A brief summary about Arachnoiditis for busy physicians.

Brief Summary for 
Medical Professionals

Sarah Andreae-Jones MB BS (Smith)

Arachnoiditis is a chronic, insidious inflammatory condition that typically causes debilitating, intractable neurogenic back and limb pain and a range of other neurological problems. This condition is substantially under-diagnosed and adverse drug reactions under-reported, so that the true incidence has yet to be established. It remains an incurable condition at this time.

There are 2 main subtypes of arachnoiditis:

1.Mechanically-induced: which resembles epidural fibrosis, with localised pathology and symptoms.

2.Chemically-induced arachnoiditis, often iatrogenic, which results in a systemic, toxic type picture, and may be associated with autoimmune disorders.

 

CAUSES:
1. Of mechanically-induced arachnoiditis (MIA) Spinal surgery (especially multiple) Multiple lumbar punctures
Trauma Spinal stenosis (congenital/degenerative) Chronic disc prolapse/ degenerative disc disease

2.Of Chemically-induced arachnoiditis (CIA) Myelographic dyes (especially oil-based such as Myodil (Pantopaque)) Epidural steroid injections (e.g. Depo-Medrol) Epidural anaesthesia Other intraspinal drugs such as amphotericin B and methotrexate Chemonucleosis with chymopapain

3.Miscellaneous
Subarachnoid haemorrhage Infection e.g. meningitis

SYMPTOMS :
Predominant and most distressing symptom is chronic, persistent deafferentation pain (causalgia) in lower back and lower limbs. (this may also occur throughout the body) Often central pain, allodynia, dyesthesia, hyperpathia, in widepread distribution. Tends to be worse at night and pain felt in numb areas is pathognomonic of neurogenic pain. Sensory symptoms: parasthesiae, numbness, bizarre sensations. Loss of temperature sensation and proprioception. 

Motor: weakness, muscle cramps, spasms and fasciculation.

Autonomic: bladder/bowel/sexual dysfunction; hyperhidrosis/anhydrosis; heat intolerance; dysphagia (possibly with non-cardiogenic chest pain);limb oedema (c.f. RSD/CRPS); autonomic dysreflexia (c.f. spinal cord injury) Autoimmune type: intermittent low grade fever; raised ESR, lymphadenopathy, malaise, joint pains, skin rashes, dry eyes. New drug( and other) allergies. Miscellaneous: osteoporosis; weight gain; low potassium; dental problems; visual problems.

Side-effects of medication. Depression and anxiety: as in all chronic illnesses; exacerbated by sleep disturbance, experienced by most patients.

DIFFERENTIAL DIAGNOSIS:
Other types of failed back surgery syndrome e.g. epidural fibrosis, recurrent disc herniation etc. Also, arachnoiditis may mimic Multiple Sclerosis, Cauda Equina Syndrome, Systemic Lupus Erythematosus. Some patients are diagnosed with fibromyalgia, but these symptoms are likely to occur as a secondary feature due to the altered spinal dynamics. Often, patients are considered to have psychosomatic problems or may be diagnosed with Chronic Pain Syndrome, depression or even to be malingering for compensation purposes.

TREATMENT:
Generally speaking, this complex neurogenic pain syndrome is best treated at a specialist pain clinic, with a multidisciplinary approach. As it is a chronic, incurable condition, it is vital that a sustained multimodal approach is maintained: using medication, physical modalities (hydrotherapy, gentle exercise, massage, stretching), lifestyle measures (e.g. diet, smoking etc), psychological support (especially establishing a strong therapeutic alliance). 

Medication: of the well-established treatment regimes, opiates are frequently used, often as part of a triad with antidepressant at low dose(tricyclic group are best) and anticonvulsant such as tegretol/gabapentin. Risk of addiction to opiates is very small. Muscle relaxants such as baclofen may be necessary to combat painful muscle spasms. 

NSAIDS may be useful for musculoskeletal pain or during “flare-ups” Invasive treatments carry potential risk of exacerbating the condition, but patients who have not responded to oral treatment may require a spinal cord stimulator or intraspinal narcotic device (the pump). 

Epidural steroids are of little benefit and are implicated in causing arachnoiditis. 

Surgery is generally not effective in the long-term, due to recurrence.

Non pharmacological treatment such as hydrotherapy may be useful but arachnoiditis is essentially an inflammatory condition and physiotherapy must be tailored accordingly to prevent flare-ups (c.f. Rheumatoid
arthritis etc.).

Cognitive pain management techniques may be of some help, but will generally not be sufficient alone.

Dr. S. A. Andreae-Jones MB BS
October 2000.