Fulminant Idiopathic Intracranial Hypertension

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Increased intracranial pressure of unknown cause is called Idiopathic Intracranial Hypertension (IIH)[1]. Fulminant IIH (FIH) is a subtype of IIH that occurs in 2-3% of patients with IIH and results in severe, rapidly progressive vision loss within one month of IIH symptom onset[2]. These patients are at a high risk for permanent vision loss and require prompt medical diagnosis and treatment[2][3].

Disease

Epidemiology and Risk Factors

Like patients who present with non-fulminant IIH, the majority of patients with FIH are overweight or obese women of childbearing age[4], but FIH has also been reported in atypical populations including children and men[5][6]. It is believed that FIH occurs in 2-3% of patients with IIH[2].

Pathophysiology

The pathophysiology of IIH and FIH have not been fully elucidated, but several hypotheses have been suggested[7][8]. However, the pathophysiology behind the development of FIH and whether it differs from non-fulminant IIH remains controversial.

Diagnosis

Clinical Presentation

FIH presents with acute onset of rapid worsening of vision over days after development of symptoms of increased intracranial pressure[3]. Similar to typical IIH, patients with FIH present with classical features of increased intracranial pressure including headache, pulsatile tinnitus, and transient visual obscurations[2][8][9][10][11].

Diagnosis

The diagnostic criteria for FIH are[2][3]

1. Diagnostic criteria for IIH fulfilled (but including papilledema)

2. Less than 4 weeks between symptom onset and severe loss of visual acuity or field

3. Rapid worsening of vision over days

The diagnosis of IIH is made by the modified Dandy criteria consisting of: (1) signs and symptoms of increased intracranial hypertension, (2) normal neurological exam (except 6th nerve palsy and papilledema) including mental status examination, (3) no evidence of hydrocephalus, mass, structural, or vascular lesion on neuroimaging, (4) increased lumbar puncture opening pressure (>25 cm H2O), (5) Normal cerebral spinal fluid (CSF) contents, and (6) no other cause of increased ICP identified[12].

Diagnostic Procedures

A complete ocular examination including a dilated fundus examination, visual field examination, and optic nerve photographs should be performed[7]. Neuroimaging, specifically magnetic resonance imaging (MRI) of the brain and orbits with and without contrast as well as magnetic resonance venography (MRV) of the brain, are the recommended imaging modalities. Signs of increased intracranial pressure on MRI and MRV include flattening of the posterior globe, empty/partially empty sella, post gadolinium enhancement of the optic nerve, distention of perioptic space, vertical tortuosity of the orbital optic nerve, and stenosis of the cerebral venous sinuses[12].

A diagnostic lumbar puncture should then be performed for patients with suspected IIH. The diagnosis of IIH by the modified Dandy criteria requires an elevated opening pressure greater than 25 cm H2O; however, opening pressures between 20 to 25 cm H2O may still be diagnostic with the presence of one of the following: pulse synchronous tinnitus, abducens palsy, Frisen grade II papilledema, absence of optic disc drusen on ultrasonography, transverse venous sinus stenosis/collapse, or partially empty sella or enlarged optic nerve sheath on neuroimaging[12].

Differential Diagnosis

The differential diagnosis for FIH is the same as IIH but the time course is more rapid and the severity is worse.

Management

General Treatment

The management of FIH differs from typical IIH because of the increased risk of permanent vision loss[3]. In most patients with typical IIH, initial treatments consist of weight loss and medical management, with surgical intervention being utilized in patients with intolerant or refractory IIH[4]. However, for patients with FIH, hospital admission for more rapid confirmation of increased intracranial pressure, a lumbar drain, and aggressive medical and surgical management may be indicated[2][3].

Patients can be started on temporizing medical management of high-dose carbonic anhydrase inhibitors while awaiting surgical management[3]. Intravenous methylprednisolone can also be considered as a temporizing measure[3][4]. If there is an expected delay in surgical intervention (>24 hours) or the visual loss has been particularly rapid, temporizing CSF drainage (e.g., lumbar drain, extraventricular drain, or serial large volume lumbar punctures) may be considered until a permanent surgical intervention can be performed[3].

Medical Therapy

High dose acetazolamide (2-4g per day) is the first line medical treatment while patients are awaiting surgical intervention. Acetazolamide, a carbonic anhydrase inhibitor, is believed to reduce the rate of CSF production. If acetazolamide cannot be used, topiramate or furosemide are sometimes used acetazolamide is the only drug that has been proven effective in controlled clinical manner[13]. Steroids, although not recommended for the treatment of typical IIH, are a treatment option that can be used as a temporizing measure in the form of intravenous methylprednisolone.

Surgical Management

Permanent surgical intervention including CSF diversion procedures, optic nerve sheath fenestration, or venous sinus stenting (VSS) are surgical options for the treatment of FIH. The choice between the three procedures can be based upon the presentation of other symptoms of intracranial hypertension, presence of venous sinus stenosis permitting VSS, and institutional availability and familiarity[3].

CSF diversion procedures includes ventriculoperitoneal shunting (VPS) and lumboperitoneal shunting (LPS) to lower intracranial pressure. Shunting procedures are often favored if headache is prominent[14]. The immediate success rates between VPS and LPS are comparable[15].

