Dolichoectatic Basilar Artery: A Review of 23 Cases 1277

TOMOYUKI NISHIZAKI, M.D. , NORIHIKO TAMAKI, M.D. , NAOYA TAKEDA, M.D. ,

TAKAYUKI SHIRAKUNI, M.D. , TAKESHI KONDOH, M.D. , AND SATOSHI MATSUMOTO, M.D.

SUMMARY The dolichoectatic basilar artery was found in 23 cases during a 10-year period. The 19 malesand 4 females ranged in age from 30 to 69 years (mean: 55 years). Hypertension was noted in 17 patients. Inseventeen (74%) of the present cases this anomaly could be visualized with CT scan. Seven patients (30%)presented with pontine infarction, which was identified on CT scan in all cases. Vertebro-basilar insufficien-cy was found in four patients. One patient had transient ischemic attacks. There were facial spasms in fourpatients and impairment of the lower cranial nerves in one. One patient exhibited cerebellar hemorrhage. Intwo patients this anomaly was found incidentally. Associated intracranial aneurysms were identified inseven patients, including fusiform aneurysms in 4 and saccular aneurysms in 3. Three patients had anaccompanying hydrocephalus. The dolichoectatic basilar artery is associated with various consequencesespecially in relation to the pathogenesis of brainstem infarction. When this anomaly is diagnosed by CTfindings, even if it is clinically asymptomatic, it may be better to treat these patients with medical therapyused to prevent ischemic stroke.

Stroke Vol 17, No 6, 1986

THE BASILAR ARTERY at times is the site ofmarked elongation, widening, and tortuosity. This isusually called a dolichoectatic basilar artery or a mega-dolichobasilar anomaly. There are many reports ofcomplications due to the compression of the brainstemor cranial nerves. Information about ischemic changesin the patients with this anomaly is scarce. The objectof this paper is to study the relationship between thisanomaly and cerebral ischemia, especially brainsteminfarction, and to discuss the significance of the clini-cal entity.

Patients and MethodsTwenty-three patients with a dolichoectatic basilar

artery were seen during a 10-year period from 1976 to1985. The 19 male and 4 female patients ranged in agefrom 30 to 69 years (mean: 55 years).

The diagnosis of this anomaly was based on radio-logical findings. The dolichoectatic basilar artery ofthis series was defined as one longer that 21 mm indistance between the upper bifurcation of the basilarartery and the dorsum sellae.' Computed tomography(CT) with and without contrast material, and four ves-sel angiography were performed in all except onepatient.

ResultsA summary of the 23 patients in the present series is

shown in table 1. There was a male predominance (19patients). Hypertension was a preexisting condition inseventeen patients (74%). The dolichoectatic basilarartery could be visualized with CT scan in 17 patients(fig. 1).

The clinical features are divided into four groupsand are summarized in table 2. Among ischemic signs,7 (30%) of 23 patients presented with pontine infarc-tion, which was identified on CT scan in all cases (fig.

From the Department of Neurosurgery, Kobe University School ofMedicine.

Address correspondence to: Dr. Tomoyuki Nishizaki, Department ofNeurosurgery, Kobe University School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650, Japan.

Received November 28, 1986, revision #1 accepted May 23, 1986.

2). Vertebro-basilar insufficiency, with such symp-toms as persistent vertigo, tinnitus, and headache, wasfound in four patients (case 2, 16, 17, 23). One patienthad transient ischemic attacks with episodes of hemi-paresis on the left side lasting from 30 minutes to onehour. Four patients had a history of cerebral infarction,including multiple "lacunar" infarctions (case 13, 20)(fig. 3) and left temporal infarction in two (case 5, 10).

As evidence of cranial nerve compression, facialspasm was noted in 4 patients and impairment of theninth, tenth, and twelfth nerves in one patient.

Seven of the patients had associated intracranial an-eurysms: 4 had fusiform aneurysms, three of whomalso had multiple giant fusiform aneurysms of bothinternal carotid arteries. One had a fusiform aneurysmat the junction of internal carotid artery and posteriorcommunicating arteries. Three patients had a saccularaneurysm. Two of 3 patients with a saccular aneurysmpresented with subarachnoid hemorrhage. One had acompletely thrombosed aneurysm 2 cms in diameter,involving the left vertebral artery-basilar artery junc-tion. Another with a 10 year history of pulseless dis-ease had a 2 cm saccular aneurysm at the tip of thebasilar artery. One patient with a 4.5 cm partiallythrombosed aneurysm of the left vertebral artery-basi-lar artery junction suffered dysarthria and cerebellarincoordination due to mass effect at the cerebello-pon-tine angle (fig. 3).

