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.
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.
- haematogenous spread of systemic tumours
- direct seeding of the CSF from primary central nervous system tumours
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.
Treatment and prognosis
No treatment is available for adhesive arachnoiditis.
- 1. Ross JS, Masaryk TJ, Modic MT et-al. MR imaging of lumbar arachnoiditis. AJR Am J Roentgenol. 1987;149 (5): 1025-32. doi:10.2214/ajr.149.5.1025 - Pubmed citation
- 2. Morisako H, Takami T, Yamagata T et-al. Focal adhesive arachnoiditis of the spinal cord: Imaging diagnosis and surgical resolution. J Craniovertebr Junction Spine. 2010;1 (2): 100-6. doi:10.4103/0974-8237.77673 - Free text at pubmed - Pubmed citation
- 3. Medico-legal radiology. Churchill Livingstone. ISBN:0729538311. Read it at Google Books - Find it at Amazon
- 4. Castillo M. Neuroradiology Companion: Methods, Guidelines, and Imaging Fundamentals. LWW. ISBN:1451111754. Read it at Google Books - Find it at Amazon