Most cerebrospinal fluid leaks are caused by trauma, some are due to medical factors of surgery, and spontaneous cerebrospinal fluid leaks are very rare.
I. What is traumatic cerebrospinal fluid leak?
Cerebrospinal fluid leak is a fracture or defect in the skullcap and/or skull base caused by various reasons, which ruptures the dura and arachnoid membranes and causes cerebrospinal fluid to flow from the fracture gap through the nasal cavity, external auditory canal or open wound, allowing the cranial cavity to communicate with the outside world.
Second, what types of cerebrospinal fluid leakage are there? How to cure?
1. According to the etiology, it is divided into three types: spontaneous (congenital and acquired), medical and traumatic.
2. It can be divided into cerebrospinal fluid nasal leakage, cerebrospinal fluid ear leakage or cerebrospinal fluid wound leakage according to the location.
What kind of people are prone to cerebrospinal fluid leakage?
1. Cerebrospinal fluid leakage after craniocerebral trauma is usually caused by skull base fracture, and it is rare to occur in skull cap fracture.
2. It is more common in adults, and the incidence in children is significantly lower than that in adults because the skull is softer and more elastic and the paranasal sinuses are not fully developed.
Why is it easy to get cerebrospinal fluid leakage after trauma? Why does water come out of the nose?
1. The bones at the base of the anterior and middle fossa of the skull are thin, especially the base of the anterior fossa of the skull is uneven, and there is only a thin layer of bone flap separating the nasal cavity and the orbit, and there are many sieve holes on the sieve plate, which are prone to fracture under external force, and cerebrospinal fluid leakage can occur if the dura is ruptured at the same time.
The arachnoid membrane at the sieve plate protrudes into the sieve hole with the olfactory filament, and the dura and arachnoid membrane are easily torn when the fracture passes through the sieve plate.
The base of the anterior cranial fossa is adjacent to the frontal sinus, butterfly sinus and sieve sinus, and the middle cranial fossa has the middle ear cavity and the posterior mastoid; when the fracture involves the paranasal sinus and is accompanied by damage to the mucosa, dura and arachnoid membrane, there can be cerebrospinal fluid nasal leakage; when the fracture involves the middle ear tympanic cap, there can be cerebrospinal fluid ear leakage; if the tympanic membrane is not broken and there is fluid in the tympanic cavity, cerebrospinal fluid can flow into the nasal cavity along the eustachian tube and there can be cerebrospinal fluid nasal leakage.
4. The arachnoid pool at the base of the skull and the base of the brain are adjacent to each other, and cerebrospinal fluid tends to accumulate there, which can easily cause cerebrospinal fluid leakage.
5. Cerebrospinal fluid wound leakage is mostly caused by cranial penetrating injuries, often associated with incomplete early debridement and imperfect dural repair, especially in those with ventricular penetrating injuries.
V. What are the manifestations of cerebrospinal fluid leakage?
1. Acute cerebrospinal fluid leak mostly appears within 48 hours after injury, gradually changing from bloody cerebrospinal fluid to clear, and most of the leaks close on their own within 1 week; a few appear only weeks or months or even years after injury, called delayed cerebrospinal fluid leak, mostly due to force, coughing, nose blowing and other factors that suddenly increase intracranial pressure, causing the leak to occur at the rupture.
2. In some patients with impaired consciousness and supine position, cerebrospinal fluid leakage can flow down the posterior pharyngeal wall, which is insidious and can lead to intracranial infection; if the patient has direct or indirect violent head injury, there is no indication of cerebrospinal fluid leakage at the initial stage, and then signs of intracranial infection appear, internal open cranial trauma should also be highly suspected.
3. Cerebrospinal fluid nasal leakage is mostly seen in anterior cranial fossa base fracture, which can cause subserosal hemorrhage and submembranous hemorrhage of the globus coeruleus and gradual appearance of purple-blue, delayed subcutaneous bruising of eyelid “panda eye” sign a few hours after injury, which can be combined with air cranium, unilateral or bilateral olfactory impairment, intraorbital hemorrhage and protrusion of eyeball, different degrees of visual impairment, pulsatile hemorrhage, fatal oral Nose bleeding. It is usually manifested as increased leakage when sitting up, head down, especially in the early morning after waking up, and reduced or stopped when lying down. Cerebrospinal fluid often flows into the pharynx through the posterior nasal passage when lying in the supine position.
