Otology & Neurotology
24:90–95 © 2003, Otology & Neurotology, Inc.

Superficial Siderosis of the Meninges and Its
Otolaryngologic Connection: A Series of
Five Patients
*S. U. Kale, *I. Donaldson, †R. J. West, and ‡A. Shehu
*Departments of Ear, Nose, and Throat and †Radiology, University Hospital, Birmingham, and
‡Department of General Medicine, Walsgrave Hospital, Coventry, UK

Objective: To study the otolaryngologic disorders in patients
with superficial siderosis of the meninges.
Background: Superficial siderosis of the central nervous system is a rare disorder characterized by progressive bilateral
hearing loss and ataxia caused by recurrent bleeding into the
subarachnoid space. The cerebellum, eighth cranial nerve, and
olfactory nerve are particularly susceptible to the deposition of
hemosiderin, which is responsible for the symptoms. The diagnosis is confirmed by magnetic resonance imaging.
Methods: The clinical notes of five patients with superficial
siderosis of the meninges were reviewed with the intent of

reporting the otolaryngologic symptoms and signs, the clinical
investigations, and treatments.
Results: Four of the five patients had sensorineural deafness,
two had smell disturbances, and three had gait abnormalities.
Magnetic resonance imaging was the most important investigation used to identify the condition.
Conclusions: Superficial siderosis of the meninges is an important differential diagnosis in patients with progressive sensorineural deafness. Key Words: Superficial siderosis—
Sensorineural deafness—Ataxia.
Otol Neurotol 24:90–95, 2003.

Progressive sensorineural deafness has various causes,
which include presbyacusis, multiple sclerosis, neurosyphilis, and autoimmune disorders. Superficial siderosis
of the central nervous system as a cause of sensorineural
deafness is a known but rare condition. The cardinal
symptoms are progressive sensorineural deafness and
ataxia. The condition commonly presents with progressive bilateral hearing loss, but initially there may be a
unilateral presentation. Magnetic resonance imaging
(MRI) is valuable in diagnosing the condition, which
results from recurrent subarachnoid bleeding. The site of
the bleeding is not always identified despite full angiographic investigation.

neurologic symptoms. Her medical history revealed hypertension, which was well controlled with Enalapril.
Examination of her ears, nose, and throat did not show
any abnormality. Examination of olfaction using the University of Pennsylvania smell identification test revealed
hyposmia. The other cranial nerves were normal. There
were no positive cerebellar signs, the results of Romberg’s test and tandem gait testing were normal, and
there was no nystagmus. Pure tone audiometry revealed
a unilateral sensorineural deafness on the right with
thresholds at 65 dB at the higher frequencies and 45
dB at 1,000 Hz. The left side revealed thresholds of 25
and 40 dB at 4,000 and 8,000 Hz, respectively (Figs. 1
and 2). MRI was performed in a search for an explanation of the unilateral deafness, and revealed siderosis of
the meninges (Fig. 3), confined to the cerebellar hemispheres and the superior vermis. These structures were
coated in iron. There was some cerebellar atrophy. There
was no visible cause of persistent bleeding. The condition was explained to the patient, and she was offered a
hearing aid but declined further investigations into the
cause of the condition because she did not perceive her
symptoms as being severe. She now attends her yearly
follow-up appointments.
Case 2
A 39-year-old man with profound bilateral sensorineural deafness was referred for assessment for cochlear

CASE REPORTS
The clinical features of the five patients are given in
Tables 1, 2, and 3.
Case 1
A 70-year-old woman with hypertension had experienced progressive right-sided hearing loss for 6 years.
On inquiry, she further described having hyposmia over
the same period. There was no history of imbalance or
Address correspondence and reprint requests to Savita U. Kale, 77
Christchurch Close, Edgbaston, Birmingham, UK; e-mail:
asu.kale@ukgateway.net

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SUPERFICIAL SIDEROSIS AND DEAFNESS
TABLE 1. Clinical examination
Patient

