CASE REPORTEben L. Rosenthal, MD, Section Editor

ARTERIOVENOUS MALFORMATION OF THE SCALP WITHCEREBRAL STEAL

Kate Kelly, HBA,1 Jonathan R. B. Trites, MD,1 S. Mark Taylor, MD,1 Martin Bullock, MD,2

Robert D. Hart, MD1

1 Division of Otolaryngology–Head and Neck Surgery, Department of Surgery, QEII Hospital, Halifax,Nova Scotia, Canada. E-mail: drrobhart@hotmail.com2 Department of Pathology, QEII Hospital, Halifax, Nova Scotia, Canada

Accepted 29 September 2008Published online 18 March 2009 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/hed.21032

Abstract: Background. Arteriovenous malformation of the

scalp resulting from blunt trauma to the head is an unusual

occurrence and is rarely associated with neurological seque-

lae. This case details an arteriovenous malformation with a cer-

ebral steal phenomenon.

Methods. A 21-year-old man presented with an enlarging,

pulsatile mass in the right facial/temporal area without known

cause. CT and angiography were consistent with a large arteri-

ovenous malformation involving the external carotid system,

causing a secondary cerebral steal that resulted in neurologi-

cal symptoms including seizure. Surgical resection of the mass

was undertaken.

Results. The patient had an uncomplicated preoperative

course with complete resolution of all neurologic symptoms.

Conclusion. Cerebral steal is an uncommon consequence

of traumatic extracranial arteriovenous malformation. The cur-

rent literature is reviewed, and the diagnostic approach as

well as therapeutic options are discussed. VVC 2009 Wiley

Periodicals, Inc. Head Neck 31: 1520–1523, 2009

Keywords: arteriovenous malformation; traumatic; masseteric

artery; cerebral artery; steal

We report the case of a 21-year-old man whopresented with an enlarging, pulsatile mass inthe right facial/temporal area.

CASE REPORT

A 21-year-old man presented to a peripheralemergency room with a pulsatile mass on theright side of his face. The patient had a knownscalp lesion caused by blunt trauma to the headsustained 3 years prior for which he did notseek further medical treatment. He only soughtmedical attention when he noticed the massincreasing in size 3 weeks prior to presentation.

The mass extended from the root of the zy-

goma down to the angle of the mandible. It was5 to 6 cm in maximal diameter, exhibited a thrillon palpation, and had an obvious bruit. Facialnerve function was intact. No cervical lymphad-

enopathy was found, and pharyngoscopy wasnormal.

Angiography (see Figure 1) and contrast-

enhanced CT scan (Figures 2A–2C) showed a

Correspondence to: R. D. Hart

VVC 2009 Wiley Periodicals, Inc.

1520 Arteriovenous Malformation HEAD & NECK—DOI 10.1002/hed November 2009

large arteriovenous malformation involving themasseteric branch of the maxillary artery,resulting in a marked enlargement of the rightexternal, internal, and anterior jugular veins.

Enlarged draining veins and veins in the rightparapharyngeal space, masticator space, and su-perficial soft tissues resulted in a marked asym-metry of the parotid and temporal region. Themasseteric artery measured over 1 cm in width,whereas the largest varix was measured to pro-ject 3 cm laterally from the angle of the mandi-ble. The anterior, middle, and posterior cerebralarteries were normal, as were the drainingveins of the brain and the Circle of Willis. Nointracranial abnormalities were identified.

Upon presentation, the patient reported nofacial weakness and was otherwise healthy.Shortly after the scans were performed, how-ever, upon standing the patient experienced abrief loss of consciousness followed by a grandmal seizure. The patient was treated with IVDilantin and admitted to ICU for observation. Itwas noted that standing or sitting from a supineposition was associated with presyncope, expres-sive aphasia, dizziness, and loss of coordinationof his lower left limb. Seizure activity ceasedand normal functioning was recovered when thepatient was supine. It was hypothesized thatthe steal phenomenon of the arteriovenous mal-formation may be producing hypoperfusion ofthe right cerebral hemisphere via the internalcarotid system. The patient was airlifted to the

tertiary care center in Halifax, Nova Scotia, forfurther investigation and surgical treatment. Atthe Halifax treatment center, it was decidedthat the arteriovenous malformation should beremoved through a transfacial approach involv-ing a superficial parotidectomy, with an attemptto preserve all branches of the facial nerve.

