| Cavernous sinus thrombosis | |
|---|---|
 | |
| Oblique section through the cavernous sinus. | |
| Specialty | Neurology  |
Cavernous sinus thrombosis (CST) is the formation of a blood clot within thecavernous sinus, a cavity at the base of the brain which drains deoxygenated blood from thebrain back to theheart. This is a rare disorder and can be of two types–septic cavernous thrombosis and aseptic cavernous thrombosis.[1] The most common form is septic cavernous sinus thrombosis. The cause is usually from a spreadinginfection in thenose,sinuses,ears, orteeth.Staphylococcus aureus andStreptococcus are often the associated bacteria.[citation needed]
Cavernous sinus thrombosis symptoms include: decrease or loss of vision,chemosis,exophthalmos (bulging eyes),headaches, and paralysis of thecranial nerves which course through the cavernous sinus. This infection is life-threatening and requires immediate treatment, which usually includesantibiotics and sometimes surgical drainage.[2] Aseptic cavernous sinus thrombosis is usually associated with trauma,dehydration,anemia, and other disorders.[1]
The clinical presentation of CST can be varied. Both acute, fulminant disease, and indolent, subacute presentations have been reported in the literature.The most common signs of CST are related to anatomical structures affected within the cavernous sinus, notablycranial nerves III-VI, as well as symptoms resulting fromimpaired venous drainage from theorbit and eye.[3]Classic presentations are abrupt onset of unilateral periorbitaledema,headache,photophobia, and bulging of the eye (exophthalmos).[4]
Other common signs and symptoms include:
Ptosis,chemosis,cranial nerve palsies (III, IV, V, VI).Sixth nerve palsy is the most common. Sensory deficits of the ophthalmic and maxillary branch of thefifth nerve are common. Periorbital sensory loss and impairedcorneal reflex may be noted.Papilledema,retinal hemorrhages, and decreasedvisual acuity andblindness may occur fromvenous congestion within the retina.Fever,tachycardia andsepsis may be present. Headache withnuchal rigidity (neck stiffness) may occur. One or bothpupils may be dilated and sluggishly reactive. Infection can spread to contralateralcavernous sinus within 24–48 hours of initial presentation.[4]
Septic CST most commonly results from contiguous spread of infection from a nasalfuruncle (50%),sphenoidal orethmoidal sinuses (30%) anddental infections (10%).[5] Less common primary sites of infection include tonsils, soft palate, middle ear, or orbit (orbital cellulitis). The highly anastomotic venous system of the paranasal sinuses allows retrograde spread of infection to the cavernous sinus via the superior and inferior ophthalmic veins. It was previously thought that veins in the area were valveless and that this was the major cause of the retrograde spread, but studies have since shown that the ophthalmic and facial veins are not valveless.[6]
Staphylococcus aureus is the most common infectious microbe, found in 70% of the cases.[5]Streptococcus is the second leading cause. Gram-negative rods andanaerobes may also lead to cavernous sinus thrombosis. Rarely,Aspergillus fumigatus andmucormycosis cause CST.[citation needed]
Aseptic cavernous sinus thrombosis is much less common and is usually associated with other disorders including trauma, circulatory problems,nasopharynx cancers and other tumors of the skull base, dehydration, and anemia.[7][1]
The diagnosis of cavernous sinus thrombosis is made clinically, with imaging studies to confirm the clinical impression. Proptosis, ptosis, chemosis, and cranial nerve palsy beginning in one eye and progressing to the other eye establish the diagnosis. Cavernous sinus thrombosis is a clinical diagnosis with laboratory tests and imaging studies confirming the clinical impression.[8]
CBC,ESR, blood cultures and sinus cultures help establish and identify an infectious primary source.Lumbar puncture is necessary to rule out meningitis.[citation needed]
Sinus films are helpful in the diagnosis of sphenoid sinusitis. Opacification, sclerosis, and air-fluid levels are typical findings. Contrast-enhancedCT scan may reveal underlyingsinusitis, thickening of the superior ophthalmic vein, and irregular filling defects within the cavernous sinus; however, findings may be normal early in the disease course. AnMRI using flow parameters and an MRvenogram are more sensitive than a CT scan and are the imaging studies of choice to diagnose cavernous sinus thrombosis. Findings may include deformity of the internal carotid artery within the cavernous sinus, and an obvious signal hyperintensity within thrombosed vascular sinuses on all pulse sequences.Cerebral angiography can be performed, but it is invasive and not very sensitive. Orbital venography is difficult to perform, but it is excellent in diagnosing occlusion of the cavernous sinus.[9]
Recognizing the primary source of infection (i.e., facialcellulitis, middle ear, and sinus infections) and treating the primary source expeditiously is the best way to prevent cavernous sinus thrombosis.[10]
Broad-spectrum intravenous antibiotics are used until a definite pathogen is found.[citation needed]
Vancomycin may be substituted for nafcillin if significant concern exists for infection by methicillin-resistantStaphylococcus aureus or resistantStreptococcus pneumoniae.[11] Appropriate therapy should take into account the primary source of infection as well as possible associated complications such asbrain abscess, meningitis, orsubdural empyema.
People with CST are usually treated with prolonged courses (3–4 weeks) of IV antibiotics. If there is evidence of complications such as intracranial suppuration, 6–8 weeks of total therapy may be warranted.[citation needed]
All patients should be monitored for signs of complicated infection, continued sepsis, orseptic emboli while antibiotic therapy is being administered.[citation needed]
Anticoagulation withheparin is controversial. Retrospective studies show conflicting data. This decision should be made with subspecialty consultation.[12] One systematic review concluded that anticoagulation treatment appeared safe and was associated with a potentially important reduction in the risk of death or dependency.[13]
Steroid therapy is also controversial in many cases of CST.[14][15][16][17] However, corticosteroids are absolutely indicated in cases ofpituitary insufficiency. Corticosteroid use may have a critical role in patients withAddisonian crisis secondary to ischemia or necrosis of the pituitary that complicates CST.[18][19]
Surgical drainage withsphenoidotomy is indicated if the primary site of infection is thought to be thesphenoidal sinuses.[20]
Cavernous sinus thrombosis has a mortality rate of less than 20% in areas with access to antibiotics. Before antibiotics were available, the mortality was 80–100%. Morbidity rates also dropped from 70% to 22% due to earlier diagnosis and treatment.[citation needed]