Pediatric emergency medicine trisk 1002

architectural features include exact anatomic relationships of the nidus,
feeding arteries, and draining veins as well as topographic relationships
between AVM and adjacent brain. MRI is sensitive in revealing subacute
hemorrhage. The AVM appears as a sponge-like structure with patchy
signal loss, or flow voids, associated with feeding arteries or draining veins
on T1-weighted sequences ( Fig. 122.3 ). MRI and MRA in combination
provide complementary information that facilitates understanding the threedimensional structure of the nidus, feeding arteries, and draining veins.
MRA currently cannot replace conventional cerebral angiography. In the
case of acute hemorrhage, the hematoma obscures all details of the AVM
making MRA virtually useless. This calls for direct use of cerebral
angiography if the characteristics of the hematoma strongly suggest AVM
as an etiology.


FIGURE 122.2 Coronal CT of the brain demonstrates intraventricular hemorrhage with
communicating hydrocephalus with minimal interval increase in the ventricular
dilatation. Diffuse cerebral edema with narrowing of the CSF space is suggestive of
increased intracranial pressure.


FIGURE 122.3 T1-weighted sagittal MRI demonstrates an AVM in the right corpus
callosum with intraventricular hemorrhage with main feeding vessel from right
pericallosal artery and draining into the right internal cerebral vein.

Management. The currently used treatments for AVMs include: (1)
Microsurgical resection only, (2) preoperative endovascular embolization
followed by microsurgical resection, (3) stereotactic radiosurgery only, (4)
preprocedural endovascular embolization followed by radiosurgical
treatment, (5) endovascular embolization only, and (6) observation only.
The ultimate goal for all of these modalities is cure for the patient; however,
the only way to achieve cure is with complete obliteration of the AVM.

Microsurgery is the gold standard for resection of small superficial AVMs
that other methods of treatment must be measured against. There is


certainly a well-established role for adjunctive endovascular embolization
of some AVMs. Clearly, there are specific situations, such as small deep
AVMs in eloquent brain structures, where microsurgery should not be used
as the primary treatment modality; stereotactic radiosurgery and
occasionally embolization (when there is reasonable expectation of
complete obliteration by embolization) are the preferred treatment options
in these cases. We also make a case for observation in patients with large
AVMs in or near critical areas of the brain that are not ideal for surgical
resection or radiosurgery. Here, the pursuit of treatment may actually be
more harmful to the patient than the natural history of the AVM.
Indications for Surgical Resection. There are several clear indications for
microsurgical resection of AVMs. AVMs with Spetzler–Martin grades I to
III on the convexity should generally be resected. The Spetzler–Martin
grading system takes into account three factors that greatly affect the
surgical resectability of the AVM: size (<3 cm, 1 point; 3 to 6 cm, 2 points;
>6 cm, 3 points), location (noneloquent cortex, 0 points; eloquent cortex, 1
point), and venous drainage (superficial only, 0 points; deep, 1 point).
Patients with AVMs that present with major hemorrhage, progressive
neurologic deterioration, inadequately controlled seizures, intractable
headache, or venous restrictive disease should be strongly considered for
surgical intervention, including resection, hematoma evacuation, or acute
spinal fluid diversion.
Cerebellar and pial brainstem AVMs should also be given strong
consideration for surgical resection to prevent the higher risk of bleeding as
compared to supratentorial AVMs. Some basal ganglia and thalamic AVMs
should be surgically resected, as they carry a considerably higher annual

bleed rate of 11.4%; in addition, morbidity and mortality with each bleed in
these locations reach 7.1% and 42.9%, respectively (again, in contrast to the
overall mortality rate of AVM hemorrhage of 10%).
Hence, one may justify a more aggressive approach for surgical treatment
in younger patients as their cumulative risk of hemorrhage is so high. In
addition, neurologic deficit caused at a young age is generally better
tolerated and has a greater chance of recovery.

ACUTE HYDROCEPHALUS