Idiopathic Intracranial Hypertension: A True Diagnosis of Exclusion

By:

Rodney Jacob Gunn, OD [email protected] (714) 553-5449 Group Health Cooperative Optometry Resident Tacoma, WA

Abstract (35 words): Idiopathic intracranial hypertension is a disorder of increased CSF pressure of unknown cause. This case demonstrates a 46-year-old obese female with papilledema, normal imaging studies and lumbar puncture whose symptoms improved with acetazolamide.

Outline: I. Case History:

- Patient Demographics / Chief complaint: 46-year-old white female was referred to the eye clinic for confirmation of Papilledema. She presented earlier that day to urgent care complaining of a pulsatile headache and nausea for the past 3-4 weeks. She also reported vertigo that’s occurred on and off for the past year. She denied symptoms of tinnitus, photophobia, and double vision. - Ocular History: Compound myopic astigmatism corrected with soft toric contact lenses Early Presbyopia corrected with +1.50 over the counter readers. - Medical history: Hypertension Fibromyalgia Anxiety Benign neoplasm of colon - Medications: Triamterene-Hydrochlorothiazide 75/50mg Duloxetine 60mg Amitriptyline 100mg at bedtime Calcium Carbinate 500mg Cetirizine as needed

II. Pertinent Findings

- Clinical Height: 5’5 Weight: 270 lb. Body Mass Index: 45.02 Blood Pressure: 132/80 Visual Acuity Corrected with Contact Lenses: OD: 20/20 OS: 20/20 Color Vision Normal by Pseudoisochromatic Plates OD and OS Pupils equal round responsive to light with no afferent pupillary defect

- Physical Anterior segment health unremarkable Dilated fundus exam remarkable for bilateral nasal disc edema OS > OD (As shown below)

Figure 1: Stereo photographs of the right optic nerve with nasal optic nerve edema.

Figure 2: Stereo photographs of the left optic nerve nasal optic nerve edema.

- Laboratory Studies Complete Blood Count with Differential showed slightly elevated white blood cells, neutrophils, and monocytes deemed to be acceptable by her primary care doctor.

- Radiology Studies Cat Scan was unremarkable.

MRI/MRV: As shown below.

Figure3: Top left: Sagittal T1 image of the brain. Top Right: Magnetic resonance venogram. Bottom Left: Axial T1 illustrating the globes and optic nerve. Bottom Right: Axial T2 illustrating globes and optic nerve.

- Others Lumbar Puncture: Opening Pressure 70mm H2O Approximately 9 cc of clear CSF fluid was collected, laboratory analysis showed normal content with no cell growth on cultures. Humphrey Visual Field 30-2SS OD: generalized depression without specific pattern, MD -4.13, PSD 2.96 OS: generalized depression (more dense than OD) with a cluster of superior peripheral points. MD -5.15 / PSD 3.41 (Fields will be available to be displayed for poster)

III. Differential Diagnosis - Primary/Leading Idiopathic Intracranial Hypertension - Others Bilateral optic neuritis Papilledema from a secondary cause including hydrocephalus, venous sinus thrombosis, medications, tumor, or others…

IV. Diagnosis and discussion

After having ruled out all other causes of papilledema this patient was diagnosed with Idiopathic Intracranial hypertension (IIH). IIH previously called Pseudotumor cerebri is a diagnosis of exclusion. It’s most commonly seen in obese females of childbearing age. The signs and symptoms of IIH include symptoms of intracranial hypertension with out localizing signs, no evidence of deformity or obstruction of the ventricular system and neurodiagnostic studies are otherwise normal except for increased intracranial pressure1. This patient met all these criteria except the definition of increased intracranial pressure, defined as >200mmH2O or 250 mmH2O in obese individuals. Despite this the attending Neurologist decided to continue with the diagnosis of IIH.

V. Treatment, Management Weight loss Acetazolamide

- Treatment and response to treatment Treatment generally depends on the course of IIH which can be highly variable and is structured around relieving symptoms and preventing vision loss. The treatment is generally weight loss, high dose carbonic anhydrase inhibitors, and serial lumbar punctures. Some patients may see improvement in their symptoms after the diagnostic lumbar puncture2. Our patient reported an improvement in her symptoms after a week of acetazolamide, and is continuing to be followed for her visual field and papilledema. Acetazolamide is a common treatment for IIH although no trial data is available. Currently underway is a National Eye Institute sponsored study called the Idiopathic Intracranial Hypertension Treatment Trial (IHTT)(http://www.nordicclinicaltrials.com). The IHTT is comparing the efficacy of acetazolamide and placebo in the treatment of IIH in patients with moderate visual loss.

VI. Conclusion

The annual incidence of IIH is 3.5/100,000 in women 15 to 44 years of age and is increasing in incidence in parallel with the current epidemic of obesity3. In the presence of papilledema IIH is diagnosed by performing neurodiagnostic studies and a lumbar puncture to rule out other causes of increased intracranial pressure. The treatment typically involves serial lumbar punctures, weight loss, and high dose carbonic anyhydrase inhibitors. The last of which is being studied by the IHTT as to its efficacy in treating patients with IIH and moderate vision loss. Patients with IIH should be followed with regular automated visual fields, and dilated fundus exams to monitor both their vision loss and papilledema respectively.

References:

1. Corbet JJ, Mehta MP. Cerebrospinal fluid pressure in normal obese subjects and patients with pseudotumor cerebri. Neurology 1983;33:1386-8 2. De Simone R, Marano E, Fiorillo C, et al. Sudden re-opening of collapsed transverse sinuses and longstanding clinical remission after a single lumbar puncture in a case of idiopathic intracranial hypertension. Pathogenetic implications. Neurol Sci 2005;25(6):342-344 3. Radhakrishnan K, Ahlskog JE, Cross SA, et al. Idiopathic intracranial hypertension (pseudotumor cerebri). Descriptive epidemiology in Rochester, Minn, 1976 to 1990. Arch Neurol 1993;50:78-80.