Herpes zoster infection (shingles): Clinical sciences

Herpes Zoster infection, also known as shingles, occurs in individuals who have had a primary infection called varicella, or chickenpox, which is caused by the Varicella Zoster Virus. Following the primary infection, the virus remains dormant in the dorsal root ganglia of spinal nerves or the trigeminal ganglion. In times of stress or immunosuppression, the virus can reactivate and travel down the sensory neurons, causing herpes zoster.

Now, if your patient presents with a chief concern suggesting herpes zoster infection, first you should perform an ABCDE assessment to determine if your patient is unstable or stable. If the patient is unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access and put your patient on continuous vital sign monitoring including heart rate, blood pressure, and pulse oximetry. Finally, If needed, provide supplemental oxygen.

Now, here’s a high-yield fact to keep in mind! If your patient is unstable, they may have disseminated herpes zoster, which can present with associated hepatitis, encephalitis, or meningitis. This can happen because of compromised cell-mediated immunity, or following hematopoietic stem cell transplant, in which case high viremia causes an atypical presentation. These patients can also be unstable on presentation because of the high viral load.

Okay, now let’s go back to the ABCDE assessment and take a look at stable patients. If your patient is stable, obtain a focused history and physical exam. History typically reveals a prior history of varicella infection, as well as a painful, itchy, or tingly rash that may have been preceded by a prodromal illness of malaise, headache, fatigue, and a low-grade fever.

Physical exam typically reveals a maculopapular or vesicular rash in the distribution of 1 to 2 adjacent dermatomes, which are areas of skin innervated by a single nerve. Typically, the rash appears on the trunk or the face, and it doesn’t cross the midline! At this point, you can clinically diagnose Herpes Zoster infection!

Now, keep in mind that the diagnosis of zoster infection is typically made clinically. However, in those cases where clinical findings aren’t enough to make the diagnosis, you can unroof a vesicle and use a PCR swab to detect the viral DNA and confirm the diagnosis! Other diagnostic methods include the Tzanck test or smear, which detects multinucleated giant cells in the vesicle fluid; and the detection of serum IgM antibodies against the varicella-zoster virus.

Now, here’s a high-yield fact! Some patients can present with herpes zoster ophthalmicus, which occurs when the virus reactivates in the trigeminal ganglion and travels down the ophthalmic nerve. This can affect all parts of the eye, including the retina, and eventually cause retinal detachment and necrosis, which can compromise longstanding vision.