4. Fractures of the temporal bone and mastoid in the middle fossa of the skull often cause cerebrospinal fluid leakage from the ear, and bloody cerebrospinal fluid can flow into the tympanic cavity if the middle ear cavity is injured. Facial palsy, vertigo, balance dysfunction, III, IV, VI, V1 cerebral nerve palsy, internal carotid artery pseudoaneurysm or cavernous sinus arteriovenous fistula; fracture involving the pterygoid saddle and dorsal saddle may cause rupture of the pterygoid sinus with nasal leakage or bruising and swelling of the pharyngeal wall; Battle’s sign (delayed petechiae in the postauricular mastoid area) is common in temporal bone fractures.
5. Posterior cranial fossa fractures involving the slope may cause leakage of cerebrospinal fluid into the pharyngeal wall due to weakness of the mucosa of the pharyngeal wall.
6. Cerebrospinal fluid wound leakage is commonly caused by open cranial trauma in the skull cap, while it is rarely seen due to skull base fracture; the former is almost entirely caused by improper initial treatment of open cranial trauma, mostly seen in firearm cranial penetrating injury, and also seen in large amount of cerebrospinal fluid outflow after artificial dural rejection.
How to diagnose cerebrospinal fluid leakage?
Cerebrospinal fluid leakage occurs in 1/4~1/2 of anterior cranial fossa base fractures. For diagnosed or suspected anterior, middle and posterior cranial fossa base fractures with loss of smell, hearing loss, peripheral facial palsy and vision loss, attention should be paid to observe whether there is outflow of colorless and clear fluid from the nose, eyes, ears and posterior pharyngeal wall.
2. The effluent is usually non-viscous fluid containing glucose, highly suggestive of cerebrospinal fluid when the glucose content is greater than 30 mg/dl; the lack of reliability of the qualitative sugar test paper test; protein electrophoresis combined with immunofixation of transferrin against iodoxyanisole helps to identify cerebrospinal fluid; the presence of light-colored fluid on the outer edge of the blood stain also helps to make the diagnosis.
3. Cranial radiographs can determine skull base fractures, especially whether the fracture line crosses the sphenoid sinuses or rock bones, and fluid accumulation in the paranasal sinuses or fluid-filled papillary humeri is often seen.
4. Cranial CT can be used to observe the skull base fracture by adjusting the bone window, which can help to detect intracranial pneumatization and brain injury.
5. Skull base fracture is mostly diagnosed by its four major clinical features: ① cerebrospinal fluid spillage and leakage; ② delayed petechiae in adjacent soft tissues; ③ adjacent cranial nerve injury; ④ combined with different degrees of cerebral contusions.
VII. How is cerebrospinal fluid leakage treated?
1. Overview
About 80% of traumatic cerebrospinal fluid leaks stop on their own within 1 week after the injury, and a few people who do not heal after more than 2 weeks of conservative treatment should consider surgical treatment, which generally has a good prognosis.
2. Non-surgical treatment
(1) Bed rest, head elevation 30°, affected side position.
(2) Clean the nasal cavity and external auditory canal, and after disinfection, gently fill them with sterile cotton balls and replace them immediately after infiltration, in order to keep the cerebrospinal fluid flowing smoothly to prevent retrograde infection.
(3) Avoid coughing, nose blowing, exertion and other actions that increase cranial hypertension and make it easy for the nasopharyngeal fluid to flow back into the skull.
(4) Keep bowel and urine flowing smoothly.
(5) Adults strictly limit fluid intake to about 1500ml, also acetazolamide (acetazolamide, acetazolamide) to inhibit cerebrospinal fluid secretion; mannitol, furosemide to reduce intracranial pressure.
(6) Those whose leakage does not stop within 3 days may consider lumbar subarachnoid drainage for 3~7 days; note that the drainage bag is located at the shoulder level and should not be drained too fast; also note that continuous lumbar puncture drainage has the risk of leading to cerebrospinal fluid reflux and pathogens entering the skull, which may increase the chance of infection and should be cautious.
(7) Prophylactic application of antibiotics is still controversial.
3. Surgical treatment
(1) Traumatic cerebrospinal fluid auricular and nasal leaks that do not heal spontaneously with early conservative treatment should be considered for cerebrospinal fluid leak repair after 10-14 days; in general, only 2.4% of traumatic cerebrospinal fluid leaks require surgical treatment.
