Saturday, March 13, 2021

Herpes Zoster Case File

Posted By: Medical Group - 3/13/2021 Post Author : Medical Group Post Date : Saturday, March 13, 2021 Post Time : 3/13/2021
Herpes Zoster Case File
Eugene C. Toy, MD, Lawrence M. Ross, MD, PhD, Han Zhang, MD, Cristo Papasakelariou, MD, FACOG

CASE 34
A 68-year-old man complains of severe burning and stinging pain across the right side of his waist over a period of 2 days. Today, he notes a rash breaking out in the same area. On examination, there is a red rash with blisters starting on his back and curving down and across his right waist region.

 What is the most likely diagnosis?
 What is the anatomical explanation for this condition?


ANSWER TO CASE 34:

Herpes Zoster
Summary: A 68-year-old man has had severe dysesthesia on his right waist for 2 days and, more recently, an erythematous vesicular (blisterlike) rash.
• Most likely diagnosis: Herpes zoster

• Anatomical explanation for this condition: Reactivation of the varicella virus and infection of the skin following the dermatomal distribution, which is in this case likely T11 or T12


CLINICAL CORRELATION
This 68-year-old man has clinical symptoms consistent with herpes zoster, also known as “shingles.” The chicken pox virus remains latent and may become reactivated years later as a result of illness, stress, or age. The varicella virus is reactivated from the dorsal root ganglia and initially causes a burning pain that follows the distribution of a dermatome, most commonly T3 through L3. Usually 2 to 3 days after the pain, a rash erupts that is erythematous and vesicular, and has a reddish blisterlike appearance. Treatment of this condition may include corticosteroid therapy, which can help to decrease the inflammation and pain. Even after the skin lesions have healed, the patient can have significant pain, called postherpetic neuralgia. The pain can persist for months or even years. Treatment of postherpetic neuralgia is difficult, and therapies include topical lidocaine gel, capsaicin cream, anticonvulsant agents, or even nerve blocks.


APPROACH TO:
The Spinal Nerves

OBJECTIVES
1. Be able to draw the components of a spinal nerve
2. Be able to draw the dermatomes of the thorax and abdomen
Definitions
DYSESTHESIA: An abnormality of somatic sensation; for example, diminished sensation approaching numbness, an uncomfortable or painful response to a normal stimulus (as in this case) or a perceived sensation in the absence of stimulation

ERYTHEMATOUS VESICULAR RASH: Skin disorder characterized by redness and pustules


DISCUSSION
Peripheral nerve fibers arise from the spinal cord as anterior (ventral) roots, which are primarily motor, and posterior (dorsal) roots, which are primarily sensory. These roots join to form the spinal nerve. The spinal nerve splits to form two mixed function branches, a small posterior primary ramus and a larger anterior primary ramus. In the abdomen, the posterior primary ramus innervates the intrinsic muscles of the back and the overlying skin. The anterior primary ramus projects anteriorly and inferiorly to innervate the muscles of the abdominal wall and the overlying skin (Figure 34-1). For a description of the peripheral distribution of spinal nerves, see Case 33.

After infecting the skin, the varicella virus is transported within the axons of sensory neurons back to the cell bodies, which are located in the posterior root ganglia. The virus periodically reactivates and is transported back out along the distribution of the spinal nerve that is carrying the sensory axons. Thus skin eruptions occur along the dermatomal distribution of the spinal nerve. In the thorax, the main dermatomal landmarks are the clavicle (L5) and nipple (T4). In the abdomen, the major dermatomal landmarks are the xiphoid process of the sternum (T7), umbilicus (T10), and inguinal/suprapubic region (L1) (Figure 34-2).

Herpes Zoster anatomy

Figure 34-1. Components of a typical spinal nerve.

cutaneous nerves over the abdomen

Figure 34-2. Distribution of cutaneous nerves over the abdomen. (Reproduced, with permission, from Lindner HH. Clinical Anatomy. East Norwalk, CT: Appleton & Lange, 1989:302.)


COMPREHENSION QUESTIONS

34.1–34.4 Match the following nerve roots (A–F) to their locations on the body.
    A. C5
    B. C7
    C. T1
    D. T4
    E. T7
    F. T10

34.1 Umbilicus
34.2 Nipple
34.3 Xiphoid process
34.4 Clavicle


ANSWERS
34.1 F. T10 innervates the skin around the umbilicus.
34.2 D. T4 innervates the nipple area.
34.3 E. T7 innervates the xiphoid process of the sternum.
34.4 A. C5 innervates the skin over the clavicle.


ANATOMY PEARL
 Peripheral nerve fibers arise from the spinal cord. Anterior (ventral) roots are primarily motor, whereas posterior (dorsal) roots are primarily sensory.
 In the abdomen, the major dermatomal landmarks are the xiphoid process of the sternum (T7), umbilicus (T10), and inguinal and suprapubic regions (L1).
 In the thorax, the major dermatome landmarks are the clavicle (C5) and the nipple (T4).

References

Gilroy AM, MacPherson BR, Ross LM. Atlas of Anatomy, 2nd ed. New York, NY: Thieme Medical Publishers; 2012:42−43, 66−68. 

Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy, 7th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014:193−195, 496−498. 

Netter FH. Atlas of Human Anatomy, 6th ed. Philadelphia, PA: Saunders; 2014: plates 162, 174, 253−254.

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