DOI: 10.1097/MAO.0b013e31816569dd
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PMID: 18401286
Issn Print: 1531-7129
Publication Date: 2009/01/01
Intralabyrinthine Hemorrhage Associated With Superficial Siderosis of the Central Nervous System
Carlos Toyama; Carlos Jorge da Silva; Flávio Túlio Braga; Rubens Brito
Excerpt
Sudden sensorineural hearing loss caused by intralabyrinthine hemorrhage is a rare entity reported in patients with coagulopathy, anticoagulant therapy, trauma, labyrinthitis, leukemia, cocaine consumption, systemic lupus erythematosus, and local hemorrhagic pathologies (1). Intralabyrinthine hemorrhage is probably an underdiagnosed condition that, before the advent of magnetic resonance imaging (MRI), had been described in the literature only after postmortem evaluation. Magnetic resonance imaging demonstrates intralabyrinthine hyperintensities on spin echo T1-weighted (T1 SE) images, consistent with either methemoglobin content from hemorrhage or elevated protein levels (Fig. 1). Persistent intralabyrinthine hyperintensities on fat-saturated T1-weighted images exclude the possibility of a lipoma. Superficial siderosis of the central nervous system (CNS) is a rare cause of sensorineural hearing loss secondary torecurrent low-grade subarachnoid hemorrhage. As time goes by, the hemorrhage leads to hemosiderin deposition in the subpial layer of the brain and spinal cord. The most common neurological manifestations include sensorineural hearing loss and ataxia. The chronic and recurrent low-grade subarachnoid hemorrhage is crucial to the development of superficial siderosis because the syndrome does not occur after a single bleeding. Additional features include pyramidal signs, bladder incontinence, anosmia, and other cranial nerve palsies. In the past, superficial siderosis could only be diagnosed by surgical inspection of the brain or by postmortem evaluation. Recently, the diagnosis of this syndrome has become available by MRI, which can easily demonstrate even small deposits of iron-containing pigments because of their marked paramagnetic properties. One can recognize superficial siderosis on spin echo T2-weighted, and mainly on gradient echo T2-weighted (T2*) sequences (Figs. 2 and 3) by the presence of marked hypointensities along leptomeningeal surfaces, particularly over the brainstem, cerebellum, vestibulocochlear nerves, and spinal cord secondary to the deposition of ferric ions (2). The superior cerebellar vermis is the most frequently and severely affected site. Several possible causes of CNS superficial siderosis have been described. Nearly half of the patients with this condition have no identifiable cause for the chronic or recurrent subarachnoid hemorrhage. Meningeal pathology is the most common cause, being responsible for 47% of cases. Tumors (ependymoma and, less commonly, meningioma, oligodendroglioma, pineocytoma, and paraganglioma) are responsible for 35% of cases; and vascular abnormalities (arteriovenous malformation, aneurysm, and cavernous angioma), for 18% of cases (3). The bleeding site is not always identifiable, despite the complete angiographic evaluation.
Intralabyrinthine hemorrhage and CNS superficial siderosis are differential diagnosis in patients with sudden and progressive bilateral sensorineural hearing loss, respectively. When this association is suspected, MRI permits a specific diagnosis in vivo.
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