Seyyed Mostafa Ahmadi1, Keyvan Tayebi
Meibodi1, Neda Raeesi2, Mohammad
Ali Bitaraf1, Arad Iranmehr3
1: Department of Neurosurgery, Tehran University of Medical Sciences,
Imam Khomeini Hospital, Tehran, Iran
2: Research Centre, Tehran University of Medical Sciences, Tehran, Iran
3: Department of Neurosurgery, Tehran University of Medical Sciences,
Sina Hospital, Tehran, Iran
Corresponding author: Arad Iranmehr
Address: Sina Hospital, Tehran, Iran
Email:
arad.iranmehr@gmail.com
Written informed consent was obtained from the patient to publish this
report in accordance with the journal’s patient consent policy
None of the authors listed on the manuscript are employed by a
government agency that has a primary function other than research and/or
education.
Key words: Echinococcus granulosus, Hydatid cyst, Spinal
hydatidosisAbstract
In this paper, we report a rare case of asymptomatic multiple
intradural, extramedullary spinal hydatidosis; accidentally diagnosed in
a patient with signs and symptoms of a true protruded disc. Although
quite rare, vertebral hydatidosis should always be considered as a
differential diagnosis for spinal presentations, particularly in endemic
areas for echinococcosis.
Key words: Echinococcus granulosus, Hydatid cyst, Spinal
hydatidosisIntroduction
Being a Greek term, hydatid means “watery cyst”. Hydatid disease is a
zoonotic infection mainly caused by the larva form of Echinococcus
granulosus ; a helminth of the Cestoda class123.
Echinococcosis is one of the 20 Neglected Tropical Diseases (NTDs)
listed by the World Health Organization (WHO) and affects more than one
million people worldwide imposing over three billion dollars on
healthcare systems each year4. Echinococcus
granulosus mainly affects the liver and lungs. Skeletal involvement is
quite rare and occurs in only 0.2 to 1 % of all patients, while 50% of
these cases are spinal hydatidosis4. In this paper, we
aim to present a rare case of incidentally diagnosed multiple spinal
hydatidoses and give a review of the literature about the disease.
A 26-year-old male presented with low back pain that radiated to the
lower limbs accompanied by bilateral anterior thigh hypoesthesia. The
symptoms developed gradually one year ago and did not improve with
medical treatments. Three years ago, he had cardiac surgery due to
cardiac hydatidosis. He took albendazole for about one year and a half
afterwards. He had no history of contact with dogs and livestock and no
complaint of coughs, weight loss, night sweats, or other constitutional
symptoms.
At examination, the force of the proximal lower limbs was 4/5 and the
distal force was 5/5. Deep tendon, bulbocavernosus, and superficial anal
reflexes were all intact. There was no sphincter dysfunction or
hyperesthesia in the perineal area. He had hypoesthesia at L1/L2
dermatomes bilaterally. All other examinations The biochemical and
hematological profiles were within normal limits and ESR and CRP levels
were not elevated. Abdominopelvic ultrasonography and computed
tomography (CT) scans of the chest and abdomen revealed no significant
findings. In the next step, lumbosacral magnetic resonance imaging (MRI)
was performed. As was predictable from the patient’s symptoms, there was
an extruded disc at the T12/L1 level (Figure 1A). Surprisingly, we found
three well-demarcated cystic lesions with different diameters at the
level of the T12 vertebral body. Two other lesions with the same
characteristics were present at the level of the L4/L5 vertebral bodies
(Figure 1B). The lesions exhibited iso-signal intensity on T1-weighed
and hyper-signal intensity on T2-weighed images. The cystic lesions were
all intradural and possibly extramedullary at both levels. There were no
signs of cord compression or bone destruction. MRI with intravenous
contrast showed no enhancement.
With the pre-operation diagnosis of an extruded T12/L1 disc and multiple
spinal hydatid cysts, the patient underwent surgery in two stages.
During surgery, the L4/L5 laminectomy was performed, the dura was opened
and two white pearl-like cystic masses were gently removed in order to
avoid cyst rupture (Figure 2). The whole surgery field and surrounding
regions were irrigated with 3% hypertonic saline. The wound was then
stitched in layers.
