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399Discussion

Valdueza et al., Neurosonology and Neuroimaging of Stroke: A Comprehensive Reference, Second Edition (ISBN 978-3-13-141872-2), copyright © 2017 Thieme Medical Publishers All rights reserved. Usage subject to terms and conditions of license.

V2-VA-L

Fig. B26.7 Extracranial duplex, longitudinal plane. Color-coded image of the dilated left V2-VA between C5 and C6 with a diameter of

10.8 mm (white dotted line).

V2-VA-R

V2-VA-L

Fig. B26.8 Extracranial duplex, longitudinal plane. Normal ﬂ ow in the distal left V2-VA between C3 and C4 (ﬂ ow velocity 49/17 cm/s).

V2-VA-R

Fig. B26.9 Extracranial duplex, longitudinal plane. Normal diameter of the right V2-VA segment (4.4 mm).

Discussion

Clinical Aspects

The case illustrates complex vertebrobasilar pathology. Our 58-year-old patient suﬀ ered from multiple episodes of cerebral ischemia in the posterior circulation, involving the cerebellum, assumed to be in the territory of the superior cerebellar artery, and the pons. The underlying cause was an isolated high-grade mid-basilar stenosis. An endovascular stent successfully treated the stenosis. After intervention, the patient sustained another episode of pontine infarction on the contralateral side most likely caused by a perforating artery occlusion. Alternatively, an artery-to-artery embolic event from the extracranial VA dissecting aneurysm was discussed but rejected because of the infarct pattern.

The largest register of prospectively collected data, from 407 patients with ischemia of the posterior circulation, is the New England Medical Center Posterior Circulation Registry (NEMC-PCR) (Caplan et al 2004). Of the 407 patients, 87 demonstrated a BA stenosis >50% or

Fig. B26.10 Extracranial duplex, longitudinal plane. Normal ﬂ ow in the right V2-VA (ﬂ ow velocity 43/13 cm/s).

occlusion, mostly of atherosclerotic origin. Isolated occlusive processes within the BA were observed in ~45% of patients and the mid-basilar segment was aﬀ ected in ~62%. Classic vascular risk factors such as hypertension or hyperlipidemia were common. Clinically, 66% of these patients suﬀ ered from posterior circulation TIAs. More than one-half of these subsequently evolved to completed stroke with a preferential location within the pons in ~76% of cases.

Contrary to previous beliefs, the NEMC-PCR shows that the clinical outcome after brain ischemia caused by BA processes might be relatively good. This might in part be explained by the improved imaging modalities which are able to also depict less distinct ﬁ ndings. In this se- ries 72.2% of patients had a good clinical outcome. A poor clinical outcome has been associated with involvement of the distal territory, emboli, and BA occlusions as well as initially impaired consciousness (Voetsch et al 2004). In our case, it is likely that an atherosclerotic BA stenosis was present. This hypothesis is supported by the multiple known vascular risk factors, the observed atherosclerotic internal carotid artery (ICA) vessel wall changes, and the clinical presentation with recurring

400 Case 26 Extracranial Left Vertebral Artery Dissecting Aneurysm Following Basilar Artery Stenting

Fig. B26.12 (A) CTA, curviplanar reformatted image, coronal view. Widening of the left V2-VA between C5 and C6 consistent with dissecting aneurysm (arrowhead). (B) CTA, curviplanar reformatted image, lateral view: Widening of the left V2-VA between C5 and C6 consistent with dissecting aneurysm (arrowhead).

Fig. B26.11 Unenhanced cranial CT, axial plane. New right-sided hypodense area within the pons adjacent to the BA stent (arrow). Note the hyperdense structure within the BA caused by the stent itself (arrowhead).

TIAs and subsequent pontine and cerebellar infarctions (for further reading on infarct pattern and stroke etiology, see Chapter 4, “Classiﬁ cation of Arterial Stroke” un- der “Arterial Ischemia”).

