Diffuse arachnoid ossification and multiple arachnoid cysts presenting with progressive thoracic myelopathy

Imaging Appearance of Advanced Chronic Adhesive Arachnoiditis: A Retrospective Review

OBJECTIVE

Chronic adhesive arachnoiditis (CAA) is rare and has potentially devastating clinical consequences. The objective of this article is to review the clinical features of CAA and describe its appearance on imaging, to increase radiologists' awareness of this challenging diagnosis.

MATERIALS AND METHODS

Twenty-nine cases of advanced CAA seen at our institution over 18 years (1995-2013) were retrospectively reviewed. Chart review was performed, with attention given to data on clinical presentation, suspected cause, and interventions performed. All patients underwent MRI, and seven patients also underwent CT myelography. Clinical and imaging features were evaluated and categorized.

RESULTS

The 29 patients ranged in age from 23 to 96 years and included 11 women and 18 men. Suspected underlying causative factors included trauma (n = 10), prior surgery (n = 9), nontraumatic subarachnoid hemorrhage (n = 7), infection (n = 3), myelography with iophendylate used as contrast medium (n = 1), Guillain-Barré syndrome (n = 1), ankylosing spondylitis (n = 1), and unknown causes (n = 1). Imaging characteristics include loculated CSF collections (n = 23), nerve root clumping, enhancement, and displacement (n = 15), cord swelling with increased T2 signal (n = 12), arachnoid septations (n = 11), cord atrophy (n = 6), syrinx (n = 5), and intrathecal calcifications (n = 3). Ten patients underwent surgical procedures, and most had only brief clinical improvement.

CONCLUSION

CAA is a rare cause of devastating neurologic symptoms and chronic pain. The imaging features of CAA range from subtle to severe. Advanced arachnoiditis can present with spinal cord swelling and syrinx formation, which can mimic other disease processes. Inclusion of advanced CAA in the differential diagnosis can prevent unnecessary interventions.

Surgical manifestations of thoracic arachnoid pathology: series of 28 cases

Object

Various pathologies involving the thoracic arachnoid mater uniformly manifest as thoracic myelopathy and may present a significant management dilemma. The authors undertook this study to assess outcome in cases of thoracic myelopathy due to thoracic arachnoid pathology.

Methods

The authors have cared for and followed 28 patients with thoracic myelopathy from thoracic arachnoid pathology over the last 17 years. A chart review and contemporary follow-up of these patients was performed and outcomes were reported.

Results

Patients with thoracic myelopathy from thoracic arachnoid pathology often have improvement in their condition after surgical decompression/detethering procedures. While not universal, patients in this series had improvement in mJOA scores at 1 year after surgery (p = 0.0001) and at last follow-up (p = 0.04). Results indicated that across a wide variety of pathologies the extent of thoracic spinal cord involvement is a predictor of the disease course and outcome. Comparison of the group of patients with cord involvement limited to 2 vertebral segments (short-segment pathology) versus the group with cord tethering of more than 2 segments (long-segment pathology) showed that patients in the short-segment group more frequently had ventral or dorsal arachnoid bands (p = 0.003), more frequently had signal change in the cord on MRI (p = 0.02), and less frequently presented with a syrinx (p = 0.02), and a smaller percentage of patients in this group underwent reoperation (p = 0.02). While patients with short-segment pathology typically improved after a single operative intervention, patients with long-segment pathology typically improved after multiple operations, frequently for CSF diversion.

Conclusions

Thoracic arachnoid pathology causing thoracic cord dysfunction and myelopathy is varied, has multiple etiologies, and can be difficult to treat over the long term. Surgical management, when indicated, is case specific. Serial long-term follow-up is essential to document enduring clinical and radiographic success.

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

OBJECTIVE

To present a rare case of multiple compressive thoracic intradural cysts with pathologic arachnoid ossification, review the literature and present the surgical options. 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.