Rapidly progressive vision loss due to fulminant idiopathic intracranial hypertension: a diagnostic and management dilemma

Background

Idiopathic intracranial hypertension (IIH) is a syndrome characterised by symptoms of elevated intracranial pressure (ICP) such as headache, transient visual obscurations, tinnitus and diplopia in the absence of any intracranial structural lesions such as intracranial tumour, hydrocephalus, intracranial infections, meningitis and cerebral abscesses.1 2 It commonly affects middle-aged obese women of childbearing age, has an insidious or subacute presentation and vision is preserved until late in the course.3 4 Uncommonly, patients with IIH might have a rapidly worsening course such as acute deterioration of visual function, and other signs of elevated ICP might be less marked. This uncommon form is known as ‘fulminant or malignant IIH’; and if not timely diagnosed or managed, it can lead to permanent loss of vision.5 6 Urgent medical management with high doses of oral acetazolamide followed by early optic nerve sheath fenestration and/or cerebrospinal fluid (CSF) diversion procedures is necessary in preserving visual function in these patients. Furthermore, rapid worsening of visual function might be confused with other pathologies such as optic neuritis, ischaemic optic neuropathy and malignant hypertension. This report highlights a similar case that caused initial diagnostic challenge, but correct interpretation of neuroimaging findings and timely interventions led to preservation of the visual function.

Case presentation

A 44-year-old obese woman presented to our clinic with sudden-onset diminution of vision in her right eye (RE) for 3 days. Vision loss was profound and was associated with diffuse (holocranial) headache that aggravated on bending forward. There was no eye pain or pain on eye movements, photophobia, redness, vomiting, double vision or ptosis. Ocular examination showed a distance best-corrected visual acuity (BCVA) of counting fingers at 1 m in the RE and 20/20 in the left eye (LE). She could only identify demonstration plate in the RE and 5/17 correct plates by Ishihara colour vision testing in the LE. There was grade II relative afferent pupillary defect (RAPD) in the RE, and ocular motility was full in both eyes (BE). Rest of the anterior segment examination was normal in BE.

Fundus examination showed medium-sized optic disc with blurred margins in BE (RE worse than LE), obscuration of the peripapillary retinal nerve fiber layer (RNFL), dilated tortuous veins over the disc and few circumferential folds around the right disc (figure 1A). Formal visual field testing was not possible in the RE, and automated perimetry performed using 24-2 Swedish Interactive Testing Algorithm-Fast strategy in the LE showed central scotoma extending nasally into it (figure 1B). Her blood pressure was 130/80 mm Hg. Her height was 146 cm and her weight was 79 kg, giving a body mass index (BMI) of 37 kg/m^{2 _.}

Figure 1

(A) Fundus photographs of both eyes show 360° disc oedema with blurring of peripapillary retinal nerve fibre layer in both eyes (yellow doted arc), a few flame-shaped haemorrhages in the right eye along the inferotemporal vessels (white arrow) and a few soft exudates along the superonasal vessel in the right eye (orange asterisk). (B) Humphrey visual fields in the left eye show central scotoma extending nasally (black circle). Formal perimetry was not possible in the right eye (marked black).

Given rapid presentation with marked decrease in vision in the RE and subnormal visual fields in the LE, we considered a primary differential diagnosis of papillitis versus rapidly worsening papilloedema in BE. She was advised to undergo MRI of the brain and orbits with contrast and MR venography (MRV) of the brain, if indicated.

The patient returned to clinic with reports 3 days later when she reported worsening of vision in her LE as well. Her examination showed BCVA of no light perception in the RE and 20/600 in the LE. Anterior segment examination was stable; however, there was no RAPD at this visit, with pupillary reactions being sluggish in BE. Fundus examination revealed worsening of disc oedema in BE (figure 2B). Optical coherence tomography (OCT) performed using the peripapillary RNFL showed diffuse RNFL thickening with an average thickness of 209 and 113 µm in the RE and LE, respectively. Macular ganglion cell–inner plexiform layer (MGC-IPL) analysis showed an average thickness of 79 µm in BE at presentation.

Figure 2

(A–C) Composite fundus photographs of the patient at presentation, 3 days and 7 days later showing rapid worsening of the disc oedema in both eyes.Note the obscuaration of the peripapillary RNFL (yellow arc), obscruation of the blood vessles at disc margin (orange arrow-heads), and tiny splinter hemorrhage in right eye (white arrow)

Differential diagnosis

Given her acute vision loss and rapid deterioration of vision, we initially considered a differential diagnosis of bilateral optic neuritis (papillitis), malignant hypertension, nonarteritic anterior ischaemic optic neuropathy (NAAION) and papilloedema with rapidly progressive vision loss due to space-occupying lesion, cerebral sinus venous thrombosis (CSVT), or fulminant IIH.

