Brian Kohen, MD; Meghan Kelly Herbst, MD, FACEP
A 27-year-old female with a history of morbid obesity, migraines, anxiety, and depression presented with five days of severe generalized headache associated with nausea, vomiting, photophobia, and phonophobia. She stated that her headache was similar to previous headaches but had been unresponsive to her prescribed sumatriptan. She denied fevers, chills, neck stiffness, or vision changes. She denied taking oral contraceptive pills. This was her sixth visit to an emergency department (ED) or urgent care for similar symptoms over the past 5 days. During those visits she received different medications including dexamethasone, prochlorperazine, hydromorphone, and haloperidol, noting that the only medications that provided some relief were hydromorphone and haloperidol. On her visit the day prior, she received intravenous fluids, promethazine, fentanyl, magnesium sulfate, and ketorolac after which the ED provider documented improvement in her symptoms and discharged her home.
On the current visit, she was afebrile and hemodynamically stable with a blood pressure of 152/94 mmHg. Her body mass index was 41.5 kg/m2. Her physical examination was unremarkable without focal neurological deficits. A complete blood count and basic metabolic panel were unremarkable. She received one liter of normal saline, dexamethasone, ketorolac, magnesium sulfate, and promethazine with minimal improvement in her symptoms. Intravenous tylenol and haloperidol were added and the patient became somnolent but still complained of severe headache. The patient was seen by neurology in the emergency department, who did not appreciate any papilledema on her fundoscopic exam and requested an MRI head, MRV with contrast, and admission for observation.
Subsequently, an ocular point-of-care ultrasound (POCUS) was performed by the emergency physician. The high-frequency linear transducer was oriented transversely on each eye, and the patient was found to have optic nerve sheath diameter (ONSD) > 5mm bilaterally (OS 5.9mm, OD 5.8mm) as well as protrusion of the optic nerve papilla into the globe bilaterally (Video). In the clinical setting of an obese young female with intractable headaches, nausea, vomiting and POCUS suggestive of papilledema, idiopathic intracranial hypertension (IIH) was suspected. A lumbar puncture was performed and revealed an opening pressure of > 60cm H2O, diagnostic for IIH. Closing pressure, after collection of cerebrospinal fluid (CSF) in four tubes and draining several milliliters per IIH treatment recommendations was 26 cm H2O. CSF analysis revealed a glucose of 75 mg/dL and protein of 14 mg/dL.
POCUS of the eye, with its sonographically-friendly vitreous humor, allows non-invasive visualization of the anterior chamber, posterior chamber, and optic nerve. This application can be used to rapidly evaluate for ocular pathologies such as retinal detachment, vitreous detachment, vitreous hemorrhage, retrobulbar hematoma, globe rupture, pupillary function, and optic neuritis.
In the setting of headache, POCUS can provide information on the presence of papilledema and elevated intracranial pressure (ICP) with greater ease and fewer limitations than fundoscopy.
Several studies have looked at measuring the diameter of the optic nerve 3 mm posterior to the retina, where a value 5 mm or larger is concerning for elevated intracranial pressure.1-7 Blaivas et al. was one of the first emergency physicians to compare ONSD using POCUS to computed tomography (CT) scan findings. Fourteen of the 35 patients enrolled in the study were found to have increased ICP on CT scan, and all cases were correctly identified on POCUS. The study found that the sensitivity and specificity for POCUS ONSD when compared to CT scan results were 100% and 95%, respectively.8 A meta-analysis performed in 2015 evaluated 12 studies with a total of 478 participants and found a sensitivity of 95.6% and specificity of 92.3%, providing further evidence that ocular US is an accurate diagnostic test for assessing increased ICP.9
More recently, attention has shifted to the specific finding of a bulging papilla into the globe, which may be easier to detect in B-mode scanning with higher inter-rater reliability. Dr. Stone commented on this in Figure 1 of his pseudotumor cerebri case report in 2009.10 A study performed in 2013 revealed that a disc height > 0.6mm measured on POCUS predicted papilledema as seen on fundoscopic exam with 82% sensitivity and 76% specificity. When increasing the disc height to 1.0 mm, sensitivity decreased to 73%, however specificity increased to 100%. These measurements were compared to optical coherence tomography (OCT) measurements of optic disc height and showed statistically significant correlation (r = 0.836) in measurements.11
In this case, the patient reported symptoms similar to previous headaches, had been seeing a neurologist, and carried a diagnosis of migraine. A limited fundoscopic exam did not demonstrate papilledema, but this exam can be difficult in a nondilated pupil.11 By incorporating POCUS, a more accurate diagnosis of IIH was established in the emergency department and allowed for improved management of her symptoms.
1. What are the findings of this point-of-care ultrasound (POCUS) exam?
The video demonstrates both dilation of the ONSD > 5mm, as well as protrusion of the optic nerve papillae into the globe.
2. What is the differential diagnosis for these findings?
These findings are consistent with papilledema and elevated intracranial pressure. A differential for these findings includes idiopathic intracranial hypertension (formerly “pseudotumor cerebri”), as well as meningitis and mass-occupying intracranial lesions such as tumors and bleeding.
3. What additional testing would help confirm the etiology for these findings?
Depending on the context of the patient presentation, diagnostic testing may include lumbar puncture with opening pressure and/or CSF cell count, glucose, and protein to assess for idiopathic intracranial hypertension and intracranial infection. Alternatively, if trauma or history suggests mass-occupying lesions, radiographic imaging including head CT and/or MRI would be appropriate.