Ital J Neurol Sci (1998) 19:106-108

9 Springer-Verlag 1998

G. O r l a n d i 9 P. M o r e t t i 9 C. F i o r e t t i 9 M . P u g l i o l i
P. C o l l a v o l i 9 L. M u r r i

Bilateral medial frontal infarction in a case of azygous anterior
cerebral artery stenosis

Received: 12 June 1997 / Accepted in revised form: 20 November 1997

Abstract We describe the unusual case of a 63-year-old
woman with a history of arterial hypertension who presented
a sudden weakness of the lower limbs followed by mutism,
akinesia and dyspraxia. Magnetic resonance images showed
a bilateral medial frontal infarction. Digital subtraction angiography documented a right azygous anterior cerebral
artery with severe stenosis in its sub-callosal tract; the left
anterior cerebral artery showed mild hypoplasia with only
sub-frontal and fronto-polar branches. No embolic source
was documented. Afterwards the patient presented a gradual
and partial recovery of both motor and cognitive functions.
Key words Azygous anterior cerebral artery 9 Cerebral infarction 9 Digital subtraction angiography 9 Magnetic resonance imaging

introduction
Anterior cerebral artery (ACA) territory infarctions are
uncommon. Indeed, large series of patients with ischemic
stroke evaluated by means of computed tomography (CT)
showed that the frequency of infarctions confined to the
ACA territory ranges from 1% to 4.4% [1-4]. Moreover,
angiographic studies documented isolated occlusion of the
ACA in only 1%-3.7% of patients with cerebral ischemia [46]. Usually, ipsilateral severe carotid artery stenosis with
hemodynamic or embolic pathogenesis accounts for these
infarctions [2, 7] On the contrary, ACA atherosclerotic stenosis is unusual and often occurs in the lower part of the curve
around the genu of the corpus callosum [8]. An azygous or
unpaired ACA is a common trunk that gives rise to branches
with bihemispheric distribution; it is a rare anatomical variation documented in 1.1% of human autopsies and it is often
associated with aneurysms [9].
In this report we describe an unusual case of bilateral
frontal medial infarction caused by azygous ACA stenosis.

Case report

G. Orlandi (5:~) 9R Moretti 9C. Fioretti 9L. Murri
Department of Neurosciences and Clinical Neurology
University of Pisa
Via Roma 67, 1-56100 Pisa, Italy
M. Puglioli 9R Collavoli
Unit of Neuroradiology
University of Pisa, Pisa, Italy

A 63-year-old woman with a history of arterial hypertension
and with no other vascular risk factors presented a sudden
weakness of the lower limbs, mostly affecting her left leg.
Hypertension medication consisted of captopril (50 mg
daily) and hydrochlorothiazide (25 mg daily).
Neurological examination at admission showed a fully
oriented patient with normal speech and normal cranial
nerves. No motor deficit was present in the upper limbs,
whereas mild paraparesis was observed prevalently in the
left leg. Sensory system was normal and no cerebellar
impairment was documented. Deep Tendineus Reflexes
(DTRs) were brisk with a prevalence on the lower limbs;
Babinski's sign was present bilaterally. CT examination

G. Orlandi et al.: Bilateral infarction in azygous ACA territory
dence of recent lesions. Routine blood tests and ECG were
normal. A few hours later paraparesis worsened, and the patient presented incontinence of urine and a marked reduction
of spontaneous speech with difficulty in initiation of talking;
afterwards she exhibited mutism. Moreover, the patient developed akinesia and forced grasping of both hands. Bilateral
ideomotor apraxia was also observed.

