Elsevier

Journal of Clinical Neuroscience

Volume 43, September 2017, Pages 146-148
Journal of Clinical Neuroscience

Case report
Reversible hemispheric hypoperfusion in two cases of SMART syndrome

https://doi.org/10.1016/j.jocn.2017.05.013Get rights and content

Highlights

  • CT perfusion in SMART syndrome may demonstrate significant reversible hemispheric hypoperfusion.

  • Prolonged clinical deficits may be due to impaired cerebrovascular autoregulation.

  • L-arginine may be a potential therapy for impaired vascular autoregulation.

Abstract

Stroke-like migraine attacks after radiation therapy (SMART) syndrome manifests as prolonged episodes of cortical dysfunction, years after cranial irradiation. We present two cases demonstrating reversible hemispheric hypoperfusion. Case 1 presented with left hemispheric symptoms following previous similar episodes. CT perfusion (CTP) demonstrated reversible hemispheric hypoperfusion; subsequent investigations were consistent with SMART syndrome. Case 2 presented following the third episode of a hemispheric syndrome with near-identical CTP abnormalities. L-arginine was administered with rapid reversal of clinical and CTP abnormalities. We conclude that SMART syndrome may demonstrate significant hypoperfusion on hyperacute CTP without subsequent infarction. Impaired cerebrovascular autoregulation probably contributes to cortical dysfunction in SMART syndrome. L-arginine warrants investigation as a potential treatment.

Section snippets

Case 1

A 52-year-old man presented with headache, dysphasia, right hemiparesis and right homonymous hemianopia. Quantitative CTP was performed using automated RAPID quantification of ‘core infarct’ (relative cerebral blood flow <30% of contralateral hemisphere) and penumbra (Tmax >6 s) with a Siemens Definition AS+ scanner (69 mm coverage with 30 acquisitions over 60 s [1].) It demonstrated large volume left hemispheric hypoperfusion (Fig. 1A) with core infarct calculated at 11 mL and penumbra >70 mL,

Case 2

A 75-year-old man developed acute-onset dysphasia, right hemianopia, hemisensory inattention and headache. Quantitative CTP (as above but with 96 mm coverage) demonstrated left hemispheric hypoperfusion, near-identical to Case 1 (Fig. 3A). CTA showed no carotid territory steno-occlusive disease. Two similar episodes occurred in the six months prior, without restricted diffusion on MRI. Four years prior, he had received radiotherapy for a single cerebral metastasis (non-small cell lung cancer).

Discussion

The precise pathophysiology of SMART syndrome is unknown; radiation-induced cortical hyperexcitability analogous to hemiplegic migraine has been proposed [4]. Our cases demonstrate that hemispheric cerebral ischaemia occurs hyper-acutely in SMART syndrome and is fully reversible. In both cases, substantial volumes of tissue reached ‘penumbral’ hypoperfusion thresholds [2], suggesting impaired cerebrovascular autoregulation as a contributor to prolonged cortical dysfunction in SMART syndrome.

Conflict of interest statement

On behalf of all authors, the corresponding author states that there is no conflict of interest.

Acknowledgements

Nil.

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