Spinal ependymoma complicated by superficial siderosis

Abstract

DESCRIPTIONA 64-year-old woman presented with progressive hearing loss. A pure-tone audiography confirmed bilateral high-frequency sensorineural hearing loss. Her medical and surgical history was unremarkable except for long-standing back pain. Neurological examination revealed mild dysmetria and gait ataxia. There was no leg weakness or sphincteric dysfunction.MRI revealed superficial siderosis lining the cerebellum and brainstem, which prompted further imaging of the entire neuraxis in order to exclude an underlying cause. A myxopapillary ependymoma seen at the level of the conus medullaris was felt to be responsible for recurrent haemorrhage within the subarachnoid space.Excision of the spinal ependymoma was performed and the patient regained near-normal hearing following a cochlear implant. DISCUSSIONSuperficial siderosis presents with slowly progressive sensorineural hearing loss, gait ataxia and cerebellar dysarthria. Involvement of other cranial nerves has also been described. Clinical history and examination often suggest a neurodegenerative disorder.1 Superficial siderosis results from haemosiderin deposition in the subpial layers of the neuraxis, and complicates chronic haemorrhage within the subarachnoid space. The posterior fossa is preferentially affected, which may in part be explained by the presence of Bergmann glia in the cerebellum that display increased ferritin synthesis.2 The long glial segment of the vestibulocochlear nerve makes it more vulnerable to axonal damage by iron deposition.1 Bilateral sensorineural hearing loss is present in 95% of affected individuals.3 Figure 1 Linear hypointensity is seen along the cerebellar folia and superior vermis on the axial gradient echo images (A) compatible with extensive haemosiderin deposition. There is also hypointense lining of the midbrain tectum and pons. The sagittal T1-weighted image (B) reveals low signal intensity of the upper cerebellum due to extensive haemosiderin preferentially deposited in the upper cerebellum and superior vermis. The linear hypointensities are also appreciated on the axial T2 sequence (C) where they clearly outline the cerebellar folia and ventral pons and reflect the characteristic subpial haemosiderin deposition. Mild underlying cerebellar atrophy is also appreciated. The radiological findings are pathognomonic of superficial siderosis.

Superficial siderosis due to filum terminale tumor: An uncommon cause of cranial nerve dysfunction

“…Of note, SWI has not been previously reported in these cases (to our knowledge), and in only one other case was the siderosis not detectable on T2 imaging, as in our case . With removal of the tumor, the majority of symptoms resolved with the exception of sensorineural hearing loss, which remained stable consistent with previous cases . The persistence of the hearing loss is thought to be due to the particular susceptibility of the vestibulocochlear nerve to hemosiderosis and likely resulting early damage to the nerve itself …”

“…Despite the small number of spinal tumors seen in the largest case series, there have been a number of case reports of myxopapillary ependymomas causing superficial siderosis. 5,6,8,9 Of note, SWI has not been previously reported in these cases (to our knowledge), and in only one other case was the siderosis not detectable on T2 imaging, as in our case. 8 With removal of the tumor, the majority of symptoms resolved with the exception of sensorineural hearing loss, which remained stable consistent with previous cases.…”

“…A recent review of 65 cases of infratentorial superficial siderosis reported that there were no cases in which blooming artifact on gradient echo/SWI sequences was not associated with concurrent T2 hypointensity . This is also highlighted by multiple previous case studies . In our case, the T2 weighted imaging was normal and only the susceptibility weighted imaging (SWI) was able to demonstrate the extensive siderosis highlighting the importance of using blood‐sensitive sequences.…”

“…This highlights the importance of initial complete brain and spine MR imaging in the investigation of these cases; this was particularly true in our case, as the myxopapillary ependymoma seen was clinically silent. Despite the small number of spinal tumors seen in the largest case series, there have been a number of case reports of myxopapillary ependymomas causing superficial siderosis . Of note, SWI has not been previously reported in these cases (to our knowledge), and in only one other case was the siderosis not detectable on T2 imaging, as in our case .…”

“…4 This is also highlighted by multiple previous case studies. 5,6 In our case, the T2 weighted imaging was normal and only the susceptibility weighted imaging (SWI) was able to demonstrate the extensive siderosis highlighting the importance of using blood-sensitive sequences.…”