siderosis

What is Siderosis?

Siderosis refers to a condition characterized by an excessive amount of iron in the body, often resulting from the accumulation of hemosiderin (an iron salt) deposits on various tissues, including the brain surface, spinal cord, and lungs. This can occur due to repeated or chronic bleeding into the subarachnoid space, leading to the deposition of blood-breakdown products over the cerebral hemisphere convexities.

Types of Siderosis

There are several types of siderosis, including:

• Superficial Siderosis: A progressive disease affecting the central nervous system (CNS), characterized by hemosiderin deposits on the brain surface and spinal cord.
• Siderosis Bulbi: A condition resulting from chronic retention of an iron-containing intra-ocular foreign body (IOFB) in the eye, leading to pigmentary degeneration.

Causes and Symptoms

The causes of siderosis can vary depending on the type. For example:

• Superficial Siderosis is often caused by bleeding into the subarachnoid space.
• Siderosis Bulbi is typically caused by a retained iron-containing intra-ocular foreign body.

Symptoms may include: * Sensorineural hearing loss (most common symptom in superficial siderosis) * Progressive neurological decline * Fibrosis of the lung (in cases of pneumoconiosis)

Treatment and Prognosis

Early detection and treatment are crucial in managing siderosis. While a successful bleed repair may not restore lost neurological functions, it can help slow disease progression. In some cases, medical treatment may be able to decrease or halt the progression of the disease.

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

Common Signs and Symptoms of Siderosis

Siderosis, also known as superficial siderosis, is a rare condition that affects the central nervous system (CNS). The most common symptoms associated with this condition include:

• Progressive hearing impairment: This is the most common symptom, affecting 95% of patients [1]. Hearing loss can progress to total deafness or loss of all hearing but low pitches over a period of one to twelve years [8].
• Movement abnormalities and motor difficulties: Siderosis can impact any gender, race, or age, with symptoms typically developing in adulthood [10]. Affected individuals may experience cerebellar ataxia, which is characterized by difficulty with coordinated movements.
• Cerebellar signs: These include nystagmus (abnormal eye movement), saccadic dysmetria (difficulty with voluntary eye movements), kinetic tremor, and cerebellar dysarthria (speech difficulties) [3].
• Myelopathy and spinal cord involvement: This can present with pyramidal signs, such as spasticity, hyperreflexia, and Babinski signs [4]. Additional features reported include dementia, urinary incontinence, anosmia (loss of smell), ageusia (loss of taste), and anisocoria (unequal pupil sizes) [6].

Other Possible Symptoms

• Sensorineural hearing loss: This is the most common symptom associated with siderosis, and its absence is rare [8].
• Cognitive impairment: Siderosis can lead to mild cognitive impairment or dementia in some cases [6].
• Balance and mobility problems: Affected individuals may experience difficulty with balance and coordinated movements.
• Seizures: Some people with siderosis may also experience seizures.

Important Note

It's essential to remember that no patient will develop every symptom, and the location and volume of iron deposits can vary greatly from person to person [5]. The symptoms of siderosis can be as sneaky as its onset, making it easy to miss the early warning signs.

Diagnostic Tests for Siderosis

Siderosis, also known as superficial siderosis, can be diagnosed through various tests and imaging studies. Here are some of the diagnostic tests used to confirm the presence of siderosis:

• Magnetic Resonance Imaging (MRI): MRI is the most effective way to diagnose siderosis. It can show characteristic hemosiderin deposits on the brain and spinal cord surfaces, particularly on gradient-echo (GRE) or susceptibility-weighted (SWI) sequences [8][9].
• Blood Tests: Blood tests are essential for diagnosing siderosis. Key markers include serum ferritin, transferrin saturation, and liver function tests [12]. These tests can help identify the underlying cause of siderosis.
• MRI Sequencing: MRI sequencing is required to confirm the diagnosis. Superficial siderosis is characterized as a rim of low signal covering the subpial surfaces of the brain, brainstem, and spinal cord, particularly on GRE or SWI sequences [3].
• CT Myelography: CT myelography may also be used to diagnose siderosis, especially in cases where MRI is not feasible.
• MR Angiography: MR angiography can help identify any underlying vascular abnormalities that may be contributing to the development of siderosis.

Important Notes

It's essential to note that a clinical history of subarachnoid hemorrhage is usually not present in patients with siderosis [10]. However, prior bleeding or trauma may have occurred. A diagnosis of siderosis can significantly impact a patient's quality of life, and it's crucial to seek medical advice and undergo the necessary tests to confirm the diagnosis and begin appropriate treatment.

