SHORT REPORT

Iatrogenic cortical aneurysm post-craniotomy

MARCO ANTONIO ZANINI, RODRIGO ALMEIDA BORGES, GUSTAVO HENRIQUE

NUNES AQUINO & CARLOS CLAYTON MACEDO DE FREITAS

Division of Neurosurgery, Botucatu Medical School, Sao Paulo State University (UNESP) Botucatu, SP, Brazil

AbstractTaking into account the number of craniotomies performed every day around the world, iatrogenic aneurysm post-craniotomy is extremely rare with only anecdotal cases reported in literature. We report an iatrogenic aneurysm affecting acortical vessel which probably developed during dural closure of a conventional craniotomy. The aneurysm was discovered 6months after surgery on a routine control angiography. The patient was successfully treated by trapping the parent vessel andexcising the aneurysm. Histopathological findings were compatible with a true type of traumatic aneurysm. The possibility ofthis rare condition occurring highlights the risk of arterial injury during craniotomy.

Key words: Cerebral aneurysm, iatrogenic, cortical vessel, craniotomy, postoperative complications.

Introduction

Traumatic intracranial aneurysms are rare, repre-

senting less than 1% of all aneurysms.1,2 They most

frequently occur after closed or penetrating head

injury, but may also occur after neurosurgical

procedures. Most cases result in immediate haemor-

rhage and subsequent aneurysm dilation that can

result in catastrophic rebleeding days or months

later.1 Delayed diagnosis leads to increased morbid-

ity and mortality, especially if rupture has occurred.

Iatrogenic aneurysm is a form of traumatic

aneurysm resulting from inadvertent direct injury to

the arterial wall following several neurosurgical

procedures. More often reported after trans-sphe-

noidal approach, it can also occur after ventricular

puncture, stereotactic biopsy, shunt insertion, or any

type of craniotomy.3–5 We report a case which

probably developed after peripheral vascular injury

during conventional craniotomy.

Case report

A 48-year-old woman was admitted to our depart-

ment with a spontaneous subarachnoid haemorrhage

due to a left middle cerebral artery aneurysm on the

M1 segment (Fig. 1A). The patient underwent

conventional pterional craniotomy and clipping. No

intercurrence occurred during surgery, except for

minor bleeding during dural closure; this was con-

trolled by irrigation. Post-operative CT showed no

abnormality. Postoperative evolution was uneventful.

A routine clip control angiogram performed 6 months

later showed a small aneurysm in the orbitofrontal

branch of the middle cerebral artery. This aneurysm

presented irregular contours, late filling in the arterial

phase, and slow emptying (Fig. 1B). The craniotomy

was reopened and the aneurysm was located in the

lateral part of the orbital surface of the left frontal

lobe, adhering to the inner surface of the duramater

and close to the suture line.

The parent vessel was completely involved by the

aneurysm in a globular fashion. Proximal and distal

ends of the aneurysm were trapped with clips and

excised. Histopathology showed evidence of recent

thrombus in the aneurysm lumen, absence of elastic

lamina and lymphomononuclear inflammatory reac-

tions, siderophils, and mucoid degeneration. These

findings were consistent with a true or dissecting type

aneurysm. Postoperative evolution was uneventful.

Discussion

Iatrogenic traumatic aneurysm can be histologically

classified as true, false, mixed, or dissecting.1–3,5

False aneurysms are more common and result from

the disruption of all 3 vessel wall layers and

hematoma formation, which stops the bleeding by

Correspondence: Marco Antonio Zanini, Department of Neurology, Botucatu Medical School, Sao Paulo State University (UNESP), 18618-970, Botucatu, SP,

Brazil. Tel: þ55 (14) 3814-1299. Fax: þ55 (14) 3811-5965. E-mail: mzanini@fmb.unesp

Received for publication 3 August 2009. Accepted 15 November 2009.

British Journal of Neurosurgery, April 2010; 24(2): 214–215

ISSN 0268-8697 print/ISSN 1360-046X online � The Neurosurgical Foundation

DOI: 10.3109/02688690903507505

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counterpressure. The blood causes an inflammatory

reaction in the surrounding tissues, with formation of

a fibrous capsular wall and aneurysmal dilation. True

aneurysms arise from variable disruption of the

internal elastic layer and media with an intact

adventitia forming the outer wall of the aneurysm.

Mixed aneurysm is formed after rupture of a true

aneurysm giving rise to a secondary false aneurysm.

A dissecting aneurysm can result from luminal shear

forces and secondary arterial dissection leading to

aneurysm dilation. The relative incidence of these

histological types is not known1

and all of them may

be saccular or fusiform in shape.2

In our case, traumatic origin was defined by

post-surgical development, cortical location, and

angiographic features. An inadvertent direct injury

to the cortical vessel during dural closure was

probably the cause of arterial wall fragility allowing

aneurysm dilation. However, a dissecting lesion to

the cortical vessel during spatula retraction causing

vascular injury and aneurysm could not be ruled

out.

Unlike traumatic aneurysm after head trauma, the

real incidence and natural history of traumatic

aneurysm following intracranial surgery is not well

defined in literature. Although some of these

aneurysms may gradually expand and rupture in a

few weeks or months, others may spontaneously

empty and disappear.5 Considering the risk of late

bleeding, iatrogenic post-craniotomy aneurysm

should be promptly treated. In our case, the

iatrogenic aneurysm presented a silent course and

was only discovered after a routine control angio-

graphy.

Conclusion

Taking into account the number of craniotomies

performed every day around the world, iatrogenic

post-craniotomy aneurysm is extremely rare with

only anecdotal cases reported in literature, suggest-

ing that they may be silent or under diagnosed. To

our knowledge, this is the first case describing a true

iatrogenic aneurysm in the cortical branch of the

middle cerebral artery due to arterial injury during

duramater suture. This case highlights that if any

bleeding is seen during dural closure, the dura needs

reopening to discover what precisely has occurred

and to secure hemostasis.

Declaration of interest: The authors report no

conflicts of interest. The authors alone are respon-

sible for the content and writing of the paper.

References

1 Dubey A, Sung WS, Chen YY, et al. Traumatic intracranial

aneurysm: a brief review. J Clin Neurosci 2008;15:609–12.

2 Jenkinson MD, Basu S, Broome JC, Eldridge PR, Buxton N.

Traumatic cerebral aneurysm formation following ventriculo-

peritoneal shunt insertion. Childs Nerv Syst 2006;22:193–6.

3 Dunn IA, Woodworth GF, Siddiqui AH, et al. Traumatic

pericallosal artery aneurysm: a rare complication of transcallosal

surgery. J Neurosurg (2 suppl Pediatrics) 2007;106:153–7.

4 Stoodley MA, North JB, Reilly PL, Blumbergs PC, Sandhu A,

Cohen PA. False aneurysm following intracranial surgery. Br J

Neurosurg 1994;8:599–602.

5 Tokunaga K, Kusaka N, Nakashima H, Date I, Ohmoto T. Coil

embolization of intradural pseudoaneurysms caused by arterial

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FIG. 1. Left internal carotid angiograms oblique view. (A) Admission angiogram demonstrating an aneurysm of the M1 segment of the

middle cerebral artery at the origin of an early temporal branch. No other cortical aneurysm is present. (B) Routine control angiogram 6

months after craniotomy showing an irregular filled aneurysm in the orbitofrontal branch (cortical) of the middle cerebral artery (arrow). The

M1 aneurysm was excluded from circulation.

Iatrogenic cortical aneurysm post-craniotomy 215

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