Spontaneous Intracranial Hypotension

Synonyms:

a.k.a. sinking brain syndrome a.k.a. Spontaneous CSF leak

Diagnosis:

Clinical:

  • Orthostatic headache a.k.a. postural headache (improves on lying down):
  • Worsened by standing in <15 minutes
  • Associated symptoms: tinnitus, hypacusia, photophobia, nausea, neck stiffness
  • May present with thunderclap headache
  • Later stages: drowsiness, coma
  • No history of dural puncture or LP

MRI:

  • Postcontrast: enhancement of thickened dura i.e. Pachymeningeal enhancement.
  • Brain sagging (effacement of the suprasellar cistern, bowing of the optic chiasm over the pituitary fossa, flattening of the pons against the clivus and obliteration of the prepontine cistern) & pseudo-Chiari malformation (hindbrain herniation)
  • Dilation of veins & venous sinuses. Subdural fluid collections.
  • Also enlarged pituitary gland, dilation of the spinal peridural plexus

If with nasal discharge:

  • Test for Beta 2 Transferrin by immunofixation, present in CSF

Lumbar Puncture, LP:

  • Low opening pressure (<6 cmH2O) or dry tap
  • Protein: usually high,
  • Pleocytosis: occurs
  • Xanthochromia may occur

CT myelography:

  • Study of choice for defining the leak
  • Myelography with water-soluble contrast followed by CT scan

Radionuclide cisternography:

  • 111 Indium-diethylenetriamine pentaacetic acid
  • Not as sensitive as CT myelography

Meningeal biopsy:

  • A thin layer of fibroblasts in the subdural zone
  • Small thin-walled dilated blood vessels
  • No evidence of inflammation
  • Meningeal fibrosis in longstanding cases

Treatment:

Epidural blood patch 20mL. [312] This may be repeated 20-100mL.

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