What Causes Cerebrospinal Fluid Rhinorrhoea?

Cerebrospinal fluid rhinorrhoea occurs when the cerebrospinal fluid, or CSF, that bathes the brain leaks through surrounding membranes and bone and emerges through the nose. Anything which causes a tear in the dura and arachnoid mater, the membranes that enclose the brain and CSF, and also makes a hole in the skull, could lead to the formation of a drainage channel between the brain and nose. The most common cause is a head injury, as the result of an accident or acquired during surgery. Tumors and birth defects may also lead to drainage of cerebrospinal fluid through the nose, or it may occur without any obvious reason. Rhinorrhoea is a British spelling, and in the United States, the word is more typically spelled rhinorrhea.

A patient with cerebrospinal fluid rhinorrhoea may be unaware of the condition, or may experience symptoms of a clear, typically unilateral nasal discharge, which is watery and may taste salty. In around 90 percent of cases, the problem is caused by an injury to the head. Broadly speaking, cerebrospinal fluid rhinorrhoea may be divided into two main categories with different causes, known as traumatic and atraumatic. Traumatic cases are those which have resulted from an injury, and atraumatic are due to other causes.

The traumatic causes of cerebrospinal fluid rhinorrhoea can be divided further into those which occur as a result of surgical procedures and those which are due to accidental injury. Accidental injury is more common and could consist of a blow to the head with a blunt object or what is known as a penetrating injury, where something pierces the skull. Sometimes a CSF leak is noticed immediately, inside the first 48 hours, and at other times there may be a delay of up to three months before the condition becomes apparent. Non-surgical injuries, such as motor vehicle accidents, are more likely to lead to an immediate CSF leak, while a leak following surgery might take longer to develop. The types of surgery which are typically associated with cerebrospinal fluid rhinorrhoea are neurosurgical procedures and sinus operations.

Atraumatic causes of cerebrospinal fluid rhinorrhoea include birth defects, in which the skull and the membranes surrounding the brain fail to form properly. Aggressive tumors may grow through the bone of the skull and disrupt the dura mater membrane, allowing CSF to leak from the subarachnoid space around the brain. Sometimes cerebrospinal fluid rhinorrhoea seems to arise spontaneously, but this is usually the result of raised pressure inside the skull. This raised pressure eventually weakens the bone and causes a hole, allowing membranes, and sometimes brain tissue, to herniate through.

Cerebrospinal fluid rhinorrhoea is associated with a serious risk of brain infection, or meningitis, which can be fatal. Some cases may be treated with a combination of bed rest and medication. Others require surgery to repair underlying defects.