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A 24-year-old woman with rapidly progressing vision loss
Digital Journal of Ophthalmology 2017
Volume 23, Number 1
January 15, 2017
DOI: 10.5693/djo.03.2016.10.001
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Milad Modabber, MD, MSc | Department of Ophthalmology, McGill University, Montreal, Quebec, Canada Vasudha Gupta MD, FRCSC | Department of Ophthalmology, Queen’s University, Kingston, Ontario, Canada Amadeo R. Rodriguez, MD | Department of Surgery Ophthalmology and Medicine Neurology, McMaster University, Hamilton, Ontario, Canada
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| Diagnosis and Discussion | The elevated ICP without any clinical, laboratory, or radiographically identifiable etiology led to the diagnosis of IIH. The severity of visual loss and the rapidly progressive nature of this case reflected the fulminant form of IIH, prompting urgent diagnosis and management.
The overall incidence of IIH is 1-3 per 100,000, but it rises dramatically to 20 per 100,000 among female patients who are obese or have experienced recent weight change.(1,2) Fulminant IIH is a particularly acute and rapidly progressive form of IIH, with an incidence of 2.2% to 2.9% of all new IIH cases.(3)
Normally, vision loss in IIH is secondary to chronic papilledema;(4) however, progressive vision loss is rare and may indicate secondary causes of increased ICP, such as a meningeal process or venous sinus thrombosis.(5,6) Fulminant IIH is an acutely severe and rapidly progressive form of IIH, with resultant permanent visual sequelae.(3,7-13) It is defined as acute onset of signs and symptoms of intracranial hypertension; (<4 weeks between onset of initial symptoms and severe visual loss), rapid worsening of vision loss over several days, and a normal MRI and MRV (or CT venogram).(3) There is limited literature on fulminant IIH.(8-12)
The pathophysiology of IIH remains unknown. Vision loss in papilledema is thought to be secondary to elevated CSF pressure transmitted to the anterior optic nerve sheath, resulting in axoplasmic flow stasis and subsequent intraneuronal ischemia.(14) It is unclear why the condition manifests more rapidly and severely in some patients. The clinical characteristics of fulminant IIH are similar to those in the nonacute form.(3)
The treatment of fulminant IIH aims to alleviate symptoms and to preserve visual function. Fulminant IIH requires surgical intervention. Close observation and temporizing measures, such as repeat lumbar punctures, lumbar drain placement, acetazolamide and intravenous steroids are indicated prior to surgery.(3) The patient in our case was treated with 1 g daily acetazolamide, because she was unable to tolerate a higher dose. Although patients can be treated with up to 4 g daily of acetazolamide, few patients can actually tolerate the side effect profile.
The use of corticosteroid therapy in the context of IIH has been suggested to decrease CSF formation at high ICP, to increase CSF absorption, and to mitigate papilledema independent of any change in ICP.(15) Nevertheless, long-term use of steroids is not recommended due to well-established side effects.
Surgical management consists of CSF diversion procedures, namely, lumboperitoneal shunts and ventriculoperitoneal shunts, as well as optic nerve sheath fenestration (ONSF). In the United States, from 1988 to 2002, the frequency of CSF shunting procedures (lumboperitoneal and ventriculoperitoneal) for the treatment of IIH increased by 350%.(16) Recently, venous sinus stenting has been performed on selected patients with IIH, although this remains an area of debate.(17) To our knowledge, there have been no randomized, prospective trials undertaken to date that compare the efficacy and visual outcomes of these procedures in treating IIH.(18) In addressing the underlying etiology of increased ICP, CSF diversion techniques improve papilledema and reduce further visual loss; however, they do not restore visual loss.
ONSF has also been shown to prevent visual deterioration and even improve visual function in some patients with IIH.(19) However, up to one-third of patients with initially improved symptoms following ONSF experience worsening of visual acuity and visual fields over time. Thus, these patients require long-term follow-up, as deterioration of visual function may necessitate repeat procedures for ONSF failures. Overall, the decision to perform CSF diversion procedures or ONSF often depends on local availability and expertise as well as the predominance of the presenting symptoms. CSF shunting is often undertaken when headache is the primary presentation, whereas ONSF is carried out when vision loss is predominant.(20,21)
Regardless of the choice of procedure, there is consensus for rapid and definitive treatment in rapidly progressive and refractory cases of IIH, as delay in surgical intervention can lead to worse visual outcomes.(3,21) Thambisetty et al conducted the largest reported case series of fulminant IIH in 16 patients, who underwent surgical CSF shunting procedure or ONSF.(3) Visual function improved in 14 of 16 patients postoperatively, although 8 patients (50%) remained legally blind at last follow-up; visual fields remained severely altered in all cases. Notably, the 8 patients who remained legally blind had a median delay in surgical intervention of 6.5 days from the time of diagnosis (range, 3-37 days), whereas those that regained significant visual function had a median delay of only 2 days (range, several hours to 4 days), highlighting the importance of prompt and aggressive management.
Altogether, the acute progression and long-term visual sequelae of fulminant IIH in otherwise young healthy patients merits appropriate recognition, emergent neuro-ophthalmic evaluation, and possible surgical intervention. Surgical management is recommended in medically refractory cases with established progressive visual loss. | |
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