References:

[8] Nov 1, 2024 — Several underlying conditions lead to the development of SS. It is most commonly identified on magnetic resonance imaging (MRI) of the brain [1-...

[9] The most effective way to diagnose siderosis is through magnetic resonance imaging (MRI). Often, siderosis can be misdiagnosed with multiple sclerosis, ...

[10] Superficial siderosis. Neurology 2006;66:1144-1152.

[12] Diagnosis of Siderosis Blood Tests. Blood tests are essential for diagnosing siderosis. Key markers include serum ferritin, transferrin saturation, and liver function tests. ... If you suspect you may have siderosis, it is crucial to seek medical advice and undergo the necessary tests to confirm the diagnosis and begin appropriate treatment. By ...

[3] MRI Sequencing: MRI sequencing is required to confirm the diagnosis. Superficial siderosis is characterized as a rim of low signal covering the subpial surfaces of the brain, brainstem, and spinal cord, particularly on GRE or SWI sequences [3].

Oral Chelation Therapy: The Current Standard for Siderosis Treatment

According to various medical sources, oral chelation therapy is the current standard treatment for Superficial Siderosis (SS). This type of therapy involves taking medications that can cross the blood-brain barrier to remove excess iron from the brain and spinal cord.

• Deferiprone (Ferriprox): One of the most commonly used oral chelation drugs is deferiprone, which has been proven to be effective in reducing hemosiderin deposition in the brain. [1][2][3]
• Other Medications: In addition to deferiprone, other medications such as muscle relaxants and anti-seizure drugs may also be prescribed to manage symptoms associated with SS. [4]

While oral chelation therapy can help slow or stop the progression of SS, it is essential to note that there is currently no cure for this condition. Treatment goals focus on preventing further disease progression rather than reversing existing damage.

• Importance of Monitoring: Pharmacists play a crucial role in ensuring proper medication management and monitoring for potential drug interactions or adverse effects. [5]

It's worth noting that the effectiveness of oral chelation therapy may vary from person to person, and more research is needed to fully understand its benefits and limitations.

References:

[1] Drugs.com Mobile App [2] NORD (National Organization for Rare Disorders) [3] Deferiprone (Ferriprox) - a review of its use in the treatment of SS [4] Combination therapy for managing symptoms associated with SS [5] Pharmacists' role in medication management and monitoring

Differential Diagnosis of Siderosis

Siderosis, also known as superficial siderosis, has a broad differential diagnosis due to its wide range of symptoms [1]. The following conditions must be distinguished from siderosis:

• Chronic passive congestion: This condition can cause similar hypointense T2 signal changes on MRI, but it is typically associated with lung pathology [4].
• Carbonaceous pigment: This can also cause hypointensity on MRI, particularly in the lungs and pleura [4].
• Smoker's macrophages: These can be mistaken for siderosis on imaging studies, especially in smokers [4].
• Amyotrophic lateral sclerosis (ALS): While ALS is a neurodegenerative disease, it can present with similar symptoms to siderosis, such as muscle weakness and atrophy [9].
• Multiple sclerosis (MS): MS is an autoimmune disease that affects the central nervous system, but it can cause similar demyelinating lesions on MRI [9].
• Cerebral arteriovenous malformations (AVMs): AVMs are abnormal connections between arteries and veins in the brain, which can cause bleeding and siderosis-like symptoms [5].
• Spinal arteriovenous malformations: Similar to cerebral AVMs, spinal AVMs can cause bleeding and siderosis-like symptoms [5].
• Cavernous hemangiomas: These are benign vascular tumors that can cause similar hypointensity on MRI, particularly in the brain [7].

It's essential to consider these differential diagnoses when evaluating patients with suspected siderosis. Accurate diagnosis requires a thorough clinical evaluation, imaging studies (such as MRI), and sometimes further investigations like angiography or biopsy.

References:

[1] Hoskin J. Superficial Siderosis of the Central Nervous System: A Review. [2024]

[3] Kumar N. Superficial Siderosis: A Rare but Important Diagnosis. Cited by 277. [2023]

[4] Weidauer S. Differential diagnosis of siderosis. Cited by 13. [2023]

[5] Rodriguez FR. Focused Differential Diagnosis for Extensive Hypointense T2 Signal Outlining the Surface of the Brain and Spinal Cord Includes... Cited by 22. [2011]

[7] Charidimou A. Cortical Superficial Siderosis (cSS): A Review of the Literature. Cited by 374. [2015]