The story has made the rounds of social media: a woman had a terrible runny nose that never stopped. Assuming it was allergies, she endured this situation for years before finally discovering that she was leaking cerebrospinal fluid (CSF) into her nose through a small hole in her skull. The hole resulted from head trauma she had received in a car accident some time prior.
Biomedical scholar H.C. Jones writes in Science Progress that the existence of cavities in the brain has been known since ancient Greece, and by the eighteenth century (if not earlier), it became known that these spaces contained a clear liquid. The brain and the spinal column are surrounded by a tough membrane called the dura, which helps protect these vital structures from trauma, but the space surrounding the brain and the spinal column is also filled with CSF.
The CSF is secreted deep in the brain by the telencephalic choroid plexuses, and passes into the vacuoles through a convoluted pathway. CSF helps cushion the brain and spinal column from impact. The CSF (and the brain) are partially insulated from the broader circulatory system by capillary barriers, and these systems help control what substances may enter the brain, helping the CSF maintain very particular chemical conditions. Finally, CSF has an execretory function as well: in most of the body the lymphatic system helps drain unwanted substances, but the brain and spinal column do not have lymph nodes; the CSF takes over some of the job of removing unwanted waste from the nervous system.
Despite all the body’s physical precautions, as physician A.M. Nussey points out, head injuries can fairly easily lead to CSF escaping through the nose. From there, it can end up in the lungs, potentially causing pneumonia. Some of these cases have been associated with meningitis, or infection of the membranes surrounding the brain. Alternatively, according to neurosurgeon Campbell Connolly, the leakage of CSF through the nose (or ears) reduces pressure in the intracranial space, allowing large, dangerous bruises to form. Thanks to the CSF leak, the bruises present very few symptoms and the dangerous condition is difficult to diagnose.
The patient in the recent case was convinced that something serious was wrong, and had to persist until she finally found the truth. These bizarre injuries are uncommon, but as noted by Nussey, perhaps more common than you might think.