History and Physical
A 17-year-old female patient comes to the emergency room with a headache of 5 weeks’ evolution. She describes the headache as pulsatile with a severity of 6-7/10, bilateral frontal in location, with retroorbital pressure and photophobia but no phonophobia, nausea, or vomiting. She also reports blurred and tunnel vision, mainly when bending over to tie her shoes, and intermittent pulsatile tinnitus. She has no history of medications, contraceptives, or vitamins and unremarkable personal and family history. Physical examination, including vital signs, is normal. Body mass index is above the 95th percentile. Neurological examination is significant for 3+ papilledema showing significant optic disc protrusion. Vision acuity is 20/20 in both eyes, but campimetry demonstrated an enlarged blind spot.
Diagnostic Workup
MRI shows partially empty sella with a concave superior margin of the pituitary gland ( Fig. 2.1 ), as well as dilated optic nerve sheaths with inversion of the optic discs compatible with papilledema and increased intracranial pressure ( Fig. 2.2 ). There is no evidence for dural sinus thrombosis or meningitis.
Partially empty sella. Brain MRI, sagittal T1 with gadolinium, demonstrates a concave superior surface of the pituitary gland ( arrow ).
Optic nerve sheath dilation. Brain MRI, coronal T2, shows engorged optic nerve sheaths (green) measured 3 mm posterior to the globe.
In the emergency room, a lumbar puncture (LP) shows an opening pressure of 29 cm H 2 O and a closing pressure of 18 cm H 2 O. CSF is negative for cytology and cultures.
Clinical Differential Diagnosis
Primary headaches: Tension headache and migraine have characteristic clinical features and normal CSF pressures.
Drug overuse headache: Patients on chronic analgesics.
Idiopathic intracranial hypertension (IIH): Obesity, cranial nerve (CN) palsies as “false localizing signs,” and papilledema.
Secondary intracranial hypertension: various etiologies including cerebral edema, venous thrombosis, hydrocephalus, infection, and tumor. Neuroimaging is valuable to distinguish from IIH.
Imaging Differential Diagnosis
Dural sinus thrombosis presents with filling defects in the venous sinuses, and parenchymal venous infarcts if advanced.
Empty sella can be an incidental imaging finding in patients with normal CSF pressure and incompetence of the diaphragma sellae.
Final Diagnosis
Idiopathic intracranial hypertension.
Discussion
IIH or pseudotumor cerebri describes the condition of increased intracranial pressure in the absence of a mass or other primary etiology. The incidence is higher in obese females, but prepubertally affects males and females in equal numbers. The most frequent symptom is a high-pressure headache, which can worsen with Valsalva maneuvers and lying down. Other possible symptoms and signs include diplopia, pulsatile tinnitus, visual dimness, nausea, vomiting, CN signs (often VI), and papilledema.
Diagnostic criteria for IIH:
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A.
Papilledema.
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B.
Normal neuroimaging using MRI with and without gadolinium, or CT with contrast if MRI is not available. Signs of increased intracranial pressure may be present but without an underlying mass.
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C.
Normal neurological examination, except for CN signs.
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D.
CSF testing normal.
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E.
Elevated CSF opening pressure (>25 cm H 2 O in adults and >28 cm H 2 O in children, or 25 cm H 2 O if nonsedated and not obese) with appropriate pressure collection.
Diagnosis is definite if criteria A to E are fulfilled. Diagnosis is considered probable if criteria A to D are fulfilled, but CSF pressure is lower than the threshold for definitive diagnosis.
In absence of papilledema, criteria B to E must be present, and in addition, patient must have CN VI palsy (uni- or bilateral).
In absence of papilledema and CN VI deficits, diagnosis can be suspected but not confirmed, and neuroimaging must show signs of elevated intracranial pressure.
Clinical Red Flags
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Progressive headache, aggravated by Valsalva maneuver or lying down.
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Headaches awakening from sleep, with or without vomiting.
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Headache with visual obscurations, diplopia, papilledema.
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Headache with focal neurological signs, especially CN VI palsy.
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