Patient with headache and diplopia.

PATIENT PRESENTATION

A 46‐year‐old female with a past medical history of obesity and uterine fibroids presented to the emergency department (ED) with a 4‐day history of worsening left sided headache and inability to abduct her left eye past midline. The onset of the headache was spontaneous and described as a pressure that worsened with eye movement. She also experienced nausea, diplopia, photophobia, blurry vision, and phonophobia. On examination, she was unable to abduct her left eye past the midline, suggesting a cranial VI nerve palsy of the left eye (Figure 1). She otherwise had an intact neurologic examination. Bedside ultrasound was obtained that showed bilateral dilation of the optic nerve sheath to 6.8 mm—normal is <5 mm (Figure 2). Ophthalmology evaluated and confirmed papilledema on exam. The patient subsequently received computed tomography angiogram and magnetic resonance imaging (MRI) of the head. The patient gave written consent for the use of these images.

FIGURE 1

Lack of abduction of the left eye suggesting cranial nerve VI palsy

FIGURE 2

Ultrasound showing enlarged optic nerve sheath

DIAGNOSIS

Idiopathic intracranial hypertension

The woman experienced idiopathic intracranial hypertension (IIH) leading to headache, visual disturbances, and a cranial VI nerve palsy. This case describes a typical patient with IIH and multiple possible associated sequelae. As a female of childbearing age and obesity, she was part of the population most at risk for IIH. Her MRI of the head showed prominence of the bilateral optic nerve sheaths with vertical tortuosity as well as prominence of the bilateral Meckel's cave suggestive of idiopathic intracranial hypertension. Neurology and ophthalmology evaluated the patient in the ED. She had improvement in her headache with Benadryl and Compazine. Ultimately, she was discharged with a Diamox prescription and outpatient neurology follow‐up.

IIH is defined as elevated intracranial pressure (ICP) in a patient with normal cerebral spinal fluid composition and no intracranial pathology. Symptoms associated with IIH include nausea, diplopia, headaches, tinnitus, and vision loss. It is thought that increased ICP from IIH leads to many of the symptoms and can increase pressure on the optic nerve sheath leading to visual deficits. Radiographic findings of optic nerve sheath enlargement on ultrasound or MRI are suggestive of IIH. Cranial nerve VI (abducens) palsy is also an associated sign and can be seen with IIH. The sixth cranial nerve can be compressed by the increase in ICP, leading to dysfunction of the lateral rectus muscle, which receives innervation from cranial nerve VI, leading to a lack of abduction in the affected eye.