Benign intracranial hypertension associated with inhaled corticosteroids in a child with asthma

Background

Benign intracranial hypertension (BIH), also known as idiopathic intracranial hypertension and pseudotumor cerebri syndrome, is a rare neurological condition characterised by raised intracranial pressure and papilloedema. Neuroimaging and cerebrospinal fluid (CSF) analysis are normal. It is most commonly associated with obesity and occurs more often in women than men. The typical presenting features are headache and visual disturbance. There may be associated cranial nerve palsies. Although described as a benign condition, there can be severe and permanent visual impairment if left untreated. While BIH is often idiopathic, it can be associated with medications such as retinoids, tertacyclines and corticosteroids. Corticosteroids can cause BIH when used for prolonged periods of time. Withdrawal of corticosteroids leading to adrenal insufficiency can also lead to the development of BIH.

This case involves a teenager with asthma who developed BIH associated with moderate-dose inhaled corticosteroids without evidence of adrenal insufficiency.

Case presentation

A 13-year-old boy with a history of asthma, eczema and allergic rhinitis was seen in the general paediatric clinic with papilloedema. He had presented to his optician with blurred vision who was concerned about the development of papilloedema that had not been present previously. There were no associated headaches, tinnitus, transient visual obscurations, behavioural changes or vomiting.

His asthma was well controlled since an admission 18 months previously on fluticasone propionate 125 µg two puffs twice a day (total dose 500 µg daily) and montelukast 5 mg at night. His mother reported excellent compliance with his medication and he rarely missed a dose. He remained asymptomatic with no exertional or nocturnal symptoms, nor required any oral steroids for over a year. Apart from his inhaled fluticasone, he was not taking any other forms of corticosteroids.

On examination, he had a normal neurological and respiratory examination. He was growing along the 90th centile for weight and between 75th and 90th centile for height with a normal BMI of 21 kg/m². He was reviewed by a consultant ophthalmologist who confirmed bilateral papilloedema on funduscopy and orbital ultrasound scan (see figures 1 and 2). The history and examination findings were compatible with raised intracranial pressure and he was referred for a lumbar puncture to assess CSF opening pressure.

Figure 1

Left eye funduscopic appearance demonstrating papilloedema.

Figure 2

Right eye funduscopic appearance demonstrating papilloedema.

Investigations

An MRI brain scan was performed which demonstrated an incidental finding of an arachnoid cyst in the middle cranial fossa on the left side. There was no mass effect or oedema and no significant abnormality of the orbits. Lumbar puncture was performed which demonstrated an elevated opening pressure of 30 cm of H₂O. CSF microscopy and biochemical analysis was normal. Investigations for potential causes of raised intracranial pressure including vitamins A and D, autoimmune disease, anti-MOG antibodies and thyroid function tests were all normal or negative. In addition, a cortisol level checked at 9:00 was 546 nmol/L making adrenal suppression very unlikely.

Differential diagnosis

A diagnosis of raised intracranial pressure was made based on the high CSF opening pressure. A diagnosis of BIH was made based on the American Academy of Neurology diagnostic criteria.1

BIH is most often seen in patients with obesity or significant recent weight gain, and it is also more common in females. While this patient had gained 15 kg in the preceding year, his weight remained in proportion to his height with a normal BMI.

Vascular causes of BIH were excluded based on normal MRI. Hypervitaminosis A can also cause BIH, but the level was normal in this case. Adrenal suppression secondary to medications or autoimmune disease has been associated with BIH, but this was excluded based on a normal early morning cortisol level. High-dose corticosteroids have been associated with the development of BIH. This is most often seen in patients on long-term oral corticosteroids or due to adrenal insufficiency following withdrawal of treatment.

In this case, a diagnosis of BIH associated with inhaled corticosteroids was made based on the aforementione findings.

Treatment

The patient was referred to a paediatric respiratory consultant for ongoing care of his asthma. The dose of inhaled corticosteroid was slowly weaned over the following 3 months. His asthma is currently well controlled on Seretide (fluticasone propionate 50 µg and salmeterol 25 µg) one puff twice a day (total dose 100 µg daily). He was commenced on oral acetazolamide and this has been weaned with an aim to discontinue in the coming months.

Outcome and follow-up

The patient’s papilloedema improved following reduction in the dose of corticosteroids. At no point did he develop a headache or vomiting.

Follow-up ophthalmology assessment demonstrated improvement in the appearance of the papilloedema and is now fully resolved 3 months after presentation with retinal nerve fibre layer thickness within normal limits. Visual field examination was normal and visual acuity was at his pre-morbid baseline 6 months following initial presentation.