Risks associated with oral deferiprone in the treatment of infratentorial superficial siderosis

Surgical closure of spinal cerebrospinal fluid leaks improves symptoms in patients with superficial siderosis

BACKGROUND AND PURPOSE

Spinal cerebrospinal fluid (CSF) leaks may cause a myriad of symptoms, most common being orthostatic headache. In addition, ventral spinal CSF leaks are a possible etiology of superficial siderosis (SS), a rare condition characterized by hemosiderin deposits in the central nervous system (CNS). The classical presentation of SS involves ataxia, bilateral hearing loss, and myelopathy. Unfortunately, treatment options are scarce. This study was undertaken to evaluate whether microsurgical closure of CSF leaks can prevent further clinical deterioration or improve symptoms of SS.

METHODS

This cohort study was conducted using data from a prospectively maintained database in two large spontaneous intracranial hypotension (SIH) referral centers in Germany and Switzerland of patients who meet the modified International Classification of Headache Disorders, 3rd edition criteria for SIH. Patients with spinal CSF leaks were screened for the presence of idiopathic infratentorial symmetric SS of the CNS.

RESULTS

Twelve patients were included. The median latency between the onset of orthostatic headaches and symptoms attributed to SS was 9.5 years. After surgical closure of the underlying spinal CSF leak, symptoms attributed to SS improved in seven patients and remained stable in three. Patients who presented within 1 year after the onset of SS symptoms improved, but those who presented in 8-12 years did not improve. We could show a significant association between patients with spinal longitudinal extrathecal collections and SS.

CONCLUSIONS

Long-standing untreated ventral spinal CSF leaks can lead to SS of the CNS, and microsurgical sealing of spinal CSF leaks might stop progression and improve symptoms in patients with SS in a time-dependent manner.

Infratentorial superficial siderosis: report of six cases and review of the literature

Objectives

To investigate the etiology, clinical manifestations, imaging features, and treatment of patients with infratentorial superficial siderosis (iSS), enhance clinicians' comprehension of this rare disease, and conduct oral deferiprone intervention and subsequent monitoring.

Methods

Six patients diagnosed with iSS based on magnetic resonance imaging (MRI) and susceptibility weighted imaging (SWI) were enrolled from 2021 to 2023 at the First Affiliated Hospital of Fujian Medical University. Their clinical datas were summarized, and the etiology and imaging characteristics were analyzed. Follow-up was conducted through telephone or outpatient visits.

Results

Among the 6 patients, there were 3 males and 3 females. The onset age ranged from 35 to 71 years, with an average onset age of 53 years. The clinical symptoms mainly included acoustic disturbances (6/6), gait imbalance (6/6), dysolfactory (6/6), cognitive impairment (2/6), epilepsy (2/6), and pyramidal tract sign (2/6). Evidence of superficial siderosis was observed on MRI across the cortex, brainstem, cerebellum, and spinal cord in all patients. T2-space sequence MRI revealed two instances of dural tear. During the follow-up period ranging from 1 month to 3 years, three patients who received oral deferiprone treatment showed improvement, whereas the remaining three patients who declined deferiprone treatment demonstrated progression.

Conclusion

The primary clinical manifestations of iSS include bilateral sensorineural hearing disturbances, progressive cerebellar ataxia, and spinal cord lesions. The key diagnostic criteria involve the presence of linear hypointensity on T2-WI in the surface region of the nervous system. Dural tear caused by various factors is considered to be the most common cause of iSS, and its treatment mainly involves surgical intervention for hemorrhagic primary diseases as well as pharmacotherapy with deferiprone.

Infratentorial Superficial Siderosis and Spontaneous Intracranial Hypotension

OBJECTIVE

Spontaneous spinal cerebrospinal fluid (CSF) leaks cause intracranial hypotension (SIH) and also may cause infratentorial superficial siderosis (iSS) but the rate of development among different CSF leak types and outcome of treatment are not known. We determined the time interval from SIH onset to iSS and the outcome of treatment.

