Arachnoiditis: Symptoms, Types, Causes and Treatment

Arachnoiditis is a rare yet potentially debilitating condition affecting the arachnoid mater, one of the membranes surrounding the brain and spinal cord. Its complex nature, variety of causes, and widely varying symptoms make diagnosis and management particularly challenging. This article provides a comprehensive overview of the symptoms, types, causes, and current treatment options for arachnoiditis, synthesizing evidence-based information from recent research.

Symptoms of Arachnoiditis

Arachnoiditis often presents with a complex array of symptoms, which can vary widely from person to person. These symptoms primarily result from inflammation and scarring of the arachnoid mater, leading to nerve root entrapment and, in some cases, disruption of cerebrospinal fluid (CSF) flow. Because the condition can mimic other neurologic disorders, a high index of suspicion is necessary for early detection and effective management.

Symptom	Description	Prevalence/Pattern	Source(s)
Pain	Chronic, often severe, in back and limbs	Most common, especially lower limbs	1 4 5 7 9
Paresthesia	Tingling, numbness, or “pins and needles”	Frequently reported	1 7 9
Weakness	Muscle weakness, particularly in lower extremities	May progress to significant disability	1 7 9
Vision loss	Loss of vision, especially in optochiasmatic form	Devastating, often irreversible	3 14
Bladder/Bowel	Dysfunction, including incontinence	In some cases	7
Neurologic deficits	Motor and sensory loss, cauda equina syndrome	Variable, often progressive	6 7

Table 1: Key Symptoms

Pain and Sensory Disturbances

The hallmark symptom of arachnoiditis is chronic pain, often described as burning, stinging, or shooting in nature. The pain typically affects the lower back and radiates into the legs but can involve any area depending on the site of inflammation or scarring. Paresthesias—such as tingling, numbness, or a “pins and needles” sensation—are also frequently reported and can be severe enough to interfere with daily activities 1 7 9.

Motor Weakness and Neurologic Deficits

As the inflammatory process progresses, it can cause entrapment and damage of nerve roots. This can lead to muscle weakness, particularly in the lower limbs, and, in severe cases, to paralysis. Some patients develop specific neurologic syndromes like cauda equina or conus medullaris syndromes, resulting in profound sensory and motor loss 6 7.

Visual and Autonomic Symptoms

In rare but devastating cases, such as optochiasmatic arachnoiditis, vision loss can occur due to inflammation around the optic chiasm. Bladder and bowel dysfunction may also develop, particularly in cases where the lower spinal cord is affected 3 7 14.

Disease Progression and Variability

Symptoms may emerge suddenly or insidiously over months to years. They often worsen over time, and, in many cases, the initial symptom is pain, which gradually progresses to include sensory and motor deficits 1 4 7. The variability in presentation can easily lead to misdiagnosis or delayed treatment.

Types of Arachnoiditis

Arachnoiditis is not a uniform disease but rather a spectrum of disorders distinguished by their underlying cause, location, imaging features, and clinical behavior. Understanding these types is essential for accurate diagnosis and effective treatment planning.

Type	Location/Features	Distinguishing Aspects	Source(s)
Adhesive	Spinal, craniovertebral junction	Dense scarring, adhesions	1 4 7 12
Ossificans	Spinal (thoracic, lumbar)	Bone formation in arachnoid	2 7
Optochiasmatic	Basal brain regions	Visual loss; TB-related	3 14
Postinfectious	Spinal or cranial	Follows infection	5 13
Familial	Spinal	Familial clustering	1

Table 2: Types of Arachnoiditis

Adhesive Arachnoiditis

This is the most common and severe form, characterized by thickening and scarring (adhesions) of the arachnoid mater. These adhesions can trap nerve roots, leading to persistent pain and neurologic deficits. Adhesive arachnoiditis often follows spinal surgery, hemorrhage, trauma, or chronic inflammation 1 4 7 12.

Arachnoiditis Ossificans

A rare subtype, arachnoiditis ossificans involves pathological bone formation within the arachnoid membrane. It is classified into three types based on radiological appearance and location: semicircular (Type I), circular (Type II), and englobing caudal fibers (Type III). Treatment depends on location and severity, with some cases managed conservatively and others requiring surgery 2 7.

Optochiasmatic Arachnoiditis

This form predominantly affects the basal regions of the brain, particularly around the optic chiasm, often as a complication of tuberculous meningitis. It is associated with devastating vision loss and is more common in younger adults and women 3 14.

Postinfectious and Familial Forms

Arachnoiditis can develop after infections like meningitis (bacterial or tuberculous) or following familial patterns, though the latter is extremely rare. Postinfectious cases may manifest years after the initial infection, sometimes complicated by syringomyelia (fluid-filled cavities in the spinal cord) 1 5 13.

Causes of Arachnoiditis

The development of arachnoiditis is typically triggered by an insult to the arachnoid mater, leading to chronic inflammation and scarring. The causes can be broadly categorized into mechanical, chemical, infectious, and rarely, hereditary factors.