Age/Sex

Symptoms and signs

1

70/F

2

39/M

3

35/M

4

18/M

5

33/M

Unilateral sensorineural deafness, hyposmia, no
cerebellar signs
Bilateral sensorineural deafness, anosmia,
cerebellar ataxia, dysarthria, nystagmus
Bilateral sensorineural deafness, progressive gait
difficulty, dysarthria
Headache, nausea, vomiting, history of excision
of a posterior fossa astrocytoma; no cerebellar
signs, no cranial nerve palsy, no hearing loss
Bilateral sensorineural deafness decreased visual
acuity, dysarthria, progressive deterioration of
gait, ataxia, incoordination, history of excision
of posterior fossa astrocytoma

implant insertion. He had initially sought treatment at the
age of 35 for bilateral hearing loss and was supplied with
a hearing aid. His hearing had started deteriorating at the
age of 21 years, when he experienced right-sided sensorineural deafness, followed 4 years later by deterioration
on the left. His history revealed surgical excision of a
cerebellar astrocytoma at the age of 5 years, with no
history of radiotherapy. His hearing loss progressed; he
had progressive ataxia, deterioration of his short-term
memory, and anosmia; and he was therefore referred to a
neurologist. Neurologic examination revealed dysarthria,
nystagmus on lateral and upward gaze in both eyes in the
direction of gaze, cerebellar ataxia of the limbs, inability
to walk heel to toe, and a negative Romberg’s test result.
There was no ophthalmoplegia. Pure tone audiometry
(Figs. 4 and 5) revealed profound sensorineural loss at all
frequencies in both ears except for an island of hearing at
the lower frequencies in the left ear. Magnetic resonance
imaging revealed a discrete cystic structure 2 cm in diameter in the right cerebellar hemisphere with some dilatation of the fourth ventricle. A second MRI scan performed 3 months later using Fluid Attenuation Inversion
Recovery and gradient-echo T2-weighted signals
showed prominent penciling in of the meninges about the
brain (Fig. 6), involving the posterior fossa contents, the
basal cistern, and over the convexities with cerebellar
atrophy. MRI of the spine did not reveal any arteriove-

91

nous malformations. Examination of the cerebrospinal
fluid (CSF) showed a protein level of 3,440 mg/L and a
normal glucose level. The patient has had regular followup care and help with his disabilities, but because of the
progressive nature of the illness he has not received a
cochlear implant.
Case 3
A 35-year-old man had sought treatment at the age of
32 with a history of progressive difficulty in walking
since 2 years of age, bilateral progressive hearing loss,
and dysarthria over 1 year. His history revealed a skull
fracture at the age of 30 months. Neurologic examination
revealed spastic paraparesis with brisk reflexes and upgoing plantar reflexes with a wide-based gait and inability to walk heel to toe, dysarthria, and bilateral sensorineural deafness on tuning fork tests, but no abnormality
of other cranial nerves or any other cerebellar signs. Examination of the CSF showed a protein level of 1.49 g/L,
a normal glucose level, xanthochromia, and a markedly
raised ferritin level of 99 ␮g/L. MRI showed hemosiderin staining of the surface of an atrophic cerebellum and
atrophy of the spinal cord throughout its extent. A cerebral angiogram did not reveal any abnormality. Evoked
response audiometry showed an abnormal waveform on
the left with increased wave I–V latency of 4.82 milliseconds, compared with 4.0 milliseconds on the right. He
was prescribed trientine hydrochloride, 600 milligrams
twice a day, to reduce the iron deposition and to prevent
the progression of his symptoms. He was being followed
up with repeated lumbar punctures to check CSF ferritin
levels but then refused any further CSF examinations.
His neurologic status has been stable over the follow-up
period of 3 years.
Case 4
An 18-year-old man was initially brought for treatment at the age of 10 with headache, vomiting, and diplopia. Computed tomography showed a posterior fossa
tumor, which was confirmed on craniotomy to be a cystic
astrocytoma. He underwent complete surgical excision
of this midline cerebellar astrocytoma. Eight years after
the surgical treatment, he experienced headache, vomit-

TABLE 2. Investigations
Patient

Audiometry

1

Right sensorineural deafness

2

Bilateral profound sensorineural deafness

3

Increased wave 1–5 latency on left on
evoked response audiometry

4

None

5

None

Magnetic resonance imaging
Siderosis of meninges of cerebellar
hemispheres
Siderosis of meninges of posterior fossa
contents
Siderosis of cerebellar surface; brainstem
and spinal cord atrophy
Siderosis of meninges on superior
cerebellar surface and floccular nodular
lobes
Siderosis of arachnoid of posterior fossa,
spinal cord temporal lobes; spinal cord
atrophy

Other
Smell test: hyposmia
CSF examination revealed raised proteins
CSF examination revealed xanthochromia,
raised proteins, and ferritin levels;
cerebral angiogram
None

None

CSF, cerebrospinal fluid.
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S. U. KALE ET AL.
TABLE 3. Likely causes

