Atypical Presentation of Idiopathic Intracranial Hypertension

Author:
Brittany Gallaher, DO
Family Medicine Resident PGY-3, Kaiser Permanente
 

Citation:
Gallaher B. Atypical presentation of idiopathic intracranial hypertension. Consultant. 2015;55(1).

A 26-year-old female presented with a complaint of intermittent vision changes in her left eye of a 5-month duration. Episodes that lasted 1 to 8 seconds were described as darkening of vision in her left eye, which was worse medially and accompanied by a sensation of tunnel vision in the left eye when standing after waking in the morning. The patient denied blurry vision, double vision, bright flashes of light, or eye pain. She also denied headaches, neurological deficits, or hearing changes. 

Physical examination. The patient had normal vital signs but was noted as obese with a body mass index of 33.5. Vision was 20/20 bilaterally with corrective lenses; extraocular muscles were intact. On ophthalmologic slit lamp exam, she was found to have moderate-to-severe papilledema bilaterally, worse in left eye. CT of brain and orbits was negative for mass or space occupying lesions. Formal visual field testing (perimetry) revealed a defect in the left eye (Figure). The patient was then evaluated by neurology and had lumbar puncture done. Cerebrospinal fluid analysis (CSF) studies were within normal limits. Opening pressure was 42 mm Hg (normal: ≤20 mm Hg).

Figure. Initial perimetry results showing visual field defect in the left eye.

Discussion. The patient was diagnosed with idiopathic intracranial hypertension (IIH). The patient lacked the usual presenting symptom of headache, but still met the modified Dandy criteria for diagnosis of IIH. The criteria includes that patients show signs and symptoms of generalized intracranial hypertension, have a documented elevated CSF pressure while done in the lateral decubitus position, a normal CSF composition, no evidence of hydrocephalus or space-occupying lesion on neuroimaging, and no other cause of intracranial hypertension identified.^1-3 

Symptoms. Headaches are present in as many a 68% to 98% of cases of IIH.² Visual symptoms are the second most common symptom—usually described as blurry or double vision, as well as transient visual obscurations in which the patient experiences brief episodes of vision loss with a rapid return to normal. Other symptoms of IIH include pulsatile tinnitus and rarely neck and shoulder pain, nausea and vomiting, and photophobia. 

IIH more commonly affects obese women. The incidence of IIH in obese women of child bearing age is reported to be 15 to 19 per 100,000.² Often, weight gain in the year preceding symptom onset is noted to be increased. This patient experienced only vision loss symptoms, which some studies have shown is only present in approximately 20% of cases,⁴ but it is less common to only have vision changes unilaterally and without blurred or double vision. 

Often, patients that present without headache have a more severe vision loss at the time of diagnosis.⁵ Factors found to be related to degree of vision loss are recent weight gain, high grade papilledema, significant visual field loss at presentation, and hypertension.⁶ The degree of headache, duration of symptoms, transient visual obscurations, and opening pressure during lumbar puncture were not predictive of vision loss. 

Treatment. The goals of treatment of IIH are to reduce permanent vision loss and to control symptoms, such as headaches. The mainstay of treatment is weight reduction, although it is unknown how weight relates to the disease process. Many studies have shown that weight loss of 5% to 10% of body weight reduces signs and symptoms.⁶ When weight loss alone is not adequate for symptom management, other treatment options include medication (eg, acetazolamide). In severe cases, surgery can be considered. 

A ventriculoperitoneal shunt can be placed for drainage of CSF. To prevent further vision loss, optic nerve sheath fenestration can be performed. In patients without headache, careful monitoring and surveillance with serial eye exams and visual field testing is needed to monitor response to treatment, stability of disease, and recurrence. 

Outcome of the case. The patient had 40 cm³ of CSF removed on initial lumbar puncture. She developed severe headache worsened by an upright position and was treated with a blood patch for postlumbar puncture spinal leak. 

She was started on acetazolamide 250 mg twice daily and encouraged to lose weight; she lost approximately 12% of her body weight through low calorie diet and exercise. Acetazolamide was tapered and discontinued after 6 months of therapy. Repeat visual field testing revealed resolution of visual defect in left eye and resolution of papilledema on slit lamp exam.

The patient became pregnant 4 months later and experienced mild exacerbation in symptoms, but was controlled with minimal weight gain. Symptoms resolved after delivery.

References:

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