Discussion
We report a rare case of lumbosacral plexopathy after embolization of
type 2 endoleak. Endoleak is defined as persistent flow of blood into
the aneurysm sac after device placement and indicates a failure to
completely exclude the aneurysm. There are 5 types of
endoleaks.6 Type 2 endoleak results from flow into and
out of the aneurysm sac from one or more patent branch
vessels.6 There is evidence to suggest that endoleak
may be associated with an increased risk of rupture.7The decision to intervene for our patient was due to the increasing sac
size, which was 7cm.
Onyx® 8is “a non-adhesive liquid
embolic agent comprised of ethylene vinyl alcohol copolymer dissolved in
dimethyl sulfoxide, and suspended micronized tantalum powder to provide
contrast for visualisation under fluoroscopy.” It is not the routine
choice for embolisation. The most common choice is embolisation coil.
The advantage of Onyx® is that it can follow the
course of small branches of vessels without cannulation. The
disadvantage is that it is hard to control the flow and volume needed,
and it may flow to unwanted areas. Our patient had aortic repair 7 years
ago, the forward flow via the lumbar arteries from the aorta was already
excluded. Her lumbar plexus blood supply was likely dependent on
collateral flow and the these collaterals were largely blocked off
likely due to back flow of the embolic agent.
Ischemic lumbosacral plexopathy after selective Onyx® embolization is a
rare occurrence and to our knowledge, one case report with similar
aetiology had been reported in the literature.5 In
that case, Onyx® liquid embolic agent was injected from the lumbar
arteries into the sac, and extensive nontargeted embolization within the
iliolumbar arterial plexus occurred. The patient was subsequently noted
to have significant weakness of his left lower limb along with sensory
deficits. The reported case was managed similarly with bed rest and
lumbar drainage.
Diagnosis of lumbosacral plexopathy can be challenging. Clinical history
is essential for diagnosis as physical examination cannot delineate the
cause of lumbosacral plexopathy. It often requires a combination of
clinical, radiological and electrophysiological test. Main differential
diagnosis being lumbosacral polyradiculopathy as clinically both has
lower motor neurone pattern of weakness. Frequently, the only way to
accurately differentiate them are through electrophysiological study.
For lumbosacral polyradiculopathy, as it is a preganglionic lesion,
nerve conduction study (NCS) is often normal. Electromyography (EMG) of
paraspinal muscle will be abnormal depending on the nerve root involved.
Conversely, lumbosacral plexopathy usually presents with abnormal NCS
and EMG depending on the nerves involved with a normal paraspinal EMG.
Prognosis of lumbosacral plexopathy is largely depending on the
aetiology. Traumatic and radiation etiology usually have a poor
prognosis, whereas inflammatory and diabetic etiology have a good
prognosis if treat promptly.9,10 Traumatic lumbosacral
plexopathy is usually associated with severe trauma resulting in nerve
disruption and radiation usually causes irreversible damage to the
nerve, hence resulting in a poorer prognosis.9Pathogenesis of diabetes lumbosacral plexopathy is not fully understood
yet with studies have suggested possible immune mediated inflammatory
microvasculitis.10 Inflammatory causes and diabetes
both have better prognosis as these cases are usually monophasic
illnesses, with prompt diagnosis and treatment with immunotherapy like
intravenous methylprednisolone, it may stop the inflammatory processes
and hasten recovery.9,10 Ischemic etiology seems to
have a poor prognosis with permanent neurological disability. In a case
series, 3 out of 4 cases of ischemic neuropathy of lumbosacral plexus
following aorto-iliac procedure have significant weakness and
disability3. One patient required a frame for
ambulation, the other two patients were wheelchair bound.
There is limited evidence available to guide rehabilitation of patients
with lumbosacral plexopathy. Core rehabilitation principles commonly
used in this group of patient, which including strengthening, address
muscular imbalances, maintain flexibility, and improve balance and gait.
Assistive devices and braces as indicated, for example ankle-foot
orthoses (AFOs) for foot drop. We can potentially extrapolate some
rehabilitation strategies from peripheral neuropathy considering
plexuses are part of peripheral nervous system. A 2014 systematic review
found balance exercises to have the highest effect on motor as well as
sensory symptoms in all types of peripheral
neuropathy.11 Studies focusing exclusively on
strength, or a combination of endurance and strength, appeared to have a
lower impact. Balance exercises improved both parameters of balance
control and gait. Strength and endurance training, not including any
balance indices only achieved improvements regarding muscle atrophy in
general like improvement on knee torques and walking capacity. The
underlying mechanisms for the beneficial effects of exercise on
peripheral neuropathy are not fully understood. Explanations include
positive modulation of regenerative mechanisms such as altered
expression of growth factors, induction of remyelination, and
accelerating axonal regeneration.12,13 Treadmill
exercise had demonstrated the potential to improve the regeneration of
transected nerves by altered expression of neurotrophic growth factors
such as nerve growth factor.14 There is little
evidence for the beneficial effect of nutritional supplements such as
vitamin E or high-dose vitamin B.15
Promising therapeutic effect of peripheral magnetic stimulation on
traumatic brachial plexopathy had been reported.16Patients were randomised to receive conventional physical therapy
modalities and active exercises as well as real or sham repetitive
magnetic stimulation (rMS) over superior trapezius muscle of the
affected limb daily for 10 sessions. Significant improvement was
observed for both muscle strength and shoulder pain in both clinical and
neurophysiological parameters. The mechanisms of the response to rMS are
still uncertain and potentially work at both spinal and supraspinal
levels.16 Apart from rMS, there are also few case
reports on use of robotic devices for brachial plexus injury
post-surgical repair which have shown to be effective and
safe.17,18 However to date, there is no evidence for
use of robotic device in lumbosacral plexopathy.
Other than functional deficit, neuropathic pain is another common
morbidity in patients affected by plexopathy.9Neuropathic pain management includes pharmacological and
non-pharmacological strategies.19 For pharmacology
treatment, first-line treatment including tricyclic antidepressants,
serotonin-noradrenaline reuptake inhibitors, pregabalin, and
gabapentin.20
Our patient had undergone traditional rehabilitation with both
restorative and compensatory approaches. She had strengthening exercises
for partially affected muscles, range of motion exercises to maintain
her flexibility, balance and gait training with aids. We could
potentially further enhance her recovery by trial of robotic gait
training and rTMS as both had shown promising results in rehabilitation
of peripheral nerve injury.
The main limitation for our case report is limited follow-up. We only
managed to review her twice at 3 months and 9 months post discharge. We
do not have information on her long term outcome beyond 9months.
Secondly, more precise outcome measures such as gait analysis may be
used to quantify functional recovery.