Background
Vascular malformations of the limbs can present with a variety of symptoms. Diagnostic
investigations uncover a range of anatomical complexity. Tools in the management of
these lesions include direct surgical intervention, percutaneous sclerotherapy, and
catheter-guided angiographic approaches. [[1]] Endovascular sclerotherapy is a more selective method aimed at reducing blood flow
within the vascular malformation. Identification of feeding vessels to muscles and
nerves are essential in reducing the risk of vascular compromise to these structures.
We report a patient with a large arteriovenous malformation (AVM) of the hip undergoing
selective endovascular embolosclerotherapy who developed a post-procedure sciatic
neuropathy.
Case presentation
A 47-year old with a large right lower extremity AVM, identified during evaluation
for exertional hip and thigh pain, underwent her fourth endovascular procedure. A
5 French sheath was placed in the left common femoral artery using standard Seldinger
technique. A pigtail catheter was inserted to the level of L-2 and the right common
iliac artery was selected using a guide wire. After initial arteriography ([Figure 1]), major feeding vessels for the medial branches of the vascular malformation deriving
from the anterior division of the internal iliac artery were identified and embolized
using tornado coils. Three milliliters of 100% ethanol was directed into the vascular
malformation. Completion arteriogram showed total reduction in size and flow of the
AVM by 75%. ([Figure 2])
Figure 1
Conventional arteriogram-Anteroposterior views of right hip and pelvis vasculature.
Iliac vessels prior to embolosclerotherapy and coil placement. The anterior division
of the internal iliac is engorged, feeding into the AVM. The profunda femoris artery
contributes to the AVM as well.
Figure 2
Conventional arteriogram-Anteroposterior views of right hip and pelvis vasculature.
Diminution of flow to the AVM post-procedure. Note reduction in size of anterior internal
iliac branches including inferior gluteal artery. (Abbreviations-EIA-external iliac
artery, Ant. Int. IA-anterior division of internal iliac artery, CFA-common femoral
artery, SFA-superficial femoral artery, PFA-profunda femoris artery, IGA-inferior
gluteal artery, Int. PA-internal pudendal artery, Obt. A-obturator artery.)
Immediately following the procedure, the patient had new complaints of right leg weakness.
Physical examination revealed complete inability to dorsiflex or invert the right
foot. She had 4/5 MRC scale strength of plantar flexion, foot inversion, and knee
flexion, with preservation of strength in hip girdle muscles and knee extensors. Her
deep tendon reflexes were 2/4 throughout with the exception of a 1/4 right ankle jerk.
She was anesthetic on her right lateral leg. Subsequent MRI of her lumbar spine and
CT of her abdomen and pelvis failed to disclose any acute pathological process. Six
weeks later, a nerve conduction study showed absent right superficial peroneal and
sural sensory responses, and absent peroneal (recording from the extensor digitorum
brevis) and tibial (recording from the abductor hallucis) motor responses. Needle
electromyography (EMG) demonstrated muscle membrane instability, manifested by fibrillation
potential and positive sharp waves in the right tibialis anterior, medial gastrocnemius,
and semitendinosus. No motor unit potentials (MUPs) were observed in the right tibialis
anterior. Small, polyphasic MUPs with decreased recruitment were noted in the semitendinosus
and gastocnemius. Needle EMG of the gluteus medius and lumbar paraspinal region was
normal.
At the time of electrodiagnosis, she had significant atrophy in her right calf, anterior
leg and hamstring muscles. Based on the clinical and electrodiagnostic examinations,
she was diagnosed with a severe, but incomplete lesion of the right sciatic nerve.
Magnetic resonance neurography was unavailable at our institution. Despite vigorous
physical therapy, she had not recovered strength since the initial post-endovascular
procedure examination. She had not undergone any subsequent nerve repair procedures
at the time of this writing.
