Pediatric emergency medicine trisk 1001

Acute hemorrhage from a chiasmal CM is a rare cause of permanent visual loss.. The MRI appearance of CMs has been categorized into four types: a hyperintense core on T1-and T2-weighted i

aneurysms present as unruptured and incidental Most pediatric aneurysms are spontaneous, with the remainder related to high-energy head trauma causing dissection, hypertension secondary to aortic coarctation, polycystic kidney disease, Marfan syndrome, fibromuscular dysplasia, atherosclerosis, moya moya disease, or aortic hypoplasia Family history of cerebral aneurysms, alcohol or tobacco use can also play a role in pediatric cerebral aneurysms

Diagnostic Imaging Because computed tomography (CT) is noninvasive and widely available, CT angiography (CTA) has been used for the

screening and diagnosis of vascular injuries ( Fig 122.1 ) The main

disadvantage of CTA is related to bony artifact limiting its ability to identify abnormalities in some areas such as carotid canal or transverse foramina However, current scanners are capable of rendering very high–resolution images along with high-speed data acquisition

Magnetic resonance imaging (MRI) and MR angiography (MRA) offers

a high-resolution noninvasive approach for diagnosis and follow-up of vascular injuries It is helpful in visualization of the arterial wall and detection of intramural hematoma However, the accuracy of MRA is limited in detecting small intimal injuries (<25% luminal stenosis) and early pseudoaneurysm formation The resolution of MRA now approaches that of conventional angiography

Cerebral angiography remains the gold standard diagnostic modality It is currently the most accurate modality as it provides fine detail of vascular anatomy and intimal injury near bony structures such as the skull base or the transverse foramen However, due to its invasive nature and associated risk of iatrogenic injuries, it is advisable to reserve formal angiography for confirmation of findings detected on a screening diagnostic examination

FIGURE 122.1 Axial CT of the brain shows hyperdensity consistent with aneurysm

associated with acute hemorrhage in the basal cisterns The prominence of the temporal horns of the lateral ventricles is also indicative of acute hydrocephalus.

Management Spontaneous cerebral aneurysms presenting with bleeding are uncommon but should be treated because of a poor natural history Imaging should be first acquired, and only if mass effect is not detected and

a high suspicion of aneurysmal rupture still exists should a lumbar puncture

be attempted Aggressive surgical management with clipping, resection, or trapping of intracranial dissecting aneurysms by surgical or endovascular methods seems the most appropriate treatment

Cavernous Malformation

Current Evidence Cavernous malformations (CMs), also known as cavernous angiomas or cavernomas, are compact lesions comprised of sinusoidal vascular channels lined by a single layer of endothelium that lacks the full complement of mature vessel wall components Between the vascular channels in the core of the lesion, there is loose connective tissue stroma without intervening brain parenchyma The prevalence of CMs has been estimated to be between 0.4% and 0.9% of the population and 8% and 15% of all vascular malformations They present with headache, seizure, focal neurologic deficit, or as an incidental radiographic finding

The majority of CMs are located supratentorially, typically in the white matter of the cerebral hemispheres The infratentorial CMs are located in the cerebellum, pons, midbrain, and medulla Less frequent locations of CMs are the lateral and third ventricles, cranial nerves, and optic chiasm Acute hemorrhage from a chiasmal CM is a rare cause of permanent visual loss Of the extracerebral locations, the cavernous sinus, the orbits, and the spinal cord are the most common

Diagnostic Imaging CT is more sensitive at detecting CMs, but its specificity is low since most appear simply as high-density lesions (acute hemorrhage) with little or no contrast enhancement This is in contrast to the high sensitivity and specificity of MRI for CMs The MRI appearance

of CMs has been categorized into four types: a hyperintense core on T1-and T2-weighted images representing subacute hemorrhage (Type I); a

“classic” picture of mixed-signal, reticulated core surrounded by a low-signal rim (Type II); an iso- or hypointense lesion on T1 and markedly hypointense lesion with hypointense rim on T2, which corresponds to chronic hemorrhage (Type III); and punctate, poorly visualized hypointense foci, which can be visualized only on gradient echo MRI, representing tiny

CM or telangiectasia (Type IV)

Management With most asymptomatic CMs, particularly when the diagnosis is relatively clear by MRI characteristics, the right approach for the patient is conservative management with close follow-up Type I and II CMs are composed of acute or subacute hemorrhage and are more likely to rebleed and may warrant closer follow-up In contrast to a bleeding episode from an AVM, a bleeding episode from a CM is rarely life threatening However, there is more controversy with symptomatic CMs which hemorrhage in deep, difficult-to-access surgical locations

Arteriovenous Malformation Current Evidence Arteriovenous malformations (AVMs) are vascular abnormalities composed of a fistulous connection of arteries and veins without a normal intervening capillary bed

In the cerebral hemispheres, they frequently occur as cone-shaped lesions with the apex of the cone reaching toward the ventricles Nearly all AVMs are thought to be congenital Supratentorial location is the most common (90%) The most common presentation of an AVM is intracerebral hemorrhage (ICH) AVMs are responsible for 30% to 50% of hemorrhagic strokes in children After ICH, seizure is the second most common presentation Other presentations of AVMs include headache and focal neurologic deficits which, including seizure, may be related to steal phenomena or other alterations in perfusion in the tissue adjacent to the AVM

Size of AVM In a series of 168 patients followed after presentation without a prior hemorrhage, the size of the AVM was not found to be predictive of future hemorrhage However, other studies have found AVMs

of small size to be at higher risk of hemorrhage

AVMs and Aneurysms Prevalence of the association of AVMs with aneurysms varies from 2.7% to 22.7% This association seems to be correlated with a higher risk of hemorrhage Brown et al studied 91 patients with unruptured AVMs and found the risk of ICH in patients with coexisting aneurysm to be 7% at 1 year compared with 3% among those with AVM alone At 5 years, the risk persisted at 7% per year, while it decreased to 1.7% per year in those with an AVM not associated with aneurysms

Diagnostic Imaging A CT scan may be used as an initial screening tool for patients presenting with neurologic sequelae related to unruptured or ruptured AVMs This study can be used quickly to determine location of the lesion, acute hemorrhage, hydrocephalus, or areas of encephalomalacia from previous surgery or rupture A nonenhanced CT may show irregular hyperdense areas frequently associated with calcifications in unruptured

AVMs or acute hemorrhage with ruptured AVMs ( Fig 122.2 ) A

contrast-enhanced CT can demonstrate the nidus, feeding vessels, or dilated draining veins

MRI is superior to CT scan in delineating details of the macro architecture of the AVM, except in the case of acute hemorrhage These