What Is a CSF Leak?

Cerebrospinal fluid leakage can be divided into traumatic and non-traumatic according to the etiology. Trauma is the most common and is mainly caused by trauma and skull base sinus surgery. Non-traumatic cerebrospinal fluid leakage can be divided into: normal intracranial pressure (caused by congenital malformations, local atrophy, and cranial osteomyelitis); increased intracranial pressure (caused directly or indirectly by intracranial tumors, or by obstructive Caused by traffic hydrocephalus). According to the leakage site, it can be divided into cerebrospinal fluid nasal leakage, cerebrospinal fluid ear leakage, and cerebrospinal fluid skin leakage.

Ma Xinlong	(Resident)	Department of Neurosurgery, Xuanwu Hospital, Capital Medical University
Du Jianxin	(Chief physician)	Department of Neurosurgery, Xuanwu Hospital, Capital Medical University

The cerebrospinal fluid cavity communicates with the extracranial, and those who have cerebrospinal fluid leakage are called cerebrospinal fluid leakage. Cerebrospinal fluid loss caused headache, more medical treatment, more than 1 month still have fluid leakage can be treated with surgery. The main symptom is that the ears and noses shed fluid after traumatic head injury. Cerebrospinal fluid leakage can be divided into: traumatic, accidental or iatrogenic and spontaneous. Trauma is predominant and spontaneity is rare.

Western Medicine Name: Cerebrospinal fluid leak
Affiliated Department: Surgery-Neurosurgery

Disease site: Brain
Main cause: trauma
Contagious: Non-contagious

Cerebrospinal fluid leakage clinical classification

Causes of cerebrospinal fluid leakage

Cerebrospinal fluid flows into the nasal cavity through congenital or traumatic congenital or traumatic bone defect, rupture or thinning of the anterior cranial fossa floor, middle cranial fossa floor, or other parts, which is called cerebrospinal fluid rhinorrhea. Among various cerebrospinal fluid nasal leaks, trauma is most common. Cerebrospinal fluid ear leaks are often caused by the middle cranial fossa fracture involving the tympanic cavity. A fracture of the middle cranial fossa floor causes the meninges in the upper middle ear to be torn and rupture the tympanic membrane, which can cause cerebrospinal fluid leakage from the external auditory canal to form cerebrospinal fluid ear leaks. Ear leaks and nasal leaks mainly indicate the possibility of skull base fractures, and infection may be transmitted from the ears or nose to the meninges, which may be associated with meningitis.

Cerebrospinal fluid leakage pathogenesis and pathophysiology

Cerebrospinal fluid leakage is caused by the fracture of the skull while tearing the dura mater and the arachnoid membrane. As a result, the cerebrospinal fluid flows from the fracture slit through the nasal cavity, external auditory canal, or open wound, allowing the cranial cavity to communicate with the outside world and form a leak. Escape into the skull and cause pneumonia.

The ethmoidal plate and the posterior frontal sinus bone plate are very thin and closely connected with the dura mater. If the vertebral plate and the dura mater rupture at the same time, a cerebrospinal fluid rhinorrhea will occur. Fractures of the middle cranial fossa can damage the upper wall of the larger sphenoid sinus and cause cerebrospinal fluid rhinorrhea. Cerebrospinal fluid ear leaks are usually caused by the middle cranial fossa fracture involving the tympanic cavity. Because the rock bone is located at the junction of the cranial and posterior fossa, regardless of the middle or posterior fossa fracture of the rock bone, as long as the middle ear cavity is injured, it can be bloody. Cerebrospinal fluid enters the tympanic cavity. The cerebrospinal fluid leakage caused by the middle ear mastoid canopy or the eustachian tube bone fracture can flow through the eustachian tube to the nasal cavity and become cerebrospinal fluid ear and nose leakage. Iatrogenic cerebrospinal fluid rhinorrhea is caused by surgery, such as middle turbinate resection or ethmoid sinus resection, which damages the ethmoid bone and ethmoid plate, and transsphenoidal pituitary tumor resection. Nontraumatic cerebrospinal fluid nasal leaks are rare and often caused by tumors or hydrocephalus. Spontaneous cerebrospinal fluid rhinorrhea is rare.

Cerebrospinal fluid wound leakage, that is, skin leakage, are almost all caused by improper handling of open craniocerebral injury in the early stages. They are more common in firearm penetrating injuries, due to poor repair of the dura mater or due to poor wound healing. If the cerebrospinal fluid leakage comes directly from the ventricle penetrating injury, a large amount of cerebrospinal fluid is often lost. Not only is the general condition low, but it also often causes severe meningitis and encephalitis, especially in children. Debridement and repair must be performed in time. Cerebrospinal fluid flows out of the nasal cavity, ear canal, or open wound, which is a serious complication of craniocerebral injury.

Cerebrospinal fluid leakage clinical manifestations

At the time of injury, bloody fluid flows from the nasal cavity, ears, the center of the trace is red and the surrounding is clear, or the colorless liquid from the nostril becomes dry without crusting, and the flow increases when you lower your head and press the jugular vein. Cerebrospinal fluid is constantly draining and causing headaches. Or there is less leakage, but the pillow is found wet in the morning. There are also only repeated intracranial bacterial infections, and rhinorrhea is not obvious. The general incidence is mostly after traumatic brain injury, surgery or paranasal sinus surgery. A few patients have only a history of minor traumatic brain injury or nasal leakage after sneezing.

