As many traumatic leaks cease spontaneously, it is advisable to wait and watch for a short time. The management of CSF leaks should be tailored according to the underlying etiology. Similarly, among the non-traumatic causes with normal ICP, there is usually a congenitally bone and dura defect or one secondary to infective or inflammatory pathologies. One such condition is idiopathic intracranial hypertension, frequently in young to middle-aged obese women and is associated with sellar floor erosions resulting in spontaneous CSF rhinorrhoea. Īmong the non-traumatic causes of high-pressure CSF leaks, there is generally thinning and resorption of the bone at the skull base and thinning of the dural layer, which over time results in communication with the subarachnoid space. Penetrating injuries are associated with a higher rate of CSF leak and more complications like meningitis and higher mortality. However, not all skull base fractures result in CSF leak, which depends on the interplay of several variables like raised ICP, arachnoidal disruption, dural injury, and the size of the bony defect. In these middle cranial fossa cases, rupture of the tympanic membrane is an essential pathophysiologic intermediate for otorrhea to manifest. On the other hand, head blunt trauma involving the middle cranial fossa can cause rhinorrhea or otorrhea. Out of these, fracture of the frontal sinus is the most common culprit causing CSF leak.
Similarly, spinal CSF leaks may follow traumatic or iatrogenic communication between spinal subarachnoid space and the external environment.Īmong the traumatic causes of CSF leak, blunt trauma is more common than penetrating injuries, affecting the anterior skull base more frequently than the middle or posterior skull base. A small proportion of cases are caused by non-traumatic etiologies, which may be associated with raised ICP like hydrocephalus or intracranial space-occupying lesion or normal ICP like congenital defects, focal atrophy, or post-infection bony erosions. Other common causes include iatrogenic defects following neurosurgical procedures like opening the sphenoid sinus in trans-sphenoidal surgeries or opening the mastoid air cells in posterior fossa surgeries. Following motor vehicle accidents, blunt trauma to the head can lead to skull base fractures, presenting as CSF rhinorrhoea. The most likely etiology underlying these abnormal defects is traumatic, out of which the most common mechanism is motor vehicle accidents, especially in moderate to high-velocity trauma. The communication site may exist at the anterior skull base, including frontal and ethmoidal air cells, middle skull base, including sphenoid or mastoid air cells, and the posterior fossa, including the mastoid air cells and the middle ear. The leaks often present as rhinorrhea unless the tympanic membrane is defective and will present as otorrhea. Ĭranial CSF leaks can manifest either in the form of rhinorrhea or otorrhea. Similarly, CSF is absorbed in multiple sites, with dural venous sinuses being the major drainage site via arachnoid granulations followed by choroid plexus and glymphatic system. Apart from this, interstitial space, ependyma, and dural sleeves of the spinal nerve roots also contribute to the total CSF turnover. According to the current understanding, the production of CSF is from multiple sources, primarily from the choroid plexus of the lateral and fourth ventricles. The currently accepted CSF flow system comprises pulsatile CSF flow, lymphatic system, capillary exchange, and the traditional ventricular-cisternal system. However, this model seems inadequate to explain the pathophysiological mechanisms of various CSF flow-related disorders based on recent literature. The traditional concept of CSF formation, distribution, and absorption was previously based on the bulk flow model. It also predisposes the brain and spinal cord to the external environment increasing the risk of meningitis, ventriculitis, and arachnoiditis. Such conditions might be associated with fractures in the skull base, congenital bony defects, or might be associated with raised intracranial pressure (ICP). In various disorders that present with CSF leak, the loss of this protective nutrient-rich layer can injure the function of the brain and the spinal cord.
This protective cushion circulates within the ventricular system and the subarachnoid space around the brain and the spinal cord, which helps to provide the buoyancy to counteract various shear and stress encountered during the movement of the skull and vertebral column. The cerebrospinal fluid (CSF) acts as a nourishing and protective layer surrounding the central nervous system.
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