6. IIH Epidemiology:
• 2.2 cases per 100,000 population
• Non-obese pediatric or obese adult
females with menstrual irregularities
• >90% of IIH patients are women of
childbearing age
• Men with IIH are twice as likely to lose
visual function as a result of
papilledema
IIH Diagnosis:
• Visual function tests are the most
important for diagnosis
• Ophthalmoscopy, optic nerve
photography, and sometimes optical
coherence tomography
• Formal visual field assessment
• Ocular motility examination
• Neuroimaging before LP to rule out
possible intracranial lesion and dural sinus
thrombosis
• Combined MRI/MRV + gadolinium=
preferred study
• LP for OP (>25 cm H20), cell count,
cytology, culture, etc…
Editor's Notes
While once called benign intracranial hypertension, to distinguish it from secondary intracranial hypertension produced by a neoplastic malignancy, it is not a benign disorder. Many patients suffer from intractable, disabling headaches, and there is a risk of severe, permanent vision loss.
Pulsatile tinnitus represent vascular pulsations transmitted by CSF under high pressure to the venous sinuses. They sound like pulsating running water or wind
Falsely elevating OP may occur in sitting or prone position
The Monro-Kellie hypothesis states that the cranial compartment is incompressible and that the volume inside the cranium is fixed. The cranium and its constituents (blood, CSF, and brain tissue) create a state of volume equilibrium
Cushing reflex: When the ICP exceeds the MABP, arterioles located in the brain's cerebrum become compressed. In the first stage of the reflex, sympathetic nervous system stimulation is much greater than parasympathetic stimulation.[13] The sympathetic response activates alpha-1 adrenergic receptors, causing constriction of the body's arteries (hypertension + tachycardia as an attempt to restore blood flow to brain). In the second stage, baroreceptors in the aortic arch detect the increase in blood pressure and trigger a parasympathetic response via the Vagus nerve. It is usually seen in the terminal stages of acute head injury and may indicate imminent brain herniation. It can also be seen after the intravenous administration of epinephrine and similar drugs
Bedside ultrasonography has been used to identify intracranial hypertension by precisely measuring the diameter of the optic nerve sheath. [65] If this diameter increases in primary gaze and diminishes by 25% in eccentric gaze (30° test), then increased subarachnoid fluid surrounding the optic nerve is presumably present. This finding is consistent with papilledema if it is bilateral.
The drawback of this noninvasive technique is that it requires a highly skilled clinician to obtain reproducible results.
Indomethacin - Some reports suggest that indomethacin may have efficacy in the treatment of secondary intracranial hypertension (eg, traumatic brain injury, hepatic encephalopathy) presumably by causing cerebral vasoconstriction and reducing cerebral blood flow [53]. In one report of seven patients with IIH, intravenous administration of 50 mg indomethacin was associated with prompt reduction in CSF pressure, and long-term treatment with 75 mg daily produced symptom relief, and improvement in visual fields and papilledema grade
Above: Cranial MRI scan showing intracranial hypertension in an 11 year old male patient with no signs of venous sinus thrombosis in the MRI venography. After neuroimaging procedures, a lumbar puncture was performed revealing an opening pressure of 80 cm H2O with normal CSF composition with no evidence of pleocytosis, elevated protein or low glucose.
*MRI may show findings of ICH including dilated optic nerve sheaths and an empty sella turcica
*Dilated funduscopic exam also helps differentiate true papilledema from pseudopapilledema secondary to optic disc drusen, tilted optic discs, or other mimickers
Optic nerve sheath fenestration (ONSF)
*Acetazolamide may also decrease appetite leading to decreased weight
*Patients with visual loss require urgent treatment with corticosteroids to rapidly decrease ICP, but not for long term. Medically intractable IIH can be treated with surgery (fenestration or shunting). Surgery is primary indicated for visual loss or worsening vision due to papilledema