METHODS

A total of 1,589 patients with SIH underwent neuroimaging and iSS was detected in 57 (23 men and 34 women, mean age = 41.3 years [3.6%]). We examined the type of underlying CSF leak by various imaging modalities. Percutaneous and surgical procedures were used to treat the CSF leaks.

RESULTS

The iSS was detected in 46 (10.3%) of 447 patients with ventral CSF leaks, in 2 (3.9%) of 51 patients with dural ectasia, in 5 (2.6%) of 194 patients with CSF-venous fistulas, in 4 (0.9%) of 457 patients with simple meningeal diverticula, and in none of the 101 patients with lateral CSF leaks or the 339 patients with leaks of indeterminate origin (p < 0.001). The estimated median latency period from SIH onset to iSS was 126 months. Ventral CSF leaks could not be eliminated with percutaneous procedures in any patient and surgical repair was associated with low risk (<5%) and resulted in resolution of the CSF leak in all patients in whom the exact site of the CSF leak could be determined. Other types of CSF leak were treated with percutaneous or surgical procedures.

INTERPRETATION

The iSS can develop in most types of spinal CSF leak, including CSF-venous fistulas, but mainly in chronic ventral CSF leaks, which require surgical repair. ANN NEUROL 2023;93:64-75.

Health-Related Quality of Life in Adults With Classical Infratentorial Superficial Siderosis: A Cross-sectional Study

BACKGROUND AND OBJECTIVES

Infratentorial superficial siderosis (iSS) is a rare but disabling neurologic condition characterized by progressive hearing loss and balance and mobility problems. The functional decline in these neurologic domains with iSS progression is likely to adversely affect health-related quality of life (HRQoL). We studied the HRQoL of adults with iSS using 2 common generic HRQoL measures (Health Utilities Index Mark III [HUI3] and EuroQoL EQ5D [5 Level]) to determine the most affected domains and evaluate the association between HRQoL scores and disease duration.

METHODS

This observational study was an anonymous online survey. Following institutional Research Ethics Committee approval, we contacted dedicated international organizations, charities, and patient groups identified through online searches, social media, and collaborative networks, to distribute the study information and study link, inviting their members diagnosed with iSS to participate. Participation required access to a digital device connected to the Internet, confirmation of eligibility (aged 18 years and older and previously diagnosed with iSS), and informed consent to participate in the survey, which included study-specific questions (demographics, iSS, and hearing) and HRQoL questionnaires. Survey responses were captured by the Research Electronic Data Capture survey software and analyzed using the SPSS statistical package. Linear regression analysis was performed to investigate the association between HRQoL scores and disease duration.

RESULTS

Of 50 participants, 60% were male; the median (interquartile range [IQR]) age was 60 (15) years. The median (IQR) multiattribute scores for HUI3 and EQ5D were 0.36 (0.53) and 0.64 (0.33), respectively. The most frequently affected domains (moderate or worse category) were hearing (64%) and pain (48%) for HUI3 and mobility (54%) and pain (50%) for EQ5D. There was a weak association between disease duration and multiattribute scores for HUI3 (R = 0.353; adjusted R2 = 0.096; b = -0.008; p = 0.047) but not EQ5D.

DISCUSSION

Our findings demonstrate low HRQoL scores that capture low functional status in several domains typically affected in iSS, suggesting that iSS has a major adverse effect on quality of life in multiple functional domains. Measures of HRQoL in iSS should be included in clinical and research settings, including treatment trials.

Olfactory dysfunction is common in classical infratentorial superficial siderosis of the central nervous system

Background

Established features of classical infratentorial superficial siderosis (iSS) include hearing loss, impaired balance, myelopathy and, less commonly, cognitive compromise. Olfactory function may be affected but dedicated studies are lacking. This study aimed to assess the prevalence of olfactory dysfunction in iSS and correlate it with auditory and cognitive functions.

Methods

Ten participants with iSS completed the University of Pennsylvania Smell Identification Test (UPSIT). The scores were compared with population norms; regression analysis was performed to evaluate associations between the scores and hearing thresholds (3-frequency average, 3FA) or the number of cognitive domains impaired. Imaging was reviewed for haemosiderin distribution and to exclude other causes of olfactory and hearing dysfunction.

