A cerebrospinal, or CSF, leak occurs when there is a tear in the membrane containing the CSF. This allows the fluid to leak out through either the ears, nose or from a head or spinal wound. When the fluid drains, it diminishes the cushioning power which causes the brain to rest directly on the skull, causing headaches.
There are a handful of causes of a CSF leak. These include trauma to the head or spine, surgery, placement of epidural anaesthesia tubes, a spinal tap, tumours and conditions that increase pressure in the brain, like hydrocephalus.
A CSF leak can happen whenever there is head or spine trauma. Such trauma can include an epidural hematoma (a blood clot develops between the skull and dura), a subdural hematoma (blood clot between the dura and brain), a skull fracture, a concussion, a spinal cord injury, a spinal fracture and a traumatic nerve injury. Another result of a head trauma is an intraparenchymal haemorrhage, which, according to Stanford School of Medicine, is "a blood clot that develops within the brain substance." Trauma, such as an intraparenchymal haemorrhage, can sometimes occur after the trauma and appear as a blood clot or bruise on the brain.
Sometimes, during the placement of an epidural, CSF fluid can leak. This will inevitably cause a headache, which can be resolved with hydration or pain medication. An epidural is commonly used for pain relief during childbirth or even for post-surgery pain relief. The epidural is injected into a part of the spine called the epidural space (the space surrounding the spinal cord). The anaesthesiologist inserts a catheter through the skin in the back until it enters the epidural space. Receiving an epidural can also cause other potential side effects, other than a headache, including nausea, urinary retention and itching.
A CSF leak can also occur when there is an increased pressure in the brain, as in the condition called hydrocephalus. Hydrocephalus is a build-up of excessive fluid in the brain. Formally known as "water on the brain," the fluid is actually CSF that accumulates when the normal flow or absorption is blocked. Symptoms include headache, vomiting, nausea, blurred or double vision, sunsetting of the eyes, problems with balance, poor coordination, gait disturbance, urinary incontinence, lethargy, drowsiness, irritability, other personality changes or dementia. Causes include inherited genetic abnormalities or developmental disorders, complications from premature birth, or diseases such as meningitis, tumours or traumatic head injury