One patient with a history of hypertension had asmall hemorrhage in the cerebellar vermis. There wasno lesion detected by angiography to account for thiscerebellar hemorrhage. In two patients the dolichoec-tatic basilar artery was found incidentally. Three pa-tients had an accompanying asymptomatic hydroceph-alus (fig. 3).

Nineteen patients, including two without symp-toms, had received conservative therapy. Four patientswith facial spasm were surgically treated. The follow-up period varied from 6 months to 5 years. In two (case16, 20) of 19 patients with medical therapy the symp-toms improved slightly. The others had no improve-ment, but did not deteriorate. There were four deathsin this series: two (cases 12, 14) died of rupture of theaneurysmal sac, with massive subarachnoid hemor-

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1278 STROKE VOL 17, No 6, NOVEMBER-DECEMBER 1986

TABLE 1 Summary of 23 Patients with a Dolichoectatic Basilar Artery

CaseNo.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

Sex

M

F

M

M

M

M

M

F

F

M

M

M

M

F

M

M

M

M

M

M

M

M

M

Hyper-Age tension

43 +

54

30

43 +

43 +

47 +

50

52 +

65 +

69 +

69

56 +

66 +

56 +

52

62 +

60 +

68 +

46 +

58 +

59

53 +

66 +

Visual-ized

Clinical Presentation DEBA

vertigo, rt. hemiparesis —rt. hyperreflexia,rt. Babinski sign

vertigo —

It. facial spasm —

It. facial spasm +

ataxic gait +

dysarthria. It. hemiparesis, +It. hyperreflexia, It. Babinski sign

It. facial spasm —

impairment of the IX, X, XII +cranial nerves

deep stupor, rt. hemiparesis +rt. hyperreflexia, rt. Babinski signeyes: conjugate deviation tothe left

vertigo, It. hemiparesis, +It. hyperreflexia, It. Babinski sign

It. hemiparesis, It. hypesthesia +It. hyperreflexia, It. Babinski sign,horizontal nystagmus

sudden unconsciousness +stiff neck

dysarthria, dysphagia, +It. hemiparesis, It. hyperreflexia,It. Babinski sign,eyes: conjugate deviation tothe left

sudden unconsciousness +stiff neck

It. facial spasm +

vertigo, headache, vomiting —

vertigo, tinnitus +

drowsiness, It. hemiparesis +It. hyperreflexia, It. Babinski sign

incidentally +

dysarthria, It. cerebellar sign +

incidentally —

transient ischemic attacks +

vertigo +

CT scan Findings

OtherFindings

except DEBA

It. pontine infarction

none

none

none

cerebellar hemorrhage,hydrocephalus,It. temporal infarction

rt. pontine infarction

none

none

It. pontine infarction

rt. pontine infarction,It. temporal infarction

rt. pontine infarction

subarachnoid hemorrhage.It. ponto-cerebello junctionhigh dense mass

rt. pontine infarction,multiple small cerebralinfarctions, hydrocephalus

subarachnoid hemorrhage,It. thalamic high dense mass

none

none

none

rt. pontine infarction

none

It. cerebello-pontine anglehigh dense mass,multiple small cerebralinfarctions, hydrocephalus

none

none

none

AssociatedIntracranialAneurysms

none

none

none

none

both ICA giant fusiformaneurysms

none

none

none

none

both ICA giant fusiformaneurysms

none

It. V-B junction completethrombosed aneurysm

both ICA giant fusiformaneurysms

basilar tip aneurysm

none

rt. IC-PC fusiformaneurysm

none

none

none

It. V-B junctionaneurysm

none

none

none

DEBA = dolichoectatic basilar artery; ICA = internal carotid artery; V-B = vertebral artery-basilar artery; IC-PC = internal carotidartery-posterior communicating artery.

rhage; one (case 9) expired from pneumonia; one (case13) died of heart failure five months after the ictus.

DiscussionThe dolichoectatic basilar artery is relatively rare

and generally asymptomatic. The etiology is unclear.

Occurrence in younger people has been reported2"5 andsome congenital factors may contribute to its develop-ment. However, severe arteriosclerotic changes in thebasilar artery were noticed on angiography with asso-ciated hypertension in 74% of twenty-three patients inthis series.6"8 The diagnosis of a dolichoectatic basilar

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D0L1CH0ECTATIC BASILAR ARTERYINishizaki et a! 1279

FIGURE 1. Case 17. Precontrast CT scan(above) shows a slightly high density striatedband crossing from prepontine cistern to su-prasellar cistern. Postcontrast CT scan(below) demonstrates a wide striated band ofincreased density of the basilar artery.

artery must be confirmed by angiography, but theanomaly has been identified by CT scan.7' 9~" In seven-teen (74%) of our cases this abnormality was visual-ized with CT scan.

