Cerebral revascularization (CR) remained an essential technique to restore cerebral blood flow for symptomatic hemisphere with misery perfusion (SHMP), aiming at precaution of forthcoming ischemia. Herein, we report a middle-aged gentleman presented with severe dizziness for couple years. His left carotid bifurcation and proximal middle cerebral artery (MCA) was severely stenosed (Fig. 1). The first attempt of left carotid endarterectomy was performed while ischemic symptoms and hemispheric hypoperfusion remained. His misery perfusion progressed even prescribed with dual antiplatelet therapy for nearly a year. As a result of worsening feeling of dizziness, the patent returned to our clinic for re-assessment of intracranial vasculatures. His MCA was totally OCCLUDED when admitted and the condition of left hypo-perfusion get even worse (Fig. 2). Therefore, the left misery perfusion was fixed with combined superficial temporal artery (STA)-to-MCA anastomosis and double-barrel STA synangiosis. We employed tentative clamping method (TCM) at pre-anastomosis stage, under the supervision neuro-monitoring equipment.

Fig. 1
figure 1

Preoperative sagittal view of cervical CTA (A) and axial post-contrast T1-weighted VWI (B) revealing atherosclerotic stenosis of left carotid bifurcation (arrow). Preoperative CTP (C) demonstrated misery perfusion of left temporo-parietal region. Coronal view of intracranial CTA (D) showing severe stenosis of distal portion of left M1 (arrow). Postoperative sagittal view of cervical CTA (E) confirmed reopening of carotid bifurcation (arrow) and calcified atheroma was visualized within pathological specimen (F). At 4-month follow-up, the left cortical hypo-perfusion status remained on postoperative CTP (G); Coronal view of intracranial CTA (H) revealed silent condition of left distal M1 (arrow). CTA, computed tomography angiography; CTP, computed tomography perfusion; M1, sphenoidal segment of middle cerebral artery; MCA, middle cerebral artery; VWI, vessel wall image;

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Fig. 2
figure 2

The coronal view of intracranial CTA (A) displaying proximal occlusion (blue arrow) and distal severe stenosis (yellow arrow) of left M1. Coronal pre-contrast T1-weighted VWI (D) showing eccentric wall thickening that was compatible with intracranial atherosclerosis. CTP (B, C, E, F) illustrated progressive hypo-perfusion of frontal and temporo-parieto-occipital region. CTA, computed tomography angiography; CTP, computed tomography perfusion; M1, sphenoidal segment of middle cerebral artery; VWI, vessel wall image;

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Relevant surgical anatomy

Superficial temporal artery (STA)

STA, a terminal part of external carotid artery, provide blood supply to the frontotemporal scalp and face [4]. It runs on the galea medial to the temporal line and temporoparietal fascia lateral to the superior temporal line. The mean diameter of STA was 1.5 mm and, in most cases, divided into frontal and temporal branch. Approximate 80% of STA bifurcation located superior to the zygoma and one ninth on the level of zygomatic arch.[5]

Cortical branches of middle cerebral artery (MCA)

A total of 12 branches arising from MCA have been identified from the academic studies.[3] While in the community of bypass surgery, those alternative recipient vasculatures surrounding Sylvian fissure, from above to below, included anteior parietal artery (APA), posterior parietal artery (PPA), angular artery (AA), temporo-occipital artery (TOA), posterior temporal artery (PTA), middle temporal artery (MTA).

Description of the technique

Stage1: Surgical field preparation

A “Y” shape skin incision was made to harvest both branches of STA referring to 3D reconstruction of pre-operative CTA (Fig. 3A-3C). From the beginning, 3D Robotic-guided Exoscope (AEOS, Aesculap Inc, Tuttlingen, Germany) was brought into surgical field. Bipolar cutting method (BCM) was routinely performed to dissect STA in bloodless fashion by using disposable forceps (HN-160W 0.2 ZZZII; BHSTD Co. Ltd, Beijing, China).[1, 6] (Video 00:24–00:48) Then the frontal branch was ligated, cut and temporarily clipped. Burr holes were made at entry point of STA trunk and posterior portion of external pterion, for the preservation of middle meningeal artery.[2] Dura was opened in a curvelinear manner following tenting sutures.

