DOI:10.2214/AJR.07.2355
AJR 2007; 189:W143-W145
© American Roentgen Ray Society
Treatment of Hypertension from Renal Artery Entrapment by Percutaneous CT-Guided Botulinum Toxin Injection into Diaphragmatic Crus as Alternative to Surgery and Stenting
Aslan Bilici1,
Musturay Karcaaltincaba2,
Ahmet Turan Ilica3,
Yasar Bukte1 and
Ayhan Senol1
1 Department of Radiology, Dicle University, 21280, Diyarbakir, Turkey.
2 Department of Radiology, Hacettepe University, Ankara, Turkey.
3 Department of Radiology, Diyarbakir Military Hospital, Diyarbakir,
Turkey.
Received January 5, 2007;
accepted after revision April 7, 2007.
Address correspondence to A. Bilici
(aslan{at}dicle.edu.tr).
WEB This is a Web exclusive article.
Abstract
OBJECTIVE. Our objective was to describe the technique and outcome
of CT-guided injection of botulinum toxin into the diaphragmatic crus in a
patient with hypertension caused by left diaphragmatic crus compression of the
left renal artery.
CONCLUSION. After the procedure, the patient's hypertension
disappeared. We propose this technique, which directly targets inhibition of
overactivity of the diaphragmatic crus, for treatment of hypertension caused
by diaphragmatic compression of the renal artery as an alternative to surgery
and renal artery stenting.
Keywords: botulinum injection • compression • crus of the diaphragm • MDCT • renal artery
Introduction
Renal artery entrapment by the diaphragmatic crus was first
described by d'Abreu and Strickland
[1] who reported two cases that
were proven by surgery in 1962. Surgery and stenting have been used for
treatment of renal entrapment syndrome. But the indications for endovascular
treatment with stenting or surgical bypass need to be further defined
[2]. Botulinum toxin type A
(BTX-A) is an extremely potent neurotoxin that interacts selectively with
cholinergic neurons to inhibit the pre-synaptic release of the
neurotransmitter acetylcholine. BTX-A is currently used for cosmetic and
therapeutic goals including treatment of neuromuscular disorders such as
blepharospasm, detrusor muscle overreactivity, strabismus, and cerebral palsy
to decrease muscular tonus
[3-6].
Our purpose was to describe the technique and outcome of CT-guided BTX-A
injection into the diaphragmatic crus. To our knowledge, there has been no
data in the literature related to the treatment of hypertension caused by
compression of the diaphragmatic crus by CT-guided botulinum toxin
injection.
Description of Injection Technique and Results
A 25-year-old woman complained of headache and was found to be
hypertensive. Renal artery 64-MDCT angiography was performed to exclude renal
artery stenosis. MDCT angiography revealed compression of the left renal
artery by the diaphragmatic crus, which is known as renal artery entrapment
syndrome (Fig. 1A,
1B). The left diaphragmatic
crus appeared prominent and accessible through the percutaneous route on axial
CT images. Despite the combination of doxazosin mesylate 2 mg and amlodipine
besilate 10 mg for 3 months, the patient's blood pressure remained stable at
160/110 mm Hg. A CT-guided botulinum toxin injection procedure was planned to
reduce the compression of the renal artery by the diaphragmatic crus.
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Fig. 1A —25-year-old woman who presented with headache and hypertension.
Axial CT image shows stenotic proximal left renal artery (arrow),
which is displaced medially by diaphragmatic crura (arrowhead).
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Fig. 1B —25-year-old woman who presented with headache and hypertension.
Coronal reformatted image shows normal right renal artery origin
(arrow). Left renal artery origin is stenotic and courses inferiorly
and medially from its origin (arrowhead). Diaphragmatic crus
(star) is seen displacing and compressing left renal artery
medially.
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|
Written informed consent was obtained from the patient. The procedure was
performed on a 64-MDCT scanner (Brilliance 64, Philips Medical Systems) by an
abdominal interventional radiologist. Sedation was not needed during the
procedure. The patient's vital signs, pulse oximetry, and ECG were monitored
both during the procedure and in the outpatient surgical recovery room for 12
hours after the injection. The patient was placed in the prone position. The
area between the T12 and L3 vertebrae (section thickness, 3 mm) was scanned to
find a suitable approach for the needle. After marking the skin at an
appropriate spot near the mid-line at the level of the left renal hilum, the
area was sterilized and anesthetized with subcutaneous and deep injections of
1% lidocaine buffered with bicarbonate using a 3.5-cm 25-gauge needle. A 15-cm
21-gauge needle was then advanced partially, and a CT image was obtained to
gauge depth and angulation. Then the needle was advanced in an anteromedial
direction toward the left diaphragmatic crus attachment near the vertebral
column.