The acute therapy of BA occlusive processes is discussed in Case 8. Treatment of ischemic stroke due to BA stenosis consists of several medical and interventional approaches. Finally, patients who suﬀ er from recurrent ischemia despite the use of the best medical treatment might proﬁ t from an endovascular intervention. In a small case series of 12 symptomatic patients with stent placement in the BA, no periprocedural stroke or death occurred (Gomez et al 2000). The SSYLVIA study reported on 61 treated patients with intracranial stenoses, 17 of them presenting with BA stenosis. Initial results were good, but after 6 months in 32% of patients a restenosis >50% was observed. No detailed information regarding results of BA stenting was given. Another study of 14 (out of 78) patients with BA stenosis treated by self-expandable wingspan stents reported a high periprocedural complication rate including three deaths, resulting in a mortality rate of 21% for BA intervention. Two of these patients died from vessel rupture, the third from extended infarctions (Fiorella et al 2007) (for further discussion on intracranial stenting and the SAMPPRIS study, see also Case 5).

Early stent occlusion, dissections at the stent border, and occlusion of perforator arteries are further potential complications associated with stent placement. The risk of perforator-related stroke is particularly high in patients who already present perforator-related infarctions before inter vention, compared to those with other types of infarct (8.2% versus 0.8%). Most infarcts, however, occur during the intervention or on the same day (Jiang et al 2006).

Stent placement and perfusion can easily be assessed by DSA and CT was also shown to be useful in the assessment of extra- and intracranial stent patency (Jang et al 2012, Lee et al 2014). Flat-panel CTA seems to yield better results in stent assessment than conventional multislice CTA (Struﬀ ert et al 2011). MRA, on the other hand, usually fails to visualize the ﬂ ow within the stent and is therefore of limited value. Ultrasound can easily be used to assess extra- and intracranial stent function and is already a standard diagnostic procedure for evaluation and follow-up of stented patients. While extracranial insonation makes it possible to visualize the stent and its position directly on B-mode sonography, TCCS assessment is limited to color mode and Doppler spectra analysis, which is, however, suﬃ cient to assess stent patency and quality of function.

In our case, two complications occurred despite the successful placement of the stent itself. The new pontine infarction, directly located near the stent, was probably caused by a delayed stent-related perforator occlusion 2 weeks after the interventional procedure. Furthermore, the large dissecting aneurysm in the proximal left V2-VA segment was also considered to be intervention-related, as the left VA was the access path for BA stenting. The location at the vessel entry into the ﬁ rst transverse foramen is a typical ﬁ nding in extracranial VA dissection (for fur- ther discussion of VA dissection, see also Case 19). It is worth noting that our patient did not report the typical neck pain. In VA dissections, however, pain may be absent in up to 12% of cases (Arnold et al 2006a).

Treatment of dissecting aneurysms is still a matter of debate. Formerly, oral anticoagulation was often initiated because of a suspected high risk of arterial embolism. Currently they are considered to be benign. In a group of

401Discussion

16 patients with 20 dissecting ICA aneurysms, treated with antiplatelet medication alone, no cerebral ischemia was noted during a mean follow-up period of 37 months (Guillon et al 1999). Similar results were found in a series of nine VA aneurysms which resolved spontaneously in 80%. No aneurysm enlarged and no patient suﬀ ered from ischemia while taking antiplatelet treatment (Touzé et al

2001). Surgical or endovascular treatment of an extracranial dissecting aneurysm is unnecessary and might lead to cerebral ischemia or vessel occlusion (Kadkhodayan et al 2005). It should therefore be restricted to patients in whom antithrombotic therapy fails or in whom an enlargement of the aneurysm becomes obvious (for further reading, see also Case 11).

Angiologic and Anatomic Aspects

Dissecting aneurysms have been reported to occur in 10–46% of patients with VA dissection and in 13–48% of patients with ICA dissection (Touzé et al 2001). The high variability reﬂ ects inconsistent deﬁ nitions used by diﬀ er- ent angiologic methods. It is also attributed to the variation of examination points in time, as an aneurysm can be missed in the acute phase of dissection—for example, during an initial vessel occlusion. With duplex ultrasound, aneurysms may easily be overlooked or even be undetectable. Bartels and Flügel (1996) found one distal V2VA aneurysm in 15 patients (7%) with angiographically

conﬁ rmed VA dissection. To optimize the diagnostic sen- sitivity of ultrasound in suspected VA dissection and dissecting aneurysm, examination should consist of imaging of the total visible extracranial artery from V0 to the V3 segment, paying special attention to the known dissection-prone vessel regions such as the entry site of the VA into the bony canal of the transverse processes. Positive ultrasound ﬁ ndings may be the presence of vessel lumen enlargement in B-mode and color mode with or without ﬂ ow signal alterations. A bidirectional Doppler ﬂ ow pattern may be seen within a nonthrombosed aneurysm, similar to that which can be seen physiologically in a large carotid bulb. If a VA dissecting aneurysm is detected, follow-up should concentrate on the further evolution and normalization of the vessel lumen.

