Pediatric Idiopathic Intracranial Hypertension

• Etiology:
  — Cerebral or extracranial venous abnormalities
  — Increased abdominal and thoracic pressure much more than poor cerebral venous return
  — Disturbance of cerebrospinal fluid homeostasis: decreased absorption perhaps due to microthrombi
  — Alteration in Vitamin A metabolism or excess cerebrospinal fluid retinol interferes with cerebrospinal fluid
  — Human growth hormone: Aquaporin 4 levels in cerebrospinal fluid reduced
  — Adipose tissue as an actively secreting endocrine tissue (e.g. leptin)
  — Sleep apnea induced elevation of intracranial pressure
  — Secondary causes of intracranial hypertension are mass lesion, venous obstruction from thrombosis or meningioma, AV fistula
• Imaging:
  — Flattening of posterior pole of eyes and bulging of optic disc
  — Dilation and tortuosity of optic nerve sheaths
  — Empty sella turcica
  — Stenosis of one or both transverse sinuses
  — Enlarged extraventricular cerebrospinal fluid spaces
  — Low position of cerebellar tonsils
  — Enlargement of superior ophthalmic vein
• Note:
  — Younger children less frequently show MRI findings of idiopathic intracranial hypertension, particularly cerebellar tonsillar herniation and transverse sinus stenosis
  — Findings of cerebrospinal fluid pressure abnormality are dynamic and may vary over time
  — Secondary cerebellar tonsillar herniation may occur with high and low cerebrospinal fluid pressures so whenever faced with low cerebellar tonsils beware of acquired tonsillar herniation mimicking Chiari I and carefully inspect posterior fossa and dural venous sinuses and orbits and pituitary gland
• DDX:
• Complications: Debilitating headaches, pulsatile tinnitus, visual loss
• Treatment: Weight loss, Diamox, lumbar puncture or shunt, optic nerve fenestration, transverse sinus stenting
• Clinical:
  — Is a diagnosis of exclusion
  — Papilledema
  — Classic presentation is obese women age 20-44 with headaches and with or without vision loss and increased intracranial pressure
  — Chronically elevated increased intracranial pressure is most likely a consequence of a prolonged increased extracranial resistance to venous outflow

Radiology Cases of Idiopathic Intracranial Hypertension