Neurological Research
A Journal of Progress in Neurosurgery, Neurology and Neurosciences

ISSN: 0161-6412 (Print) 1743-1328 (Online) Journal homepage: http://www.tandfonline.com/loi/yner20

EC-IC bypass improves chronic ischemia in a
patient with moyamoya disease secondary to
sickle cell disease:An in vivo microdialysis study
Aminadav Mendelowitsch, Laligam Sekhar, Rogerio Clemente & Ashfaq
Shuaib
To cite this article: Aminadav Mendelowitsch, Laligam Sekhar, Rogerio Clemente & Ashfaq
Shuaib (1997) EC-IC bypass improves chronic ischemia in a patient with moyamoya disease
secondary to sickle cell disease:An in vivo microdialysis study, Neurological Research, 19:1, 66-70,
DOI: 10.1080/01616412.1997.11740774
To link to this article: https://doi.org/10.1080/01616412.1997.11740774

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EC-IC bypass improves chronic ischemia

in a patient with moyamoya disease
secondary to sickle cell disease:
An in vivo microdialysis study
Aminadav Mendelowitsch, Laligam N. Sekhar, Rogerio Clemente
and Ashfaq Shuaib*
· Departments of Neurological Surgery and *Neurology, The George Washington University Medical Center, Washington,
DC, USA

Patients with sickle cell disease ·may develop intracranial vascular disease, with the occlusion or
obstruction of the large or small arteries, which may lead to the secondary development of moyamoya
disease. In this report, we describe the neurochemical changes in the brain before, during, and after an
extracranial-intracranial bypass procedure on a patient with sickle cell disease and a moyamoya disease
like pattern on angiography. We used the in vivo microdialysis technique to measure the on-line pH,
lactate and amino acid concentrations in the extracellular fluid. There were relatively high resting
glutamate levels and a lower-than-normal pH in the extracellular fluid prior to the bypass, associated with
chronic ischemia. During the bypass there was a short-lived increase in the glutamate levels. After
revascularization, there was a rapid decrease in the glutamate levels and an increase in the pH value. The
patient's preoperative neurological deficit improved post-operatively, corresponding to the biochemical
changes towards normal values. These changes after revascularization suggest that chronic biochemical
abnormalities due to brain ischemia may improve after cerebral revascularization. [Neural Res 1997; 19:
66-70]

Keywords: Moyamoya; chronic ischemia; microdialysis; glutamate; lactate; on-line pH

INTRODUCTION
Sickle cell disease (SCD) is due to the inheritance of a
gene for a structurally abnormal sub-unit ({:J2) of
hemaglobin. Patients with this gene have a molecular
substitution of valine for glutaminic acid at position
number six of the f:J chain, which leads to hypoxia and
deoxyhemaglobin S polymerization. The abnormal
intracellular HbS polymer changes the red blood cells
from biconcave disks to 'sickle shaped' cells. The
sickled cells sludge inside blood vessels, ·leading to
organ damage (due to chronic . ischemia), chronic
hemolytic anemia, acute vasa-occlusive crises, and the
resulting clinical manifestations of the disease 1 •
The most serious consequences of SCD are the
deleterious effects on the central nervous system caused
by cerebral infarction (about 80%) or intracranial
hemorrhage. The principal clinical .:Presentation in
patients with the disease is hemiparesis . Abnormalities
in both the large and small vessels and their territories
may also occur. Physicians diagnose the central nervous
system manifestations of sickle cell anemia based on the

Correspondence and reprint requests to: Laligam N. Sekhar, MD,
FACS, Department of Neurological Surgery, The George Washington
University Medical Center, 21 SO Pennsylvania Avenue NW, Suite 7420, Washington, DC 20037, USA. Accepted for publication July
1996.

