Dr Yair Glick and Radswiki et al.

Arachnoiditis is a broad term encompassing inflammation of the meninges and subarachnoid space.

Arachnoiditis affecting the cauda equina may be referred to as spinal/lumbar adhesive arachnoiditis

Lumbar spine arachnoiditis can result in leg pain, sensory changes and motor weakness.

In some individuals, CSF flow is impaired, and they may develop syringomyelia which should, therefore, be sought in the cord.

  • infectious
  • inflammatory
    • surgery
    • intrathecal haemorrhage
    • intrathecal compounds 
      • lipiodol-containing contrast media, e.g. iophendylate (PantopaqueTM/MyodilTM) - controversial 3
      • anesthetics
      • steroids (accidental intrathecal injection)

Leptomeningeal carcinomatosis can also lead to nerve root clumping although this is not strictly speaking inflammatory in nature. Nonetheless, it is sometimes included under the broader meaning of arachnoiditis and certainly can mimic run-of-the-mill arachnoiditis. 

All modalities will demonstrate similar findings although MRI is by far the most sensitive modality. Although arachnoiditis can be present throughout the subarachnoid space, it is most easily seen in the lumbar region where the cauda equina usually floats in ample CSF. In arachnoiditis the nerve roots are irregularly thickened and clumped together, often stuck to the dura, resulting in an empty thecal sac sign

Rarely ossification / dystrophic calcification occurs and this is known as arachnoiditis ossificans

No treatment is available for adhesive arachnoiditis. 

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Article information

rID: 12614
Tag: cases
Synonyms or Alternate Spellings:
  • Adhesive arachnoiditis
  • Arachnoiditis - general
  • Lumbar adhensive arachnoiditis

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Cases and figures

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    Case 1: with empty theca sign
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    Case 2: post operative
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    Case 3
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