4 Multiple Burr Holes

10.1055/b-0039-172618

4 Multiple Burr Holes

Thomas Blauwblomme, Philippe Meyer, and Christian Sainte-Rose

Abstract

Thirty years after its princeps description, multiple burr hole surgery is yet not recognized as a first-line revascularization procedure in moyamoya angiopathy. Here, we describe the indications, technique, and pitfalls, emphasizing pediatrics patients. Complication rate of this indirect procedure is remarkably low, and efficacy to restore cerebral blood flow, as assessed by imaging and clinical outcome, is at least comparable to other indirect techniques in children.

4.1 History and Initial Description

Using cranial burr holes for cerebral revascularization is the consequence of serendipity more than a Cartesian, scientific approach. Spontaneous neovascularization through a burr hole in a child with moyamoya was first observed by Endo et al in 1984. ¹ A 10-year-old boy with intraventricular hemorrhage was treated with two frontal external ventricular drains. Bilateral encephalo-myo-synangiosis (EMS) was performed 3 months later, and postoperative digital subtraction angiography (DSA) showed marked bilateral neovascularization through the burr holes. This single “burr-hole” technique was therefore performed in five other pediatric cases along with EMS, with excellent clinical and angiographic results. ¹

Seven years after this princeps publication, Kawaguchi et al published their experience with multiple burr holes, as the sole revascularization supply in a series of 10 adult patients with moyamoya. ² One to four burr holes were drilled on each hemisphere, bilaterally in 8 out of 10 cases. Neovascularization was found in 41/43 burr holes on postoperative angiography performed 3 to 23 months after surgery, along with improvement in cerebral hemodynamics on SPECT studies, and cessation of transient ischemic attacks (TIAs) in 6/6 patients with preoperative ischemic attacks.

Eight years later, results of indirect cerebral revascularization with multiple burr holes were reported in a pediatric series of 14 children. ³ The authors increased the number of burr holes to cover the entire cranial vault, through 10 to 24 holes per case. Excellent clinical outcome was observed after surgery, as no child suffered from recurrent ischemic strokes. Postoperative angiography showed good neo vascularization, and the complication rate was low.

Since these pioneer studies, and despite good results, multiple burr holes were rarely reported in the literature, ⁴ and this procedure is more considered as a salvage procedure, or as an adjunct to other direct or indirect techniques. ⁵

4.2 Indications

There is currently no class A-B evidence in the literature to demonstrate the superiority of direct revascularization on indirect revascularization in pediatric moyamoya. Among indirect revascularization procedures, outcome is comparable between EMS, encephalo-duro-arterio-synangiosis, and burr holes as more than 85% of children are stroke free after surgery.

In our pediatric neurosurgical department, Necker–Enfant Malades in Paris, multiple burr hole surgery is the first-line surgical option for pediatric moyamoya angiopathy. We choose this approach regardless of the underlying etiology, age of the patient, or modality of revelation of the disease.

4.3 Key Principles

Although no basic science research has demonstrated how pial anastomosis occur in multiple burr hole surgery, vasculogenesis and angiogenesis are believed to occur at each burr hole because of chronic brain ischemia and vascular growth factor secretion. The principle of the technique is to facilitate the communication between the external (donor) and internal carotid (recipient) arteries systems through bone and meningeal opening. Increasing the number of burr holes increases the surface of brain to be revascularized, in particular the junctional areas (PCA/MCA or ACA/MCA) in the frontal poles, near the midline and parietoccipital area.

4.4 SWOT Analysis

4.4.1 Strengths

This surgical technique is simple and safe. It does not require transient clipping of the arterial vessels, as needed in bypass surgery, and there is no cosmetic defect associated to temporalis muscle transposition, as with EMS or EDAMS. The complication rate is very low, as we report no permanent neurological deficit or death related to the procedure in our cohort of 64 operated children (transient subcutaneous effusion, n = 5; meningitis, n = 1; superficial skin infection, n = 1).

This approach allows extensive revascularization of the hemispheres. Indeed, burr holes can be placed all over the cranial vault, and revascularization of the frontal pole, occipital lobe, and junctional areas is therefore possible.

Bilateral revascularization is easy during the same procedure, through a unique cosmetic incision, without increasing the morbidity related to the surgery.

This technique does not preclude further revascularization in case of stroke relapse, as the superficial temporal artery (STA) is respected, and other indirect (burr holes, EMS, EDAMS, omentum transposition) and direct techniques (STA–MCA bypass) can be performed despite the initial procedure.

4.4.2 Weakness

Multiple burr hole surgery is an indirect technique and, as such, revascularization is efficient only a few weeks after the surgery. Therefore, patients with frequent TIAs may undergo ischemic events during the postoperative period. In our cohort of 64 patients, 4 patients had TIAs that resolved spontaneously after a mean delay of 79 days.

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