Intradural extramedullary cavernous malformation with extensive superficial siderosis of the neuraxis: Case report and review of literature.

BACKGROUND: Spinal cavernous malformations usually affect the vertebral bodies and are seldom intradural. Here, we report a rare spinal intradural-extramedullary cavernous malformation associated with extensive superficial siderosis along the neuraxis in a patient with radicular complaints. CASE DESCRIPTION: A 60-year-old male presented with subacute headaches, intermittent fever, and acute back and radicular leg pain for 1-2 weeks. Magnetic resonance imaging revealed an intradural-extramedullary lesion just below the conus medullaris (at the L2 level). There was associated subarachnoid hemorrhage in the lumbar cistern and superficial siderosis along the entire spinal neuraxis. Following surgical resection, the patient's symptoms resolved. Histopathology of the lesion was of a cavernous malformation.
CONCLUSIONS: There are only 56 cases of spinal intradural-extramedullary cavernous malformations published in the literature; however, only 3 described superficial neuraxis siderosis as noted in this case. In the present case, slowly recurring hemorrhages of the lesion located at the conus likely contributed to the complete neuraxis superficial siderosis. Timely evaluation and treatment of these lesions is warranted to avoid further compressive and/or hemorrhagic complications.

INTRODUCTION

Spinal cavernous malformations (cavernomas or cavernous hemangiomas) are infrequent vascular malformations which occur primarily in the vertebral body, with or without extradural extension, that constitute 5–12% of all spinal vascular abnormalities.[11] Only 3% of spinal cavernomas are intradural, with intradural-extramedullary lesions being more rare compared with intramedullary locations.[8] Most patients present with symptoms related to spinal cord compression. Only 2 cases of intradural-extramedullary spinal cavernomas presented with superficial siderosis. Here, we report a cavernous malformation of the cauda equina presenting with extensive superficial siderosis extending from the brain and throughout the spinal neuraxis.

CASE REPORT

History and examination

A 60-year-old male with diffuse headaches and intermittent fever over several months presented with a 1–2-week history of left-sided low back pain radiating to the buttocks and the posterior aspect of the left leg. Other than radicular complaints, he had no focal neurological deficit. Laboratory findings were unremarkable. Magnetic resonance imaging (MRI) of the spine revealed a 1.8 × 1.3 × 1.1 cm intradural-extramedullary hemorrhagic lesion below the conus medullaris (at the L2 level) along with moderate subarachnoid hemorrhage (SAH) in the lumbar cistern and superficial siderosis along the conus [Figure 1]. MRI of the brain, cervical, and thoracic spine also identified diffuse superficial siderosis, a finding likely consistent with repeat hemorrhages [Figure 2].

Figure 1

Lumbar spine MRI demonstrating intradural-extramedullary spinal cavernous malformation. Sagittal T2-weighted (a), fat-suppressed gadolinium-enhanced T1-weighted (b), and T2 inversion recovery turbo-spin echo images show an intradural extramedullary lesion at L2. Hemosiderin deposition is seen along the conus (arrows), and fluid-subarachnoid blood level is layered in the lumbar cistern (arrowheads). Axial T2-weighted images (d-g) corresponding to scout levels on image (c) show the nerve root proximal to the lesion (d), followed by sections in the midst (e) and immediately below (f) the lesion. Layering of subarachnoid blood is well-appreciated on axial images (arrowheads in g)

Figure 2

Brain and cervicothoracic MRI demonstrating extensive superficial siderosis. Cervical (a) and thoracic (b) T2-weighted sagittal MRI images show superficial siderosis (arrows) across the cervical and thoracic spinal cord. Intracranial involvement (arrows) is seen in the cerebellum and along the brain stem on axial gradient-echo sequences (c-f)

Surgery

An L1-L2 laminectomy and durotomy were performed, and a large vascular lesion with numerous small blood-filled sacs consistent with cavernoma was identified. The lesion was readily separable from the surrounding nerve roots and was dissected out of the thecal sac [Figure 3]. As a clear margin could not be distinguished between the lesion and nerve roots and because direct stimulation of the proximal and distal nerve roots [Figure 3a and b] did not elicit any motor response on neuromonitoring, the lesion was removed en bloc [Figure 3c]. The patient's headaches and back pain rapidly resolved following surgery. Six months later, the patient was neurologically intact.

Figure 3

Intraoperative images during resection of spinal cavernous malformation. Stimulation of the proximal (a) and distal (b) ends of the involved nerve root (arrows) did not reveal any detectable motor function, and therefore the lesion was resected en bloc, along with the adjacent nerve root segments entering/exiting the lesion (c)

Histopathology

Histopathological examination revealed that the mass was an encapsulated cavernous malformation with acute and chronic hemorrhages and focal inflammation [Figure 4].

Figure 4

Sections showing a vascular lesion composed of tightly packed vascular channels with varying wall diameters and hyalinization. Vessel walls lacked any significant amount of smooth muscle or elastic tissue. Some vessel walls contained hemosiderin laden macrophages suggesting remote microhemorrhages. Scattered vessels showed thrombi at different stages of organization. These histologic features were consistent with a diagnosis of cavernous angioma. Intermediate power image (a) showing tightly packed vascular channels with vessels walls of varying diameters and some with hyalinization. Vessels walls lack elastic tissue and a significant amount of smooth muscle. High-power H and E image (b) of the cavernous angioma with entrapped nerve fibers. High-power image (c) of neurofilament staining the entrapped nerve fibers

DISCUSSION

There are 56 reports (including the present) of intradural-extramedullary spinal cavernous malformations [Table 1]. However, only 2 such cases with neuraxis siderosis have previously been reported;[3] this is the third such report.

Table 1

Published cases of spinal intradural extramedullary cavernous malformations*

Superficial siderosis of the central nervous system (CNS) is caused by recurrent hemorrhage into the subarachnoid space, with resultant hemosiderin deposition in the subpial layers of the brain and spinal cord. Extensive hemosiderin deposition can be seen along the surface of the neuraxis, especially along the cerebellum, brainstem, and lower cranial nerves; the triad of sensorineural hearing loss, cerebellar ataxia, and pyramidal tract symptoms reflects the common sites of involvement in this disease.[5] Spinal intradural-extramedullary cavernomas are very rarely a cause of superficial siderosis. Nevertheless, our case, along with the 2 previously reported cases,[3] suggest that intradural-extramedullary cavernous malformations of the lower spine can indeed lead to intracranial superficial siderosis, warranting consideration of such lesions as part of the differential diagnosis and prompting neuraxial imaging in these patients.

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Conflicts of interest

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