MRA and CTA are clearly superior to duplex ultrasound techniques in the diagnosis and follow-up of dissecting aneurysms of the brain-supplying arteries. Although no systematic studies have addressed this speciﬁ c question, results from observational studies indicate that beside the DSA technique, multislice CTA is the most sensitive method, followed by contrast-enhanced (ce) MRA. Time-of-ﬂ ight (TOF)-MRA is not suﬃ cient in this respect, however, as it may even completely miss an existing aneurysm that would be detectable by ce MRA (Touzé et al

2001). CTA may identify dissecting aneurysms not diagnosed by MRI and TOF-MRA (Elijovich et al 2006) (for further discussion on ultrasound and neuroimaging of VA dissection, see also Case 19).

402

Case 27

Diﬀ use Cerebral Angiomatosis

Clinical Presentation

A 30-year-old woman was admitted to our department following a generalized epileptic seizure. After recovering, she reported a several years’ history of chronic throbbing headaches that were frequently accompanied by nausea and vomiting. More recently, she had developed left-sided hypoacusis, gradually worsening bilateral pulsatile tinnitus, impaired visual acuity, and recurrent transient left-sided hemiparesis, each of which lasted up to 3 hours. Her medical history had been unremarkable until she was 13 years old, at which stage a periorbital bruit, left-sided retinal edema, and retinal hemorrhages were incidentally discovered. Cranial CT performed at this time was reported to be normal. She remained asymptomatic until the age of 22, when a right central retinal venous thrombosis led to marked visual impairment in addition to a focal seizure with a left-sided hemisyndrome. Subsequently she developed symptomatic focal epilepsy and received carbamazepine as medication. The frequency of seizures increased after the birth of her daughter and changed to predominantly generalized epilepsy.

Physical examination on admission revealed bilateral periorbital pulsatile bruits, a reduced right-sided visual acuity, a bilateral retinal angiomatosis, a left-sided inner ear deafness, and a mild left-sided sensorimotor hemiparesis.

Initial Neuroradiologic Findings

Cerebral MRI on the day of admission did not reveal any ischemic lesions but did show multiple pathologic vessel signals with a right-sided predominance as well as right hemispheric brain atrophy. Intracranial contrastenhanced MR angiography (ce-MRA) showed multiple d i l a t e d , p a t h o l o g i c v e s s e l s w i t h r i g h t - s i d e d p r e d o m i nance (Fig. B27.1 and Fig. B27.2).

Suspected Diagnosis

Bihemispheric arteriovenous malformation (AVM).

Questions to Answer by Ultrasound Techniques

• Which were the arterial feeders and venous drainage vessels?

• Can a multimodal assessment be made of cerebral hemodynamics including the measurement of global cerebral blood ﬂ ow (gCBF), global cerebral circulation time (gCCT), and global cerebral blood volume (gCBV)?

Initial Neurosonologic Findings

Extracranial Duplex Sonography

B-mode ultrasound revealed no atherosclerotic vascular changes. Doppler spectrum analysis showed normal and symmetric ﬂ ow signals, but velocities were generally in- creased in all extracranial arteries and also in the internal jugular veins (IJVs) (Figs. B27.3–B27.8).

Transcranial Duplex Sonography

Transcranial color-coded sonography (TCCS) showed i n c r e a s e d ﬂ ow velocities (between 100 cm/s and 250 cm/s systolic ﬂ ow), low pulsatility indices (<0.6), and moder- ately turbulent ﬂ ow patterns in all basal cerebral arteries (Figs. B27.9–B27.14). In addition, ﬂ ow velocities were raised in the detectable cerebral venous vessels (not shown).

