A DIFFICULT CASE

Superficial siderosis following spontaneous intracranial hypotension Alastair J S Webb,1,2 Enrico Flossmann,1,2 Richard J E Armstrong1,2

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Department of Clinical Neurosciences, University of Oxford, Oxford, UK 2 Department of Neurology, Royal Berkshire Hospital, Reading, UK Correspondence to Dr Alastair Webb, Department of Clinical Neuroscience, Level 6, West Wing, University of Oxford, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK; [email protected] Accepted 31 May 2015

To cite: Webb AJS, Flossmann E, Armstrong RJE. Pract Neurol Published Online First: [ please include Day Month Year] doi:10.1136/ practneurol-2015-001169

CASE REPORT A 33-year-old man presented in 2002 with an acute, severe, occipital headache associated with nausea and photophobia, causing him to collapse to the pavement; there was no persisting neurological impairment. He had mild hypertension, hypercholesterolaemia and asthma, but took no regular medication. His initial neurological examination was normal. A CT scan of head was normal but cerebrospinal fluid (CSF) showed xanthochromia, but was otherwise normal. A four-vessel digital subtraction cerebral angiogram was normal. He took nimodipine for 3 weeks and was discharged. He subsequently developed recurrent left-sided headaches, each lasting hours to days, with backache and dizziness, nausea and photophobia. These varied in frequency and severity but progressed over time, eventually having more days with headache than without. Following a more severe episode, he required hospital admission, with a diagnosis of migraine. In 2008, he developed neck pain with tingling in his left middle finger. An MR scan of cervical spine showed a posterior osteophytic bar with root impingement at C5/6 and C6/7. He obtained temporary relief from a nerve root blockade at both levels but eventually underwent a C5/6/7 anterior cervical decompression and fusion. In 2014, he became progressively unsteady and developed a subtle righthand tremor. One day he woke with severe headache with nausea, vomiting and photophobia, with worsened unsteadiness. On examination there was mild ataxia on tandem gait with scanning dysarthria. CT scan of head was again normal, and CSF again showed xanthochromia. Repeat cerebral CT angiogram and digital subtraction angiogram were

normal, and he was again discharged from neurosurgery on nimodipine. Over the next month, his headaches became more frequent, his gait deteriorated and he struggled to stand for long. He developed a marked action tremor of the right hand, and his memory and concentration worsened. His hearing remained normal. The headaches worsened over 2 days, and he was readmitted. Repeat CT scan of head was normal, and CSF again showed xanthochromia. A neurology opinion was sought. On reviewing the history, his headaches worsened during the day and had a postural element, improving significantly on lying flat compared with standing. Review of his medical notes showed that there had also been a significant postural element to the initial headache in 2002. On examination he had bilateral, sustained, direction-changing, gaze-evoked nystagmus with saccadic interruption of pursuit movements, mild intention tremor and gait ataxia. He had brisk, symmetrical deep tendon reflexes and a left extensor plantar response, but normal strength throughout. He had normal hearing. His MR scan of brain and spine showed T2 hypointensity around the cerebellar folia and brainstem, with ‘blooming’ on gradient-echo sequences, suggesting superficial siderosis (see figure 1). There was a ventral, extradural spinal CSF collection from C4 to T12, with two thoracic intervertebral discs impinging on the dura but not the spinal cord. In hindsight, there was a CSF collection on his preoperative MRI in 2008. A CT myelogram showed free passage of contrast into the extradural CSF collection, but did not identify the dural defect. The final diagnosis was of a spontaneous dural tear causing chronic intracranial

Webb AJS, et al. Pract Neurol 2015;0:1–3. doi:10.1136/practneurol-2015-001169

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A DIFFICULT CASE

2 Webb AJS, et al. Pract Neurol 2015;0:1–3. doi:10.1136/practneurol-2015-001169

Figure 1 (A) MR scan of brain: there is low signal on T2-weighted imaging around the brainstem and in the folia of the cerebellum (left) with blooming artefact in the cerebellar folia on the gradient-echo sequence (right). (B) MR scan of the cervical spine (T2-weighted sagittal (left) and axial (right)) showing a longitudinally extensive ventral cerebrospinal fluid (CSF) collection with CSF anterior to the dural membrane (see arrows). (C) CT myelogram shows intrathecal contrast throughout the ventral CSF collection in the cervical (upper right) and thoracic (lower right) regions, with two intervertebral discs indenting the dura but not the spinal cord.

