Case of the month- courtesy of Dr. Beck-Esmay

A 35yo female presented to the ED with headache for 2 weeks.  She had associated nausea, neck stiffness/soreness and mild dizziness.  Her past medical history was significant for gestational diabetes and a lower extremity DVT during pregnancy.  In the ED, she had a noncontrast head CT, which demonstrated a right posterior fossa hypodensity consistent with an arachnoid cyst or epidermoid.  Bedside ultrasound was performed and demonstrated the following:

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Bedside ocular ultrasound demonstrates dilation of the optic nerve sheath, as well as some flattening of the posterior globe and a bulging of the optic disc consistent with elevated intracranial pressure.  The patient was admitted to neurology, underwent MRI/MRV and a lumbar puncture, which revealed an opening pressure > 46cmHg.  Her headache resolved after drainage of spinal fluid.   The findings were consistent with pseudotumor cerebri. The patient was discharged home with markedly improved symptoms on acetazolamide and counseling on weight reduction.

Bedside ocular ultrasound is a rapid, non-invasive method that can provide high-yield information.  It is often challenging in the Emergency Department to perform a comprehensive fundoscopic exam (pupillary dilatation/direct ophthalmoscopy).  The relationship between optic nerve sheath diameter (ONSD) and intracranial pressure has been established- as an ONSD measuring > 5mm (taken 3mm behind the globe) correlates with an elevated intracranial pressure.