Superficial siderosis of the central nervous system
Updates to Article Attributes
Superficial siderosis (SS) is a rare condition which results from deposition of haemosiderin along the leptomeninges, with eventual neurological dysfunction.
The literature is divided as to whether the term superficial siderosis should be confined to cases where there is no history of symptomatic subarachnoid haemorrhage, or whether it is a blanket term referring to the superficial deposition of haemosiderin, irrespective of cause.
For the purpose of this article, we take the later definition.
Epidemiology
As there are many causes of recurrent or extensive subarachnoid haemorrhage, the demographics are ill-defined and represent those of the underlying cause. Cases have been reported between 14 and 77 years of age 5. Causes include 1-6:
-
spinal dural defectstraumatic cervical nerve root avulsion-
post-operativepseudomeningocoele
-
intracranial neoplasms -
vascular abnormalitiesarteriovenous malformation (AVM)aneurysm-
fragile capillary regrowth after brain surgery2
-
cerebral amyloid angiopathy: seen in 60% of patients7 -
idiopathic: up to 46% of the time2
Overall Overall there is a male predilection (M:F 3:1) 2,5.
Clinical presentation
Symptoms can vary depending on the distribution of haemosiderin deposition. Common symptoms include 2-5:
-
sensorineural hearing loss
- most common, found in ~95% of patients
- bilateral and gradual
- cerebellar dysfunction (ataxia):
~88~90% - pyramidal signs:
~76~75% - other less common findings include
:- dementia
- bladder incontinence
- other cranial nerve dysfunction
- sensory deficits
It is important to realize that the degree of imaging abnormality does not always correlate with the degree of clinical impairment 4.
Pathology
Superficial siderosis is thought to result from recurrent occult subarachnoid bleeds although the source of bleeding is not usually identified in imaging 1. Although it is common to see a small amount of haemosiderin deposition at the margins of a previous haemorrhage or surgical resection margin, a single episode of subarachnoid haemorrhage is usually not sufficient to result in this condition 2.
Postulated etiologies include:
-
occult smallependymoma -
micro-arteriovenous malformation
Vestibulocochlear nerve (CN VIII) dysfuction,dysfunction resulting in sensorineural hearing loss is believed to be due to the combination of a long cisternal course (thus with ample exposure to the subarachnoid space) and the susceptibility of micorglialmicroglial cells (providing the myelin for the nerve) to damagebe damaged by iron compounds4.
Aetiology
A cause of recurrent subarachnoid haemorrhage is present in ~50% of cases 1-6,8:
-
spinal dural defects
- traumatic cervical nerve root avulsion
- post-operative pseudomeningocoele
-
intracranial neoplasms
- occult small ependymoma
- oligodendroglioma
- astrocytoma
-
vascular abnormalities
- arteriovenous malformation (AVM)
- aneurysm
- fragile capillary regrowth after brain surgery 2
- cerebral amyloid angiopathy: seen in 60% of patients7
- idiopathic: up to 46% of the time 2
Radiographic features
MRI
MRI is the modality of choice for assessment and diagnosis of superficial siderosis. The findings are characteristic, with all pial and ependymal surfaces (particularly of the brainstem and cerebellum: vermis and folia of the cerebellum are excellent locations to identify subtle deposits) coated with low signal haemosiderin. In long standing cases, cerebellar atrophy may also be present.
- T1: low signal
- T2: low signal
- GE (gradient echo): low signal with blooming
- SWI: low signal with blooming
As part of the work up for superficial siderosis, if no lesion is identified in the intracranial compartment, then imaging of the whole spinal canal should be performed (e.g. myxopapillary ependymoma) 5.
Angiography
Usually unrewarding and will not demonstrate a point of bleeding 1.
Treatment and prognosis
Unfortunately no proven direct treatment exist for established siderosis, and workup is focused on identifying the causative lesion, although often even this is not possible.
Iron Iron chelating agents have been tried with limited anecdotal success 6.
When no correctable cause is identified, signs and symptoms are slowly progressive.
