Reply

Dear sir We reported a case of recurrent thunderclap headache associated with angiographically documented reversible segmental intracerebral vasospasm occurring without underlying intracranial pathology. Severe intermittent headaches recurred for 14 days prior to the development of persisting cortical blindness, dysphasia and visuospatial deficits accompanied by bilateral watershed cerebral infarction on neuroimaging. Whilst there are similarities between the clinical features of this case and those described in the ‘posterior leukoencephalopathy syndrome’ (PLES), we believe there are differences which make this diagnosis less likely.

In our case there was a long latency between the explosive onset of symptoms and the development of neurological signs (15 days) and magnetic resonance brain imaging was normal on day 12. PLES is associated with the acute or subacute onset of symptoms with radiological abnormalities usually evident on presentation. PLES is associated with eclampsia, immunosuppressant agents, or more frequently with abrupt elevations in blood pressure which are usually severe but can be moderate. Our patient's blood pressure fluctuated throughout the illness but did not exceed 170/90 and on development of focal neurological signs was 130/70.

The most striking radiological feature of this case was the persistent and severe vasospasm seen on angiography. Vasospasm has been postulated as a mechanism for PLES but has not been described in patients with this entity. Whilst our patient made some clinical improvement and the vasospasm eventually resolved, the abnormalities on MRI which involved both white matter and cortex did not improve and were consistent with bilateral watershed infarction. The angiographic appearances of vasospasm can be difficult to differentiate from vasculitis and therefore if clinical deterioration continues brain biopsy should be considered.