Sasikhan Geibprasert

Dural Arteriovenous Shunts: A New Classification of Craniospinal Epidural Venous Anatomical Bases and Clinical Correlations

Background and Purpose— The craniospinal epidural spaces can be categorized into 3 different compartments related to their specific drainage role of the bone and central nervous system, the ventral epidural, dorsal epidural, and lateral epidural groups. We propose this new classification system for dural arteriovenous shunts and compare demographic, angiographic, and clinical characteristics of dural arteriovenous shunts that develop in these 3 different locations. Methods— Three hundred consecutive cases (159 females, 141 males; mean age: 47 years; range, 0 to 87 years) were reviewed for patient demographics, clinical presentation, multiplicity, presence of cortical and spinal venous reflux, and outflow restrictions and classified into the 3 mentioned groups. Results— The ventral epidural group (n=150) showed a female predominance, more benign clinical presentations, lower rate of cortical and spinal venous reflux, and no cortical and spinal venous reflux without restriction of the venous outflow. The dorsal epidural group (n=67) had a lower mean age and a higher rate of multiplicity. The lateral epidural group (n=63) presented later in life with a male predominance, more aggressive clinical presentations, and cortical and spinal venous reflux without evidence of venous outflow restriction. All differences were statistically significant (P<0.001). Conclusion— Dural arteriovenous shunts predictably drain either in pial veins or craniofugally depending on the compartment involved by the dural arteriovenous shunt. Associated conditions (outflow restrictions, high-flow shunts) may change that draining pattern. The significant differences between the groups of the new classification support the hypothesis of biological and/or developmental differences in each epidural region and suggest that dural arteriovenous shunts are a heterogeneous group of diseases.

Dangerous Extracranial–Intracranial Anastomoses and Supply to the Cranial Nerves: Vessels the Neurointerventionalist Needs to Know

SUMMARY: Transarterial embolization in the external carotid artery (ECA) territory has a major role in the endovascular management of epistaxis, skull base tumors, and dural arteriovenous fistulas. Knowledge of the potential anastomotic routes, identification of the cranial nerve supply from the ECA, and the proper choice of embolic material are crucial to help the interventionalist avoid neurologic complications during the procedure. Three regions along the skull base constitute potential anastomotic routes between the extracranial and intracranial arteries: the orbital, the petrocavernous, and the upper cervical regions. Branches of the internal maxillary artery have anastomoses with the ophthalmic artery and petrocavernous internal carotid artery (ICA), whereas the branches of the ascending pharyngeal artery are connected to the petrocavernous ICA. Branches of both the ascending pharyngeal artery and the occipital artery have anastomoses with the vertebral artery. To avoid cranial nerve palsy, one must have knowledge of the supply to the lower cranial nerves: The petrous branch of the middle meningeal artery and the stylomastoid branch of the posterior auricular artery form the facial arcade as the major supply to the facial nerve, and the neuromeningeal trunk of the ascending pharyngeal artery supplies the lower cranial nerves (CN IX–XII).

Dural Arteriovenous Shunts

Background and Purpose— The craniospinal epidural spaces can be categorized into 3 different compartments related to their specific drainage role of the bone and central nervous system, the ventral epidural, dorsal epidural, and lateral epidural groups. We propose this new classification system for dural arteriovenous shunts and compare demographic, angiographic, and clinical characteristics of dural arteriovenous shunts that develop in these 3 different locations. Methods— Three hundred consecutive cases (159 females, 141 males; mean age: 47 years; range, 0 to 87 years) were reviewed for patient demographics, clinical presentation, multiplicity, presence of cortical and spinal venous reflux, and outflow restrictions and classified into the 3 mentioned groups. Results— The ventral epidural group (n=150) showed a female predominance, more benign clinical presentations, lower rate of cortical and spinal venous reflux, and no cortical and spinal venous reflux without restriction of the venous outflow. The dorsal epidural group (n=67) had a lower mean age and a higher rate of multiplicity. The lateral epidural group (n=63) presented later in life with a male predominance, more aggressive clinical presentations, and cortical and spinal venous reflux without evidence of venous outflow restriction. All differences were statistically significant (P<0.001). Conclusion— Dural arteriovenous shunts predictably drain either in pial veins or craniofugally depending on the compartment involved by the dural arteriovenous shunt. Associated conditions (outflow restrictions, high-flow shunts) may change that draining pattern. The significant differences between the groups of the new classification support the hypothesis of biological and/or developmental differences in each epidural region and suggest that dural arteriovenous shunts are a heterogeneous group of diseases.