Most reports have related symptoms and neurologicdeficits due to compression to the brainstem or cranialnerves. In our study, facial spasm occurred in fourpatients (17%), and impairment of the lower cranialnerves (ninth, tenth, and twelfth nerves) in one. Oth-er authors have reported involvement of the third,fourth, fifth, sixth, eighth, and eleventh cranialnerves.4-6-7-9-10-12-18

The relationship between intracranial ischemicchanges and this abnormality has been described occa-sionally. Pontine infarction was found in seven pa-tients (30%) in this study. One other report of brain-stem infarction with a dolichoectatic basilar artery isavailable in the English literature.19

We assume that brainstem infarction in these pa-tients relates to the distortion of the paramedianbranches of the basilar artery resulting from the elon-gation and tortuosity of the basilar artery. In additionto the displacement of these paramedian branches se-vere arteriosclerosis develops in the basilar artery and

causes reduction of the blood flow. Presumably occlu-sion of the paramedian branches occurs at the site ofthe displacement and sharp angulation where theyoriginate from the basilar artery. In this study vertebro-basilar insufficiency was found in 4 patients and onepatient had transient ischemic attacks with episodes ofleft-sided hemiparesis. Transient ischemic attacks inpatients with a dolichoectatic basilar artery may fore-warn of brainstem infarction.

Hemiparesis in patients with this abnormality hasbeen reported.6-x In the present study four patients hada history of cerebral infarction. There were multiplelacunar infarctions in two patients and left temporalinfarction in two. The lacunar infarctions have beendescribed to be most frequent in patients who have hadlong-sustained hypertension.21 Dolichoectasia in-volves the carotid system less frequently.6-7-l0- "

Seven (30%) of the 23 patients had associated intra-cranial aneurysms. Fusiform aneurysms were seen in 4patients, in three of whom they were multiple andgiant. Fusiform aneurysms have been reported morefrequently in older age groups, more often in males,and occur generally in severely atherosclerotic basilararteries.22-23 In our study the mean age was 55 years,

FIGURE 2. Case 6. Plain CT scan (left) re-veals right pontine infarction (arrow) and asmall high density mass in the right cerebello-pontine cistern. Left vertebral angiogram(right) discloses a dolichoectatic basilarartery.

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1280 STROKE VOL 17, No 6, NOVEMBER-DECEMBER 1986

males were predominant, and severe arterioscleroticchanges were seen in the basilar artery. Although sac-cular aneurysms have been reported to be uncommonby contrast with fusiform aneurysms in these pa-tients,24 three of the 8 patients had a saccular aneu-rysms. It is interesting that all of the saccular aneu-rysms were large and were either completely orpartially thrombosed.

Rupture of the dolichoectatic basilar artery is con-sidered unlikely.6-l0 In this study one patient presented

TABLE 2 Clinical Onsets in 23 Patients with a DolichoectaticBasilar Artery

Ischemic signs

pontine infarction

V-B insufficiency

transient ischemic attacks

Compressive signs

facial spasm

impairment of the lower cranial nerves

Associated signs

subarachnoid hemorrhage

cerebellar hemorrhage

C-P angle mass sign

Incidentally

¥

1

4

1

t1

1

2

with cerebellar hemorrhage. The angiographic find-ings in this patient showed no vascular malformationand were diagnosed as afflicted with a hypertensivecerebellar hemorrhage due to rupture of a microaneu-rysm or of a necrotic arteriolar wall secondary to hy-pertensive atherosclerotic degeneration.

Three patients had accompanying hydrocephalus.The mechanism of hydrocephalus in these patients ismost likely a combination of increased cerebrospinalfluid (CSF) pulse pressure and impairment of outwardCSF flow by "countercurrent pulsations" of the basilarartery. In other words, a basilar artery extending intothe floor of the third ventricle exerts a water-hammerpulse transmitted toward the foramina of Monro result-ing in an impairment of outflow from the lateralventricles.23

When a dolichoectatic basilar artery is found by CTscan, full investigation by four vessel angiography ordigital subtraction angiography may be considered inview of the association with aneurysm. It may be wiseto treat these patients with platelet antiaggregant ther-apy to prevent brainstem or cerebral infarction, even inthe absence of clinical evidence of ischemia.