-<p><strong>Superficial siderosis (SS)</strong> is a rare condition which results from deposition of haemosiderin along the leptomeninges, with eventual neurological dysfunction.</p><p>The literature is divided as to whether the term superficial siderosis should be confined to cases where there is no history of symptomatic subarachnoid haemorrhage, or whether it is a blanket term referring to the superficial deposition of haemosiderin, irrespective of cause. </p><p>For the purpose of this article, we take the later definition. </p><h4>Epidemiology</h4><p>As there are many causes of recurrent or extensive subarachnoid haemorrhage, the demographics are ill-defined and represent those of the underlying cause. Cases have been reported between 14 and 77 years of age <sup>5</sup>. Causes include <sup>1-6</sup>:</p><ul>- +<p><strong>Superficial siderosis (SS)</strong> is a rare condition which results from deposition of haemosiderin along the leptomeninges, with eventual neurological dysfunction.</p><p>The literature is divided as to whether the term superficial siderosis should be confined to cases where there is no history of symptomatic subarachnoid haemorrhage, or whether it is a blanket term referring to the superficial deposition of haemosiderin, irrespective of cause. </p><p>For the purpose of this article, we take the later definition. </p><h4>Epidemiology</h4><p>As there are many causes of recurrent or extensive subarachnoid haemorrhage, the demographics are ill-defined and represent those of the underlying cause. Cases have been reported between 14 and 77 years of age <sup>5</sup>. Overall there is a male predilection (M:F 3:1) <sup>2,5</sup>.</p><h4>Clinical presentation</h4><p>Symptoms can vary depending on the distribution of haemosiderin deposition. Common symptoms include <sup>2-5</sup>:</p><ul>
- +<li>
- +<a href="/articles/sensorineural-hearing-loss">sensorineural hearing loss</a><ul>
- +<li>most common, found in ~95% of patients</li>
- +<li>bilateral and gradual</li>
- +</ul>
- +</li>
- +<li>cerebellar dysfunction (ataxia): ~90%</li>
- +<li>pyramidal signs: ~75%</li>
- +<li>other less common findings include<ul>
- +<li><a href="/articles/dementia">dementia</a></li>
- +<li>bladder incontinence</li>
- +<li>other cranial nerve dysfunction</li>
- +<li>sensory deficits</li>
- +</ul>
- +</li>
- +</ul><p>It is important to realize that the degree of imaging abnormality does not always correlate with the degree of clinical impairment <sup>4</sup>. </p><h4>Pathology</h4><p>Superficial siderosis is thought to result from recurrent occult <a href="/articles/subarachnoid-haemorrhage">subarachnoid bleeds</a> although the source of bleeding is not usually identified in imaging <sup>1</sup>. Although it is common to see a small amount of haemosiderin deposition at the margins of a previous haemorrhage or surgical resection margin, a single episode of subarachnoid haemorrhage is usually not sufficient to result in this condition <sup>2</sup>. </p><p>Vestibulocochlear nerve (CN VIII) dysfunction resulting in sensorineural hearing loss is believed to be due to the combination of a long cisternal course (thus with ample exposure to the subarachnoid space) and the susceptibility of microglial cells (providing the myelin for the nerve) to be damaged by iron compounds <sup>4</sup>. </p><h5>Aetiology</h5><p>A cause of recurrent subarachnoid haemorrhage is present in ~50% of cases <sup>1-6,8</sup>:</p><ul>
-<li>post-operative <a href="/articles/pseudomeningocele">pseudomeningocoele</a>- +<li>post-operative <a href="/articles/pseudomeningocoele-1">pseudomeningocoele</a>
-<li><a href="/articles/ependymoma">ependymoma</a></li>- +<li>occult small <a href="/articles/ependymoma">ependymoma</a>
- +</li>
-<li><a href="/articles/cerebral-arteriovenous-malformation">arteriovenous malformation (AVM)</a></li>- +<li>
- +<a href="/articles/cerebral-arteriovenous-malformation">arteriovenous malformation (AVM)</a><ul><li>micro-<a href="/articles/cerebral-arteriovenous-malformation">arteriovenous malformation</a>
- +</li></ul>
- +</li>
-<li>fragile capillary regrowth after brain surgery <sup>2</sup>- +<li>fragile capillary regrowth after brain surgery <sup>2</sup>