A final CT image was obtained to show the appropriate needle placement in
the center of the crus (Fig.
2A,
2B). Subsequently 150 U of
BTX-A (Botox, Allergan) was injected slowly by hand in 60 seconds through the
needle. Finally the needle was withdrawn. No complication occurred during the
procedure. Oral antihypertensive drugs were discontinued after the procedure.
The patient's blood pressure was found to be 120/80 mm Hg and did not exceed
140/90 mm Hg after 2 months of the interventional procedure. A control CT
angiography could not be performed because the patient became pregnant 2
months after the injection of botulinum toxin. The patient developed
hypertension 4 months after percutaneous Botox treatment, which was still
unresponsive to medications. We hesitated to perform the percutaneous Botox
treatment in the organogenesis period of gestation, and we postponed the
procedure until the gestational age of 20 months. We repeated percutaneous
Botox treatment after shielding the fetus under CT guidance. The patient
ceased using antihypertensive drugs after Botox injection.
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Fig. 2A —25-year-old woman who presented with headache and hypertension.
Transverse CT scan obtained with patient in prone position shows 21-gauge
needle (arrow) passing between rib and spinous process toward
diaphragmatic crura.
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Fig. 2B —25-year-old woman who presented with headache and hypertension.
Transverse CT scan obtained with patient in prone position shows 21-gauge
needle is placed at center of left diaphragmatic crus (arrow).
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Discussion
Extrinsic compression of the renal artery is an infrequent cause of
renovascular hypertension, which is known as renal artery entrapment syndrome.
It occurs due to the compression of the renal artery by the presence of fibers
from the crus of the diaphragm or from a psoas muscle and can be easily
diagnosed by helical or MDCT angiography
[2,
7]. These muscle fibers cause a
verticalization of the root of the renal artery and lead to a stenosis usually
at the origin of the artery. Subsequently, the artery follows an unusual
course at an acute angle, which gives it a sigmoid course
[2,
7,
8].
Although surgery and stenting have been used for treatment of renal
entrapment syndrome, they are associated with surgical morbidity and
stent-related complications such as stenosis and occlusion. There is no
established protocol for the treatment of renal entrapment syndrome. There are
a few patients who have undergone renal artery stenting and angioplasty. But
the results are poor because of the bending and rupture of stents. Surgical
transection of the compressing part of diaphragmatic crus is another option to
release the compression, but this is an invasive option
[2,
8].
BTX-A has been used in doses of 5-10 U for the relaxation of different
muscles in several rabbit studies
[9,
10]. The safety margin of
BTX-A was determined as 13.9 ± 1.7 U/kg in mice
[11]. Odergren et al.
[12] found that a mean dose of
152 U was safe and provided sufficient paralysis in their patients with
cervical dystonia. BTX-A has an average clinical onset of action of
approximately 12-72 hours after injection, with a peak effect at 1 week and a
plateau effect continuing for 1-2 months
[13]. We decided to use 150 U
of botulinum toxin after searching the literature and consulting physicians
who have experience with this agent. Based on prior results with Botox
injection in spastic patients
[4,
14], we anticipate repeating
the Botox injection. However this form of treatment is less invasive compared
with surgical treatment and percutaneous stent placement, which are directed
toward treating underlying disease. Moreover Botox injection can be used to
confirm the renovascular origin of hypertension in patients who will undergo
surgical treatment. The usual duration of effect on muscle differs from muscle
to muscle, but for spastic patients, repeating the injection is not
recommended at intervals shorter than 4 months.
We decided to inject botulinum toxin after carefully looking at the axial
CT images, which showed asymmetric thickening of the left crus compared with
the right crus. We anticipated that overreactivity of the left diaphragmatic
crus can be inhibited by botulinum toxin. This report shows another important
advantage of MDCT angiography: the anatomic relationship of the diaphragmatic
crus and renal artery cannot be visualized to a better extent by any other
radiologic imaging method including conventional angiography and MR
angiography. Moreover visualization of this relationship between the renal
artery and diaphragmatic crus helped to implement a new treatment approach
aimed to treat the underlying pathology of diaphragmatic crus overreactivity.
CT-guided botulinum toxin injection of the diaphragmatic crus should be
performed under continuous monitoring, and patients should be observed
overnight in the hospital until further evidence is available. Bilateral
injection of diaphragmatic crura should be avoided because of the possible
risk of respiratory collapse.
In this study, we showed that injection of botulinum toxin directly into
the diaphragmatic crus under CT guidance can provide relief of renal artery
entrapment-related hypertension and appears to be a minimally invasive
alternative to surgical treatment and stenting. Further studies are required
to evaluate the effectiveness of the proposed treatment.
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Abstract
Introduction