Patient

Likely lesion responsible

1
2

Nil
Bleeding at previous operation
site
Previous head injury
Bleeding at previous operation
site
Bleeding at previous operation
site

3
4
5

Treatment
Yearly follow-up
Regular follow-up
Trientine
Neurosurgical follow-up
Regular follow-up

ing, and generalized fatigue. Clinical examination revealed normal gait, no cranial nerve palsy and no cerebellar signs. He did not describe any hearing
impairment. MRI revealed a recurrence of the astrocytoma with an associated large cyst, which subsequently
required reoperation. Postoperatively, a CSF leak from
the wound was detected and required insertion of a lumbar drain for 5 days. Follow-up MRI 8 months later
revealed siderosis of the meninges and superior cerebellum, and floccular nodular lobes. He is being regularly
followed up by the neurosurgeons with plans for further
imaging.
Case 5
A 33-year-old man had received a diagnosis of cerebellar astrocytoma at the age of 8 years and had undergone surgery for it. The astrocytoma recurred, and he
underwent repeat surgery 10 years later with the insertion of a shunt. His clinical symptoms included progressive severe bilateral deafness, which was noticed 10
years after the first operation, and restricted vision bilaterally. Twelve years after his second operation he sought
treatment for slurred speech and imbalance and was seen
to have positive cerebellar signs, which had not been
present previously. Clinical examination revealed lower
limb ataxia, incoordination, increased tone in the lower
limbs, dysarthria, and horizontal nystagmus on lateral

FIG. 1. Pure tone audiogram of right ear, Case 1.
Otology & Neurotology, Vol. 24, No. 1, 2003

FIG. 2. Pure tone audiogram of left ear, Case 1.

gaze. Computed tomography performed at this presentation revealed a cyst in the posterior fossa, with cerebellar
atrophy, collapsed ventricles, and a ventricular catheter.
Neurologic follow-up studies revealed progressive deterioration of gait. Repeat MRI performed at age 33 revealed superficial siderosis of the arachnoid of the posterior fossa, parts of the temporal lobe, and the spinal
cord, which explained the progression of his neurologic
symptoms. No specific treatment was given, and he is
receiving regular follow-up monitoring. Radiotherapy
was not used in the treatment at any stage.
DISCUSSION
Superficial siderosis of the central nervous system is a
condition characterized by intracellular and extracellular
deposition of hemosiderin in the leptomeninges, subpial
tissue, spinal cord, and cranial nerves. Deposition of hemosiderin is associated with gliosis, neuronal loss, and
demyelination. Clinically, the condition has been characterized by a combination of sensorineural deafness,
cerebellar ataxia, dementia, anosmia, myelopathy, and
chronic subarachnoid hemorrhage. The male:female ratio
is 3:1, and our series also had more men. The disorder is
not restricted to any age group, and some degree of siderosis can be seen in neonates who survive hemorrhagic
lesions. Our patients ranged from 18 to 70 years of age at
diagnosis. In another series of 8 patients from one center,
the range was 25 to 77 years (1).
Hearing impairment is an important feature, and its
absence is exceptional. Of 63 cases reported in the world
literature to 1995, hearing loss was present in 53 patients
of the 56 in whom this presenting symptom was documented (2). The hearing loss can be asymmetric initially,
as in our first two patients and in the case reported by
Fearnley et al. (2). The hearing loss is retrocochlear, as

SUPERFICIAL SIDEROSIS AND DEAFNESS

FIG. 3. Magnetic resonance imaging scan of patient in Case 1.
Arrow indicates siderosis over the cerebellar hemispheres.

93

FIG. 5. Pure tone audiogram of left ear, Case 2.

explained by the pathologic changes, and this is illustrated by the increased wave 1 to 5 latency on evoked
response audiometry in our third case.
The duration of disease, from the onset of the first
symptom to the time of death, can be very long, and
cerebellar deficits are almost as common as the hearing
loss but take longer to develop. Three patients from our
series had cerebellar ataxia; however, the other two are
free of cerebellar dysfunction at this writing. In the review of cases reported by Fearnley et al. (2), 50 of 57
patients had cerebellar ataxia, of whom 17 had gait ataxia

without affection of the limbs. Three of our patients had
gait ataxia.
Anosmia is a symptom that is not frequently looked
for, and two of our patients did have disturbances of
smell. Dementia is less common than the other main
components of siderosis and was seen in two of our
cases. Fearnley et al. (2) reported dementia in 24% and
anosmia in 17% of patients in their review of reported
cases. There seemed to be no correlation between the
duration of the disease and the severity of the lesion.
The eighth cranial nerve is often the first to be affected, and the olfactory bulb is the next most commonly

FIG. 4. Pure tone audiogram of right ear, Case 2.