66

Neurological Research, ·1997, Volume 19, February

clinical picture and either computed tomography (CT) or
magnetic resonance imaging (MRI). In addition, cerebral
angiography shows abnormalities in approximately 30%
of these patients. The angiographic appearance of SCD
is similar to that of moyamoya disease; namely,
spontaneous occlusion in the arteries of the circle of
Willis and the subsequent development of a collateral
circulation involving the lenticulostriate P-erforating
vessels, presumably due to chronic ischemia -4_ Several
· procedures can ·be performed to improve the cerebral
circulation of patients with compromised blood flow 5- 9 •
One such wocedure is an extracranial-intracranial (ECIC) bypass 0 .
In this article, we report on a young patient with sickle
cell disease who underwent an EC-IC graft bypass to
improve the blood supply to the brain. Before, during,
and after the bypass, we used microdialysis to measure
the extracellular cerebral amino acids, lactate· and online pH. This is the first report of the effects of chronic
brain ischemia on cerebral amino acid and lactate
levels, as well as the first study of the response of these
chemicals to revascularization.

PATIENTS AND METHODS
Patient history and clinical course
A 21 year old black man (KS) with sickle cell disease and
a history of stroke at age three presented with a second
© 1997 Forefront Publishi ng Group
0161-6412/97/010066-05

EC-/C bypass in moyamoya and sickle cell disease: Aminadav Mendelowitsch et al.

GLUTAMATE
,uM/L

GLUTAMATE

900

,u M/L

800

30

700

1

II

/4

25 {

60011. _ __

20 I~

'

500

15

400
300

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-,

·"'
•

\..

_,/

,....

I I

.~· \ ,.,.~~,.
,

1\

" . . ' " ,,. ~\

b

•

'

'

•

-....

10 ~;;><;;><::::::;,........

200

II

. . p' i

'00"'"' ..0
~~ ~'

,.

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I

II

I

o
I

,

•

~-----~

5

100
O~r-r-~~~~-,-,~~~~~-r-r-r~~~
40

50

60

70

80

90

40 so

100 110 120 130 140 150 160 170 180 190 200 210 220 230 240

60 10 eo

Minutes

A

9o 100 110120 13o 14o 1so 160110 1ao 190 200 210 220 230 24o

Minutes

B

Figure 1 A: Preoperative magnetic resonance angiography in patient KS showing the characteristic development of collateral circulation involving
small perforating vessels in moyamoya disease ('puff of smoke') on both sides. 8: Post-operative magnetic resonance angiography shows a patent
bypass graft (arrow) and less 'puff of smoke' on the left operated side

stroke one month prior to coming to our hospital. His
initial presentation consisted of bilateral leg and arm
weakness followed by a right hemiparesis. His sickle cell
disease had been very mild for a number of years, with
no neurological symptoms, and he was making a
gradual recovery from the second stroke at the time of
our evaluation. Preoperative MRI revealed a capsular
stroke in the left hemisphere and severe dilatation of the
lenticulostriate vessels, a pattern suggestive of mayamaya disease (Figure 7a) . Angiography confirmed that
he had bilateral internal carotid artery (ICA) occlusion in
the supraclinoid segment as well as the reconstitution of
middle cerebral artery (MCA) branches via dilated
lenticulostriate vessels. He had spontaneous collateral
circulation on the right side through the e(<ternal carotid
circulation, but very poor collateral circulation on the
left side. This may explain the occurrence of stroke
preferentially in the left hemisphere.
We decided to perform an EC-IC graft bypass to
provide additional blood supply to the brain. His right
hemiparesis was stable before we proceeded with the
operation. The procedure consisted of a left frontotemporal craiotomy with a radial artery graft from the
cervical internal carotid artery to the M2 segment of the
middle cerebral artery. Three M2 branches of the MCA
were observed at its trifurcation. The middle one was
selected to receive the radial artery graft because the
other two were dilated and thin-walled due to the
collateral channels. During temporary occlusion of the
MCA, the patient's systolic blood pressure was elevated
to 140/150 mmHg and he was placed in barbiturateinduced burst suppression for neuroprotection. The
distal anastomosis was performed first, a temporary
clip was placed on the radial artery graft, and the MCA
flow was resumed . The graft was led through a
retroauricular tunnel, and .then corrected proximally to
the cervical ICA. The duration of temporary occlusion
was 51 min for the M2 segment and 41 min for the
cervical ICA. The total period of burst suppression was

2 h. Intraoperative angiography revealed excellent graft
flow. Follow-up magnetic resonance angiography (MRA)
performed 1 .5 months later showed a patent graft (Figure
7b), with the disappearance of the moyamoya pattern on
the left side. Neurological examination revealed a
significant improvement in his right hemiparesis.