-</ul><p>Overall there is a male predilection (M:F 3:1) <sup>2,5</sup>.</p><h4>Clinical presentation</h4><p>Symptoms can vary depending on the distribution of haemosiderin deposition. Common symptoms include <sup>2-5</sup>:</p><ul>-<li>sensorineural hearing loss<ul>-<li>most common, found in ~95% of patients</li>-<li>bilateral and gradual</li>-</ul>-</li>-<li>cerebellar dysfunction (ataxia): ~88%</li>-<li>pyramidal signs: ~76%</li>-<li>other less common findings include:<ul>-<li>dementia</li>-<li>bladder incontinence</li>-<li>other cranial nerve dysfunction</li>-<li>sensory deficits</li>-</ul>-</li>-</ul><p>It is important to realize that the degree of imaging abnormality does not always correlate with the degree of clinical impairment <sup>4</sup>. </p><h4>Pathology</h4><p>Superficial siderosis is thought to result from recurrent occult <a href="/articles/subarachnoid-haemorrhage">subarachnoid bleeds</a> although the source of bleeding is not usually identified in imaging <sup>1</sup>. Although it is common to see a small amount of haemosiderin deposition at the margins of a previous haemorrhage or surgical resection margin, a single episode of subarachnoid haemorrhage is usually not sufficient to result in this condition <sup>2</sup>. </p><p>Postulated etiologies include:</p><ul>-<li>occult small <a href="/articles/ependymoma">ependymoma</a>-</li>-<li>micro-<a href="/articles/cerebral-arteriovenous-malformation">arteriovenous malformation</a>-</li>-</ul><p>Vestibulocochlear nerve (CN VIII) dysfuction, resulting in sensorineural hearing loss is believed to be due to the combination of a long cisternal course (thus with ample exposure to the subarachnoid space) and the susceptibility of micorglial cells (providing the myelin for the nerve) to damage by iron compounds <sup>4</sup>. </p><h4>Radiographic features</h4><h5>MRI</h5><p>MRI is the modality of choice for assessment and diagnosis of superficial siderosis. The findings are characteristic, with all pial and ependymal surfaces (particularly of the brainstem and cerebellum: vermis and folia of the cerebellum are excellent locations to identify subtle deposits) coated with low signal haemosiderin. In long standing cases, <a href="/articles/cerebellar-atrophy">cerebellar atrophy</a> may also be present. </p><ul>- +</ul><h4>Radiographic features</h4><h5>MRI</h5><p>MRI is the modality of choice for assessment and diagnosis of superficial siderosis. The findings are characteristic, with all pial and ependymal surfaces (particularly of the brainstem and cerebellum: vermis and folia of the cerebellum are excellent locations to identify subtle deposits) coated with low signal haemosiderin. In long standing cases, <a href="/articles/cerebellar-atrophy">cerebellar atrophy</a> may also be present. </p><ul>
-</ul><p>As part of the work up for superficial siderosis, if no lesion is identified in the intracranial compartment, then imaging of the whole spinal canal should be performed (e.g. <a href="/articles/spinal-myxopapillary-ependymoma">myxopapillary ependymoma</a>) <sup>5</sup>. </p><h5>Angiography</h5><p>Usually unrewarding and will not demonstrate a point of bleeding <sup>1</sup>.</p><h4>Treatment and prognosis</h4><p>Unfortunately no proven direct treatment exist for established siderosis, and workup is focused on identifying the causative lesion, although often even this is not possible. </p><p>Iron chelating agents have been tried with limited anecdotal success <sup>6</sup>. </p><p>When no correctable cause is identified, signs and symptoms are slowly progressive. </p>- +</ul><p>As part of the work up for superficial siderosis, if no lesion is identified in the intracranial compartment, then imaging of the whole spinal canal should be performed (e.g. <a href="/articles/spinal-myxopapillary-ependymoma">myxopapillary ependymoma</a>) <sup>5</sup>. </p><h5>Angiography</h5><p>Usually unrewarding and will not demonstrate a point of bleeding <sup>1</sup>.</p><h4>Treatment and prognosis</h4><p>Unfortunately no proven direct treatment exist for established siderosis, and workup is focused on identifying the causative lesion, although often even this is not possible. Iron chelating agents have been tried with limited anecdotal success <sup>6</sup>. </p><p>When no correctable cause is identified, signs and symptoms are slowly progressive. </p>
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