Discussion:
Since the advent of antibiotics, the incidence of cerebral sinovenous
thrombosis has been remarkably decreased and it has rarely been reported
in the few last decades(3).This rare condition has been more frequently
reported in the pediatric population (3)(4), with an incidence of 0.7
per 100000 children per year (5).
A clear male predominance has been documented in most
studies(2)(4)(6)(7). We also found the same predominance in our series.
The anatomic proximity of the middle ear cavity and mastoid air cells to
the dural venous sinuses makes them vulnerable to thrombophlebitis
secondary to infection and inflammation in the middle ear and
mastoid(8). Two pathogenic mechanisms of infection spread were
suggested: the direct spread of infection by erosive osteitis and
retrograde thrombophlebitis (9)(10).Edema, increase in local vascular
pressure, and hyper-coagulability stateis caused by the inflammatory
process. Therefore it leads to venous stasis and subsequent thrombosis
(11).
Severe frontal and occipital headache, otalgia,nausea, vomiting,
diplopia, loss of visual acuity, sixth nerve palsy, hemiparesis, and
spiking fever, were the most common signs and symptoms found in cases of
lateral sinus thrombosis before the era of antibiotics(1).Nowadays, the
most commonly reported symptom was a headache. The clinical presentation
was reported by Raja.K in her series “Otogenic Lateral Sinus
Thrombosis : A Review of Fifteen Patients and Changing Trends in the
Management »was made also of otorrhea, hard of hearing, and fever(2).
This finding was reproduced in Bales’s study and Sherer’s series as
well(4)(12).
Otalgia and vomiting were the commonest presenting features (63%)
followed by fever (57%) and headache (43%) in Krishnan’s study(11).
Exophthalmos, loss of visual acuity, ophthalmoplegia, ptosis, and
palpebral edema associated with headaches and fever were the major signs
and symptoms of cavernous sinus thrombosis(13)(14)(15). Zanoletti and
al. argues that the absence of typical clinical signs of mastoiditis
does not exclude the presence of otogenic lateral sinus thromboses (16).
In our series headache was present in 50% of cases and fever in 30% of
cases.
The bacteriology of cerebral sinovenous thrombosishas changed with the
use of antibiotics. Before the age of antibiotics, B-haemolytic
streptococcus and Pneumococcus were the most cultured organisms.
Pseudomonas and proteus species used to be common too(1).
The microbiological profiles are changing. Culture from the middle ear
discharge characteristically yields mixed flora, including Pseudomonas,
Proteus, Bacteroides, Staphylococcus, Enterobacteriaceae, and other
species. It is might be frequently negative due to previous antibiotic
treatment. (2)(1).In Raja’s study, 6 (40%) patients had negative
cultures. In patients with positive cultures, Proteus mirabilis (4
cases; 44%) and Pseudomonas aeruginosa (4 cases; 44%), followed by
Enterococcus fecal (1 case; 11%) and Escherichia coli (1 case;
11%).(2). In our series, the culture was positive in 7 patients.5 one
was related to a bacterial infection and 2 were related to mycologic
infection which caused the external ear infection. Among the positive
bacterial culture, we isolated Pseudomonas aeruginosa was isolated in 2
cases, Proteus mirabilis in one case, Streptococcus in one case, and
streptococcus pneumonia in one case.
The diagnosis of cerebral thrombophlebitis is based on radiographic
imaging techniques. Contrast enhancing computed tomography of the head
and neck is performed to investigate intra cranial complications of
otitis media, especially the cerebral sinovenous thrombosis (5), (9).
Lateral Sinus thrombosis may be diagnosed by the presence of the
pathognomonic empty delta sign which consists of an empty triangle
appearance created by the thrombus within the sinus surrounded by
contrast-enhanced dura (9)(17)(14)(5). In our study, the lateral sinus
was the most common location in our patients. It was confined in 70% of
cases and spread to the jugular vein in 4 cases and the cavernous sinus
in only one case.
Cavernous sinus thrombosis may be initially explored with non-contrast
CT of the head which can show subtle abnormalities such as bulging of
the lateral margins of the cavernous sinus, heterogeneous filling
defect, and engorgement of the superior and/or inferior ophthalmic
veins. In addition to the above-mentioned signs, contrast-enhanced
CT/MRI, shows the presence of asymmetric filling defects, thrombosis in
the superior ophthalmic vein, other venous tributaries, dural venous
sinuses, and cerebral veins(18). In our case, a CT scan was able to
diagnose the thrombus in the cavernous sinus by showinglow-intensity
cavernous sinus, with bulging of its lateral margins, dilation of the
ophthalmic veins, and bilateral exophthalmos more marked in the left
eye.