Microdialysis
The protocol of intraoperative microdialysis monitoring in cerebrovascular surgery was approved by the
George Washington University's Office of Human
Research. Prior to the operation, informed consent was
obtained for the microdialysis.
Immediately after the craniotomy, a microdialysis
probe (CMA-20, 4 mm membrane, 0.5 mm diameter,
CMA, Stockholm, Sweden; presterilized at 60°C with
ethylene dioxide) was inserted into the anterior portion
of the middle temporal gyrus. The rrobe was perfused
with sterile 0.9% saline at 4 J.LI min- until closing of the
dura mater. During surgery, the on-line pH of the
dialysate was recorded. Fractions of 40 microliters were
collected . After the operation, the in-vitro relative
recoveries of all parameters were measured at room
temperature using the same probe, flow rate and
perfusion medium used intraoperatively.

Amino acid and lactate analysis
The microdialysate was stored at -70°C until
measurements were performed. Glutamate, glycine
and GABA concentrations in the perfusate were
analyzed by high -performance liquid chromatography
(HPLC) with electrochemical detection using a modification of the method of Donzanti and Yamamoto 11 ,
which has been described in detail previousl/ 2 •13 .
Briefly, pre-column (Nopak C18; 3.9 x 150 mm, Waters,
Toronto, Canada) derivatization of amino acids with
ophthaldialdehyde (OPA)/betamercaptoethanol (BME)
Neurological Research, 1997, Volume 19, February 67

EC-/C bypass in moyamoya and sickle cell disease: Aminadav Mendelowitsch et a!.

was performed prior to electrochemical detection with a
715 Ultra Wisp Sample Processor (Waters, Toronto,
Canada). Due to the inherently unstable nature of the
amino acids, we used a fully automated system for the
derivation procedure. The Ultra Wisp dispensed the
reagent into the microdialysis perfusate and mixed it
thoroughly in a 200 pi loop. The injection was made
precisely two minutes after the reaction time. With a
baseline chromatography work station, the amino acid
concentrations can be measured accurately and stored
for analysis. The mobile phase consisted of 0.10 M
disodium hydrogen orthosphate, 0.13 M ethlenediamine tetraacidic acid-sodium salt and 20%
methanol. External standards of 0.625, 1.25, 2.5, 25,
100, 300 and 1300 pmol 10 pl- 1 were used for all
samples. Lactate was measured by an enzymatic
fluorimetric method using 15 pi of dialysate14. Baseline
lactate values were recorded 30 min after the insertion
-of the probe.

J.iM/L

::I

GLUTAMATE

700
600·
500
400
300

200

100

0~------------~----~~~~~~·
450

400

LACTATE

350

300

250

6 .80
6 .78
6.76

RESULTS
pH
The pH of the dialysate during the operation was stable
(between 6.70 and 6.75) but lower than our previous
experience6. There were no changes from the baseline
during clipping of the MCA or the !CA. In the early
reperfusion period and for 10 min after removal of the
temporary clip, the pH increased to values between 6.79
and 6.82 (Figure 2).

.
- ... ~ :::
6.74r:
·

:

:
:

6 .72
6.7o

6.68
6.66
6.64

.:
.:

6 •62 40

~ 50

.:
:

:

:

60

70

80

90

100: l_!.g

. _ M C A Clipped ____..

pH

.:

.:
.:
120

130

140

150 ° 160

~ ECA Clipped-...

170

180

•

190

Minutes
Figure 2: Time course of glutamate, lactate and on-line pH during the
EC-IC bypass procedure (MCA and ECA) clipping and in the early post
ischemic period (see text)

Lactate

The baseline lactate values were similar to weviously
described 'normal' lactate values in humans 5 • During
the temporary clipping of MCA there was a short peak of
420 pM 1-1 which lasted 10 min and then returned to
normal. Lactate levels remained stable during the
temporary clipping of the ICA and. in the early postischemic period (Figure 2).