Multimodal Assessment (gCBF, gCCT, and gCBV)

The gCBF, assessed as the sum of blood volume ﬂ ow in both internal carotid arteries (ICAs) and vertebral arteries (VAs) was 2,620 mL/min, which is approximately three times higher than in healthy individuals. The gCCT was determined as the time delay between the arrival of the contrast bolus at the extracranial ICA and its exit at the extracranial IJV following intravenous injection of Levovist contrast bolus into an antecubital vein. In our patient, the gCCT was signiﬁ cantly shortened (2.9 seconds; r e f e r e n c e v a l u e 7 s e c o n d s ; Fig. B27.15). The calculated ultrasound-derived gCBV (gCBF × gCCT) was increased (126 mL; reference value 80 mL) (see also Chapter 3, “Parameters of Cerebral Hemodynamics”).

403Final Diagnosis

Conclusion

Generalized increase of blood ﬂ ow velocities and gCBF, re- duction of gCCT, and increase of ultrasound- determined gCBV suggestive of marked hyperemia, consistent with a diﬀ use AVM on both hemispheres.

Conventional Angiography

Digital subtraction angiography (DSA) was performed to further analyze AVM, feeding arteries, and draining patterns, and to evaluate endovascular therapeutic options. A diﬀ use, superﬁ cial cortical angiomatosis was seen on both sides comprising numerous arteriovenous shunts leading to early venous ﬁ lling of the markedly dilated superﬁ cial and deep cerebral veins (Fig. B27.16 and Fig. B27.17).

Clinical Course

The character of the malformation, consisting of a diffuse cortical angiomatosis without a classic AVM nidus and an additional retinal angiomatosis, did not allow any

interventional therapy. The malformation was considered to be the most likely cause of the patient’s signs of increased intracranial pressure (headaches, nausea) and epilepsy as well as of the mild left-sided hemiparesis. The hemiparesis was either a recurrent Todd paresis or a result of transient hemodynamic steal phenomena, caused by right-sided accentuation of the malformation and the subsequent right-sided frontoparietal brain atrophy.

The anticonvulsant treatment was optimized and additional symptomatic treatment with analgesics led to some reduction in headaches, nausea, and vomiting. However, the patient continued to have mild hemiparesis and epilepsy. It seems that the extent of the malformation had progressed from age 13 but remained stable over the last year of follow-up as control MRI and MRA did not suggest any remarkable changes in the angiomatosis.

Final Diagnosis

Bilateral cortical and retinal angiomatosis. A rare undeﬁ ned neurocutaneous syndrome was considered.

Fig. B27.1 MR T2-weighted image, axial plane. Numerous ﬂ ow- void signals with a right-sided predominance as a correlate of pathologic arterial and venous vessels. Note the mild right-sided frontoparietal cortical atrophy. (Reproduced from Schreiber et al. Diﬀ use cerebral angiomatosis. Neurology 2003;60:1216–1218, with permission of the American Academy of Neurology as administered by Wolters Kluwer.)

Fig. B27.2 Intracranial contrast-enhanced 3D MRA, lateral oblique maximal intensity projection (MIP). Note multiple dilated arterial and venous vessels.

404 Case 27 Diﬀ use Cerebral Angiomatosis

ICA-L

Fig. B27.3 Extracranial duplex, longitudinal plane. Increased ﬂ ow velocity (127/53 cm/s) and ﬂ ow volume (530 mL/min) in the left ICA.

V2-VA-L

ICA-R

Fig. B27.4 Extracranial duplex, longitudinal plane. Increased ﬂ ow ve- locity (125/58 cm/s) and ﬂ ow volume (780 mL/min) in the right ICA.

V2-VA-R

Fig. B27.5 Extracranial duplex, longitudinal plane. Increased ﬂ ow velocity (103/48 cm/s) and ﬂ ow volume (390 mL/min) in the left VA.

IJV-L

Fig. B27.7 Extracranial duplex, longitudinal plane. Increased ﬂ ow velocity (40/28 cm/s) and volume ﬂ ow (570 mL/min) in the left IJV.

Fig. B27.6 Extracranial duplex, longitudinal plane. Increased ﬂ ow velocity (92/43 cm/s) and ﬂ ow volume (280 mL/min) in the right VA.

IJV-R

Fig. B27.8 Extracranial duplex, longitudinal plane. Increased ﬂ ow ve- locity (59/38 cm/s) and volume ﬂ ow (1,170 mL/min) in the right IJV.

