Symptomatic interdural cerebrospinal fluid collections after surgery for idiopathic spinal cord herniation: illustrative case

BACKGROUND Idiopathic spinal cord herniation (ISCH) is very rare. Some reports have described postoperative ventral cerebrospinal fluid (CSF) collections in patients with ISCH; however, such collections are asymptomatic in most patients, and there is no consensus regarding whether they are part of the natural history or a complication. OBSERVATIONS A 30-year-old man with ISCH underwent direct closure of a duplicated dura mater. Eight months postoperatively, he developed reworsening of right lower limb paresis and new severe right arm pain and paresis. Three-dimensional magnetic resonance imaging revealed ventral CSF collections, which the authors judged as the responsible lesions. The authors initially considered these collections to be present in the epidural space, extradurally compressing the dural sac and resulting in myelopathy. An epidural blood patch failed; however, a CSF drainage test resulted in dramatic improvement. The authors therefore determined that the CSF collections were located in the interdural space, not the epidural space. A lumboperitoneal (LP) shunt was performed to reduce the CSF pressure. The patient’s symptoms improved immediately postoperatively. He had developed no recurrence of symptoms 6 months after surgery. LESSONS Ventral interdural CSF collections after ISCH surgery can cause reworsening of myelopathy and may be cured by a LP shunt to control CSF pressure.

Thoracic ventral spinal cord herniation with progressive myelopathy – A case report and review of the literature

Background: Idiopathic spinal cord herniation (ISCH) is a rare, underrecognized, and often misdiagnosed entity of unclear pathogenesis that typically presents as a slowly progressive thoracic myelopathy. There are less than 200 such cases reported in the literature. ISCH diagnosis and treatment are often delayed contributing to greater fixed neurological deficits, often leading to costly, unnecessary imaging studies, and inappropriate surgery. Case Description: Here, a 48-year-old female presented with trauma-induced ISCH characterized by gradually worsening lower extremity myelopathy. Conclusion: Idiopathic spinal cord herniation (ISCH) is rare, often underdiagnosed posttraumatic myelopathy that, when accurately diagnosed and treated, can result in good outcomes.

Imaging Findings in Dorsal Thoracic Arachnoid Web and the Differential Diagnosis of “Scalpel Sign”

A dorsal thoracic arachnoid web represents an intradural extramedullary transverse band of arachnoid tissue that causes mass effect and dorsal cord indentation, and can or cannot be associated with spinal cord altered signal. On sagittal MR imaging, this focal dorsal indentation of the thoracic spinal cord resembles a scalpel with its blade pointing posteriorly (called a “scalpel sign”). Although very suggestive of dorsal thoracic arachnoid web, this sign is not specific and should be differentiated from other ventral cord displacement causes (eg, idiopathic spinal cord herniation and spinal arachnoid cyst). In idiopathic spinal cord herniation, cord tissue protrudes through a ventral dural defect, and the focal deformity can be seen along the ventral aspect of the cord on spinal axial MR imaging and with a characteristic “C sign” on sagittal MR imaging; in spinal arachnoid cysts, the marginated walls and the presence of smooth, wide scalloping of the cord surface can be identified. Recognition of these imaging findings, especially the scalpel sign, can help radiologists and clinicians make a correct diagnosis of ventral cord displacement causes and allow subsequent prompt treatment for the patient.