Amino acids
The dialysate fluid collected during the first 30 min
was discarded. Over the next 60 min, monitoring of the
amino acids revealed an increase in the levels of
glutamate from 157 pM 1- 1 to 278 pM 1- 1 • Previous
work in Saskatoon (Canada) and Washington (USA) has
consistent!{' shown non ischemic levels to be in the 1020 pM 1- range (Figure 3). During the temporary
clipping of the ICA there was a 5.5 fold peak of
glutamate (851 pM 1- 1). The values returned to the
baseline within 20 min. In the early reperfusion period
(50 min) the glutamate began to fall and then remained
stable between 38-58 pM 1-1. GABA levels were
between 0.6 and 1.7 during most of the surgerx. A
two-fold increase was also seen in GABA (18 pM 1- 1) at
the time of the arterial occlusion.
68

Neurological Research, 1997, Volume 19, February

DISCUSSION
It has been shown that there is an increase in the
extracellular levels of glutamate with 'simulated ischemia' 16 and during seizures 17 . An increase in glutamate
also occurs in patients with subarachnoid hemorrhage18'19 and brain trauma 20. In our patient (KS), the
baseline glutamate levels were about 10 times higher
than previously recorded non ischemic levels 16 . It is
possible that sickle cell disease with chronic ischemia
may result in chronic neuronal hypoxia and a shift to
anerobic metabolism. The patient's relatively low pH
value supports this hypothesis21.
During the bypass procedure, the glutamate levels
increased. We have monitored several other patients
during vein and arterial bypass procedures for tumors or
giant aneurysms and have never seen such an increase
in glutamate levels (Figure 3). In this patient, there was
no change in the pH, glycine or lactate associated with
the increase in glutamate. The increase in glutamate
during the bypass may have been due to the temporary
vascular occlusion and further ischemia. However, the
patient suffered no apparent iII effects from the
temporary vascular occlusion. In addition, Shuaib et

EC-IC bypass in moyamoya and sickle cell disease: Aminadav Mendelowitsch et al.

A

B

Figure 3 A: Time course of glutamate during EC-IC bypass procedure in 5 patients. B: The glutamate values in patient KS with the sickle cel l and
moyamoya disease are much higher than those of the other 4 patients {JH, RW, HL and BE) undergoing EC-IC bypass

a/. have previously shown that the extracellular levels of
glutamate can change with minor insults if resting levels
are high 1 9 . For example, patients with subarachnoid
hemorrhage have elevated extracellular glutamate levels
post-operatively, and changes in temperature (both
hypothermia and hyperthermia) during this period can
produce si~nificant fluctuations in their dialysis glutamate levels 8 . (Three to five days after Sl,Jrgery, as the
glutamate levels return towards the baseline, such
fluctuations do not occur19 .) It is possible that the high
glutamate concentration seen before the bypass led to
the glutamate peak during the procedure via a similar
mechanism.
In patient KS, the glutamate values began to fall
rapidly and the pH value began to elevate slightly
immediately after revascularization . This suggests to us
that the increased cerebral blood flow reversed the
chronic neuronal hypoxia, causing the glutamate and
pH values to become closer to previously recorded
normal values.
Cerebral revascularization procedures carry a high
risk of ischemic complications. Currently, intraoperative
monitoring using electroencephalography (EEG) and
somatosensory evoked potentials (SSEPs) is the most
useful means of identifying and preventing complications. On-line microdialysis may prove to be an
additional means of monitoring patients at risk for
neurological complications during such complex procedures. The advantage of the microdialysis technique is
that the probe can be placed near the areas of brain
known to be at significant risk due to ischemic
complications. Although invasive, the tissue trauma is

minimal and we have not observed any adverse effects
in patients in over 26 such intraoperative microdialysis
procedures performed during the past year in our
institution.

ACKNOWLEDGEMENTS
Amal Nadel, MS and Hero Miyashita, BS performed the data analysis
and Roy Richardson, RN, MSN constructed the graphs.

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