FIG. 6. Magnetic resonance imaging scan of patient in Case 2.
Arrow indicates siderosis.
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S. U. KALE ET AL.

affected cranial nerve. Three of our patients presented
with affection of the eighth cranial nerve, and two of our
patients also had affection of the olfactory nerve. The
fourth patient does not have any hearing loss at this
writing. The optic nerve may be affected, and one of our
patients has decreased visual acuity whose cause is uncertain. Extraocular nerve paresis and facial nerve paresis have been reported (2).
The greater susceptibility of the cerebellar cortex and
the eighth cranial nerve is due to the accelerated biosynthesis of ferritin in microglia in these areas, as explained
by Koeppen and Dentinger (3). They raised the possibility that ferritin synthesis was neuroprotective by binding
iron released from red cells in the CSF, and tissue damage occurred once this reserve was exhausted. Persistent
hemorrhagic CSF stimulates microglia cells in the subpial parenchyma, inducing an accelerated ferritin biosynthesis. Iron-containing heme pigments and free iron molecules are taken up from the CSF by Bergmann glia and
are stored in macrophages and glial cells. The first iron
storage takes place in the form of iron ferritin, and this is
later transformed to hemosiderin, which causes the rustybrown staining of the brain surface. When the ironbinding capacity is exceeded, free ionic iron induces
lipid peroxidation, leading to parenchymal damage and
neuronal cell death with secondary gliosis (4).
The eighth cranial nerve has a long glial segment, and
because it retains its glial sheath up to the internal auditory canal, it is particularly vulnerable to heavy impregnation with hemosiderin. In addition, the vestibulocochlear nerve runs through the pontine cistern and is
exposed to a large pool and a greater flow of CSF. This
potentially delivers a large amount of iron and heme,
causing a greater degree of neuronal damage. The olfactory tract and bulb are similarly affected because of the
presence of a glial sheath.
Necrosis of the cortex secondary to hemosiderin deposition can result in dementia (5), which was one of
the presenting symptoms in our second patient. Involvement of the brainstem is very common in superficial
siderosis, and the central nervous system parenchyma
can be involved for a depth of up to 3 mm. This could
result in damage to the cochlear nuclei in the floor of the
fourth ventricle. In addition, widespread cerebral involvement, including destruction of the auditory cortex,
has been described.
This condition can theoretically involve the auditory
pathway at multiple sites (6). Castelli et al. (7) reported
a case of siderosis with a cerebellopontine angle ependymoma, in which delayed central conduction time on
brainstem-evoked responses occurred. Our third patients
also had increased wave I to V latency on the left on
evoked response audiometry.
The majority of reported cases of superficial siderosis
involve episodes of recurrent bleeding into the CSF from
various causes such as tumors, aneurysms, arteriovenous
malformations, previous operations such as hemispherectomy, or neonatal intraventricular hemorrhage
(2). Alteration of the normal anatomy by surgery or raOtology & Neurotology, Vol. 24, No. 1, 2003

