**Question:** Following statements regarding cerebral venous sinus are true:

a) Transverse sinus is unequal
b) Cerebral venous thrombosis (CVT) causes enophthalmos
c) CVT causes empty delta sign
d) Communicates with the subdural space

**Core Concept:**
Cerebral venous sinuses are a series of channels within the dura mater that drain deoxygenated blood from the brain to the internal jugular veins. CVT refers to the formation of a blood clot within these veins, potentially leading to various clinical manifestations.

**Why the Correct Answer is Right:**

a) Transverse sinus is unequal: The transverse sinus is a significant cerebral venous sinus, and it is rare for it to be unequal due to its location and function. However, in specific situations, such as sinusitis, inflammation, or venous stasis, the transverse sinus can become dilated, leading to a perception of inequality.

b) CVT causes enophthalmos: Enophthalmos is a condition characterized by the protrusion of the eyeball due to retrobulbar hypotony. CVT can sometimes result in orbital venous hypertension, leading to increased pressure within the retrobulbar space, which can result in enophthalmos.

c) CVT causes empty delta sign: The empty delta sign is a radiological finding characterized by the absence of the opacification of the transverse and sigmoid sinuses on a venous phase of a brain CT angiogram. CVT can lead to the compression or occlusion of these sinuses, leading to the empty delta sign.

d) Communicates with the subdural space: The majority of cerebral veins, including the transverse and sigmoid sinuses, do not directly communicate with the subdural space. However, in specific situations like dural sinus rupture, there can be a communication between the subdural space and the venous system.

**Why Each Wrong Answer is Incorrect:**

a) This statement is incorrect as the transverse sinus is not typically unequal due to its anatomical position and function.

b) CVT can lead to enophthalmos, but the empty delta sign is not specifically related to CVT. The empty delta sign is a result of the compression or occlusion of the transverse and sigmoid sinuses, which can be caused by various etiologies, not limited to CVT.

c) Empty delta sign is a result of the compression or occlusion of the transverse and sigmoid sinuses, not directly caused by CVT.

d) The majority of cerebral veins, including the transverse and sigmoid sinuses, do not directly communicate with the subdural space. This statement is incorrect because a communication between the subdural space and the venous system can occur in certain situations, such as dural sinus rupture.

**Core Concept:**

The cerebral veins, including the transverse and sigmoid sinuses, are part of the venous drainage system in the brain. They drain blood from the brain to the jugular bulb, which then communicates with the internal jugular vein leading to the