Rarely, injury and disruption to the orbit can result in CSF occulorrhea. Less regularly, fractures of the temporal bone (middle ears or mastoid cells) are associated with dural disruption, which can also result in CSF leak through the ears (otorrhea). The cribriform plate, ethmoid bone, and sphenoid sinuses are thin and closely associated with the dura. Anterior skull base fractures are frequently associated with moderate-to-high-velocity impact. Skull base CSF leaks occur when there is an abnormal communication between the subarachnoid space and air space in the paranasal sinuses, nasal cavity, middle ear, or mastoid cells. Ĭraniofacial trauma can lead to varied presentations of CSF leak, determined primarily by injury location and mechanism of action. CSF leak is typically classified into spontaneous/idiopathic, traumatic, and iatrogenic. Iatrogenic causes comprise 16% of CSF leaks, with the last 4% due to varied etiologies. The most common cause of leaking cerebrospinal fluid is a structural compromise secondary to craniofacial trauma, making up 80% of CSF leaks. Ringing in the ear and loss of smell or taste is also possible clinical findings. The most common symptoms are low-pressure (orthostatic) headaches (92%), nausea (54%), and neck pain (43%). It occurs when there is a tear or hole in the dura mater, the meninges' outermost layer that protects the central nervous system, communicating the subarachnoid space and other spaces via meningeal disruption. EtiologyĬerebrospinal fluid (CSF) leak is the escape of the fluid surrounding the brain and spinal cord. Therefore, the presence of signs and symptoms of a CSF leak indicates the need for further evaluation and management. Open communication of the subarachnoid space with CSF leak also presents a pathway for life-threatening CNS infection, including meningitis. A leak can be detrimental to brain blood supply and function and can increase the risk of direct trauma to brain parenchyma due to loss of fluid cushion. This can cause low-pressure headaches, neck pain, ringing in the ear, and occasionally, loss of smell or taste. The CSF leak occurs when there is a tear or hole in the dura mater, the outermost layer of the meninges that protect the central nervous system, communicating the subarachnoid space with the epidural space and, sometimes, with the skin establishing a connexion between the CNS and the external environment. The CSF regulates CNS temperature, cushions the brain and spinal cord, and provides a delicately balanced buoyant force that allows the brain to retain its shape and circulatory integrity despite its weight and lack of intrinsic rigid support. The CSF also forms the blood-CSF barrier (BCSFB) circulation, acting in the removal of waste products and metabolites through its continuous renewal. ![]() ![]() ![]() This volume is defined by equal production and reabsorption rates of approximately 420 to 530 mL/day in adults. The volume of CSF is estimated at 125 mL to 150 mL in the SAS and 25 mL in the ventricular system. ![]() However, much controversy remains regarding the basic CSF physiology, which led some researchers to defy the conventional theory and propose alternative homeostatic mechanisms of CSF regulation. According to Cushing and Weed's seminal theory, the CSF is mainly produced by the choroid plexuses, a network of blood vessels and tissues located within the ventricles of the brain, and circulates throughout the CNS to be finally reabsorbed into the venous sinuses at the level of arachnoid granulation (AGs). It consists predominantly of 99% water, and 1% accounts for electrolytes, proteins, neurotransmitters, and glucose. Cerebrospinal fluid (CSF) is a clear, colorless liquid found in the subarachnoid space (SAS) that fills the neuroaxis cavities and surrounds the central nervous system (CNS).
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