Pathomechanisms of Symptomatic Developmental Venous Anomalies

Background and Purpose— Although it is generally accepted that developmental venous anomalies (DVAs) are benign vascular malformations, over the past years, we have seen patients with symptomatic DVAs. Therefore, we performed a retrospective study and a literature study to review how, when, and why DVAs can become clinically significant. Methods— Charts and angiographic films of 17 patients with DVAs whose 18 vascular symptoms could be attributed to a DVA were selected from a neurovascular databank of our hospital. MRI had to be available to rule out any other associated disease. In the literature, 51 cases of well-documented symptomatic DVAs were found. Pathomechanisms were divided into mechanical and flow-related causes. Results— Mechanical (obstructive or compressive) pathomechanisms accounted for 14 of 69 symptomatic patients resulting in hydrocephalus or nerve compression syndromes. Flow-related pathomechanisms (49 of 69 patients) could be subdivided into complications resulting from an increase of flow into the DVA (owing to an arteriovenous shunt using the DVA as the drainage route; n=19) or a decrease of outflow (n=26) or a remote shunt with increased venous pressure (n=4) leading to symptoms of venous congestion. In 6 cases, no specific pathomechanisms were detected. Conclusions— Although DVAs should be considered benign, under rare circumstances, they can be symptomatic. DVAs, as extreme variations of normal venous drainage, may represent a more fragile venous drainage system that can be more easily affected by in- and outflow alterations. The integrity of the DVA needs to be preserved irrespective of the treatment that should be tailored to the specific pathomechanism.

Intracranial aneurysms: from vessel wall pathology to therapeutic approach.

An aneurysm is a focal dilatation of an arterial blood vessel. Luminal forces, such as high blood flow, shear stress and turbulence, are implicated in the pathogenesis of intracranial aneurysms, and luminal characteristics, such as sac size and morphology, are usually essential to the clinical decision-making process. Despite frequent clinical emphasis on the vessel lumen, however, the pathology underlying the formation, growth and rupture of an aneurysm mainly resides in the vessel wall. Research on the morphology and histopathology of the vessel wall reveals that intracranial aneurysms do not constitute a single disease, but are a shared manifestation of a wide range of diseases, each of which has a unique natural history and optimum therapy. This Review classifies intracranial aneurysms by vessel wall pathology, and demonstrates that understanding the morphology and pathology of this structure is important in determining the therapeutic approach. The article concludes that aneurysms represent a symptom of an underlying vascular disease rather than constituting a disease on their own.

Radiologic Assessment of Brain Arteriovenous Malformations: What Clinicians Need to Know

Brain arteriovenous malformations (AVMs) are abnormal vascular connections within the brain that are presumably congenital in nature. There are several subgroups, the most common being glomerular type brain AVMs, with fistulous type AVMs being less common. A brain AVM may also be a part of more extensive disease (eg, cerebrofacial arteriovenous metameric syndrome). When intracranial pathologic vessels are encountered at cross-sectional imaging, other diagnoses must also be considered, including large developmental venous anomalies, malignant dural arteriovenous fistulas, and moyamoya disease, since these entities are known to have different natural histories and require different treatment options. Several imaging findings in brain AVMs have an impact on decision making with respect to clinical management; the most important are those known to be associated with risk of future hemorrhage, including evidence of previous hemorrhage, intranidal aneurysms, venous stenosis, deep venous drainage, and deep location of the nidus. Other imaging findings that should be included in the radiology report are secondary effects caused by brain AVMs that may lead to nonhemorrhagic neurologic deficits, such as venous congestion, gliosis, hydrocephalus, or arterial steal.