Conclusion
Embolosclerotherapy is recommended in isolation or as part of a multi-staged approach
for treatment of appendicular vascular malformations. Where the vascular malformation
is deep with extensive muscle or bony involvement, embolosclerotherapy is preferred
to surgical treatments which may leave the patient with greater disability. [[2]] Ethanol or N-butyl cyanoacrylate are the sclerosing agents most often utilized.
Absolute ethanol is toxic to vascular endothelium, inducing thrombosis in affected
vessels. [[3]] Delivery of the agent to the nidus of the lesion is essential in reducing systemic
side effects, such as pulmonary hypertension. [[1]] Catheter-guided techniques are recommended for arteriovenous malformations, whereas
percutaneous sclerotherapy is sufficient for venous malformations. [[3]] Success as defined by reduction in the size of the vascular malformation and diminished
associated symptoms has been reported in up to 94.7% of sessions in percutaneous and
catheter-guided techniques followed for an average of 10.6 months. [[1]]
Ethanol sclerotherapy may damage peripheral nerves either through direct nerve toxicity
or ischemia. [[4]] Lee, et al [[5]] reported a series of eighty-seven patients who underwent a total of 399 sessions
of percutaneous ethanol sclerotherapy. Five nerve palsies were reported; three facial
and two peroneal. A mechanism of injury was not postulated.
Reports of catheter-guided endovascular treatments complicated by nerve injury are
scant. Liang, et al reported recurrent laryngeal nerve injury resulting in vocal cord
paralysis after embolization of patent ductus arteriosus in three infants. [[6]] Quinn, et al, published a small series of patients who underwent catheter-guided
cisplatin chemotherapy for pelvic cancers that developed femoral and sciatic nerve
lesions [[7]]. Stent-graft of an abdominal aortic aneurysm with embolization of iliac arteries
was complicated by lower extremity weakness and fecal incontinence in one patient
[[8]].
We contend that our patient’s nerve injury was the result of ischemia or toxicity
to the sciatic nerve. The acuity and severity of the lesion are consistent with either
of these pathophysiologies. The sciatic nerve is supplied by vessels ultimately derived
from the internal iliac artery. The inferior gluteal artery arises from the anterior
division of the internal iliac, descending in the pelvis to give off the sciatic artery.
This small vessel maintains the sciatic nerve blood supply through a network of vaso nervorum. Collateral vessels from the iliolumbar, lateral sacral, obturator, and internal
pudendal arteries contribute to the vascular supply of the region as well. [[7]] Ischemia resulting in nerve injury would involve the inferior gluteal artery primarily,
with secondary compromise of other anastamotic vessels.
Our patient had distal coil placement and a neurotoxic vascular sclerosing agent infused
into her right anterior internal iliac artery, causing ischemia to the affected vascular
territory, including the sciatic nerve. Her three prior infusions and coil placements
may have prevented collateral blood flow. Although limb vasculature malformations
can cause local muscle necrosis, [[9]] we found nerve conduction and electromyographic abnormalities in a sciatic nerve
distribution far distal to her lesion. The acute onset of her weakness renders a pre-existing
sciatic neuropathy unlikely.
Embolosclerotherapy for limb vascular malformations remains a valuable treatment for
a difficult condition. Awareness of the relationship of the vascular malformation
and its blood supply to nervous structures may prevent similar neurologic complications
of this procedure in the future.
Abbreviations
MRI:
magnetic resonance imaging
AVM:
arteriovenous malformation
MRC:
medical research councila
Financial disclosures
None
Competing interests
The author(s) declare that they have no competing interests.
Authors’ contributions
JN performed the literature search, wrote the manuscript, prepared the images, and
submitted the paper. WS acquired the clinical data, edited the manuscript, and edited
the paper. ML identified the case, acquired the data, and edited the paper.
Disclaimer
The opinions or assertions contained herein are the private views of the authors and
are not to be construed as official or as reflecting the views of the Department of
the Army or the Department of Defense.
