What is Arachnoiditis

Arachnoiditis is a serious neurological condition in which the arachnoid layer, one of the protective membranes surrounding the spinal cord and nerve roots, becomes chronically inflamed. This inflammation can lead to scarring (fibrosis) and adhesions, causing nerve roots to become compressed. This often causes severe nerve pain, neurological symptoms, and functional limitations.

There are roughly two forms:

Adhesive Arachnoiditis (AA)

In this form, scars and adhesions form between nerve roots and the arachnoid layer. As a result, the nerves can no longer lie freely or function, leading to progressive symptoms.

Common symptoms:

  • Chronic, burning, or stabbing nerve pain (often in the back, legs, or arms)
  • Loss of strength and sensory disturbances
  • Difficulty standing, walking, or sitting for long periods
  • Bladder and bowel problems
  • Muscle spasms or cramps
  • Sensations of water droplets or insects on the skin
  • Blurred vision, tinnitus
  • Fatigue and instability

Non-Adhesive Arachnoiditis

In this form, there is inflammation, but without clear adhesions or scarring on imaging. The symptoms can closely resemble those of AA, but the damage is less visible. Nevertheless, the impact on daily functioning is often significant.

Common symptoms:

Chronic back pain and radiating nerve pain
Tingling, burning sensation, or loss of sensation
Weakness or temporary "numbness" in the legs
Fatigue and overstimulation
Sometimes also bladder or bowel problems
Important to know:

The experience with arachnoiditis varies from person to person. Not everyone experiences the same symptoms or symptoms of the same severity. The impact depends on the location, extent, and degree of inflammation or adhesion. A correct diagnosis and guidance are essential.

Clinical stages of Arachnoiditis

Arachnoiditis (particularly the adhesive form, AA) can present in various ways and with varying degrees of severity. We generally distinguish four stages. (1) Mild, (2) Moderate, (3) Severe (4) Catastrophic. Each stage is associated with specific physical limitations, symptoms, and treatment needs. The earlier the condition is recognized, the greater the chance of recovery or stabilization, especially in the milder stages.

Stage 1 - Mild:

  • Pain, but no clear neurological deficits yet
  • Normal mobility
  • No bladder or bowel problems
  • No or mild need for pain medication

Stage 2 - Moderate:

  • Increase in pain and first signs of nerve damage
  • Difficulty standing, walking, or sitting
  • Possibly mild bladder/bowel problems
  • Requires regular medication (such as NSAIDs, neuropathic painkillers)

Stage 3 - Severe:

  • Severe nerve pain and muscle weakness
  • Problems with urination or incontinence
  • Alternating stool consistency (constipation or overflow diarrhea)
  • Loss of mobility (use of walker or wheelchair)
  • Medication dependency, often opiates and complementary therapies
  • Cognitive complaints such as brain fog and overstimulation

Stage 4 - Catastrophic:

  • Extensive neurological damage
  • Severe autonomic dysfunction
  • Complete dependence on assistive devices or bedriddenness
  • Severe pain management and extensive care needs

Side note: Other symptoms may also occur, such as headache, blurred vision, dizziness, ringing in the ears (tinnitus), or a runny nose.
MRI images do not always reflect the severity of the symptoms. However, in severe cases, adhesions, scarring, or deformities of the spinal canal are sometimes seen.

These phases can overlap. The best chances of recovery lie in the mild and moderate phases. All the more reason to diagnose and treat in a timely manner.

Causes of Arachnoiditis

Arachnoiditis is caused by damage or an inflammatory reaction in the arachnoid layer, the membrane that surrounds the spinal cord and nerve roots. This can lead to adhesions, scarring, and nerve damage.

Known causes include:

  • Spinal surgery
    For example, herniated disc surgery or other procedures involving access to the spinal cord.
  • Spinal taps or spinal injections
    Such as for anesthesia, pain management, or diagnostic examinations.
  • Infections
    Bacterial or viral infections in or around the spine.
  • Trauma
    Severe injury to the back or spine can cause inflammation and scarring.
  • Bleeding around the spinal cord
    For example, following an accident or a complication during a medical procedure.
  • Chemical irritation
    Substances used in injections or imaging (contrast agents) can cause irritation.
  • Chronic compression
    Prolonged pressure on the spinal cord or nerve roots, for example due to a severe herniated disc or a narrowed spinal canal (spinal stenosis).

Important to know:
Not everyone with one of these risk factors develops arachnoiditis. Often, multiple factors play a role, such as personal susceptibility and chance.

Related conditions

Arachnoiditis is a chronic inflammation of the arachnoid layer surrounding the nerve roots in the spinal cord. The condition is often associated with severe nerve pain, sensory disturbances, and loss of function. However, the impact often extends beyond the nervous system alone.

Many patients also develop Tarlov cysts (nerve root cysts) or disturbances in the circulation of cerebrospinal fluid (CSF). These can cause symptoms on their own, but can also contribute to the severity of arachnoiditis or delay recovery.

CSF Disruption and Leakage

CSF normally flows freely through the subarachnoid space, surrounding the brain and spinal cord. This flow can be disrupted by inflammation, adhesions, or cysts. Sometimes a CSF leak even develops, which can lead to symptoms such as:

  • Orthostatic headache (worsens when sitting or standing)
  • Dizziness, blurred vision
  • Nausea, a feeling of pressure in the head or neck
  • Concentration problems, 'brain fog'

Disruptions in CSF flow or leakage often also result in fluctuating pressure on nerves, which exacerbates symptoms.

Tarlov cysts

Tarlov cysts are fluid-filled sacs that form in the nerve roots, usually at the bottom of the spine (sacral region). In some people, they remain unnoticed, but in others, they cause symptoms such as:

  • Pain in the lower back, pelvis, or legs
  • Bladder and bowel disorders
  • Sensory disturbances or nerve pain
  • Worsening with increased pressure (coughing, straining)

Tarlov cysts can also contribute to arachnoid irritation or nerve compression.

Disrupted immune balance and systemic complaints

Prolonged inflammation, such as in arachnoiditis, can throw the immune system off balance. This sometimes leads to symptoms that resemble or overlap with autoimmune disorders and hormonal imbalances. Many patients report:

  • Chronic fatigue (ME/CFS-like presentation)
  • Hashimoto's (thyroid problems)
  • Rheumatism-like joint complaints
  • Hormonal dysregulation, such as adrenal exhaustion
  • Brain fog, sleep problems, skin complaints

These complaints are not always directly caused by arachnoiditis or CSF problems, but can be related to them or exacerbated by dysregulation in the nervous system and immune system.

Pay attention to your body

Do you recognize several of these symptoms? Then it is important to discuss them with your doctor. Early recognition of underlying causes, such as a CSF leak or cyst, can contribute to better symptom management and a better quality of life.