Makindo Medical Notes

Related Subjects: |Brain tumour s |Astrocytomas |Brain Metastases |Tuberous sclerosis |Turcot's syndrome |Lhermitte Duclos Disease |Oligodendroglioma |Acute Hydrocephalus |Intracranial Hypertension |Primary CNS Lymphoma (PCNSL)

Visual field loss, classically early loss of the blind spot and inferonasal fields, is common in IIH and may mimic a tumour.

About

• Most common in young, obese females.
• Also called Pseudotumour cerebri, as it mimics a brain tumour.
• May not be benign, as it can cause papilloedema and potential visual loss.

Aetiology

• Unknown cause, but often affects overweight young females.
• Cerebral venous thrombosis should always be considered.

Associations

• Pregnancy, oral contraceptive use, thrombophilia.
• Medications: retinoids, Vitamin A, tetracycline, minocycline.
• Ketamine, nitrous oxide.

Clinical Presentation

• Headache: Worsens when lying down and is most severe upon waking. Often relieved by reducing ICP.
• Visual Symptoms: Blurred vision, enlarged blind spot, transient visual changes, papilloedema, and visual field loss.
• Other Symptoms: Diplopia, tinnitus, neck, and back pain. Some report recent weight gain or new medications.

Investigations

• Blood tests: FBC, U&E, LFT, CRP, ESR, ALP.
• Visual field testing (perimetry): Identifies visual field loss, commonly blind spot enlargement and inferonasal loss.
• Imaging: CT/MRI may show empty sella, optic nerve tortuosity, enlarged optic nerve sheath, and excluded venous thrombosis. CTV to assess venous drainage.
• LP (Lumbar Puncture): Shows high opening pressure (>25 cm H₂O) with normal CSF constituents.

IIH Diagnostic Criteria

Differential Diagnosis

• Venous sinus thrombosis
• Brain tumour
• Hydrocephalus

Management Goals

• Exclude venous thrombosis.
• Protect vision, especially in fulminant cases.
• Reduce intracranial pressure (ICP) and minimise headache morbidity.

Management

• Discontinue causative medications: Avoid Vitamin A, minocycline, isotretinoin, danazol, nitrofurantoin, etc.
• Weight Loss: Effective for those with BMI > 30 kg/m²; bariatric surgery may be required.
• Medications:
  • Carbonic anhydrase inhibitors (e.g., acetazolamide, starting at 500 mg twice daily).
  • Loop diuretics and Topiramate may be considered.
  • Steroids are generally avoided due to rebound intracranial hypertension.
• Surgical Options:
  • Shunting (VPS or LPS) for patients who fail medical therapy.
  • Optic nerve sheath fenestration for rapid papilloedema and visual loss.

References

• Papilloedema: Epidemiology, Etiology, and Clinical Management (2015)
• Idiopathic Intracranial Hypertension: Consensus Guidelines on Management