Cavernous sinus

Orbital cellulitis or abscess, periorbital cellulitis, meningitis, cavernous sinus thrombosis, ethmoid or frontal sinus erosion, chronic sinusitis, and exacerbation of asthma or bronchitis... 

Suggested Alternatives for Differential Diagnosis Meningitis, basilar artery blood clots (thrombosis), cardioembolic stroke, cavernous sinus syndromes, cerebral venous blood clots (thrombosis), confusional states and acute memory disorders, epileptic and epileptiform encephalopathies, febrile seizures, haemophilus meningitis, intracranial hemorrhage, leptomeningeal carcinomatosis, subdural pus (empyema), or bruise (hematoma). 

The control of metabolism, growth, and reproduction is mediated by a combination of neural and endocrine systems located in the hypothalamus and pituitary gland. The pituitary weighs about 0.6 g and rests at the base of the brain in the bony sella turcica near the optic chiasm and the cavernous sinuses. The pituitary consists of an anterior lobe (adenohypophysis) and a posterior lobe (neurohypophysis) (Figure 37-1). It is connected to the overlying hypothalamus... 

Thrombosis of the cavernous sinus is characterized by proptosis, chemosis, impaired vision and ophthalmoplegia. If it is not septic, prognosis is good because of collateral drainage and spontaneous recanalization. The same symptoms, with the exception of a possible bruit, may result from arteriovenous shunting in carotid-cavernous fistulae. The treatment of choice in this case is endovascular occlusion (thrombosis ) of the cavernous sinus. 

Fig. 18.1. Venous anatomy in digital subtraction angiography (DSA) in lateral projection. FV, frontal veins PV, parietal veins OV, occipital veins SSS, superior sagittal sinus ISS, inferior sagittal sinus TS, transverse sinus SIS, sigmoid sinus IJV, internal jugular vein SS, straight sinus CS, confluens sinuum VL, vein of I.abbe SV, sylvian vein CS, cavernous sinus VG, vein of Galen 1CV, internal cerebral vein IJV, internal jugular vein...

The internal carotid artery starts as the carotid sinus at the bifurcation of the common carotid artery at the level of the thyroid cartilage. It runs up the neck, without any branches, to the base of the skull where it passes through the foramen lacerum to enter the carotid canal of the petrous bone. It then runs through the cavernous sinus in an S-shaped curve (the carotid siphon) pierces the dura and exits just medial to the anterior clinoid process. It then bifurcates into the anterior cerebral artery and the larger middle cerebral artery. 

The ophthalmic artery is the first major branch of the internal carotid artery and arises in the cavernous sinus. It passes through the optic foramen to supply the eye and other structures in the orbit. 

The meninges are supplied by branches of the external carotid artery, internal carotid artery and vertebral arteries. The most prominent branches from the external carotid artery are the middle meningeal artery and tributaries of the ascending pharyngeal and occipital arteries. Most of the branches from the internal carotid artery arise near the cavernous sinus and from the ophthalmic artery in the orbit. Branches from the vertebral artery arise at the foramen magnum. There are numerous meningeal anastomoses between these small arteries. 

Septic thrombosis of the cavernous sinuses. Archives of Internal Medicine 161 2671-2676... 

Unmyelinated fibers emerge from the superior cervical ganglion and coiu se toward the cavernous sinus by... 

Figure 8-1 The oculosympathetic pathway. Note its origin in the hypothalamus and its course through the brainstem and cervical spinal cord (central or first-order neuron), the upper thorax and lower neck (pregangUonic or second-order neuron), and upper neck, middle cranial fossa, cavernous sinus, and orbit as it finally reaches Muller s muscle of the lid and the iris dilator muscle (postganglionic or third-order neuron), (a. = artery n. = nerve.) (Reprinted with permission from Glaser JS.The pupils and accommodation. In Duane TD, Jaeger EA, eds. Clinical ophthalmology. Hagerstown, MD Harper Row, 1987.)...