On surgical exploration, the lesion was foundto be 5 cm in greatest dimension. The entireexternal carotid trunk was markedly dilated,approximating 2 cm in greatest dimension. Thiswas fully mobilized and secured with vascularloops. A superficial parotidectomy was under-taken. The region was marked by a proliferationof ectatic vessels which were subsequentlyligated and divided. With these vessel ligations,the size and pulsatility of the vascular malfor-mation decreased substantially. The lesion itselfwas difficult to dissect due to marked inflamma-tion and fibrosis, and was ultimately removedcompletely, en bloc, through a combination ofblunt and sharp dissection. Histopathologicexamination (see Figure 3) revealed a parotidarteriovenous malformation with significantinterlobular fibrosis. Sections demonstratedmarkedly dilated arteries and veins. Level IIlymph nodes of the right neck showed follicularreactive hyperplasia and markedly dilated bloodand lymphatic channels.

Following the parotidectomy, the facial nervewas tested for functionality and all branchesremained stimulable. The patient had anuncomplicated preoperative course with com-plete resolution of all neurologic symptoms.

DISCUSSION

Arteriovenous malformations are uncommonerrors of vascular morphogenesis.1 Their rarityand unpredictable behavior together render sys-tematic study, assessment of prognosis, andsuccessful treatment difficult.2 Although contro-versy exists regarding the cause of these lesions,it is generally accepted that they may be eithercongenital or traumatic in origin, with congenitallesions being significantly more common.1 How-ever, owing to the difficulty in distinguishingbetween congenital and true traumatic arteriove-nous malformations, relative incidence of theseetiologies cannot be determined with certainty.3

Scalp and parotid arteriovenous malforma-tions consist of a nidus, dilated feeders, anddraining veins. They are highly vascular, char-acterized by multiple endothelial-lined channels

FIGURE 1. Angiography revealing a right arteriovenous

malformation.

Arteriovenous Malformation HEAD & NECK—DOI 10.1002/hed November 2009 1521

between the arterial and venous systems. Thedraining veins are often grossly dilated andassociated with pulsatile scalp swelling andbruit.4 Patients commonly present with com-plaints of gradually increasing scalp or parotidswelling, cosmetic disfigurement, pain, throb-bing headaches, bruits, and occasionally scalpnecrosis and bleeding. However, arteriovenousmalformations are also frequently asymptom-atic, and may only present under the effect ofstressors such as puberty, pregnancy, or trauma.Diagnosis is made by clinical findings, history,and visualization on angiography.1,4

Arteriovenous malformations cause directshunting of high-volume arterial blood throughlow-resistance arteriovenous fistulae, oftenresulting in venous hypertension, hypoperfusionof vessels and tissue downstream, and reducedcerebral perfusion, known as the steal phenom-enon. If perfusion pressure is reduced suffi-ciently, symptomatic cerebral ischemia mayresult and manifest in the development ofprogressive, but also stable and reversible, neu-rological deficits.7 Scalp arteriovenous malfor-mations have occasionally been seen to causeneurologic problems such as epileptic seizures,

FIGURE 2. CT image of the arteriovenous malformation at the level of the mandible (A), at the level of the zygoma (B), and in the

infratemporal fossa (C). [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]

1522 Arteriovenous Malformation HEAD & NECK—DOI 10.1002/hed November 2009

focal neurological deficits, or developmental defi-cits. However, such neurological consequencesare rare in association with extracranial arterio-venous malformations, and only a few suchcases have been described in the literature. Forexample, Mohanty and Rao described a patientwhose epilepsy and mental retardation wereassociated with a scalp arteriovenous malforma-tion, whereas Ohno et al reported intracranialischemia in a case of scalp arteriovenous malfor-mation due to a steal phenomenon.4–9