A DIFFICULT CASE hypotension resulting in recurrent subarachnoid haemorrhage and ultimately superficial siderosis. DISCUSSION Superficial siderosis is a rare cause of dementia caused by deposition of haemosiderin in the brain and spinal cord and presenting with progressive ataxia, pyramidal signs, sensorineural hearing loss and cognitive impairment. The frequency of incidental diagnoses made at postmortem suggests that there is often an asymptomatic phase. Over 30% of patients do not have an identifiable underlying source of subarachnoid haemorrhage.1 Once established, the illness can progress despite control of the source of bleeding. However, the disability cannot stabilise unless further haemorrhage is prevented. Intracranial hypotension caused by previous surgical procedures can lead to superficial siderosis,2 although the mechanism is unclear. There are no previous reports of spontaneous intracranial hypotension causing superficial siderosis. Given the large proportion of cases of superficial siderosis with no identifiable cause,1 recognition of spontaneous intracranial hypotension as a possible cause may help to prevent recurrent haemorrhage and subsequent superficial siderosis. This man with spontaneous intracranial hypotension presented with recurrent subarachnoid haemorrhage leading to symptomatic superficial siderosis, yet we did not identify a focal bleeding source. However, the presentation suggested low-pressure headaches from the onset, with a demonstrable spinal CSF leak. The mechanism by which low CSF pressure causes chronic subarachnoid haemorrhage is uncertain. Intradural neurosurgical procedures with large volume CSF draining can give low CSF pressure and provoke remote cerebellar haemorrhage. Similarly, cerebellar haemorrhage can follow lumbar–peritoneal shunting. This clear association between CSF drainage and secondary, remote haemorrhage may result from brainstem sagging causing traction on the superior vermian veins. Previous series of patients with superficial siderosis have included a few with large extradural CSF collections after trauma or surgery, but none where spontaneous intracranial hypotension caused superficial siderosis. This suggests that some of the one-third of patients whose superficial siderosis is currently unexplained may have spontaneous intracranial hypotension. Its identification and treatment

Webb AJS, et al. Pract Neurol 2015;0:1–3. doi:10.1136/practneurol-2015-001169

by early closure of the dural insufficiency may prevent further haemorrhage and haemosiderin deposition. Although preventing recurrent haemorrhage by treating known bleeding sources does not always reduce the symptom progression in superficial siderosis, without control of bleeding the condition can only worsen. In conclusion, this was an unusual case of chronic, spontaneous intracranial hypotension resulting in recurrent subarachnoid haemorrhage and superficial siderosis, likely due to repeated traction on the superior vermian veins. In patients with recurrent subarachnoid haemorrhage without a known bleeding source, clinicians should consider intracranial hypotension as the possible cause.

Key messages ▸ Superficial siderosis is the deposition of haemosiderin over the surface of the brain resulting in ataxia, hearing loss and cognitive impairment. ▸ One-third of cases of superficial siderosis have no identifiable bleeding source. ▸ We present a case of superficial siderosis associated with a spontaneous low cerebrospinal fluid (CSF) pressure syndrome, likely due to traction on the cerebellar veins. ▸ Clinicians should consider looking for a spinal CSF collection in people with cryptogenic superficial siderosis.

Contributors AJSW cared for the patient and drafted the manuscript. RJEA and EF cared for the patient, supervised the case report and edited the manuscript. Competing interests None declared. Patient consent Obtained. Provenance and peer review Not commissioned; externally peer reviewed. This paper was reviewed by Julian Fearnley, London, UK.

REFERENCES 1 Fearnley JM, Stevens JM, Rudge P. Superficial siderosis of the central nervous system. Brain 1995;118:1051–66. 2 Kumar N, McKeon A, Rabinstein AA, et al. Superficial siderosis and CSF hypovolemia: The defect (dural) in the link. Neurology 2007;69:925–6.

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Superficial siderosis following spontaneous intracranial hypotension.

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