At the next stage of the procedure, one week later, a T12/L1 discectomy
and Pedicular Screw Fixation (PSF) for T12 and L1 vertebrae were
performed. So, the dura was opened and three white intramedullary cysts
were excised without rupture. The site was then washed with hypertonic
saline. At that point, the wound was closed under continuous hypertonic
saline irrigation.
As a result of the operation, the patient’s neurological symptoms
improved, and he was discharged with anthelmintic treatment of
albendazole 400 mg BD for the next six months.
At the follow-up session four months later, the patient was symptom-free
and the neuraxis MRI showed no recurrence or remnant of the CNS
hydatidosis (Figure 3).
Occurring in all age groups and in both sexes, cystic echinococcosis
(CE) accounts for a substantial disease burden globally. There is an
estimated 2.2% death rate post operation and unfavorably the relapse
rate is about 6.5%45.
Cystic Echinococcosis is predominantly reported in sheep-raising areas
while being considered highly endemic in the eastern part of the
Mediterranean region, central Asia, southern and eastern Europe,
northern Africa, southern America, Siberia and western China. This
disease is not reported in Antarctica and has been eliminated through
comprehensive control programs in New Zealand, Iceland, the Falkland
Islands, Tasmania, and Cyprus64.
Human beings act as accidental intermediate hosts for Echinococcus
granulosus. Adult worms mature in the intestine of carnivorous animals
such as dogs and wolves as definitive hosts, and the eggs are shed in
their stool. Medium-sized herbivores, such as sheep and cattle ingest
the eggs. Human beings contract the disease through the direct contact
with the carnivorous animals and their feces or by ingestion of food
infected with parasite eggs. Once ingested by the human or any other
intermediate hosts, the oncosphere(true larva) hatches from the egg and
burrows into the intestinal submucosa, then migrates through veins or
lymphatic vessels to internal organs such as liver14.
The human liver acts as an effective barrier for most of the larvae.
However, some may pass through the liver and enter the right side of the
heart and then the lungs. If the larva is not lodged in the liver or
lungs, it may virtually embed anywhere in the body, such as the spleen,
peritoneum, heart, kidney, brain, spine, skeletal bones and
muscles13. Ninety percent of the larvae are eliminated
by the host reaction. However, if they survive, the metacestode or
hydatid cyst develops in the affected organ over a course of
years7.
Commonly involved organs are the liver (75%), lung (15%), brain
(2–4%), and the genitourinary tract (2–3%)8. Only
0.2 to 1% of patients experience bone involvement, and about half of
which occurs in the spine9. Echinococcus mainly
infects the thoracic spine (52%), followed by the lumbar (37%) and
then the cervical and sacral spine110.
Braithwaite and Lees had classified spinal hydatid lesions into five
groups:(a) primary intramedullary hydatid cyst, (b) intradural
extramedullary hydatid cyst, (c) extradural intraspinal hydatid cyst,
(d) hydatid disease of the vertebra, and (e) paravertebral hydatid
disease11.The first three groups are quite uncommon.
Comparing to extradural lesions, intradural hydatidosis mostly presents
as a single cyst and at a younger age125. In our young
patient, there were multiple intradural and extra-medullary spinal cysts
at two different levels. In addition, he had a history of prior cardiac
involvement.
In a systematic analysis of 467 cases of spinal hydatidosis, Neumayr et
al. reported that 78 cases (16.7%) had a history of surgical
intervention for extraspinal hydatid cysts. They proposed that it is
difficult to say whether spinal involvement in patients with a history
of extraspinal echinococcosis results from simultaneous primary
infection, or secondary hematogenous seeding or even a new exogenous
contamination5.
Hydatid cysts are mostly misdiagnosed or missed in the early stages,
since they insidiously grow for years before making any
symptoms913. The condition manifests itself as
significant cord compression and/or bone damage141.
Symptoms and signs such as radiculopathy, myelopathy, paresthesia,
paraparesis, paraplegia, sphincter malfunction and deformity are all
reported but none of them is pathognomonic of spinal
hydatosis159. Spinal hydatidosis is associated with a
high degree of morbidity and mortality10, and its
prognosis is being compared to that of malignancies (‘le cancer
blanc’) 5. Interestingly, our patient presented with
symptoms related to one extruded disc, but his spinal hydatid cysts were
asymptomatic.