Results

Eight of ten participants were male; the mean (standard deviation, SD) age was 52.5 (14.5) years. Olfactory hypofunction was identified in all participants and in six (60%) was moderate or completely absent. The mean UPSIT score of 25.5 (7.8) was significantly worse than population norms (difference in means − 10.0; 95% CI − 15.6 to − 4.4). Linear regression identified an association between UPSIT and hearing thresholds (R = 0.75; p = 0.013). The score decreases by 0.157 units (95% CI − 0.31 to − 0.002; p = 0.048) per unit increase in 3FA, after adjusting for hearing loss risk factors. There was no statistically significant association between UPSIT and cognitive function (R = 0.383; p = 0.397).

Conclusion

We report a high prevalence of olfactory dysfunction in iSS, the severity of which correlated with hearing loss. Olfaction appears to be a core feature of the iSS clinical syndrome that should be assessed routinely.

Classical infratentorial superficial siderosis of the central nervous system: pathophysiology, clinical features and management

The term superficial siderosis (SS) is derived from the Greek word 'sideros', meaning iron. It includes two subtypes, distinguished by their anatomical distribution, causes and clinical features: 'classical' infratentorial SS (iSS, which sometimes also affects supratentorial regions) and cortical SS (cSS, which affects only supratentorial regions). This paper considers iSS, a potentially disabling disorder usually associated with very slow persistent or intermittent subarachnoid bleeding from a dural defect, and characterised by progressive hearing and vestibular impairment, ataxia, myelopathy and cognitive dysfunction. The causal dural defect-most often spinal but sometimes in the posterior fossa-typically follows trauma or neurosurgery occurring decades before diagnosis. Increasing recognition of iSS with paramagnetic-sensitive MRI is leading to an unmet clinical need. Given the diagnostic challenges and complex neurological impairments in iSS, we have developed a multidisciplinary approach involving key teams. We discuss pathophysiology, diagnosis and management of iSS, including a proposed clinical care pathway.

Superficial Siderosis: A Clinical Review

Superficial siderosis of the central nervous system results from subpial hemosiderin deposition due to chronic low-grade bleeding into the subarachnoid space. The confluent and marginal subpial hemosiderin is best appreciated on iron-sensitive magnetic resonance imaging sequences. With widespread use of magnetic resonance imaging, the disorder is increasingly being recognized, including in asymptomatic individuals. Gait ataxia, often with hearing impairment is a common clinical presentation. A clinical history of subarachnoid hemorrhage is generally not present. A macrovascular pathology is generally not causative. The most common etiology is dural disease, often dural tears. Prior or less commonly ongoing symptoms of craniospinal hypovolemia may be present. Common etiologies for dural tears include disc disease and trauma, including surgical trauma. Patients with dural tears due to herniated and calcified discs often have a ventral intraspinal fluid collection due to cerebrospinal fluid leak. A precise identification of the dural tear relies on multimodality imaging. It has been speculated that chronic bleeding from fragile blood vessels around the dural tear may be the likely underlying mechanism. Surgical correction of the bleeding source is a logical therapeutic strategy. Clinical outcomes are variable, although neuroimaging evidence of successful dural tear repair is noted. The currently available data regarding use of deferiprone in patients with superficial siderosis is insufficient to recommend its routine use in patients. ANN NEUROL 2021;89:1068-1079.

Case Report: Auditory Neuropathy and Central Auditory Processing Deficits in a Neuro-Otological Case-Study of Infratentorial Superficial Siderosis

Hearing and balance impairment are the most frequently reported features of infratentorial (classical) superficial siderosis (iSS). There are few comprehensive descriptions of audiovestibular function in iSS and therefore limited understanding of the affected segment(s) of the audiovestibular pathway. In addition, monitoring disease progression and response to treatment is challenging and currently mainly guided by subjective patient reports and magnetic resonance imaging. To the best of our knowledge, there have been no previous reports assessing central auditory function in iSS. We describe such findings in a patient with iSS in an attempt to precisely localize the site of the audiovestibular dysfunction, determine its severity and functional impact. We confirm the presence of (asymmetrical) auditory neuropathy and identify central auditory processing deficits, suggesting involvement of the central auditory pathway beyond the brainstem. We correlate the audiological and vestibular findings with self-report measures and the siderosis appearances on brain magnetic resonance images.

