Medical Student Corner
Headache

A 40 year old white male is seen in the Emergency Room for the chief complaint of a headaches, which began abruptly three days ago, and has progressively worsened since then.

Prior to the onset of his headaches, he noted several days of intermittent fevers, fatigue, chills, sweats, and "confusion."

The headaches are described as diffuse, very severe, and sharp, and worsen when he "looks at light."

The patient denies hearing loss, visual changes, tinnitus, or motor or sensory defects.

Of note, he states that he may have been bitten by an insect, "possibly a mosquito," on his right forearm several days prior to onset of headaches.

No previous episodes are reported.

He now presents for further evaluation and management.

On exam, he appears fatigued and somewhat disoriented.

Temperature is 101.1F, pulse is 95, blood pressure is 110/70 and respirations are 16.

Aside from moderate neck stiffness, the remainder of the patient's examination, including throat, chest, heart, abdomen, and extremity exam are within normal limits.

Laboratory studies, including urinalysis, are normal.

The results of a lumbar puncture are pending.

Upon closer examination, you note the presence of a subtle physical finding that you and the team had previously overlooked:

Further evaluation with a magnifying glass reveals the following lesion on the patient's forehead:

What's going on?

Answer: St. Louis Encephalitis

This man most likely has St. Louis Encephalitis, an arthopod-borne illness whose vector is the Culex mosquito, prevalent in the Western and Central U.S. during the months of June through October.

The presence of the Gateway Arch, a national landmark located in St. Louis, MO, on the forehead of a patient with headache, fever, and confusion is pathognomonic for St. Louis Encephalitis.

It is often difficult to detect the presence of the Gateway Arch on a patient's forehead without the use of special diagnostic equipment; therefore, a strong clinical suspiscion is invaluable in making the diagnosis.

St. Louis Encephalitis differs from other conditions in which an arch appears on a patient's forehead by the presence of a large riverboat near the arch, as seen in the close-up above.

Treatment involves supportive care, and frequent wiping of the forehead with hydrogen peroxide.