title: Improvement in cerebral hemodynamic parameters and outcomes after superficial temporal artery-middle cerebral artery bypass in patients with severe stenoocclusive disease of the intracranial internal carotid or middle cerebral arteries.
abstract: OBJECTIVE
  Both the older and the recent extracranial-intracranial (EC-IC) bypass trials for symptomatic carotid occlusion failed to demonstrate a reduction in stroke recurrence. However, the role of superficial temporal artery (STA)-middle cerebral artery (MCA) bypass in patients with symptomatic intracranial stenoocclusive disease has been rarely evaluated. The authors evaluated serial changes in various cerebral hemodynamic parameters in patients with severe stenoocclusive disease of the intracranial internal carotid artery (ICA) or middle cerebral artery (MCA) and impaired cerebral vasodilatory reserve (CVR), treated by STA-MCA bypass surgery or medical treatment.
  
  
  METHODS
  Patients with severe stenoocclusive disease of the intracranial ICA or MCA underwent transcranial Doppler (TCD) ultrasonography and CVR assessment using the breath-holding index (BHI). Patients with impaired BHI (< 0.69) were further evaluated with acetazolamide-challenge technitium-99m hexamethylpropyleneamine oxime ((99m)Tc HMPAO) SPECT. STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. All patients underwent TCD and SPECT at 4 ± 1 months and were followed up for cerebral ischemic events.
  
  
  RESULTS
  A total of 112 patients were included. This total included 73 men, and the mean age of the entire study population was 56 years (range 23-78 years). (99m)Tc HMPAO SPECT demonstrated impaired CVR in 77 patients (69%). Of these 77 patients, 46 underwent STA-MCA bypass while 31 received best medical treatment. TCD and acetazolamide-challenge (99m)Tc HMPAO SPECT repeated at 4 ± 1 months showed significant improvement in the STA-MCA bypass group. During a mean follow-up of 34 months (range 18-39 months), only 6 (13%) of 46 patients in the bypass group developed cerebral ischemic events, as compared with 14 (45%) of 31 patients receiving medical therapy (absolute risk reduction 32%, p = 0.008).
  
  
  CONCLUSIONS
  STA-MCA bypass surgery in carefully selected patients with symptomatic severe intracranial stenoocclusive disease of the intracranial ICA or MCA results in significant improvement in hemodynamic parameters and reduction in stroke recurrence.
authors.affiliation: Department of Surgery.
authors.forename: Shiong Wen
authors.initials: SW
authors.lastname: Low
authors.affiliation: Department of Surgery.
authors.forename: Kejia
authors.initials: K
authors.lastname: Teo
authors.affiliation: Department of Surgery.
authors.forename: Sein
authors.initials: S
authors.lastname: Lwin
authors.affiliation: Division of Neurology, and.
authors.forename: Leonard L L
authors.initials: LL
authors.lastname: Yeo
authors.affiliation: Division of Neurology, and.
authors.forename: Prakash R
authors.initials: PR
authors.lastname: Paliwal
authors.affiliation: Division of Neurology, and.
authors.forename: Aftab
authors.initials: A
authors.lastname: Ahmad
authors.affiliation: Department of Diagnostic Imaging, National University Hospital System, Singapore; and.
authors.forename: Arvind K
authors.initials: AK
authors.lastname: Sinha
authors.affiliation: Division of Neurology, and.
authors.forename: Hock Luen
authors.initials: HL
authors.lastname: Teoh
authors.affiliation: Division of Neurology, and.
authors.forename: Lily Y H
authors.initials: LY
authors.lastname: Wong
authors.affiliation: Department of Diagnostic Imaging, National University Hospital System, Singapore; and.
authors.forename: Vincent F
authors.initials: VF
authors.lastname: Chong
authors.affiliation: Division of Neurology, and.
authors.forename: Raymond C S
authors.initials: RC
authors.lastname: Seet
authors.affiliation: Division of Neurology, and.
authors.forename: Bernard P L
authors.initials: BP
authors.lastname: Chan
authors.affiliation: Department of Surgery.
authors.forename: Tseng Tsai
authors.initials: TT
authors.lastname: Yeo
authors.affiliation: Department of Surgery.
authors.forename: Ning
authors.initials: N
authors.lastname: Chou
authors.affiliation: Division of Neurology, and.|YLL School of Medicine, National University of Singapore, Singapore.
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Sharma
mesh_terms: D000328:Adult; D000368:Aged; D016893:Carotid Stenosis / Q000503:physiopathology / Q000601:surgery*; D002548:Cerebral Revascularization / Q000379:methods*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D020765:Intracranial Arterial Diseases / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D013699:Temporal Arteries / Q000601:surgery*; D016896:Treatment Outcome; D055815:Young Adult
keywords: BHI = breath-holding index; CVR = cerebral vasodilatory reserve; EC-IC = extracranial-intracranial; HMPAO = hexamethylpropyleneamine oxime; ICA = internal carotid artery; MCA = middle cerebral artery; SPECT; STA = superficial temporal artery; TCD = transcranial Doppler; acute ischemic stroke; bypass; cerebral vasodilatory reserve; external carotid-internal carotid bypass; intracranial atherosclerosis; middle cerebral artery; superficial temporal artery; vascular disorders