The 3 paired branches of the cerebral arterythat supply blood to the brain arise from the in-ternal carotid artery, and have therefore rarelybeen seen to be involved in cerebral steal eventsassociated with extracrancial arteriovenous mal-formations.1,3 Such cerebral steal phenomenaare usually directly associated with intracerebralarteriovenous malformations5; however, we ten-tatively conclude that the extensively dilatedvessels produced by the gradual enlargement ofthe arteriovenous malformation seen in thispatient resulted in significant diversion of bloodflow from the cerebral vessels, which was ulti-mately responsible for his severe neurologicalsymptoms and syncopal events. This is supportedby the fact that this patient’s neurological symp-toms completely resolved following removal ofthe arteriovenous malformation.

Treatment of scalp arteriovenous malforma-tions is difficult due to their characteristic highshunt flow, complicated vascular anatomy, and

cosmetic considerations.4 Timely treatment isparamount, however, for prevention of hemor-rhage and neurological sequelae as well ascosmetic relief of disfigurement, pulsatile head-ache, and tinnitus. Treatment options includesurgical excision, ligation of the feeding vessels,embolization, injection of sclerosant into thenidus, and electrothrombosis.1

Successful treatment of such malformationsby embolization has been reported, but has oftenbeen found to be insufficient for those with moreextensive fistulae or with other complicatingcomponents.4 Furthermore, studies suggest thatembolization may provide only temporary reliefof symptoms on the order of months rather thanyears.2 For this reason, radical surgical excisionwith ligation of proximal and distal vessels hasgenerally been the treatment of choice.1,10 Ourpatient demonstrated complete resolution ofall neurological symptoms following surgicalresection of his arteriovenous malformation, andresultant cessation of the cerebral stealphenomenon.

REFERENCES

1. Fisher-Jeffes NS, Domingo Z, Madden M, de Villiers JC.Arteriovenous malformations of the scalp. Neurosurgery1995;36:656–660.

2. Kohout MP, Hansen M, Pribaz JJ, Mulliken JB. Arterio-venous malformations of the head and neck: natural his-tory and management. Plast Reconstr Surg 1998;102:643–654.

3. Khodadad G. Arteriovenous malformations of the scalp.Ann Surg 1973;177:79–85.

4. Lanzino G, Passacantilli E, Lemole GM, McDougall C,Spetzler RF. Scalp arteriovenous malformation draininginto the superior sagittal sinus associated with an intra-cranial arteriovenous malformation: just a coincidence?Case report. Neurosurgery 2003;52:440–443.

5. Sheth RD, Bodensteiner JB. Progressive neurologicimpairment from an arteriovenous malformation vascu-lar steal. Pediatr Neurol 1995;13:352–354.

6. Baker RP, McCarter RJ, Porter DG. Improvement in cog-nitive function after right temporal arteriovenous mal-formation excision. Br J Neurosurg. 2004;18:541–544.

7. Mast H, Mohr JP, Osipov A, et al. ‘Steal’ is an unestab-lished mechanism for the clinical presentation of cere-bral arteriovenous malformations. Stroke 1995;26:1215–1220.

8. Nakagawa I, Kawaguchi S, Iida J, Hirabayashi H, SakaiT. Postoperative hyperperfusion associated with stealphenomenon caused by a small arteriovenous malforma-tion: case report. Neurologia Medico-chirurgica2005;45:363–366.

9. Moon K, Yoon S, Shim J, Yun I. Arteriovenous mal-formation of the scalp: efficacy of computed tomogra-phy angiography. J Korean Neurosurg Soc 2005;38:396–398.

10. Gurkanlar D, Gonu M, Solmaz I, Gonul E. Cirsoidaneurysms of the scalp. Neurosurg Rev 2006;29:208–212.

FIGURE 3. Parotid tissue containing abnormal small arteries,

consistent with an arteriovenous malformation (Hematoxylin-

Eosin stain, original magnification �40). [Color figure can

be viewed in the online issue, which is available at www.

interscience.wiley.com.]

Arteriovenous Malformation HEAD & NECK—DOI 10.1002/hed November 2009 1523