(2) Indications for early surgery ① cerebrospinal fluid incisional leakage (skin leakage); ② skull fracture fracture more than 3 mm; ③ cerebrospinal fluid leakage does not decrease after 1 week; ④ concurrent meningitis and chronic rhinitis, after infection control; ⑤ persistent intracranial pneumothorax with occupying effect, suspected to be tension pneumothorax; ⑥ extensive frontal bone fracture involving the paranasal sinuses; ⑦ late or recurrent leakage occurring 2 weeks after the injury; ⑧ Open craniocerebral trauma or intracranial hematoma combined with cerebrospinal fluid leakage can be surgically repaired in one stage according to the condition.
(3) Intracranial repair method – cerebrospinal fluid nasal leak repair ① Most cerebrospinal fluid nasal leak is caused by fracture of septal sinus or frontal sinus, one side of nasal leak mostly comes from the fracture of the sinus on the same side, which can be craniotomized through the frontal bone flap on the affected side; bilateral nasal leak or fracture across both sides of the paranasal sinus is mostly craniotomized by bilateral frontal or coronal bone flap. ②The dura is carefully separated from the posterior wall of the frontal sinus, orbital apex, pterygoid crest, coronoid and sieve plate area, and fractures and leaks can be found; the dura is often thickened and caught in the bone suture at the site of the leak, which should be separated and removed as close as possible to the skull and avoid expanding the fistula. (3) If the epidural exposure is poor or the fistula is too large and the epidural repair is difficult, the posterior wall of the frontal sinus, sieve plate and saddle, paracranial, and the large wing of the overgassed pterygoid can be explored subdurally in turn.
(4) Intracranial repair method – cerebrospinal fluid ear leak repair ① longitudinal fracture of the rock bone involves the tympanic cap, and cerebrospinal fluid directly enters the middle ear cavity and flows into the external auditory canal through the ruptured periosteum, which is a vagal external ear leak; transverse fracture of the rock bone involves the vagus, so that the subarachnoid cavity communicates with the middle ear cavity is a vagal internal ear leak. ②The temporo-occipital bone flap is often used to repair cranial middle fossa auricular leaks, and the base of the bone flap should be as close as possible to the base of the middle cranial fossa. (③The vagus inner ear leak can also be repaired through the suboccipital approach and behind the rock bone without placing drainage after surgery. If the fistula is located in the posterior cranial fossa, it can be repaired by using the posterior or anterior suboccipital sigmoid sinus approach, the combined upper and lower transmural approach, and the temporal-rock-vagus approach.
(5) Extracranial repair method ①There are three common methods for repairing cerebrospinal fluid leaks through extracranial access: transnasal microscopic repair, long-wing rhinoscopic repair and transnasal endoscopic repair, with the most accurate effect of transnasal endoscopic repair.
(6) Surgical precautions ① Regardless of the material used for fixation, trauma should be created around the leak, scraping away the mucosa and periosteum to expose the bone surface. ②The graft material should be large enough. ③After intracranial and extracranial repair, one should continue to maintain the prone position, head height 30°, use laxatives as appropriate, keep the nasopharyngeal cavity clean, use cranial pressure lowering drugs if necessary, and choose sensitive antibiotics that can easily cross the blood-brain barrier.
(7) Common reasons for failure of intracranial and extracranial repair ① Inaccurate judgment of the location of the leak. (2) Multiple leaks are formed in different parts. (3) Large or deep in the injury site. ④Improper selection of repair material or not big enough. ⑤ Excessive intracranial pressure, which affects graft survival. ⑥Complicated infection, such as septic meningitis or meningoencephalitis. (7) Complicated spontaneous or medically-derived cerebrospinal fluid leak.
(8) Treatment of cerebrospinal fluid wound leaks should be treated immediately upon detection; non-surgical treatment should be given first, while a silicone tube should be placed locally in the repaired surgical field to drain cerebrospinal fluid through a subcutaneous tunnel, or a ventriculocentesis should be performed at the end of the scalp beyond the wound leak, or a contralateral ventriculocentesis should be performed for continuous drainage, or a tube should be placed through a lumbar puncture to drain cerebrospinal fluid, and the drainage flow should be adjusted until the leak stops overflowing.