Fig. 3
figure 3

Lateral (A) and surgical (B) view of pre-operative 3D reconstruction CTA delineated course and location of bifurcated STA. Intraoperative picture (C) showing a “Y” shape skin incision was made to effectively harvest both branches. Lateral view of postoperative 3D reconstruction CTA (D) showing the contour of STA. Coronal view of CTA confirmed patent status of main-frontal (red dotted line, E) and main-parietal (yellow dotted line, E) STA crossing the craniotomy defect. Robust inflow flushed into MCA territory (red dotted line, F) via anastomosis site (black arrow, E/F). CTA, computed tomography angiography; MCA, middle cerebral artery; STA, superficial temporal artery;

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Stage 2: Tentative clamping method (TCM)

Before preparation of donor vessel (frontal STA), arachnoid membranes lie above cortical arteries were expensively dissected. Recipient artery, in this case, the posterior parietal artery (PPA) was chosen and dissected from cortex. Then two temporary clips were applied to carry out tentative trapping of recipient alternative at pre-anastomosis stage. At the same time, the amplitude of motor-evoked potential (MEP) and somatosensory evoked potential (SSEP) was meticulously surveillant for 20 min, during which time the whole anastomosis process can be finished. If signal drop or a decrease (50% loss of amplitude) was observed during tentative trapping period, other alternatives were prepared including angular/temporo-occipital/posterior temporal/middle temporal artery. In this case, PPA was tolerated well and utilized as recipient.

Stage 3: Cerebral revascularization

Next, the fascia and adventitia of donor was peel off. Pre-anastomosis indocyanine green (ICG) was injected to confirm blood flow direction, from cortical to insular MCA or vice verse. An oblique transection was made at trimmed edge of frontal STA for providing antegrade augmented cortical perfusion. Anchoring “heel” and “toe” sutures were initially carried out followed by recipient PPA was reclamped and opened. Then STA-PPA anastomosis was employed by 10–0 nylon thread in an interrupted fashion from the front to back wall. After all temporary clamps releasing, post-anastomosis ICG revealed patent bypass status.

Temporary clamping of temporal recipients (temporo-occipital/posterior temporal) was attempted for second site anastomosis. The amplitude, however, dropped immediately. Therefore, the distal end of parietal branch was preserved and encephalo-duro-arterio-synangiosis was used for indirect flow augmentation.

Stage 4: Closure

Dura was partially approximated and bone flap was replaced in standard fashion. Temporalis and fascia was fixed in layer-by-layer fashion. Dermal repair was carried out by 6–0 polypropylene (Prolene 6/0; Ethicon Inc., Somerville, NJ, USA).

Stage 5: Postoperative course

The patient come out of anesthesia well without new neurological deficits. Postoperative CTP (Fig. 4) demonstrated prominent amelioration of left misery perfusion. Meanwhile, his ischemic symptoms and neuro-cognitive scores were also improved.

Fig. 4
figure 4

Preoperative CTP (A, B) showing decreased CBV/CBF and increased MTT/TTP in the territory of anterior circulation, indicating hypoperfused status of left hemisphere. Postoperative CTP (C, D) demonstrated an increase in CBV/CBF with mild decrease in MTT/TTP. CTP, computed tomography perfusion; CBF, cerebral blood flow; CBV, cerebral blood volume; MTT, mean transit time; TTP, time to peak;

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Indications

Intracranial steno-occlusive vasculopathy.

  • Failure of dual-platelet medication.

  • Severe stenosis or occlusion of MCA of internal carotid artery.

  • Symptomatic with misery perfusion.

Moyamoya vasculopathy.

Hemorrhagic type in adult.

Limitations

Surgical duration may extend 20–30 min when applying tentative clamping method.

How to avoid complications

Cerebral Angiography was high recommended at preoperative stage for appraisal of hemispheric collaterals.

Bony Burr holes should be made sparing pterion to avoid unexpected silent infarction with sacrifice of external collaterals (eg. frontal branch of MMA).

Tentative clamping of recipient alternatives must be applied to avoid iatrogenic cerebral ischemia.

MEP and SSEP was employed to monitor underlying risks of hemispheric hypoperfusion, which may be resolved by systolic pressure elevation in real time fashion, to avoid ischemic complications.

The non-absorbable polypropylene was utilized to achieve plastic repair of incision avoiding scalp necrosis.

Specific perioperative considerations

Peri-operative workup.

Cerebral and cervical CT angiography (pre-op & post-op with 24 h).

Brain CT perfusion (pre-op & post-op with 24 h).

High-resolution brain MRI (ONLY pre-op).

Conventional brain MRI (pre-op & post-op within 24 h).

Cerebral Angiography (ONLY pre-op).

Neuro-cognitive scales (pre-op & post-op within 7 days).

Instructions for post-operative care.

Intensive monitoring in ICU on the surgical day.

Antiplatelet therapy begin at post-op day 1.

Specific information to give to the patient about surgery & potential risks

Following combined bypass, cortical hypoperfusion condition was resolved while the risk of hyperperfusion or intracranial hemorrhage may increase. Systolic pressure was treated at or below preoperative baseline. If headache, seizure or new-onset of neurological deficits encountered, emergent CT and repeated CTP findings were checked to rule out hematoma and hyperperfusion.