IIH (Pseudotumor Cerebri)

FACTS

  • Definition: elevated intracranial pressure w/o evidence of any mass, infection, hydrocephalus
  • Demographics: obese females of child-bearing age
  • This is a diagnosis of exclusion
  • pathogenesis:
    • obesity --> pressure --> ↑ CVP --> ↓ CSF resorption
    • fat cells convert androstenedione --> estrone --> ↑ CSF production

HPI

  • BMI
ROS
  • HA
  • neck pain
  • blurry vision
  • parasthesias
  • double vision - horizontal or vertical?
  • enlarged dark spot in temporal field?
  • Pulsatile tinnitus? ("whooshing sound")
  • Transient obscurations of vision (TOVs)? these usually last seconds
  • Nausea/vomiting?
  • Lethargy/somnolence?
  • Drugs
    • tetracyclines (reduce CSF absorption at the arachnoid villi)
    • Accutane
    • Bactrim
    • Tamoxifen
    • Cimetidine
  • Comorbidities:
    • SLE

PHYSICAL EXAM

  • Optho exam: fields and acuity
  • Diplopia w/ abduction or at baseline?
  • CN 6 palsy
  • Tinnitus
  • Ataxia
  • VF/VA

IMAGING

  • CT venogram for dural sinus thrombosis
  • MRI/MRV with CISS sequences (rule out co-occurring Chiari)
    • slit-like ventricles
    • empty sella
    • brain should otherwise be negative (by definition)
    • Orbital findings:
      • flattening of posterior sclera
      • enhancement of optic nerve
      • tortuosity of orbital optic nerve
A/P
Diagnosis:
  • LP w/ OP > 25 and normal CSF
  • Optho c/s for optic atrophy, papilledema evaluation
Management
  • Serial LPs
  • weight loss
  • Medical management:
    • diamox
    • Lasix
  • Operative options
    • optic nerve sheath fenestration
    • shunts
    • Transverse sinus stenting
    • subtemporal decompression

Radiographic findings - expanded

Sinus stenosis

FSPGR sequences demonstrating bilateral transverse sinus stenosis before (LEFT) and after (RIGHT) VP shunting
FSPGR sequences demonstrating bilateral transverse sinus stenosis before (LEFT) and after (RIGHT) VP shunting

Empty sella

notion image
Sagittal FLAIR sequences demonstrating partially empty sella (LEFT) with significant improvement (RIGHT) after VPS shunting. Physiology of empty sella: high pressure gives way to CSF entering the suprasellar cistern, flattening the pituitary to the floor of the sella.