Cerebrospinal fluid leak

Cerebrospinal fluid leakage can occur at numerous sites and may be clinically occult, or result in various clinical presentations depending on the site and rate of leakage.

Epidemiology

The epidemiology of individuals with CSF leak will vary greatly according to the wide range of etiologies, which include:

• trauma (e.g. base of skull fractures, penetrating injury)

• iatrogenic (e.g. lumbar puncture, surgery involving the dura)

• tumors and infections or the skull or spine

• congenital (e.g. some neural tube defects)

• idiopathic/spontaneous (e.g. ventral dural defects, CSF-venous fistulas)

Clinical presentation

Clinical presentation will depend on cause and location and may either be direct evidence of the leaks or signs and symptoms related to the leak or its downstream effects.

Direct visualization of leaking CSF includes:

• CSF rhinorrhea

• CSF otorrhea

• meningoceles may leak directly though a skin defect (e.g. myeloschisis) or internally ³

• pseudomeningoceles may leak through surgical/trumatic wounds

• spinal meningeal cysts leaking into body spaces (e.g. pleura ⁴)

Consequences of reduced CSF volume or CSF leakage include:

• intracranial hypotension

• slit ventricle syndrome

• superficial siderosis, particularly secondary to dural defects and CSF-venous fistulas ⁵

A common misconception is that all CSF leaks present with intracranial hypotension. This has been shown to not be the case and CSF leak from the base of skull rarely, if ever, presents with signs and symptoms of intracranial hypotension ^1,2.

Radiographic features

The features, if any, will depend on the underlying cause as well as the location and rate of leakage. CSF may be visulised directly as fluid or the sequaela of CSF hypovolemia or chronic leakage may be seen. These are discussed separately according to etiology.