Adhesive Arachnoiditis 

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Adhesive Arachnoiditis – 7 Interesting Facts

  1. Arachnoiditis is a rare disease. It is a painful inflammatory condition of the pia mater and arachnoid mater meninges in the spinal cord and nerve roots with diverse underlying causes
  2. It is most commonly due to iatrogenic damage such as neurosurgical interventions (reported to account for 60% of cases) and spinal or epidural anesthesia
  3. Other causes include spinal infections, spinal cord trauma, blood in the cerebrospinal fluid following subarachnoid hemorrhage, and spinal malignancies
  4. Clinical presentation includes paralysis of legs or debilitating cramps/spasms, back pain, and nonspecific symptoms
  5. Magnetic resonance imaging (MRI) is the reference standard for diagnosis
  6. They may also be asymptomatic and incidentally found on imaging
  7. Management is primary symptom-focused; evidence is limited for any disease-directed management strategies

Description

  • arachnoiditis is a rare, painful inflammatory condition of the pia and arachnoid in the spinal cord and nerve roots with diverse underlying causes(1,3)
  • about 60% of cases are thought be sequelae of spinal surgery(3)
  • lumbar spine is most commonly affected (thought to be due to increasing iatrogenic etiology), but cervical or thoracic spine may also be affected (2, Clin Neurol Neurosurg 2020 May;192:105717)

Also Called

  • adhesive spinal arachnoiditis(2)
  • arachnoiditis ossificans(2)
  • calcific arachnoiditis(2)
  • chronic spinal meningitis(2)
  • lumbar adhesive arachnoiditis(2)
  • lumbosacral adhesive arachnoiditis(2)
  • meningitis serosa circumscripta spinalis(2)
  • spinal arachnoiditis(2)
  • spinal fibrosis(2)
  • spinal meningitides with radiculomyelopathy(2)

Definitions

  • meninges are 3 membranous layers surrounding central nervous system; 3 layers include
    • dura mater (“hard mother”) – outermost thick, collagenous layer attached to inside of skull
    • arachnoid mater (“arachne mother” referring to spider, named for spiderweb appearance) – middle thin, translucent layer; has a few layers of flattened cells
    • pia mater (“tender mother”) – innermost single-cell layer membrane adhering closely to brain
    • Reference – Genesis 2019 May;57(5):e23288full-text

Types

  • arachnoiditis ossificans (AO) – intrathecal bony metaplasia of large arachnoid segments encasing the spinal cord
    • unknown if AO develops independently from adhesive arachnoiditis or as a complication of arachnoiditis (or both)
    • causes of AO are similar to those of adhesive arachnoiditis, but also include bone-forming disorders such as hyperparathyroidism and heterotopic osseous metaplasia
    • Reference – AJR Am J Roentgenol 2017 Sep;209(3):648

Epidemiology

  • rare, true incidence is unknown and varies by criteria used(1,2)
  • reported incidence is about 25,000 cases annually
    • mostly reported in North and South America, Asia, and Europe (likely due to higher prevalence of spinal operations in these areas)
    • Reference – Arachnoiditis. Orphanet 2010 Mar.
  • 2 cases of families with multiple affected members have been reported(3)

Etiology and Pathogenesis

Causes

  • iatrogenic damage (most common cause) due to(1,2,3)
    • neurosurgical interventions (reported to account for 60% of cases)
    • spinal or epidural anesthesia
    • epidural injection of corticosteroids or other agents
    • use of oil-based contrast agents during myelography (use of this is rare)
    • ≥ 1 spinal tap
  • epidural blood patch is another potential cause (Headache 2021 Feb;61(2):244)
  • spinal infections, such as due to(1,2)
    • tuberculosis
    • syphilis
    • gonorrhea
    • other various bacteria
  • trauma to spinal cord(3)(1,2)
  • blood in cerebrospinal fluid following subarachnoid hemorrhage(2)
  • metastatic malignancies involving the meninges

