March 8, 2018
A 76-year-old man with myoclonus of the left upper limb, floating left hemiparesis, and altered state of consciousness. The patient had undergone a carotid endarterectomy 7 days before the onset of symptoms.
Cerebral Hyperperfusion Syndrome
- Background:
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Carotid endarterectomy and carotid artery stenting are the standard therapies for the prevention of stroke in patients with significant carotid artery disease.
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Cerebral hyperperfusion syndrome is a rare complication that may occur following either technique.
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This syndrome can develop at any time, from immediately after surgery to up to a month later.
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The causes appear to be impaired cerebral autoregulation and postoperatively elevated systemic blood pressure.
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- Clinical Presentation:
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Clinical triad of ipsilateral headache, seizure, and focal neurologic symptoms occurring in the absence of cerebral ischemia
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- Key Diagnostic Features:
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MRI usually shows no evidence of ischemia (no restricted diffusion), accompanied by increased CBF.
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There are reports of prolongation or reduction of the MTT in the perfusion study (CBV may also be slightly increased).
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In some patients, there is evidence of cerebral edema (sulcal effacement on plain CT and hypersignal on T2 and FLAIR MRI sequences).
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Focal infarction and hemorrhage may also occur.
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Normal findings on MRI and CT do not exclude the presence of cerebral hyperperfusion syndrome, which is defined by the triad of symptoms listed above with imaging findings of augmented CBF in MRI, CT, or SPECT perfusion studies (more probable if CBF values in the revascularized territory increase by 100% or more with respect to the baseline values).
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- Differential Diagnoses:
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Stroke: most likely cause of acute symptoms in patients post-carotid endarterectomy/carotid artery stenting, usually with restricted diffusion in the DWI study and evidence of hypoperfusion in the perfusion studies; prolonged MTT with decreased CBF
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Cortical regional hyperperfusion in nonconvulsive status epilepticus: the perfusion study usually shows increased CBV and CBF with decreased MTT
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Seizure: perfusion studies after seizures usually show hypoperfusion, but there are reports of patterns of hyperperfusion and isolated increased MTT
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Hemiplegic migraine: can be associated with hyperperfusion
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- Treatment:
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Due to the rarity of this complication, there are no data from randomized trials comparing the management protocol for patients with cerebral hyperperfusion syndrome.
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Prevention is critical and is based on the recognition of vulnerable patients at risk and postoperative blood pressure control. Patients subjected to a carotid endarterectomy can do a perfusion study by CT or MRI to assess cerebrovascular reactivity.
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Findings of decreased CBF together with MTT prolongation and a slight increase in CBV indicate that blood vessels are dilated, thus confirming that the autoregulation mechanism is impaired and a cerebral hyperperfusion syndrome may happen after the procedure.
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