Addictive Illegal Drugs: Structural Neuroimaging

SUMMARY: Illegal addictive drugs can lead to functional or structural impairment of the central nervous system. This review provides an overview of the structural imaging findings on CT, MR imaging, and conventional angiography related to chronic and acute abuse of the most commonly abused illegal drugs, including cannabis, organic solvents, and amphetamines and opioids and their respective derivatives. Pathomechanisms include excitotoxicity, which may lead to an acute or subacute leukoencephalopathy, and vascular complications, including vasoconstriction, vasculitis, or hypertension, which may lead to intracranial hemorrhage or ischemia. Because clinical findings alone are often nonspecific, and afflicted patients are unlikely to admit to the substance abuse, the neuroradiologist may play an important role in establishing the diagnosis and, thereby, initiating treatment.

Alcohol-induced changes in the brain as assessed by MRI and CT

This review provides an overview of structural magnetic resonance imaging and computed tomography findings of direct and indirect alcohol-related toxic effects on the brain. In addition to ethanol-related changes to the brain, this article will also describe imaging findings in the acute setting of methanol and ethylene glycol poisoning. Alcohol will lead to brain atrophy, osmotic myelinolysis, Marchiafava–Bignami disease and, especially when related to malnutrition, may also cause Wernicke encephalopathy. Brain atrophy can be reversible if alcohol abuse is stopped. If not treated, Wernicke encephalopathy can lead to coma and death and an early diagnosis is important for immediate initiation of thiamine substitution. As clinical symptoms are often unspecific, the radiologist plays an important role in the detection of alcohol abuse and its related clinical conditions.

Partial “targeted” embolisation of brain arteriovenous malformations

The treatment of pial arteriovenous brain malformations is controversial. Little is yet known about their natural history, their pathomechanisms and the efficacy and risks of respective proposed treatments. It is known that only complete occlusion of the AVM can exclude future risk of haemorrhage and that the rates of curative embolisation of AVMs with an acceptable periprocedural risk are around 20 to 50%. As outlined in the present article, however, partial, targeted embolisation also plays a role. In acutely ruptured AVMs where the source of bleeding can be identified, targeted embolisation of this compartment may be able to secure the AVM prior to definitive treatment. In unruptured symptomatic AVMs targeted treatment may be employed if a defined pathomechanism can be identified that is related to the clinical symptoms and that can be cured with an acceptable risk via an endovascular approach depending on the individual AVM angioarchitecture. This review article gives examples of pathomechanisms and angioarchitectures that are amenable to this kind of treatment strategy.

Impact of individual intracranial arterial aneurysm morphology on initial obliteration and recurrence rates of endovascular treatments: a multivariate analysis

OBJECT The goal was to investigate whether morphological features of aneurysms can be identified that determine initial success and recurrence rates of coiled aneurysms of the basilar artery tip, the posterior communicating artery (PCoA), and the anterior communicating artery. METHODS The authors evaluated 202 aneurysms in connection with their pretreatment morphological features including size, neck-to-dome ratio, angulation of the aneurysm in relation to the parent artery, orientation of the aneurysm dome, and associated anatomical variations. The mean follow-up was 19 months (range 6-96 months) after endovascular coil occlusion. Using multivariate logistic regression, probabilities for initial complete occlusion and long-term stability of the treatment were calculated. RESULTS Recanalization occurred in 49 of 202 cases. Favorable factors for long-term stability included small aneurysms with small necks. However, additional factors related to local hemodynamic forces could be identified for the different aneurysm locations, which may influence initial success rates and long-term stability of aneurysm treatment with endovascular coiling. These factors were a medial dome orientation and a symmetrical disposition of both A(1) segments (for the anterior communicating artery), a posteroinferior dome orientation and a small-size PCoA (for the PCoA), and a cranial symmetrical fusion (for the basilar artery tip). CONCLUSIONS A detailed pretreatment analysis of morphological features of aneurysms may help to determine those aneurysms that are more prone to recurrence, which could add to the treatment decision and the follow-up algorithm.