Pathogenesis

  • pathogenic mechanism involves inflammatory fibrous invasion from arachnoid into pia(1,2)
    • pia-arachnoid becomes inflamed, leading to collagen strand growth between nerve roots and pia and arachnoid
    • dense collagen deposition follows, and nerve root swelling decreases
    • spinal nerve roots then become strongly adhered to each other and/or to thecal sac; ultimately nerve roots are encapsulated and undergo progressive atrophy due to lack of blood supply
  • healing during inflammatory process is particularly difficult due to(1,2)
    • lack of vasculature in arachnoid
    • constant cerebrospinal fluid circulation, which washes out scar tissue-preventing phagocytes and enzymes
  • arachnoiditis often occurs on dorsal spine, and typically adhesions are arranged peripherally(2)

History and Physical

Clinical Presentation

  • arachnoiditis ranges from asymptomatic (and incidentally found on imaging) to resulting in paralysis of legs or debilitating cramps/spasms(1,3)
  • back pain that increases with activity with or without accompanying leg symptoms (pain, paresthesia, or weakness) is typical, and a wide range of neurologic abnormalities have been reported(2)
  • arachnoiditis may present many years after suspected causative event(2)
  • signs and symptoms are nonspecific and may include(1,2,3)
    • painful radicular syndrome (characterized by burning pain in the distribution of ≥ 1 lumbosacral nerve roots [often referred to as “sciatica”] with positive Lasegue sign)
    • numbness
    • tingling
    • loss of temperature sensation
    • muscle cramps or spasms (may be debilitating)
    • tinnitus
    • hearing and vision problems
    • loss of balance
    • bladder, bowel and sexual function may be affected
    • hyporeflexia (decreased reflex response)
    • reduced lumbosacral spine mobility
    • paralysis of the legs
  • clinical presentations reported in 28 adults (mean age 61 years, 64.3% female sex, 53.6% Black) with lumbar arachnoiditis in retrospective cohort study
    • common suspected etiologies were postprocedural or operative in 42.8%, infection in 21.4%, cancer in 10.7%, unknown in 10.7%, or other in 7%
    • symptoms were
      • static in 53.6%
      • progressive in 39.3%
      • unknown due to loss to follow-up in 7%
    • symptom onset to time of magnetic resonance imaging evaluation was < 1 month in 32%, and > 1 month in 67.9%
    • radiculopathy in 64.3%
    • symptoms in multiple locations in 75%
    • pain in
      • both legs in 50%
      • 1 leg in 21.4%
      • back in 21.4%
      • neither legs nor back in 7%
    • motor/sensory disturbance
      • no motor or sensory symptoms in 46.4%
      • motor symptoms in 25%
      • sensory symptoms in 17.9%
      • both motor and sensory symptoms in 10.7%
    • sphincter dysfunction in 7%
    • Reference – Clin Neurol Neurosurg 2020 May;192:105717

Diagnosis

Making the Diagnosis

  • diagnosis is suspected based on painful radicular syndrome, reduced spinal mobility, and/or spinal nerve root or cord dysfunction plus history of likely causative event(1)
  • diagnosis confirmed by typical findings on magnetic resonance imaging(1,2)
  • radiologic features may not correlate with clinical features(2)

Differential Diagnosis

  • other spinal conditions such as
    • spinal stenosis(2)
    • lumbar disc disease(2)
    • other compressive lesion(2)
    • spinal infection(2)
  • neoplastic meningitis (Cancer Control 2017 Jan;24(1):9)
  • for presentations after surgery, differential diagnoses include(3)
    • dislodged disc fragment
    • intraspinal hematoma
    • failed back surgery syndrome (FBSS)

Testing Overview

  • magnetic resonance imaging is diagnostic
  • tests that are reported not to be useful for arachnoiditis include(2)
    • blood or other lab tests
    • electromyography or other neurophysiologic testing