Treatment Response of Deferiprone in Infratentorial Superficial Siderosis: a Systematic Review

Superficial siderosis describes haemosiderin deposition on the surface of the brain. When present on infratentorial structures, it can cause ataxia, sensorineural hearing loss and pyramidal signs. There is no proven treatment and patients experience slow progression of symptoms. Iron-chelating agents have been suggested as a therapeutic option and deferiprone is suited as it crosses the blood-brain barrier. However, deferiprone is reported to have a 1–2% risk of agranulocytosis. We performed a systematic review on treatment of infratentorial superficial siderosis with deferiprone based on PRISMA guidelines. Studies were included if in English or an English language translation was available, were about human subjects and referred to patients with ataxia. Studies were excluded if they did not possess an English translation, included animal studies or did not have ataxia. Studies were excluded if they discussed cerebral amyloid angiopathy or siderosis of other regions. Eleven papers were included. We identified 69 patients. Seventeen patients (25%) discontinued the drug. The most encountered adverse effect was anaemia (21.7%). Neutropaenia was observed in 8.7% and agranulocytosis in 5.8% of patients. Clinically, response varied, and stability or improvement was seen across neurological domains in 6 studies while 5 showed a mixed response. On imaging, 13 (28.9%) patients improved, 24 (53.3%) stabilised and 8 (17.8%) deteriorated. A prospective international centralised register of patients should be developed to inform the design and conduct of a multicentre, placebo-controlled, randomised clinical trial to evaluate the efficacy of deferiprone. The evidence from this systematic review is that deferiprone is a promising intervention.

Neurological update: neuroimaging in dementia

Neuroimaging for dementia has made remarkable progress in recent years, shedding light on diagnostic subtypes of dementia, predicting prognosis and monitoring pathology. This review covers some updates in the understanding of dementia using structural imaging, positron emission tomography (PET), structural and functional connectivity, and using big data and artificial intelligence. Progress with neuroimaging methods allows neuropathology to be examined in vivo, providing a suite of biomarkers for understanding neurodegeneration and for application in clinical trials. In addition, we highlight quantitative susceptibility imaging as an exciting new technique that may prove to be a sensitive biomarker for a range of neurodegenerative diseases. There are challenges in translating novel imaging techniques to clinical practice, particularly in developing standard methodologies and overcoming regulatory issues. It is likely that clinicians will need to lead the way if these obstacles are to be overcome. Continued efforts applying neuroimaging to understand mechanisms of neurodegeneration and translating them to clinical practice will complete a revolution in neuroimaging.

A Novel Star Like Eight-Arm Polyethylene Glycol-Deferoxamine Conjugate for Iron Overload Therapy

The traditional iron chelator deferoxamine (DFO) has been widely used in the treatment of iron overload disease. However, DFO has congenital disadvantages, including a very short circular time and non-negligible toxicity. Herein, we designed a novel multi-arm conjugate for prolonging DFO duration in vivo and reducing cytotoxicity. The star-like 8-arm-polyethylene glycol (8-arm-PEG) was used as the macromolecular scaffold, and DFO molecules were bound to the terminals of the PEG branches via amide bonds. The conjugates displayed comparable iron binding ability to the free DFO. Furthermore, these macromolecule conjugates could significantly reduce the cytotoxicity of the free DFO, and showed satisfactory iron clearance capability in the iron overloaded macrophage RAW 246.7. The plasma half-life of the 8-arm-PEG-DFO conjugate was about 190 times than that of DFO when applied to an intravenously administered rat model. In conclusion, research indicated that these star-like PEG-based conjugates could be promising candidates as long circulating, less toxic iron chelators.