References1. Greitz T, Lofstedt S: The relationship between the third ventricle

and the basilar artery. Acta Radiol 42: 85-100, 19542. Ferry PC, Kerber C, Peterson D, Gallo AA: Arteriectasis, subar-

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DOLICHOECTATIC BASILAR ARTERY/Nishizaki et al 1281

FIGURE 3. Case 20. Plain CT scan shows an oval high densitymass in the left cerebello-pontine angle (A) and multiple lacu-nar infarctions in the hemispheres (B) (arrows). Hydrocephalusis also seen. Left vertebral angiogram (C) demonstrates a giantsaccidar aneurysm at the left vertebral artery-basilar ^rteryjunction and a dolichoectatic basilar artery.

achnoid hemorrhage in a three-month old infant. Neurology24:494-500, 1974Sacks JG, Lindenburg R: Dolichoectatic intracranial arteries:Symptomatology and pathogenesis of arterial elongation and dis-tention. Johns Hopkins Med J 122: 95-106, 1969Scotti G, Melancon D, Olivier A: Hypoglossal paralysis due tocompression by a tortuous, internal carotid artery in the neck.Neuroradiology 14: 263-265, 1978Voigt K, Beck U, Reinshagen G: A complex cerebral vascular

malformation studied by angiogTaphy: Multiple aneurysms, angio-mas and arterial ectasia. Neuroradiology 5: 117-123, 1973

6. Boeri R, Passerini A: The megadolichobasilar anomaly. J NeurolSci 1: 475-484, 1964

7. Moseley IF, Holland IM: Ectasia of the basilar artery: The breadthof the clinical spectrum and the diagnotic value of computed to-mography. Neuroradiology 18: 83-91, 1979

8. Wallace S, Jaffe ME: Cerebral arterial ectasia with saccular aneu-rysms. Radiology 88: 90-93, 1967

9. Deeb ZL, Jannetta PJ, Rosenbaum AE, Kerber CW, Drayer BP:Tortuous vertebrobasilar arteries causing cranial nerve syndromes:Screening by computed tomography. J Comput Assist Tomogr 3:774-778, 1979

10. Peterson NT, Duchesneau PM, Westbrook EL, Weinstein MA:Basilar artery ectasia demonstrated by computed tomography. Ra-diology 122: 713-715, 1977

11. Scotti G, De Grandi C, Colombo A: Ectasia of the intracranialarteries diagnosed by computed tomography. Megadolichobasilarartery: CT diagnosis. Neuroradiology (5: 183-184, 1978

12. Azar-Kia B, Palacios E, Spok M: The megadolichobasilar arteryanomaly and expansion of the internal auditory meatus. Neurora-diology 11: 109-111, 1976

13. Hopkins EW, Poser CM: Posterior cerebral artery ectasia. An un-usual cause of ophthalmoplegia. Arch Neurol 29: 279-281, 1973

14. Kerber CW, Margolis MT, Newton TH: Tortuous vertebrobasilarsystem: A cause of cranial nerve signs. Neuroradiology 4: 74—77,1972

15. Kramer RA, EckmanPB: Hemifacial spasm associated with redun-dancy of the vertebral artery. Am J Roentgenol 115: 133-136,1972

16. NappiG.MogliaA, Poloni M, Arrigo A: Hemifacial spasm associ-ated with dolichomegavertebrobasilar anomaly. Eur Neurol 15:94-101, 1977

17. Scott M, Stauffer HM: A case of aneurysmal malformation of thevertebral and basilar arteries causing cranial nerve mvolvement.Am J Roentgenol 92: 836-837, 1964

18. Stehbens WE: Pathology of the cerebral blood vessels. St Louis,CV Mosby Co: p. 118, 1972

19. Shirakuni T, Tamaki N, Matsumoto S, Fujiwara M: Megadolicho-basilar anomaly associated with brainstem infarction: A case re-port. J Comput Tomogr 9: 79-81, 1985

20. Lodder J, Janevski B, van der Lugt PJM: Megadolicho vascularmalformation of the intracranial arteries. Clin Neurol Neurosurg83: 11-18, 1981

21. Fisher CM: Lacunar strokes and infarcts: A review. Neurology 32:871-876, 1982

22. Little JR, Louis PS, Weinstein M, Dohn DF: Giant fusiform aneu-rysm of the cerebral arteries. Stroke 12: 183-188, 1981

23. Nijensohn DE, Saez RJ, Reagan TJ: Clinical significance of basilarartery aneurysms. Neurology 24: 301-305, 1974

24. Bladin PF, Donnan MGF: Cerebral arterial ectasia. Clinical Radi-ology 14: 349-352, 1963

25. Breig A, Ekbom K, Greitz T, Kugelberg E: Hydrocephalus due toelongated basilar artery: A new clinicoradiological syndrome. Lan-cet I: 874-875, 1967

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T Nishizaki, N Tamaki, N Takeda, T Shirakuni, T Kondoh and S MatsumotoDolichoectatic basilar artery: a review of 23 cases.

Print ISSN: 0039-2499. Online ISSN: 1524-4628 Copyright © 1986 American Heart Association, Inc. All rights reserved.

is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231Stroke doi: 10.1161/01.STR.17.6.1277

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