside our vetted consultant network.

WhatsApp us Reply within 24h · Mon–Fri
Call