Venous Sinus Syndrome (aka Cavernous sinus syndrome) is an umbrella term for resultant signs due to various causes affecting the cavernous sinus. The most common and clinically significant of which is venous sinus thrombosis (aka cavernous sinus thrombosis).
The cavernous sinus is one of the dural venous sinuses. These venous channels drain the cerebral veins. In the case of the cavernous sinus, the veins that drain into it are mainly the ophthalmic veins.
To understand the clinical presentation of cavernous sinus syndrome, it is important to understand the anatomy of cavernous sinus. The cavernous sinus is unusual because it is a venous structure, through which other anatomical structures pass.
- Anatomical relations of cavernous sinus: cavernous sinus is located laterally to sella turcica containing pituitary gland.
- Contents: Within the cavernous sinus, there are following structures:
- Internal carotid arteries
- Nerves –
- CN 3 (oculomotor nerve)
- CN 4 (trochlear nerve)
- CN 5a & 5b (ophthalmic and maxillary branches of trigeminal nerves)
- CN 6 (abducens nerve)
- Post-ganglionic sympathetic nerve fibres
Signs and symptoms
- Headache – classically acute onset, often unilateral, with photophobia
- Ophthalmoplegia and/or diplopia
- Due to lesions on nerves of eye movements (CN 3, CN 4, CN 6)
- Usually unilaterally, later progressing to both eyes
- Other Neurological signs – may be absent or can be wide range of signs including hemiparesis, lower limb weakness, aphasia, ataxia
- Facial pain
- Increased pressure within cavernous sinus. Also, the first two branches of trigeminal nerves may be affected
- Pulsatile proptosis
- Indicative of internal carotid artery aneurysm
- Horner’s syndrome
- This is due to post-ganglionic sympathetic nerve fibres being affected
Important causes of cavernous sinus syndrome
- Cavernous sinus thrombosis – most common presentation – usually secondary to a local infection spreading from the nose, ears, sinuses or teeth.
- Carotid-cavernous venous fistula – where the carotid artery dissects at the point at which is passes through the cavernous sinus.
- Infection – localised infections – e.g. in the nose can lead to cavernous sinus thrombosis
- Pituitary adenoma
- Metastatic tumours
- Aneurysm of internal carotid artery within cavernous sinus
Often the diagnosis of cavernous sinus syndrome (and cavernous sinus thrombosis) is quite far down the list of possible differentials. In a patient presenting with headache, with or without visual signs, relevant investigations would include:
- Blood tests – FBC, UEC, CRP, ESR. Give an indication of an infective cause, may help differentiate facial pain cases (ESR particularly useful in helping determine if temporal arteritis).
- Lumbar puncture
- CT would usually be first line in the acute presentation due to its availability, but may miss some causes. Findings on CT may include evidence of sinusitis, filling defects of the venous sinus or abnormality of the superior ophthalmic vein. There may be an area of infarction visible which is not compatible with an aterial cause.
- MRI if available / if CT normal but diagnosis still suspected. An MR venogram can detect if there is thrombus in the sinus, and MRI can also see if there is any compression of the internal carotid artery.
- Consider broad spectrum antibiotics if infective cause suspected
- Common causative agents include staphylococcus and streptococcus
- Typical regimen might include
- Anticoagulation – usually with warfarin and heparin cover for the first few days
- Surgery may be considered