Given her gender, age (20–50 years), and rapid decline in BCVA involving BE, we considered bilateral optic neuritis. However, a diagnosis of typical optic neuritis could not be made because there was bilateral disc swelling and bilateral vision loss, and an absence of pain. In a young woman with progressive vision loss over a few days, inflammation could not be ruled out.

Although papilloedema usually presents with an insidious vision loss, patients with posterior fossa tumours, hydrocephalus, pituitary apoplexy and fulminant IIH may present with a rapid decline in BCVA; therefore, immediate imaging was warranted to exclude a life-threatening cause such as apoplexy or malignancy.7

Bilateral NAAION, though uncommon, is also possible. 8,9 However, it was unlikely given her young age, associated headache and the absence of vasculopathic risk factors.

Another differential diagnosis was malignant hypertension but was quickly ruled out (normal blood pressure recording and no prior history of hypertension).

Investigations

MRI of the brain with contrast revealed scleral flattening and increased perioptic spaces in BE. MRV of the brain showed only bilateral transverse sinus stenosis consistent with elevated ICP but no thrombosis (figure 3A–C), ruling out CSVT (figure 3C). Unlike long-standing cases of IIH, empty sella sign was not observed (figure 3B). Furthermore, CSF opening pressure and analysis was advised. The CSF opening pressure was 42 cm H₂O while the rest of the CSF analysis was normal.

Figure 3

(A–C) Contrast-enhanced MRI of the brain with MR venography (MRV) of the brain of the patient showing flattening of the posterior sclera (white arrow) and increased perioptic nerve sheath (yellow asterisk, A) and bilateral transverse sinus stenosis (yellow arrows, C) but no thrombosis. Note the absence of empty sella, suggesting possible lack of chronicity (B, yellow arrowhead).

A normal MRI and raised CSF pressure with normal CSF is characteristic of pseudotumour cerebri. This can be caused by medications and endocrine disorders, but without a history of these and in the presence of obesity, a narrower diagnosis of IIH was made. In her case, it was fulminant IIH as the vision loss was rapid and severe.

As optic neuritis was thought to be less likely after the lumbar puncture, further investigations for causes of optic neuritis such as myelin oligodendrocyte glycoprotein (MOG) antibody–associated optic neuritis or neuromyelitis optica (NMO) were not pursued.

Treatment

The patient was advised to undergo urgent CSF diversion procedure (thecoperiteoneal shunt (TP shunt)). However, she had difficulty arranging finances for urgent surgery, and while awaiting surgery, she was put on maximal medical therapy. She was started on increasing doses of acetazolamide at 250 mg six times per day and increasing up to 3 g/day and administered intravenous injection of methylprednisolone 1 g/day for 3 days while awaiting surgery. Of note, while awaiting surgery, her papilloedema worsened further in BE (figure 2C).

Outcomes and follow-up

The patient was kept in close follow-up, and following TP shunt she reported improvement in her vision and disc oedema. Following TP shunt, she also had relief in her headache and gradually her BCVA improved. At 12 weeks of follow-up, her examination revealed a BCVA of 20/30 in BE, normal colour vision (17/17 correct Ishihara plates), no RAPD and full ocular motility. Fundus examination revealed complete resolution of disc oedema with mild temporal pallor in BE (figure 4A). Automated perimetry showed interval improvement. While at presentation perimetry was not even possible in the RE and showed central scotoma extending nasally in the LE, at 12 weeks of follow-up she had small central scotomas in BE (black arrows) and slight enlargement of blind spot in the LE appreciated on grey scale (dotted circle). At 3 months follow-up, OCT showed RNFL thinning in BE with an average thickness of 65 µm in the RE and 69 µm in the LE. Similarly, MGC-IPL analysis showed diffuse thinning with an average thickness of 50 µm in BE.

Figure 4

(A) Fundus photographs of both eyes show resolution of disc oedema in both eyes with temporal pallor (white arrows). (B) Humphrey visual fields in both eyes show central scotoma in both eyes (black arrows) and slight enlargement of blind spot in the left eye appreciated on grey scale (dotted circle).