diotherapy can produce a source of hemorrhage and result in the condition. This sequence of events was reported by River et al. in a patient with a cerebellar
astroblastoma who had surgical excision followed by radiotherapy; this caused telangiectasia within the cavity
wall, which was a source of hemorrhage (8). Our second
patient had undergone a neurosurgical procedure at the
age of 5 years for the removal of a cerebellar astrocytoma
but no radiotherapy. Our fourth patient had undergone
excision of an astrocytoma at the age of 11 years, and our
fifth patient had undergone excision of an astrocytoma at
the age of 8 years. It can be speculated that there may
have been a source of bleeding at the site of previous
surgery, which resulted in siderosis of the meninges. Kumar et al. (9) proposed in 1993 that surgery might inadvertently provide access to the CSF for a bleeding source
within the brain, resulting in superficial siderosis. This
may also explain the lesion in three of our patients who
had undergone previous surgery. In some cases there is
no detectable cause, as seen in our third patient, whose
angiogram did not reveal any malformation that could
have been responsible for recurrent bleeding.
In the past, the diagnosis of superficial siderosis was
made on autopsy but since the introduction of MRI, it is
now being recognized in the presymptomatic condition.
MRI can easily demonstrate even small deposits of ironcontaining pigments because of their marked paramagnetic effect. T2-weighted images reveal a marginal hypointensity resulting from the presence of ferric ions.
This surrounds the midbrain, pons, medulla oblongata,
and spinal cord in the majority of the cases (2). The
erratic clumpy distribution of paramagnetic hemosiderin
causes local heterogeneous magnetic field gradients with
shortened relaxation times and, therefore, hypointense
images on T2-weighted MRI (5). All the patients received MRI scans, which revealed the characteristic marginal hypointensity caused by the hemosiderin. However, in our fourth patient the condition was most likely
in the presymptomatic stage.
The main CSF findings in superficial siderosis are
hemorrhage and xanthochromia. Other features include
raised protein, iron, and ferritin levels (1). CSF protein
levels were raised in both our patients in whom CSF
examination was done, and the third patient also had
raised ferritin levels.
Treatment of this condition is mainly limited to identification of the bleeding site and its surgical ablation.
One of our patients did have an angiogram to detect a
source of bleeding, which was inconclusive; however,
patients 1 and 2 declined further investigations. The
cause of bleeding is often not apparent, and in the series
reported by Fearnley et al., the bleeding point was identified in only 54% of the patients (2).
Trientine has been used to reduce the iron in the CSF.
It was first used in Wilson’s disease to reduce serum
copper levels, where it was noticed to have reduced the
serum iron in addition (10), and because it crosses the
blood-brain barrier it was applied in the treatment of
siderosis. River et al. (8) reported its positive effect in

SUPERFICIAL SIDEROSIS AND DEAFNESS
slowing the progression of the disease in one patient over
a 2-year follow-up period. The dose used was 2 g per
day. Our third patient is receiving trientine, and there has
been no deterioration of his neurologic status over a
3-year follow-up.
The hearing loss is managed by amplification with
hearing aids and serial audiometry, because we know it is
a progressive disease. Cochlear implantation has been
performed in one reported patient with bilateral profound
hearing loss due to superficial siderosis and found to be
effective in raising the auditory thresholds. However, the
authors themselves explain that superficial siderosis is a
progressive condition, and the benefits of cochlear implantation may be only temporary (6).

CONCLUSION
Superficial siderosis of the central nervous system
should be considered in the differential diagnosis of a
unilateral and even bilateral sensorineural deafness especially if the deafness is progressive with or without
ataxia or alteration of sense of smell. MRI is helpful in
early diagnosis of superficial siderosis. Surgical treatment of the bleeding source is the mainstay of treatment.

95

REFERENCES
1. Parnes SM, Weaver SA. Superficial siderosis of the central nervous system: a neglected cause of sensorineural hearing loss. Otolaryngol Head Neck Surg 1992;107:69–77.
2. Fearnley JM, Stevens JM, Rudge P. Superficial siderosis of the
central nervous system. Brain 1995;118:1051–66.
3. Koeppen AH, Dentinger MP. Brain haemosiderin and superficial
siderosis of the central nervous system. J Neuropathol Exp Neurol
1998;47:249–70.
4. Kasturagi S, Sakai T, Watanabe K, et al. An autopsy case of
idiopathic superficial hemosiderosis of the central nervous system:
a microscopic and immunohistochemical study. Clin Neuropathol
1988;7:87–92.
5. Pribitkin EA, Rondinella L, Rosenberg SI, et al. Superficial siderosis of the central nervous system: an underdiagnosed cause of
sensorineural hearing loss and ataxia. Am J Otolaryngol 1994;15:
415–8.
6. Irving RM, Graham JM. Cochlear implantation in superficial siderosis. J Laryngol Otol 1996;110:1151–3.
7. Castelli ML, Husband A. Superficial siderosis of the central nervous system: an underestimated cause of hearing loss. J Laryngol
Otol 1997;111:60–2.
8. River Y, Honigman S, Gomori JM, Reches A. Superficial hemosiderosis of the central nervous system. Move Disord 1994;9:
559–62.
9. Kumar A, Aggarwal S, Willinsky R, et al. Posterior fossa surgery:
an unusual cause of superficial siderosis. Neurosurgery 1993;32:
455–7.
10. Walshe JM. Treatment of Wilson’s disease with trientine (triethylene tetramine) dihydrochloride. Lancet 1982;1:643–7.

Otology & Neurotology, Vol. 24, No. 1, 2003