f Post graduate mcqs and discussion : Lateral sinus thrombophlebitis

Saturday, March 24

Lateral sinus thrombophlebitis

It is an inflammation of inner wall of lateral venous sinus with formation of an intrasinus thrombus.

Fig: lateral sinus thrombophlebitis 



Aetiology :

It occurs as a complication of acute coalescent mastoiditis , masked mastoiditis or chronic suppuration of middle ear and cholesteatoma .

Pathology:

The pathological process can be divided into the following stages :

A. Formation of perisinus abscess :  abscess form in relation to outer dural wall of sinus . It has been destoryed by coalescent bone erosion or cholesteatoma .

B. Endophlebitis and mural thrombosis formation : inflammation spread to inner wall of the venous sinus with deposition of fibrin , platelets and blood cells leading to thrombus formation with in the lumen of sinus. 

C. Obliteration of sinus lumen and intrasinus abscess : mural thrombus enlarges to occlude the sinus lumen completely. Organisms may invade the  thrombus causing intrasinus abscess which may release infected emboli into the blood stream causing septicaemia.

D. Extension of thrombus : though central part of thrombus breaks down due to intrasinus abscess,  thrombotic process continues both proximally and distally . Proximally it may spread to confluence of sinuses and to superior saggital sinus  or cavernous sinus , and distally into mastoid emissary vein , to jugular bulb or jugular vein .


Clinical features :

Hectic picket fence type of fever with rigor : due to septicaemia,  often coinciding with release of septic emboli into blood stream . Usually accompanied by chills and rigor . Clinical pictures resembles malaria but lack of regularity.

Headache

Progressive anaemia and emaciation.

Griesingeri' s sign: due to thrombosis of mastoid emissary vein . Oedema appers over the posterior part of mastoid. 

Papilloedema : it's presence depends on the obstructions  of venous return.  It is often seen when right sinus is thrombosed or when clot extend to superior saggital sinus. Fundus may shows blurring of disc margin , retinal haemorrhage or dilated veins .

Tobey - Ayer test:  this is to records CSF pressure by manometer and to see the effect of manual compression of one or both jugular veins .

Compression of veins on the thrombosed side produces no effect while compression of vein on healthy side produces rapid rise in csf pressure which will be equal to bilateral compression of jugular vein.

Crowe-Beck test : pressure on jugular veins on healthy side produces engorgement of retinal vein and supraorbital veins .

Tenderness along the jugular veins : this is seen when thrombophlebitis extends along the jugular veins . There may be associated enlargement and inflammation of jugular chain of lymph nodes and torticollis. 


Investigation :

Blood smear is done to rule out malaria

Blood culture is done to find the causative organisms. Culture should be done at the time of chill when the organism enter into blood circulation.

CSF examination -CSF is normal except for rise in pressure.  It also helps to exclude meningitis. 

X-rays mastoid: May shows clouding of air cells (acute mastoiditis) or destruction of bone ( cholesteatoma)

Imaging studies : shows sinus thrombosis by typical delta sign. It is triangular area with rim enhancement and central low density area is Seen in posterior cranial fossa on axial cuts . MR venography is useful to assess progression or resolution of thrombosis. 


Culture and sensitivity of ear swab.


Complications :

Meningitis and subdural abscess
Cerebellar abscess
Cavernous sinus thrombosis
Ottic hydrocephalus when thrombus extends to saggital sinus via confluens of sinuses.
Septicaemia and pyaemic abscess in the lungs , bone , joints or subcutaneous tissue. 

Treatment :

A. Intravenous antibacterial therapy :

B . Mastoidectomy and exposure of sinus :  A complete cortical or modified radical mastoidectomy is performed,  depending on whether  sinus thrombosis has complicated acute or chronic middle ear disease.  Sinus bony plate is removed to expose the dura and drain the perisinus abscess. 

C. Ligation of internal jugular vein: It is indicated when antibiotics and surgical treatment have failed to control emboli phenomenon and rigors,  or tenderness and swelling along jugular vein is spreading. 


D. Anticoagulant therapy : it is rarely required and used when thrombosis is extending to cavernous sinus .

E. Supportive treatment : repeated blood transfusions may be required to combat anaemia and improve patients resistance.