405Final Diagnosis

M1-MCA-L

Fig. B27.9 TCCS (tr anst emporal appro ach) , left -sided insonati on, midbrain plane. Increased ﬂ ow velocity in the left M1-MCA (ﬂ ow ve- locity 234/129 cm/s). Note overall vessel aliasing in the color-mode image caused by the generalized marked increased ﬂ ow velocities.

A1-ACA-L

M1-MCA-R

Fig. B27.10 TCCS (transtemporal approach), right-sided insonation, midbrain plane. Increased ﬂ ow velocity in the right M1-MCA (ﬂ ow velocity 247/176 cm/s).

A1-ACA-R

Fig. B27.11 TCCS (tran stempor al approach ), lef t-sid ed insonation, midbrain plane. Increased ﬂ ow velocity in the left A1-ACA (ﬂ ow velocity 200/124 cm/s).

P2-PCA-L

Fig. B27.13 TCCS (trans temp oral ap proa ch), left-s ided ins onati on, midbrain/thalamic plane. Increased ﬂ ow velocity in the left distal P2-PCA (ﬂ ow velocity 117/71 cm/s).

Fig. B27.12 TCCS (transtemporal approach), right-sided insonation, midbrain plane. Increased ﬂ ow velocity in the right A1-ACA (ﬂ ow velocity 109/65 cm/s).

P3-PCA-R

Fig. B27.14 TCCS (transtemporal approach), right-sided insonation, thalamic plane. Increased ﬂ ow velocity in the right P3-PCA (ﬂ ow velocity 96/61 cm/s).

406 Case 27 Diﬀ use Cerebral Angiomatosis

Fig. B27.15 Doppler spectrum analysis of echo contrast bolus arrival (3 mL intravenous bolus Levovist) in the extracranial ICA (top) and the contralateral extracranial IJV (bottom), assessed with bilaterally ﬁ xed 2-MHz probes. Note the echo contrast bolus arrival at ~3 seconds in the ICA and at ~6 seconds in the IJV (arrows) resulting in a gCCT of 3 seconds. The IJV spectrum appears arterialized. To prove venous origin a mild compression maneuver was performed at 30–32 seconds (arrowhead).

Fig. B27.16 DSA, right ICA injection, lateral view. Arterial phase shows diﬀ use parenchymal contrast blushing with early venous ﬁ lling of the vein of Labbé (arrows).

Discussion

Clinical Aspects

Here we describe a 30-year-old woman with a bilateral cortical and retinal angiomatosis comprising multiple small corticomeningeal arteriovenous shunts, draining bihemispherically through numerous dilated veins but without a typical AVM nidus. Consistent with the clinical course, the extent of the malformation assessed with diﬀ erent imaging methods appears to have progressed until age 22 but to have remained stable since then.

AVMs are a subgroup of intracranial vascular malformations characterized by a pathologic arteriovenous shunt. Blood vessels within the malformation carry a higher risk of rupture and up to one-half of

Fig. B27.17 DSA, right ICA injection, lateral view. The venous phase reveals multiple arteriovenous shunts draining into markedly dilated cerebral veins. (Reproduced from Schreiber et al. Diﬀ use cerebral angiomatosis. Neurology 2003;60:1216–1218, with p e r m i s s i o n o f t h e A m e r i c a n A c a d e m y o f N e u r o l o g y a s a d m i n i s t e r e d by Wolters Kluwer.)

a ﬀ ected patients primarily present with an intracranial hemorrhage (Al-Shahi and Warlow 2001, Fleetwood and Steinberg 2002). Other common symptoms are epileptic seizures, focal neurologic deﬁ cits, pulsatile tinnitus, and headaches, due to the eﬀ ects of the altered arterial and venous hemodynamic status. However, a considerable number of patients remain asymptomatic (for further discussion on clinical aspects of AVM, see also Case 4).