107
A wide plasmatic auto-antibody search was negative for
anti-nuclear antibodies (FAN, FANHEP 2), anti-ENA antibodies, anti-double stranded DNA antibodies (dsDNA), anticentromere antibodies (ACA), anti-smooth muscle cells antibodies (ASMA), anti-neutrophilous cytoplasm antibodies
(ANCA) and anticardiolipin antibodies (ACLA). Coagulation tests including AT-III, protein C, protein S and APC resistance were within normal ranges. Cervical arteries duplex
scanner and transcranial Doppler sonography were normal.
Transthoracic and transesophageal echocardiography showed no evidence of embolic sources.
Magnetic resonance imaging (MRI) was performed with
a 1.5 T system two days after the onset of symptoms. Sagittal
Tl-weighted images were obtained with spin echo (SE) sequences repetition time (TR), 500 ms; echo time (TE), 15
ms; 1 acquisition). Axial proton density (PD) and T2-weighted images were obtained with fast spin echo (FSE) repetition
time (time repetition TR, 5000 ms; echo time TE, 18-19 ms;
1 acquisition) and with fast inversion recovery (FIR) (time
repetition TR, 14.500 ms; echo time TE, 130 ms; echo time
TE, 12 ms; time inversion TI, 2650 ms; 1 acquisition) sequences. The examination showed an area of hyperintense
signal on PD and T2-weighted images involving the cortical
medial frontal regions bilaterally and symmetrically, and
suggesting an ischemic lesion (Fig. 1). A few days later, digital subtraction angiography (DSA) through a right femoral
artery catheter with selective injection in the right and left internal carotid artery was performed. A dolicho-megalic appearance of both common carotid arteries and a bilaterally
normal carotid bifurcation were observed. The right internal
carotid artery showed kinking with mild stenosis in its middie extracranial tract, and kinking with coiling were present
bilaterally in the internal carotid artery prepetrous tract.
Intracranial images showed the right azygous anterior cerebral artery with severe stenosis in its sub-callosal tract. This
common trunk gave rise to branches with a bihemispheric
distribution (Fig. 2). Moreover, the left anterior cerebral
artery showed mild hypoplasia and gave rise to only subfrontal and fronto-polar branches (Fig. 2).

Fig. la-c. a Hyperintense signal on PD and T2-weighted MR axial
sections involving in a bilateral and symmetrical way the cortical
medial frontal and b the pericallosal regions, c The lesion is more
evident in the FIR sequence image

Fig. 2. Left Right azygous anterior cerebral artery with severe
stenosis (arrow) in its sub-callosal tract. Right Left anterior cerebral
artery giving rise to only sub-frontal and fronto-polar branches

108
The patient was discharged after 20 days with mild improvement of both motor and cognitive functions. A control
three months later documented a further partial recovery.

Discussion
The occurrence of a bilateral medial frontal infarction documented in this patient is due to the unusual presence of
two rare conditions: an azygous A C A and isolated severe
stenosis in its c o m m o n trunk. Indeed, azygous A C A may be
associated with the presence of aneurysms [9], although no
thromboembolic mechanism involving such anatomical
variation has been identified. Gacs et al. [2] reviewed CT
exams from 413 consecutive patients with cerebral infarction and documented an A C A territory involvement in only
3% of cases. Only one of these patients presented a bilateral A C A territory infarction with bilateral A C A occlusion
seen on angiography; no clear cause for this evidence was
found. A pathogenetic mechanism identified in A C A territory infarctions is embolism in patients with increased flow
through the anterior communicating artery because of ipsilateral carotid artery occlusion [2, 7]. Other mechanisms
are spasm, embolism or propagating thrombosis associated
with an anterior communicating aneurysm. Our case
showed none of these occurrences, whereas we did document isolated atherosclerotic stenosis of the c o m m o n trunk
of A C A in which arterial hypertension was the only identified vascular risk factor. Indeed, no embolic source nor other cause of cerebral ischemia was identified.
The patient showed symptoms attributable to the lack of
blood supply in the paracentral lobule and in the supplementary motor area [10]. The paracentral lobule impairment accounts for the crural motor deficit and the incontinence of urine. Sensory symptoms were not documented in
our case. On this matter, in relation to the posterior extent
of the A C A branches and the collaterals from the posterior
cerebral artery, sensory symptoms caused by the involvement of the postcentral giry may be absent or too mild to be
evident if patients have serious cognitive deficits. The supplementary motor area plays an important role in the initiation and regulation of voluntary movement and speech;
therefore its impairment accounts for the tourism, akinesia
and dyspraxia observed in our case. Also, the forced grasping of the hands is attributable to the involvement of the
supplementary motor area [10]. The sudden occurrence of
such symptoms may suggest an unusual ischemic lesion in
both the A C A territories that may depend on the impairment of an azygous ACA.

G. Orlandi et al.: Bilateral infarction in azygous ACA territory

Sommario
Descriviamo il caso di una donna di 63 anni
affetta da ipertensione arteriosa che ha presentato un improvviso deficit di forza agli arti inferiori seguito da mutismo, acinesia e disprassia. La risonanza magnetica (RM)
cranica ha evidenziato un infarto frontale mediale bilaterale. L'angiografia digitale ha documentato un'arteria cerebrale anteriore destra di tipo azygos con stenosi serrata nel
tratto sotto-calloso; l'arteria cerebrale anteriore sinistra
presentava una lieve ipoplasia e dava origine soltanto a rami sotto-frontali e fronto-polari. Successivamente la paziente ha presentato un graduale e parziale recupero sia del deficit motorio che cognitivo.

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