ossifizierende Arachnoiditis

Arachnoiditis ossificans is considered a sequela of chronic arachnoiditis where there is a development of calcification-ossification of the arachnoid membrane usually of the thoracic and lumbar spines. It is an extremely rare cause of spinal canal stenosis and consequent neurological compromise.


Its exact etiology is uncertain although thought to be likely due osseous metaplasia associated with chronic inflammation. It is often associated with prior surgery or dural violation.

Radiographic features

It may be seen as areas of linear or mass-like intrathecal lesions .


Can be seen as calcification-ossification within the spinal canal.

  • T1: intrathecal ossification is hyperintense
  • T2: intrathecal ossification is hypointense

Treatment and prognosis

If progressive neurologic deficits occur, decompression via laminectomy may prove successful .

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