Cause Type	Example Triggers	Notable Details	Source(s)
Mechanical	Surgery, trauma, spinal puncture	Common following back surgeries	1 4 6 7 9
Chemical	Myelograms, steroids, neurotoxic agents	Oil-based contrast agents notable	6 7 8 9
Infectious	Bacterial, tubercular, viral meningitis	Postinfectious inflammation	3 5 13 14
Hemorrhagic	Subarachnoid hemorrhage, aneurysm rupture	Leads to CSF flow disruption	4 5
Iatrogenic	Intrathecal drugs, anesthetics	Steroid-induced, novel therapies	8 9
Hereditary	Familial clustering	Extremely rare, familial cases	1

Table 3: Main Causes of Arachnoiditis

Mechanical Causes

Spinal surgery, repeated lumbar punctures, and spinal trauma are leading mechanical triggers. These interventions can damage the arachnoid mater directly or introduce blood and other irritants into the subarachnoid space, initiating the inflammatory cascade 1 4 6 7 9.

Chemical and Iatrogenic Causes

Exposure to certain substances—such as oil-based contrast agents (formerly used in myelography), intrathecal steroid injections, or other neurotoxic drugs—can induce arachnoiditis. Iatrogenic cases, particularly from intrathecal therapies for other neurologic conditions, are increasingly recognized 6 7 8 9.

Infectious Causes

Both bacterial and tuberculous meningitis are well-documented causes. The inflammation can be acute or, as is often the case, result in chronic scarring and delayed symptom onset. Tuberculous optochiasmatic arachnoiditis is a particularly severe manifestation 3 5 13 14.

Hemorrhagic and Hereditary Causes

Subarachnoid hemorrhage, especially following aneurysm rupture, can disrupt CSF flow and precipitate arachnoid scarring. Familial cases, while extremely rare, highlight a possible genetic predisposition in select populations 1 4 5.

Treatment of Arachnoiditis

Managing arachnoiditis remains a major clinical challenge due to its chronic, progressive nature and the lack of a definitive cure. Treatment strategies are highly individualized, aiming to alleviate symptoms, address underlying causes, and prevent further neurological decline.

Treatment	Approach/Goal	Efficacy/Notes	Source(s)
Symptom control	Analgesics, anti-inflammatories	Mainstay for chronic pain	7 9 12
Steroids	Reduce inflammation	Variable efficacy, often limited	3 12 14
Disease-specific	Antitubercular drugs, antiparasitics	Used for infectious cases	11 14
Surgery	Lysis of adhesions, shunt procedures	For CSF flow restoration, syrinx	2 4 13
Immunotherapy	Methotrexate, plasmapheresis	Limited evidence, early use better	12
Experimental	Hyaluronidase, hydrogel implants	Promising but unproven	10 14
Rehabilitation	Physical therapy	Supportive, improves function	9

Table 4: Treatment Options

Symptom Management

Pain control remains the cornerstone of therapy. A combination of analgesics (including opioids, as appropriate), nonsteroidal anti-inflammatory drugs (NSAIDs), and neuropathic pain agents (such as gabapentinoids) are commonly used. Rehabilitation and physical therapy are essential in maintaining mobility and function 7 9 12.

Anti-inflammatory and Immunomodulatory Therapies

Corticosteroids are frequently administered to reduce inflammation, particularly in acute or early-stage disease. However, their effectiveness is inconsistent, especially in chronic cases. Immunosuppressive agents like methotrexate and plasmapheresis have been tried, but with limited and variable success, especially if adhesions have already formed 3 12 14.

Treatment of Underlying Cause

In cases of infectious arachnoiditis, targeted antimicrobial therapy is essential. For example, antitubercular drugs are crucial in tuberculous arachnoiditis, sometimes combined with corticosteroids and, in select cases, adjuvant therapies like intrathecal hyaluronidase 11 14. In neurocysticercosis, antiparasitic treatment with praziquantel has been shown to provide some benefit 11.

Surgical Intervention

Surgery may be indicated for patients with severe neurological deficits, particularly those with syringomyelia or obstructed CSF flow. Procedures such as lysis of adhesions or shunt placement can offer symptomatic relief, although recurrence is not uncommon. The decision for surgery is highly individualized and based on the type and extent of disease 2 4 13.

Experimental and Novel Approaches

Research into novel therapies, such as bioengineered hydrogels that modulate inflammation and scarring, as well as intrathecal hyaluronidase, shows promise but remains investigational. Early intervention may be key to preventing the irreversible formation of adhesions 10 12 14.

Conclusion

Arachnoiditis is a complex, multifactorial condition characterized by chronic inflammation and scarring of the arachnoid mater, leading to a spectrum of neurological symptoms and complications. While the disease remains incurable, early recognition and a multidisciplinary approach to management can improve quality of life and functional outcomes for affected individuals.

Key Points Covered:

• Symptoms can range from chronic pain and sensory disturbances to severe neurologic deficits and vision loss.
• Types include adhesive, ossificans, optochiasmatic, postinfectious, and rare familial forms.
• Causes span mechanical, chemical, infectious, hemorrhagic, iatrogenic, and hereditary factors.
• Treatment focuses on symptom control, anti-inflammatory and disease-specific therapies, surgical interventions, and supportive rehabilitation, with ongoing research into novel approaches.

By understanding the diverse presentations and challenges of arachnoiditis, clinicians and patients can work together to optimize diagnosis, management, and ultimately, patient outcomes.