Human cerebral vascular malformations are classiﬁ ed according to their morphology, location, and hemodynamic characteristics. They are relatively rare and their prevalence is diﬃ cult to estimate, as a large number of aﬀ ected individuals remain asymptomatic. Common malformations, comprising an angiographically detectable arteriovenous shunt, are AVMs, dural arteriovenous ﬁ stulas, and carotid–cavernosus ﬁ stulas. Cerebral AVMs

Table B27.1 Characteristics of hereditary hemorrhagic telangiectasia (HHT), Sturge–Weber syndrome (SWS), Wyburn–Mason syndrome

(WMS), and angiomatosis Divry–Van Bogaert (ADB)

Involved systems Manifestation

Brain/meninges Eye Skin Other Age Symptoms

HHT Cerebral AVM in

20–30% (up t 1/3 multifocal),

ysms or cav-

aneur ernous angiomas, spinal AVM

SWS Capillary, calcify-

ing angiomas with uni- or bilateral corticoleptomeningeal/cerebellar location, brain atrophy, choroid plexus enlargement

WMS Mostly unilateral

arteriovenous shunts (thalamus/ mesencephalon), blood supply via ICA or VA, drainage via vein of Galen/basal venous sinuses

ADB Corticomeningeal

angiomatosis without calciﬁ cation

Cases of retinal

malformations

Choroid angiomata, secondary glaucoma

Retinal angioma/ aneurysm, exophthalmus, no glaucoma

Not reported Livedo reticularis Not reported Childhood or adult

Multiple telangiectasias, mostly facial

Facial cutaneous angioma

Hemi-telangiectasia, facial cutaneous angioma

Pulmonary, gastrointestinal, renal, hepatic AVM

Not reported Frequently within

Not reported Within the ﬁ rst

Frequently within the ﬁ rst 30 years of life

the ﬁ rst year of life

30 years of life

presentation

Epistaxis, hemoptysis, hematuria, gastrointestinal bleeding, headaches, epilepsy

Pyramidal signs, hemiparesis, hemiplegia, hemianopia, epilepsy, intellectual disability

Brainstem or cerebellar syndromes, pyramidal signs, cranial nerve palsy, hemianopia, epilepsy, mental disturbances, headaches

Childhood or adult presentation

407Discussion

in combination with vascular malformations of the skin or other organs are extremely rare and they are usually classiﬁ ed as neurocutaneous syndromes. In our patient, an AVM seemed unlikely, as AVMs usually do not involve other organs. Therefore, the presence of a vascular neurocutaneous syndrome was considered (Table B27.1) (Vonsattel and Hedley-White 1989).

In addition to cerebral angiomatosis, the diagnosis of autosomal dominant hereditary hemorrhagic t e l a n g i e c t a s i a ( H H T ) r e q u i r e s t h e p r e s e n c e o f t e l a n g i ectatic skin lesions, frequent episodes of epistaxis, or a ﬁ rst-degree relative also being aﬀ ected (Shovlin et al 2000). In Sturge–Weber syndrome (SWS), the combination of leptomeningeal arteriovenous shunts and retinal pathology is frequently encountered; however, patients usually present with facial cutaneous angiomas, meningeal calciﬁ cations, and enlargement of the choroid plexus. Moreover they develop learning disabilities or epileptic seizures in up to 75% of cases before the age of 1 year (Sujansky and Conradi 1995, Vonsattel and Hedley-White 1989). Reports of Wyburn–Mason syndrome (WMS) unequivocally describe telangiectatic skin lesions, and the cerebral arteriovenous shunts are mainly located centrally in the midbrain region (Ponce et al 2001, Ward and Katz 1983). Finally, in the rare Divry– Van Bogaert (ADB) angiomatosis, corticomeningeal angiomatosis occurs in combination with leukoencephalopathy and livedo reticularis but lacks the description of retinal involvement (Divry and Van Bogaert 1946).

Although our case had features of each of these rare syndromes, the presenting syndrome in its entirety did not fully resemble any of them. However, earlier reports have shown that there is considerable variation in the phenotypes of WMS and SWS and that they may even overlap (Gururaj et al 2000, Ponce et al 2001, Ward and Katz 1983). As SWS and ADB are the diagnoses that most closely match our case with respect to the location of the shunt, our patient may represent a phenotypic variant of either of these two syndromes. Alternatively, the unique characteristics of this case may suggest a new malformation entity (Schreiber et al 2003a).