Imaging Studies

  • magnetic resonance imaging (MRI) is diagnostic(1,2)
  • radiologic features may not correlate with clinical features(2)
  • spinal MRI (typically thoracolumbar region) with gadolinium contrast findings are variable and may include
    • arachnoid cysts
    • clumping of nerve roots
    • thickening and displacement of nerve roots
    • contrast enhancement of nerve roots
    • spinal cord swelling with T2 signal hyperintensity
    • arachnoid separations
    • spinal cord compression
    • atrophy of the spinal cord
    • syrinx formation
    • narrowing, shortening of thecal sac
    • adhesions tethering nerve roots peripherally leading to ‘empty sac’ appearance
    • soft tissue replacing subarachnoid space
  • myelography
    • was used in the past, but MRI is now the reference standard (Cureus 2023 Jan;15(1):e33697)
    • on myelography, arachnoiditis adhesions are typically arranged peripherally and have been described as looking like “bark of a tree”(2)
  • common imaging features in retrospective cohort study of 29 adults (mean age 65 years, 62% male sex) with symptomatic advanced chronic adhesive arachnoiditis (all adults had MRI, and 7 patients had computed tomography [CT] myelography)
    • “advanced” disease defined as any imaging evidence of advanced disease (initially defined as swollen spinal cord and intramedullary increased T2 signal, later expanded to include other signs)
    • most common suspected etiologies included trauma (10 patients), prior surgery (9 patients), and nontraumatic subarachnoid hemorrhage (7 patients)
    • imaging features in all patients
      • loculated cerebrospinal fluid collections (arachnoid cysts) in 23 patients (79%)
      • nerve root clumping, enhancement, and displacement in 15 patients (52%)
      • cord swelling with increased T2 signal in 12 patients (41%)
      • arachnoid septations in 11 patients (38%)
      • pial or dural enhancement in 8 patients (28%)
      • cord displacement or tethering in 8 patients (28%)
      • cord atrophy in 6 patients (21%)
      • syrinx in 5 patients (17%)
    • among 7 patients with data, most common CT myelography features included
      • partial or complete block in 5 patients
      • arachnoid septations in 4 patients
      • cord displacement or tethering, nerve root clumping or thickening, cord atrophy, and intrathecal calcification 3 patients each
    • among 16 patients with follow-up imaging (range 1 month to 11 years), findings included
      • no significant change in 7 patients (44%)
      • mild progression in 5 patients (31%)
      • significant progression in 1 patient (6%)
      • surgery after initial imaging with improvement in 3 patients (19%)
    • Reference – AJR Am J Roentgenol 2017 Sep;209(3):648
  • most MRI signs do not appear associated with clinical features in adults with lumbar arachnoiditis, but nerve root contour may be associated with motor/sensory symptoms and thickened nerve roots with radiculopathy (level 2 [mid-level] evidence)
    •  based on retrospective cohort study
    • 28 adults (mean age 61 years, 64.3% female sex, 53.6% Black) with lumbar arachnoiditis and MRI data available were reviewed for MRI and clinical features
    • 64.3% of patients had MRI with and without contrast (35.7% had without contrast only)
    • common suspected etiologies were postprocedural or operative in 42.8%, infection in 21.4%, cancer in 10.7%, unknown in 10.7%, or other in 7.1%
    • symptom onset to time of magnetic resonance imaging evaluation was < 1 month in 32%, and > 1 month in 67.9%
    • most common MRI features
      • adhesions in 89.3%
      • abnormal nerve root contour in 85.7%
      • confounding pathology also present in 78.6%, including
        • “other” (epidural abscess, laminectomy, spinal canal stenosis, discitis, or tumor) in 50%
        • degenerative disc disease in 25%
        • degenerative disc disease plus other in 3.6%
      • thickened nerve roots in 60.7%
      • multiple levels of spinal involvement in 53.6%
    • clinical features
      • pain in
        • both legs in 50%
        • 1 leg in 21.4%
        • back in 21.4%
        • neither legs nor back in 7%
      • motor/sensory disturbance
        • no motor or sensory symptoms in 46.4%
        • motor symptoms in 25%
        • sensory symptoms in 17.9%
        • both motor and sensory symptoms in 10.7%
      • sphincter dysfunction in 7%
      • radiculopathy in 64.3%
      • symptoms in multiple locations in 75%
    • MRI features associated with clinical presentation
      • nerve root contour associated with presence of motor/sensory symptoms (p < 0.05)
      • thickened nerve roots associated with radiculopathy (p = 0.05)
      • nodular nerve roots and thickened nerve roots each associated with postoperative etiology (p = 0.01 each)
      • confounding lumbar pathologies associated with progressive symptom dynamics (p = 0.004)
    • no other significant associations between MRI findings and clinical features
    • Reference – Clin Neurol Neurosurg 2020 May;192:105717