Optic nerve sheath fenestration (ONSF) is often chosen if papilledema and vision loss are severe or the primary driver for treatment[16]. ONSF is generally effective with stabilization or improvement of visual acuity[14]. However, headache is less likely to improve following ONSF when compared to other surgical procedures[14].

Venous sinus stenting may be considered if venous sinus stenosis is present. This procedure results in rapid normalization of intracranial pressure with improvement of both visual function and increased intracranial pressure symptoms[17][18].

Prognosis

Rapid diagnosis and management of FIH is necessary to prevent permanent vision loss. Studies have shown that surgical interventions may need to be performed within days of diagnosis as the chance of meaningful visual recovery decreases quickly over time.

Summary

FIH is a subtype of IIH that presents with acute, rapidly progressing loss of vision in the setting of increased intracranial pressure. Prompt treatment is required to prevent permanent vision loss and includes temporizing medical measures until surgical intervention can be performed. Medical management includes high dose acetazolamide, topiramate, or steroids and surgical intervention consists of CSF diversion procedures, optic nerve sheath fenestration, or venous sinus stenting. Surgical intervention should not be delayed as the chance of visual recovery decreases quickly over time.

References

  1. Friedman, D. I. & Jacobson, D. M. Idiopathic intracranial hypertension. J Neuro-Ophthalmol 24, 138–145 (2004)
  2. 2.0 2.1 2.2 2.3 2.4 2.5 Thambisetty, M., Lavin, P. J., Newman, N. J. & Biousse, V. Fulminant idiopathic intracranial hypertension. Neurology 68, 229–232 (2007)
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 Bouffard, M. A. Fulminant Idiopathic Intracranial Hypertension. Curr. Neurol. Neurosci. Rep. 20, 1–9 (2020)
  4. 4.0 4.1 4.2 Ko, M. W. Idiopathic intracranial hypertension. Curr. Treat. Options Neurol. 13, 101–108 (2011)
  5. Jiramongkolchai, K. et al. Temporary Lumbar Drain as Treatment for Pediatric Fulminant Idiopathic Intracranial Hypertension. J. Neuro-Ophthalmology 37, 126–132 (2017)
  6. Pollock, S. C. Acute Papilledema and Visual Loss in a Patient with Pseudotumor Cerebri. Arch Ophthalmol 105, 752–753 (1987)
  7. 7.0 7.1 Mollan, S. P. et al. Evolving evidence in adult idiopathic intracranial hypertension: Pathophysiology and management. J. Neurol. Neurosurg. Psychiatry 87, 982–992 (2016)
  8. 8.0 8.1 Mollan, S. P., Grech, O., Alimajstorovic, Z., Wakerley, B. R. & Sinclair, A. J. New horizons for idiopathic intracranial hypertension: advances and challenges. Br. Med. Bull. 136, 118–126 (2020)
  9. Mollan, S. P., Grech, O., Alimajstorovic, Z., Wakerley, B. R. & Sinclair, A. J. New horizons for idiopathic intracranial hypertension: advances and challenges. Br. Med. Bull. 136, 118–126 (2020)
  10. Kidron, D. & Pomeranz, S. Malignant pseudotumor cerebri. J. Neurosurg. 71, 443–445 (2009)
  11. Mulroy, E., Krishnan, T., Best, S. & Anderson, N. E. Forgetting the fundoscope – A case of fulminant idiopathic intracranial hypertension causing rapid visual loss. J. Clin. Neurosci. 50, 108–110 (2018)
  12. 12.0 12.1 12.2 Friedman, D. I. & Jacobson, D. M. Diagnostic criteria for idiopathic intracranial hypertension. Neurology 59, 1492–1495 (2002)
  13. Çelebisoy, N., Gökçay, F., Şirin, H. & Akyürekli, Ö. Treatment of idiopathic intracranial hypertension: Topiramate vs acetazolamide, an open-label study. Acta Neurol. Scand. 116, 322–327 (2007)
  14. 14.0 14.1 14.2 Satti, S. R., Leishangthem, L. & Chaudry, M. I. Meta-analysis of csf diversion procedures and dural venous sinus stenting in the setting of medically refractory idiopathic intracranial hypertension. Am. J. Neuroradiol. 36, 1899–1904 (2015)
  15. Abubaker, K. et al. Idiopathic intracranial hypertension: Lumboperitoneal shunts versus ventriculoperitoneal shunts - Case series and literature review. Br. J. Neurosurg. 25, 94–99 (2011)
  16. Anderson, R. L. et al. Treatment of pseudotumor cerebri by primary and secondary optic nerve sheath decompression [13]. Am. J. Ophthalmol. 113, 599–600 (1992)
  17. Dinkin, M. J. & Patsalides, A. Venous Sinus Stenting in Idiopathic Intracranial Hypertension: Results of a Prospective Trial. J. Neuro-Ophthalmology 37, 113–121 (2017)
  18. Elder, B. D. et al. Venous sinus stenting is a valuable treatment for fulminant idiopathic intracranial hypertension. J. Clin. Neurosci. 22, 685–689 (2015)
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