Abnormalities of the internal carotid artery Unilateral vascular headache syndromes Direct or indirect trauma Spontaneous or traumatic occlusion Aneurysms Atherosclerosis Spontaneous dissection Lesions involving the middle cranial fossa and cavernous sinus Basal skull fractures... 

Van Johnson E, Kline LB, Julian BA, Garcia JH. Bilateral cavernous sinus thrombosis due to mucormycosis. Arch Ophthalmol 1988 106(8) 1089-92. 

Finsterer J, Artner C, Kladosek A, Kalchmayr R, Redtenbacher S. Cavernous sinus syndrome due to vaccination-induced giant cell arteritis. Arch Intern Med 2001 161(7) 1008-9. 

Ideally, there should be no venous enhancement. Nevertheless, except for specific indications such as cavernous sinus aneurysm and arteriovenous malformation (AVM) assessment, this is seldom clinically limiting. Z-direction coverage, in-plane and longimdinal resolution, and signal-to-noise ratio should be maximized, while radiation dose, total amount of contrast administered, and acquisition slice thickness should be minimized. Our routine stroke CTA protocol for 16- or 64-slice MDCT scanners covers from the great vessel origins at the aortic arch to the cranial vertex. 

Since detection of an acute intracranial embolus is our first priority, we start the scan at the vertex of the skull and image caudally to the level of the aortic arch. Hence, the circle of Willis images have the least venous contamination as well as the most uniform arterial opacification, which is especially critical in the region of the cavernous sinus (Fig. 4.17). The presence of venous opacification in the neck is not detrimental to image quality as long as there is sufficient arterial opacification. Furthermore, delayed scanning through... 

Time-resolved CTA could improve visualization of currently difticult-to-detect lesions, such as cavernous sinus aneurysms and small arterial venous malfor-mations/fistulae, as these could be visuahzed with greater temporal resolution during arterial, capillary, and venous phases of contrast enhancement. In fact, dedicated studies could display a temporally parsed image, which could mirror the temporal resolution of the conventional cerebral catheter angiogram. 

Macroadenomas (>1 cm) occupy the pituitary fossa and may cause visual abnormalities when they put pressure on the optic chiasm. Macroadenomas also tend to invade the cavernous sinus and erode the bony floor. The extent of the tumor can be determined by means of contrast-enhanced MR imaging. 

The question as to why cavernomas predominantly occur in the central nervous system (CNS), as well as in the spinal cord, skin, and eyes (Sarraf et al. 2000), is still unresolved. Other, rare locations include the cerebral ventricles (Reyns et al. 1999), cranial nerves (Ferrante et al. 1998), the cavernous sinus (Bristot et al. 1997), or subarachnoid space (Kim M et al. 1997). There are also reports on an extradural location (Porter et al. 1999). 

Bristot R, Santoro A, Fantozzi L, Dellini R (1997) Cavernoma of the cavernous sinus case report. Surg Neurol 48 160-163... 

Although this study proves the role of increased vasogenic activity in the development of human DAVM, it does not provide information regarding the cause of such increased activity. As DAVMs, particularly those involving the cavernous sinus, have... 

DAVMs may occur anywhere within the cranium or in the spinal column. Intracranial DAVMs are located either in the anterior cranial fossa on or around the ethmoid groove (Fig. 4.3,1), in the middle cranial fossa at the cavernous sinuses (Fig. 4.3,2), in the posterior fossa at the transverse (Fig. 4.3,3) or the sigmoid (Fig. 4.3,4) sinuses, at the confluens sin-uum (Fig. 4.3,5), or around the foramen magnum... 

Fig. 4.3. Typical locations of intracranial dural arterial malformations. 1, anterior fossa 2, cavernous sinus 3, transverse sinus 4, sigmoid sinus 5, confluens sinuum 6, foramen magnum 7, tentorial incisura 8, base of the tentorium 9, straight sinus and vein of Galen...

Cavernous sinus Contralateral cavernous sinus, ophthalmic veins, inferior petrosal sinus, temporal veins... 

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