Arachnoiditis and back pain
Last reviewed: 23.04.2024
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Arachnoiditis is a thickening, scarring and inflammation of the arachnoid membrane. These changes may be local or lead to compression of the nerve roots and spinal cord. In addition to pain, patients can experience numbness, weakness, may show a decrease in reflexes, symptoms of bladder and bowel dysfunction. The exact cause of arachnoiditis is not known, but it can be associated with disc herniation, infection, tumor, myelography, spinal cord surgery, or intrathecal administration of drugs. There are cases of arachnoiditis after epidural or subarachnoidal administration of methylprednisolone.
[Symptoms of arachnoiditis
Patients with arachnoiditis complain of pain, numbness, tingling and paresthesia in the innervation zone of the affected nerve root or roots. There may be weakness and impaired coordination in the affected limb; often there are muscle spasms, back pain and pain radiating to the buttocks. At physical examination, a decrease in sensitivity, weakness, and change in reflexes are found. Sometimes in patients with arachnoiditis there is compression of the lumbar spinal cord, spinal roots and roots of the horse's tail, which leads to lumbar myelopathy or horse tail syndrome. These patients show weakness of varying degrees in the lower limb and symptoms of bladder and bowel dysfunction.
Examination
MRI gives the most complete information about the lumbar spine and its contents, it should be carried out to all patients with suspected arachnoiditis. MRI is highly informative and can identify a pathology that threatens the development of lumbar myelopathy. For patients who can not pass an MRI (presence of pacemakers), CT and myelography are a reasonable alternative. If a fracture or bone pathology is suspected, such as a metastatic disease, a radionuclide bone scan or an overview radiograph is indicated.
While MRI, CT and myelography provide useful neuroanatomical information, electromyography and study of nerve conduction velocity - neurophysiological data on the actual state of each nerve root and lumbar plexus. Electromyography can also distinguish between plexopathy and arachnoiditis, and identify the existing tunneling neuropathy that can complicate the diagnosis.
If the diagnosis is questionable, a laboratory examination should be conducted, including a general blood test, ESR, the determination of antinuclear antibodies, HLA B-27 antigen, and blood biochemistry to determine other causes of pain.
Differential diagnosis
Arachnoiditis is a clinical diagnosis, supported by a combination of anamnesis, physical examination, radiography and MRI. Conditions that can simulate arachnoiditis: a tumor, infectious diseases and pathology of the lumbar spine, roots, plexus and nerves.
Treatment of arachnoiditis
There is no consensus on the most effective treatment of arachnoiditis; the greatest efforts are directed to decompression of the nerve roots and spinal cord and treatment of the inflammatory component of the disease. Epidural neurolysis or caudal administration of steroids can reduce the compression of the roots at local pathology. Generalized arachnoiditis requires surgical laminectomy. The results of such treatment are at best disappointing. Sleep disorders caused by depression are best treated with tricyclic antidepressants, such as amitriptyline, which can be started with 12.5 mg once a day before bedtime. Neuropathic pain associated with arachnoiditis can respond to gabapentin. Stimulation of the spinal cord can also lead to a reduction in symptoms. Opioid analgesics should be used with caution, if at all.
Complications and Diagnostic Errors
Untimely diagnosis of arachnoiditis may increase the risk of lumbar myelopathy or horse tail syndrome, which, if untreated, may progress to paraparesis or paraplegia.