A cerebrospinal fluid fistula usually results from a tear of the dura mater in the course of cranial trauma or surgery and corresponds to a pathologic connection of the cerebrospinal fluid and nasal or ear spaces. Cerebrospinal fluid leaks from the nose or the ear. Therapy involves microsurgical closure of the CSF leak.
What is a cerebrospinal fluid fistula?
CSF is formed by the choroid plexus and circulates through the central nervous system in a communicating cavity system. The cavity system is called the CSF space. CSF enables the metabolism of neurons in the central nervous system and, in the form of a water cushion, also protects the brain from mechanical impact. The CSF and the CSF space can be affected by changes in the context of various diseases of the central nervous system. For example, if there is a connection between the external world and the CSF system after a traumatic brain injury, this pathological phenomenon is called a CSF fistula. Depending on the type of connection, different types of CSF fistula are distinguished. In addition to otogenic indirect CSF fistula and ontogenic direct CSF fistula, neurologists know, for example, nasal CSF fistula. Direct otogenic CSF fistulas create a connection between the CSF space and the middle ear. Indirect otogenic CSF fistulas create a connection via the ear labyrinth, and nasal ones create a connection via the nasal cavity.
Causes
The causes of a cerebrospinal fluid fistula can be found in traumatic skull injuries. In most cases, the connection is due to a tear of the dura mater, often resulting from a skull base fracture. Skull base fractures are often the result from accidents or are caused by hard blows. Other traumatic injuries to the skull are also conceivable causes of CSF fistula. For example, the dura mater need not be torn in all cases. In addition to accidents and traumatic injuries, surgery to the skull is also a possible cause of a cerebrospinal fluid fistula. For example, the pathologic connection of the CSF spaces to the outside world is a possible postoperative complication in the course of some cranial operations.
Symptoms, complaints, and signs
Patients with a cerebrospinal fluid fistula usually do not experience pain. They notice the connection between the CSF space and the external space in most cases by a cerebrospinal fluid (CSF) murmur. This symptom is considered the leading symptom of CSF fistula and refers to the flow of cerebrospinal fluid from the nose or ear. Thus, CSF leaks out of the CSF space through the resulting connection. When liqour leaks through the ear, it is referred to as otoliquorrhea. On the other hand, if the cerebrospinal fluid leaks through a connection between the nasal and CSF spaces, the doctor refers to it as rhinoliquorrhea. If there is a connection to the ear space, the CSF can also enter the tympanum, causing symptoms such as hearing loss. CSForrhea secondary to traumatic brain injury usually occurs in the first three days after the trauma. The CSF discharge then usually corresponds to a light drip from the nose or watery, drop-like discharge from the ear canal. The amount of discharge is usually small, in the range of a few milliliters. Depending on the cause of the CSF fistula, patients may suffer from other symptoms, such as pain in the case of a skull fracture. In some cases, the discharge resolves within a week.
Diagnosis and course of the disease
Since CSF fistulas are symptomatically manifested mostly by CSF rheumatism, the physician first clarifies the causes of the CSF flow. To do this, he must clarify whether the discharge is CSF at all. This clarification corresponds to a determination of Βeta-2-transferrin or beta-trace protein. Determination via glucose test strips is also conceivable. This diagnostic step is followed by localization of the CSF source. Imaging such as CT and MRI are used for this purpose. The suspicion of a CSF fistula is confirmed at the latest with the imaging procedures. Intrathecally, sodium fluorescein is usually injected, which becomes visible in the course of the fistula and at its exit. The prognosis for patients with a cerebrospinal fluid fistula is favorable.
Treatment and therapy
Treatment of a cerebrospinal fluid fistula is usually causal. The leak in the CSF space must be closed for this purpose. Intervention is not indicated in all cases. Some CSF fistulas close on their own, especially otogenic CSF fistulas.Therefore, in such cases, observation of the patient may initially make sense, possibly sparing the affected person an invasive procedure. The situation is different with rhinogenic CSF fistulas. Invasive treatment to close the leak is indicated in virtually all cases with connections to the nasal cavity. CSF fistulas at this site usually do not close on their own and therefore require prompt intervention. Thus, an observation period makes little sense for nasal CSF fistulas. In most cases, surgical closure is performed immediately after diagnosis. The treatment of choice is usually microsurgical closure of the fistula. Prior to the procedure, the patient is injected intrathecally with a dye so that the physician can clearly trace the course and exit of the fistula during the procedure and seal the connection to the nasal cavity with pinpoint accuracy. In young children, anesthesia may be useful before the microsurgical procedure. On adults, anesthesia is not required in most cases.
Outlook and prognosis
Under optimal conditions, relief of symptoms from a cerebrospinal fluid fistula occurs within one week. Frequently, fistulas close on their own as they progress. Nevertheless, the development must be closely monitored by physicians. Since it is a complication of an operation as well as a consequence of a skull injury, the affected person is usually already undergoing medical treatment. If the symptoms increase or the irregularities persist over a longer period of time, a new operation is performed. Developments are assessed according to individual circumstances. Nevertheless, most patients are given a good prognosis. Since it is usually sufficient to observe the self-healing process of the organism, no long-term complications or secondary disorders are to be expected as a rule. In exceptional cases, closure is performed, which is handled as a routine procedure. Should any complications occur, the surrounding tissue areas may be injured, resulting in permanent functional disorders. In addition, there is a possibility that the affected person may develop sepsis. Sepsis is a potentially life-threatening development and may result in the premature death of the patient. Therefore, further health developments should be monitored and negative changes should be discussed immediately with the physician.
Prevention
CSF fistulas can be prevented in moderation. However, because nothing can prevent accidents involving skull base fractures with absolute certainty, there is always a residual risk of CSF fistulas. During surgery, physicians can prevent cerebrospinal fluid fistula by proceeding with caution in the area of the dura mater.
Follow-up care
Even during the treatment of a cerebrospinal fluid fistula, regular visits to the doctor must not be missed. Otherwise, serious complications may arise that cannot be recovered afterwards. Appropriate aftercare is also very important and significant in this case. Possible complications can be detected, treated and eliminated at an early stage. Even in the case that the CSF fistula could be treated successfully, further visits to the doctor are necessary. Through appropriate follow-up care, later brain damage can be diagnosed at an early stage so that late consequences can be avoided. Even several years later, preventive examinations should always be performed. Appropriate and regular aftercare is just as important as the treatment itself. This is the only way to detect and treat late sequelae or other diseases that can be traced back to the development of a cerebrospinal fluid fistula. A complete and lasting recovery is therefore very much dependent on proper aftercare.
