Unusual Complication of Carotid Stenting Delayed Hyperperfusion Syndrome

Abstract

Cerebral hyperperfusion syndrome (CHS) is a rare syndrome, occurring in three situations: in hypertensive encephalopathy, preeclampsia-eclampsia, and after carotid reperfusion procedures (carotid endarterectomy, carotid artery stenting [CAS]). CHS secondary to carotid revascularization presents with severe ipsilateral headache, seizures, focal neurological deficits, and occasionally intracerebral hemorrhage. A 65-year-old man underwent a right-sided carotid artery procedure and was asymptomatic postprocedure; his blood pressure was controlled. After 2 weeks of the procedure, the patient developed left focal seizures with secondary generalization. His brain magnetic resonance imaging (MRI) showed right temporo-parietal FLAIR hyperintensities without corresponding diffusion restriction or hemorrhage suggestive of edema. He is diagnosed with CHS. Repeat MRI of the brain after 2 months shows resolution of changes. CHS commonly occurs in the 1^st week of carotid revascularization. Our patient presented after 2 weeks. We should be careful about this complication beyond the early days after the reperfusion procedure.

INTRODUCTION

Cerebral hyperperfusion syndrome (CHS) is characterized by excessive cerebral blood flow. Increased cerebral blood flow with impaired autoregulation is the primary mechanism. CHS postcarotid procedure manifests as unilateral headache, seizure, focal neurologic defects, and intracerebral hemorrhage in the severe form.[1] CHS commonly occurs within 1 week of the procedure.[2] Delayed occurrence after 1 week is rare. Our patient had delayed CHS after 2 weeks.

CASE REPORT

A 65-year-old right-handed male had an acute onset of left hemiparesis and dysarthria. He had diabetes and hypertension. His magnetic resonance imaging (MRI) of the brain and magnetic resonance angiography (MRA) of the brain and neck shows watershed infarct in the right hemisphere [Figure 1]. MRA shows 90% internal carotid stenosis at the bifurcation on the left side and 70% on the right at the same level [Figure 2]. He had a good recovery over the next 2 weeks and underwent planned left carotid stenting [Figure 3]. The procedure was uneventful. His blood pressure was monitored and was well controlled.

Figure 1.

Magnetic resonance imaging brain DWI image showing ACA-MCA and MCA-PCA right hemispheric watershed infarct

Figure 2.

Magnetic resonance angiography image showing significant bilateral carotid bifurcation stenosis, more on right than left

Figure 3.

Digital substraction angiography showing pre- and postright carotid stenting images

The patient was discharged after 3 days of observation. Fifteen days after the procedure, the patient developed left focal motor seizures with secondary generalization. He was readmitted emergently. He received lorazepam and started on levetiracetam. Immediately after the seizure, his blood pressure was 180/100, probably reactionary. Once seizures were controlled and the patient stabilized, blood pressure was 140/80. An MRI of the brain was done to rule out the recurrence of the stroke. There was a fluid attenuated inversion recovery (FLAIR) hyperintense lesion in the parietotemporal region with no corresponding diffusion-restricted lesion [Figures 4 and 5]. After the patient became conscious and oriented, he was reexamined. We found the left hemianopia was probably due to involvement of the optic radiation. All limb power was normal. We diagnosed him with hyperperfusion syndrome. We monitored blood pressure and maintained it below 120/70. His hemianopia completely recovered in 3 days. The patient was clinically stable without further deficit. His repeat MRI brain after 2 months showed resolution of MRI changes [Figure 6].

Figure 4.

Magnetic resonance imaging brain FLAIR image hyperintense lesion in right parietotemporal region

Figure 5.

Magnetic resonance imaging brain DWI image not showing true diffusion restriction in right parietotemporal region

Figure 6.

Magnetic resonance imaging brain FLAIR image after 2 months showing complete resolution of lesion

DISCUSSION

Hyperperfusion syndrome is a group of disorders. Hyperperfusion syndrome occurs in hypertensive encephalopathy, eclampsia, and after carotid revascularization procedures (carotid endarterectomy [CEA] or carotid artery stenting [CAS]).[3]

Cerebral blood flow is usually well maintained due to autoregulation. CHS, secondary to reperfusion procedures (CEA/CAS), involves the following mechanisms. One, prolonged hypoperfusion due to stenosis may lead to abnormality of cerebral vascular autoregulation.[4,5] Chronic low flow leads to resistance arterioles adaptive changes, causing autoregulatory capacity loss. These changes in arterioles lower the limit at which autoregulatory breakdown occurs and increase the risk of focal hyperperfusion after reperfusion procedures. Systemic hypertension will increase the risk of CHS, but even without systemic hypertension, the normalized inflow to already hypoperfused vessels may cause the breakdown of autoregulation at a low level of mean arterial pressure. Vasogenic edema occurs due to a breakdown in autoregulation resulting from excessive focal cerebral blood flow. Second, systemic hypertension secondary to the affection of baroreceptors during procedures (CAS/CEA), leading to intense cerebral blood flow and hyperperfusion syndrome.[1] Increased regional cerebral blood flow can be documented with transcranial Doppler, cerebral perfusion imaging such as single photon emission computed tomography, and computed tomography or MRI perfusion studies. Arterial spin labeling, an MRI technique, can estimate cerebral blood flow without a contrast agent. We have not done any of these studies on our patients. Risk factors for CHS are diabetes mellitus, old age, recent contralateral CEA, postinterventional hypertension, contralateral carotid occlusion, intra-interventional ischemia, and administration of anticoagulants or antiplatelet agents.[2,6] Risk factors in our patient were diabetes mellitus, old age, contralateral carotid stenosis, and antiplatelet use. Our patient had no intrainterventional ischemia; his blood pressure was well controlled.

The most common clinical presentations in a review include severe headache (ipsilateral to the lesion side or diffuse) and eye and facial pain. Less frequent and more severe symptoms include focal neurological deficits, seizures, and loss of consciousness. Our patient had headaches, seizures, and hemianopia. CHS occurred earlier after CAS than after CEA. The reason for this difference is not apparent. The incidence of CHS peaks at 12 h after CAS.[7] However, our patient had CHS at 2 weeks.

The exact causes for the delayed presentation of CHS are not known. For prevention, the best we can do is blood pressure monitoring and control. Once CHS sets in, the goal of treatment is to avoid complications and provide the best supportive care. Cerebral edema, seizures, and hemorrhage are the main causes of neurological deterioration. Anti-edema measures like hyperventilation, mannitol, or hypertonic saline are used. Antiseizure agents are commonly given.

CONCLUSIONS

CHS is an uncommon complication. It usually develops in the 1^st week of CAS or CEA due to breakdown of cerebral autoregulation. The exact cause of delayed CHS is not known. Blood pressure control is the mainstay of treatment. We should be vigilant for this rare delayed complication of carotid reperfusion.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.