Angiologic and Anatomic Aspects

AVM assessment comprises the evaluation of involved arteries and veins and the extent of blood ﬂ ow and brain perfusion alterations, which is essential for diagnosis and the basis for treatment planning. DSA, the gold standard for detailed AVM characterization, allows direct vessel visualization and shunt estimation via the assessment of regional or global arteriovenous circulation times, but not measurements of CBF or CBV. Current MRI techniques are focused on indirect analysis of AMV eﬀ ects on brain parenchyma (Essig et al 1999, Griﬃ ths et al 2000, Stapf et al 2000). New developments in MRI and CT techniques increasingly enable the analysis of not only morphologic but also functional aspects of cerebral perfusion (Aksoy

408 Case 27 Diﬀ use Cerebral Angiomatosis

and Lev 2000). Dynamic MR digital subtraction angiography (MR-DSA) has been developed and can be used for AVM assessment. However, the time resolution of

0.6 images per second is a major restriction (Ziyeh et al

2005). Recently, novel 4D MRA techniques with signiﬁ - cantly improved temporal and spatial resolution have been proposed for AVM assessment; HYPRFlow (highly constrained projection reconstruction using PC-VIPR ﬂ ow images for the constraint) combines increased coverage,

0.75-second temporal resolution, 0.68-mm isotropic spatial resolution, and quantitative measurement of ﬂ ow in 6 minutes (Chang et al 2015). Also, noncontrast dynamic 3D intracranial MR angiography using pseudo-continuous arterial spin-labeling (PCASL) and accelerated 3D radial acquisition have been evaluated for arteriovenous shunt assessment in a small case series and attributed high temporal and spatial resolution (Wu et al 2014).

Another approach uses dynamic 3D CTA. In a ﬁ rst small clinical case series, repeated 3D CTA scans were generated at intervals of 0.5 seconds. In the assessed AVMs the detailed angioarchitecture as well as feeder, nidus, and draining veins were clearly seen. In tumors, the technique improves the recognition of the main supplying arteries, which might be useful for treatment planning. A particular advantage of the technique is that any user-deﬁ ned imaging plane can be chosen and adapted to the planned operative access path (Matsumoto et al 2007). Since the introduction of 4D CTA using volume CT scanners, AVM may be assessed noninvasively (Klingebiel et al 2009) with a spatial resolution superior to dynamic MRA but yet with inferior time resolution (1 rotation/s) compared with DSA (6 images/s). Nevertheless 4D CTA provides similar information to the DSA technique including AVM size, location, feeding arteries, draining vein, and Spetzler–Martin grade classiﬁ cation (H. Wang et al 2014, Willems et al 2012).

Hemodynamic indices such as ﬂ ow velocity, pulsa- tility, and cerebrovascular reactivity (CVR) of aﬀ ect- ed arterial vessels are established ultrasound criteria,

commonly used for follow-up and treatment monitoring of cerebral AVMs (see also Case 4, Case 32, and Case 40). Ultrasound evaluation of gCBF and the application of contrast bolus-tracking techniques for circulation time assessments are new techniques that are able to give additional information on important hemodynamic parameters (see also “Cerebral Blood Flow Volume” under “Parameters of Cerebral Hemodynamics” and “Ultrasound Delay Test” under “Metabolic Coupling,” both in Chapter 3). In our patient, gCBF (2,620 mL/min) was approximately three times higher than in a group of age-matched controls (Schreiber et al 2003b). Using the echo contrast bolus-tracking technique, we found a signiﬁ cant shortened gCCT (2.9 seconds), within the range that is also seen in patients with a classic AVM (1.4–5.1 seconds; Schreiber et al 2002a). A gCBV calculation in our patient revealed an increased blood volume (126 mL) compared with healthy subjects (~80 mL) (Doepp et al 2003), which matched well with PET ﬁ nd- ings in classic AVM patients (Tyler et al 1989). The latter result, however, has to be interpreted cautiously because a proximally located arteriovenous shunt between a main-stem artery and a main draining vein would lead to a short gCCT and a possible underestimation of the real gCBV, interdicting gCBV calculations in classic AVM patients. However, our patient’s unique malformation comprises a distal and leptomeningeal shunt location. The gCCT shortening might therefore result not just from the arteriovenous shunting alone, but also from the generally increased ﬂ ow velocities in all cerebral vessels, reducing the eﬀ ective error of the approach. The calculated high gCBV argues in favor of this hypothesis, although the value is probably still an underestimation. Considering the clinical symptoms of continuing headache, nausea, and vomiting in our patient as possible signs of raised intracranial pressure, a high gCBV might be a plausible explanation, in particular as cerebral MRI excluded hydrocephalus or cerebrospinal ﬂ uid (CSF) circulation disturbances.

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