Management

  • limited evidence for management, and evidence is from case reports and series(1,3)
  • no current treatment is specific to arachnoiditis, and interventions are aimed at relieving pain and improving symptoms that impair function; options include(1,3)
    • nonspecific pain management; see also Chronic Low Back Pain
    • physical therapy
    • psychotherapy; see also Counseling and Education for Chronic Low Back Pain
  • surgery (arachnoid dissection with duroplasty) is controversial due to generally only short-term relief and possibility of scar tissue generation (and condition recurrence or worsening)(1,3)
  • reported treatment outcomes in 24 case reports or series of 34 patients (age range 22-73 years) with spinal adhesive arachnoiditis following spinal subarachnoid hemorrhage
    • 31 patients received surgical interventions (laminectomy in 25 patients, micro adhesiolysis in 22, and shunt placement in 17, hemilaminectomy in 3, and laminoplasty in 1 patient [some patients received multiple interventions]); outcomes among these patients:
      • symptom improvement and asymptomatic outcome in 9 patients (29%)
      • partial improvement in 11 patients (35.5%)
      • stabilization in 4 patients (12.9%)
      • progressive worsening or no improvement in 7 patients (22.6%)
    • 4 patients were managed conservatively, of these
      • improvement in 1 patient
      • partial improvement in 2 patients
      • progressive worsening in 1 patient
    • Reference – Neurochirurgie 2018 Jun;64(3):177
  • permanent ventriculoperitoneal shunt has been reported in a case report, but evidence is limited and clinical implications are unclear (Clin Neurol Neurosurg 2020 Jul;194:105835)
  • immunosuppressive therapies reported to be ineffective in 3 of 4 adults with chronic spinal adhesive arachnoiditis in case series (eNeurologicalSci 2021 Sep;24:100350full-text); therapies included high-dose IV steroids in all 4 patients, methotrexate in 2 patients, and plasmapheresis in 1 patient
  • arachnoiditis ossificans
    • arachnoiditis ossificans is an intrathecal bony metaplasia of large arachnoid segments encasing the spinal cord thought to develop from chronic adhesive arachnoiditis (AJR Am J Roentgenol 2017 Sep;209(3):648)
    • laminectomy reported to improve symptomatic arachnoiditis ossificans at 5-25 months in 3 adults
      •  based on retrospective case series
      • 5 adults aged 43-73 years with arachnoiditis ossificans were review for interventions
      • 2 adults were asymptomatic and were unchanged at follow-ups of 16 and 25 months (1 patients received observation, 1 patient received corpectomy and fusion for osteomyelitis)
      • symptoms improved in 3 symptomatic patients who received laminectomy with or without adjunctive procedures at follow-up ranging from 5 to 25 months
      • Reference – Clin Neurol Neurosurg 2014 Sep;124:16

Complications

  • complications may include(1,2,3)
    • chronic pain (back and/or leg)
    • sensory dysfunction (loss of temperature sensation, tingling, and others)
    • motor dysfunction
    • loss of bladder and/or bowel control
    • sexual dysfunction
    • irreversible disability including leg paralysis
  • adhesive arachnoiditis is thought to potentially lead to arachnoiditis ossificans (AO), which is intrathecal bony metaplasia of large arachnoid segments encasing the spinal cord; AO may lead to

