Access: Large bore IV (at least 2), arterial line, bladder catheter (airway intubation if unable to protect airway), and nasogastric tube if intubated.

Blood pressure control (labetolol or nipride) with goal of normotension for age.

ICP intracranial pressure control—external ventricular drain if hydrocephalus (NB; avoid overdrainage of cerebrospinal fluid (CSF) to prevent rerupture, often no more than 5 cc at a time), head of bed (HOB) elevated.

Antiepileptic medication if concern for seizure.

As previously discussed, nonemergent management varies greatly depending on presentation. In elective cases, preoperative labs and imaging are needed. For the patient with a hemorrhage but minimal deficits, admission to the intensive care unit for blood pressure control and preoperative imaging studies are the two important interventions. (Emergent management is detailed above.)

In addition to the steps noted in the stabilization section, the operating room should be notified to prepare for surgery. Equipment should include the operating microscope, multiple suctions, bipolar electrocautery, an array of AVM/aneurysm clips, a craniotome (drill), and a retraction system.

Anesthesia should be consulted and appropriate measures made to ensure that multiple large bore IV access is present and adequate blood products are in the room.

It is helpful to have the microscope draped and clips prepared prior to starting the case if possible, so that quick access can be obtained should unexpected bleeding occur during opening (Fig. 8.3).

Many patients will be asymptomatic on examination. However, a detailed neurologic examination and history are always important. Attention should be paid to evidence of neurologic dysfunction in the history (see list below).

Standard preoperative laboratory studies (CBC, clotting times (PT/PTT), T&C for blood bank, chemistry panel (Chem 7)).

CT: If a child presents with a hemorrhage without a clear etiology on initial evaluation, AVM should be considered and repeat imaging in 4–6 weeks with MRI should be performed to evaluate the hemorrhage cavity after the clot has cleared .

AVM typically appears as a heterogeneous area of mixed density with serpiginous areas of enhancement after infusion of contrast material. Cerebral atrophy may sometimes be seen on the affected side. A large malformation or an intracerebral hematoma may distort the normal intracranial anatomy.

MRI is useful for 3D anatomy and identification of chronic ischemia, presumably a result of “steal” phenomena; AVM may be identified on MRI as bright signal of the surrounding brain on FLAIR or T2 images (Fig. 8.1).

The typical MRI appearance is that of a latticework of signal-void spaces, highly contrasted against surrounding cerebral tissue on both T1- and T2-weighted sequences, intermixed with regions of various signal intensities corresponding to blood products in different stages of evolution, and occasionally calcium and hemosiderin [23, 24]. The serpiginous shape of vessels may be distinctive, identified as flow-voids, and relevant anatomy can be well visualized with MR angiography. Susceptibility imaging will sometimes disclose evidence of previous hemorrhage as a dark “bloom” around the nidus [25]. Chronic ischemic changes, presumably a result of “steal” phenomenon or venous hypertension, may be identified on MRI as bright signal of the surrounding brain on FLAIR or T2 images.

Digital subtraction angiography is the definitive investigation. It establishes the nature and extent of the lesion to its blood supply and its venous drainage [26] (Fig. 8.2). Angiography entails bilateral injection of all potential arterial sources of supply to the AVM, both pial and dural (with 15 % of cerebral AVMs receiving some blood supply from ipsilateral or contralateral meningeal arteries [27]): typically at least the internal carotid arteries bilaterally, as well as the ipsilateral external carotid and vertebral arteries. Three-dimensional angiography with computer-generated reconstruction is increasingly employed to depict lesional anatomy. The typical angiographic appearance of an AVM is that of distended, tortuous afferent, and efferent vessels connecting with a tangled vascular mass, through which the circulation time is rapid; i.e., arteriovenous shunting. Other vessels or structures are not displaced unless there is an intracerebral hematoma, which appears as an avascular mass.

A recent analysis of 241 consecutive pediatric patients revealed a 0 % complication rate during the procedure and a 0.4 % post-procedural complication rate. Evaluation should look for:

Screening is not justified in the general population. Patients with HHT may be candidates for MRI/A studies of the CNS during childhood to screen for AVMs, as they may be present in 5–10 % of children with HHT.

A primary surgical principle for AVM resection is the obliteration of feeding arteries before occlusion of draining veins, as premature closure of outflow can lead to AVM rupture with uncontrolled bleeding.

AVMs are often wedge or cone shaped, and resection can be performed in a circumferential pattern, staying close to—but not entering—the nidus. It is helpful to try to maintain an even depth of resection around the lesion to avoid getting in a “hole” and caution must be taken to minimize retraction on draining vessels during dissection.

Repeated inspection of the surrounding brain for swelling or bleeding can aid the surgeon in preventing complications by early identification of poorly placed retractors or clips (Fig. 8.3).

AVM vessels may coagulate poorly and consideration should be given to clip application or gentle tamponade (if the bleeding is of small volume) if bipolar electrocautery is not working. Every attempt should be made to avoid operating within the nidus itself.