Cerebrospinal fluid leakage diagnosis and differential diagnosis

Cerebrospinal fluid leak diagnosis

Cerebrospinal fluid rhinorrhea is determined based on clinical manifestations. According to the quantitative analysis of glucose, its content must be above 1.7mmol / L (30mg%), and the diagnosis of cerebrospinal fluid can be confirmed by excluding the contamination of the tear machine blood. Except for ear and nose leaks, in addition to asking for symptoms such as deafness, ear tightness, and dizziness, otoscopy can be performed.

Determining the location of the fistula: Clinical observation: When the leaking fluid flow is fast and fast, the fistula is often large and may be connected with the sphenoid sinus and the skull base. For those who leak from one side of the nostril, the fistula is often on that side. Nasal endoscopy is often used to diagnose the location of cerebrospinal fluid nasal leaks. A large amount of cerebrospinal fluid nasal leaks can be seen from the clear fluid outflow or pulsatile overflow. Compression of the ipsilateral internal jugular vein is helpful for the diagnosis of cerebrospinal fluid nasal leaks. In addition, the use of imaging methods: high-resolution CT or MRI cerebrospinal angiography can also help localize the diagnosis of cerebrospinal fluid leakage.

Differential diagnosis of cerebrospinal fluid leakage

The diagnosis is not difficult.For example, when there is less cerebrospinal fluid and there is more blood, it is often difficult to distinguish between simple bleeding and simple bleeding.At this time, the discharged fluid can be dripped on absorbent paper or gauze.If you quickly see a circle of water around the blood stain that is moistened by water A ring-shaped red halo can be identified as mixed with cerebrospinal fluid. Intermittent or small leaks should be distinguished from allergic rhinitis or vasomotor rhinitis. If the eardrum is ruptured, the fluid flows out through the external ear canal, and when the eardrum is intact, the cerebrospinal fluid can flow through the eustachian tube to the pharynx, and even back to the nasal cavity from the posterior nasal cavity and then overflow from the nostril, which is similar to the nasal leak caused by anterior fossa fracture, which is easier to misdiagnose Should be noted. ^[1]

Cerebrospinal fluid leakage disease treatment

Cerebrospinal fluid leakage medical treatment

This disease is mostly treated by medical treatment. Patients should take a rest in the head and use antihypertensive drugs (mannitol, etc.) to create conditions for fistula healing. At the same time, avoid coughing, sneezing and exertion, so as to avoid exacerbating cerebrospinal fluid loss, limiting water consumption and Salt intake to prevent constipation. Antibiotics prevent retrograde intracranial infection. The nose is not flushed or stuffed.

Intranasal drug corrosion therapy is suitable for those with fistulas located on the ethmoidal sieve and less flow. The method is to wipe the mucous membrane at the edge of the fistula with 20% silver nitrate, causing wounds to promote healing.

Cerebrospinal fluid leakage surgery

Those who still have fluid leakage for more than 1 month can be treated with surgery. Spontaneous rhinorrhea is rarely stopped by itself, and early surgery is generally advocated.

Surgical indications:

There is Qi brain (gas accumulation in the cranial cavity), brain tissue prolapse, and foreign bodies in the brain;

Cerebrospinal fluid leakage caused by tumors;

Complicated recurrent purulent meningitis.

Surgical methods: The choice of surgical methods is based on the preoperative positioning diagnosis. The following two methods are available.

Transcranial repair: Cerebrospinal fluid nasal leaks through the base of the anterior skull can be treated with unilateral or bilateral frontal lobe craniotomy. There are two types of epidural and subdural approaches. Either the epidural approach or the subdural approach will cause deodorization. If possible, try to take a unilateral approach to the approach. The leak is in the saddle, which is difficult to reach through frontal surgery. For the middle cranial fossa-sphenoid sinus leak caused by excessive vaporization of the lateral sphenoid sinus, it is possible to improve the wing-point approach, and it is required to be as close to the skull base as possible in order to explore the sphenoid wings.

Extracranial repair can't actually suture the dura mater directly, it mainly depends on stuffing, and it has poor aseptic conditions, and it is easy to relapse after surgery. Because there are relatively many patients with nasal leakage after transsphenoidal pituitary tumor surgery, and sphenoid sinus leakage is inconvenient for frontal surgery, transsphenoidal repair is more commonly used in neurosurgery. Transsphenoidal repair is only applicable to the situation where the sphenoid sinus is located before surgery. If the patient has a saddle area or an empty saddle, the surgery can be treated together, and if necessary, combined with craniotomy

Ear leaks are basically treated in the same way as nasal leaks. The external ear canal was swabbed with alcohol and covered with sterile gauze.

The principle of skin leakage treatment is mainly to treat the primary disease. If necessary, perform cerebrospinal fluid shunt to reduce intracranial pressure, and then deal with skin leakage. ^[2]

Prognosis of cerebrospinal fluid leakage

The surgical effect of cerebrospinal fluid rhinorrhea depends to a large extent on the accuracy of preoperative localized diagnosis.HRCT and MRC will gradually replace cerebrovascular angiography and radionuclide brain cistern imaging combined with nasal separation because of their advantages of accuracy, speed, and non-invasiveness Dow cotton test radioactivity measurement has become the preferred method of positioning inspection, and will be improved with the advancement of technology. The transfrontal epidural approach is more advantageous than the subdural approach because it has a wide range of applications, is effective, and has less damage. It will be gradually promoted and popularized. ^[3]