Prognosis

  • prognosis is unpredictable but typically arachnoiditis is associated with persistent pain and neurologic deficits(1,2,3)
    • disease is reported to
      • remain static in 50%-59% of cases
      • progress in 1.8%-33% of cases
    • arachnoiditis typically does not improve significantly with treatment
    • rarely, disease is mild and does not worsen, or may quickly progress to severe neurologic deficits and paralysis
  • symptom improvement or resolution reported after symptomatic interventions in 4 of 8 cases of arachnoiditis following epidural blood patch (level 3 [lacking direct] evidence)
    •  based on systematic review of case reports
    • systematic review of 8 patients with postepidural blood patch arachnoiditis (including 1 case report from the authors of the systematic review)
    • in case report from authors, symptomatic lumbar arachnoiditis discovered on imaging in 30-year-old female patient 14 days after receiving fourth epidural blood patch for recurrent headaches
      • interventions included methylprednisolone IV 1,000 mg at 100 mL/hour followed by prednisone 80 mg orally tapered over 12 days
      • at 1-month follow-up pain was dramatically improved, headaches were less frequent, and lower extremity motor strength was improved; patient was maintained on gabapentin 800 mg 3 times daily
    • in systematic review of 7 cases (age range 24-40 years; 6 female patients and 1 male patient) of arachnoiditis due to epidural blood patch
      • outcomes included persistent pain and/or disability in 3 cases (at 6-month to 3-year follow-up), improvement but persistent discomfort in 1 case (at 1 month), resolution in 2 cases (at 24 hours and 4 weeks), and unreported outcome in 1 case
      • interventions in unresolved cases included anti-inflammatory drugs, phenytoin, corticosteroids, physical therapy, and S1 nerve root blocks
      • interventions in improved or resolved cases included acetaminophen, nonsteroidal anti-inflammatory drugs, oxycodone, antibiotics IV for 14 days, and oral analgesic (type not reported)
    • Reference – Headache 2021 Feb;61(2):244
  • static disease or mild progression reported in 12 of 16 adults with symptomatic advanced chronic adhesive arachnoiditis at follow-up range of 1 month to 1 year
    •  based on retrospective cohort study
    • 29 adults (mean age 65 years, 62% male sex) with symptomatic advanced chronic adhesive arachnoiditis had imaging features reviewed (all adults had magnetic resonance imaging [MRI], and 7 patients had computed tomography [CT] myelography)
    • “advanced” disease defined as any imaging evidence of advanced disease (initially defined as swollen spinal cord and intramedullary increased T2 signal, later expanded to include other signs)
    • most common suspected etiologies included trauma (10 patients), prior surgery (9 patients), and nontraumatic subarachnoid hemorrhage (7 patients)
    • among 16 patients with follow-up imaging (range 1 month to 11 years), findings included
      • no significant change in 7 patients (44%)
      • mild progression in 5 patients (31%)
      • significant progression in 1 patient (6%)
      • surgery after initial imaging with improvement in 3 patients (19%)
    • Reference – AJR Am J Roentgenol 2017 Sep;209(3):648
  • additional spinal pathologies associated with progressive symptoms in adults with lumbar arachnoiditis
    •  based on retrospective cohort study
    • 28 adults (mean age 61 years, 64.3% female sex, 53.6% Black) with lumbar arachnoiditis and MRI data available were reviewed for MRI and clinical features
    • 64.3% of patients had MRI with and without contrast (35.7% had without contrast only)
    • common suspected etiologies were postprocedural or operative in 42.8%, infection in 21.4%, cancer in 10.7%, unknown in 10.7%, or other in 7.1%
    • symptom onset to time of magnetic resonance imaging evaluation was < 1 month in 32%, and > 1 month in 67.9%
    • symptoms were
      • static in 53.6%
      • progressive in 39.3%
      • of unknown course due to loss to follow-up in 7%
    • most common MRI features
      • confounding pathology also present in 78.6%, including
        • “other” (epidural abscess, laminectomy, spinal canal stenosis, discitis, or tumor) in 50%
        • degenerative disc disease in 25%
        • degenerative disc disease plus other in 3.6%
      • adhesions in 89.3%
      • abnormal nerve root contour in 85.7%
      • thickened nerve roots in 60.7%
      • multiple levels of spinal involvement in 53.6%
    • confounding lumbar pathologies associated with progressive symptom dynamics (p = 0.004)
    • Reference – Clin Neurol Neurosurg 2020 May;192:105717

Prevention and Screening

  • not applicable

Guidelines and Resources

Guidelines

United Kingdom Guidelines

  • National Institute for Health and Care Excellence (NICE) interventional procedures guidance on therapeutic endoscopic division of epidural adhesions can be found at NICE 2010 Feb:IPG333

Review Articles

  •  to search MEDLINE for (Adhesive Arachnoiditis) with targeted search (Clinical Queries), click therapy, diagnosis, or prognosis

Patient Information

References

General References Used

  1. Jurga S, Szymańska-Adamcewicz O, Wierzchołowski W, et al. Spinal adhesive arachnoiditis: 3 case reports and review of literature. Acta Neurol Belg. 2021 Feb;121(1):47-53.
  2. Rice I, Wee MY, Thomson K. Obstetric epidurals and chronic adhesive arachnoiditis. Br J Anaesth. 2004 Jan;92(1):109-20full-text.
  3. Arachnoiditis. Genetic and Rare Disease Information Center (GARD) 2016 Aug 17.

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