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Cerebral Hyperperfusion Syndrome After Superficial Temporal Artery-middle Cerebral Artery Bypass for Severe Intracranial Steno-occlusive Disease: A Case Control Study

Teo, Kejia MRCS*; Choy, David K.S. FRCS*; Lwin, Sein FRCS*; Ning, Chou FRCS*; Yeo, Tseng Tsai FRCS*; Shen, Liang PhD; Chong, Vincent F. FRCR§; Teoh, Hock L. MRCP; Seet, Raymond C. MRCP‡,‖; Chan, Bernard P.L. MD; Sharma, Arvind K. MD§; Sharma, Vijay K. MD, RVT‡,‖

doi: 10.1227/NEU.0b013e31828bb8b3
Research-Human-Clinical Studies

BACKGROUND: Intracranial stenoses carry increased risk for cerebral ischemia. We perform external carotid-internal carotid (EC-IC) artery bypass in our patients with severe stenosis of the intracranial internal carotid (ICA) or middle cerebral artery (MCA) with impaired cerebral vasodilatory reserve (CVR).

OBJECTIVE: To evaluate cerebral hemodynamics and cerebral hyperperfusion syndrome (HPS) in patients who develop focal neurological deficits after EC-IC bypass surgery.

METHODS: Patients with severe intracranial ICA or MCA stenosis and impaired CVR on transcranial Doppler (TCD) derived breath-holding index (BHI) were evaluated with acetazolamide-challenged technetium-99m hexamethylpropyleneamineoxime–single-photon emission computed tomography (SPECT). EC-IC bypass surgery was offered to patients with impaired CVR on SPECT. Close monitoring was performed in patients developing focal neurological deficits within 7 days of surgery.

RESULTS: Of 112 patients with severe intracranial ICA/MCA stenosis, 77 (69%) showed impaired CVR and 46 (41%) underwent EC-IC bypass. Transient neurological deficits within 7 days of surgery developed in 8 (17%). HPS was confirmed by CT perfusion and/or SPECT in 7 cases. A strong correlation was observed between HPS and preoperative TCD-BHI values (0%, 6.3%, and 41% in patients with BHI 0.3-0.69, 0-0.3 and <0, respectively; P = .012). HPS patients showed more than a 50% increase in MCA flow velocity on TCD (compared with preoperative values) on the operated side (63.3% vs 3.3% on control side, P < .001). Meticulous control of blood pressure and hydration led to rapid and complete resolution of neurological deficits in all cases.

CONCLUSION: Symptomatic cerebral HPS is common in the early postoperative period after EC-IC bypass surgery. Early diagnosis and appropriate management might prevent the complications of this syndrome.

ABBREVIATIONS: BHI, breath-holding index

CVR, cerebral vasodilatory reserve

EC-IC, extracranial-intracranial

99Tc HMPAO, technetium-99m hexamethylpropyleneamineoxime

HPS, hyperperfusion syndrome

ICA, intracranial internal carotid

MCA, middle cerebral artery

SPECT, single-photon emission computed tomography

STA, superficial temporal artery

TCD, transcranial Doppler

*Division of Neurosurgery, National University Hospital, Singapore;

Division of Neurology, National University Hospital, Singapore;

§Department of Diagnostic Imaging, National University Hospital, Singapore;

Yong Loo Lin School of Medicine, National University of Singapore, Singapore

Correspondence: Vijay K Sharma, MD, Division of Neurology, Department of Medicine National University Hospital Level 10, Tower Block1E Kent Ridge Rd, Singapore 119228. E-mail:

Received September 09, 2012

Accepted January 29, 2013

Copyright © by the Congress of Neurological Surgeons