There are various conditions that resemble spinal echinococcosis, which
causes challenges in preoperative diagnosis. These differential
diagnoses include spinal tuberculosis (Pott’s disease), brucellosis,
osteomyelitis, mycosis, arachnoid cyst, fibrous dysplasia, simple
solitary or aneurysmal bone cysts, spinal abscess, malignancy, and
vertebral metastases1617.
The sensitivity of serological tests to diagnose extra-hepatic
echinococcosis is low3. X-rays and CT scans are
nonspecific. In some cases, the intervertebral disc is intact, but there
are cystic lesions and irregular destruction of the vertebral
bodies179. CT scans and ultrasonography are helpful
tools for finding other lesions in the lungs, liver, and other organs.
The evaluation of other organs in our patient revealed no involvement.
When it comes to spinal hydatidosis, MRI is the best diagnostic tool for
determining the location of the cystic lesions, the spinal levels
affected, and their relationship with surrounding
organs16918. MRI images show sausage-shaped lesions
with thin walls and dome-shaped ends without septations or debris in the
lumen. A spherical lesion may occur occasionally. CSF-like signal
characteristics are found in hydatid cyst contents1.
On T1-weighted images, the parent cyst appears iso-intense or slightly
less intense than its fillings. The T2-weighted images reveal
homogeneous hyper-intense contents surrounded by a low-intense
rim1919. The low-intense rim on MRI images results
from reactive fibrosis and degeneration around the parasitic membrane
and is in accordance with the histopathological results. The existence
of a considerably hypo-intense cyst wall on T1 and T2-weighted MRI image
sequences is characteristic of spinal hydatidosis. The T2-weighted
images also may reveal the viability of the cysts where decreased high
signal and increased low signal from collapsed cyst walls indicate a
succumbed cyst19. MRI is also helpful in evaluating
the effectiveness of medical therapy and early diagnosis of
postoperative recurrence1. Histopathological reports
of the excised cyst may still confirm the diagnosis
For spinal hydatidosis, the primary treatment consists of surgical
excision followed by anthelmintic therapy to achieve neural
decompression and establish the diagnosis9. As
patients usually present at advanced stages, treatment is difficult, and
recurrence is common in most forms. The location of the cysts, the
extent of bone involvement and the presence of spinal instability
determine the type of operative procedure, the extent of resection, and
the decision whether to perform spinal stabilization or
not3 (Pamirl. 2002). Considerable care should be taken
during the surgery to avert rupture of the cysts and spillage of their
content, which can cause anaphylactic reactions and/or subsequent
recurrence9. If cysts rupture during excision, the
surgical field should be irrigated with hypertonic saline; but
unfortunately recurrence is inevitable1.
The preferred anthelmintic drug against spinal hydatidosis is
albendazole, but its efficacy and appropriate duration of treatment are
still controversial20. The world health organization
(WHO) recommends albendazole for visceral hydatid disease, with the
dosage of 10-15mg/kg/day4. Recurrence is related to
the location of the cysts and is quite uncommon in the intradural
extramedullary form of spinal hydatidosis, where there is no
intraoperative cyst rupture21.
MRI is the modality of choice in the follow-up of spinal hydatid disease
as it enables early detection of recurrences16.
Although spinal hydatid disease is a rare condition, its burden is
remarkably high. Vertebral hydatidosis should always be considered as a
differential diagnosis for typical and atypical spinal presentations,
particularly in endemic areas for echinococcosis.
Preoperative neurologic evaluation combined with MRI helps in localizing
the lesion and planning a suitable surgical approach. The treatment
consists of surgery and adjuvant anthelmintic therapy. The cysts should
be excised carefully to avoid rupture and subsequent recurrence.
Irrigation of the surgical field with hypertonic saline is also helpful.
Strict follow-up and regular MRIs are necessary to detect recurrence at
early stages. Despite medical advances, many aspects of spinal
hydatidosis are still vaguely understood. Therefore, further studies in
this field are warranted.
Disclosure of interest The authors report no conflict of interest to declare.Sources of fundingThis research did not receive any specific grant from funding agencies
in the public, commercial, or not-for-profit sectors.ConsentThe authors confirm that the patient described in this paper has given
written consent to the inclusion of material pertaining to himself, that
he acknowledges that he cannot be identified via the paper; and that the
authors have fully anonymized him.References:
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