Arachnoiditis ossificans: Clinical series and review of the literature

• Arachnoiditis ossificans is likely due to an inflammatory process and is often associated with prior surgery or dural violation.
• Treatment of arachnoiditis ossificans with laminectomy may provide adequate decompression without resection of the ossified meninges.
• Significant neurologic recovery is possible, but close follow-up of this patient population is necessary as new areas of ossification may occur.

ObjectiveOssification of the leptomeninges, or arachnoiditis ossificans (AO) of the spine resulting in neurologic decline is a rarely reported disease. To date, there are 72 cases in the literature. The natural history of the disease and the best management strategy for patients with this condition is unknown. A series of five cases is presented adding to the relative paucity of knowledge of this potentially debilitating disease.MethodsA retrospective review of five cases of patients with arachnoiditis ossificans from 2009 to 2013 was conducted. All cases were obtained from a single institution. The diagnosis was based upon computed tomography (CT) and magnetic resonance imaging (MRI) studies.ResultsAll five patients in the series were found have a history of prior spinal procedures. Three of the five patients had no history of intradural procedures or violation of the dura. Three of the patients underwent surgery to address neurologic deficits related to AO. Surgical intervention mainly consisted of decompression via laminectomy without resection of the intradural bony lesions. All patients improved neurologically postoperatively.ConclusionsArachnoiditis ossificans is a rare disease typically affecting the thoracolumbar spine. It may result in devastating neurological deficits. There is no consensus as to the appropriate treatment strategy and the surgical procedures can be technically demanding due to the tight adherence of the abnormal bone to neural structures. For those patients who exhibit no symptoms referable to the AO, close observation may be performed. However, once progressive neurologic deficits occur due to AO, decompression via laminectomy can be a successful strategy.