This site is targeted at medical and radiology professionals, contains user contributed content, and material that may be confusing to a lay audience. Use of this site implies acceptance of our Terms of Use.

Spontaneous intracranial hypotension

Dr MT Niknejad and Dr Frank Gaillard et al.

Spontaneous intracranial hypotension (SIH) most commonly results from CSF leaks in the cervical and thoracic spine 4, and leads to alterations in the equilibrium between the volumes of intracranial blood, CSF, and brain tissue (Monro - Kellie hypothesis). A decrease in CSF volume leads to compensatory dilatation of the vascular spaces, mostly venous side due to its higher compliance.

It is identical to CSF leaks that occur following lumbar puncture, surgery or trauma, connective tissue disorders like Marfan's Syndrome.

Clinical presentation

The condition often presents as a positional headache which is relieved by a recumbent position. It is confirmed by assessing opening pressure on LP (less than 7 cm CSF) 2. Note that when this is done fluoroscopically, it should be performed in lateral position to allow for accurate measurement of pressure.

Occasionally presentation is more sinister, with even decreased level of consciousness and coma reported 3.

Radiographic features

CT Brain

Described features include

  • sub-dural collection
  • cerebellar tonsillar herniation into the foramen magnum (acquired Chiari I malformation)
  • dural venous sinus distention
CT Myelogram

Myelography is useful in identifying the location of CSF leak. Ideally the lumbar puncture is performed on the CT table. 10 mls of myelographic contrast is slowly introduced into the thecal space. Following removal of the needle the patient is asked to roll once and is immediately scanned. It is important to scan early as contrast will track a long way from the leak in a relatively short time.

MRI Brain
  • diffuse brain swelling 3
  • sagging brainstem
  • droopy penis sign : perhaps only an Australianism to denote the shape of the downward drooping splenium of the corpus callosum
  • subdural effusions
  • Increased fluid around optic nerves 
  • Bulbous dilatation of sheath behind globes
  • rounding of the cross-section of the dural venous sinuses (venous distension sign)
  • contrast-enhanced MR imaging demonstrates
    • venous sinus engorgement
    • pachymeningeal enhancement (infra- and supra-tentorial)
    • enlargement of the pituitary gland

Treatment and prognosis

Epidural blood patch ideally at the sight of CSF leak is the treatment of choice.

More content required for prognosis

This article is a stub, which means it needs more content. You can contribute to Radiopaedia.org too. Just register and edit... every little bit helps.

Updating… Please wait.
Loadinganimation

 Details successfully updated.

Error Unable to process the form. Check for errors and try again.

 Thank you for updating your details.