CT scan can misdiagnose the thrombus pathology because of bone-related
artifacts(1). Therefore, M R I / M R V is more sensitive in detecting
this complication (2).
MRI/MRV is valuable to exclude other intracranial complications like
adjacent subdural empyema, cerebritis, or cerebralabscess. It can also
eliminate the risk ofradiation compared with CT scans, especially for
children(2). The MRI does not require contrast injection to showthe
thrombuswhich seems isointense on T1-weighted images and hypointense on
T2-weighted images, with increased intraluminal sign intensity onboth T1
and T2 sequences (17). The MRV remains the gold standard in diagnosing
cerebral sinovenus thrombosis because it is a non-invasivetechnique;it
offers the advantage of precising the patency of the central venous
sinuses. Besides, itenables the distinction between a slow venous flow
and an occlusive thrombus and can be performed simultaneously with
cerebral MRI(17)(11). In our study, the MRI revealed the thrombus in 3
cases where the scanner was negative.
Additional intracranial complications must be investigated in the
presence of cerebral sinus thrombosis. The high association of cerebral
sinus thrombosis with other cranial complications is well documented
(8).
In the pre-antibiotic era, concurrent complications were present in 80%
of cases. The advent of antibiotics has reduced the incidence of
complications to 20%. Concomitant intracranial and extracranial
complications included meningitis, otitis hydrocephalus, internal
jugular vein thrombosis, and intracranial abscesses(8).
Syms and al reported a series of patients who all had concurrent
intracranial complications: 4 patients had a cerebral abscess and 3
patients had hydrocephalus(19). In the series of Kaplan et al, Twelve of
the 13 patients suffered concurrent complications, including meningitis,
cerebral abscesses, epidural abscess, and progression of the thrombus to
the transverse sinus and the internal jugular vein(3).
We have objectified70% of a cranial complication associated: such as
cerebellar abscess (3 patients) and extradural empyema in two patients,
and meningitis in one patient.
Broad-spectrum intravenous antibiotics should be started at the earliest
and must be adjusted later according to bacterial cultures. Antibiotics
have led to a reduction of incidence of complications from 80% to
20%(1). The duration of the antibiotic treatment ranged from four to
eight weeks(2). In our cases, we treated first with broad-spectrum
antibiotics then adapted to the culture result.
The role of anticoagulation therapy in the treatment of LST is unclear.
The clinician should weigh the risks and benefits of anticoagulation
therapy in cases of cerebral sinovenous thrombosis. Au. JKet al reported
a trend in the use of anticoagulation therapy, but lack the statistical
difference(20). Anticoagulation has been advanced to offer the advantage
of preventing the extension of the thrombus to distal sinuses. Thus, it
might be indicated in particular cases of thrombus propagation, embolic
events, and neurological changes(1)(21).LMWH in children with CSVTis
recommended by The American Stroke Association, outside the neonatal
period, even if there is evidence of intracranial hemorrhage(5)(22).It
is preferred to other anticoagulants(17)(5), because it preventsthrombus
propagation, improves recanalization rates, and preventslong-term
neurological sequels. But, on the other hand, it can cause
thrombocytopenia, bleeding, hemorrhagic skin necrosis, and risk of
septic emboli (11).74% of patients after, showed complete recovery with
complete resolution of the symptoms and recanalization after
antibiotherapy associated with anticoagulation (23).
Anticoagulation was administrated in all of the patients, along with
antibiotics and surgical treatment, with an excellent outcome; 9
patients recovred and only one patient had sequelae.
Surgery is an essential part of the management of this entity. It
assures a better prognosis. However, controversies persist about the
most appropriate surgical management (11). A cortical mastoidectomy is
used successfully to treat noncholesteatoma ear disease. It confirms the
diagnosis of L ST and allows the drainage of the initiating infection. A
modified radical mastoidectomy is sufficient treatment for
cholesteatomatous ears presenting acutely with cerebral sinus
thrombosis(1). Nowadays, routine ligation of the internal jugular vein
is no longer performed. It is usually reserved for unresponsive cases
with persistent septicemia,lung thromboembolism, and deep neck
infection(2)(9).
In our study, we realize a mastoidectomy isolated in 4 patients (40%),
it was associated to an internal jugular vein ligation in one case, and
to an extradural empyema evacuation in 2 patients (20%). We recommended
an antro-mastoidectomy with incision of the sinus and evacuation in 2
cases (20%).