Arachnoid ossificans containing metaplastic hematopoietic marrow resulting in diffuse thoracic intrathecal cysts and severe myelopathy

Abstract

Objective To present a rare case of multiple compressive thoracic intradural cysts with pathologic arachnoid ossification, review the literature and present the surgical options. Summary of background data Few reports have identified the existence of arachnoid calcifications and intrathecal cysts causing progressive myelopathy. The literature regarding each of these pathologies is limited to case reports. Their clinical significance is not well studied, although known to cause neurologic sequelae. Methods An 81-year-old female clinically presents with rapidly progressive myelopathy. Pre-operative magnetic resonance imaging identified multiple compressive thoracic intrathecal cysts. Surgical exploration and decompression of these cysts identified calcified plaques within the arachnoid. Histopathologic examination revealed fibrocalcific tissue undergoing ossification with bone marrow elements. Results Due to progressive myelopathy, the thoracic cysts were decompressed and calcified plaques were excised, once identified intra-operatively. Conclusions On last examination, the patient's neurologic status had not improved, but had stabilized. The rate of neurologic improvement from excision and decompression is variable, but it may still be warranted in the face of progressive neurologic deficits.

Patterns of Intrathecal Ossification in Arachnoiditis Ossificans: A Retrospective Case Series

“…Other etiologies included trauma, infection, spondyloarthropathy, intrathecal drug administration, and remote intrathecal contrast administration. The lumbar spine was the most common location for AO within the published case reports, with the second most common location reported in the thoracic spine; [6][7][8][9][13][14][15][16][17][18][19][20][21] no cases of cervical spine AO were reported. The most common clinical presentations were lower extremity weakness and back pain.…”

Arachnoiditis Ossificans – A Rare Cause of Progressive Myelopathy

“…The regions of arachnoid ossification can have a similar appearance to calcification on MRI, ranging from hypointense to intermediate in signal intensity on T1 and T2 sequences, as well as hemosiderin when hypointense. While the diagnosis may not be as clear on an MRI, it is essential to document the extent of neural involvement and to identify potential coexisting pathology such as syringomyelia or intrathecal cysts [ 7 , 8 ]. Occasionally, secondary imaging findings may be identified to suggest an underlying etiology, as was the case with our patient.…”

Incidental finding of arachnoiditis ossificans in the lumbar spine

“…Findings typically include irregular thickening and clumping of the cauda equina, and can range from hypointensity to intermediate intensity on T1 and T2 studies 4 . MRI is particularly helpful for identifying the extent of neural involvement and identify coexisting or potentially etiological pathology 6 . CT provides optimal visualization of AO due to its high sensitivity for calcification that results from the different attenuation coefficients of bone, soft tissue and cerebrospinal fluid 1 .…”

“… 4 MRI is particularly helpful for identifying the extent of neural involvement and identify coexisting or potentially etiological pathology. 6 CT provides optimal visualization of AO due to its high sensitivity for calcification that results from the different attenuation coefficients of bone, soft tissue and cerebrospinal fluid. 1 This imaging modality further defines the characteristics of the ossifications and allows them to be classified into the three sub‐types of AO.…”