Spinal arachnoid calcifications

Abstract

Arachnoid calcifications have been imaged on axial-CT and MRI. These often clinically asymptomatic deposits have been attributed to trauma, myelography (particularly with the use of oil-based contrast), subarachnoid hemorrhage, and spinal anesthesia. This report describes calcified arachnoid plaques in an 86-year-old male cadaver located in the dorsal thoracic level. A laminectomy from C4 to the lumbo-sacral junction was performed and the dura mater was transected and pinned aside. Three plaques between T2-T3, 3 at T7, 2 at T9 were noted. Plaques were 1.0 mm in thickness and ranged from 0.5 cm to 1.0 cm in diameter. The spinal cord or nerve roots were not displaced. The plaques stained positively with Von Kossa and Alizarin Red S staining, confirming that the deposits included calcium phosphate and calcium. Arachnoid calcifications are an incidental finding in cadavers and typically do not compress the spinal cord or nerve roots. However such plaques may be precursors to spinal arachnoid ossificans, a more serious condition that may cause spinal cord or nerve root compression.

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.…”

“…3 The underlying histopathology in AO is thought to be osseous metaplasia in the setting of chronic arachnoid inflammation leading to intrathecal ossification. 9,10 However, despite chronic adhesive arachnoiditis being easily seen on MR imaging, arachnoid ossification can be inconspicuous and may, therefore, be overlooked or misdiagnosed. Although AO is a rare entity, it is likely more widespread than previously thought.…”

A Case of Cauda Equina Arachnoiditis Ossificans and Review the Literature

“…Arachnoid calcification or ossification is a common phenomenon in surgery and autopsy [2][3][4]. These deposits are considered to be calcium crystals produced by degenerative processes, not real bone tissue, and they are not considered to cause clinically significant symptoms [5].…”

A Case of Lumbosacral Arachnoiditis Ossificans

“…Although the cause of arachnoiditis ossificans remains unclear, it is presumed that chronic inflammation in the dura mater or an increase in proliferative activity of arachnoidal and osteoblastic cells due to multiple factors causes bony metaplasia of the arachnoid membrane. 9) Furthermore, multiple factors such as systemic metabolism or hormones may be involved. 10) We presume the following onset mechanism of symptoms in our patient; since there were no distinct antecedent triggers such as spinal puncture, and the patient had a high urination and stool frequency from childhood, he had an acquired predisposition for ossification within the dura mater since childhood.…”